一种切换采样原理转子接地保护算法的研究

Study of Rotor Earth-Fault Protection With Switch Sampling Principle

切换采样转子一点接地保护,通过两个静态开关一开一合建立两组方程来求解接地电阻与位置。本文针对一种实施方案,提出了可以将两开关同时断开建立起第三组方程。通过数值计算,分析了在不同接地点,不同接地电阻情况下,接地电阻对各测量电流的偏导数大小,得出在接地点位置不同情况下,选用不同方程计算接地电阻,可以减小电流测量误差对接地电阻计算的影响,在励磁电压低,接地电阻小的情况下,效果更加明显。静模试验也证实了上述结果。

Commonly, by opening one switch and closing the other, two group equations are set up to measure rotor earth-fault resistance in the rotor earth-fault protection with switch sampling principle. This paper advances setting up a third group equations by opening both switches. By analyzing the partial derivative of earth-fault resistance versus each sampling current at different earth-fault location and different magnitude of earth-fault resistance, an approach is presented which measure the earth-fault resistance by selecting two proper group equations at different earth-fault location. Experimental results demonstrate that the approach can reduce the influence of sampling current error, especially in low exciting voltage and low earth-fault resistance condition.