发电机故障分量负序方向保护的新判据

发电机定子绕组相间短路、匝间短路以及分支开焊 ,均为发电机内部不对称故障 ,将在发电机内部产生一个负序源。发电机外部故障或扰动 ,负序源在发电机外部。负序方向可以保护发电机内部不对称故障 ,然而 ,实际应用中的负序方向保护发生多次误动。由于它主要保护的是发电机匝间短路 ,匝间短路会在短路环路中产生极大的电流 ,但在发电机机端短路电流不大 ,迫使灵敏度整定很高 ,牺牲了安全性。本文提出的新判据在发电机外部故障或扰动时可靠地不动作 ,发电机匝间短路有较高的灵敏度。

Anew criterion for negative sequence directional protection against generator faultcomponent

The phase to phase short circuit fault, turn to turn fault and branch wielding breaking on stator winding of generator are of internal asymmetric faults of the generator. They would generate a negative sequence source inside the generator. When there is a fault outside the generator or disturbance, the negative sequence source would be outside the generator. The negative sequence directional relay can protect generator against internal asymmetric fault, but the negative sequence directional protection in practice always maloperates. Since it mainly protects the generator against turn to turn short circuit fault, and the fault would generate extreme current in the short circuit loop, the short circuit current on the generator side is not quite large. Therefore, the sensitivity has to be set to a high degree which results in the protection loss of security. The new criteria proposed in this paper makes the relay not operate firmly during fault outside the generator or disturbance, and the protection has a high sensitivity during the generator in turn to turn short circuit fault.