测量阻抗的振荡轨迹识别

Recognition of oscillation trajectory for measured impedance

振荡是电力系统中一种严重的异常运行状态,容易引起距离保护的误动,而振荡轨迹的识别是研究振荡对距离保护影响的理论基础,经典的振荡轨迹分析一般是基于系统两侧电势幅值相等的假定条件进行的。所提方法不进行任何假设,基于测量阻抗的数学解析式,对测量阻抗的振荡轨迹进行了详细推导。推导结果显示,在任意系统阻抗角下,系统两侧电势不等时振荡轨迹为圆,并确定了振荡圆心和半径。PSCAD/EMTDC仿真验证了所提方法的正确性。

Power oscillation is a seriously abnormal operating state of power system,which may easily cause the misoperation of distance protection. The oscillation trajectory recognition is the theoretical basis for studying the effect of power oscillation on the distance protection and the classic oscillation trajectory analysis is normally based on the assumption that the potential amplitudes at both system sides are equal. Without any assumption,a method based on the analysis formula of measured impedance is proposed to deduce its oscillation trajectory. Analysis results show that,the oscillation trajectory is a circle with determined center and radius when the potential amplitudes at both system sides are unequal for any system impedance angle. The correctness of the proposed method is verified by PSCAD/EMTDC simulation.