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数据采样异常是引起电力系统误操作的主要原因,而在短数据窗下较难区分电气量的异常采样值和故障时的正常采样值。首先分析了电力系统正常运行及故障下电流、电压波形的特点,指出波形除若干间断点外在其他任意点处连续可导且导数同样分段连续,可利用这一特性判断采样值是否异常。因采样数据采样步长相对固定,波形在某点连续所要求的导数存在性,可通过与其前后相邻两点的差分获得。进一步在设定合适的差分误差门槛基础上,判断采样值是否异常,简称为采样值的3点连续有效判别法。给出了差分误差门槛的具体确定方法,分析了该方法应用中的几个具体问题,并用仿真验证了方法的可行性。
Data sampling anomaly is the main cause of power system misoperation, while under the short data window, it is difficult to distinguish the abnormal sampling value of the electrical quantity and the normal sampling value when the fault occurs. Firstly, the characteristics of current and voltage waveform under normal operation and fault of power system are analyzed. It is pointed out that the waveform can be used continuously to judge whether the sampling value is abnormal or not. Due to the relative fixed sample-data sampling step, the continuity of the required derivative of the waveform at a certain point can be obtained by the difference between two adjacent points. Further to determine the appropriate differential error threshold, based on the judge whether the sample value is abnormal, referred to as the sample value of 3 consecutive effective discriminant. The method to determine the threshold of differential error is given. Several specific problems in the application of the method are analyzed. The feasibility of the method is verified by simulation.