不平衡电网下并网逆变器功率模型预测控制

当电网电压不平衡时,并网逆变器侧有功/无功功率波动、并网电流谐波显著增加。为解决该问题,提出一种新型的模型预测功率直接控制策略MPDPC(model predictive direct power control)。在该控制策略中,采用电网电流、电网电压及其1/4周期延迟信号和电容电压差搭建功率模型;然后选择功率模型预测控制中最优的开关状态,有效地消除了逆变器输出有功功率2倍频脉动,电流谐波,实现给定有功功率和无功功率的精确跟踪。仿真和实验结果表明,该方法能消除电流谐波,实现三相电流基本平衡。

Power Model Predictive Control of Grid-connected Inverter Under Unbalanced Grid

Under unbalanced grid voltage,the active/reactive power fluctuations and grid-connected current harmonics with a grid-connected inverter will increase significantly.To solve this problem,a novel model predictive direct power control(MPDPC)strategy is proposed,in which a power model is constructed by using the grid current,grid voltage together with its signal of 90gndelay,and the difference in capacitor voltage.Afterwards,the optimal switching state under MPDPC is selected to effectively eliminate the double-frequency pulsation in the active power output from the inverter as well as current harmonics,thus realizing the accurate tracking of the given active power and reactive power.Simulation and experimental results show that the proposed method can eliminate current harmonics and realize a basic balance of three-phase current.