A Dynamic Equivalent Method of Three-Sequence Network for Electromagnetic Transient Simulation

Electromagnetic transient simulation can accurately simulate the dynamic characteristics of AC/DC power system under asymmetric faults. In order to reduce the amount of simulating calculation and improve the simulation efficiency, it is necessary to simplify the large-scale power system. A dynamic equivalent method of three-sequence network for electromagnetic transient simulation is proposed. Based on the physical equivalence dynamic reduction technique, this method improves the standard equivalent structures of low-voltage networks, takes into account the negative sequence and zero sequence currents under asymmetric short-circuit faults, and adopts a practical engineering method of parameter aggregation of equivalent generators and selection of controller models. The equivalent method does not produce negative resistance branches in the simplification process, and avoids the emergence of equivalent transformers with negative resistance or reactance. Finally, the proposed method is applied to the simplification of Zhejiang Power Grid. Simulation results verify the effectiveness of the proposed method.