Research On Energy Management Of Independent DC Micro Grid Based On Photovoltaics/Fuel Cell/Battery System

With the rapid penetration of economic globalization,the world’s increasingly scarce energy and increasingly prominent environmental pollution problem has become an important issue that cannot be ignored.At present,China has incorporated renewable energy into an important part of the national energy structure.The micro-grid technology can penetrate into the distribution network better with the distributed power supply represented by solar energy,wind energy and biomass.The effect of intermittent distribution on distribution network is reduced and the distributed power supply is fully utilized.Among them,dc micro grid is the support and supplement of ac distribution network,which can play plug and play,fast and reliable,etc.,to effectively solve the existing problems of distribution network,which is of great significance.This paper builds an independent dc micro grid based on the light burning storage system.According to the performance characteristics of the distributed power photovoltaic cells and fuel cells,different control methods are studied to optimize the micro power supply.According to the topology and operation requirements of independent dc micro grid,an energy management strategy based on finite state machine theory for dc micro grid is designed and verified by simulation.According to the research of light fuel storage system of the independent dc micro grid topology,selected by photovoltaic cells output as a micro power grid main output energy,storage battery and proton exchange membrane fuel cell(PEMFC)as auxiliary power.For the use of photovoltaic cells to achieve maximum efficiency,this paper studied a kind of search algorithm based on improved backtracking photovoltaic maximum power point tracking(MPPT)method,effect is better,to make pv MPPT tracking photovoltaic output is more smooth and steady.In order to solve the problem that the dynamic characteristic of fuel cell is slow,the output power frequency fluctuation will affect the life and performance of the power reactor.In this paper,a kind of fuel cell output optimization control based on VDG is studied.The control fuel cell side DC/DC converter output shows the dynamical characteristics of the DC generator to improve the inertia and damping of the fuel cell power system and enhance the stability of the system.According to the performance parameters of each module of the system,the simulation model of photovoltaic cell,fuel cell,battery,DC/DC converter and the whole system is built in Matlab/Simulink software.An energy management strategy based on finite state machine theory is designed for the independent dc micro grid system.According to the battery SOC system work pattern of high,medium and low mode is divided into three level,which in turn according to the demand for power,photovoltaic battery power output,fuel cell output power,output power battery four numerical relationship is divided into 10 sub model,energy management and control,respectively.Using established the simulation model for the energy management strategy is analyzed,designed and aimed at high SOC model,model of SOC,low SOC in the three modes of system working condition are simulated respectively.Results show that the design of finite state machine energy management strategy can effectively adjust the battery SOC gradually achieve a reasonable scope,the demand for each micro dc micro power grid power supply power to realize the reasonable allocation.