Research On Stable Operation And Reliability With Multi-energy Storage Microgrid

As the microgrid becoming an important auxiliary means for some developed countries to solve many problems in the power system,the problem of stable operation of the microgrid becomes important.For the microgrid system including wind power,photovoltaic,diesel generator and battery storage,the cooperative control and optimal of power distribution between power sources are the main issue in the application of the microgrid.This thesis mainly studies the operation control and reliability evaluation of microgrid under multi-storage regulation.(1)The mathematical model of each key unit in the microgrid are constructed to study the coordination between multiple energy storage.Established a mathematical model of wind turbines,photovoltaic arrays,diesel generators and energy storage systems in the microgrid.In this chapter,a hybrid energy storage system consisting of all-vanadium flow battery and supercapacitor is used.The coordinated control strategy of parallel operation of multiple energy storage units is analyzed.The equivalent energy storage model of all vanadium redox flow battery and supercapacitor is established.Moreover,the circuit model and control principle of bidirectional DC/DC converter are studied.This study proposes a hybrid energy storage control strategy based on all vanadium redox flow battery-supercapacitor and the modeling analysis is carried out.(2)A fuzzy droop control strategy based on sliding mode algorithm is proposed to control the stable operation of the microgrid.The existing method applied to power supply systems with the characteristic of multipower supply is difficult to achieve fast dynamic response,high stability,and robustness problem.Therefore,a self-learning fuzzy control theory is proposed in this paper to model the traditional power-voltage droop control system as a whole.Considering the uncertainties of the unmatched parameters,a novel optimal control strategy based on fuzzy sliding mode droop control is proposed.A sliding mode droop controller with fast response is designed.The desired smoothing output trajectory is used to describe the state and control variables of the system.Moreover,the robust stability control of voltage and the accurate distribution of power are realized.Finally,the effectiveness of the method is demonstrated by a practical example.(3)Based on the characteristics of reliability evaluation of island-type microgrid,this chapter proposes a Monte Carlo reliability assessment method based on timing characteristics,analyzing the output characteristics and operating characteristics of distributed power supplies,and simulates the timing status of all components in the network.On the basis of the research,the operation control strategy of multiple energy storage devices is studied;Research on load reduction strategies for different load levels.The effectiveness of the proposed reliability assessment scheme is demonstrated by different power supply capacity allocation schemes.