Energy Management System Research For Domestic Grid-connected/Stand-alone Integrated Photovoltaic Power System

Renewable energy distributed generation plays a key role to maintain dynamic and sustainabledevelopment for every government. Solar photovoltaic power has become an attractive energy supplyoption as a result of fossil fuel depletion and environment pollution. This paper puts forward an efficientenergy management strategy for domestic grid-connected/stand-alone integrated photovoltaic powersystem to ensure the stability of the system operation.The domestic grid-connected/stand-alone integrated photovoltaic power system is composed bysolar cells、lithium battery、public grid、local loads and power converters. The power converters consistof boost converter in PV side，buck-boost converter in battery side and full-bridge converter in load side.All these converters connect to the DC bus composing a DC micro-grid. They work individually at thecommand of system’s energy management module to control the voltage of DC bus to a constant value.The domestic photovoltaic power system can work on four different operation modes:1) stand-alonewith PV power generation;2) grid-connected inversion;3) stand-alone with battery power supplying;4)grid-connected rectification. The paper analyses each converter’s control strategy when the system workson different operation mode.The paper defines the priority of power supply among the three micro sources in the system, whichranks PV as first, then battery and grid last. Based on the principle of power supply priority, the paperproposes an energy management strategy for the system. The strategy can ensure the stability of thesystem by changing the work patterns of three inverters according to the variation of photovoltaic outputpower, battery’s SOC and load conditions. The simulation results which model in Matlab/Simulationsuggest that the energy management strategy can switch the operation mode of the system reasonably,so as to realize the stable operation of the system.Then the paper designs the hardware circuit and software process of the system’s energymanagement module block. Experimental results on a5kW domestic grid-connected/stand-aloneintegrated photovoltaic power system prototype verify the validity of the proposed energy managementstrategy. The domestic power system can work steady and provide continuous power for the load.