Research On Control Strategy Of Micro–Grid And Off–Grid Operation

The operation mode of the microgrid includes both grid operation and island operation.The microgrid can run smoothly depends on whether the two modes can be smoothly converted.However,the conversion between these two modes and how they are controlled is very worthy of further study.For the traditional distribution network,the access of the distributed power supply has a greater impact on it,from the original single-supply radial distribution network into a power supply and load over the power system,which makes micro-grid control system has become more complex.The traditional centralized power supply system of centralized power supply system is single,centralized and inflexible,but the distributed power supply system is diversified,decentralized and highly flexible.Therefore,the distributed power generation system has become the research hotspot and development direction of the power industry.The inverter is the core device connecting the large power grid and the distributed power generation unit.It is very important to study the inverter and its control strategy,Of course,this is carried out under the premise of ensuring that the output voltage and current meet the grid requirements and load requirements.In this paper,the distributed power generation system inverter is used as the research object,and the seamless switching control between the grid-connected and the islanding operation mode is studied.First,the control mode of the inverter(PQ control,V/f control)is studied when the microgrid is carried out and run off-grid.Secondly,for a variety of distributed power generation system inverter when it is running mode switching,we make the appropriate changes for control strategies in order to achieve a smooth handover of the problem.And we propose a varied inverter coordinated control strategy which is based on indirect current-controlled.By introducing coordinated control link,while achieving the main inverter V/f control and PQ control seamless switching.We establish a mathematical model of distributed power generation system based on the control strategy.Then,simulation results verify the validity of the proposed control strategy.