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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/8/13/2019 Renewable Penetration Issues
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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.