Research On Stability Of Wind Power Generation Integrating Into Power System

The state’s support for the new energy power generation industry and the improvement of the UHV transmission network provide development opportunities for large-scale wind power grid connection,but at the same time,the high-permeability wind power grid connection brings severe challenges to the security and stability of the power system,which will directly affect the voltage stability and frequency stability of the power system.Therefore,the frequency and voltage stability of wind power grid-connection is still one of the important issues in many countries.Therefore,the stability research of wind power grid-connection in this paper has important practical significance.This paper firstly introduces the development status of wind power in China,the problems existing in wind power grid connection,and the influence of wind power grid connection on the frequency and voltage of power system.The research status of virtual synchronous generator for wind power integration,flywheel energy storage for wind power integration,and STATCOM for wind power integration are introduced.Secondly,the structure,basic principle and operation state of doubly-fed asynchronous wind turbine are introduced,and the mathematical models of doubly-fed asynchronous wind turbine in three coordinate systems are deduced,including voltage equation,flux equation,torque equation and generator motion equation of DFIG.The mathematical model and control strategy of DFIG grid side converter and rotor side converter are introduced.Then,the mathematical model of the virtual synchronous generator is established,the control strategy of the virtual synchronous generator is introduced,and it is introduced into the converter control of DFIG,so that the doubly fed asynchronous fan has the external characteristics similar to the synchronous generator,and has the ability to provide the moment of inertia and damping to the power grid.The structure,mathematical model and three working states of flywheel energy storage are introduced.A control strategy to enhance VSG virtual inertia based on flywheel energy storage is proposed.By detecting the change rate of angular velocity of VSG virtual rotor,the difference between the angular velocity of virtual rotor and the grid angular velocity,and the state of charge of flywheel energy storage,the virtual inertia can be adjusted adaptively.Through MATLAB/Simulink simulation,it is verified that the control strategy has good frequency support ability for wind power grid connection,and can improve the frequency stability of wind power grid connection.Finally,the principle of STATCOM is introduced,the mathematical model of STATCOM is established,and the PI control strategy of STATCOM is studied.The advantages of ADRC compared with PI control,and the structure and algorithm of first-order and second-order ADRC are introduced.A dual closed-loop STATCOM control strategy for ADRC is proposed.The first-order ADRC is used in the inner current loop,and the second-order ADRC is used in the outer voltage loop.The ADRC parameters are optimized by ant colony algorithm.Through MATLAB/Simulink simulation,it is verified that STATCOM of ADRC has good reactive power compensation effect and can improve the voltage stability of wind power grid connection.