Research On Reactive Power Flow Control And Voltage Stability Of Microgrid

Microgrid has become an important way to realize the efficient access of new energy power generation and improve the power supply reliability. The research on the stability and optimal control of the system has received widespread attention. The operation stability of microgrid is closely related to the power flow and its distribution. The optimal reactive power flow control has important effect on the voltage stability of the microgrid system. Aiming at the characteristics of microgrid system operation depends on inverter interface, the control strategy of microsource inverter based on reactive power flow optimization and the voltage stability of microgrid are studied in this paper.In order to improve voltage stable of microgrid when the loads change under island mode, in this paper, the relationship between reactive power flow of microgrid and voltage stability is analyzed, and the importance of rational optimization of reactive power flow distribution for the voltage stability is elaborated. Due to the lack of droop control in voltage stability, the feeder power flow control is adopted in this paper. Aiming at the case of it is difficult to obtain a higher voltage precision when the load variation is large, a reactive power flow control strategy based on droop control is proposed in this paper, and the calculation method of the feeder power flow reference value is presented according to the load size and the variation of the load. Assigning loads reasonably based on the power flow allocation factor on the feeders, the amount of reactive power unbalance assigned to each microsource inverter, so that each microsource inverter adjusts the output reactive power of its own, to achieve a reasonable distribution of reactive power on the basis of local balancing. The specific pathway of this method is that each microsource inverter undertakes its local load respectively, and for the public load, shared by all microsource inverters according to the different line impedances. This method can control real-time reactive power flow distribution on the feeders, coordinate the circulating of reactive power flow between the various feeders, and remain voltage constant in nominal voltage to achieve higher voltage steady state accuracy even if the system suffered severe disturbances.On the basis of the simulation and analysis of Matlab/Simulink, the experimental platform of microgrid is built, and the feeder power flow control experiment of dual machine microsource based on reactive power flow optimization and stability analysis is completed. Simulation and experimental results show that the introduction of reactive power flow optimization based on the droop control can significantly improve the voltage stability of microgrid system.