基于重复PI控制的光伏并网逆变器的研究

针对单纯PI控制的缺点,对光伏并网系统中逆变器的控制进行了改进,提出重复控制和PI控制相结合的电流跟踪控制策略。重复控制可以抑制网侧和负载侧对并网输出电流的周期性扰动,降低并网电流的总谐波畸变系数;PI控制则利用偏差调节原理,使逆变器输出并网电流实时跟踪参考正弦给定信号。此外,加入预测算法以便消除逆变器开关器件和输出滤波网络的延迟影响,使并网电流与电网电压相位趋于一致。实验结果表明,新的控制策略可有效改善并网电流波形,同时可保证逆变器输出电流与电网电压同频同相。

Study on Photovoltaic Grid-connected Inverter based on Repetitive-PI Control

Aiming at the shortcomings of PI controller,this paper engaged in improving the control of photovoltaic grid-con-nected inverter and put forward a current tracking control strategy which combines PI control with repetitive control.The repetitive control was able to restrain the periodic disturbance of the load and power grid,and also it can evidently reduce the total harmonic distortion of the grid-connected current.On the other hand,using the error adjustment principle,the PI control made grid-connected current track the presetting sinusoidal reference signal in real time.Furthermore,a prejudged algorithm was adapted in the control strategy to eliminate the delayed influence due to inverter output filter as well as to make the phases of output current and grid voltage tend to the same.The experimental results show that the new control strategy has obviously improved the grid-connected current waveform and makes the frequencies and phases between the grid-connected current and grid voltage be completely in-phase.