A Dynamic Equivalent Method for Electromagnetic Transient Simulation and Its Application in East China Power Grid

Abstract

There is an inherent limitation when unbalanced faults in AC system are studied in large scale AC/DC power systems with electromechanical transient simulation. In order to make the electromagnetic transient simulation which is accurate in these situations possible, dynamic reduction must to be done. A method based on support strength of generators is proposed. According to the connection form of low-voltage network with 500kV skeleton buses and whether there are generators in it, three reduction schemes are used to replace the corresponding low-voltage network. The dynamic parameters of equivalent generators are obtained by a time domain aggregation method. The equivalent results of planning data of East China Power Grid in 2020 show that, the method has high accuracy in power flow analysis as well as short circuit calculation. The proposed method greatly simplifies the original system while the characteristic of dynamic response remains.