Improvement and Dynamic Simulation Test of the Power Electronic Device Applied to Phase Sequence Exchange Technology

Phase sequence exchange (PSE) is a recently developed emergency control technology. PSE uses power electronic devices to switch the three-phase sequence, which reduces the power angle of the generator by 120° and prevents the system from losing stability. In this work, the structure of the PSE device is improved. Based on the original nine solid-state circuit breakers (SSCBs), three mechanical circuit breakers (MCBs) are added. Normally, the current flows through the MCBs, which greatly reduces the conduction loss of the PSE device. Once the generator is identified as being out-of-step, the MCBs quickly open to transfer the current to the SSCBs. When the power angle threshold of the PSE is reached, the SSCBs are switched to complete PSE. In this article, the transient characteristics of the current transfer and PSE processes are analyzed. Based on the real time digital simulation system (RTDS) platform, dynamic simulation tests of the improved PSE prototype are carried out under different conditions. Experiments and calculations demonstrate that the improved PSE device can meet the technical requirements of PSE, and that the conduction power loss is reduced by 96% on average.