| With the background of new power system,grid-connected new energy,represented by wind power and photovoltaic,on the one hand reduces environmental pollution and dependence on fossil energy;on the other hand,its intermittency and unpredictability change the structure of traditional power grid,thus bringing new challenges to the frequency stability of regional power grid.As an important indicator to measure power quality,power grid frequency change is of great significance to the safe and stable operation of power system.However,frequency regulation mode based on traditional thermal power and hydroelectric power frequency regulation units has been unable to better adapt to and meet the needs of future power system operation and development due to its slow response speed and low unit climb rate.Therefore,it is urgent to study new Frequency regulation means to assist the power grid to carry out Load Frequency Control(LFC)efficiently.The main research contents of this paper are as follows:(1)The LFC technology of two area interconnected power system based on chaotic particle swarm optimization fractional order PID control is proposed.Firstly,the working principle and application scenarios of primary frequency regulation and secondary frequency regulation of power system are discussed,and then the dynamic model of frequency regulation of the power grid is constructed,mainly including prime mover and its governor model,generator-load model and tie line model,and nonlinear factors such as governor dead zone,generator change rate constraint and transmission delay that occur in actual operating conditions are considered,and a fractional order PID controller based on chaotic particle swarm optimization is designed,and single-area and two-area LFC models are constructed.Finally,the stability and effectiveness of the proposed frequency regulation system is verified by simulation.(2)The LFC technology of hybrid energy storage system composed of energy storage battery and supercapacitor is studied.Firstly,the challenges faced by a single energy storage system in assisting grid frequency regulation are discussed,and then the concept of hybrid energy storage is proposed,which can effectively meet the higher requirements of frequency regulation requirements under the new power system,and then the LFC model of hybrid energy storage system is constructed,and the hybrid energy storage joint frequency regulation model is constructed on the basis of the mathematical model of energy storage battery and super capacitor.Finally,the simulation results show that the hybrid energy storage mode can maintain good frequency regulation performance under different disturbances.(3)Explore the electric vehicle-hybrid energy storage system auxiliary power grid LFC technology including load access of electric vehicles.Firstly,the advantages of electric vehicle assisted grid frequency regulation are analyzed,and then the model of electric vehicle load participating in grid frequency regulation and charge-discharge strategy are studied.Then,the LFC stage control model of EV assisted power grid with hybrid energy storage is built,and the hybrid energy storage stage control strategy is proposed.Finally,the proposed model and the control strategy are verified by simulation.The simulation results show that the electric vehicle has good dynamic performance and stability when it is connected to the mixed storage grid under different disturbances. |
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