The broadband frequency characteristics of major equipment in the ±800 kV converter station and their influences to the short-circuit fault transient

Abstract

Due to the wide application of high-order resonant and nonlinear electric equipment in the UHVDC converter station, the electromagnetic transient process is a complex issue during the short-circuit fault transient of the system caused by lightning strike or other reasons. In this study, firstly, an operating ±800kV DC line is artificially short-circuited to simulate the flashover fault process. The instantaneous voltages and currents and the electrical fields are measured by advanced sensors and high sampling rate recording devices at different points in the converter station, in order to comprehensively study the high-frequency characteristics of the UHVDC system. Then, the portal impedances of the major UHVDC equipment as well as the stray parameters are systematically measured in an actual ±800kV station. Based on the data measured, the accurate high-frequency characteristics of the ±800kV converter station are analyzed. The results of the study can be used to guide the EMC and relay protection designs of the UHVDC converter station, so that the stability of the system can be improved.