牛春豪,徐永海,范兴管.电网不平衡下级联型电力电子变压器的网侧谐波抑制方法研究*[J].电测与仪表,2024,61(9):40-47. NIU Chunhao,XU Yonghai,FAN Xingguan.Research on grid side harmonic suppression method for cascaded power electronic transformers under unbalanced grid conditions[J].Electrical Measurement & Instrumentation,2024,61(9):40-47.
电网不平衡下级联型电力电子变压器的网侧谐波抑制方法研究*
Research on grid side harmonic suppression method for cascaded power electronic transformers under unbalanced grid conditions
Cascaded H-bridge converter is widely used in medium voltage applications, especially in the input stage of power electronic transformer, because of its cascade structure. However, under unbalanced grid conditions, the power fluctuation on AC side will cause the voltage ripple on DC side to increase abruptly, resulting in the current distortion on grid side. Aiming at this problem, a harmonic suppression method for cascaded power electronic transformers under unbalanced conditions is proposed in this paper. The generation mechanism of grid side harmonics is deduced and analyzed, and the coupling mechanism of AC side harmonics and DC side ripple is revealed; Based on this mechanism, an improved quasi-proportional resonant controller is proposed to suppress the grid side harmonics, and the stability of the control system is analyzed; A simulation model is built in PSCAD/EMTDC, and compared with the traditional control strategy, the effectiveness of the proposed harmonic suppression strategy is verified.
