cloud computing for smart grid applications

18
1 3 Cloud Computing for Smart Grid applications 4 5 6 Melike Yigit Q1 a,, Vehbi C. Gungor b , Selcuk Baktir a 7 a Department of Computer Engineering, Bahcesehir University, Faculty of Engineering, Ciragan Cad. Osmanpasa Mektebi Sok. No: 4-6, 34353 Besiktas, 8 Istanbul, Turkey 9 b Department of Computer Engineering, Abdullah Gul University (AGU), Faculty of Engineering, Barbaros Mahallesi, Erkilet Bulvari, Kocasinan, Kayseri, Turkey 10 12 article info 13 Article history: 14 Received 6 August 2013 15 Received in revised form 29 November 2013 16 Accepted 12 June 2014 17 Available online xxxx 18 Keywords: 19 Smart Grid 20 Cloud Computing 21 Smart Grid and Cloud Computing 22 architecture 23 Cloud Computing based Smart Grid 24 applications and projects 25 26 abstract 27 A reliable and efficient communications system is required for the robust, affordable and 28 secure supply of power through Smart Grids (SG). Computational requirements for Smart 29 Grid applications can be met by utilizing the Cloud Computing (CC) model. Flexible 30 resources and services shared in network, parallel processing and omnipresent access 31 are some features of Cloud Computing that are desirable for Smart Grid applications. Even- 32 though the Cloud Computing model is considered efficient for Smart Grids, it has some con- 33 straints such as security and reliability. In this paper, the Smart Grid architecture and its 34 applications are focused on first. The Cloud Computing architecture is explained thor- 35 oughly. Then, Cloud Computing for Smart Grid applications are also introduced in terms 36 of efficiency, security and usability. Cloud platforms’ technical and security issues are ana- 37 lyzed. Finally, cloud service based existing Smart Grid projects and open research issues are 38 presented. 39 Ó 2014 Published by Elsevier B.V. 40 41 42 43 1. Introduction 44 The Smart Grid (SG) is used by electric power utilities to 45 track and control power usage of consumers. In SGs, the 46 governance of energy usage is done in real time with the 47 ability of smart meters’ bidirectional communication [1]. 48 A more reliable and secure communication is guaranteed 49 with the SG’s distributed energy management feature 50 which is called as load balancing. Electric power utilities 51 achieve preferable operation and management of their 52 electric power systems by monitoring their energy usage. 53 When consumed energy reaches peak levels, signals are 54 sent to consumers to reduce energy consumption. In this 55 way, the SG balances its energy load [2]. Entire power 56 supply system and protection devices are monitored by 57 control centers for providing security of SG’s load balanc- 58 ing system during communication. Cloud Computing (CC) 59 is used to perform this communication process between 60 substations and power supply companies’ power plants. 61 Built-in redundancy is utilized to increase the reliability, 62 security and robustness of this communication [3]. In this 63 context, scalable platforms are needed to run many SG 64 applications when data intensity is high. Over the time of 65 the day, the resource requirement varies as the utilization 66 differentiates between day (peak operation) and night 67 (lower level operation). CC platforms can be utilized for 68 obtaining scalable, elastic, secure, robust and sharable 69 resources in order to build and operate a functional SG 70 architecture [3]. 71 Utilities and consumers take the security and privacy of 72 their data very seriously. This affects the acceptance of SGs 73 provided by cloud platforms, i.e. the privacy issues for the 74 users should be addressed by the utilities [4,5]. CC 75 platforms chosen for SG applications should realize high 76 assurance in their communication systems. There are some 77 performance issues related to the use of cloud platforms for http://dx.doi.org/10.1016/j.comnet.2014.06.007 1389-1286/Ó 2014 Published by Elsevier B.V. Corresponding Q2 author. Tel.: +90 5542403593. E-mail addresses: [email protected] (M. Yigit Q1 ), cagri. [email protected] (V.C. Gungor), [email protected] (S. Baktir). Computer Networks xxx (2014) xxx–xxx Contents lists available at ScienceDirect Computer Networks journal homepage: www.elsevier.com/locate/comnet COMPNW 5325 No. of Pages 18, Model 3G 26 June 2014 Please cite this article in press as: M. Yigit Q1 et al., Cloud Computing for Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/ 10.1016/j.comnet.2014.06.007

Upload: selcuk

Post on 26-Jan-2017

214 views

Category:

Documents


1 download

TRANSCRIPT

Page 1: Cloud Computing for Smart Grid applications

1

3

4

5

6 Q1

789

10

1 2

1314151617

1819202122232425

2 6

4243

44

45

46

47

48

49

50

51

52

53

54

55

56

Q2Q1

Computer Networks xxx (2014) xxx–xxx

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

Contents lists available at ScienceDirect

Computer Networks

journal homepage: www.elsevier .com/ locate/comnet

Cloud Computing for Smart Grid applications

http://dx.doi.org/10.1016/j.comnet.2014.06.0071389-1286/� 2014 Published by Elsevier B.V.

⇑ Corresponding author. Tel.: +90 5542403593.E-mail addresses: [email protected] (M. Yigit), cagri.

[email protected] (V.C. Gungor), [email protected](S. Baktir).

Please cite this article in press as: M. Yigit et al., Cloud Computing for Smart Grid applications, Comput. Netw. (2014), http://dx.10.1016/j.comnet.2014.06.007

Melike Yigit a,⇑, Vehbi C. Gungor b, Selcuk Baktir a

a Department of Computer Engineering, Bahcesehir University, Faculty of Engineering, Ciragan Cad. Osmanpasa Mektebi Sok. No: 4-6, 34353 Besiktas,Istanbul, Turkeyb Department of Computer Engineering, Abdullah Gul University (AGU), Faculty of Engineering, Barbaros Mahallesi, Erkilet Bulvari, Kocasinan, Kayseri, Turkey

27282930313233343536373839

a r t i c l e i n f o

Article history:Received 6 August 2013Received in revised form 29 November 2013Accepted 12 June 2014Available online xxxx

Keywords:Smart GridCloud ComputingSmart Grid and Cloud ComputingarchitectureCloud Computing based Smart Gridapplications and projects

40

a b s t r a c t

A reliable and efficient communications system is required for the robust, affordable andsecure supply of power through Smart Grids (SG). Computational requirements for SmartGrid applications can be met by utilizing the Cloud Computing (CC) model. Flexibleresources and services shared in network, parallel processing and omnipresent accessare some features of Cloud Computing that are desirable for Smart Grid applications. Even-though the Cloud Computing model is considered efficient for Smart Grids, it has some con-straints such as security and reliability. In this paper, the Smart Grid architecture and itsapplications are focused on first. The Cloud Computing architecture is explained thor-oughly. Then, Cloud Computing for Smart Grid applications are also introduced in termsof efficiency, security and usability. Cloud platforms’ technical and security issues are ana-lyzed. Finally, cloud service based existing Smart Grid projects and open research issues arepresented.

� 2014 Published by Elsevier B.V.

41

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

1. Introduction

The Smart Grid (SG) is used by electric power utilities totrack and control power usage of consumers. In SGs, thegovernance of energy usage is done in real time with theability of smart meters’ bidirectional communication [1].A more reliable and secure communication is guaranteedwith the SG’s distributed energy management featurewhich is called as load balancing. Electric power utilitiesachieve preferable operation and management of theirelectric power systems by monitoring their energy usage.When consumed energy reaches peak levels, signals aresent to consumers to reduce energy consumption. In thisway, the SG balances its energy load [2]. Entire powersupply system and protection devices are monitored by

72

73

74

75

76

77

control centers for providing security of SG’s load balanc-ing system during communication. Cloud Computing (CC)is used to perform this communication process betweensubstations and power supply companies’ power plants.Built-in redundancy is utilized to increase the reliability,security and robustness of this communication [3]. In thiscontext, scalable platforms are needed to run many SGapplications when data intensity is high. Over the time ofthe day, the resource requirement varies as the utilizationdifferentiates between day (peak operation) and night(lower level operation). CC platforms can be utilized forobtaining scalable, elastic, secure, robust and sharableresources in order to build and operate a functional SGarchitecture [3].

Utilities and consumers take the security and privacy oftheir data very seriously. This affects the acceptance of SGsprovided by cloud platforms, i.e. the privacy issues for theusers should be addressed by the utilities [4,5]. CCplatforms chosen for SG applications should realize highassurance in their communication systems. There are someperformance issues related to the use of cloud platforms for

doi.org/

Page 2: Cloud Computing for Smart Grid applications

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

2 M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

SG applications as well, e.g. the requirement for supportingreal time services to give rapid response to consumers.Internet congestion and server failure are the main con-straints in this respect [6]. Consistency and fault toleranceservices are necessary for cloud systems. In order to ensurethese features, some consistency models such as databaseguarantees, replication behavior of state machine and vir-tual synchrony must be applied to cloud platforms. Animportant advantage of cloud systems for SG applicationsis their highly qualified Internet routing capability that issupplied by providing multi-path Internet routes betweenaccess points and cloud services. In this manner, connectionlosses are prevented and communication is reliablyachieved between the SG and cloud hosted services.

The next generation computing paradigm, provided byCC, satisfies the requirements of SG applications [7]. Cloudproviders facilitate CC and offer services with their hugeservers for computations and with their big data centersfor storage. Many resources shared in the network, suchas software and information, are provided to the powergrid utility’s devices through CC. Therefore, it is preferablefor many SG applications to use CC for information man-agement and distributed energy management.

There have been several studies on how SG applicationscan exploit CC to increase their reliability and perfor-mance. In the study by Simmhan et al. [8], a SG’s demandresponse is optimized by using CC. This is achieved by CCwith a flexible and scalable model of Cloud virtualmachines. These Cloud virtual machines perform computa-tions to determine the availability of resources to be usedon demand and to be discharged when not in use. Also,redundancy is achieved for critical SG applications by theseCloud virtual machines by adding extra virtual machines toduplicate computations and replicate the data. In the workby Rusitschka et al. [9], a different CC model is proposed forreal time data retrieval and parallel processing for SGapplications. In another research, conducted by Bai et al.[10], CC provides efficient and secure storage managementfor a Smart Grid condition monitoring application. CC alsooffers many other advantages to a SG in terms of afford-ability and scalability. Kim et al. offered a CC baseddemand response architecture which aims at giving fastresponse to customers by providing direct communicationbetween consumers and utilities [11]. Grid aware CC rout-ing algorithms, which solve service request routing prob-lems, are implemented by Mohsenian-Rad et al. [12],Fayyaz et al. [13] and Alcaraz and Lopez In [14], the authorsfocused on addressing the security and reliability issues incombining SG applications with CC. In addition to researchconducted on the application of CC for SGs, there are alsosome products, already in the market, implementing SGapplications utilizing CC. Hohm, Microsoft’s energy man-agement tool, is hosted on a cloud platform proposed tobe used by special residential buildings [15]. Proprietarypower saving suggestions are procured by Hohm [15].Google’s PowerMeter is another tool utilizing CC for SGapplications and was ended in September 26, 2011 [16].It is a scalable platform and facilitates monitoring theenergy usage of consumers. There are also many otherapplications for testing and observing the performance ofCC on SG applications [17–19]. Some of these applications

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

are already in use and some are still being researched. Allthese studies are summarized in Table 1.

