电压互感器和电流互感器暂态特性对距离保护算法的影响

对距离保护暂态超越产生的原因进行了详细分析，并给出了结论．对于采用解微分方程算法的距离保护，当电容式电压互感器（CVT）和电流互感器（CT）暂态特性一致时，它们对解微分方程算法没有影响，反之则会引起暂态超越．通过建立两者的数学模型，分析并比较两者在传递非周期分量时暂态特性的差异发现，由于CVT和CT的传变特性不一致而引起的二次侧电压和电流中非周期分量无法平衡是导致距离保护暂态超越的根本原因．EMTP故障仿真和现场录波试验表明，CVT和CT的非周期分量衰减时间分别为10ms和40ms，即CVT后非周期分量比CT后非周期分量衰减快，因而会导致距离保护因为暂态超越而误动作．

Influence of Transient Characteristics of Capacitor Voltage Transformer and Current Transformer on Distance Protection

The mechanism of transient overreach in the distance relays is analyzed for the distance protection by solving differential equations,It is revealed that if the coincident transient characteristics remain in capactor voltage transformer(CVT) and current transformer(CT),and the transient overreach phenomenon does not arise,while the difference of transient characteristics between CVT and CT leads to a transient overreach,and the unbalanced non-period component primarily induces the transient overreach.EMTP simulation shows that the decay time of non-period component of CVT of 10 ms is much shorter than 40 ms of CT,thus the distance relays operate by mistake.