An investigation into WAMS-based Under-frequency load shedding

Traditional Under-frequency load shedding (UFLS) relays have fixed parameters thus are not adaptive to system operating conditions, they may cause either over or under shedding. As the deployment of wide area measurement system (WAMS) spreads out, a good prospect for a global adaptive UFLS scheme is brought out. In this paper, a time-based adaptive UFLS scheme is presented. The motivation is to optimize the load shed parameters for rapid response to serious crisis. Then based on the system frequency response (SFR) model, an “Implicit Enumeration with Adaptive Discretization” algorithm is introduced to facilitate the design. Simulations on a real, small system weakly connected to the Eastern China system have solidified the effectiveness of the proposed scheme.