基于级联H桥变流器和dq变换的配电网故障柔性消弧方法

为解决配电网单相接地故障消弧的难题,提出一种基于级联H桥变流器和dq变换的柔性消弧新方法。配电网的三相经级联H桥变流器接地,柔性控制非故障相变流器经连接电感注入电流,补偿接地点的电弧电流,抑制故障相恢复电压,促进电弧快速熄灭、不易重燃。为了实现对稳定性和间歇性电弧接地故障电流的全补偿,结合级联H桥变流器的特性,提出一种基于dq坐标变换的故障谐波及暂态电流分量的检测方法。根据级联H桥变流器注入电流对接地故障电流、故障相恢复电压的作用机理,研究各类电弧接地故障的统一柔性消弧方法,仿真结果表明所提消弧方法的有效性,可以提高配电网接地故障熄弧率,促进柔性交流输电(FACTS)技术在智能配电网接地故障保护中的研究与应用。

Fault Flexible Arc Suppression Approach Based on Cascaded H-Bridge Converters and dq Coordinate Transformation for Distribution Network

To solve the problem of arc suppression under the single-phase grounding fault in distribution network, a novel approach based on cascaded H-bridge converters and dq reference frame transformation is proposed. A flexible grounding mode using three-phase cascaded H-bridge converter is firstly adopted in network. The current injected in non-fault phases can compensate the arc current at fault point and suppress the recovery voltage of fault phase. It could promote the rapid extinguishment of arc and make it restrike hardly. Then combined with the features of cascaded H-bridge converter, a new detecting method for harmonic and transient components of fault current based on dq reference frame transformation has been proposed. This method can realize the full current compensation in the cases of both stable and intermittent arc grounding faults. According to the mechanisms of current injected by cascaded H-bridge converter on fault current and fault phase recovery voltage, a unified arc suppression method about various arc grounding faults has been studied. Simulation results show the proposed approach is effective, which can improve arc extinguishment rate, promote the study and application of FACTS technique in grounding fault protection of smart power distribution network.