Subsynchronous Oscillation Analysis And Suppression Of Doubly-fed Wind Power Generation System

With the continuous expansion of renewable energy power generation capacity,the grid's wind power penetration rate has gradually increased,and rese arch on the integration of wind power and power grids has received increasing attention.In the course of the transmission of electric energy from a doubly-fed wind generator(DFIG)to the grid,long-distance transmission and series compensation capacitors induce subsynchronous oscillations in the DFIG unit of the wind farm,which limits the increase of wind power penetration and affects the stable operation of the system.Under this background,it is of great theoretical significance and practical value to study the corresponding subsynchronous oscillation suppression strategy and improve the anti-interference ability of subsynchronous voltage of DFIG wind power system.This paper firstly established the mathematical model of the doubly-fed motor,and discusses the double fed chance of power flow in different conditions.Then I set up the mathematical model of the network side converter(GSC)and its control strategy and the dynamic and static characteristics are discussed in this paper,put forward the voltage current double closed loop PI control scheme.Then through the rotor side converter(RSC)control of the doubly-fed motor rotor current loop vector control system is designed,which will be successfully control doubly-fed motor active reactive power decoupling.Then use the simulation of Matlab/Simulink verified the rationality of the proposed control scheme.Then this paper analyzes the causes of subsynchronous oscillation wind power system,points out that the transmission line series compensation cap acitor causes a subsynchronous oscillation of the doubly-fed wind power system,and according to the different object switch synchronous oscillation can be divided into subsynchronous resonance(SSO),time synchronization torque interaction(SSTI),time synchronization control interaction(SSCI)three categories.Of SSCI oscillation process are discussed in this paper,it is concluded that SSCI oscillation divergent conditions.Then the subsynchronous oscillation occurred the defects of the traditional phase-locked way are discussed and put forward based on double second-order generalized integrator software phase-locked control technology,the phase-locked control under subsynchronous harmonics power grid for the Matlab/Simulink simulation and experimental validation.Putting forward by the RSC directly suppresses the output of the generator stator subsynchronous resonance control current and inhibition of dc bus through the loops of GSC resonance and reactive power of time synchronization pulse suppression scheme,and comparative analysis harmonic proportion coefficient and the cut-off frequency of current loop dynamic response speed and the influence of the anti-interference ability of time synchronization voltage.Finally,about the frequency of the resonant controller adaptive subsynchronous oscillation suppression strategy based on harmonic current extraction,through high-pass filter the first synchronization in synchronous rotating coordinate system harmonic current extracted and added to the current loop in order to inhibit the time synchronization of the stator current,and the response speed and dynamic response inhibition effect were discussed.at last,the effectiveness of the above related subsynchronous oscillation control strategy is verified by Matlab/Simulink simulation and experiments.