解耦混合坐标系并网逆变器电网同步方法

针对电网电压直流分量扰动影响电网同步精度的问题,提出一种解耦混合坐标系电网电压同步方法。首先分析了传统旋转坐标系锁相环的原理及存在的问题,在此基础上,将直流分量视为频率为"0Hz交流量谐波",并结合多旋转坐标系锁相环,提出静止坐标系结合多旋转坐标系的解耦同步方法。文中从系统稳定裕度、抗扰特性和动态性能等方面对锁相环参数进行了设计。最后在电网电压畸变不平衡且存在直流分量扰动情况下进行了仿真和实验研究。实验结果验证了所提出方法的可行性和有效性。

Decoupling Hybrid Frame Based Grid Synchronization Method for Grid-connected Inverters

The accuracy of grid synchronization is sensitive to the dc offset of grid voltage. In order to solve the problem, a decoupling hybrid frame phase-locked loop (PLL) based grid synchronization method is presented. First, the basic principle and disadvantages of the conventional synchronous frame PLL are discussed. And then, a new stationary and synchronous frame grid synchronization method is proposed by integrating the multiple synchronous frame PLL with the idea, whose dc component is considered as a 0 Hz ac harmonic. The parameters of the proposed PLL are designed from the angle of the system phase margin, disturbance rejection and dynamic performance. Finally, simulation and experimental tests are carried out under the unbalanced, distorted and dc offset conditions. The results have verified the feasibility and effectiveness of the proposed method.