基于瞬时频率的保护用振荡建模新方法

Instantaneous Frequency Based Power System Oscillation Modeling Method for Relay Protection

现有振荡模型的建立都是通过改变"0-t时间段的平均频率"来实现,不能直接反映系统的实际运行状态。为解决该问题,提出了一种基于瞬时频率的振荡建模新方法,通过对瞬时频率的变化在约束条件下进行拟合,能准确地仿真出实际系统的振荡过程,不受"0-t时间段平均频率"的束缚。利用该方法,建立了一种全过程振荡模型,通过MATLAB中的电力系统仿真软件包PSB对其振荡以及振荡中发生故障的情况进行了仿真。仿真结果表明,该模型可以准确反映预先设置的频率变化规律,非常适合于继电保护的研究。

Currently available oscillation modeling methods are all based on changing the ＂average frequency of 0-t interval＂, which cannot directly reflect the actual state of a power system. To solve the problem, this paper proposes a new modeling method based on instantaneous frequency. By fitting the changes of instantaneous frequency under constraint conditions, the method can accurately simulate the oscillation process of a real system without introducing the ＂ average frequency of 0-t interval＂. With this method, an oscillation model reflecting the whole process is developed, with two typical cases of oscillation （without/with fault） simulated using the power system block （PSB） in MATLAB software. The simulation results show that this model can satisfactorily match the preset curve of frequency during oscillation, and is ideally suitable for research on the performance evaluation of relay protection.