基于无功功率捕捉失步解列断面的理论研究

就等值双机系统在失步振荡过程中失步断面联络线的电气量进行了研究分析。当多机电力系统失步成2组同调机群,失步断面通常是由考虑到解列后子系统的同步运行并可以将系统解列成2个同调子系统的一组联络线组成。这组联络线的电气量的共同特征主要是:失步断面联络线上有功功率周期性过零振荡;失步断面联络线上有一点(失步中心),其电压幅值的变化幅度明显大于联络线的其他地方,且距离失步中心越远,幅值变化越小,即在失步振荡过程中,失步断面联络线存在明显的电压梯度;失步过程中,无功功率由失步断面两侧流向失步断面中。利用有功过零判断振荡周期并在该周期内对无功功率进行积分,该积分值能够反映出失步断面的这些特征。基于此,提出了基于无功功率寻找失步解列断面的方法。

Theoretical Study on Capturing the Separation Interface of Out-of-step Based on Reactive Power

The characteristics of electrical parameters of separation interface are discussed when an equivalent two-machine power system is out-of-step. While a multi-machine system is out-of-step and splits into two coherent groups, the separation interface, generally composed of several tie-lines, will disconnect the whole transmission network into two coherent electrical islands. The characteristics of the separation interface tie-lines are as follows. First, the active power flow crosses zero and oscillates periodically. Secondly, there is one point, the center of out-of-step, existing in the interconnector whose voltage amplitude change is the largest when compared with those of other points, viz. a large voltage gradient in separation interface occurs during the course of out-of-step. Thirdly, reactive power flows from both sides to the interior of the separation interface. The integral value of reactive power in one period of out-of-step reflects the characteristics of separation interface by adopting the first characteristic above. Thus the reactive power based method of capturing separation interface is presented.