Research On Reclosing Strategy Of Distribution Network Containing Wind Farm

At present,China is in the transition stage of green and low-carbon energy,in which wind power generation is an important part of new energy.However,as the capacity of grid-connected wind farms increases,the operation characteristics of the traditional power system are changed,and the relay protection and automatic reclosing of the traditional power grid are presented with new challenges.Therefore,it is necessary to study the fault characteristics and reclosing strategies of distribution network containing wind farm,and put forward reclosing strategy suitable for distribution network containing wind farm.First,the mathematical model and operation control strategy of the doubly-fed induction wind turbine under different operating conditions are analyzed.In MATLAB/Simulink simulation software,the equivalence model of wind farm access to distribution network is built,and the correctness of equivalence model in normal steady state and fault state is verified by simulation.Then,the influence of initial power flow on dynamic voltage and frequency of isolated island system is studied.Combined with the standard of reclosing of conventional double-end power line,the reason why the checking same-period criterion is not applicable to the reclosing of the wind farm is analyzed,and quasi-synchronization criterion for reclosing of wind farm is proposed.The feasibility of wind farm reclosing using quasi-synchronization criterion is verified by simulation.Finally,the impact of low voltage ride-through and islanding protection on reclosing in the distribution network is studied,and a line reclosing strategy suitable for wind farms connected to the distribution network is proposed.This strategy is based on the deep neural network model to calculate the nonlinear relationship between the outlet voltage and frequency of the wind farm and the initial power flow of the tie line.The voltage amplitude and phase angle at the reclosing of wind farm and the initial power flow of the tie line are used as input characteristics to predict the outlet voltage and frequency value of wind farm.The predicted value is compared with the anti-islanding protection value,and the appropriate reclosing criterion is selected according to the operating conditions of the wind farm.If the wind farm is off the grid,the wind farm reclosing will adopt the criterion of the detection line with voltage bus without voltage.If the wind farm is in operation,the wind farm reclosing will adopt the quasi-synchronization criterion.This strategy solves the logical contradiction between low voltage ride-through,anti-islanding protection and reclosing action time of wind farms,and improves the success rate of reclosing actions for lines connecting wind farms to the distribution network.