The impact of phase sequence exchange on relay protection and its resolution schemes

Abstract

Phase sequence exchange (PSE) is a recently developed emergency control technology that uses power electronic devices to quickly change the original phase sequence connection mode of the transmission line from A‐A', B‐B', and C‐C' to A‐C', B‐A', and C‐B', thereby instantly reducing the power angle by 120° to prevent the system from falling out‐of‐step. Here, a comprehensive investigative analysis of the impact of PSE on the protection performance is presented. It is shown that PSE will cause the current differential protection and zero‐sequence current protection to maloperate, and the circuit breaker must be re‐matched after PSE. To solve these problems, it is proposed to install the PSE device between the transformer and the bus‐bar and equip it with independent protection, and protection action resolution schemes are proposed. Finally, based on the RTDS platform, a dynamic simulation test was carried out using a PSE prototype, and the results verify the impact of PSE on protection, as well as the effectiveness of the proposed resolution schemes.