Research And Design Of The Grid-connected Test Power Supply Of Wind Turbine

As more and more wind power and is connected to a power grid, many countries require that the wind power system can continue connecting to network, keeping running and can provide reactive power to support the grid when grid fails. But in the practical research of wind power generation system, it is not possible to directly using the grid to generate fault state, so we need some special power to simulate the fault, to detect the wind power operation. In this paper, the test power supply device not only can output standard sine wave power grid voltage, but also can simulate the voltage sag, phase shift, three-phase unbalance and voltage harmonics, meetting the actual engineering requirements of wind turbine power supply.Firstly, the topology structure of grid connected test power supply is given.The rectifier circuit uses three-phase voltage source PWM rectifier to obtain the stable DC voltage; The inverter circuit uses three single-phase inverters to simulate each phase of the three-phase inverter in order to obtain a consistent output voltage with the reference voltage, and achieve the purpose of controlling simply and three-phase four-wire output.Secondly, the PWM rectifier and inverter modeling. The rectifier model uses direct current control in the synchronous dq coordinate system to obtain the stable DC voltage; The inverter model uses voltage loop proportional integral and current loop proportional instantaneous value of double closed loop control(PI-P control) to achieve the standard inverter AC voltage output. Aiming at the problem of static error in PI-P control, the inverter adopts voltage loop proportional resonance and current loop instantaneous value double closed loop control(PR-P control). Through the comparative analysis, PR-P control does better in solving the problem of static. In order to meet the output requirement of different frequencies of the test power supply, the control method of the software and hardware is adopted to control the inverter. The hardware filter circuit uses the LC filter with variable frequency, and the software control adopts the improved PR-P control strategy.Finally, the main parameters of the grid connected test power are optimized and calculated, and the simulation model of the grid connected power supply is set up. On the basis of verifying the control strategy, the 30 kW hardware in the loop simulation system of d SPACE is set up. The experimental results show that the proposed grid connected test power supply topology and the control strategy are verified to be correct.