不平衡电压下并网逆变器功率与电流协调控制

Coordinated Control of Power and Current of Grid-connected Inverter Under Unbalanced Voltage

当电网电压不平衡时,逆变器并网功率恒定与电流无谐波无法同时实现。首先分析了并网功率波动和电流谐波产生的机理,然后提出了一种功率与电流协调控制策略,在静止坐标系下,利用直接功率控制算法得到功率控制时的指令电流,采用级联低通滤波器滤除前述指令电流中的谐波分量得到电流控制时的指令电流,进一步地,通过加权思想实现功率与电流协调控制,无需锁相环和电压/电流正负序分量提取,算法简单。最后通过仿真和实验验证了所提控制策略的有效性。

The output power fluctuation and current quality of the grid-connected inverter under unbalanced voltage environment are opposite to each other.Firstly, the mechanism of current harmonics and power fluctuations is analyzed. Then a power and current coordinated control strategy is proposed.In the stationary coordinate system,the direct power control algorithm is used to obtain the command current in the power control.The cascade low pass filter is used to filter the harmonic components in the foregoing current to get command current of the current control.Further,the power and current coordinated control is realized by adjusting the command current through the weighting idea.This method does not require the phase-locked loop and the voltage/current positive and negative sequence component extraction, and the algorithm is simple.Finally, the effectiveness of the proposed control strategy is verified by simulation and experiment.