The remainder of this paper is organized as follows. InSections 2 and 3, the SG and CC architectures are pre-sented, respectively. In Section 4, opportunities and chal-lenges to apply CC in SG is discussed. In Section 5, theuse of CC for SG applications is analyzed in technical andsecurity perspectives. In Section 6, an overview of CC basedSG applications and projects are given. Open researchissues in CC for SGs are presented in Section 7. Finally, thispaper is concluded in Section 8.

2. The Smart Grid (SG) architecture

An electric grid with the information and communica-tions technology (ICT) is called a Smart Grid. In SG, informa-tion about consumers’ electricity consumption behavior iscollected automatically with the use of the ICT [1]. Thishelps increase the efficiency, reliability and performanceof the electric grid. The European Technology Platform ispreparing a SG policy to overcome many challenges in cur-rent electricity supply, in terms of reliability, flexibility,efficiency, load adjustment, peak power cut, permanency,market supply and demand response support [20]. Reliabil-ity is provided by a SG with its features such as the abilityfor fault detection and self-healing. In SG applications, bidi-rectional energy flow allows for flexible network topologywith distributed generation. The demand side managementfeature of the SG ensures efficiency in energy consumption.The load adjustment feature helps balance loads in spite oftheir variations. If a user’s load exceeds an average thresh-old, power can be cut for this user to control electricityusage in high-cost/peak-usage periods.

The SG conceptual model, identified by the NationalInstitute of Standards and Technology (NIST) [21], givesthe characteristics, requirements, operations and servicesthat should be provided by a SG. It also specifies communi-cation ways from top level to lower levels for SG applica-tions. The conceptual model includes seven domains suchas bulk generation, transmission, distribution, customer,service provider, operations and markets [21] as given inFig. 1. The conceptual model begins with bulk generation.In this domain, electricity generation and protection proce-dures are realized. The second domain is the marketswhich perform load balancing by analysing and optimizingenergy pricing to help control energy consumption of cus-tomers. Business processes of energy producers, customersand transmission companies are performed by a serviceprovider, which is the third domain of the SG conceptualmodel [21]. Operations in the network such as monitoringof network operation, network control, fault detection andreporting are realized with the fourth operations domain.Transportation of electricity from sources to distributionare achieved by using the transmission domain. Serviceproviders optimize flows by the agency of the transmissiondomain and connect with customers via the distributiondomain which achieves real time monitoring of electricityconsumption. The last SG domain is the customers who lettheir energy usage be managed. All of these domains makeup the SG architecture and result in many benefits

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 3: Cloud Computing for Smart Grid applications

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

Table 1Related works about how to use Cloud Computing for managing Smart Grid applications.

CC for SG studies Subject

Simmhan et al. [8] and Kim et al. [11] Demand response optimization with cloud platformsRusitschka et al. [9] Increasing SG applications performance with parallel processingBai et al. [10] SG condition monitoring with secure storage managementHohm by Microsoft [15] Providing power savings for SG applicationsGoogle PowerMeter Tool [16] Monitoring real time energy usageMohsenian-Rad et al. [12] A routing algorithm that solves SG routing problems with CCFayyaz et al. [13] and Alcaraz and Lopez [14] Obtaining more secure systems for SG applications with CC

M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx 3

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

including efficiency, low cost, fault tolerance and renew-able energy generation.

3. Cloud Computing (CC) architecture

The usage of resources in the manner of a service overthe network is called Cloud Computing (CC) [22]. CC hasmany types such as Infrastructure as a Service (IaaS), Plat-form as a Service (PaaS), and Data as a Service (DaaS). [23].Implementation and maintenance costs, and system com-plexity of CC are reduced with the utilization of informa-tion technology. With CC, computations are achievedover the Internet. Resources such as software and informa-tion are shared through the network and retrieved by com-puters and devices on demand.

Distribution of services to a large number scatteredcomputers is the main principle of CC [23]. Thus, compa-nies or systems such as the SG, which use CC, can use theavailable services easily as they need. CC has an EnterpriseData Center which enables to shift resources to meet appli-cations’ requirements and provides access to all storagesystems when needed. On a CC platform, there may be alsoother resources such as firewalls used for security, networkdevices for increased performance and storage area net-works to enhance capacity.

The SG offers many features and applications to con-sumers, however it needs to be improved to handle moresecure, efficient and scalable systems. This can be carriedout by using the power of CC. Operations can be done atlow cost with CC because sharing and automation arewidespread within these systems. Also, real time responseis very important for SG applications for giving immediatedemand response. In cloud platforms, when a clientrequest comes to the cloud operation system, a responseis sent to the client in real time. In addition, CC providesa power efficient self-healing system which is crucial forSG applications to recover from faults and give instantresponse to customers. Communication in the SG isachieved via the Internet, therefore there should be noInternet outages to provide consistent transmission. Thisis handled in CC by assigning two or more IP addressesto a client which is called multi homing [6].

CC has many characteristics that can yield improved SGapplications. These CC characteristics are listed below:

� Reconstruction of SG technological infrastructure isprovided with the agility characteristic of CC [20].� Communication between the machine and cloud soft-

ware is done via CC application programming inter-face (API) [20].

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

� Public cloud delivery model provides lower cost for SGcustomers.� Any device by a consumer/customer that needs to

access the systems can do this from anywhere via theInternet. This is the device and location independencefeature of CC [23].� Maintenance and virtualization are other properties of

CC. Installation is not required for running applicationsand performing computations. This provides easyaccess to CC services from anywhere and at anytime.Servers and storage devices can be shared and carriedeasily from one server to another using the virtualiza-tion property of CC [23].� Large number of users use shared resources, which are

located in a pool. This is enabled by the CC multitenan-cy characteristic. In this way, infrastructure is central-ized with lower cost, without needing extra deviceload capacity and utilization increase [10].� CC provides disaster recovery capability and this

assures reliability [24].� Some architectures are constructed for increasing sys-

tem performance in CC platform by using web services[24].� Reliability is improved by using private cloud platforms

which prevents connection losses [25].

Characteristics of CC, which are summarized in Fig. 2,are suitable for SG applications in terms of security, reli-ability, scalability and performance. Therefore, CC has beenalready used in many SG applications, as described in Sec-tion 2.

4. Opportunities and challenges to apply CC in SG

SG can benefit from all aspects of CC, however there aresome barriers to the adoption of CC by SG utilities.Although these barriers, real-time computing and storagecapacity are required for the SG applications immediately.Therefore, CC is the best and simplest way to meet the SGrequirements in spite of its challenges. In this respect, thissection investigates opportunities and challenges in theintegration of the CC technology within the SG for efficientSG management.

4.1. Opportunities to apply CC in SG

Power industry is interested in CC mainly for businessreasons, i.e. the increased efficiency, reduced price,improved robustness, higher security and scalable capacityare attractive features of the CC in performing the SG

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 4: Cloud Computing for Smart Grid applications

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

Fig. 1. Smart Grid conceptual model.

Fig. 2. Cloud Computing characteristics.

4 M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

capabilities [26]. CC offers low cost computing with respectto older models. Furthermore, its robustness is intrinsicallyprovided with the geographic replication of services. In thisway, when power outages or failures occur in a region, areplicated service immediately starts running. Security inCC is guaranteed with the automatic management of cloudservices which provides easier and better protectionagainst attacks [27]. Capacity of CC is high with the used

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

data centers, and redeployment of services in CC ensureselasticity by shifting loads [28]. All of these advantages ofCC can be used in SG applications. In this respect, driversto use the CC in a SG are shown in Fig. 3 and listed below:

� Scalability: Early SG applications are derelict becauseof the scalability problem for SG components that aredeployed on a large scale. CC solves this scalabilityproblem by deploying storage devices geographicallyand expanding them vertically or horizontally [29].Therefore, the needs of a SG, such as new devices,and data storage capacity, become unnecessary whenCC is used. In this way, SG utilities can react to the mar-ket changes including new state of the art technologyproduct, expeditiously when they have data intensive[30].� Cost Efficiency: Electric utilities use the SG network to

switch from coal and nuclear plants to renewableenergy sources such as solar, wind farms and hydro-electric. In this network, all devices are connected toeach other and send status information to utilities tobe controlled by them. Also, information exchange isdone to check power generation by producers and con-sumption by consumers. This information exchange isprovided at low cost over the Internet by cloud plat-forms and dedicated lines are used for the SG [30].� Central Data Storage: SG applications are high perfor-

mance computing (HPC) applications that need specialcomputing hardware and the ability for parallel pro-cessing. However, these hardware devices are veryexpensive. Sufficient storage and performance can beprovided by a single cloud data center with lower costcompared to deploying special computing hardware.

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 5: Cloud Computing for Smart Grid applications

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

400

M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx 5

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

Therefore, HPC applications such as the SG migrate tothe Cloud Computing platform to deal with the afford-ability issue [31]. This also helps with the set up inthe communication standards in the SG, easily. Ubiqui-tous network access in the cloud also guarantees theaccess of everyone to the cloud and procure interpret-ability between the SG systems. A common communi-cation platform that is offered by the cloud providesdata flow in SG and avoids the use of multiple middle-ware software and interfaces to access the data by SGsystems. Data consistency is also supplied with stan-dardization of data formats on one central platform[30].� Security: Data security and privacy are the most crucial

issues for the SG environment, and therefore a detailedanalysis of the security issues of CC for the SG environ-ment are presented in Section 5.2. In this respect, a pri-vate cloud environment can be used in a SG to provideprivacy, access rights, data encryption, etc. This can beachieved if a service level agreement is done with thecloud provider. Thus, utilities can provide reliance ontheir own by using different ways and CC ensures moresecurity for SG applications with ironclad barriers whenutilities have much more experience to meet require-ments of SG applications. In CC, multiple applicationsare managed and run in a single data center. With theseironclad barriers, users of the same cloud cannot seeeach others’ data and traffic in this shared environment[32].� Real-time Response: Huge amounts of data, such as

energy control/consumption and market data, is pro-cessed synchronically by CC with its distributed dataprocessing centers which provides a scalable load bal-ancing technology in the SG. Control systems in a SGneed the real-time response feature of CC to give rapidreaction against an outage. However, Advanced Meter-ing Infrastructure (AMI) also needs low delay for trans-

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424Fig. 3. Cloud Computing enhancers to use them in a Smart Grid.

