Novel Global Maximum Power Point Tracking Algorithm for PV Array under Partially Shaded Conditions

Under partially shaded conditions, the P-U characteristic of the photovoltaic (PV) array is characterized by multiple peaks. The presence of multiple peaks reduces the effectiveness of the existing maximum power point tracking (MPPT) schemes, which refers only to the tracking of a single peak on the P-U characteristic. This paper proposes a novel method for the global MPPT. The new method starts at the starting voltage which is 80% of the open-circuit voltage of the PV array, and finds the first local maximum power point (MPP) using the perturb and observe (P&O) approach. Then the second search finds the next local MPP based on the P&O approach starting from the new starting voltage, which is determined by increasing the rate of slope of the current line at the first local MPP. The new algorithm follows this searching procedure until the global MPP is found. The new algorithm avoids searching the turning-point voltage between the two local MPP, and the voltage range swept is shortened significantly with the result of fast searching speed. Simulations validates that under partially shaded conditions the proposed new algorithm can track the global MPP with the fast tracking speed and the high precision.