一种中性线串接电容的LC耦合型配电网静止同步补偿器拓扑结构

Research on a New LC-DSTATCOM Topology of Neutral Line Connected Capacitor

在对三相四线制低压配电系统电能质量问题进行综合治理时,为减少开关模块的电压应力和损耗,并提高补偿装置性价比和可靠性,提出一种新型中性线串接电容的LC耦合型配电网静止同步补偿器（LC-coupling static synchronous compensator,LC-DSTATCOM）。该新型补偿器在三桥臂逆变器并网支路上串联电容器,使得并网支路上基波阻抗呈容性,可以降低直流电容电压,从而减小绝缘栅双极型晶体管（insulated gate bipolar transistor,IGBT）的开关应力和损耗,降低系统运行成本;在直流侧电容负极端至中性线之间串接一个小型交流电容,可以通过分流作用使零序电流在负载侧和逆变器之间形成一个回路,这样就能显著减少流回电源侧的零序电流,从而达到补偿零序电流的目的。对所提出的拓扑结构进行了详细的分析和建模,并讨论了相关的参数设计。最后,仿真和实验结果验证了所提拓扑结构的正确性和有效性。

In order to reduce voltage stress and power loss of switching module and improve cost-effectiveness of compensation devices and reliability in comprehensive management of three-phase four-wire LV distribution system, a new LC-coupling static synchronous compensator（LC-DSTATCOM） of neutral line connected capacitor for distribution network is proposed. The new compensator is connected in series with a capacitor respectively in the three-leg inverter grid branch, to make the parallel impedance on the grid branch capacitive, thus reducing DC side voltage, IGBT switching stress and power loss. The operation cost therefore is decreased. A small AC capacitor is connected in series between the negative side of the DC side capacitor and the neutral line, and a loop between the load side and the inverter is formed through diversion of zero sequence current. So the zero sequence current is greatly reduced, and the purpose of stabilizing zero sequence current is achieved. The proposed topology is analyzed and modeled, and related parameter design is discussed. Finally, simulation and experimental results verify correctness and effectiveness of the proposed scheme.