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

ferring and displaying control signals and pricinginformation for demand management in the grid envi-ronment. This indicates that CC provides opportunityto monitor, process and verify coming data streamsfrom many SG sources in real-time through its storageand processing capabilities. Using CC, time criticalapplications of a SG is efficiently realized and notaffected from changing conditions [31].

The use of CC for SG applications enables new servicesand business models. However, a SG application has somerequirements that must be addressed by a CC design andthere are some challenges in using CC for SG. These chal-lenges are discussed in Section 4.2.

4.2. Challenges in using Cloud Computing for Smart Grids

The current espousing of CC is also associated withsome challenges contrary to the motivation of applying iton SG systems because SG utilities still have negativethoughts about CC’s authenticity. This can be challengesahead regarding inefficiencies for SG and therefore, whiledesigning CC for SG systems, these challenges must be con-sidered and analyzed carefully. On that note, major chal-lenges of applying CC for SG applications can be outlinedas follows.

� Location of data: Cloud servers are placed in any loca-tion, so location of these servers that store and processSG applications are not known by the business enter-prise. This is very critical issue to meet the require-ments of data management in SG. Therefore, definingthe data location by Cloud Service Providers (CSPs)has a vital importance for the security of SG applica-tions [33].� Mixing of data: CC enables a model to access the appli-

cations through a location independent resource pool.There are many multi-user applications in CSPs how-ever, security and scalability of them is an open issuefor enterprises. Therefore, some security methods suchas data encryption algorithms must be applied on CSPsfor reliability and confidentiality in SG applications[33].� Inefficient cloud security policy: Some CSPs apply

weaker security policies than others. These differencesmay be specific to utilities, therefore they may causedisagreements between SG utilities. Utilities can solvethis problem by putting service level agreements intoeffect between each others to provide required securitylevels for SG applications [30].� Term of agreement: If contract agreement includes

commercial papers that posses stored data in CC, SGutilities can pay huge amount of charge to CSPs for theirrequested data after service level agreement end date[33].� Dependence of CSP’s Application Programming Inter-

faces (APIs): Many applications in CC are implementedby Cloud Service Providers and they are compatiblewith the utility specific APIs. Therefore, passing of SGservices in CC from one CSP to another CSP becomes dif-ficult and takes longer time [33].

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 6: Cloud Computing for Smart Grid applications

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

442

443

444

445

446

447

448

449

450

451

452

453

454

455

456

457

458

459

460

461

462

463

464

465

466

467

468

469

470

471

472

473

474

475

476

477

478

479

480

481

482

483

484

485

486

487

488

489

490

491

492

493

494

495

496

497

498

499

500

501

502

503

504

505

506

507

508

509

510

511

512

513

514

515

516

517

518

519

520

521

522

523

524

525

526

527

528

529

530

531

532

533

534

535

536

537

538

539

540

6 M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

� Compatibility: CC does not comply any audit require-ments. This is the most critical issue that must beovercome by CC for meeting SG auditing compliancerequirements. However, CC has many challenges dueto location of data, inefficient security policy, etc.Therefore, it is difficult for CC to become compatiblewith auditing requirements including privacy laws[34].� Redundant Data Management and Disaster Recovery:

Recovery in emergency situation is the biggest concernof SG utilities because CC distributes data to multipleservers in different geographical areas. Therefore,enough reliability cannot be provided by CC for SGapplications when data in a certain time is not defined.In the current situation, SG utilities know the location oftheir data and access it eventually when a disasterrecovery happens. However, in CC system, CSPs can out-source benefits, services and also recovery processesfrom other parties and this situation causes a compli-cated problem when data is not hold by the main CSP[34].

SG utilities that are under pressure have to enhancetheir practices to deal with high workload. However, veryfew of these utilities aware of safety critical events despitethe SG applications’ authentication, accuracy, availabilityand compatibility requirements. Therefore, it is importantfor the SG utilities to comprehend their current risks andCC challenges that are listed above while designing andimplementing CC on the SG current system. All of thesechallenges and opportunities that is described in Section4.1 are shown on the right side and left side respectivelyin Fig. 4.

5. Analysis of Cloud Computing for Smart Gridapplications

This section analyzes the integration of the CC technol-ogy with the SG. Based on the findings in the previous sec-tions, this section presents the technical and securityanalyzes of CC for SG applications, and shows how CCcan be used in SG applications meeting the securityrequirements.

5.1. Technical analysis of CC for SG applications

Three levels of services are offered to SG utilities by CC.Devices and other utilities such as operating system, stor-age device and database are deployed on a cloud platformand are presented as a SG service according to demandfrom SG customers. As described in Section 3, all of theseCC SG services are divided into three categories as SaaS,IaaS and PaaS, explained as follows:

� Software as a Service (SaaS): One to many applicationdelivery to customer is provided by the SaaS model[26]. This means that only the SG customer can accessthe service that is installed on the utility’s hardwarevia an Internet connection. Customers get permissionto access the services by using their software licensesand, therefore, they pay for each service that is used

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

[26]. In this way, only authorized users can access theservices through their installed APIs. This providessecurity, reliability and efficiency to SG systems.� Platform as a Service (PaaS): Service provider provides

the development environment if required in this servicemodel. Some of the SG utilities can use this model ifthey do not want to invest in the environment or whenthey want to especially focus on the functionality of ser-vices. In this way, concentrate applications can be builtby SG utilities without considering development envi-ronment [33].� Infrastructure as a Service (IaaS): In this model, infra-

structure can be offered as a service by CC to SG utili-ties. CC platforms can share or devote infrastructureto SG utilities who pay for their hardware usage. Com-putational and storage capabilities are provided by thismodel with the CC virtualization concept. IaaS can runSG applications that need high performance by han-dling workloads. Therefore, using this service modelcan be efficient for SG utilities. IaaS performance canalso be increased significantly if SG utilities outsourceCC, resources and the infrastructure from other parties[35]. In this way, CSPs become only responsible for itsmaintenance and repair, and disaster recovery can behandled immediately. Scalability is also one of theadvantages of this model that is useful for meeting aSG’s huge demand response requirements by easilyadding new data storage devices as the demandincreases [33].

CC offers different deployment models for the imple-mentation of SG services. There are three cloud deploy-ment models that are public, private and hybrid. SGutilities must select the most appropriate model accordingto the requirements of their SG services. In this respect, inTable 2, all these models are explained and rated in termsof their usability in SG systems.

� Public Cloud: This cloud deployment model is the pri-mary model of CC. In this model, users pay per use ofSG services. There is not any limitation about whichuser can or cannot use cloud service because it is a pub-lic cloud. Service providers can make different offers,therefore SG services can be charged or not chargedbased on the offered conditions. Cloud Provider man-ages the cloud in the SG and users access the SGthrough the Internet [36]. All the services in this cloudare standardized to meet comparability requirementsof SG applications [37].� Private Cloud: This is an internal deployment model

that works like a private network. However, it can differdepending on the SG application’s requirements. If abasic private cloud is used in a SG, each SG utility hasits own data center and provides services by itself. Thus,high security, reliability and confidentiality are ensured.But, this model prevents other utilities from accessingservices and if an interrelationship is required betweenSG services that are located in different utilities, it is dif-ficult to give access permission to utilities. This problemcan be solved in two ways; one of them is by letting anexternal service provider realize the operation of the

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 7: Cloud Computing for Smart Grid applications

541

542

543

544

545

546

547

548

549

550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568

569

570

571

572

573

574

575

576

577

578

579

580

581

582

583

584

585

586

587

588

589

590

591

592

593

594

595

596

597

598

599

600

601

602

603

604

605

606

607

608

609

610

611

612

613

614

Fig. 4. Opportunities and challenges of Cloud Computing for Smart Grid utilities.

M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx 7

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

private cloud according to a Service Level Agreement(SLA) without taking data and infrastructure; the sec-ond way is to outsource the private cloud by giving allinfrastructure and its management to another serviceprovider [36].� Hybrid Cloud: SG utilities that take advantage of CC

with a cost efficient way can use the hybrid clouddeployment model. This model combines private andpublic cloud deployment models for SGs by making aSG utility a cloud provider that holds its own data cen-ter and uses a private cloud model. A SG utility pro-cesses, analyze and combines data in the private cloudand builds services. Then, all of these services are pub-lished to all other utilities by using public clouds [36].

These different deployment models described above arescored according to their usability for SG applications inTable 2. They are analyzed to find the best suitable CCmodel to use CC with SGs. Assessments show that publiccloud offers a good solution for SG utilities which need lesscomplex and high standardized services. A private cloud isalso very efficient in terms of security for SG applications,however, it is restrictive for SG utilities due to its internalaccess limitation feature. Although an external servicecloud can perform the cloud operation in a private cloud,it is difficult to integrate all SG utilities with respect toan SLA. Hybrid cloud is another approach for SG utilitiesas discussed above. It provides benefits for utilities in aSG by combining public and private clouds. This CC deploy-ment model is the best model for SG utilities due to itscountrywide scalability feature by giving a dominant roleto CSPs.

As illustrated in Fig. 5, multiple services are provided ina SG cloud based on the SaaS service model that is used tocharge customers by a monthly fee. The IaaS model is alsoused for hosting data storage and processing power. Thecloud provider provides services by using the PaaS modelthrough its data center that classify data for data storage

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

and processing power. Utilities and customers call the ser-vices from the SG cloud and response is sent them via theIaaS model. Inputs such as power consumption data arerequired to call some services, therefore customers andutilities have to send these inputs to subscribe these ser-vices. The data center inside the cloud environment is verymodular and established on a virtualized operating system.There are many CPUs in the clusters, and thus the process-ing time decreases and real time response is achieved.Security is also provided with this hybrid cloud by process-ing, analyzing and aggregating data in the private cloudand publishing the computed services to utilities and cus-tomers through the public cloud.

