适用于母线保护的负序电压提取及闭锁方案

为解决复合电压闭锁元件中负序电压提取快速性与准确性之间的矛盾,研究了基于瞬时对称分量法和半周积分法的负序电压提取方法。通过在故障启动时刻投入负序电压瞬时值提取算法,消除了由于母线电压突变造成的瞬时值提取误差。设计了采用该方法的母线保护复合电压闭锁方案,并与母线差动保护相配合:在故障启动后1个周期内,采用改进瞬时对称分量法和半周积分法提取负序电压有效值,与采样值差动元件相配合;故障启动满1周期后,采用全周算法和序分量分解法提取负序电压有效值,与相量差动元件相配合。通过数字仿真和RTDS实验验证,整个方案可大幅减小负序电压计算的暂态过程误差,有效提高区内故障时负序电压元件的开放速度,有利于改善复压元件的灵敏度。

Negative-sequence voltage extraction and blocking scheme for bus protection

In order to coordinate the accuracy and rapidity of negative-sequence voltage extraction from the composite voltage blocking element, a method of negative-sequence voltage extraction based on the instantaneous symmetrical component method and the half-cycle integral method is proposed, which extracts the instantaneous negative-sequence voltage at the fault startup instant to eliminate the extraction error due to the sudden change of bus voltage. A composite voltage blocking scheme of bus protection based on the proposed method is designed and cooperated with the bus differential protection, which applies the improved instantaneous symmetrical component method and the half-cycle integral method to extract the negative-sequence voltage and cooperates with the sample differential element during the first cycle after the fault startup, and afterwards, applies the whole-cycle algorithm and the sequence component decomposition to extract the negative-sequence voltage and cooperates with the phasor differential element. Digital simulation and RTDS experiment verify that, the calculation error of transient negative-sequence voltage is significantly reduced, the response speed of negative-sequence voltage element for in-zone faults is effectively increased, and the sensitivity of composite voltage element is improved.