Research On Grid-Connected Power And Soc Balance Control Of Chain Energy Storage Converter

With the increasingly serious environmental problems and the exhaustion of fossil fuel reserves,renewable energy has received widespread attention.High-voltage and high-power energy storage technology has become an important auxiliary means for high-permeability new energy grid connection.Phase H-bridge chain connection composition has the advantages of high equivalent switching frequency,low output voltage harmonics,easy modular expansion and easy fault redundancy control,and is very suitable for high-voltage and high-power energy storage occasions.Therefore,this article mainly focuses on the three-phase grid-connected power control of the three-phase chain-type energy storage converter,SPWM modulation,and multi-module energy storage battery SOC phase-to-phase and intra-phase balance control.First,based on the established mathematical model of the chain-type energy storage converter under the two-phase rotating coordinate system,the grid-connected power control strategy is analyzed to realize the active and reactive power decoupling control,which is verified by simulation.Secondly,research on the modulation strategy of the chain-type energy storage converter.The chain-type energy storage converter is a multi-level converter.In this paper,the carrier phase-shift modulation applicable to the chain-type energy storage converter is analyzed in detail.The following output characteristics are analyzed,and a modulation method based on hybrid unipolar carrier phase shift is proposed.Thirdly,aiming at the unequal state of charge(SOC)of each battery in the chain-type energy storage system,this paper carried out the research of SOC phase-to-phase equilibrium and phase-to-phase equilibrium.Aiming at the problem of phase-to-phase SOC balance,the traditional zero-sequence voltage injection’s phase-to-phase SOC balance control strategy is analyzed,and on this basis,a control strategy that can speed up the SOC balance speed is proposed,which is based on the additional power loop-based phase-to-phase SOC balance control.Furthermore,aiming at the intra-phase SOC equalization,a fast intra-phase SOC equalization control strategy was proposed,and the three possible cases of reverse superimposed modulation voltage are studied,finally the proposed fast intra-phase SOC equalization control was verified through simulation results.Finally,on the basis of theoretical analysis and simulation verification,an experimental platform of chain energy storage converters was designed,including hardware design and software design.Through this experimenta1 platform,the carrier phase-shift modulation,grid-connected control and SOC equalization control were experimentally verified.