Rogowski式电流互感器对雷击过电压干扰的研究

Study on Disturbance of Lightning Strike on Rogowski Current Transformer

已有的Rogowski线圈式电流互感器在运行中存在长期稳定性和测量准确度不高等问题。针对实际运行过程中电力系统遭受雷击或者出现过电压时,Rogowski式电流互感器由于本身结构导致其二次侧电流发生较大变化,造成保护装置误动的现象进行了原理分析,给出相应的解决方法。针对常用的Fourier变换不能很好地区分故障电流与雷击产生电流的问题,利用小波分析对正常工作时的测量电流、雷击过电压导致测量电流增大和故障造成的测量电流增大进行分析,利用之间的不同,来判断电流互感器二次侧电流增大的原因。最终得出,通过小波分析的细节图能够很好地将故障造成的测量电流值过大与雷击过电压造成的测量电流值过大区分开来。

Many problems such as long-term stability and inaccurate measurement exist in the actual running of Rogowski coil current transformer. When the power system is struck by lightning strike or over-voltage, the secondary side current of the Rogowski current transformer is significantly interfered because of its structure, which causes the mis-operation of the protection device. In this paper, the principle of the phenomenon is analyzed, and appropriate solution is put forward. To deal with the problem that the commonly used Fourier Transform cannot well distinguish the fault current and lightning current, wavelet transform method is used to analyze the measured current in normal conditions, measured current increase caused by lightning strike and grid faults. Their difference is used to decide whether the current increase is caused by lightning strike or grid faults. And according to the results, the differences will be found which can be used to judge whether the increased current is caused by lightning strike or the grid faults.