A fast maximum power point tracking method for photovoltaic arrays under partially shaded conditions

Abstract

Aiming at the multiple peaks phenomenon on the power-voltage characteristic curve of photovoltaic (PV) array under partially shaded conditions, this paper proposes a fast global maximum power point tracking method based on sliding mode control (SMC). First, according to the operating characteristics of PV arrays, a reduced scanning range is adopted to avoid large power fluctuations and the optimal scanning direction of global maximum power point (GMPP) is determined to avoid the repeating scanning of the PV curve, both of which reduce the scanning time greatly. Second, during the scanning and tracking process, SMC is introduced to move the operating point quickly to the reference value, which improves the scanning speed further. Finally, when the operating point is close to the GMPP, the control mode is switched from the SMC based tracking control to the SMC based maximum power point tracking control, which quickly stabilizes the operating point of the PV array at the GMPP, reducing the power ripple during steady-state operation. Furthermore, the proposed method is independent of PV parameters, due to the new open circuit voltage detection method proposed in this paper, which does not occupy extra time. Simulation and experimental results validate that the proposed method can guarantee accurate convergence to the GMPP with fast tracking process and low energy loss under partially shaded conditions.

Maximum power point tracking scheme with partial shading detection for two‐stage grid‐connected photovoltaic inverters

“…Over the last decade, a large amount of researches have been reported to address the problem caused by partial shading (PS) effect by new MPPT approaches [9, 10]. These approaches mainly include three groups, namely modified conventional methods [11–14], soft computing based techniques [15–22], and PV array topology‐based techniques [23, 24]. The PV array topology‐based techniques arouse less interest than the other two.…”