Research On High Voltage Ride Through Ability Of Doubly-Fed Wind Turbine And Its Application

With the rapid development of wind power technology,especially with the application of a large number of cutting-edge technologies in Doubly-fed wind turbine,the wind turbine capacity and it’s system control complexity have gradually upgraded.The Doubly-fed wind turbine have become the main force in the wind power generation market.Due to the increasing proportion of wind power generation to the total grid capacity,if the grid-connected wind farm does not have the ability to grid fault ride through.Under the power grid fault,it will many wind farms offline if the wind farm failure to provide frequency and voltage support to the power grid,endangering the operation of the power grid.In order to maintain the safe and reliable operation of the power grid,the study of wind turbines in the Grid Fault Ride Through has become an important research direction,especially the Low Voltage Ride Through,High Voltage Ride Through,primary frequency control and so on.This paper focuses on High Voltage Ride Through.Taking the WT1650 Doubly-fed wind turbine,as the research object,this paper analyzes the system structure of the Doubly-fed wind turbine,establishes the hub system model,the transmission system model,the pitch control system model and the mathematical model of the asynchronous generator and excitation converter in the dq coordinate system.Among them,the grid side part of the converter adopts the vector control strategy based on grid voltage orientation,and the rotor part adopts the vector control strategy based on the stator flux oriented.On the basis of establishing the model,the influence of power grid surge on asynchronous generator,pitch control system and excitation converter is analyzed deeply,and the technical scheme of double-fed wind generator HVRT is designed according to the influence range of the analysis.The control strategy of converter,pitch control system and main control system is optimized,and some hardware of the hardware is upgraded.Finally,the HVRT control strategy designed in this paper is tested in the Laolongkou wind farm according to the requirements of the “The test regulation for High Voltage Ride Through Capability of wind turbine".There are 16 tests are designed according to the requirements of the regulation.The field test results are is analyzed one by one.Through the coordinated control of excitation converter,pitch control system and main control system,the voltage fluctuation of DC bus and the output active power fluctuation of the wind turbine are effectively reduced,and the load of braking chopper circuit and crowbar circuit are reduced.the reactive power output response time of rotor side converter is improved at the same time.The field test results showthat the HVRT strategy designed in this paper has excellent performance in grid fault ride through capability.