一种单相光伏并网逆变器改进预测电流控制算法

An Improved Predictive Current Control Method of Single-Phase Photovoltaic Grid-Connected Inverter

光伏并网逆变器传统预测电流控制算法由于采样与计算延时会造成差一拍控制,使得逆变器并网电流不能很好地跟踪目标电流,同时逆变器滤波电感模型值与实际值有误差时会造成并网电流谐波大,还可能导致系统不稳定。为克服这些不足,提出了一种改进的预测电流控制方法,可提前一个采样周期对并网逆变器输出电压进行预测,同时利用递推最小二乘法对电感参数进行在线辩识。仿真和试验结果表明所提方法有效提高了逆变器并网电流对目标电流的跟踪精度,减小了并网电流的谐波分量,提高了由逆变器进网的电能的质量。

The traditional predictive current control algorithm of photovoltaic grid-connected inverter would cause the beat control due to the sampling and calculation delay,so the current which was sent to the grid could not track the target current well.Meanwhile,the error between the model and the actual value of the inverter filter inductance would cause harmonic to grid current,and cause instability to inverter system.In order to overcome these shortcomings,an improved predictive current control method was proposed.In the improved predictive method,the output voltage of the grid-connected inverter was predicted in a previous sampling period,and recursive least square method was used to identify the inductance parameters online at the same time.Simulation and experimental results showed that the proposed method can effectively improve the tracking accuracy of the grid-connected current to the target current,the harmonic component of the current sent to the grid was reduced.The quality of power supported by the inverter was improved.