The state of the art in CC for SG applications is describedabove where data centers with large computation andstorage capacities and the hybrid cloud model are ana-lyzed. Results show that CC presents many advantages thatmust be considered by SG utilities. SG applications can beimplemented with several CC services and deploymentmodels. The main advantages of CC for SG applicationsare scalability, real time response, cost efficiency and secu-rity, which are all the most critical and crucial issues for SGapplications.

5.2. Security analysis of CC for SG applications

Power Grid systems are cyber-physical systems whichcombine the physical electricity infrastructure and thecyber infrastructure. The communication line betweenthe two is however blurred and, as a consequence, opera-tions’ control and consumer applications’ communicationin SG systems have critical vulnerabilities against cyber-attacks. Therefore, some standards must be developed toavoid these attacks for SG applications. However, there isno standard for privacy. Cloud platforms can be used byutilities to provide security and safety for SG applications.Consumers’ information such as theirpower usage data iscollected by smart meters and this data is sent to operators

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 8: Cloud Computing for Smart Grid applications

615

616

617

618

619

620

621

622

623

624

625

626

627

628

629

630

631

632

633

634

635

636

637

638

639

640

641

642

643

644

645

646

647

648

649

650

651

652

653

654

655

656

657

658

659

660

661

662

663

664

665

666

667

668

669

670

Table 2Assessment of the usability of Cloud Computing deployment models in the Smart Grid.

Smart grid requirements Public cloud Private cloud Hybrid cloud

Low complexityCost efficientScalabilityHigh securityCompatibilityEasy access to servicesSG usability

Fig. 5. Cloud Computing hybrid cloud architecture for Smart Grid.

8 M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

in real time in SG systems. To obtain security and privacy,this data is encrypted with each customer’s own key [2].Data sizes and time constraints change according to theSG application and CC provides secure and reliable trans-mission control and access to data and utilities. Cloud plat-forms provide long term data conservation with not onlythe customer’s private consumption data but also withthe energy pricing data. A CC platform assures the reliabil-ity and security for SG services through the distribution ofits data centers globally.

Cloud platforms differ for different applications. Somerun on shared platforms while others operate on privilegedplatforms. Therefore, cloud platforms are severed in threetypes as public clouds, private clouds and hybrid clouds[38]. Public clouds provide services, running on the samehardware, to their customers. In this cloud type, a cloudfabric is used to separate the data of different organiza-tions. Even though public clouds seem efficient, they areunreliable and not secure because of possible cyberattacks. Therefore, they are not suitable for SG applications.On the other hand, private clouds provide more secure sys-tems for SG applications since a single organization uses ahardware alone. Visualization and storage services are pro-vided by a cloud fabric to monitor data access. Hence, SGapplications use private clouds for monitoring and trans-mitting customer data. The third cloud type, hybrid clouds,can also be preferred by SG systems since advantages ofboth public and private clouds are enjoyed by hybrid

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

clouds [38]. With stable work load, hybrid clouds workwith private clouds for reliability. However, at peak workloads, it switches to operation with public clouds toincrease performance. Therefore, in certain cases, hybridclouds are favored by a SG to meet the customer require-ments for high performance or high security [39,40].

Safety management control is provided by especiallyprivate Cloud Computing for SG applications. In privateclouds, computing is separated from the storage andshared areas of users. The necessity for solving the risksin data access, information management, data insulationand transfer is the main issue for private clouds. Privateclouds overcome this issue with the ability of security con-trol in the operating system level. Information security inthe SG system is guaranteed through the cloud’s authenti-cation and encryption strategy [41]. In this respect, a SGusing the private cloud architecture has five layers thatfacilitate secure SG applications. These layers are identifiedas the grid application layer, the database and middle-warelayer, the cloud operating system layer, the visualizationlayer and the data center layer. The data center layer islocated at the bottom and it is responsible for data storage.The virtualization layer is the second layer and has themain functionality of protecting against unreliable nodefaults [41]. The distribution of the data center layer’sresources to the database and middleware layer is per-formed by the cloud operating system layer. The databasein the database and middle-ware layer is used for the

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 9: Cloud Computing for Smart Grid applications

671

672

673

674

675

676

677

678

679

680

681

682

683

684

685

686

687

688

689

690

691

692

693

694

695

696

697

698

699

700

701

702

703

704

705

706

707

708

709

710

711

712

713

714

715

716

717

718

719

720

721

722

723

724

725

726

727

728

729

730

731

732

733

734

735

736

737

738

739

740

741

742

743

744

745

746

747

748

749

750

751

752

753

754

Fig. 6. Smart Grid private cloud layers.

M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx 9

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

storage of data that comes from the application layer. Theapplication layer includes complex applications whosecomplexity is handled by middle-ware. SG applications,such as fault diagnosis and system monitoring, run onthe application layer. The application layer runs these SGapplications by sending request to the lower layers andretrieving information from these layers in a secure way.All of these private cloud layers are illustrated in Fig. 6.

Another security approach is to use a protection policyfor cloud service based Smart Grid information manage-ment [7]. Any SG system can potentially collapse due tonode failures. Therefore, quality of service and securityfor SG systems must be ensured in cloud platforms. To thisend, in [7] a protection policy manager (PPM) is proposed.The PPM is located in the SG system and ensures an inter-face between the SG system and the CC platform. In the CCplatform, quality of service, privacy and security are forcedby the PPM as SG services. The PPM provides securityaccording to the requirements of SG applications by usingthree different strategies as described below.

� Selection of reliable CC service providers [8]: Provi-sioning of SG information management requirementsare done by the selection of the correct private cloudby the PPM. This results in trustable data storage, trans-mission and computation.� Information and computation ciphering [42]: PPM

encrypts information that is held in CC storage devicesfor providing data security in the SG domain. PPM alsochecks whether data is changed during transmissionand makes necessary corrections if it is altered. Privacycan be achieved by using a homomorphic encryptionscheme which allows for computations over encrypteddata [42].� Enhancing redundancy of data storage and computa-

tion [43,44]: Virtualization technology is developed byPPM to increase redundancy of the data item. Redun-dancy is increased by storing different parts of the dataitem in separate CC service providers and when theredundancy design is made well, the missing parts ofa data item can be recovered.

All of the above features of PPM indicate that using CCfacilitates robust, reliable and secure transmission in SGapplications. Similar to PPM, there are also otherapproaches that help secure the SG by using the CC tech-nology. These approaches are described as follows.

The data access and privacy issues in SG technologies arestudied by the Department of Energy (DOE) and theNational Institute of Standards and Technology (NIST)which publishes standards for cryptographic algorithmsthat must be used by the US government [45–47]. In [45],the key findings are summarized for the data safety, con-sumer access and confidentiality issues in Smart Grid tech-nologies. These provide a detailed overview to assess thestate of existing SG security policies. From these findings,[45] especially focuses on the development of legal and reg-ulatory regimes [45] and the development of proper pri-vacy and security standards, as investigated by the NIST[46,47], to increase the success of security efforts. In [46],the privacy concerns of SG users are dealt with in terms

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

of personal data, personal confidentiality, behavioral confi-dentiality and personal communications confidentiality.Recommendations such as transparent installation of SGtechnologies, providing training and awareness programsfor employees responsible for SG users’ personal informa-tion security are included in the NIST guideline to improvethe privacy of users in the SG [46]. For a detailed risk anal-ysis, the vulnerabilities of the electric grid technology,which adversely affect the operation of the SG, are listedin [47]. These vulnerabilities are categorized in five classessuch as people related vulnerabilities, policy and procedurevulnerabilities, platform software/firmware vulnerabilities,platform vulnerabilities and network vulnerabilities. Theguidelines by the NIST [46,47] and DoE [45] provide consis-tent security mechanism for the SG technology.

Another SG security approach includes using a publickey infrastructure (PKI) and techniques as proposed by[48]. In this study, an integrated solution including PKItechnologies, which are certificate life-cycle managementtools, reliance anchor security and attribute certificates,and trusted computing elements has been implementedto provide the highest level of security for Smart Grids.The aim of using trusted computing elements is to form asecure environment for complex Cloud Computing and

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 10: Cloud Computing for Smart Grid applications

755

756

757

758

759

760

761

762

763

764

765

766

767

768

769

770

771

772

773

774

775

776

777

778

779

780

781

782

783

784

785

786

787

788

789

790

791

792

793

794

795

796

797

798

799

800

801

802

803

804

805

806

807

808

809

810

811

812

813

814

815

816

817

818

819

820

821

822

823

824

825

826

827

828

829

830

831

832

833

834

835

836

837

838

839

840

841

842

843

844

845

846

847

848

10 M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

Internet applications which need extensive deployment ofmobile code such as Flash, PDF, and Java. To this end, in[48], a remedy is proposed with standards that areexposed, adhered and signed by operators and suppliers.All the critical components of a Smart Grid must be cov-ered by these standards to construct a trust managementframework. In this way, secure and more reliable environ-ments can be realized for a Smart Grid.

Integrated Security System (ISS) is proposed by [49] forprotection of the Smart Grid against cyber attacks. ISSincludes three components including manager module,switch & agent module and assessed module. All of thesemodules help increase the security of the SG control sys-tem architecture and legacy control devices by securingthe Supervisory Control and Data Acquisition (SCADA) sys-tem. The layered structure of ISS prevents intruders andoffers scalable, expandable and inter-operable solutionsfor grid security [49].

In [50], a privacy preserving protocol, based on securemulti-party computation (SMC), is proposed for real-timedemand management. Using the SMC computation frame-work for secure communication between multiple partiesvia a secured protocol including homomorphic encryption,the proposed architecture meets the smart meter require-ments such as the protection of the end user’s personaldata, load management, providing a sustainable billingmethod and removing the need of third party applicationsfor security. In this method, computations can be per-formed on encrypted data and thus privacy of data isconserved.

Other studies focus on issues related to the privacy ofcollected smart metering data by using basic cryptographictechniques [51]. They present protocols to aggregate smartmeter measurements [52], and construct authenticationmechanisms to define anonymous smart meter readers[53]. All of these techniques are designed for addressingthe security and privacy challenges in the Smart Grid suchas consumer fraud and malicious hackers [54].

