Design and implementation of a hybrid maximum power point tracker in solar power system under partially shaded conditions

摘要

In this paper, a novel hybrid maximum power point tracking (MPPT) method under partially shaded conditions (PSC) is proposed. The duty cycle of the dc-dc converter is controlled from small to large with fixed intervals in order to scan the P-V characteristics curve under partially shaded conditions, and then find out the maximum power value, which is called duty sweep (DS) algorithm in this thesis. With the proposed control algorithm, as soon as the DS process is finished, the perturbation and observation (P&O) method immediately starts so as to track the real MPP under PSC. In addition, the value of perturbation can be set as small as possible in order to achieve high tracking accuracy and decrease the oscillation phenomenon causing by conventional P&Q method because the tracked point after using DS process is very close to the real MPP. The digital signal processor (DSP) TMS320F2812 from TI is used to implement the proposed control method in a Boost converter which is utilized to act as the power converter topology. Finally, experimental results confirm the proposed maximum power point tracking method that can accurately and promptly track the real MPP of PV arrays even under PSC, overcoming unpredictable weather conditions and rising up the utilization of PV arrays. In addition, compared to the conventional P&O MPPT method, the experimental results also shows it is speedier to find the real MPP using the proposed hybrid algorithm even there is no any PSC occurs.