A novel smooth switching control strategy for multiple photovoltaic converters in DC microgrids

• Published in: Journal of power electronics Vol. 22; no. 2; pp. 163 - 175
• Main Authors: Zhang, Qinjin, Hu, Wangbao, Liu, Yancheng, Zhang, Hanwen, Wang, Honglai
• Format: Journal Article
• Language: Korean
• Published: 2022
• Subjects: dp/di control; Multiple PV converters; DC microgrid; Mode smooth switching
• ISSN: 1598-2092; 2093-4718

With the photovoltaic (PV) penetration rate increasing in PV-storage-based DC microgrids, the conventional PV controller with only the maximum power point tracking (MPPT) control function can hardly meet the needs of the coordinated operation. The PV converter should operate at the MPPT or the constant voltage droop (CVD) mode according to the load demand. Two sets of relatively independent control loops are used to control the two modes. Inevitably, bus voltage and PV output power fluctuations are caused in the process of mode switching. This paper proposes a novel smooth switching control strategy for the smooth transition of multiple PV converters between MPPT and CVD modes. When combined with the PV array output characteristic curve, the value of dp/di is selected as the control variable. By tracking different dp/di command values, the PV converter can realize the control of the MPPT mode, the CVD mode, and smooth switching between the two modes. The MPPT and CVD modes are unified in the sense of using the same control loop, which avoids control loop switching during the PV mode switching. Finally, the effectiveness of the novel smooth switching control strategy is verified by the simulation and hardware in loop (HIL) experimental tests.