±800 kV雅砻江换流站BP13高压电容器不平衡电流及过电压分析

Analysis of Unbalance Current and Overvoltage of BP13 High-voltage Capacitor in ±800 kV Yalongjiang Converter Station

摘要:

滤波器的高压电容器是特高压直流输电系统中故障率相对较高的设备，通常配置不平衡保护来反映其内部的故障情况。为进一步明确高压电容器内部故障工况与不平衡电流、过电压等外部故障表现的量化关系，为实际工程不平衡保护的配置与优化提供理论支撑，文中以±800 kV雅砻江换流站BP13高压电容器为研究对象，考虑高压电容器内部部分电容单元断开、电容单元内部部分电容元件断开两类典型故障，分析推导了不平衡电流与故障单元/元件个数的对应关系，并给出了电容单元故障后高压电容器不同位置的过电压表达式。基于PSCAD/EMTDC仿真平台验证了理论推导的正确性，明确了可以导致现有三段不平衡保护动作的具体故障工况。

Abstract:

High-voltage capacitor of filter is a device with relatively high failure rate in UHVDC transmission syste, and it is usually equipped with unbalance protection to reflect its internal fault. In order to further clarify the quantitative relationship between internal fault conditions and external fault performance such as unbalanced current and overvoltage, and provide theoretical support for the configuration and optimization of unbalanced protection in practical engineering, BP13 high-voltage capacitor of ±800 kV Yalongjiang converter station is taken as the research object. Considering two typical faults, the partial capacitor unit disconnection and the partial capacitor element disconnection in capacitor unit, the corresponding relationship between the unbalance current and the number of faulty units/components is analyzed and derived, and the expressions of overvoltage at different positions of high-voltage capacitor after the capacitor unit fault are given. Based on PSCAD/EMTDC simulation platform, the correctness of theoretical derivation is verified. Finally, the specific fault conditions that can lead to the existing threesection unbalanced protection action are identified.