The Micro-grid Optimization Based On Distributed Generation

Coal-fired power plants account for more than 60% of the total power generation of the energy construction of China.In China,energy consumption is mainly depends on coal-fired plants,which is the main reason for environmental pollution and greenhouse-gas.In order to ease environmental and green-house-gas problem,more and more researchers begin to focus on the renewable energy.As a kind of new energy,solar energy has many advantages such as pure,renewable,abundant etc.Furthermore,compared with other renewable energies,solar energy is the most abundant and inexhaustible.To promote the development of solar energy,several policies were proposed by Chinese government,such as the plan of solar roof of buildings.It’s necessary to evaluate economic benefits in the PV industry.The s net present value(NPV)and payback time(Pd)are used to determine profitability.In its life cycle,production,installation,transportation,and system disposal or recycling of PV modules and balance of system(BOS)require much energy.Lifecycle assessment(LCA)is perfect to evaluate the sustainability of PV system.Energy payback time(EPBT)and Greenhouse-gas payback time(GPBT)are institute ways to evaluate environment benefit.PVSOL software is used to investigate economic and environmental benefits of PV systems with different installation powers,load profiles,capacities of batteries,and incline angle of PV modules.The economic,environmental benefits and performance of two PV systems are illustrated and details are as follows:(1)The first chapter introduces the concept of micro-grid and the development status,the current development of photovoltaic industry and economic,environmental benefits of PV systems.Nowadays study on economical efficiency mainly focus on the former higher cost period,and the subside mainly considered investment subside,electricity output subside is less considered(2)The second chapter introduces photovoltaic system,output characteristics,mathematical model of photovoltaic cell,output characteristics under different temperature and irradiance,photovoltaic maximum power point tracking system,as well as battery model and mathematical model of load.With the increament of voltage of PV modules,the electricity output rise gradually and drop sharply after reached the highest point.With the increament of illumination intensity,the maximum power increases,and with the increament of temperature,the maximum power decreases.(3)The third chapter mainly studies PVSOL software data selection,Energy distribution performance of PV systems with different angle,different instillation power,different load profiles,and PV systems under different battery capacity.The chapter also studies self-sufficiency rate of system performance with or without battery system changes.When the tilt angles are around 23o,the output power of PV modules reach highest.The self-sufficiency rate of PV systems with industrial load is higher than commercial load,and the self-sufficiency rate of PV systems with residential load is the lowest.The self sufficiency rate of PV systems with batteries are higher than PV systems without batteries,and the increament of installation power can increase self-sufficiency rate of the PV system.(4)The fourth chapter mainly studies the formula and parameters of economic benefits evaluation of PV systems with different angle,installation power,load profiles,even load with extreme characterload of system.The chapter also studies economic performance of micro-grid with connected residential and commercial load profiles,and economic influence of cleaning photovoltaic panels.The best installation tilt angles are 23o、24o.With the increasement of installation power,the cost of each installation power decreases.A certain load profile and power correspond with an fixed best installation power.When combined with PV systems under the same installation power,the economic benefits of industrial load PV system and commercial load PV system are higher than residential load PV system.The mixture of different load profiles can improve system economic benefits.The cleaning cost of PV systems is high,without which the output of PV system will decrease,and earnings will drop highly.(5)The fifth chapter mainly studies the formula of environment benefits of PV systems.EPBT,GPBT,the pollutants of environmental value,and other environmental benefits are analyzed.The bottom part studies weather type classification and weather forecast program.For a 6kW PV system,the EPBT is 3.88 years and GPBT is 4.03 years.The occupation rate of land is 54.96%.When predict the weather with patter recognition method,the accuracy rate can reach to 70%.(6)Chapter six introduces performance,economical and environmental benefits of two actual PV systems.The payback period of 3kW PV system are between 12.4 to 14.4 years,the payback period of 10 kW PV system are between 10.9 to 11.6 years.The overall environmental benefit of 3kW PV system is 26963.47￥,and the overall environmental benefit of 10 kW PV system is 99352.42￥.(7)Chapter 7 is the summary of the above content and perspective according to the present research are prospected.Differnet land types,PM2.5,different kinds of batteries,and frequency of cleaning can be considered in further research.