The research of zero voltage ride through strategy of DFIG

摘要

With the increase of wind power capacity in the grid, the running characteristics of wind turbines in the grid should not be ignored, especially the fault ride through ability of the wind turbines make a great influence to the safety of power grid. In this paper, the double fed wind generator (DFIG) with the Crowbar protection strategy is the main research object, a detailed studied is given on the change of transient characteristics and adaptability of the existing protection strategy when the terminal voltage of wind turbines dropped to 0pu. On this basis, the comprehensive control strategy of zero voltage ride through (ZVRT) of DFIG is put forward — a comprehensive control strategy with rapid pitch angle control, multiple levels of protection circuit response and the improved excitation control strategy. Through simulation comparison, it confirmed that the new comprehensive ZVRT control strategy could effectively suppress the fault current in the rotor and stator of DFIG, reduce the oscillation of torque and inhibit the rotate speed rise of rotor in the ZVRT, it is very help to enhance fault ride through ability of DFIG.