california iso experience with der model as a part of ... planning...iso public page 5 der modeling...
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Irina Green, Senior Advisor, Regional Transmission,California ISO
NERC SPIDER WGJuly 2019
California ISO Experience with DER Model as a Part of Composite Load
Model
ISO Public Page 2
NERC SPIDER (System Planning Impact from DER) WG – DER_A Modeling Guideline
New DER_A dynamic model now available and is released in all major positive sequence simulation software platforms. Industry seeking guidance on how to use
and parameterize the model NERC SPIDERWG developed guideline
for how to use the DER_A model, and how to develop parameter values for the model
The Guideline is posted for comments on the NERC website
ISO Public Page 3
NERC SPIDER DER_A Modeling Guideline overview
Provides detailed understanding of the model and how to use it as stand alone or a part of composite load model
Provides recommendations for developing parameters values for the model
Provides guidance for modeling utility-scale DER (U-DER) and retail-scale DER (R-DER)
Provides values of DER_A parameters to use Was developed based on the existing NERC DER modeling
guidelines developed by NERC LMTF and published in December 2016 and September 2017
ISO Public Page 4
DER Modeling Framework, Utility-scale and Retail-Scale DER
Background and Overview of DER_A Model Annotated DER_A Block Diagram, description of blocks in
model Parameterization of the DER_A Model Relation to specific interconnection
requirements/standards (e.g., IEEE 1547-2003, IEEE 1547-2018, CA Rule 21)
Practical DER_A Model Implementation Based on mix of different vintages of IEEE 1547
Study examples Appendices: References, DER_A Block Diagram
NERC SPIDER DER_A Modeling Guideline Content
ISO Public Page 5
DER Modeling Framework
Utility-Scale Distributed Energy Resources (U-DER): DER directly or through a dedicated, non-load serving feeder. connected to the distribution bus. Typically three-phase interconnections, and can range in capacity (e.g., 0.5 to 20 MW).
Retail-Scale Distributed Energy Resources (R-DER): DER that offsets customer load, including residential, commercial, and industrial customers. Typically, residential are single-phase while the commercial and industrial units can be single- or three-phase facilities.
Transmission Planners (TPs) and Planning Coordinators (PCs), in conjunction with their Distribution Providers (DPs), should identify thresholds for U-DER and R-DER modeling based on either the individual or aggregate impact of DER on the BPS.
ISO Public Page 6
Modeling DER in Power Flow and Dynamic Stability
U-DER transformer and feeder modeled. DER modeled as generator
R-DER is modeled as part of composite load
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DER_A Model in Dynamic Stability
Simplified version of the second generation generic renewable energy system models (i.e., regc_a, reec_b, repc_a, lhvrt, lhfrt)
More detailed and flexible than PVD1 model used previously Currently, may represent only aggregated solar PV Standalone or part of composite load model These two models are identical Available in all widely-used software platforms
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DER_A Model Features
Constant power factor and constant reactive power control modes. Allows voltage control to be active along with PF/Q control
Active power-frequency control with droop and asymmetric dead-band Voltage control with proportional control and asymmetric dead-band Fraction of resources tripping or entering momentary cessation at low
and high voltage, includes a timer feature Fraction of resources restoring output following a low or high voltage or
frequency condition Active power ramp rate limits during return to service after trip or enter
service following a fault or during frequency response Active-reactive current priority options Capability to represent generating or energy storage resources.
ISO Public Page 9
DER_A Block Diagram – Active Power-Frequency Control
ISO Public Page 10
Reactive Power-Voltage Controls
Pf Flag = 0 constant Q control, = 1 – constant power factor control
If Kqv=0, no voltage control With dynamic voltage control, recommended Kqv=5, Dbd1= -
0.12, Dbd2=0.1
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Active –Reactive Priority Logic
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Fractional Tripping
Portion of DER tripped for low or high voltage, not all at the same time
Vfrac – portion of DER that recover after voltage returns Frequency tripping – single low and high cut-out points, no partial
tripping Tv – time constant for tripping delay Vl0, Vl1, Vh0, Vh1 – cut-out points for voltage If voltage falls outside the thresholds for the
pre-defined amount of time (below tvl0 or tvl1 or above tvh0 or tvh1), then the recovery of resources changes from the black line to the red line to represent partial recovery
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Trip Settings
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Voltage Source Representation
Modern inverters use a voltage source converter (VSC) behind an impedance
The current through the VSC is controlled by the controls of the inverter.
