Research On Photovoltaic Grid-connected Inverter Control Strategy And Its Island Detection

Facing the problems of energy crisis and environmental pollution,the development and utilization of new energy have attracted attention from all sides in today's society advocating sustainable development,and solar power generation technology is the focus of most attention.Therefore,how to make full use of solar energy,improve the efficiency of light energy conversion and how to deal with the isolated island caused by local power grid failure are the research objectives of this paper.First of all,the photovoltaic cells are deeply analyzed.The specific research contents include: Firstly,the working principle of photovoltaic cell and its mathematical model are briefly introduced.According to the mathematical model,a general engineering simulation model of photovoltaic cell,photovoltaic module,is built using MATLAB simulation software.At the same time,according to the parameters provided by the photovoltaic cell manufacturers,different light intensities and different ambient temperatures are respectively input into the photovoltaic module,and the simulation output and curves are compared and analyzed to study the influence of different light conditions and temperature conditions on the output characteristics of the photovoltaic cell.Then,the working principle of the control algorithm is introduced,and two popular MPPT control methods are analyzed,namely,constant voltage method and conductance increment method(including constant step disturbance and variable step disturbance).Through MATLAB simulation environment,the corresponding simulation models are built respectively,and the same environmental parameters are input for simulation research.The curves of tracking the maximum output power point of several control methods under the same external conditions are compared and analyzed,and their respective advantages and disadvantages are compared.Then,the control methods of three-phase photovoltaic grid-connected inverter are studied,including control,current closed-loop decoupling control and model predictive control.Through designing simulation parameters and building simulation models,the advantages and disadvantages of various methods are studied.In addition,a new type of filter is introduced to solve the problem of higher harmonics of grid-connected inverter output.Finally,in order to deal with the danger of island effect caused by sudden power failure,an island detection unit is added in this paper.Starting from the simple detection method,the simulation research is carried out,and then the simulation model of the three-phase detection method is built on this basis,and the simulation experiment is carried out.Finally,the advantages of the method are demonstrated by comparing the simulation experiment results of the three-phase detection method and the three-phase AFD detection method.Figure [71] table [6] reference [53]...