Study On Black Start Scheme Of Microgrid

When the micro-grid is in full-black state,a good black-start scheme can not only ensure the supply of critical loads in the micro-grid,but also ensure the continuous and stable operation of the micro-grid.Under certain conditions,the black-start power for the restoration of the large power grid can be provided,which can effectively reduce the traditional power system in the black-start process because the selection of hydropower units furthers the load center as a result of the black-start process.The influence of generator self-excitation and overvoltage caused by black-start power supply can restore the system from point to area,shorten the recovery time of the whole system,and reduce the economic losses caused by the power outage.Therefore,the research on black-start scheme of micro-grid is of great significance.Aiming at the problems involved in the black-start scheme of micro-grid,a detailed analysis and research are carried out in this thesis.Firstly,the structure of micro-grid,the control strategy of micro-power and the content of black-start scheme of micro-grid are analyzed in detail.According to the different control strategies of different types of micro-power,the models of different types of micro-power are established,which lays a foundation for the formulation of black-start scheme of micro-grid.Secondly,the traditional droop control strategy cannot be applied to the black-start scheme of micro-grid because the transmission line of micro-grid is short and resistive.The virtual impedance is added to the traditional control method to change the system from resistivity to inductance,which improves the traditional droop control strategy and solves the problem that the traditional droop control strategy cannot be applied to micro-grid.The problem of black-start scheme of power grid will also be proposed here in this thesis.Then,according to the control mode of black-start in micro-grid,the black-start power supply is selected,the grid restoration strategy is studied,the failure factors of black-start are analyzed and the countermeasures are given.Finally,according to the characteristics of independent micro-grid and micro-grid system,the black-start strategies for these two systems are given respectively.The independent micro-grid adopts the recovery strategy of serial recovery,and the multi-micro-grid system adopts the recovery strategy of combining serial recovery with parallel recovery,which makes the micro-grid have good black-start ability.In order to verify the correctness of the black-start scheme adopted in this paper,two models of different structures of micro-grid black-start strategy are built using PSCAD simulation software.The simulation results verify the feasibility and validity of the proposed black-start scheme for micro-grid.