电力电子技术

电网电压发生不平衡故障时,大功率并网逆变器有效的调节控制可以提高其并网运行的能力。主要研究在α,β坐标系中三相并网逆变器的模型预测控制(MPC)策略。在电网电压不平衡的故障下,大功率并网逆变器充分利用MPC在低开关频率条件下的高动态性能和稳定性能,直接对正负序电流进行控制,避免了电流的正负序分解,通过控制电网负序电流为零、抑制有功功率或无功功率二倍频脉动,以满足电网电压不平衡时逆变器的并网电流要求。在一台2 kW的L型并网逆变器实验平台上进行了实验验证,依次实现了3种控制目标。实验结果表明了该方法的有效性及正确性。

The effective control of high power grid-connected inverter under unbalanced grid voltage condition is able to enhance the grid-connected operation ability of the inverter.The control scheme of a three-phase grid-connected inverter with model predictive control(MPC) on the a,/3 reference frame is studied.In the case of unbalanced grid voltage,the high dynamic performance and stability of the high power grid-connected inverter under low switching frequency is fully taken advantage of to control both positive and negative current component directly without any decomposition and grid-connected current requirements are satisfied by controlling negative sequence current of the grid to zero, suppressing active or reactive power second pulsations.Three control targets are respectively achieved on the experimental platform of a L grid-connected inverter, whose capacity is 2 kW. Experimental results demonstrate the effectiveness and correctness of the method.