Characteristic Research of Commutation Failure for Hybrid AC/DC System

Commutation failure is a kind of common failure type for Ultra High Voltage Direct Current (UHVDC) system, and its influence on hybrid AC/DC system are widely studued by researchers. Based on the detailed hybrid AC/DC system model, established in electromagnetic transient simulation software PSCAD/EMTDC, dynamic characteristics of the hybrid system under commutation failure, and key influence factors for commutation failure degree, are researched in this paper. In the model, UHVDC is connected to the AC system through double circuit transmission lines. Research results show that, the established hybrid AC/DC system model in this paper can reflect electromagnetic properties of different operation conditions, especially for commutation failure condition, and strength of AC system, fault type, fault resistance and other factors will have an apparent impact on commutation failure degree, laying solid foundations for subsequent protection related issues in hybrid AC/DC system.