Study On Low Voltage Ride Through Of Double-fed Induction Generator Wind Turbine

Currently, due to the increase in world population and economic growth andother factors led to the rising demand for energy and the rising of public awarenessfor environment protection, renewable energy has been the rapid development andwind power has also attached great importance to the world. With the dramaticincrease of wind power penetration, the impact of wind power on the grid stabilityregion can not be ignored. Doubly-fed induction generator wind turbine (DFIG-WT)has become mainstream with its wide speed range, adjusted independently activeand reactive power and smaller excitation current transformer capacity. DFIG afterback-to-back full power converter is connected with power grid. when the gridvoltage drops, wind turbine off-grid operation will exert serious impact on thestability of the grid. This dissertation focuses on research work on how to improvethe low-voltage operation capability of direct-drive permanent magnet windturbines.In this paper, Variable speed constant frequency(VSCF) doubly fed inductiongenerator is the object of study. Firstly, an analysis of the structure and the operationprinciple of DFIG model and the grid side converter grid voltage vector orientedcontrol strategy are proposed. Secondly, for three-phase short circuit fault occursgrid when voltage drops sharply doubly-fed induction motor electromagnetictransient analysis, given the generator rotor to produce over-voltage andover-current reasons. Thirdly, by analyzing the topology of the circuit andshort-circuit fault Crowbar suppression performance, the use of the principle ofconservation of energy derived tuning method of Crowbar resistor. A simulationanalysis verifies the optimizing of low voltage ride through(LVRT) the Crowbarcircuit resistance selection and switching time. Finally, according to the networkafter grid side converter of different operation modes to determine the grid side converter LVRT control methods. Proposes the LVRT coordinated control strategycombining with the Crowbar protection, and verifies its feasibility by simulation.