三相并网逆变器公共耦合点电压控制研究

Research on PCC voltage control of three-phase grid-connected inverter

现代电力设备负荷变化将影响系统公共耦合点电压质量,降低并网系统运行可靠性。根据不同的线路阻抗性质,并网逆变器可以注入一定有功或无功功率实现公共耦合电压恢复控制。本文首先从功率流角度分析了系统线路阻抗和负荷变化对公共耦合点电压峰值变化的影响,而后利用并网电流在不同线路阻抗上的压降补偿作用提出两种电流补偿闭环控制方案,实现负荷变化情况下公共耦合点电压快速恢复。最后搭建了并网逆变器实验样机并进行了公共耦合点电压恢复实验研究,实验结果证明所提方案可以实现负荷变化情况下电压快速恢复。

The load profile variation of the modern electrical equipments has a negative effect on the voltage quality at the point of common coupling,which degrades the reliability of grid-connected sensitive loads. The voltage regulation at the point of common coupling can be achieved by dynamically controlling the real or reactive power injected to the utility by the grid-connected inverter based on the types of line impedances. Firstly,the inherent relationship between voltage and load variation by considering the network impedance impact is discussed. Secondly,two compensated control strategies are evaluated to identify the compensator for the closed-loop controller to recover the voltage with a fast dynamic response speed when the load profile changes. Finally,the prototype of grid-connected inverter is built and the experimental tests are conducted to verify the effectiveness of the proposed method.