849

850

851

852

853

854

855

856

857

858

859

860

861

862

863

864

865

866

867

868

869

870

6. Cloud Computing based Smart Grid projects andapplications

Electric power systems consist of three subsystems thatare power generation, power delivery and power utiliza-tion. In recent years, CC has been known as a hope-inspiringtechnology that strengthens all these SG subsystems andtherefore, it becomes a crucial component for SG applica-tions. Within this context, many CC based SG projectsincluding Globus [59], EGI-InSPIRE (Integrated SustainablePan-Europe an Infrastructure for Researchers in Europe)[60], Information Power Grid from NASA [61], OpenNebula[62] and TClouds [63] have been implemented and they aresummarized in Table 4. Additionally, existing SG applica-tions run on cloud platforms are presented in this sectionto demonstrate the effectiveness and trustworthiness ofapplying CC in SG. Concordantly, CC architecture for eachapplication varies depending on the SG application require-ments, so other technologies, such as cognitive radio,MapReduce, and Hadoop, are also evaluated in some ofthe CC based SG applications.

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

6.1. Generation scheduling with demand responseoptimization

Real-time consumer power usage tracking is done bypower utilities with smart meters [8]. But, after retrieving,analyzing and processing millions of consumer data, trans-forming them to significant decisions are so much difficultand hard to manage for SG meters. Therefore, differentkinds of solutions such as information and software systemtechniques, which include pattern mining, machine learn-ing, semantic information, distributed stream processingand CC platforms, are used to reduce complexity of theSG events, to give rapid response to customers and to pro-vide scalable and reliable communication environment.This solution is applied in Los Angeles Smart Grid Demon-stration Project that has been already finished and used incity [8]. The goal of this project is that optimizing thepower consumption with managing huge amount of dataand demand upward by combining stream processing,semantic complex event processing and CC platforms withSG systems. In this respect, they propose a system archi-tecture model that is shown in Fig. 7 to achieve SG demandresponse optimization [8]. This model has two layers asshown in Fig. 7. The top layer performs demand responsetasks including in order retrieving real time smart meterinformation, detecting abnormalities in a short period oftime for decreasing latency to give critical response,enriching smart meter data by using semantic information,updating demand forecast according to latest cominginformation and giving targeted response when peak loadhappens by communicating with customers, and the sec-ond layer of the model includes technologies that are usedto realize these tasks. All these technologies inside the sec-ond layer are explained below:

� Scalable stream processing: retrieves SG meter read-ings streaming via communication protocols and whenemergency situation occurs, detects it and gives rapidresponse.� Semantic information integration: combines informa-

tion that is taken from online services with AMI data.� Data mining and complex event processing: uses

some models to estimate a mismatch in supplier anddemand sites.� Machine learning: finds the most efficient technique

for load cutting according to customer response.� Natural language processing: translates a chosen

response into a workable form for sending it to acustomer.� Cloud infrastructure: all tools that are mentioned

above run on cloud platforms that share informationby using Web services with respect to data privacyrules.

6.2. Cloud based smart meter

Bidirectional communications is one of the importantfeatures of the SG. This provides to control devices and theiroperations with smart meters that collect information fromSG users’ devices and check their status. However, if a newapplication needs to be added on this SG application, the

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 11: Cloud Computing for Smart Grid applications

871

872

873

874

875

876

877

878

879

880

881

882

883

884

885

886

887

888

889

890

891

892

893

894

895

896

897

898

899

900

901

902

903

904

905

906

907

908

909

910

911

912

913

914

915

916

917

918

919

920

921

922

923

924

925

926

927

928

929

930

931

932

933

934

935

936

937

938

939

940

941

942

943

944

945

946

947

948

949

950

951

952

M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx 11

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

whole system must be reconstructed [64]. This can beavoided by using the cloud smart meter framework [7]. Sys-tem architecture of this framework is shown in Fig. 8 [7]. Asshown in Fig. 8, all the SG services that perform anadvanced metering application are placed into the smartmeter application cloud. These services are developed,maintained and updated by the utilities inside this cloud.A smart meter accesses these services through a publicinterface and controls the devices with respect to comingresponse from the cloud. For instance, a smart applicationcloud includes a smart heater control service that learnsthe heat balance to equalize billing and warming. A smartmeter requests this service and controls the heat accordingto coming information. If the service provider updates thisservice such as changing the heat balance, the smart meterdoes not need to know this change, it does the same thingwith respect to a service response. This framework providesefficient solutions with these features for the SG AdvancedMetering Infrastructure (AMI) with the ability of scalability,dependency and reliability because all appliances requestsare met from one and shared cloud platform.

6.3. Cloud based Machine to Machine (M2M) communicationsapplications for SG systems

Communication technology is provided by M2M com-munications for ensuring communication between sys-tems and devices without needing humans. Therefore,many SG applications use M2M technology for smartmeters and its energy management systems to interchangeinformation. CC is combined with M2M communicationsbecause of its low cost, efficiency and high performance.In this respect, a SG’s energy management system is sup-ported by M2M with CC. In [55], intelligent cloud basedenergy management system (iCEMS) is proposed. iCEMSgeneral system architecture, shown in Fig. 9, consists ofthree layers: consumer, iCEMS middleware and physicalresources. iCEMS middleware and physical resources arelocated inside the cloud platform to utilize cloud CC meth-ods. In this respect, iCEMS provides four main benefits toSG systems by using these CC features. The first one isthe management of local renewable energy. Integrationof renewable energy with existing SG is difficult, therefore

Fig. 7. System architecture model of de

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

load demand management cannot be done efficiently.iCEMS solves this problem with dynamic load demandmanagement that is performed by its load demand man-ager. The load demand manager includes a demand fore-casting engine and a battery monitor inside the iCEMSmiddleware [55]. Thus, continuous power can be suppliedfor users. The second feature is balancing energy for pro-cessing and storage by selecting suitable energy sourceswith respect to SG service requirements. Therefore, iCEMSuses CC platform to increase energy efficiency by cluster-ing resources efficiently. iCEMS performs CC task with acloud manager that is located inside the middleware forcollecting consumer requirements, measuring energy con-sumption of resources, providing security and managingresources. The third property of iCEMS is that it increasesthe energy efficiency by decreasing monitoring, processingand communication operations of M2M devices. That isachieved by using power monitoring and environmentmonitoring sensors as shown in Fig. 9. These sensorsalways send information about consumed power, deviceprofile, and environment and user profiles, periodically.According to these information, the knowledge repositorythat is located in iCEMS middleware is updated and the sit-uation based adaptive resource allocation information issent by iCEMS to improve energy efficiency [55]. Thefourth feature of iCEMS is that it provides user friendlyenergy management services for increasing energy effi-ciency with user interaction [55]. This offers user specificinformation, location and situation dependent energymanagement services to customers [55].

6.4. Cyber Physical System (CPS) for SG

Cyber Physical System (CPS) is a CC application for thepower grid. The integration of computing power, commu-nication capability and self governing control ability isdone by CPS [56]. SG monitoring applications need to con-trol the environment in real time and CPS facilitates this bycontrolling situations of information, processes, transmis-sions and environment in real time. CPS also provides SGsecurity with Microgrid that is combined to SG systemand is called as Microgrid CPS framework. The systemarchitecture of this framework is shown in Fig. 10. Both

mand response optimization [8].

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 12: Cloud Computing for Smart Grid applications

953

954

955

956

957

958

959

960

961

962

963

964

965

966

967

968

969

970

971

972

973

974

975

976

977

978

979

980

981

982

983

984

985

986

Fig. 8. System architecture of Cloud Smart meter framework [7].

Fig. 9. System architecture of iCEMS [55].

12 M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

the information and power networks are controlled by thisMicrogrid CPS in SG applications using physical and infor-mation processing equipments such as distributed powersupply devices, sensors and servers. All power equipmentsare connected with each other via transmission lines. Asshown in Fig. 10, CPS forms a local area network for theSG communication network and connects with the SG net-work via a CPS router. In this system, the distribution net-work combines all data that are retrieved from the CPSenvironment. This information is analyzed and processedin real-time. User information is also checked by the distri-bution network to legitimate the user. Power distribution,control system, energy storage and load are also allincluded in this CPS local area network and in CPS architec-ture these loads are balanced with respect to three cases.These are adjustable load, interruptible load and sensitiveload. Microgrid performs all of these load adjustments byinteracting with the CPS local area network to retrieve

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

information about the network and gives response tousers’ demand according to data analysis via an actuatornode [56].

6.5. SG condition monitoring with CC platforms

SG systems process large amount of data including realtime information, operating data, test data, etc., and thesize of this data increases every day. Therefore, SG condi-tion monitoring becomes more difficult in terms of reliabil-ity and security. In this manner, [10] proposes the systemarchitecture, shown in Fig. 11, for cloud platforms thathold status information of a SG. This technology providesefficient and real time SG condition monitoring with bigdata. [10] combines different kinds of technologies toensure high performance, efficient and robust SG conditionmonitoring systems. Hadoop is one of the used technolo-gies to increase the productivity by running idle servers.

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 13: Cloud Computing for Smart Grid applications

987

988

989

990

991

992

Fig. 10. System architecture of CPS in Smart Grid [56].

Fig. 11. System architecture of Cloud Computing platform for Smart Grid condition monitoring [10].

M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx 13

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

In this way, hardware utilization increases and equipmentcost decreases because of the reduced number of therequired devices. Another technology that is used for SG

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

condition monitoring is the Hadoop Distributed File Sys-tem (HDFS) that is located inside the cloud platform asshown in Fig. 11. The HDFS is preferred because it is fault

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 14: Cloud Computing for Smart Grid applications

993

994

995

996

997

998

999

1000

1001

1002

1003

1004

1005

1006

1007

1008

1009

1010

1011

1012

1013

1014

1015

1016

1017

1018

1019

1020

1021

1022

1023

1024

1025

1026

1027

1028

1029

1030

1031

1032

1033

1034

1035

1036

1037

1038

1039

1040

1041

1042

1043

1044

1045

1046

1047

1048

1049

1050

1051

1052

1053

1054

1055

1056

1057

1058

1059

1060

1061

1062

14 M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

tolerant and its deployment is realized by using low costhardware. SG applications that have large data sets andneed high throughput access can use the HDFS for effi-ciency [65]. The third technology that is used for [10]’sSG condition monitoring tool is HBase that is a fault toler-ant relational database and used for dealing with big tables[66]. Therefore, [10] uses HBase to deal with large data setsretrieved from SG applications. MapReduce, another toolprovided by Hadoop, is used in the proposed architecturefor parallel processing across huge datasets. It achieveshigh performance with the ability of fault diagnosis andchannel condition monitoring by retrieving data from theonline data grid and the offline state of the equipment datagrid, as shown in Fig. 11, and spreads the operations acrossthe channels [25]. As a result, the CC based SG conditionmonitoring tool provides high performance with MapRe-duce, more security with the HDFS’s fault detection featureand more storage with HBase. Integration of these technol-ogies offers resistant solutions with fault diagnosis to CCbased SG applications, as summarized in Table 3. Hence,it is preferable for a SG to a cloud platform to increase itsperformance, reliability and efficiency [10].

