Study Of Modeling And Simulation For Photovoltaic Fuel Cell Hybrid Generation System

Governments around the world have intensified for new energy development and utilizationto deal with the exhaustion of the fossil energy and the increasingly prominent environmentproblem. They hope to replace the traditional nonrenewable fossil energy by new energy andrealize the energy recycling. Compare with the traditional energy, solar energy as a renewableenergy has the advantages of rich and clean. China has abundant solar energy resources. Morethan 96% of the Chinese area’s total solar radiation is greater than 1050 kWh/m2per year.Consequently, photovoltaic fuel cell hybrid generation system is a good option to solve theproblem of no power or lack of power in some area of west China.Because the solar energy is random and intermittent, it can be affected by the weather, time,seasonal and other uncertainties. Thus, in order to obtain the continuous electricity supply, theindependent photovoltaic generation system must adopt necessary energy storage devices. Thequality of the energy storage device will directly affect the stability and reliability of the system.Fuel cell is generation equipment which directly converts the chemical energy non-combustion toelectrical power. In this process, outputs are mainly water and waste heat which have littleenvironmental pollution. Hydrogen is also an ideal non-polluting, renewable energy and can bestored for a long time thus can provide regulatory role for the seasonal fluctuations solar energy.Therefore, the water electrolysis cell is used to store a large number of hydrogen, or to providefuel for the fuel cells. This approach provides a new energy storage method for the photovoltaicgeneration system. However, compared with traditional energy storage battery, the energy storageconversion efficiency is lower. Micro turbine is a new distributed power developed in recent yearswhich attracts much attention for the advantages of its low environmental pollution, energyefficiency and more fuel selections. It can be used with fuel cells together to form a CCHP system,which provides new choice for photovoltaic hybrid generation system architecture.A photovoltaic fuel cell hybrid power generation system is proposed in this thesis, whichuses hydrogen energy to realize the continuous and stable energy storage, and output thecontinuous and stable power supply through interaction between the micro turbine and protonexchange membrane fuel cells. The mainly component of this hybrid system includesphotovoltaic array, proton exchange membrane fuel cell, proton exchange membrane electrolyzewater, micro turbine, electrical double layer capacitor, hydrogen tank, power transformationdevices and so on. In this study, the models of the key components are developed to construct thehybrid system simulation platform. Based on the design principle and requirements of photovoltaic generation system, this study designs a suitable capacity for the hybrid system. Andthen, the system energy management is studied according to the operation demands. The maincontributions of this thesis are as follows:(1) A simple capacity matching is designed for photovoltaic fuel cell hybrid generation systemaccording to its design principle, design basis and design requirements.(2) A hybrid photovoltaic generation system model is developed. This study delves into theWorking Mechanisms of the components in the hybrid system. The units are modeled with themodularization method in the Matlab/simulink environment, including PV arrays, fuel cells,electrolyzes, electrical double layer capacitor, micro turbine, power converters and so on. Thecharacteristic of each unit model is analyzed too. In addition, individual power generation systemcomprised of each distributed generation and power electronic components is simulated andanalyzed.(3) The maximum power point tracing (MPPT) controller of the PV arrays is analyzed, and theMPPT algorithm based on perturb & observe algorithm and incremental conductance is realizedin Matlab/simulink. And then, the quality of these two kinds of MPPT algorithm is compared andanalyzed.(4) The energy management of photovoltaic fuel cell hybrid generation system is studied. Aenergy management strategy based on time domain hierarchy is addressed. There are three energymanagement levels according to the proposed energy management strategy: 1) advance energymanagement based on photovoltaic prediction and loads forecasting; 2) the energy managementbased on mode of operation switch; 3) real-time energy management based on the power trackingcontrol. Finally, the real-time energy management based on the power track control is simulatedand analyzed in the environment of Matlab/simulink.