Approach to Enhance the Robustness on PMU based Power System Dynamic Equivalent Modeling

Due to the maturity of wide area measurement technology, PMU based Dynamic Equivalent Modeling Method (PDM) has been wildly used in large scale power system modeling. However, traditional “event-based” PDM equivalent model may face serious robustness issues: though derived equivalent models show the good ability on reproduction of the system behaviors under recorded events where they derived from, they may not work well for other possible disturbances. In this paper, to improve the robustness of equivalent model, a novel method on dynamic equivalent modeling of power system is proposed. Based on the result of coherency identification, generators inside the equivalent system can be aggregated into different coherent subgroups and represented by multi-machine equivalent model. Key parameter selection, which can shrink the scale of identified parameters, is designed to avoid multiple solutions of the equivalent model. Moreover, a multiobjective parameter identification algorithm is developed to fully consider the PMU measurements in different system events. In addition, hybrid dynamic simulation is performed so that each equivalent sub-model can be identified separately. Finally, the efficiency of the proposed method is verified in an actual power grids in China.