Research On Multi-string Maximum Power Tracker For Grid-connected Pv System

At present, the world’s energy situation is urgent, the development and utilizationof renewable energy has become the important measures to safeguard energy security,The solar energy resources is abundant and clean, So which is widely used. The outputof photovoltaic (PV) array is influenced by the environmental factors such asirradiation and temperature.Maximum Power Point Tracker (MPPT) is usually used inPV systems to track the maximum power point and match the array and the loads.Amulti-string MPPT for small-scale grid-connected PV system is presented in the thesis.Multidrop maximum power tracking of grid inverter can maximize the use ofsolar energy, effectively overcome the disadvantages that the whole power coastdownwhich brought by power mismatch of branch, and which can minimize the systemaffected by single branch fault, has great application prospect. At first, this paperanalyzes the advantages and disadvantages of all kinds of maximum power trackingalgorithms, and then which carrys on the Matlab simulation and experimental analysis,and finally a simple for multidrop maximum power tracking algorithm was adopted.In this paper, a3kW dual branch maximum power tracking of photovoltaic (PV)grid system has been designed, each branch contains MPPT of photovoltaic arrayindependently, makes full use of the energy, the conversion rate of system is improved,then which the simulation has been carried on. Finally The system control chip ofdigital signal processor TMS320F2812is used, implement digital control scheme, andsets up the experimental platform,To reach what the preceding stage of the doublebranch respectively realize MPPT, Before and after the two level under the action ofdouble loop control method has been stable,and parallel experiments are effectiveimplementation.The experimental results illustrate that the hardware and software designisfeasible and satisfactory.