Development Of Intelligent Circuit Management For Distributed Photovoltaic Power Station

The distributed(photovoltaic power)PV power station has drawn much attention due to its convenience and economy.However,the power output of PV module is affected by the changes of light,random occlusions and uncertainty load.Distributed PV stations connect to the grid from distribution network,and it will affect the security of grid.So the development of distributed PV station is restricted.The commonly used Maximum power point tracking algorithm is based on the PV module output U-P curve.However different connection of PV modules and the production of PV modules result in diefferent U-P curve.There are always the contradiction between the efficiency and accuracy,and the contradiction between the accuracy and applicability.In this case,it is important to study the efficient maximum power point tracking algorithm and reliable anti-islanding detection.The details of this paper are as follows:1.We firstly introduce the internal mechanism of the photovoltaic cells,and analyze the photovoltaic cells output formula and the simplified internal circuit diagram.Based on the formula,the simulation model is established in the MATLAB/SIMULINK,and the output characteristic curves of the photovoltaic modules are displayed through the simulation.2.Based on analyzing the traditional algorithm,the dynamic equivalent impedance matching(EIM)algorithm was presented.The EIM algorithm does not rely on photovoltaic modules output curve.The unknown of the equation and the duty ratio,can be obtained through the iterative method,3.The simulation model is established in the MATLAB/SIMULINK.The dynamic impedance matching algorithm is realized by compiling S function.The simulation model proves the reliability of the dynamic impedance matching algorithm by comparing the traditional incremental conductance method and variable step size conductance increment method.4.A test platform for the simulated sunlight has been set up.The control algorithm is realized by Stm32.And the DC-DC converter is designed based on the H bridge.Good results were obtained by making a contrast variable step size conductance increment method.5.Based on the analysis of classic active anti-island detection and passive anti-island detection algorithm,a novel anti-island detection is proposed,which is based on the wavelet transform.This method detects an island by the harmonic characteristics from the wavelet transform.The simulation grid model is establised on MATLAB/SIMULINK,and good results have been achieved by comparing the short-time fourier transform.