交流滤波器高压电容器不平衡保护新原理

基于目前应用于直流输电系统的交流滤波器电容器不平衡保护原理，指出当前电容器不平衡保护原理中存在的缺陷，提出了以电容器不平衡电流与流过滤波器的穿越电流比值作为交流滤波器电容器不平衡保护判据的新方法，并推导了不平衡保护定值的计算公式。文中以高岭背靠背直流工程数据为基础，应用电磁暂态计算软件EMTDC/PSCAD进行仿真验证，证明了该方法的合理性及有效性，并在不平衡保护的实现和运行方面提出几点建议。该方法已成功应用于高岭背靠背直流工程，对直流输电系统规划设计及现场运行具有实际指导意义。

New Principle of Unbalance Current Protection for Capacitor of AC Filter

Based on an unbalance current protection principle for AC filter used in DC transmission system,some shortcomings on the existing principles are pointed out.A new principle suitable for the unbalance current protection is proposed,in which the ratio between the unbalance current and the traversing current flowing through AC filter is used as an unbalance current protection criterion for AC filter.The calculation formula for the unbalance protection setting value is deduced.Based on the concrete parameters of the Gaoling BTB HVDC project,the detailed simulation was completed with electromagnetic transient calculation software EMTDC/PSCAD in order to prove rationality and validity of the new principle.In addition,some useful suggestions are described for implementation and application of the unbalance protection.This method has been put into successful operation in Gaoling BTB HVDC project now,which is in favor of HVDC system design and operation on site.