PMU based real-time short term voltage stability monitoring — Analysis and implementation on a real-time test bed

Voltage stability plays major role in many blackout incidents. It has been recommended to develop online tools that can assess stability of the system and help in reducing the occurrence of large scale blackouts. This paper proposes a model free algorithm that can assess the short term voltage stability of the system in real time based on voltage measurements from PMU´s. This approach uses simple calculations to determine the Lyapunov Exponent whose sign indicates the stability (negative) or instability (positive) of the system. This method is implemented in a real time cyber-physical test bed that is simulating the WECC 9 Bus system in RTDS that is interfaced with an SEL-421 PMU transmitting the voltage samples data over the Ethernet to OpenPDC which is interfaced to Matlab via a database. The setup is demonstrated and the algorithm is successful in detecting the stability of the system in real time.