Development of a user-defined system protection model against voltage collapse in PSS/E

Paper in proceeding, 2023

This paper investigates the voltage instability problem leading to a voltage collapse and how such scenario can be prevented by the use of a user-defined system protection model in PSS/E. The model continuously monitors in real-time the system as a whole and can initiate a system protection control actions when a prominent voltage collapse is detected based on a voltage stability indicator in parallel with signals from overexcitation limiters (OELs). Two well-known voltage stability indicators have been evaluated, namely the Impedance Stability Index (ISI) and the Transmission Path Stability Index (TPSI). Both indicators has been evaluated in a case study using the Nordic-32 test system. In this case study, two separate contingency scenarios were designed to cause a voltage collapse. It was found that the calculations of the ISI were time consuming and did not indicate the margin to voltage collapse as clearly as the TPSI did. The TPSI and signals from OELs were used as input signals in the system protection model designed to protect the power system. The model was designed to generate the control signals to change Automated Voltage Regulator (AVR) set-points of synchronous generators and initiate load shedding control actions. The functionality of the system protection model was successfully verified when it was able to prevent the voltage collapse scenarios designed in the case study.