The Study Of The Doubly-fed Induction Generators For Wind Turbines And Low Voltage Ride-through Technology

Wind power industry in China in recent years, the rapid development in interconnection of capacity in power grid increase gradually, the proportion of also increases year by year . Single fan capacity are constantly increasing 1MW development from the original 5MW 6MW fan to in June this year, the formal referral wind-power sinovelwind. Variable speed constant frequency grid way of substituting the traditional constant speed constant frequency grid, shifting constant frequency mainly includes two big mainstream models, namely doubly-fed induction wind generator and direct drive permanent magnet synchronous generator.This paper mainly on doubly-fed induction wind generators are described. Firstly expounds the rotor, mainly depends on the rotor absorption power wind, the wind energy coefficients and the radius of rotor. Wind energy utilization coefficient depends mainly on the rotor blade tip from Angle and speed. Secondly through mathematical model on doubly-fed generators are analyzed, and the vector control algorithm. Through testing the rotor d, q axis current constituted electric circuit.and the control. Through the torque and stator active power constitute power outer ring. Through testing the generator rotor d, q axis current vector control algorithm produces PWM pulse triggering the opening of two-way PWM converter. Doubly-fed generators the advantages are power factor adjustable or close to 1 current as sine wave. Finally through doubly-fed machine physical model built its simulation model, to verify its active, reactive power independent decoupling control.Based on the stator voltage which occurred fall doubly-fed machine transient performance analysis, in voltage dips process must on doubly-fed machine over-voltage over-current protection to. Otherwise, the meeting on doubly-fed machine and converter damage. Through the software and hardware method in the process of realizing the voltage drop across the success. In traditional based on rotor crowbar bypass resistance under the premise of insufficient, puts forward the new voltage across method. This method is superior to the traditional crowbar bypass circuit based on. Can quickly suppression and attenuation rotor over-current, without much increase hardware in the premise of GSC capacity, such as RSC and same, maximum reactive current injection quantity is the conventional 2 times. Doubly-fed generators physically and RSC from and not cause danger Over-voltage RSC.