6.6. Dynamic Internet Data Centers (IDCs) operations with SGand CC

In this application Internet Data Centers (IDCs), that arethe parts of a CC platform for computing many operationswith big data, are used for minimizing electricity cost inthe Smart Grid environment [57]. Electricity price in aSmart Grid changes according to demand response, andwhen demand increases, the cost also increases. Therefore,dynamic workload becomes an important subject for bothclients and power suppliers. In this respect, Wang et al.[57] proposes a model for minimizing the electricity costby using dynamic power supply. Their proposed method

Table 3Cloud Computing service-based Smart Grid applications.

CC based SG applications Benefit fe

Generation scheduling with demand response optimization [8] VisualizeCloud based Smart Meter [7] Easy inteiCEMS [55] ProvidingCPS for SG [56] Offer LoaSG Condition Monitoring with CC Platforms [10] Used of HDynamic Internet Data Centers Operations with SG and CC [57] Reduce e

algorithmNET-AMI with the Integration of Cognitive Radio and CC [58] Providing

cognitive

Table 4Cloud Computing for Smart Grid projects.

SG and CC Projects Domain Mission

Globus [59] SG Resolving distributedEGI-InSPIRE [60] SG Constitution of Europ

(DCI)Information Power Grid from NASA [61] SG High Performance ComOpenNebula [62] CC CC management withTClouds [63] CC Constructing cloud pl

secure and resilient o

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

is based on two operations. One of these operations is toachieve electricity cost minimization in the SG environ-ment with IDC operators that manage dynamic workloadby becoming price maker instead of being price taker inthe proposed system. The second operation is by designingand using an algorithm, called Corrected Marginal Cost(CMC), for solving the optimization problem to procuremarginal cost by distributing workload between IDCs.

Wang et al. [57] firstly formulates the energy cost mini-mization problem by deploying IDCs that are inside theseparate electricity market regions and front-end Web por-tals to retrieve user requests. In this respect, when requestsof clients are captured by Web portals, it sends them to aIDC for processing. Electric cost of all these IDCs are triedto be minimized by estimating each IDC machines workloadthat is assigned by front-end Web portal server. In secondphase, marginal cost of each IDCs are computed accordingto proposed algorithm of CMC. This algorithm computesthe marginal cost by comparing each IDCs cost. However,marginal cost shows that total cost always changes due todemand change in electricity usage. Therefore, CMC algo-rithm decreases the power consumption of IDC that hasbig marginal cost and increases the power consumption ofIDC that has low marginal cost. In this way, total costdecreases and electricity cost minimization is achievedwith handling interaction between SG and IDCs, adaptively[57]. However, dynamic workload and variable electricprices cause instabilities in IDCs. Therefore, Rao et al. [67]propose a scheme and model to minimize the operation riskand design the most suitable algorithm to provide quality ofservice against irregular electricity market and overcomeuncertainties of IDCs under SG environment.

Rao et al. [67] firstly study with a single IDC location tohandle instabilities. They propose electricity cost and riskminimization formulas with a new metric unit to measurethe electricity cost. In the second phase, they study the use

ature for SG by CC

d resource pool to store all data in one placegration of new applications to Smart Meter

efficiency, high performance with using renewable resources for SGd balancing and increase securityadoop, HDFS, HBase, MapReduce to enhance SG performance

lectricity price with dynamic workload by using IDCs and CMC

cost-efficient platform for AMI meters by using CC energy services andradio services

resource sharing with a one source frameworkean Grid Infrastructure (EGI) for Distributed Computing Infrastructure

puting, Data Management in Large-Scaledeveloping scalable, highly adaptable software

atforms with the ability of low cost, reliable and scalable for providingperations

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 15: Cloud Computing for Smart Grid applications

1063

1064

1065

1066

1067

1068

1069

1070

1071

1072

1073

1074

1075

1076

1077

1078

1079

1080

1081

1082

1083

1084

1085

1086

1087

1088

1089

1090

1091

1092

1093

1094

1095

1096

1097

1098

1099

1100

1101

1102

1103

1104

1105

1106

1107

1108

1109

1110

1111

1112

1113

1114

1115

1116

1117

1118

1119

1120

1121

1122

1123

1124

M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx 15

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

of distributed IDC locations. Energy usage problem of IDCsare tried to be solved by modeling risk minimization prob-lem and with an hedging algorithm. A hedging algorithmprovides the certainty by solving the deregulation problemthat is the variation of electricity price change at each timeat different IDC locations. [67] formulates this deregulationof IDC locations at time t with a vector and provides hedg-ing with buying electricity from power market before elec-tricity price fluctuations and dynamic workload happen tominimize operation risk. However, an IDC operator needsto know how much electricity to buy which is decided withan optimal hedging algorithm. Proposed hedging algorithmfigures the amount of electricity to buy for each IDC loca-tion by specifying the time interval that is used to deter-mine for how long the electricity is bought. These aredefined with the hedging algorithm which computes thevariance and covariance of price and load for each IDC loca-tion and in the end calculates electricity cost of each IDC.As a result, Rao et al. [67] test their systems’ suitabilityby using real work loads and by retrieving real energy pricefluctuations. According to test results, Rao et al.’s [67] rec-ommended scheme becomes successful to reduce IDCsoperations’ risks by solving instabilities of electricity price.This solves SG applications’ problems that mostly occurdue to surging power usage.

6.7. NET-AMI with the integration of cognitive radio and CC

Netbook advance metering infrastructure (NET-AMI) isone of the applications which uses a Cloud Computing datacenter to provide central communication and optimize thenetwork infrastructure. Cost efficient platform is provided

Fig. 12. NET-AMI cloud data center system architectur

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

for AMI meters by Net-AMI with wireless transceiver thatis used to access cloud data center’s energy services, cogni-tive radio services and wireless communication servicesthrough cognitive radio channels [58]. This low cost plat-form is achieved by Net-AMI by reutilizing the cell towersand using low frequency bands. In this way, deploymentof Net-AMI becomes easy and speedy while it performscommunication with the metropolitan wide network. Italso provides communication based on universal wirelessstandards and protocols and is attenuated to oncomingstandards by improving software. In addition, Net-AMI pro-poses a persistent communication against power line fail-ures during power information transmission betweenutilities and hosts. All of these features of NET-AMI are per-formed with an efficient wireless cloud data center systemarchitecture that enables communication between utilitiesand NET-AMI via cognitive radio transmission.

Fig. 12 shows the procedure about how NET-AMI per-forms communication between a utility and the Home AreaNetwork (HAN). In this infrastructure, instead of registeringNET-AMI to a Wireless Service Provider, wireless transmis-sion between NET-AMI and the utility is enabled by adopt-ing a new universal interface style. Wireless connectivitybetween utility and NET-AMI is supplied by Cognitive radiothrough deployment of cognitive radio antenna and cellularprovider antenna on the base transceiver station on boththe utility and NET-AMI sites. This reduces the infrastruc-ture cost and path loss because existing base transceiverstations are used and the height of cognitive radio antenna,that is important to make reliable communication, remainssame [58]. Communication between utilities, NET-AMI andcloud data center is performed by cognitive radio that

e with cognitive radio transmission feature [58].

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 16: Cloud Computing for Smart Grid applications

1125

1126

1127

1128

1129

1130

1131

1132

1133

1134

1135

1136

1137

1138

1139

1140

1141

1142

1143

1144

1145

1146

1147

1148

1149

1150

1151

1152

1153

1154

1155

1156

1157

1158

1159

1160

1161

1162

1163

1164

1165

1166

1167

1168

1169

1170

1171

1172

1173

1174

1175

1176

1177

1178

1179

1180

1181

1182

1183

1184

1185

1186

1187

1188

1189

1190

1191

1192

1193

1194

1195

1196

1197

1198

1199

1200

1201

1202

1203

1204

1205

1206

1207

1208

1209

1210

1211

1212

1213

1214

1215

1216

1217

1218

1219

1220

1221

1222

1223

1224

1225

1226

1227

1228

1229

1230

1231

1232

1233

1234

1235

1236

1237

1238

1239

1240

16 M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

senses the spectrum in the cell and finds unused bands. Thecognitive radio’s sensed information is sent to cloud datacenter through fiber, and cloud data center opens all ser-vices, i.e. cognitive radio service, waveform service, proto-cols service, security service, microgrid information packetand air-interface service and microgrid energy optimizationservice [58]. These services are used by the cloud data cen-ter to prepare and send response to NET-AMI by accessingcognitive radio antenna through radio over fiber. NET-AMIrealizes some tasks such as getting information from HANaccording to coming request and sending response to clouddata center with cognitive radio antenna through radio overfiber. Cloud data center analyzes this coming data fromNET-AMI and prepares a control signal to send NET-AMIin order to use control devices in HAN [58].

7. Open research issues in CC for SGs

Many projects and applications exist for the purpose ofusing CC to service the information management in the SG.However, there are still some open research issues thatmust be solved to realize this aim. These open researchissues are listed below.

