MPPT Technology In The Photovoltaic Power Generation System

The energy issue has been the focus of public concern. The finiteness of the fossilfuels which take pollutant into the air makes people to look into renewable energy. Solarenergy is one of renewable energy. One advantage is clean and free from contamination.And the total can be described as inexhaustible. The importance attached by the peopleof photovoltaic power generation is constantly growing, as it is an effective way tosolve the energy problem. But the conversion efficiency of the current photovoltaic cellsin expensive price is low which make increasing its power generation efficiency to benecessary. The study of the maximum power point tracking (MPPT) is important anddeveloping very quickly all these years.Firstly, the basic principles of photovoltaic power generation is introduced in thispaper. And the major component of the photovoltaic power generation is analysised indetail.Theory and equivalent circuit and mathematical model of the photovoltaic cells isintroduced, as well as the variety and type of battery and its charge and dischargecontrol, controller, the classification knowledge and its control method of the inverter.There is three kinds of detection methods to solve the harm of Island effect. The basicmaximum power point tracking method: the constant voltage method, perturbationmethod, and the conductance increment method have been painstakingly introduced.The advantages and disadvantages are mentioned.Secondly, the comparative analysis of several control maximum power pointtracking DC/DC converter circuit is described. The principles and the choice ofparameters of three circuits which is Buck、Boost、Buck-Boost circuits. It choices theDC/DC appropriately as a front-end circuit to control the duty cycle which canmodulate of the output of the photovoltaic array in order to achieve the MPPT.Thirdly, detailed analysis of the various improvements of the variable step sizemethod, neural network, fuzzy control method has been done. The steps of thecalculation method based on unconstrained optimization effectively improve thetracking speed and accuracy to achieve the MPPT. It introduces the model and thelearning algorithm of the neural network method, and the advantages of BP neuralnetwork. The idea, development, and controller design steps of fuzzy control and thethree ways of defuzzification have been mentioned.Finally, analysis the problems of the above methods and improvement ideas andverify the feasibility of the related theory have been analysised.The final summary has analysised the full text and the future development ofrelated technologies and the next step of study and research to make the prospect.