基于MVPI的三相光伏并网逆变器控制方法

CONTROL METHOD FOR THREE-PHASE GRID-CONNECTED PHOTOVOLTAIC INVERTER BASED ON MVPI

提出一种新型控制策略,电流内环采用静止坐标系下的多矢量比例积分控制,消除特定次谐波、改善稳态性能,电压外环采用直流母线电压平方反馈以提高动态性能。搭建10 k W三相光伏并网发电系统样机平台,并对提出的控制方法进行实验分析,实验结果验证了该方法可有效减小光伏并网逆变器输出电流谐波,改善电能质量,提高系统运行的稳定性。

The traditional control method of the PV inverter which is used to regulate output current and generate trigger pulses is based on voltage-current double-loop control. For the unbalance of switching devices and poor working condition, the output currents always have large total harmonic distortion （THD） , which decreases the static performance. Besides, dynamic performance and static error are deteriorated because of the constant proportional and integral coefficients as well as integrator saturation. A new control strategy was proposed. The muhi-proportional-integral controller in stationary frame was adopted to eliminate specific harmonic for the inner current loop and enhance the steady property; the feedback of DC-link voltage＇ s square was used for voltage outer loop to improve the dynamic property. A prototype of 10 kW three-phase PV grid-connected generation system was established to analyze the proposed control method, the experiment results verify that not only the proposed method can decrease the harmonic of the output current of the grid-connected PV inverter and improve the current quality, but also enhance operation stability of the system.