Western Electricity Coordinating Council
Power Plant Model Validation Data Task Force
Roadmap for Wind and Solar Power Plant
Model Data and Validation
June 2015
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Background
Regulatory Landscape
Accurate and validated models are required for reliable and economic power system operations.
NERC Reliability Standards are developed to ensure the availability of accurate power system
models for power system planning and operational studies, including:
NERC MOD-032 requires Generator Owners to provide powerflow and dynamic models for their
power plants and generating equipment
NERC MOD-025 requires Generator Owners to perform verification of generator active and reactive
power capabilities
NERC MOD-026 and -027 require Generator Owners to perform verification of generator excitation
control and governor control models respectively
Model Development Efforts
WECC Renewable Energy Modeling Task Force (REMTF) led a multi-year effort in developing
models for wind and solar generators.
Powerflow models
Wind power plant powerflow modeling guidelines were developed in 2008. A methodology for
calculating collector system equivalent was developed, and typical data sets were provided for
underground and overhead collector systems. REMTF guidelines have been adopted by most wind
power plants operators in WECC. Furthermore, BPA made their EMS and state estimator models
consistent with planning models. Powerflow models of wind power plants are proven to work and
fairly mature.
Dynamic models
Development of wind generation dynamic models was done in phases. Initial implementation of type
3 and 4 wind generation models (wt3x, wt4x) represented a limited set of wind generation
manufacturers. Recently developed second phase is more modular and has capabilities to capture a
wider group of wind generation turbine makes and models. However, the second phase of wind
generation dynamic models is not well understood outside WECC REMTF, very few planners
understand the model, or its parameter sensitivity. Therefore, it would be inappropriate at this time to
require Generator Owners to provide verified dynamic model data for compliance with NERC MOD
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Reliability Standards. A more collaborative industry-expert approach would be more constructive to
ensure accurate wind power plant models are available for system planning and operating studies.
Dynamic Performance Monitoring
Western Interconnection had greatly expanded monitoring of power plant dynamic performance
through investments made under Western Interconnection Synchrophasor Program (WISP). A
number of PMUs were placed at wind power plants for the purpose of dynamic response monitoring
and model validation. Over the last several years, a good library of disturbance events was recorded
for various types of wind power plants. These recordings can be used for validation of the second
phase of wind generation models.
Voltage Controls
Many transmission paths in Western Interconnection are voltage stability limited. Therefore, correct
representation of voltage controls in powerflow, voltage stability, and transient stability studies is
essential. There is a wide variety of voltage and power factor control options in wind and solar
power plants:
- Type 1 and 2 wind generators are not capable of continuous voltage control. Early plants
with type 1 or 2 generators used plant-level switched shunt capacitors. Reactive power
control with voltage supervision is often practiced at these plants. More recent type 2 plants
include STATCOM for continuous voltage control, often coordinated with shunt capacitor
switching. Voltage control point and coordination between STATCOM and shunts must be
modeled.
- Type 3 and 4 generators are capable of voltage controls. These plants often include shunt
capacitors for compensating reactive power losses. Voltage control point and coordination
between generator reactive and shunts must be modeled. Some of the earlier plants with type
3 and 4 generators operate in power factor mode with voltage over-ride.
Changes in voltage control mode have been observed. Therefore, continual monitoring of wind
power plant voltage control mode is required for operational mode. Wind power ramps and voltage
disturbances can be used for verifying voltage control models.
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Approach
Task 1: Compile List of Wind and Solar Power Plants in WECC
WECC Power Plant Model Validation Data Task Force (PPMVDTF) will use the latest WECC
operating base cases to develop a list of wind and solar plant models. According to WECC Data
Preparation Manual, the power flow data must have plant type specified as a part of generator
record. Generator rated voltage can be also used to identify potential plants.
The list will also include:
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Whether the plant is represented in accordance with WECC Wind Power Plant Modeling
Guidelines
Voltage control point of the power plant
Dynamic models used to represent the power plant
Transmission Planners will be asked to verify the list.
Duration: 3 months.
Task 2: Powerflow Models
According to WECC Data Preparation Manual, all wind and solar power plants must be modeled in
accordance with WECC Wind and Solar Power Plant Modeling Guidelines. These modeling
guidelines are proven to work and fairly mature. These models have been used successfully in
WECC planning base cases as well as EMS state estimator cases.
WECC PPMVDTF will notify Generator Owners whose power plants do not meet powerflow
modeling guidelines.
WECC PPMVDTF will conduct up to three webinars explaining WECC Wind and Solar Powerflow
Modeling Guidelines.
The Generator Owners will be required to bring their wind and solar power plant modeling in
compliance with WECC Data Preparation Manual within 12 months, or provide a technical
justification for continuing previous modeling practice. WECC PPMVDTF will review
justifications.
Duration: 12 months.
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Task 3: Voltage Control
WECC PPMVDTF will survey wind and solar power plant and STATCOM manufactures on typical
voltage control practices they use.
WECC PPMVDTF will develop a methodology and tools for validating wind and solar power plant
models and voltage control mode of operation using data from power ramps and voltage
disturbances.
WECC PPMVDTF will conduct training sessions and webinars to make such tools available to
Transmission Planners and Generator Owners in the Western Interconnection.
WECC PPMVDTF will assist Transmission Planners and Generators Owners in validating the
voltage control mode.
Duration: 24 months.
Task 4: Dynamic Models
Task 4-1. Understanding wind and solar power plant dynamic models
WECC PPMVDTF will work with WECC REMTF on conducting a sequence of webinars on the
second phase of wind and solar power plant models.
WECC PPMVDTF will run dynamic studies to determine the impact of control modes and control
settings on the wind and solar power plant response to grid disturbances.
Duration: 12 months.
Task 4-2. Developing “typical” dynamic data sets
WECC PPMVDTF will conduct studies using PMU data to develop “typical” data sets.
WECC PPMVDTF will conduct a training session with Transmission Planners and Generator
Owners on using “typical” data sets.
Duration: 12 months.
Task 4-3. Updating to plant specific data sets
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WECC PPMVDTF will extend PPMV to wind and solar power plants.
Duration: 12 months.
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