ipcmd and iqcmd are used to evaluate the voltage drop across the impedance Xe
Rrpwr – is active current ramp rate, how fast recovers after faults
Tg=0.02, Xe = 0.25 for all inverters
ISO Public Page 15
CAISO Studies of DER_A Model as Part of Composite Load. Examples of Different DER_A Parameters
CAISO models behind the meter DER as a part of load for the last two years. Software used was GE PSLF Version 21.06
2020 Summer Peak case with high renewable generation: high renewable output, including DER that are part of composite load model
Also high load, thus stalling of single-phase air-conditioners with faults
Changed threshold for modeling with composite load model –all loads modeled
DER_A parameters as recommended by SPIDER Modeling Guideline
ISO Public Page 16
Case Studied – 2020 Summer Peak, High Renewable Generation
WECC Generation 181,279 MW Load 179,212 MW
CAISO Generation 41,463 MW Load 56,587 MW
PG&E (Northern California) Generation 21,670 MW Load 26,520 MW Behind the meter DER 4,650 MW
ISO Public Page 17
Contingency Studied
The most heavily loaded 500 kV line, Tesla – Metcalf in San Francisco Bay Area
3-phase fault on the sending end with normal clearance (4 cycles)
DER Parameters studied:
Newer inverters with voltage control, kqv=5, deadband +0.1/-0.12
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Loss of Composite Load and DER with Contingency
No criteria violations with this contingency
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230 kV Substation in San Francisco, voltage
VOLTAGE Higher voltage with DER
netted because gross load is lower
Higher voltage with voltage control due to voltage regulation from DER
Old, new and Rule 21 inverters – voltage approximately the same
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DER OUTPUT, MW, feeder # 2
NET LOAD, MW, feeder # 2
New inverters and Rule 21 –approximately the same
Old inverters – slower recovery
Voltage control – less load loss with the fault
230 kV Substation in San Francisco, Load and DER
ISO Public Page 21
60 kV Substation in San Jose, Voltage
VOLTAGESome load and DER may trip after 10 seconds for high voltage
ISO Public Page 22
60 kV Substation in San Jose, load and DER
NET LOAD, MW DER OUTPUT, MW
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Voltage Recovery, San Jose area, 3-Phase Fault Tesla-Metcalf 500 kV
DER NETTED WITH LOAD
EARLY VINTAGE DER
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Voltage Recovery, San Jose area, 3-Phase Fault Tesla-Metcalf 500 kV
NEWER VINTAGE DER
NEWER VINTAGE DER WITH VOLTAGE CONTROL
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DER Output>5 MW, 3-Phase Fault Tesla-Metcalf 500 kV
NEWER VINTAGE DER
NEWER VINTAGE DER WITH VOLTAGE CONTROL
EARLY VINTAGE DER
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3-Phase Fault Tesla-Metcalf 500 kV. Momentary Cessation of Inverters. Ramp 1 p.u, Delay 0.5 sec, Voltage 0.9DER Output>5 MW 2699 MW of net
load reduction, 2747 MW of
gross load reduction in Northern California
48 MW in DER output reduction
DER Output, San Jose
ISO Public Page 27
3-Phase Fault Tesla-Metcalf 500 kV. Momentary Cessation of Inverters. Ramp 1 p.u, Delay 0.5 sec, Voltage 0.9
VOLTAGE SAN JOSE
LOAD SAN JOSE
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Conclusions
The DER model as a part of composite load model works and shows adequate simulation results under various system conditions.
Modeling of the behind the meter DER has significant impact on the study results.
Transient voltage recovery substantially depends on the DER settings, especially on the voltages at which DER trip, timing of the tripping and the fraction of the DER that recovers.
Results suggest that most distribution, as well as transmission bus voltages take 7-9 seconds to recover above 0.88 p.u. for the buses close to the fault for a single contingency and less than 160 ms to recover above 0.45 p.u.
