PMU-based Online Monitoring of Short-term Voltage Stability using Lyapunov Exponents

Abstract

Online monitoring of voltage stability is an important task to identify operating conditions of the system that lead to instability and/or voltage collapse and to decide on automatic corrective control actions. In recent years, the installation of phasor measurement units (PMU) in power systems has increased significantly, which is why a large amount of information in real time is available for online analysis of the dynamic response to contingencies. This paper proposes a new methodology based on PMU for online monitoring of short-term voltage stability under large disturbances from estimating the maximal Lyapunov exponent (MEL) in the post-contingency voltage time series. The methodology includes an offline procedure with a stochastic approach based on the Monte Carlo simulation and the particle swarm optimization (PSO) method to adjust the embedding parameters of the MEL estimation algorithm. Case studies are analyzed in the New England 39-bus test system to present the performance of the MEL estimation with different embedding parameters and to demonstrate the effectiveness of the proposed methodology for monitoring short-term voltage stability under different operating conditions.