基于动态虚拟磁通分析的CT饱和识别方案研究

Research on the method to identify CT saturation based on dynamic virtual magnetic flux

阐述了CT的工作原理,分析了CT饱和时铁芯磁通的特征,提出了基于动态虚拟磁通分析的CT饱和识别方案。该方案通过二次电流与CT铁芯磁通存在的联系计算动态虚拟磁通,根据CT饱和时饱和区磁通达到最大值与电流过零时刻的相对时间变短进行CT饱和识别,根据CT饱和时线性区磁通小于饱和区的磁通进行线性区识别。该方案利用磁通特征识别饱和及线性区,不受非周期分量、高次谐波等电流特征的影响。经仿真验证,该方案能够快速判断CT是否发生饱和,准确定位线性区起止点,原理简单,实现方便,具有实际应用价值。

After analyzing the characteristic of core magnetic flux of CT during CT saturation, a new method based on dynamic virtual magnetic flux to identify CT saturation is proposed. The method calculates the dynamic virtual magnetic flux with secondary current with the relations between secondary current and magnetic flux. The method can identify CT saturation with the characteristic of core magnetic flux that the time between the starting of CT saturation when the magnetic flux reaches the maximum and zero time of secondary current is shorter, and identify linear data with that value of core magnetic flux during linear data is less than it during CT saturation. The method uses the characteristic of core magnetic flux to identify CT saturation, which will not affected by the characteristic of secondary current such as aperiodic component and high harmonics. The simulation results show that the proposed method can quickly identify CT saturation, position the start and end point of linear data accurately, which has simple principle, is easy to realize and has practical application value.