Double-layer Capacity Configuration Method of Hybrid Energy Storage in Microgrid Considering Three States of Wind Turbines and Photovoltaic Units

In view of the fact that during the energy storage configuration in traditional microgrid the multi-state operation of wind power generating units and photovoltaic (abbr. PV) generating units are seldom considered, so its configuration model does not possess universality. For this reason, a bi-layer planning method for hybrid energy storage configuration of improved microgrid, in which the three states of wind and PV were considered, was proposed, meanwhile the introduction coefficient and the on-off grid coefficient were put forward to flexibly perform the selection and combination of different types of micro energy sources and their grid-connection and off-grid to make its applicability more extensive. In the capacity constraints of the upper layer model a set of initial capacity values of wind power and PV power were randomly selected to build the tri-state model of wind power units and PV power units, and according to the initial capacities of wind power and PV power imported in the upper layer model the output of the lower layer model was calculated meanwhile the reliability was taken into account and a configuration model, in which the minimum total cost of the microgrid was taken as the objective, was constructed. The Fourier transform was utilized to conduct spectral analysis on the power shortfall in one cycle to determine the output of the hybrid energy storage and that of the tie-line, and to transmit the results to the upper layer, then the adaptive genetic algorithm was used to obtain the optimal solution of wind power and PV power by the iteration and to work out the optimal configuration result of hybrid energy storage. Finally, a certain practical microgrid system was adopted to perform the analysis on example. The results of the analysis on example show that the constructed model can apply to both microgrid islanding mode and grid-connected operation mode.