基于零序电压故障暂态分量的发电机定子单相接地保护方案研究

PROTECTION SCHEME BASED ON THE FAULT TRANSIENT COMPONENT OF ZERO-SEQUENCE VOLTAGE UNDER THE STATOR GROUND FAULT OF GENERATORS

根据发电机发生定子单相接地故障后机端和中性点零序电压故障暂态分量近似相同的特点,提出了两种形式的基于零序电压故障暂态分量的发电机定子单相接地保护方案;第一种形式将基波零序电压与三次谐波电压分开处理;第二种形式无需将两者分开,直接把机端和中性点两侧零序电压故障暂态分量的和与差做为保护动作信号与制动信号,通过比较相应信号的谱能量大小检测定子单相接地故障。文中给出了第二种判据形式的详细仿真和试验结果,分析表明:新的暂态保护判据具有很高的灵敏度和可靠性。

This paper puts forward two kinds of transient based protection scheme for the stator ground fault of generators in terms of the feature that the fault transient component of zero-sequence voltage at the neutral is approximately equal to that at the terminal. In the first kind of scheme, the fault transient components of fundamental frequency and third harmonic voltages are calculated respectively. In the second kind of scheme, the sum and difference of fault transient components at the neutral and the terminal are directly chosen as the action and restrain signals, and then their spectrum energies are compared to detect the ground fault. The simulation and experimental results of the latter scheme are given in detail in the paper, and the results verify that the proposed transient based protection is with high sensitivity and reliability.