为提高三相并网逆变器的功率等级,提出一种由耦合电抗器组成的新型并联型三相并网逆变器,通过对耦合电抗器去耦得出并联型逆变器的等效电路,并分别在三相静止坐标系和同步旋转坐标系下建立平均模型,阐明耦合电抗器抑制零序环流的根本机理,即耦合电抗器可以增大零序环流阻抗.根据所得平均模型设计电流解耦控制策略,抑制了零序环流,解决了零序环流引起的不均流、波形畸变问题,提高了系统的可靠性和效率.最后,对一组1.5 MW并联型三相并网逆变器进行了仿真验证,结果证明了上述分析及控制策略的正确性.%To increase the power rating of three-phase grid-connected inverters, a topology of parallel three-phase grid-connected inverters composed of interphase inductors is proposed. The equivalent circuit was derived by decoupling the interphase inductors. Besides, the average-value models were obtained in the three-phase stationary coordinates and the synchronous rotating coordinates respectively. The fundamental mechanism of zero-sequence circulating current suppression with interphase inductors is that the interphase inductors can increase the impedance of zero-sequence circulating current. Then the control strategy of the system was designed according to the average-value model in the synchronous rotating coordinates. The zero-sequence circulating currents were suppressed well and the discrepancy and distortion of currents were overcome. Therefore, the reliability and efficiency of the system were improved. Finally, the parallel three-phase grid-connected inverters with the power rating of 1. 5 MW were simulated, which verified the validity of the above analysis and control strategy.
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