Research On Control Strategy Of T-type Three-level Power Conversion System Based On Battery Storage

The excessively consumption of the non-renewable energy hasbrought great prosperity to the human society, but energy shortage andenvironmental pollution have also been brought. The utilization ofdistributed generation can convert the renewable energy to grid, which isa good way to sovle the problems.In this paper, the realization strategy isstudied based on the related battery storage technology.Power conversion system is the interface between battery and grid,which is very important to the battery storage system. This paper studiesa bi-directional power conversion system which is suitable forhigh-capacity battery storage. The system uses a three-phase three-levelT-type topology and takes the lithium battery as energgy carrier. Bycharging and discharging the lithium battery, the PCS can work in fourquadrants.Firstly, this paper describes the relevant contents of the batterystorage system, and some common converter topologies are reviewed.Secondly, the principle of the T-type three-level topology is studied. Bymodeling the mathematical model of the bi-directional power conversionsystem, the space-vector control algorithm is analyzed and the three-level SVPWM modulation algorithm is studied. This paper introduces thecause of the unbalancing problem of neutral-point voltage and thenproposes a method to settle the problem. Thirdly, the losses of the T-typethree-level converter and the traditional two-level converter are calculatedand then a comparative analysis is made. Finally, by constructing a100KW full digital prototype, the proposed theories and methods arecomprehensively validated. The experiment results show the PCSmeeting the requirements of PWM converter used in battery storagesystem.