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Description

The generic PV plant is a positive-sequence dynamic modular, hierarchical dynamic representation of a utility-scale solar plant designed for large-scale transient stability studies. It is implemented with three WECC standard dynamic models: the Renewable Energy Plant Controller – Type A (REPC_A), the Renewable Energy Electrical Controller – Type A (REEC_A), and the Renewable Energy Generator/Converter – Type B (REGC_B). The “generator” model (REGC_B) provides current injections into the network solution, the electrical control model (REEC_A) for local active and reactive power control, and the plant controller model (REPC_A) allows for plant-level active and reactive power control[1].

The generic PV plant provides a reasonably good representation of the dynamic electrical performance of solar photovoltaic power plants at the point of interconnection with the bulk electric system, and not necessarily within the solar PV power plant itself. It is suitable for studying the system response to electrical disturbances, not solar irradiance transients (i.e., available solar power is assumed constant through the duration of the simulation). Electrical disturbances of interest are primarily balanced transmission grid faults (external to the solar PV power plant), typically 3 - 9 cycles in duration, and other major disturbances such as loss of generation or large blocks of load. Users can represent differences among specific inverter and/or plant controller responses by selecting appropriate model parameters and feature flags [2].

The generic PV plant modeling structure is shown below:

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Current Injection (REGC_B model)

The generic PV plant is modeled as a controlled current source connected to the grid.

The REGC_B block represents the converter–grid interface and injects the commanded active and reactive current components into the network. It assumes a fast inner current control loop and directly enforces the commanded current at the terminal.

Thus, REGC_B defines the physical plant–grid interaction by injecting controlled current into the network interface.

Local Active Power and Reactive Power Control (REEC_A model)

The REEC_A block converts active and reactive power references into current commands.

Depending on the selected control mode, the Q-control loop can regulate terminal voltage or reactive power by generating the reactive current command Iqcmd​.

The P-control loop generates the active current command Ipcmd to track the active power reference Pref​, including ramp-rate limits if enabled.

The converter current is limited by its maximum current capability. The active and reactive current components must satisfy

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Since the generic PV model represents a generator, only positive active current is allowed (I_p,min⁡=0).

If the requested active and reactive currents exceed the converter capability, a priority logic (determined by the Pqflag) adjusts the commands so that the total current remains within the limit. Depending on the selected setting, either active or reactive current is given priority.

Plant Level Active and Reactive Power Control ( REPC_A model)

The REPC_A block performs supervisory plant-level control.

It regulates plant voltage (V), reactive power (Q), active power (P), and optionally provides frequency-droop-based active power response, depending on selected feature flags.

REPC_A receives measured branch quantities (Qbranch, Pbranch), regulated bus voltage (Vreg), system frequency (Freq, FreqRef), and external references (Qref, PlantRef, Vref).

Through its plant-level V/Q control and plant-level P control loops, it generates the reactive power command Qext ​ and active power command Pref, which are sent to the inverter-level controller (REEC_A).

Network Interface

The network solution solves the system algebraic equations to determine bus voltages, currents, and power flows.

The injected current from REGC_B interacts with the grid through this solution. The resulting terminal voltage and electrical measurements are fed back to REPC_A, REEC_A, and REGC_B, closing the control loop.

Active and Reactive Control Options

The models need the proper flag and/or input parameter settings for various active and reactive power control functionality.

Active power control options

Reactive power control options

Mask and Parameters

The generic PV mask contains four tabs, including three blocks: REPC_A, REEC_A, and REGC_B, and an initialization tab: Initial Values

For the three-block parameter configuration, details could be found in each block documentation.

REPC_A

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REEC_A

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REGC_B

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Load Flow

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Name	Unit	Description

Name	Unit	Description
BusType		Terminal bus type. Dropdown list: Swing (Fixed V (PQ balance)), PV (Fixed P and V), and PQ (Fixed P and Q)
Voltage	V	Load flow constraint
Angle	degree	Load flow constraint
Qmin	Mvar	Minimum reactive power allowed in the load flow solution (var)
Qmax	Mvar	Maximum reactive power allowed in the load flow solution (var)
P	MW	Active power
Q	Mvar	Reactive power

Inputs, Outputs and Signal Available for Monitoring

Inputs

Outputs

Acknowledgements

The development of the Generic PV Plant block in the Smart Inverter Control Library is a contribution of CanmetENERGY at Natural Resource Canada.

Reference

[1]   Model User Guide for Generic Renewable Energy System Models, EPRI, October 2023.

[2] WECC-Solar-PV-Dynamic-Model-Specification, WECC REMTF, September 2012.