Research on Quasi-Synchronous Grid-Connected Control of Hydraulic Wind Turbine

The hydraulic wind turbine(HWT) is taken as the research object. To realize the quasi-synchronized safe connection of the HWT, the mathematical model of the fixed displacement pump - variable motor is first established, and the multiplicative nonlinearity existing in the modeling process is solved by the small signal linearization method. For the closed-loop speed regulation system of fixed displacement pump-variable motor, a variable speed input-constant speed output control method based on indirect flow feedback and direct-speed closed-loop system is proposed. Combining MATLAB/Simulink@ and a semi-physical simulation experiment platform of 30kVA HWT, the influence law of some parameters is analyzed for the response characteristics of the speed control system, such as the valve control cylinder response speed, the swash plate reference conversion value, initial swash plate angle and so on. At the same time, combined with the grid connection conditions for generators, a quasi-synchronized grid speed control method for HWT is proposed. Based on simulation and experimental methods, the instantaneous impact of grid connection is effectively suppressed.