Research On Maximum Power Point Tracking Algorithm Of Single-phase Single-stage Grid-connected Pv System

Electricity is an important carrier of energy, but the traditional fossil fuels which was used to create electricity is facing increasing depletion and environmental pollution problems generated by the combustion process, which has become a major bottleneck to hinder the development of the world economy. In order to resolve the energy crisis, reduce environmental pollution and achieve sustainable economic development, vigorously develop green renewable energy is the current urgent task of whole mankind. This paper consider the application of small rooftop photovoltaic power generation system as the background, and improve overall system efficiency and output power quality as the crucial point, and single-phase single-stage grid-connected PV systems as the object of study, the parameters of main circuit and Controller Optimal, and the maximum power point tracking (MPPT) algorithm were study. The full text including the following aspects:The mathematical model of the PV array was Established, based on the mathematical models the output characteristics of photovoltaic arrays were simulated using MATLAB software; several commonly used photovoltaic inverter topologies were analyzed, and their advantages and disadvantages were summarized, and the topology of this paper were determined through comparative analysis, and the main circuit of the LCL filter parameters were detailed designed, the performance of the LCL filter and effect of grid uncertainties on the LCL filter were analyzed.Conventional PI controller have principle error in tracking a sinusoidal reference current signal, so this paper use the proportion-resonant control as the inner current controller, at the same time the controller parameters were detail designed, including the proportional coefficient, integral coefficient and damping coefficient, and the general approach of the current controller parameters design was summed. Because Single-stage grid-connected photovoltaic system reference current amplitude contains second harmonic components, in order to prevent the reference current to have harmonic, we consider increase a zero-order hold in front of the PLL block. Finally, from the simulation we can seen that through the method of parameters design,good steady state and dynamic effects of the system were ensured, and good output power quality were also ensured.This paper focuses on the maximum power point tracking (MPPT) control method of the photovoltaic array, first this paper point the shortcomings of the traditional MPPT method in the practical application, and then proposed the MPPT control method used in this article. This paper analysis principle of extremum seeking Algorithms in detail, and propose the controller optimization method. From the simulation it can be seen that modified extremum seeking Algorithms has a distinct advantage in the dynamic performance and accuracy compared to traditional extreme seeking method and the perturbation-observation method.A200W experimental prototype was produced to validate the proposed control algorithm, the prototype hardware circuit and software flow chart were analyzed and described, the experimental waveforms were given at the last, from the experiment we can see that the experimental results meet the design requirements and the correctness of the argument proposed in this paper were proved.