Modeling and Simulation Research on Symmetrical Fault Characteristics on AC Side of Static Frequency Converter of Pumped Storage Unit

The Static Frequency Converter (SFC) assumes a pivotal role in the initiation procedure of large synchronous motor within pumped storage unit. Based on fully studying the working principle and control strategy of SFC, this study combined with C language to write commutation control subroutine and built a complete electromagnetic transient simulation model of stationary frequency conversion start-up process of pumped storage unit on PSCAD/EMTDC simulation platform, which serves as a fundamental cornerstone for the investigation of dynamic response characteristics pertaining to the initiation of SFC in pumped storage unit. Leveraging the established electromagnetic transient simulation model, various fault scenarios are configured for distinct commutation control phases within SFC. Symmetrical faults on the AC side of SFC are simulated during intermittent commutation and natural commutation stages. Moreover, a comprehensive analysis of the symmetrical fault characteristics across diverse positions and stages is conducted, with a particular emphasis on their repercussions on the initiation process of the pumped storage unit. It offers a robust foundation for the exploration of fault diagnosis, fault recovery strategies, and the formulation of protection principles applicable to static frequency converter.