The Research Of Photovoltaic System And It's Maximum Power Tracking Algorithm

With the increasing depletion of fossil fuels, environmental pollution has become worse and worse, thus solar photo voltaic power generation is highly valued around the world. The maximum output power solar photo voltaic cell will change according to the change of temperature, sunlight intensity and other external parameters. PV array has the feature of nonlinear and time-varying, which can not establish a precise mathematical model. Hence Maximum Power Point Tracking (MPPT) technology which is to improve the utilization of solar energy of photo voltaic system has become a hot issue. The traditional way of conventional MPPT is very rather difficult to keep a good system with dynamic performance and steady performance. Fuzzy control is well applicable to non-linear case, but it is difficult to meet the requirements of high precision and good robustness, thus the paper presents a MPPT Fuzzy PID control strategy. The main works are as follows:Firstly, the paper analyzes the composition of photo voltaic and select independent power generation system to study. Then the paper analyzes the DC/DC converter topology of the maximum power point tracking, and select Boost converter circuit as the main circuit of the system and design its parameters.Secondly, the paper builds simulation models based on the equivalent circuit of the photo voltaic cell and analyzes the output characteristic curve. It also illustrates the principles of maximum power point tracking profoundly from the system itself. Traditional MPPT methods include constant voltage, perturbation and observation method, three-point center of gravity comparison method, incremental conductance method, and make a full analysis of their principles and their advantages and disadvantages as well as the occasions to use. For the shortcomings of traditional control methods, in order to improve the tracking speed and the steady state performance, this paper presents the formation of the policy on fuzzy PID control by combining a fuzzy control and PID control.Thirdly, the paper makes detailed illustration of fuzzy control and fuzzy PID control design. Taking Matlab/Simulink as a test platform to build a simulation model of MPPT PV systems, and make an application of perturbation and observation method, fuzzy control, fuzzy PID control method respectively to achieve the simulation of MPPT PV systems.The simulation results show that the fuzzy PID control method has a good dynamic performance and steady performance. The simulation results show that the fuzzy PID control method has a good dynamic performance and steady performance, which can track the maximum power point quickly when the environment changes suddenly. And it enables the PV system to remain at the maximum power output and eliminates the system output power near the maximum power point oscillation phenomenon, thereby enhancing the efficiency of the system.Finally, based on the main power boost circuit and the DSP controller successfully built the hardware test platform for photovoltaic systems. Fuzzy control and fuzzy PID control method take maximum power tracking in hardware platform for photovoltaic power generation system. The results further show that the fuzzy PID control method has the features of fast response, high stability, high accuracy, good robustness.