Influence Of High Penetration Wind Power Integration On Power System Stability

Wind power integration will lead to changes in system stability,the current wind power penetration is still at a low level,with the wind power development,wind power penetration continues to increase,in the case of high penetration,the regional power grid stability may be different from the current low penetration situation.In this dissertation,the model of Fix Speed Induction Generators(FSIG)and Doubly-Fed Induction Generator(DFIG)is established,and a method for establishing dynamic equivalent model of FSIG-based wind farm and DFIG-based wind farm is proposed.Based on the dynamic equivalent model of wind farm,influence of high penetration wind power integration on power system angle stability and small signal stability is studied.Finally,the method of improving the damping characteristics in the power system and the method of improving the small signal stability in the microgrid are studied.The main research results are as follows:1)The mathematical model of two wind turbines is established,which includes: DFIG model and FSIG model.The typical characteristics of the FSIG in steady state and transient state are analyzed,as well as the typical characteristics of the DFIG in dynamic state and transient state.2)A method is proposed for establishing the dynamic equivalent model of DFIG-based wind farm.The method uses wind speed as the grouping index of DFIG,uses the improved max-min distance means based on spectral clustering algorithm to cluster the wind farm.The clustering algorithm can determine the number of the most appropriate clustering of wind farm automatically and avoid the shortcomings of the traditional clustering algorithm that needs to set the number of groups before the calculation,at the same time,the capacity-weighted parameter polymerization method is applied to the parameter polymerization of the wind farm equivalent model,in the parameter polymerization of the converter controller,the tedious adjustment of the control parameters is avoided by changing the input signal.This method is also applicable to the dynamic equivalent model of FSIG-based wind farm,except that the grouping index is different.3)Base on the equivalent external characteristics of DFIG during the period of the fault and the power characteristic equation of single-terminal delivery system,the effect of different scale wind power on the electrical distance between the sending power grid and the receiving end power grid is studied,and the influence mechanism of different scale wind power integration on power system angle transient stability under different fault conditions is researched.Through the derivation,the optimal wind power output in multi-machine system to make the system angle stability best is found.4)The influence of the ways to increase the penetration of wind power on power system damping ratio is studied in this paper.The influence mechanism of rotating reserve capacity on small signal stability is deduced and analyzed,based on this mechanism,the reason for the different variation of the system damping ratio is explained in the case of reducing output of power units to increase wind power penetration.The influence mechanism of DFIG instead of thermal power unit on small signal stability is deduced and analyzed,based on this mechanism,the reason for declining of system damping ratio is explained in the case of exiting operation of power units to improve the penetration of wind power.5)Two methods of improving the damping characteristics of large power grid and the small signal stability of microgrid are studied.In the large power grid,the principle of DFIG active power and reactive power additional damping control strategy improving system damping is analyzed,based on this principle,a design method of additional damping controller for DFIG is proposed.In the microgrid,a coordinated tuning method is proposed to set the parameters of distributed generation controllers based on the root locus algorithm and particle swarm optimization.In this method,the real part of the main eigenvalue is minimized as the objective function,and use the root locus method to determine the parameters,which is used as the initial value of the particle swarm optimization algorithm.