大规模电网中低频振荡扰动源的定位方法

Locating Method of Disturbance Source of Low Frequency Oscillation in Large Scale Power Grid

由于中国电网规模庞大,低频振荡现象时有发生,如何快速确定低频振荡扰动源并及时将其切除,对保障电网的安全稳定运行意义重大。当电网中发生低频振荡时,根据传播到电网中不同位置的特殊形状扰动行波具有的相似性特点,提出一种比较多点测量数据波形相似度以确定低频振荡扰动源位置的定位方法,针对在电网中不同地点一段时间内同时采样的电压数据,利用希尔波特(Hilbert)变换提取各采样点的电压扰动变量并将其传送至监控单元,在监控单元利用定义的顺序相似度函数提取扰动行波通过各相邻采样点间的时差和先后次序,利用各采样点间已知的线路长度计算波速并确定低频振荡扰动源的位置。通过一个7机无穷大系统模型的仿真分析,验证该方法的正确性和准确性。理论分析和仿真结果表明:该方法能够快速确定电网中低频扰动源的位置;而且所需的采样测量单元数量少,能够节省大量投资。

When there was a lower frequency oscillation in power grid, the transient wave with special form propagates everywhere in the transmission line. A new method for locating the disturbance source of low frequency oscillation was proposed in the paper based on the correlation function of obtained disturbance voltage variable. The voltage of same phase at different places in power grid was measured during the same time when low frequency oscillation was taking place. The disturbance variable of voltage was obtained by Hilbert transform and sent to the monitor unit. The time delay and sequence between the two voltage measuring units were calculated by correlated function in monitor unit when the disturbance voltage passed through them. The location of disturbance source of low frequency oscillation was calculated by the length of transmission line and the time delay. The validity of this proposed method was verified by a simulating model with seven generators and an infinite system. The results of theoretical analysis and simulating test show that the location of low frequency oscillation source can be determined quickly. At the same time, the number of required measuring units is very small and huge investment in it can be reduced.