Research Of Micro-grid And Its Control Strategy

Micro-grid as a flexible operation and simple control generation is put forward because the disadvantages of power grids,large units and high voltage of centralized power supply becomes obviously.Micro-grid has been called more and more widespread concern and attention because it can achieve the full utilization of distributed generator and meet the diversity of users.Each micro-source accesses the micro-grid with the help of power electronic devices.Power electronics make the control system becoming more complicated.Meanwhile,when the normal operation of the micro-network,we must consider the coordinated control strategy in order that each micro source should be operated reasonably and stably.A better control strategy makes the advantage of micro-grid play effectively.This paper hopes to find a more appropriate control strategy of micro-grid.First,the paper studys the master circuit,the basic control strategy and basic control methods and the control principle of the master controller and makes some corresponding modeling,design and simulation.and we can find something to prove and the micro-grid can run stably.The master-slave control strategy is a common control method used in micro-grid.In this control method,One or more distributed generators(or energy storage device)is the master,which services as a frequency and voltage reference for other slaves in island mode.In order to avoid the switch of control method of the master in master-slave control,that an proved design of the master is proposed to automatically change the control structure and the control method of the master can implement multi-modal switching operation of the master and guarantee the smooth transition from grid-connected mode to islanded mode.Considering the problem of synchronization,the grid synchronization control is improved with the cross product of voltage vecters to effectively reduce the impact on low voltage grid systems when reconnecting the DG to the grid.Finally,a simulation platform of micro-grid is built on the MATLAB/Simulink software.The simulation results show that the proposed method can satisfy the control requirement in both island and grid-connected mode,and ensure the smooth transformation of the two modes and achieve the expected control purpose.