Study On Strategy Of Resonant Suppression Of Doubly-fed Induction Generators Under Weak Gird

Wind power generation is one of the most rapidly developing renewable energy sources in the 21 st century.With the development of wind power,the wind power system based on doubly-fed induction generator is more and more used in the actual weak grid or distributed grid rather than the traditional strong grid.Because the impedance of the weak grid is much larger than that of the strong grid,the impedance of the doubly-fed wind power system may produce a resonance with that of the weak grid.Many experts have studied the subsynchronous oscillation between the series compensated weak grid and the doubly-fed induction generator,of course,there have been some recognized results.However,this paper mainly studies the problem of mid-high frequency resonance between the parallel compensated weak grid and the doubly-fed induction generator.In the first place,the mathematical model of doubly-fed motor is deduced in this paper.next in importance,the improved control strategy of the machine side of the doubly-fed motor is proposed,which is based on the voltage control scheme to control the machine side of the doubly-fed motor system more effectively.Then Then impedance modeling of the weak grid and doubly-fed wind power system provides theoretical basis for resonance generation and suppression of the following systems.Finally,the suppression strategy of quasi-resonant regulator is compared with that of active damping.At the same time,the effects of the cutoff frequency and virtual impedance parameters of the active damping suppression strategy on the suppression effect are studied.On the basis of theoretical analysis,the Matlab/Simulink simulation and experiment platform is built for the doubly-fed wind turbine under the weak grid,the generation of resonance and the improved suppression strategy are verified.The results show that the control strategy is effective and accurate.