A Model-free Approach for Short Term Voltage Stability Assessment of Power System and Individual Bus

The voltage evolution of power system after large disturbance has chaotic behavior and uncertainty. It is necessary to evaluate the short-term voltage stability of power system. However, current assessment methods rely on system models and are computationally time-consuming, which are not suitable for online assessment. In this paper, we find that nonlinear dynamics theory can effectively solve this problem. Therefore, we use the Lyapunov exponent in nonlinear dynamics as a criterion for evaluating short-term voltage stability. Based on the Lyapunov Exponent, we evaluate the voltage stability of the whole system and the voltage stability of individual buses. Further, we propose a partition method for the unstable region in the power grid and locate the severely unstable bus. Finally, we provide simulation results and performance comparison in IEEE-14 bus system and the IEEE39 bus system, which are used to demonstrate the effectiveness of the proposed method.