Research On Control Strategy In Dual Mode Of Wind-PV Hybrid Micro-grid System

Since the beginning of the twentieth century,environmental issues have attracted more and more attention from countries all over the world.Excessive harmful substance emissions and unsustainable self-use of resources are all negative impacts of global energy on the environment.On the other hand,the demand for stability of power supply is constantly increasing.In view of this situation,distributed generation(DG)has developed rapidly.Although DG can solve environmental problems,there are still many problems,such as inadequate stability,unpredictable power supply and so on.Therefore,DG,such as wind power and photovoltaic power,can play an important role in power supply stability and high quality power supply.The normal operation of the micro-grid system includes the grid-connected mode connected to the public grid and the isolated mode isolated from the public grid.The micro-grid system should switch reliably between the grid-connected state and the island state.It is necessary to study reasonable control strategies to effectively control the status switching and operation process of the micro-grid,so as to ensure the high quality operation of the system.The micro-grid of this subject is composed of wind power and photovoltaic,and two kinds of operation states and state switching process are studied in depth.The micro-grid of this topic is composed of wind power and photoelectric power,The mathematical model and operation characteristics of two modules of wind power and photo-electricity in wind-photovoltaic micro-grid system are analyzed.Due to the "congenital" deficiency of the traditional droop control,it is proposed to improve the V/F droop control mode as a replacement,so as to ensure that the system voltage and frequency can maintain a constant value basically unchanged or with little fluctuation.Therefore,the control mode of this project is divided into two types,namely,PQ control and the above V/F droop control.At the end of this paper,the simulation model of micro-grid is built by means of simulation tools.and the two operating states and state switching process of the wind-scenery micro grid system are studied in depth.Through the simulation examples,the influence tests on the power supply quality of the system are carried out under the conditions of isolated island,grid-connected and load switching,as well as the influence tests on the power supply quality of the system under the conditions of switching,and the control strategy of this study is proved to be of practical popularization value.