Research On Control Technology Of The Tidal Current Energy Grid-Connected Inverter

With the development of the new energy sources, the Ocean Tidal Current Energy, as a popular branch of it, attracted a lot of attention. As the further research and the gradual expansion of its use, the Grid-Connected Tidal Current Energy technology also had been developed. In this context, on the basis of reading a large amount of literature, this paper mainly studied on the Grid-Connected Inverter technology of the Tidal Current Energy system.Compared with several topology structure of the inverter,combined with actual situation,it chose an appropriate structure for this paper, on this basis, it built the circuit model and the switch state model in the abc coordinate system and the dq coordinate system. This would provide the mathematical theory basis for the next study of the inverter ontrol technology.In the Tidal Current Energy system, the structure of the power conversion device would influence the performance and the efficiency of the system directly.This paper used a structure of double PWM inverter of the variable speed-constant frequency direct drive of the Tidal Current Energy system. The advantage of this structure is that the grid side and the generator side can work in high power factor with low current harmonic.The generator side rectifier used an algorithm of variable step length MPPT control method, it can track the rapidly changed water flow rate and not cause the shock of the system at the maximum power point. The grid side inverter used a control strategy of double closed loop of voltage and current with the grid voltage feedforward control. The control would be simple and the power factor was high. In the paper, the voltage loop was designed as a typical second-order system and the current loop was designed as a ? type system. It analysed the function of the grid voltage feedforward control, at the same time, used a method of the software phase-locked loop method to ensure the inverter worked successfully.On the basis of the study of the control strategy theory, it also built an actual phototype,including the main circuit, the control circuit with ARM and the IGBT drive circuit. The main circuit contains DC capacitance, IGBT bridge arm and the LC filter.The paper also used the MATLAB/Simulink to have theory study, and simulated the whole system to provide the feasibility of the actual phototype.At last, it debugged the phototype to verify the correctness and the feasibility of the strategy.