� Security Framework for SG Applications: Security is amajor issue for electric companies. If the data in thecloud is compromised, cloud companies can suffer fromthis situation. This risk increases when hackers obtrudeinto the internal system. How to provide securityagainst these hackers is a challenging question for cloudservices. Therefore, a security framework based on theSG authentication is needed to improve security whenCC is applied for SG applications. This authenticationmechanism can work by blocking non-authorizeddevices. Device blocking can be achieved with cloudplatforms, and thus only SG users can use the SG appli-cations and others cannot access these applications.This can improve a SG’s performance and reliability.This framework can also increase security when datalocated in the private cloud is moved to the public stor-age space with authorization control for the stored dataand separate access levels assigned to each user andsoftware agent [36].� Increasing Robustness: There is a huge amount of data

and information flow between SG utilities. Therefore,when failures occur in these utilities, the network con-nectivity is lost and, as a result, all data and analysiscenters fail in their operations. If such a disaster occurs,the cloud provider needs to have an efficient recoverymechanism to restore all the data. Robustness of cloudplatforms must also be increased for critical SG applica-tions that need to share information trustfully in real-time and large scale. This can be achieved by using anadvanced distributed communication framework whichtraces state of the SG network [36].� Defining Communication Protocols and a Model for

Network Utilization: The coupling between the energycomponents and the CC system must be provided. Thereare massive amount of objects and all of them need syn-ergy between each other. However, in the current sys-tem it cannot be provided with the traditional

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

methods. Therefore, protocols should be defined to pro-vide interpretability between cloud platform and SGsystems. In this way, CC service providers and userscan efficiently work with each other. In addition, net-work utilization must be also increased with a modelthat provides only the subscribers, who needed, canaccess the SG services and remaining of them areblocked to access.� Economic Data Centers and Large Scale Cloud Plat-

forms: Large amount of electric power is consumedby cloud data centers. Cloud platforms are importantto support many SG applications. Therefore, energy effi-cient cloud platforms must be designed to reducepower consumption for SG applications and carbonemission for the environment. This can be achieved bystrengthening cloud virtual machines according to theutilization of resources. In this respect, a CC model mustbe constructed to strength these virtual machines byreallocating them dynamically to a new place whereenergy is cheaper according to the required CPU perfor-mances of SG applications. Global cloud platforms mustbe also built to increase SG applications scale in market.This cost efficient model must also increase scalabilityand improve resource utilization by eliminating redun-dancies and by adjusting resource usage according toSG applications’ requirements.� Timely Demand Response: The requirements of SG

applications for timely demand response must be metwith cloud platforms. SG applications need optimizedand adaptive/real time demand response management.Therefore, cloud platforms require a scheduling mecha-nism and a distributed infrastructure to increase com-munication speed and to provision time critical SGapplications. This can be achieved by distributing Cloudvirtual machines to locations where there is highdemand.� Efficient Streaming with Clouds: Stream operations are

needed for SG audio and video applications using CC.There is a heterogenous network in the SG domain andefficient streaming must be supported in this environ-ment. For this reason, private and public clouds needstream processing for data integration. A dynamicallyadjustable multimedia streaming (DAMS) algorithm,which adjusts encoding method dynamically for multi-media applications with respect to bandwidth availabil-ity and power [68], can be applied inside cloud platformsfor decreasing load and reducing power consumption.

These are the open research issues for cloud platforms.All these issues raised should be addressed to realize moreefficient and reliable SG applications.

8. Conclusion

In this paper, the SG and CC architectures, and relatedworks on SG applications with cloud platforms arereviewed. Opportunities and challenges of cloud platformsfor SG applications are described. Cloud platforms are ana-lyzed from technical and security perspectives, and theircompatibility with SG systems is investigated. Cloud

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 17: Cloud Computing for Smart Grid applications

1241

1242

1243

1244

12451246124712481249125012511252125312541255125612571258125912601261126212631264126512661267126812691270127112721273127412751276127712781279128012811282128312841285128612871288128912901291129212931294129512961297129812991300130113021303130413051306130713081309131013111312131313141315

1316131713181319

M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx 17

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

service based SG applications and projects are presented tomake the case for the suitability of CC for SG applications.Finally, some open research issues are described.

132013211322132313241325132613271328132913301331133213331334133513361337133813391340134113421343134413451346134713481349135013511352135313541355135613571358135913601361136213631364136513661367136813691370137113721373137413751376137713781379138013811382138313841385138613871388138913901391139213931394

References

[1] V. Gungor, B. Lu, G. Hancke, Opportunities and challenges of wirelesssensor networks in smart grid, IEEE Trans. Ind. Electron. 57 (2010)3557–3564.

[2] Y. Simmhan, A. Kumbhare, B. Cao, V. Prasanna, An analysis ofsecurity and privacy issues in smart grid software architectures onclouds, in: IEEE International Conference on Cloud Computing, IEEE,2011, pp. 582–589.

[3] W. Wang, A. Rashid, H. Chuang, Toward the trend of cloudcomputing, J. Electron. Comm. Res. 12 (2011).

[4] A. Beloglazov, J. Abawajy, R. Buyya, Energy-aware resource allocationheuristics for efficient management of data centers for cloudcomputing, Future Gener. Comput. Syst. 28 (2012) 755–768.

[5] V. Chang, G. Wills, R. Walters, W. Currie, Towards a Structured Cloudroi: The University of Southampton Cost-Saving and UserSatisfaction Case Studies, 2012.

[6] K. Birman, L. Ganesh, R. Renesse, Running smart grid controlsoftware on cloud computing architectures, in: Workshop onComputational Needs for the Next Generation Electric Grid, Ithaca,New York.

[7] X. Fang, S. Misra, G. Xue, D. Yang, Managing smart grid informationin the cloud: opportunities, model, and applications, IEEE Network26 (2012) 32–38.

[8] Y. Simmhan, S. Aman, B. Cao, M. Giakkoupis, A. Kumbhare, Q. Zhou,D. Paul, C. Fern, A. Sharma, V. Prasanna, An informatics approach todemand response optimization in smart grids, Natural Gas 31 (2011)60.

[9] S. Rusitschka, K. Eger, C. Gerdes, Smart grid data cloud: a model forutilizing cloud computing in the smart grid domain, in: First IEEEInternational Conference on Smart Grid Communications(SmartGridComm), IEEE, 2010, pp. 483–488.

[10] H. Bai, Z. Ma, Y. Zhu, The application of cloud computing in smartgrid status monitoring, Internet Things (2012) 460–465.

[11] H. Kim, Y. Kim, K. Yang, M. Thottan, Cloud-based demand responsefor smart grid: architecture and distributed algorithms, in: IEEEInternational Conference on Smart Grid Communications(SmartGridComm), IEEE, 2011, pp. 398–403.

[12] A. Mohsenian-Rad, A. Leon-Garcia, Coordination of cloud computingand smart power grids, in: First IEEE International Conference onSmart Grid Communications (SmartGridComm), IEEE, 2010, pp.368–372.

[13] S. Fayyaz, M. Nazir, Handling security issues for smart gridapplications using cloud computing framework, J. Emerging TrendsComput. Inf. Sci. 3 (2012).

[14] C. Alcaraz, J. Lopez, Addressing situational awareness in criticaldomains of a smart grid, Network Syst. Secur. (2012) 58–71.

[15] M. Hohm, Microsoft hohm Fact Sheet, 2009. Microsoft Corp. <http://www.microsoft-hohm.com>.

[16] Google.org, Google PowerMeter – Save Energy. Save Money. Make aDifference, 2011. <http://www.google.com/powermeter/about/>.

[17] V. Bernardo, M. Curado, T. Staub, T. Braun, Towards energyconsumption measurement in a cloud computing wireless testbed,in: First International Symposium on Network Cloud Computing andApplications (NCCA), IEEE, 2011, pp. 91–98.

[18] M. Bjelica, B. Mrazovac, V. Vojnovic, I. Papp, Gateway device forenergy-saving cloud-enabled smart homes, in: Proceedings of the35th International Convention MIPRO, IEEE, 2012, pp. 865–868.

[19] I. Hong, J. Byun, S. Park, Cloud computing-based building energymanagement system with zigbee sensor network, in: SixthInternational Conference on Innovative Mobile and InternetServices in Ubiquitous Computing (IMIS), IEEE, 2012, pp. 547–551.

[20] J. Popeang, Cloud computing and smart grids, ERP E-Business Appl.Deployment Open Source Distrib. Cloud Syst. III (2012) 57–66.

[21] D. Von Dollen, Report to nist on the smart grid interoperabilitystandards roadmap, in: Prepared by the Electric Power ResearchInstitute for NIST (June 2009), 2009.

[22] B. Ugale, P. Soni, T. Pema, A. Patil, Role of cloud computing for smartgrid of india and its cyber security, in: Nirma UniversityInternational Conference on Engineering (NUiCONE), IEEE, 2011,pp. 1–5.

[23] L. Zheng, S. Chen, Y. Hu, J. He, Applications of cloud computing in thesmart grid, in: 2nd International Conference on Artificial

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

Intelligence, Management Science and Electronic Commerce(AIMSEC), IEEE, 2011, pp. 203–206.

[24] E. Brynjolfsson, P. Hofmann, J. Jordan, Cloud computing andelectricity: beyond the utility model, Commun. ACM 53 (2010) 32–34.

[25] D. Wang, Y. Song, Y. Zhu, Information platform of smart grid basedon cloud computing, Dianli Xitong Zidonghua(Automation of ElectricPower Systems) 34 (2010) 7–12.

[26] M. Armbrust, A. Fox, R. Griffith, A.D. Joseph, R. Katz, A. Konwinski, G.Lee, D. Patterson, A. Rabkin, I. Stoica, et al., A view of cloudcomputing, Commun. ACM 53 (2010) 50–58.

[27] K. Birman, D. Freedman, Q. Huang, P. Dowell, Overcoming cap withconsistent soft-state replication, Computer 45 (2012) 50–58.

[28] Q. Zhang, L. Cheng, R. Boutaba, Cloud computing state of the art andresearch challenges, J. Internet Serv. Appl. 1 (2010) 7–18.

[29] P. Mell, T. Grance, The nist definition of cloud computing draft, NISTSpec. Pub. 800 (2011) 145.

[30] R.M. Ward, R. Schmieder, G. Highnam, D. Mittelman, Big datachallenges and opportunities in high-throughput sequencing, SystBiomed. 1 (2013) 0–1.

[31] A. Iosup, S. Ostermann, M. Yigitbasi, R. Prodan, T. Fahringer, D.Epema, Performance analysis of cloud computing services for manytasks scientific computing, IEEE Trans. Parallel Distrib. Syst. 22(2011) 931–945.

[32] M. Jensen, J. Schwenk, N. Gruschka, L. Iacono, On technical securityissues in cloud computing, in: IEEE International Conference onCloud Computing, CLOUD’09, IEEE, 2009, pp. 109–116.

[33] W. Deng, F. Liu, H. Jin, B. Li, D. Li, Harnessing renewable energy incloud datacenters: opportunities and challenges, IEEE Network Mag.(2013).

[34] N. Hasan, M.R. Ahmed, Cloud computing: opportunities andchallenges, J. Modern Sci. Technol. 1 (2013).

[35] H.R. Motahari-Nezhad, B. Stephenson, S. Singhal, Outsourcingbusiness to cloud computing services: opportunities andchallenges, IEEE Internet Comput. Palo Alto 10 (2009).

[36] D.S. Markovic, D. Zivkovic, I. Branovic, R. Popovic, D. Cvetkovic,Smart power grid and cloud computing, Renew. Sust. Energy Rev. 24(2013) 566–577.

[37] A. Ojala, V. Puhakka, Opportunity discovery and creation in cloudcomputing, in: 46th Hawaii International Conference on SystemSciences (HICSS), IEEE, 2013, pp. 4296–4305.

