LCL滤波并网逆变器的进网电流相位矫正技术

文中分析了LCL滤波并网逆变器系统的稳定性。该并网逆变器采用逆变器侧电感电流作为反馈量,并采用电网电压前馈控制策略,由劳斯判据得到该系统恒稳定的结论。由闭环系统的传递函数确定了电压前馈系数的大小,并根据闭环系统的根轨迹设计了电流环的控制参数。分析了该闭环系统并网功率因数小于1的原因,为克服这一缺点,提出了进网电流相位矫正技术。该技术根据进网电流与电网电压之间的相位差调节电流环基准值的频率,最终使进网电流与电网电压同相位,并网功率因数等于1。进网电流相位矫正技术不会影响原有系统的稳定性。仿真结果验证了该策略的有效性。

A Phase Correction Technique for Grid Side Current of Grid-connected Inverter with LCL Filter

According to the Routh criteria,a grid-connected inverter with a LCL filter is stable when the output current of the inverter is used as a feedback variable.The feed-forward coefficient of the grid voltage is obtained from the transfer function of the closed-loop system.The control parameters of the current-loop are designed according to the root locus.The power factor of the grid-connected inverter is not unity.To overcome this shortcoming,this paper proposes a phase correction technique for the grid side current of the inverter.The technique adjusts the frequency of reference current according to the phase separation between the grid voltage and the grid current.The proposed technique improves the power factor to unity.In addition,the technique hardly affects the stability of the closed-loop system.The simulation results verify that the performance of the proposed technique is excellent.