Studies on the LVRT Capability of Integrating DFIG

This paper presents a detailed analysis of the low voltage ride-through(LVRT)functions of the doubly-fed induction generator(DFIG).The model and control strategy of the doubly-fed induction generator with LVRT are established on the power system simulation tool PSASP.The geographic wiring diagram used intuitively indicates the impacts on the terminal voltages of wind turbine generators at the moment when a short circuit takes place in the power grid.And taking a regional power grid as an example,analysis is made on the impact of the short circuit happened in the external power grid under different patterns of connecting with the wind farm,and based on the simulation result,and the minimum voltage limit of LVRT of wind turbines is given.Finally,the paper introduces a new method to increase the LVRT of wind turbines by means of series dynamic braking resistors.Analysis results show that the series dynamic braking resistors can considerably increase the LVRT of wind turbines.Wind turbines of higher LVRT capability help reduce the investment costs,and to a certain extent,give rise to a reduction of the wind power electricity price.