空间相位解析的三相并网逆变器不平衡控制策略

A Novel Control Strategy for Three-Phase Grid-Connected Inverter Based on Space Phase Analysis Under Unbalanced Input Voltage Condition

鉴于公共电网常处于三相电压不对称运行状态,本文提出一种基于电网电压矢量空间相位解析的并网逆变器不平衡控制新策略。该控制策略通过捕捉电网电压正、负序重合角解析电压和电流正、负序分量的空间相位关系,直接以不平衡的电网电压矢量进行定向并根据常规比例积分(PI)控制器设计了一种新颖比例离散积分控制器,实现对2倍工频的并网电流有功分量和无功分量的零稳态误差控制,且无需计算并网电流正、负序分量,降低了系统计算负荷。实验结果表明,该控制策略可显著抑制电网电压不平衡工况下脉宽调制(PWM)逆变器直流侧电压2次谐波和并网电流畸变。

Considering unsymmetrical input grid voltage, a novel control strategy for grid-connected inverter based on space phase analysis under unbalanced input voltage condition is developed. This control strategy captures coincidence angle to analyze space phase relationship between positive and negative sequence components of grid voltage. And a proportional discrete integrator controller is designed based on conventional proportional proportional integral （PI） controller which can achieve zero steady-state error control for double power frequency active power and reactive power grid currents. Extraction of positive and negative sequence components of current is not needed any more and the amount calculation is reduced greatly. Experimental results indicate that the control system can eliminate the second harmonic waves of DC voltage and distortion of line currents under unbalanced input grid voltage condition.