Communications for Smart GridsHem Thukral

Research OfficerISGF

Introduction• Smart grid is a superposition of 2 networks – The electrical network

• Generation• Transmission• Distribution

– The communications network • Core/backbone• Backhaul/Wide Area Network (WAN)• Last mile/access/Neighbourhood Area Network (NAN)/ Field Area Network(FAN)• Home Area Network (HAN)

• Communication is the backbone of a smart grid – 2-way communication is essential for the operation of a smart grid– Monitoring and controlling the power flow in the grid

Topologies in Communications• The topologies that are commonly used are

– Star– Mesh– Ring– Bus– Serial/line

• Selection of a topology depends on the application– Wi-Fi: Star topology– Connecting smart meters to a data concentrator unit: mesh topology– Backbone networks using optical fiber: ring topology– Ethernet: Bus topology– Between an electronic meter and modem: serial topology

Use of Communications in a Smart Grid– AMR– AMI– SCADA/DMS– SCADA/EMS– Wide Area Monitoring System (WAMS) – Substation Automation– Electric Vehicles – Distributed generation– Energy storage– Microgrids– Demand response– Redundant links for critical applications such as Distribution Automation and

Substation Automation

Automated Meter Reading (AMR)

Typical architecture of AMR

AMR is used extensively in R-APDRP for HT consumers, distribution transformers and feeders. Both GSM and CDMA were used. It is reported that reliability is in the range of 50-60%.

(Note: Communications is only ONE-WAY)

Advanced Metering Infrastructure (AMI)

Typical Architecture of AMICOMMUNICATION IS 2-WAY

Advantages of communications in AMI• Consumers could

– View their energy consumption accurately on a regular basis – informed consumer– Manage loads via remote turn ON/OFF and managing total demand – SMART PHONE/IHD to turn

off!– Save money from ToU tariffs by shifting non-priority loads– Face reduced outages (SMART METER WILL CONVEY TO UTILITY)

• Utilities could achieve financial gains by – Reading the meter remotely: REDUCED TRUCK ROLLS– Managing the load curve by introducing demand response, ToU/ToD tariff, etc.

• No need to purchase expensive power at the last hour.– Enabling faster restoration of electricity service after fault/events

• Outage detection easier using Smart Meter– Detecting energy theft/pilferage on near real-time basis– Billing and collection will be automatic

Supervisory Control And Data Acquisition (SCADA) for DMS and EMS

Communications for SCADA(contd.)• Monitoring – Status• Switch status, protection relay status, fault of FTU, flow detection,

momentary voltage drop etc.–Measurement• Voltage, current, active power, reactive power, power factor etc.

• Control– Switch gear (open/close)– Relay (in use/not in use)

Typical Architecture of SCADA

Wide Area Monitoring System(WAMS)

Typical architecture of WAMS

21 Sep 2012 WG <no> : <WG Title>

Communications for WAMS

–Voltage stability assessment–Oscillation detection–Post-fault analysis–State estimation–System state prediction

Other applications• Substation Automation• Distributed Generation• Electric Vehicles• Energy Storage• Microgrids• Demand Response• Home Automation/Building Automation

Characteristics of communications for smart grids• High bandwidth

• AMI/AMR - low• SCADA - high

• Low latency• AMI/AMR – low• SCADA - high

• High availability of network• High reliability• High level of security

• Meter – privacy of data• SCADA – trip feeders using ONE click of

mouse• High level of scalability• Long range: choice of frequency!• Low power consumption

• Long technology life-cycle• Compliant with regulations

• 865-867 MHz and 2.4 GHz ONLY;

• Interoperable• Low Total Cost of Ownership (TCO)

– Cost of infrastructure acquisition (towers, PLC lines)

– Cost of communications media acquisition (license fee)

– Operating cost

Potential Smart Grid Solutions

Wired options• PLC (Narrowband and

broadband)• Ethernet(co-axial cable,

twisted pair, optical fiber, radio)

• RS-232• RS-485

Wireless options• Low Power RF (eg. 6LOWPAN, ZIGBEE,

proprietary)– Operate mostly in SLEEP mode

• Cellular (GPRS, EDGE, 3G, HSPA, LTE, WiMAX)

