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Model Static Synchronous Compensator Using Voltage Source Converter

Since R2024a
Open Model

This example models a hybrid var compensator that includes a static synchronous compensator (STATCOM) and a thyristor-switched capacitor (TSC).

Model Overview

The hybrid var compensator comprises one STATCOM and one TSC. Initially, two 400 MW loads and a 300 MW load connect to the primary and secondary side of the substation transformer. The grid voltage is 1 per unit. The TSC is in service and the controller regulates the STATCOM to absorb the reactive power so that the sum of the reactive power from the TSC and the reactive power that the STATCOM absorbs is equal to the required reactive power.

At a simulation time of 0.5 s, the connection to the secondary side of a 450 MW load causes the grid voltage to drop below 0.97 per unit. The STATCOM starts to absorb less reactive power. As a result, the reactive power flowing into the AC grid increases and the grid voltage increases to 0.985 per unit.

At a simulation time of 1 s, a 400 MW load and the 450 MW load disconnect from the primary and secondary side, respectively. This load disconnection causes the grid voltage to rise above 1.02 per unit. The TSC switches out and the STATCOM starts to generate reactive power. As a result, the grid voltage decreases back to 1.006 per unit.

Model Different Levels of Details Using Variant Controls

Use the StaticSynchronousCompensatorParameters script to create variant controls for the STATCOM, TSC, and controller. Specifically, the script defines these Simulink.Variant objects:

  • AverageValueVSC and SwitchingVSC - Use these objects with the average-value and switching voltage source converter.

  • DynamicLoad_TSC and Thyristor_TSC - Use these objects with the dynamic load based TSC and thyristor-based TSC.

  • ControllerTimeMode and ControllerFrequencyAndTimeMode - Use these objects with the time and frequency-and-time simulation mode.

This script also defines a fidelity variable that specifies the level of fidelity.

This example supports three different levels of fidelity:

  • Low - The example runs in frequency-and-time simulation mode. An average-value voltage source converter models the STATCOM. A dynamic load models the TSC. The sampling time is equal to 1/60 s.

  • Medium - The example runs in time simulation mode. An average-value voltage source converter models the STATCOM. A dynamic load models the TSC. The sampling time is equal to 66.67 us.

  • High - The example runs in time simulation mode. Ideal power electronic devices model the STATCOM. Thyristors and capacitor banks model the TSC. The sampling time is equal to 6.667 us.

You can change the level of fidelity in the StaticSynchronousCompensatorVariantControl script. This script configures the sampling time and simulation mode accordingly.

Plot Simulation Results from Simscape Logging

These plots show the voltage magnitude at the substation transformer primary side and reactive power that flows into the AC grid.

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