renewable penetration issues

8/13/2019 Renewable Penetration Issues

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Issues With Renewable Penetration

And Mitigation Methodologies

Presented by:

Vaibhav Gholase(133070041)

Nimish Kothari(123076002)


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Shortfall of renewable energy sources

Effects of high penetration of intermittent resources

Potential PV penetration problems and solution

Islanding related issues

Problems related to Passive Techniques

Possible Islanding solutions

Future scope

Introduction


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Background and Motivation

Heavy increment in renewables in recent years

Higher capacity plants are being set up

Existing grids not designed for high penetration and facing problems

Increase in decentralized generations increases protection issues

Normal Islanding methods non-economical and non-reliable

Few active methods degrade power quality

Motivation: Islanding techniques having high reliability, no power

degradation, economical and easy to implement


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Shortfall of Renewable Energy Sources[1]

Capacity factors in the range of 1020 %

No dispatch capability without storage.

Ultra-fast ramping regulations required

No reactive power and voltage support capability.

No Low-Voltage-Ride-Through (LVRT) capability

Power quality may not comply IEEE-519 and other standards.

[1]Johan H.R. Enslin, Network Impacts of High Penetration of Photovoltaic Solar Power Systems, IEEE

PES General Meeting. Pp. 15, 2010.


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Effects of High Penetration of Intermittent Resources [1]

Reverse Power flow

Poor Power Quality

Increased Short circuit Current

Transient Stability Issue

Electromagnetic Transients

Protection & Islanding

Power leveling and energy balancing


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*2+Quanta Technology White Paper: Grid Impacts and Solutions of Renewables at High Penetration

Levels, June 2009, www.quantatechnology.com.

Potential PV Penetration Problems: [2]

Require fast ramping regulation services

Ramping regulation too slow and is polluting much more

Normally regulation requirement 1% of peak load dispatch

2% for 20% penetration

4% for 33% penetration

Regulation services counteract the emissions savings


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According to IEEE Standard 1547:

Distributed Resources (DR) shall not actively regulate voltage at PCC

Most DE operate at unity power factor.

Result in low power factor at the PCC

It is beneficial to regulate VARs at a local level

Potential PV Penetration Problems:[3]

[3] M. Y. Vaziri et al., Volt/VAr regulation and issues with high penetration of renewables on

distribution systems,. 2012 IEEE 13th International Conference on IRI, Pp. 519 - 524


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Potential PV Penetration Problems:[4]

Reactive power limitations on failure of conventional generators

Entire DG capacity can not be used

[4]D. Gaikwad and S. Mehraeen, "Reactive power considerations in reliability analysis of photovoltaicsystems," IEEE Green Technologies Conference, pp.1-6, 19-20 April 2012.


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Potential PV Penetration Problems:

Consider a simplified equivalent circuit of distribution line with PV as DG

connected system :

Eg Vt IPVZl

ZgL

)lt g g PV

l g

ZV (E + Z . I

Z Z

voltage profile over the line is governed by the generator terminal voltage and PV

penetration level


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0.9

0.98

0.96

0.94

0.92

1

1.08

1.06

1.04

1.02

1.1

0 1 2A-

2B

3 4 5 6

Primary Feeder Voltage

Service Entrance Voltage

Primary Feeder Voltage limits

Service Entrance Voltage limits

Switch

Capacitor

Step Voltage

RegulatorOLTC

Vo

ltage(p.u.)

Feeder

OLTC

Step Voltage

Regulator

Without PV and full load

With high PV and light load

Voltage profiles show contradictory nature, the line voltage increases as

move away from the point of supply feeder


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Voltage(pu)

withDG

Voltage(pu)witho

utDG

Fig: Courtesy[5]

Voltage Profile at feeders B11 to B17. B11 being the closest to substation and B17 the farthest


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Possible solution : Proper placement of PV sources

Proper placement of DG reduce active and reactive power demand

Dependent on system PF

Expected Energy Not Supplied (EENS) with different placements of PV in IEEE

14bus system (without PV EENS_P was 21939MWH/yr)

Fig.(a) at PF=0.9 Courtesy[4] Fig.(b) at PF=0.85 Courtesy[4]


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voltage support

improved low voltage ride through (LVRT)

Fast regulation

Battery Energy Storage System(BESS) make PV power cost effective.

avoided cost in the delay of upgrading the transmission line

reduction of peaker generator plant maintenance costs

Pollution free solution

Minimization of Curtailments of a remote PV solar

Possible solution: STATCOM-BESS[1]


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Inherent capability of inverters to supply reactive power

can provide 46% KVAr even while supplying rated KW

voltage profile tightly coupled with reactive power

Possible solution: Voltage control by PV Inverters


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Islanding Related Issues..


