含电力电子变压器的配电网单相接地故障集成化消弧方法

Integrated arc suppression method of single-phase grounding fault in distribution network with power electronic transformer

在电力电子变压器输入级变流器直流侧电容中点设置接地支路,配合αβ0坐标系下的多变量解耦控制,提出一种配电网单相接地故障集成化消弧方法,该方法具备基于0轴电压调控的配电网对地参数不对称补偿、单相接地故障选相、自适应消弧功能和基于α、β轴电压调控的源端功率平衡功能。配电网正常运行时,实时监测配电网对地参数不对称引起的中性点电位偏移,根据偏移量计算补偿电流并将其注入配电网消除中性点电位偏移。配电网发生单相接地故障时,通过对比零序电压与三相电压间的关系辨识故障相,并以零序电压幅值为投切条件实现自适应消弧;通过对源端功率的实时补偿抑制因负荷投切或故障导致的功率振荡。MATLAB/Simulink仿真结果验证了所提集成化消弧方法的可行性和有效性。

With the grounding branch set in the middle point of the capacitors on DC side of the input converter of the power electronic transformer,and combining with the multivariable decoupling control under αβ0 coordinate system,the integrated arc suppression method for single-phase grounding fault in distribution network is proposed,which has the functions of distribution network asymmetry parameter compensation,single-phase grounding fault phase selection and adaptive arc suppression based on 0 axis voltage regulation,and the function of source-side power balance based on α axis and β axis voltage regulation. Under the normal operation of distribution network,the neutral point potential deviation caused by the asymmetry of distribution network parameters to ground is monitored in real time,and the compensation current is calculated according to the deviation value and injected into distribution network to eliminate the neutral point potential deviation. When the single-phase grounding fault occurs in distribution network,the amplitude and angle relationship between zero-sequence voltage and three-phase voltage are compared to recognize the fault phase. The amplitude of zero-sequence voltage is taken as the switching condition of adaptive arc suppression. The power oscillation caused by load switching or fault is suppressed by real-time compensation for source-side power. Simulative results by MATLAB/Simulink validate the feasibility and effectiveness of the proposed integrated arc suppression method.