Large-scale Wind Turbine Chain Network Failure Defense Strategy Research

High-density centralized access and distributed access of large-scale wind turbines pose great challenges to the safe and stable operation of power grids.The wind power has the characteristics of random power fluctuation,the power fluctuation range is large,the conventional power supply is difficult to follow the power fluctuation of the wind power generation,the system frequency and voltage problems are prominent,and the operation and control of the power grid greatly affect.The cascading tripping-off of wind turbines will not only limit the acceptance ability of wind power,but also seriously threat the safe and stable operation of power system.In recent years,large-scale wind power chain off accidents have occurred,has attracted widespread attention of scholars at home and abroad.In view of the frequent occurrence of large-scale wind power network interlocking accidents,this paper first briefly describes the reasons for the large-scale wind farm substation network problems and analyzes the main factors that affect the wind power plant interlocking network problems.Starting from the two stages of low-voltage off-line and high-voltage off-grid,the research on the development process and mechanism of chain-off accidents of wind turbine generators is researched.Subsequently,two doubly-fed wind turbine units were built by PSCAD / EMTDC simulation software to simulate the high-voltage wind-out and low-voltage wind-out of wind turbine.After that,this paper applies the search mode of power system chain fault to the chain-off process of large-scale wind turbines,brings out the concept of network-off path,and makes a modeling analysis of the chain-off path of wind farm.Accident risk assessment system.Then,by the simulation analysis of some wind farm stations in the Northwest Power Grid,the correctness of the proposed method for detecting the off-grid path is verified.Finally,this paper proposes a hierarchical control strategy,namely,a preventivecontrol strategy and an emergency control strategy,aiming at blocking the transmission path of the off-net path,and reducing the length and severity of the off-network path,and gives the data layer and the decision layer.The implementation of the three levels to block and control the strategic structure of the off-net path.Finally,a practical application case is used to prove the effectiveness of the strategy.