Control Scheme of Distributed PV Plants in Partial Shading Conditions for Improved Transient Stability

Nearly, distributed maximum power point tracking (DMPPT) technologies based on the DC optimizer (DCO) for each single PV panel, have been widely concerned to mitigate the solar energy loss of photovoltaic (PV) power plants caused by the array mismatch problem under partial shading conditions. However, when the partial shading conditions become severe, the transient stability of the distributed PV generation system will be weakened due to the power imbalance between the PV modules. To solve this problem, a new control scheme for the DCO-based distributed PV plants is proposed to improve the system transient stability when a large disturbance occurs. First, the dynamic response of the Buck-DCO-based PV system under serious mismatch is analyzed. The improved control scheme is then established to deal with the saturation problem of integrators in control systems based on the former dynamic characteristics analysis. Finally, simulation results show the effectiveness of the proposed control scheme.