抑制铁磁谐振的柔性接地装置最佳消谐电流计算与实现方法

Optimal Injection Current Calculation and Implementation of Flexible Grounding Device for Suppressing Ferromagnetic Resonance

柔性接地装置通过向配电网中性点注入电流实现零序能量泄放,是铁磁谐振抑制的有效手段。针对现有柔性接地装置消谐电流选择标准不一的问题,该文提出一种最佳消谐电流计算与实现方法。通过分析单相接地故障配电网在故障切除瞬间的等效电路,获得系统的传递函数模型,利用阻尼振动系统在临界阻尼状态时消耗能量最快的结论,计算出最快抑制铁磁谐振的消谐电阻值,进而获得柔性接地装置最佳消谐电流。针对永久性单相接地故障切除引起的铁磁谐振过电压问题,阐述柔性接地装置注入最佳消谐电流的实现流程与控制方法。仿真和实验结果表明,所提方法可在较短时间内耗尽谐振能量,从而使系统脱离谐振状态,达到快速抑制铁磁谐振过电压的效果。

The flexible grounding device realizes zerosequence energy discharge by injecting current into the neutral point of the distribution network, which is an effective mean of suppressing ferromagnetic resonance. Aiming at the problem of different selection criteria for harmonic elimination currents of existing flexible grounding devices, this paper proposes a method for calculating and implementing the best harmonic elimination current. By analyzing the equivalent circuit of the single-phase grounding fault distribution network at the moment of fault removal, the transfer function model of the system is obtained, and the conclusion that the damping vibration system consumes the fastest energy in the critical resistance state is used to calculate the fastest suppression of ferromagnetic resonance harmonic elimination resistance value, and then obtain the best harmonic elimination current of the flexible grounding device. Aiming at the problem of ferromagnetic resonance overvoltage caused by single-phase grounding fault, the realization process and control method of the flexible grounding device injecting the best harmonic elimination current are described. Simulation and experimental results show that the proposed method can deplete the resonance energy in a short time so that the system is out of resonance and achieve the effect of quickly suppressing the ferromagnetic resonance overvoltage.