暂态稳定分析中的发电机电磁功率预测研究

Study of the Electric Power Prediction of Generation Unit in Transient Stability Analysis

在二群失稳模式下 ,得出了机组电磁功率与转子相对惯性中心角的变化为正弦曲线。根据单机等面积稳定判据原理 ,采用时域仿真的办法对受扰系统进行短时间的仿真 ,根据仿真结果对机组电磁功率与转子相对角正弦曲线进行拟合 ,从而得到故障后发电机电磁功率曲线。与传统的用发电机与网络实时参数计算所得的电磁功率方法相比 ,不必进行详细长时间仿真 ,而所得到的预测值与实际计算所得值误差在± 5 %以内 ,且所得到的表达式是具有物理解析意义的。实例计算表明所提出的方法速度快且精度高 。

It is pointed out that the electric power of a generation unit varies in sine wave with the rotator angle relative to the inertia center of the system. By using single machine equal area criterion (SGEAC) in combination with the time domain simulation method, the disturbed system is simulated for a very short period of time. Based on the simulation result, the curve of the electric power of a generator unit with its rotator angle relative to the inertia center of the system is fitted. Compared with the result obtained by using the real-time parameters of the generator and electrical network, it is unnecessary to simulate the disturbed system to the instant when the system loses its stability, in order to determine whether the system is stable or not. In comparison with the actual value, the error of the proposed method is in the range of ±5%. The physical meaning of the proposed method is clear.Practical system analysis shows that the method is very efficient, and it should have wide engineering applications for on-line stability monitoring.