改进有源配电网中无直流源Y型级联H桥变换器的故障电弧抑制能力并最小化所需功率

A three-phase cascaded H-bridge converter (CHC) without DC sources can be employed to suppress single-phase ground (SPG) fault arc via a Y-connection in active distribution networks. Nevertheless, its DC voltage maintenance methods lead to an error in its output zero-sequence current, which causes arc suppression failure in practice and requires a large power of the CHC. This paper proposes a novel implementation method for the Y-type CHC to improve fault arc suppression capability and minimize required output power. In this method, one CHC arm connected to the ground is controlled as a voltage source, and its output voltage vector is perpendicular to the reference vector of the zero-sequence current required for arc suppression. The other two CHC arms connected to the two non-faulty phases of distribution networks are controlled as current sources, and their output current vectors are perpendicular to the voltages across them, and the sum of their output current vectors is equal to the reference vector of the zero-sequence current required for arc suppression. Thereby, the three CHC arms only output reactive power, thus maintaining their DC sources, and the total output zero-sequence current error is eliminated. Finally, the output voltage amplitude of the voltage source is calculated to minimize the total output power of the three arms. The simulation and experimental validation demonstrate that the proposed method enhances the fault current and fault voltage suppression rate and minimizes the required power of Y-type CHC.