Optimization Design Method for Photovoltaic and Energy Storage Grid-Connected Microgrid Considering Power Optimization of Distribution Network

Abstract

Microgrid is a novel power grid that combines various distributed generation, energy storage systems, and loads. It complements the distribution network to realize energy saving and emission reduction. To optimize the power of the microgrid that is connected to the distribution network and maximize the utilization rate of renewable energy, this study proposed a design method, a work mode, and a control strategy for photovoltaic (PV) and energy storage microgrid. A PV and energy storage microgrid structure was designed on the basis of the organic whole of a grid-connected microgrid and distribution network. According to the maximum and minimum load operations of the system, a mathematical model for determining micro-power capacity was established. Moreover, a mathematical model of coordinated control of microgrid system was established by controlling the active and reactive microgrid power separately. The membership function of control variables was proposed, and the fuzzy set of control variables and the fuzzy control decision table were established to determine the working mode of active micro-source. Taking the actual typical daily load characteristic curves in summer and winter as examples, the effectiveness and superiority of the proposed optimization design method for microgrid were verified. Results demonstrate that the work mode and control strategy of the microgrid system cannot only smoothen the active power at the head end of 0.4 kV distribution line but also optimize the reactive power of the system. The power factor of 0.4 kV distribution line meets the requirements. The study can be used as reference for designing a microgrid that is connected to the distribution network.