The Research On The Low Voltage Ride Through Of Permanent Magnet Direct Drive Wind Turbine

With the rapid development of the global industry, energycons-umption is increasing, and environmental pollution is more andmore serious. As a kind of renewable energy, wind is one of the mostpromising energy and has been rapid development in recent years. Theproportion of wind is increasing in the power supply, when power grid isfault, if the wind turbine can not work in the stability of the state,Cascading failure will be caused in the power grid. As a result, to ensurethe security and stability of the power grid, the low-voltage ridingthrough must be studied in following study. In this paper,2MWpermanent magnet direct drive wind turbine is simulated inMatlab/Simulink by considering the normal conditions and faultconditions of the voltage drop, and the simulation results are comparedand analyzed by comparing the field test data to demonstrate theoreticalfeasibility of the model operating conditions. This paper completes theworks as following:(1) In order to simulate the grid voltage drop fault so that the voltagedrop operated simply and convenient transportation, the voltage dropsimulation device of transformer type is designed. According to thestructural characteristics of the permanent marine direct-drive windturbine, the converter control strategy is established based on thevoltage-oriented vector control, the active and reactive power control areapplied in machine side/network side, simulation/experimental programthat Crowbar (unloading discharge energy)protects the wind turbinecrossing low voltage is applied to the DC bus.(2) According to the design scheme, the mathematical model of directdrive permanent magnet wind turbine is established, including themathematical model of wind power generator, the direct drive permanentmagnet wind turbine, the machine side converter and the grid sideconverter, and a simulation model of all unit are built in the software ofMatlab/Simulink. Meanwhile, a type of transformer of voltage droppingdevice and DC bus energy release device——Crowbar are also built, andit gives the basis of parameters setting of the whole control system. Eventually, it established the control strategy of direct drive permanentmagnet wind turbine under the normal operating conditions and lowvoltage ride through.(3)The simulation analyze of low voltage ride through is done aboutthe entire generator, and is compared with the actual data of the windfarm. The scheme is verified to be feasible and the model is verified to becorrect.The experimental results show that the design can maintain thestability of power grid voltage, to some extent, when the fault is causedabout the power grid voltage in the paper. It indicates that the windturbine can regulate the power grid voltage and ensure the safety andstability of the whole power grid by adding the converter.