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Purpose of Advanced Inverters
Mitigation and Grid support
PV Distribution System Modeling Workshop
Presenter: Richard Brav...
Solar PV Inverters Advanced Features
1
SCE started assessing solar PV inverters in 2009
• Tested multiple U.S. standard in...
2
Ramp Rate
• Potential benefits
– Prevent unintended over-voltages on distribution circuits
– Provide time for utility vo...
Voltage Ride Through
• Potential benefits
– Prevent unnecessary disconnection
– Prevent longer voltage recoveries
– Provid...
Dynamic Watts/Hz
• Potential benefits
– Prevent unnecessary disconnection
– Prevent unintended over-voltages during
surplu...
Autonomous Volt/VAR Support
• Potential benefits
– Prevent unintended under/over-voltages
– Support motor VAR demand
– All...
Auxiliary Power Supply
• Potential benefits
– Power to loads during emergency events
– Powers outlet isolated (does not ba...
Distribution
BUS
SUBSTATION FIELD
Thevenin
Equivalent
Isc=17KA
Feeder “A”CB1
ISC= 17.5kA
Feeder “B”
L1a
L2a
CB2
ISC= 17.5k...
Solar PV
Generation3
Rural Circuits Impacts
8
Distribution
BUS
Distribution feeder
Cap1
SW4
Load4
M
CB1
Cap2
Cap3Cap4
DIST...
FIDVR Impacts
9
• Present inverter standards will trip inverters during low voltage ( FIDVR) events
• Events will worsen w...
Solar PV Inverters Advanced Features
10
ADVANCED FEATURE
PRESENTLY
AVAILABLE? BENEFITS
RAMP RATES  Prevent local overvolt...
Conclusions
• Advanced features may need to be modified based on needs
– Residential inverter features infrastructure need...
Richard Bravo
Southern California Edison
richard.bravo@sce.com
12
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2014 PV Distribution System Modeling Workshop: Purpose of Advanced Inverters- mitigation and grid support: Richard Bravo, SCE

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2014 PV Distribution System Modeling Workshop: Purpose of Advanced Inverters- mitigation and grid support: Richard Bravo, SCE

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2014 PV Distribution System Modeling Workshop: Purpose of Advanced Inverters- mitigation and grid support: Richard Bravo, SCE

  1. 1. Purpose of Advanced Inverters Mitigation and Grid support PV Distribution System Modeling Workshop Presenter: Richard Bravo, SCE
  2. 2. Solar PV Inverters Advanced Features 1 SCE started assessing solar PV inverters in 2009 • Tested multiple U.S. standard inverters (res. and comm.) • Tested several “Smart Inverters” • Provide feedback to national and state standards
  3. 3. 2 Ramp Rate • Potential benefits – Prevent unintended over-voltages on distribution circuits – Provide time for utility voltage support devices to adjust states properly – LOCAL VOLTAGE SUPPORT
  4. 4. Voltage Ride Through • Potential benefits – Prevent unnecessary disconnection – Prevent longer voltage recoveries – Provides limited short circuit – Prevent/contain voltage events (FIDVR, etc) – SUPPORT GRID STABILITY 3
  5. 5. Dynamic Watts/Hz • Potential benefits – Prevent unnecessary disconnection – Prevent unintended over-voltages during surplus generation – SUPPORT GRID STABILITY 4
  6. 6. Autonomous Volt/VAR Support • Potential benefits – Prevent unintended under/over-voltages – Support motor VAR demand – Allow CVR when needed 5 – Support voltage imbalance when VARs are independent in each phase – SUPPORT LOCAL VOLTAGE
  7. 7. Auxiliary Power Supply • Potential benefits – Power to loads during emergency events – Powers outlet isolated (does not back- feed in to the grid) 6 – CUSTOMER SUPPORT LOCAL VOLTAGE
  8. 8. Distribution BUS SUBSTATION FIELD Thevenin Equivalent Isc=17KA Feeder “A”CB1 ISC= 17.5kA Feeder “B” L1a L2a CB2 ISC= 17.5kA L1b L2b Feeder “C”CB3 ISC= 17.5kA Feeder “D” L3a L4a CB4 ISC= 17.5kA L3b L4b Feeder “E”CB5 ISC= 17.5kA Feeder “F” L5a L6a CB6 ISC= 17.5kA L5b L6b Circuit Breakers Impacts 7 P_1a=7MWG1a Isc=430A 17.0kA 17.43kA P_1a=7MWG1a Isc=430A 17.86kA • Distribution circuits were designed for one way power flow • DG will alter this power flow and provide additional fault current • DG could provoke CB to go above their ratings
  9. 9. Solar PV Generation3 Rural Circuits Impacts 8 Distribution BUS Distribution feeder Cap1 SW4 Load4 M CB1 Cap2 Cap3Cap4 DISTRIBUTION SUBSTATION Cap5 FIELD P Q InfiniteBus SW3 SW1 SW2 Load5 M Load2 M Load1 M Load6 M Load3 M Solar PV Generation1 Solar PV Generation2 SWY SWX • Utilities are facing challenges during DG interconnections specially at rural areas • DG can provoke OV due to cable limitations VR
  10. 10. FIDVR Impacts 9 • Present inverter standards will trip inverters during low voltage ( FIDVR) events • Events will worsen with higher DG penetration with current standards • A good VRT settings can support the grid during these type of events
  11. 11. Solar PV Inverters Advanced Features 10 ADVANCED FEATURE PRESENTLY AVAILABLE? BENEFITS RAMP RATES  Prevent local overvoltages during low-load/high-gen VRT  Support transmission system FRT  Support transmission system WATTS-HZ DYNAMIC SUPPORT  Supports grid during over generation conditions VOLTAGE (VAR) SUPPORT (PHASE INDEPENDENT)  Supports local voltage Support voltage imbalance due to 1Φ load/generation VOLTAGE SUPPORT AT NIGHT TIME  Supports grid specially during high load conditions 10% ABOVE RATING FOR GRID  Owner not lose revenue during grid support STANDARD COMMUNICATIONS Owners/utility AUXILIARY POWER SUPPLY  Provide owners emergency power Some day solar PV inverter may help: – Damping voltage oscillations – Reduce/eliminate Flickering – Voltage support during emergencies – Reduce/eliminate harmonics – Support some micro-grids
  12. 12. Conclusions • Advanced features may need to be modified based on needs – Residential inverter features infrastructure needed to communicate – Commercial grid-tied inverter features may be practical for utilities to adjust • Develop testing standards – To comply with UL certification • Utilities will face additional work when advanced features are adopted: – Develop and validate advanced inverter models – Study the effects on present voltage support devices – Pilot advanced inverters – Design and build communications infrastructure – Revise interconnection standards/procedures 11
  13. 13. Richard Bravo Southern California Edison richard.bravo@sce.com 12 12

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