Study On The Low Voltage Ride Through Technology Of Doubly-Fed Wind Power Generation System

In the context of conventional fossil energy greatly consumption and increasingly severe environmental pollution, making well use and development of alternative clean energy has become the inevitable choice issues and to solve the energy and environment problems. Because wind energy is renewable and pollution-free, wind farm construction period is short and operation cost is low, wind power has become the most mature and the largest commercial development power generation in new energy generation technology.With increasing proportion of wind turbine capacity in the power system, the interaction between the grid and Wind turbine become more significant, especially when the grid has voltage dips, it is required that grid-connected wind turbine has low-voltage operation capability. Currently, countries around the world have developed a wind power system operating criteria at low voltage. In this paper, 1.5MW double-fed wind power generation system is the research object, and the theoretical study for both generator-side and grid-side converter as well as Low Voltage Ride Through technology (LVRT) were carried out.Firstly, on the base of operating principle of Doubly-fed Induction Generator (DFIG), the mathematical model of DFIG was established and the vector control strategy based on stator flux oriented was studied. Secondly, the mathematical model and equivalent circuit of grid-side converter have been established, and mainly carried out the grid voltage oriented vector control strategy and Space Vector Pulse Width Modulation (SVPWM), and then the paper verified the control strategy of generator-side and grid-side converter by Matlab/Simulink software. Finally, this paper analyzed the dynamic response of DFIG wind power system at low voltage, introduced the most commonly used Crowbar protection circuit of generator-side and DC side protection circuit, and determined a combination protection circuit and studied it's control strategy. By simulation, the dynamic response of DFIG,protection circuit and control strategy at low voltage have been validated.