A coordinated control strategy is proposed for smoothing power fluctuation of grid-connected photovoltaic (PV) plant

including the operating point control of maximum power point tracking (MPPT) of PV’s and charging／discharging power control of hybrid energy storage system (HESS). The proposed strategy could effectively smooth PV power fluctuations within the acceptable range of the utility grid with the close cooperation between PV and HESS. Multi-objective nonlinear constraint model is adopted to optimize the charging／discharging power of the battery and supercapacitor. During the dispatching process

the lifetime of HESS

state of charge (SOC) deviation of HESS and the discharge efficiency are fully considered. Moreover

the moving average algorithm is utilized to dynamically control the operation point of the MPPT of PV. Besides

three typical scenarios of PV power fluctuations are established by using K-means clustering algorithm. Also

several comparisons are made between the proposed strategy and the conventional strategy which also uses HESS to smooth power fluctuations. Simulation results demonstrate that the proposed approach could not only achieve a significant effect of smoothing the PV power fluctuations

but also reduce the operation loss of HESS and prolong the lifetime of HESS.