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

David Stenberg ; Joakim Åkesson
Göteborg : Chalmers tekniska högskola, 2016. 64 s.
[Examensarbete på avancerad nivå]

This thesis investigates voltage instability leading to voltage collapse in PSS/E and how such scenario can be prevented by the use of a system protection model which has been proposed and developed in this thesis. The model sees the system as a whole and can initiate a system protection response based on a voltage stability indicator in parallel with signals from over excitation limiters (OELs). Three case studies were performed for evaluating two well-known voltage stability indicators in the literature, namely the Impedance Stability Index (ISI) and the Transmission Path Stability Index (TPSI). The two first studies showed that one of two methods to calculate the ISI gave a more stable result, which was selected to be used in later case studies. Both indicators were then used and evaluated in a third case study consisting of the Nordic 32-bus test system developed by Svenska Kraftnat. 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 control signals to change Automated Voltage Regulator (AVR) set-points of synchronous generators and initiate load shedding schemes. The functionality of the system protection model was successfully verified when its implementation in PSS/E was able to prevent the voltage collapse scenarios designed in the third case study. Voltage collapse in the first scenario was prevented by increasing AVR set-points when OELs were activated and the TPSI value was lower than 0.15. The second scenario was more severe and it was necessary to utilize both increasing AVR set-points and as load shedding which was initialized when the TPSI dropped below a threshold of 0.05.

Nyckelord: Voltage stability, Voltage stability indicators, Impedance stability index (ISI), Transmission path stability index (TPSI), PSS/E, System protection relay model, Automatic voltage regulator (AVR), Load shedding

Publikationen registrerades 2016-10-18. Den ändrades senast 2017-08-02

CPL ID: 243594

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