Research On Microgrid Operation And Control Strategies

With the depletion of fossil energy and the pollution of atmospheric environment,new energy power generation has played an increasingly important role,and the distributed generation generated by new energy generation is connected to the traditional large power grid through the micro-grid;the micro-grid should be combined with the large power grid to form an efficient and flexible system,which can not only achieve stable operation within the micro-grid,but also achieve smooth operation with the large power grid.Connection,the realization of this goal depends entirely on effective micro-grid operation control strategy,so the research of micro-grid operation control strategy is of great significance.Aiming at the problems involved in the operation control strategy of microgrid,this paper studies deeply from two aspects: the control strategy of micro-power supply and the coordinated operation control strategy between micro-power supply.Firstly,the structure of microgrid is analyzed.Based on the characteristic that most micropower sources in microgrid are inverters,the mathematical models of three-phase inverters and LC filters are established,and the parameters of LC filters are designed.The simulation results show that the designed filters can suppress harmonics and improve the output impedance of inverters.Secondly,the control methods of micropower sources in microgrid are studied.According to the characteristics of traditional droop control,because the sag coefficient of P-f and Q-V curves is too large,the power output is too narrow,and the micro-source output is not timely and the dynamic response is slow,an improved droop control method is studied.Three large sag coefficient curves are used to replace the original small sag coefficient curves.The feasibility and effectiveness of the improved droop control are verified by simulation and comparison.Superiority.Then,aiming at the problem of coordinated operation control among micro-power sources in micro-grid,the characteristics of master-slave control,peer-to-peer control and hierarchical control of micro-grid are analyzed,and the peer-to-peer control strategy suitable for controllable micro-power sources is studied.All micro-power sources in this method adopt improved droop control.Based on the peer-to-peer control strategy,a synthesis of controllable micro-power sources and uncontrollable micro-power With the control strategy,the uncontrollable micro-power supply adopts PQ double-loop control,and the controllable micro-power supply adopts improved droop control to ensure maximum output of power,fluctuation of voltage and frequency within a reasonable range,and stable operation of the micro-grid.Finally,a simulation model of peer-to-peer control and integrated control is built on matlab/smulink platform.The simulation results show that the two control strategies can not only maximize the output power of micro-power supply,but also maintain the stability of system frequency and voltage in the switching process,which proves the feasibility and effectiveness of the control strategy.