[38] F. Luo, Z. Dong, Y. Chen, Y. Xu, K. Meng, K. Wong, Hybrid cloudcomputing platform: the next generation it backbone for smart grid,in: IEEE Power and Energy Society General Meeting, IEEE, 2012, pp.1–7.

[39] R. Buyya, C. Yeo, S. Venugopal, J. Broberg, I. Brandic, Cloudcomputing and emerging it platforms: vision, hype, and reality fordelivering computing as the 5th utility, Future Gener. Comput. Syst.25 (2009) 599–616.

[40] D. Nurmi, R. Wolski, C. Grzegorczyk, G. Obertelli, S. Soman, L.Youseff, D. Zagorodnov, The eucalyptus open-source cloud-computing system, in: 9th IEEE/ACM International Symposium onCluster Computing and the Grid, CCGRID’09, IEEE, 2009, pp. 124–131.

[41] L. Zheng, Y. Hu, C. Yang, Design and research on private cloudcomputing architecture to support smart grid, InternationalConference on Intelligent Human–Machine Systems andCybernetics (IHMSC), vol. 2, IEEE, 2011, pp. 159–161.

[42] C. Wang, K. Ren, J. Wang, Secure and practical outsourcing of linearprogramming in cloud computing, in: Proceedings IEEE INFOCOM,IEEE, 2011, pp. 820–828.

[43] R. Basmadjian, H. De Meer, R. Lent, G. Giuliani, Cloud computing andits interest in saving energy: the use case of a private cloud, J. CloudComput.: Adv. Syst. Appl. 1 (2012) 5.

[44] I. Egwutuoha, S. Chen, D. Levy, B. Selic, A fault tolerance frameworkfor high performance computing in cloud, in: 12th IEEE/ACMInternational Symposium on Cluster, Cloud and Grid Computing(CCGrid), IEEE, 2012, pp. 709–710.

[45] Data Access and Privacy Issues Related to Smart Grid Technologies,2010. <http://energy.gov/gc/downloads/department-energy-data-access-and-privacy-issues-related-smart-grid-technologies>.

[46] NISTR 7628 Guidelines for Smart Grid Cyber Security, Privacy andthe Smart Grid, vol. 2, 2010. <http://csrc.nist.gov/publications/nistir/ir7628/nistir-7628_vol2.pdf>.

[47] NISTR 7628 Guidelines for Smart Grid Cyber Security, SupportiveAnalyses and References, vol. 3, 2010. <http://csrc.nist.gov/publications/nistir/ir7628/nistir-7628_vol3.pdf>.

[48] A.R. Metke, R.L. Ekl, Security technology for smart grid networks,IEEE Trans. Smart Grid 1 (2010) 99–107.

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/

Page 18: Cloud Computing for Smart Grid applications

13951396139713981399140014011402140314041405140614071408140914101411141214131414141514161417141814191420142114221423142414251426142714281429143014311432143314341435143614371438143914401441144214431444144514461447144814491450145114521453145414551456

1457

14591459

146014611462146314641465146614671468146914701471147214731474

14761476

1477147814791480148114821483148414851486148714881489149014911492149314941495149614971498149915001501

15031503

1504150515061507150815091510151115121513151415151516151715181519

18 M. YigitQ1 et al. / Computer Networks xxx (2014) xxx–xxx

COMPNW 5325 No. of Pages 18, Model 3G

26 June 2014

Q1

[49] D. Wei, Y. Lu, M. Jafari, P. Skare, K. Rohde, An integrated securitysystem of protecting smart grid against cyber attacks, in: InnovativeSmart Grid Technologies (ISGT), IEEE, 2010, pp. 1–7.

[50] A. Rial, G. Danezis, Privacy-preserving smart metering, in:Proceedings of the 10th annual ACM workshop on Privacy in theelectronic society, ACM, pp. 49–60.

[51] F.D. Garcia, B. Jacobs, Privacy-friendly energy-metering viahomomorphic encryption, in: Security and Trust Management,Springer, 2011, pp. 226–238.

[52] K. Kursawe, G. Danezis, M. Kohlweiss, Privacy-friendly aggregationfor the smart-grid, in: Privacy Enhancing Technologies, Springer, pp.175–191.

[53] C. Efthymiou, G. Kalogridis, Smart grid privacy via anonymization ofsmart metering data, in: First IEEE International Conference on SmartGrid Communications (SmartGridComm), IEEE, 2010, pp. 238–243.

[54] H. Lam, G. Fung, W. Lee, A novel method to construct taxonomyelectrical appliances based on load signaturesof, IEEE Trans. Consum.Electr. 53 (2007) 653–660.

[55] J. Byun, Y. Kim, Z. Hwang, S. Park, An intelligent cloud-based energymanagement system using machine to machine communications infuture energy environments, in: IEEE International Conference onConsumer Electronics (ICCE), IEEE, 2012, pp. 664–665.

[56] X. Jin, Z. He, Z. Liu, Multi-agent-based cloud architecture of smartgrid, Energy Procedia 12 (2011) 60–66.

[57] P. Wang, L. Rao, X. Liu, Y. Qi, D-pro: dynamic data center operationswith demand-responsive electricity prices in smart grid, IEEE Trans.Smart Grid 3 (2012) 1743–1754.

[58] K. Nagothu, B. Kelley, M. Jamshidi, A. Rajaee, Persistent net-ami formicrogrid infrastructure using cognitive radio on cloud data centers,IEEE Syst. J. 6 (2012) 4–15.

[59] N. Sadashiv, S. Kumar, Cluster, grid and cloud computing: a detailedcomparison, in: 6th International Conference on Computer Science &Education (ICCSE), IEEE, 2011, pp. 477–482.

[60] A. Di Meglio, M. Riedel, S. Memon, C. Loomis, D. Salomoni, Grids andclouds integration and interoperability: an overview, in: Proceedingsof the International Symposium on Grids and Clouds and the OpenGrid Forum (ISGC 2011 & OGF 31), vol. 1, Academia Sinica, Taipei,Taiwan, March 19–25, 2011, p. 112. <http://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=133,id.112>.

[61] G. Towns, J. Ferguson, D. Fredrick, G. Myers, Grid User Support BestPractices, 2009.

[62] D. Milojicic, I. Llorente, R. Montero, Opennebula: a cloudmanagement tool, IEEE Internet Comput. 15 (2011) 11–14.

[63] P. Verissimo, A. Bessani, M. Pasin, The tclouds architecture: open andresilient cloud-of-clouds computing, in: IEEE/IFIP 42nd InternationalConference on Dependable Systems and Networks Workshops (DSN-W), IEEE, 2012, pp. 1–6.

[64] T. Singh, P. Vara, Smart metering the clouds, in: 18th IEEEInternational Workshops on Enabling Technologies: Infrastructuresfor Collaborative Enterprises, WETICE’09, IEEE, 2009, pp. 66–71.

[65] K. Shvachko, H. Kuang, S. Radia, R. Chansler, The hadoop distributedfile system, in: IEEE 26th Symposium on Mass Storage Systems andTechnologies (MSST), IEEE, 2010, pp. 1–10.

[66] S. Zhang, J. Wang, B. Wang, Research on data integration of smartgrid based on iec61970 and cloud computing, Adv. Electron. Eng.Commun. Manage. 1 (2012) 577–582.

[67] L. Rao, X. Liu, L. Xie, Z. Pang, Hedging against uncertainty: a tale ofinternet data center operations under smart grid environment, IEEETrans. Smart Grid 2 (2011) 555–563.

[68] S.-Y. Chang, C.-F. Lai, Y.-M. Huang, Dynamic adjustable multimediastreaming service architecture over cloud computing, Comput.Commun. 35 (2012) 1798–1808.

Please cite this article in press as: M. Yigit et al., Cloud Computing for10.1016/j.comnet.2014.06.007

Melike Yigit received her B.S. and M.S.degrees in computer engineering from Bah-cesehir University, Istanbul, Turkey, in 2010and 2012, respectively. Currently, she is aPh.D. student in Bahcesehir University, Istan-bul, Turkey and works at Turkish Airlines(THY), which is a national airlines in Turkey,as a Business Analyst. Before starting THY, sheworked in Huawei Technologies Co. Ltd. andAlcatel-Lucent Teletas as a software developerand San-Tez Project student, respectively. Hercurrent research interests are smart grid

communications, power line communications and wireless adhoc andsensor networks.

Vehbi Cagri Gungor received his B.S. and M.S.degrees in Electrical and Electronics Engi-neering from Middle East Technical University,Ankara, Turkey, in 2001 and 2003, respectively.He received his Ph.D. degree in electrical andcomputer engineering from the Broadband andWireless Networking Laboratory, GeorgiaInstitute of Technology, Atlanta, GA, USA, in2007 under the supervision of Prof. Ian F.Akyildiz. Currently, he is an Associate Professorand Chair of Computer EngineeringDepartment, Abdullah Gul University (AGU),

Kayseri, Turkey. His current research interests are in smart gridcommunications, machine-to-machine communications, next-generationwireless networks, wireless ad hoc and sensor networks, cognitive radio

networks, and IP networks. Dr. Gungor has authored several papers inrefereed journals and international conference proceedings, and has beenserving as an editor, reviewer and program committee member tonumerous journals and conferences in these areas. He is also the recipientof the IEEE Trans. on Industrial Informatics Best Paper Award in 2012, IEEEISCN Best Paper Award in 2006, the European Union FP7 Marie Curie IRGAward in 2009, Turk Telekom Research Grant Awards in 2010 and 2012,and the San-Tez Project Awards supported by Alcatel-Lucent, and theTurkish Ministry of Science, Industry and Technology in 2010.

Selcuk Baktir received the B.Sc. degree inelectrical engineering in 2001, from BilkentUniversity, Ankara, Turkey, and the M.Sc. andPh.D. degrees in electrical and computerengineering in 2003 and 2008, respectively,from Worcester Polytechnic Institute, MA,USA. Currently, he is an Assistant Professor atthe Department of Computer Engineering,Bahcesehir University, Istanbul, Turkey.Before joining Bahcesehir University, he wasworking as a research scientist at TUBITAKBILGEM, Kocaeli, Turkey. His current research

interests include applied cryptography and data security. He is the reci-pient of the IBM Research Pat Goldberg Memorial Best Paper Award in2007 and the European Union FP7 Marie Curie IRG Award in 2010.

Smart Grid applications, Comput. Netw. (2014), http://dx.doi.org/