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Introduction

Islanding:- A portion of an area EPS that is still energized after grid failure

Unintentional Islanding :- DR interconnecting the PCC cease to energize the

area EPS(IEEE Std 1547-2003 4.4.1)

Intentional Islanding:- DR can energize local load with rest of grid isolated by

disconnect switch(IEEE 1547.4)

Necessity of Islanding detection

Standards:

Quality factor(Q) = 1 (IEEE 1547), Q = 2.5(IEEE 929-2000)

OUF= f+1.5 & f-1.5

OUV= 110% & 88% of nominal voltage

Testing condition :- f = (resonance frequency of RLC) [2]f0

6.Ku Nurul Edhura Ku Ahmadn, JeyrajSelvaraj, Nasrudin AbdRah ,A review of the islanding detection methods in grid-

connected PV inverters ,Renewable and Sustainable Energy Reviews 21 (2013)

7.IEEE Standard 929-2000: IEEE Recommended practice for utility interface of photovoltaic (PV) systems.


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NDZ of passive methods

* NDZ should be reduced for effective detection of Islanding

8.Fei Wang, Zengqiang Mi,Passive Islanding Detection Method for Grid Connected PV System, International Conference

on Industrial and Information Systems,2009.

[3]


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Islanding Detection Techniques


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Grid Resident Methods

Fig 1: SPD Fig 2: PLCC based technique

Fig 3: External capacitor Switching


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Inverter Resident Methods

PLL based Islanding detection [4]

9.Fei Wang,M. Ciobotaru, V. Agelidis and R. Teodorescu,Accurate and Less-Disturbing Active Anti-islanding Method based

on PLL for Grid-Connected PV Inverters,Power Electronics Specialists Conference, 2008. PESC 2008.


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GEFS [10]

10. Grid Converters For Photovoltaic And Wind Power Systems by Remus Teodorescu,Marco Liserre and Pedro Rodrguez.


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Thank you


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References

[1]Johan H.R. Enslin, Network Impacts of High Penetration of Photovoltaic

Solar Power Systems, IEEE PES General Meeting. Pp. 15, 2010.

*2+Quanta Technology White Paper: Grid Impacts and Solutions of Renewables

at High Penetration Levels, June 2009, www.quantatechnology.com.

[3] M. Y. Vaziri et al., Volt/VAr regulation and issues with high penetration of

renewables on distribution systems,. 2012 IEEE 13th International Conference

on IRI, Pp. 519 - 524

[4]D. Gaikwad and S. Mehraeen, "Reactive power considerations in reliability

analysis of photovoltaic systems," IEEE Green Technologies Conference, pp.1-6, 19-20 April 2012.

[5]S. Ali, N. Pearsall, et al., Impact of High Penetration Level of Grid-Connected

Photovoltaic Systems on the UK Low Voltage Distribution Network,

International Conference on Renewable Energies and Power Quality, Santiago

de Compostela, 28-30 March 2012, pp. 1-4.
http://www.quantatechnology.com/http://www.quantatechnology.com/


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6.Ku Nurul Edhura Ku Ahmadn, JeyrajSelvaraj, Nasrudin AbdRah ,A review of the

islanding detection methods in grid-connected PV inverters ,Renewable andSustainable Energy Reviews 21 (2013)

7.IEEE Standard 929-2000: IEEE Recommended practice for utility interface of

photovoltaic (PV) systems.

8.Fei Wang, Zengqiang Mi,Passive Islanding Detection Method for Grid ConnectedPV System, International Conference on Industrial and Information Systems,2009.

9.Fei Wang,M. Ciobotaru, V. Agelidis and R. Teodorescu,Accurate and Less-

Disturbing Active Anti-islanding Method based on PLL for Grid-Connected PV

Inverters,Power Electronics Specialists Conference, 2008. PESC 2008.

10. Grid Converters For Photovoltaic And Wind Power Systems by Remus Teodorescu,

Marco Liserre and Pedro Rodriguez.

renewable penetration issues

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