The Research Of A CHP System Based On PV-PEMFC-Battery

With the rapid development of economic construction,the demand for coal and fossil fuels is rapidly growing,and in recent years,our country continue to appear serious haze weather which has badly impact on people's health,so looking for the development of new clean renewable energy is an urgent action.The utilization of the combined heat and power(CHP)system based on new energy is a effective solution to improve energy utilization,especially the CHP system for the home users,which can reduce the pressure of large power grids,but also it's flexible and controllable,there is a lot of room for development.Fuel cell has many advantages such as the high energy utilization rate,small volume,low noise,other more,it produces no pollutants at all so is often used in a CHP system.The battery has the advantages of high energy density,but the volume is large,and it has a certain degree of self discharge,which is not suitable for long time storage.In this paper,proton exchange membrane fuel cells(PEMFC),photo-voltaic and battery are chosen to make up the CHP system for home user.At present,most of the research on the system has not been combined with the actual PV output and household electric load to carry out capacity planning,and the system's operation model has not been analysis in detail.In this paper,further research has been done on the above problems.Firstly,the MATLAB/Simulink model of the distributed generation is built according to the mathematical model,and the output characteristics of the model are analyzed in different conditions.For fuel cell and hydrogen storage tank,the thermolib model is used to analyze the thermal efficiency and the optimal hydrogen gas flow rate of the fuel cell under different control current.Secondly,according to the typical electric and heat load curve,combined with Hangzhou local photo-voltaic average daily output curve,and take the initial cost,replacement cost and operational cost of the each part of the system into account,the optimized capacity of the PV,battery,fuel cell,electrolytic cell,hydrogen tank and the converter was given in the Homer software.On the optimum ratio,the system can produce the power of 484640 kwh and heat of 107960 kwh in the 20 years life time,it can roughly meet the domestic demand for electricity and half of the heat demand.At last,the integrated model of the CHP system is built based on the preamble,the battery charge or discharge process and the temperature control system of the fuel cell are also established.The simulation results show that the temperature of the fuel cell stack can be effectively controlled by controlling the cooling water flow rate.The overall operation of the system was simulated,and the operating mode of the system was simulated under different light intensities.The simulation curves include light intensity,the photo-voltaic output,the storage state of the battery,the output curve of the fuel cell and the DC bus voltage.From the DC bus voltage curve we can see that the system can be stable operate when switching between different modes.