Research On Coordinated Control Strategy Of Microgrid With Distributed Generation

The output power of distributed generation such as solar energy and wind energy is unstable,and it will adversely affect the stable operation of the microgrid when connected to the microgrid,and the energy storage system can provide energy buffer for the microgrid and keep the voltage and frequency of the microgrid stable.Therefore,the role of energy storage systems in the safe and stable operation of microgrids has gradually become prominent.In order to provide users with more reliable and high-quality electrical energy,and at the same time achieve friendly interaction with the large power grid,the coordinated control of distributed generation and energy storage systems in the microgrid is very important.In this context,this paper studies the coordinated control of microgrids containing distributed generation and energy storage.The main work is as follows:First,the concepts,characteristics,grid connection characteristics,development status at home and abroad,the definition of micro-grid and development status at home and abroad are expounded,and the research status of micro-grid coordinated control strategy is analyzed.Taking distributed generation and microgrid as research background,mathematical models and control models of photovoltaic power generation system,wind power generation system,lithium iron phosphate battery and supercapacitor energy storage system were established,and the characteristics of photovoltaic and wind turbine were carried out on MATLAB simulation platform.The simulation verification lays the foundation for the study of coordinated control of the microgrid.Secondly,the basic principles and functions of distributed power grid-connected inverters are studied,the principle and mathematical model of the grid-connected inverter are analyzed,and the control strategy of the grid-connected inverter is mainly studied,and the work of common control methods is analyzed in detail.Principle,the double closed-loop control strategy of the voltage outer loop and current inner loop of the grid-connected inverter is studied,and the simulation model of the micro-power grid connection operation is established,and the micro-grid is simulated and studied under the condition that the load power changes in the micro-grid to verify the correctness of the simulation model.Then,the hybrid energy storage coordination control strategy of the lithium iron phosphate battery supercapacitor in the grid-connected microgrid is studied.The shortcomings of the traditional PI control strategy used in the power converter of the hybrid energy storage system are analyzed,and it is proposed for that both the voltage loop and the current loop of the power converter adopt the auto disturbance rejection control strategy.The first-order filterpower coordination distribution strategy has been widely used in hybrid energy storage systems.In order to better coordinate the power distribution between lithium iron phosphate batteries and supercapacitors and optimize the operation state of the hybrid energy storage system,a second-order filter is designed.The device suppresses power fluctuations.By establishing a microgrid simulation model containing distributed generation such as wind and light and hybrid energy storage systems,the effectiveness of the proposed auto-interference rejection and second-order filter composite control strategy is verified on the MATLAB simulation platform.Finally,the active power coordination control strategy between distributed power and hybrid energy storage in the island microgrid is studied.The master-slave control strategy of the island microgrid is analyzed,and the island microgrid networking method studied in this paper is established.The photovoltaic power generation system,wind power generation system,lithium iron phosphate battery energy storage,supercapacitor energy storage,important load and general load are considered.Factors affecting the smooth operation of the island microgrid,the active coordinated control between these factors was studied,and the simulation study was carried out by building a simulation model in MATLAB to verify the correctness and effectiveness of the proposed active coordinated control strategy.