Research On MPPT Control Of Photovoltaic Array Under Partial Shaded Condition

The excessive exploitation of fossil fuels brings about resources depletion and tremendous pollution.To solve this problem,the development and utilization of renewable energy vigorously instead of fossil fuels have been hot topics in the 21st century.Solar energy has obtained a rapid advancement for its advantages of wide distribution?huge storage and non-pollution.Photovoltaic generation is a important approach to utilize solar energy,so researching the key technologies of photovoltaic generation have always been the research priorities for relevant experts at home and abroad.The photovoltaic array's output power curve has more than one peak power points under partial shaded condition.This thesis conducts a relevant study,and proposes a MPPT control algorithm for partial shaded condition.The main works of this thesis are as follows:1?Making the detailed analysis of photovoltaic cell's mathematical models and output characteristics.To verify the previous theoretical derivation,a simulation model based on photovoltaic cell's mathematical models in engineering has been established by Matlab/Simulink.2?Partial shading results in photovoltaic array's power mismatch and the hot spot effect.To solve the problems,paralleling bypass diodes and cascading blocking diodes is the common solutions,however these diodes bring about more than one peak power points for the photovoltaic array's output power.By buiding the simple series-parallel photovoltaic array's mathematical models,the two kinds of photovoltaic array'soutput characteristic equation has been deduced,and a simulation model of the photovoltaic array's under partial condition is eatablished by Matlab/Simulink.3?In a photovoltaic generation system,the DC/DC converter is used for a MPPT controller besides changing the voltages.Through analyzing and comparing the Boost converter and the enhanced Luo-converter detailly,it's obvious that the enhanced Luo-converter has higher voltage gain and lower output voltage ripple.Simulation experiment's results also demonstrate above conclusion well.4?Firstly,making the detailed analysis of 3 traditional MPPT control algorithms'principle which are applied to uniform illumination condition,and proposing a modified variable step size P&Q algorithm.Using the 4 control algorithms to carry out simulation experiments based on the MPPT control simulation model adopting the enhanced Luo-converter by Matlab/Simulink.Then,giving a introduction of MPPT control algorithms' research under partial condition at present.At last,proposing a probability theory thinking's globle MPPT control algorithm.The algorithm make use of probability theory thinking to seek a small area that include the global MPP,and then in the small area accurate tracking the global MPP using the modified variable step size P&Q algorithm before.At the same time,carrying out the simulation experiments based on the MPPT control model of the Boost converter.Comparing the two different DC/DC converters' output voltage ripple,and the simulation results greatly support the advantages of the enhanced Luo-converter.5?According to the analysis of overall structure and control circuit based on DSP for the photovoltaic system's experimental platform,the platform's software and hardware design are accomplished.