基于故障分支快速辨识的T型高压输电线路故障定位新算法

传统T型高压线路故障测距方法在T节点附近发生故障时有测距死区,针对这一不足,根据两端测得故障点处正序电压相等推导出一种新的测距函数进行故障分支判断。在故障支路上,测距函数相位值单调且在首末两处的函数相位值相差大约180°;正常支路上,测距函数相位值也单调但在首末两处的函数相位值大约相等。基于测距函数的相位在首末两处的相位相差的大小这一特性作为故障分支判据,进而利用故障距离的解析表达式求解故障距离。该方法较好地克服了传统方法在T节点附近不能可靠识别故障支路的缺点,并且无需判别故障类型,只需代入相应的公式计算几个点即可得到故障距离,程序实现简单,计算速度快。本算法的测距精度理论上不受故障类型、过渡电阻、运行方式等影响。EMTP仿真结果验证了所述算法的正确性和高精度。

A New Fault Location Algorithm for High-voltage Three-terminal Transmission Lines Based on Fault Branch Fast Identification

The traditional method for fault location of T-type lines is not able to identify the fault section correctly when the fault occurs near the T-type node, thus failing to locate the fault. To solve this problem, a novel branch identification criterion algorithm is proposed based on the principle of equal positive sequence voltage detected at both ends. It is concluded that the fault location function is monotonical and at the head and end the two values differ by approximately 180° at the fault branch, but the fault location function is also monotonical and at the head and end the two values are approximately equal at the healthy branch. With the phase difference in magnitude between the fault location function at the head and that at the end as the criterion for fault branch, the fault distance is solved using the analytical expression for fault distance. This branch identification criterion algorithm has remedied the drawback of traditional fault location methods. Despite the dead zone of fault location, no type identification is required, while the fault distance is obtained simply by calculating a few points with the corresponding formula. With its simple procedure and fast implementation, the proposed algorithm accuracy is in theory independent of fault type, fault resistance at fault point and operation mode, etc. The EMTP simulation results verify the validity and high precision of the algorithm.