Research On MPPT And Islanding Detection Of Grid-connected PV Power Generation System

With the rapid increase in the environmental costs of fossil fuels,many countries are seeking to meet their energy needs through solar energy.Thus,it is imperative we ensure we are being as efficient as possible in absorbing solar energy.This dissertation will focus on photovoltaic generating systems research.The main focus being: Maximum Power Point Tracking,Islanding Detection and the Maximum Power Point Tracking Control System.The main research contents are as follows:1.Due to the changesin the external environment,photovoltaic cells’ U-I characteristic curve hasnonlinear、multipolar point features.This dissertation studies the theory of photovoltaic cells,and howit’s mathematical model is established and the simulation experiment is carried out.Under this condition,the regularity of U-I characteristic curve of photovoltaic cellswas obtained.Based on this,a new method of MPPT is proposed.The corresponding simulation model is established,and on the experimental platform the superiority of the proposed method is verified.2.Duringthe working period of the photovoltaic system,a power blackout may cause islanding.This will cause damage to the equipment or may even result in casualties.So the islanding detection is a very important part of photovoltaic system.In this paper,the commonly used islanding detection methods are analyzed,and a short detection time and small non-detection zone method is introduced.The method is verified by simulation in power grid failure,rapid response,and has the characteristics of Asmaller non-detection zone.3.Designed and implemented a photovoltaic MPPT experimental platform.The control hardware is the BOOST converter and the software is based on the embedded system.Using the actual output PWM waveform to control the system.Experiments demonstrated that the new method can track MPP faster and at a more stable rate.