The Research On Theapplication Of Predictive Control In Three-level Grid-connected PV System

With aggravation of global energy crisis and environment pollution, due to theimportant status of solar power in the global power energy system, solar resource hasthe potential to be the main alternative energy source to replace traditional ones in thefuture. Therefore the study of PV grid-connected generating technology is asignificant research field. This thesis focuses on control strategies in three-level NPCgrid-connected PV systems, which includes maximum power point tracking(MPPT)methods for PV arrays and the current control methods of three-phase PVgrid-connected inverter. The former control method aims to take more good use of PVsystem, and the later aims to produce sine current that is in phase with the grid.Firstly, according to the electrical characteristic of solar cell, its physical andmathematical simulation model has been established in the thesis. Also combined withthe output characteristic under different environment, the advantages andshortcomings of the typical maximum power point methods have been analyzed andstudied, the problems of hot spot effort、tracking losses and efficiency have beenintroduced. Then, take the great advantages of three-level NPC grid-connectedinverter into account, compared with the traditional two-level inverter, an especiallydetailed research has been made which including its work principle and SVPWMmodulation principle conducted. Meanwhile, for the sake of the disadvantages in thecontrol method of the three-level grid-connected inverter, a control technology basedon the Predictive Control has been proposed. At last by building the experimentalmodel which presents the predictive control process of three-level NPCgrid-connected inverter, the experimental results verify its the effectiveness andfeasibility.