Research On Static Voltage Stability Of Wind Power Integrated With Power Grid

Wind farms Wind farms in wind power grid-connected systems are located within the distribution network,far from the load center.It belongs to a two-side stochastic system.Its randomness and unpredictability lead to outstanding stability of the system,especially the problem of voltage stability is prominent.In severe cases,it will cause irreversible consequences such as the distribution network disassembly.Therefore,it is of great theoretical and practical significance to study the static voltage stability of wind power grid connected system.Therefore,it is of great theoretical and practical significance to study the static voltage stability of wind power grid connected system.In this paper,based on the analysis of voltage characteristics of double-fed wind power grid-connected system,according to power flow calculation and PV curve power flow analysis method,the static voltage stability criterion based on power flow solution is deduced,and Voltage-active sensitivity margin indicator based on comprehensive parameters is deduced.We have proposed the necessary and sufficient conditions for static voltage stabilization of wind power grid-connected systems.On this basis,in order to effectively suppress the 3rd harmonic component of 3,SVC is proposed to connect the grid-connected system with delta connection.Finally,aiming at the errors caused by different voltage points and compensation points of the system,the traditional SVC reactive power compensation strategy is improved,and inner loop admittance negative feedback control is proposed.The main research contents of this article are as follows:(1)Establish the mathematical model of doubly fed induction generator system.Based on the analysis of the operation mechanism and characteristics of the doubly-fed asynchronous wind turbine,a simulation model of a 6×1.5MW double-fed wind power system was established in the Matlab/Simulink platform.Analyze the external characteristics of the outp.u.t voltage of the system,and finally conclude that the fluctuation of the external wind speed will cause the outlet voltage of the wind farm to fluctuate.these lay the foundation for the follow-up study.(2)Based on the static mathematical model of the doubly fed wind turbine,according to the static voltage stability,we use the PV curve flow analysis method.According to the power flow calculation of wind power grid connected system,the static voltage criterion L based on the power flow solution and the static voltage stability margin Kp based on the comprehensive parameters of voltage active power are derived;Based on these,a sufficient and necessary condition for the stability of the system's static voltage is studied: Kp>0 & L?1,and the experiment verifies its correctness.(3)According to the necessary and sufficient conditions of the static voltage stability,the reactive power sensitivity relationship with the grid point is analyzed;We use the most typical TCR+TSC type dynamic Static Var Compensator(SVC)to perform reactive power compensation on wind power grid-connected systems.Taking TCR+TSC type SVC as the research object,based on the load sensitivity index of static stability margin.On this basis,in order to effectively suppress the generation of high-order harmonic components of the SVC,which is a multiple of 3 times,a TCR+TSC-type SVC based on a delta wiring method is proposed;In order to improve the system's anti-disturbance and control accuracy,and realize the system-free voltage control,a TCR+TSC-type SVC control strategy based on admittance and negative feedback of the inner loop is proposed.The experimental results verify the effectiveness of the proposed method.