基于RTDS的配电网小电流接地系统谐振分析

Resonance Analysis of Small Current Grounding System in Distribution Network Based on RTDS

针对实际发生的几起消弧线圈接地系统电压波形明显畸变从而造成低周保护动作的情况进行了分析,并利用MATLAB计算了各相电压的能量频谱。频谱分析表明,各相电压除基波外,能量最大的分量与零序电压回路中波形频率基本一致,且多次的电压波形畸变均发生在接地故障切除之后;进而分析推测电压波形的畸变是线路电容与消弧线圈间的谐振造成的;根据后续跟踪现场消弧线圈实际运行情况,发现消弧线圈确实运行在极限位置,系统接近全补偿。最后,利用RTDS仿真系统建模分析,仿真结果与实际录波波形基本吻合,验证了分析结果的正确性。

Several cases of voltage waveform distortion, which causes the low cycle protection in distribution network were analyzed, and the energy spectrum of each phase resonance was calculated by MATLAB. The spectrum analysis shows that the maximum energy of each phase voltage except the fundamental wave is basically the same as the waveform frequency in the zero-sequence voltage. Moreover,multiple voltage waveform distortions occur after the ground fault cutting off,which suggests that the distortion of the voltage waveform is most likely due to the resonance between the line capacitance and the arc suppression coil. According to the follow-up tracking of actual operation of the arc suppression coil, it was found that the arc suppression coil is actually operating at the limit position. The system is actually operates in the fully compensated position. Finally, the RTDS simulation system was used to modeling this situation. The simulation results are basically consistent with the actual recorded waveforms, verifying the correctness of the analysis results.