谐振接地系统对地电容与消弧线圈电感统一测量方法

Unified measurement method for ground capacitance and arc suppression coil inductance of resonant grounding system

配电网对地电容的准确测量有助于保证消弧线圈的补偿效果,降低故障对配电网的损害。提出一种基于信号注入法与快速傅里叶变换的谐振接地系统对地电容与消弧线圈电感统一测量方法。首先建立中性点电压与系统对地电容、消弧线圈电感关系。其次向中性点接入非工频电流源,利用快速傅里叶变换得到中性点电压关于电流源频率分量,消除工频误差。然后根据等效电路实现系统对地电容与消弧线圈电感的统一测量。最后通过Simulink搭建仿真模型进行分析。结果表明,该方法适用于消弧线圈直接接地、消弧线圈并联电阻接地和串联电阻接地运行方式。三相不对称条件下,对地电容与消弧线圈电感最大误差分别为0.11%和0.1%;三相对称条件下,最大误差分别为1.3%和1.8%。

The accurate measurement of the ground capacitance is helpful to ensure the compensation effect of the arc suppression coil and reduce the damage of the fault to the distribution network.A unified measurement method for ground capacitance and arc suppression coil inductance of resonant grounding system based on signal injection method and fast Fourier transform is proposed.Firstly,the relationship between the neutral voltage and the system parameters is established.Secondly,the non-power frequency current source is connected to the neutral point,and the current source frequency component of the neutral point is obtained by using the fast Fourier transform to eliminate the power frequency error.Then the unified measurement of ground capacitance and arc suppression coil inductance is realized according to the equivalent circuit.Finally,the simulation model is built by Simulink,which shows that this method is suitable for various types of arc suppression coils.In the three-phase asymmetry condition,the maximum errors of ground capacitance and arc suppression coil inductance are 0.11%and 0.1%respectively,and the maximum errors are 1.3%and 1.8%respectively in three-phase symmetry condition.