Study Of Photovoltaic Improved MPPT Algorithm And Three-level On-grid Inverter Control Strategy

With the development of economic and social progress，traditional fossil energy has beenalmost used up，and mankind is faced with the challenge of sustainable development．Solarenergy as a one of new energy development provides a new development idea because it ispollution-free，reproducible and widespread．At first，the paper studies the photovoltaic battery MPPT algorithm．The existing twoclassical algorithms (incremental conductance method and Perturbation and Observationmethod) were improved．Because the traditional incremental conductance method andPerturbation and Observation method exist that tracking speed is slow and concussionamplitude is big near the maximum power point，and the paper puts forward an improvedvariable-step conductance incremental method and Three-Point comparison variable-stepPerturbation and Observation method．These two methods are almost to overcome theshortcomings of the traditional algorithm．Simulation was carried out，and the results showthat the proposed algorithms are effective．Furthermore，this paper also studies controlstrategy of photovoltaic inverter．First of all，the basic working principle of mufti-levelinverter is introduced in the paper．Taking NPC three level inverter as the object of study，thispaper expounds basic principle of two control strategy (SPWM technology and SVPWMalgorithm)．Especially, the paper mainly studies the SVPWM control strategy．Throughstudying the judgment of sector of reference vector，selection of action time of space voltagevector and judgment of function sequence of switch vector etc，the effective SVPWM controlstrategy was obtained．In addition，through establishing the simulation model in theMATLAB/SIMULINK and comparing the simulation results，the results prove the superiorityof SVPWM．...