Photovoltaic MPPT algorithm based on hysteresis comparison and optimal gradient

The power energy of photovoltaic cells changes according to the external environment. In order to get high-efficient photovoltaic array power, it is necessary for the photovoltaic grid-connected system to conduct maximum power point tracking system. This paper came up with a perturbation and observation method based on hysteresis comparison and optimal gradient method to overcome the problems of oscillation and erroneous judgement. To test the effectiveness of the new algorithm, a three-phase single-stage photovoltaic system based on the PSCAD/EMTDC software was built. On the basis, a comparable analysis was provided for the regular perturbation and observation method with fixed step and the improved one respectively. Simulation results show that the improved MPPT algorithm can effectively eliminate the ripples of DC side voltage caused by the disturbance; when there is a mutation of the external environment, the grid system can stabilize quickly at a new maximum power point.