柔性接地配电网故障复合消弧与铁磁谐振主动抑制研究

柔性接地方式采用电力电子化手段灵活调节配电网零序电压，是智能配电网的研究热点。现有柔性接地配电系统在复杂接地故障工况时难以有效消弧，在主动抑制铁磁谐振过电压方面的潜力未被挖掘。为此，本项目将融合有源电压消弧和电流消弧方式，提出有源消弧方法的适用性判据和复合消弧策略，解决不对称配电网高阻接地故障相辨识和重载线路低阻接地故障消弧难题；揭示单相接地故障期间柔性接地系统暂态能量的演变规律，提出柔性接地配电网主动抑制铁磁谐振的控制模式切换策略，实现故障后主动避免或抑制铁磁谐振；提取故障配电网阻抗模型和扰动特征，提出柔性接地控制系统主电路结构优化与稳定控制方法，解决长距离馈线接地故障时柔性接地系统稳定控制难题。项目将解决配电网单相接地故障消弧与铁磁谐振主动抑制相协调的问题，完善配电网故障消弧与铁磁谐振抑制理论，实现复杂接地故障配电网可靠消弧与铁磁谐振主动抑制，提高配电网自愈能力和供电可靠性。

Flexible grounding method adopts power electronics devices to flexibly regulate zero-sequence voltage, which is a hot spot in smart distribution network research field. The state-of-the-art flexible grounding distributed system faces the difficulty of effectively extinguishing ground-fault arcs in complicated grounding fault conditions. Moreover, its potential of actively suppressing ferro-resonance overvoltage is not explored yet. For these purposes, this project will firstly blend active voltage and current arc-suppression methods, propose the applicability judgement of active method and complex arc-suppression method to accurately recognize the faulty phase in asymmetrical distribution network subject to high-resistance ground fault and reliably extinguish ground-fault arcs in heavy load distribution lines subject to low-resistance ground fault. This project will then reveal the variation discipline of zero-sequence transient energy after ground fault, propose a control methods switch strategy to active suppress ferro-resonance. Finally, this project will extract the impedance model and disturbance characteristics of the faulty distribution network, propose main circuit and control parameters optimization method to realize stable control of the flexible control system under ground-fault condition subject to long distance distribution lines. Conclusively, this project will improve the theory of arc and ferro-resonance suppression, realize reliable arc distinguishing and active ferro-resonance suppression, which will further enhance the ability of self-heal and power distribution reliability.