Research On Adaptive Control Strategy Of Energy Storage Converter Power Grid

With the global energy shortage and environmental pollution problems becoming more and more serious,the construction of renewable and clean energy-based energy architecture has become a core strategic initiative for industrial development in various countries.However,with the "high proportion" of random and fluctuating wind power and photovoltaic distributed power sources into the grid and the "high proportion" of power electronic interface inverter access,the quality of microgrid power supply is seriously affected,and the microgrid in the "Under weak grid conditions,the conventional control strategy will introduce background harmonics into the grid,which will seriously affect the stability of the system.As the core equipment of renewable energy generation system,the Power Conversion System(PCS)is responsible for bi-directional energy circulation,power conversion and stable system operation in microgrid:(1)This paper analyzes the problems brought by new energy generation such as wind power and photovoltaics faced by the current power grid,introduces the basic functions and topology of PCS as the core equipment of energy storage system,explains the application fields and advantages and disadvantages of each topology,expounds the main content of power grid adaptability,and summarizes the current control strategies of PCS in suppressing harmonics,three-phase imbalance,frequency fluctuation and other aspects of improving the adaptability of the power grid.(2)The mathematical modeling and small signal linearization of the adopted PCS topology are carried out,the basic control block diagram under the grid-connected and off-grid PCS is established,and the LC filtering parameters of the circuit are designed according to the power level,which provides the theoretical parameter basis for the experimental simulation verification part.(3)With the basic functions and auxiliary expansion functions of PCS as categories,control the charging/discharging of PCS grid-connected operation under the basic functions,as well as the output of switching and off-grid operation and merger/off-grid switching;The grid-connected harmonic current suppression and off-grid three-phase voltage imbalance control to improve the adaptability of PCS power grid under the auxiliary extension function are controlled,and the corresponding control block diagram is drawn,and the corresponding simulation model is built by Matlab/Simulink simulation software to verify the correctness of the control strategy.(4)The characteristics of weak power grid and the impact on PCS control are analyzed,the equivalent output impedance model of PCS is established by using the impedance stability analysis method,the disturbance caused by the weak power grid is studied,the relationship between the power grid impedance and the stability margin of the PCS system under the working conditions of the weak power grid is analyzed in the form of a Bird diagram,and the active damping current loop feedback is added on the basis of the existing control strategy,the capacitor voltage feedforward is improved,and an improved LC filter capacitor voltage feedforward control strategy based on DSOGI under the PCS weak grid is proposed.Optimize the output waveform under weak power grid,improve the power grid adaptability of PCS,and build corresponding simulation models through Matlab/Simulink simulation software to verify the correctness of the control strategy.(5)Drawn,weld and debug PCB boards to provide board guarantee for semi-physical experiments;A semi-physical simulation platform based on the P6016 series of Yuankuan Energy was built to further verify the correctness and feasibility of the control strategy adopted in this paper.