Modeling And Research Of Direct-Drive Wind Power System During Low Voltage Ride Through

With the rapid growth of world energy demand, the development and utilization ofwind energy has become the focus of attention in recent years, the rising proportion ofwind power generation in the grid system, the interaction between wind power and powergrid has become the focus of the current study. Technical requirements of various countriesto develop a wind turbine grid, mainly including low voltage ride through capability,reactive power control and active power change rate control, low voltage ride throughcapability of the biggest challenges in the control technology of wind power generationsystem design, directly affect the use of wind turbines and grid security. China has issuedwind farms into the power system technical requirement, the wind turbine is able tomaintain grid not off-grid operation when voltage drop, the system has the ability of lowvoltage ride through. Therefore, the wind power system low voltage ride through capabilityhas practical significance.The research background of this article is1500kW direct drive synchronous windgenerator group, mainly on wind electric system in case of voltage drop dynamicperformance, analysis of different types of grid voltage and different depths drop of windpower system impact, low-voltage crossing of the model optimal design.First, to study the characteristics of the wind turbine and permanent magnetsynchronous generator and operation mechanism, setting up a direct-drive permanentmagnet wind turbine structure model, the paper studies the wind turbine model, themathematical model of permanent magnet synchronous generator and changing convertermodel, and the establishment of a low voltage across the impedance of the form-basedsimulation program, to build the entire low voltage ride through simulation system model.Secondly, the dual PWM converter system motor side converter and grid sideconverter control strategy. Wind energy utilization factor analysis of the principle ofmaximum wind energy capture of the wind power generation system, the generator rotor field oriented vector control theory, machine side rectifier zero d-axis current controlstrategy, the PWM network side of the network side of the double-loop control strategy ofthe inverter design and SVPWM simulation analysis.Low Voltage Ride Through takes simulation software to build a1500kW wind powersystem grid simulation model, respectively in case of no-load, small load and the load onthe power grid three-phase short-circuit and single-phase short-circuit low voltage ridethrough simulation. The results indicate that the direct-drive synchronous generator systemsimulation model can achieve LVRT test. Optimized for future models, as well asproviding a basis for improved experimental method.