同步发电机三阻抗元件失步保护原理的改进

对目前现场广泛应用的同步发电机三阻抗元件失步保护原理进行了分析和评价 ,在此基础上提出了具有多重启动元件、可根据频率变化量自动调节失步保护与预测启动角、并利用最小二乘法预测功角变化轨迹的改进方案。改进后的失步保护方案能够区分故障、静稳破坏以及动稳失步等情况 ,并实现发电机的失步预测功能 ,提高了失步保护的性能。对振荡中心在发电机 -变压器组外部与内部等情况进行了发电机失步预测试验 ,试验结果验证了改进方案的正确性与可行性。

Improved out-of-step protection for synchronous generator based on the three-impedance element principle

The widely applied out -of -step protection using the three -impedance element principle was analyzed to develop an improved protection principle. The improved scheme has improved functions, including multiple enabling conditions, adaptive setting of the starting protection angle in accord with the slip frequency, and prediction of the variable trajectory of the power angle using the least square method. The improved scheme can distinguish whether the out -of -step is caused by a steady stable condition or a transient instability to select the best prediction function for the out -of step. The resulting performance of the new protection scheme is then much better. Dynamic simulation experiments with oscillation centers inside or outside the generator and transformer unit verify the effectiveness of the improved principle.