• Wi-Fi (data security ???)• V-SAT• Infra-Red• Bluetooth• Private point-to-point microwave links• Private point-to-multipoint microwave

links

Wireless Spectrum – Global Scenario

For India, 2 MHz might be too less• Millions of IEDs in a smart grids• Billions of smart devices in a smart city

Spectrum for PLC – Global scenarioRegion Frequency band for PLCEurope CENELEC A: 3-95 KHz for power utilities

CENELEC B: 95-125 KHz for any application

CENELEC C: 125-140 KHz for in-home networking with mandatory CSMA/CA protocol

CENELEC D: 140-148.5 KHz Alarm and Security systems

USA 10-490 KHz, and

2-30 MHz

Japan 10-450 KHzChina 3-500 KHz

Selection Criteria – some parametersCriteria Preferred Technologies

High Bandwidth Optical fiber, BPL, WiMAX, 3G, HSPA, LTE, VSAT

Low Latency DSL, optical fiber, Wi-Fi

High Reliability Optical fiber, HSPA, LTE, V-SAT, DSL, Wi-Fi, RS-232, RS-485

High Security Optical fiber, BPL, private RF Pt-to-MPt, WiMAX, V-SAT

Low Cost Narrowband PLC, 6LoWPAN, ZigBee, Wi-Fi, Bluetooth, Infrared, GPRS, EDGE, RS-232, RS-485

The selection of a technology will depend on the application• For mission critical applications (such as Distribution Automation and

Substation Automation), security, latency and reliability will be the key. Cost will not be considered as a parameter during selection.

• For non-critical applications (such as AMI), cost will be decisive.

Case Study (International)

Southern California Edison• AMI – HAN: ZigBee• AMI – NAN: Proprietary RF mesh at 902 MHz• AMI – WAN: 3G• SCADA

Wide area connectivity: Optical fiber (mostly) + V-SAT (for remote locations) Local Area connectivity: Proprietary solution using 902 MHz RF mesh network

Case Study (National)

MSEDCL– AMR for R-APDRP: GPRS using modems for 58,000 meters (feeder + DT

+HT consumers)– Meter reading using HHU

• ZigBee with modified SEP for 6.31 lac meters in dense urban areas• InfraRed for 30 lac meters in rural areas

– Distribution Automation and Substation Automation• Between field devices and RTU: RS-232 • Between RTU and control centre: leased line(optical fiber)

The Way Forward

• Un-licensed communication bands in India are:– 865-867 MHz for low-power RFID devices (un-licenced in 2005)– 2.4 GHz band

• Short range• Interference: Wi-Fi, microwave ovens etc.

• Use of lower frequency bands (<865 MHz) could be considered• Additional spectrum might be needed to cater to millions of connected

devices as part of the IoT • National Optical Fiber Network (NOFN)

– Connecting all 33 kV substations USING OPTICAL FIBER for e-governance, e-learning etc.– Smart Grid applications could use this network

The Way Forward (contd.)

• To ensure interoperability, standards-based communication technologies will be promoted – IP-based technologies will gain traction in the market

• Use of proprietary solutions would reduce as these do not lead to interoperability

• Standardization in India - BIS– For formulation of standards in the field of Electronics and IT

• Electronics and IT Department (LITD) – Sectional Committee LITD-10 (Power System Control and Associated

Communications) has Panels dedicated to smart grids• AMI, Interoperability, CIM, Cyber Security, Digital Architecture

Conclusion

• Different geographic regions have different requirements and constraints– PLC might not be feasible in some areas where the wiring infrastructure is

not clean– Low power RF mesh networks might not be feasible in densely populated

areas

• No ‘one’ communication technology will dominate the smart grid– It will be a mix-and-match of different technologies

• Choice of technology will depend on the application

Conclusion (contd.)

• Performance (bandwidth, latency, reliability, security, availability etc.) needs to be balanced with cost

• The Total Cost of Ownership (TCO) to be considered – Cost of infrastructure acquisition– Cost of communications media acquisition– Operating cost

• The results of the 14 pilot projects will give us an indication on what technology to use for large scale roll outs

Thank you..