(State Key Laboratory of Advanced Electromagnetic Engineering and Technology, (Huazhong University of Science and Technology), Wuhan 430074, China)

An incorporation of a Crowbar is still the main method for the doubly-fed induction generator (DFIG) in low-voltage ride through. Generally, the mutual coupling between the stator and rotor flux is ignored during the transient analysis of DFIG with Crowbars, but this approximation has brought about obvious errors and even left out some transient characteristics. Through an analysis of the process of low voltage ride through (LVRT) based on a detailed model of DFIG, accurate expressions for stator flux, stator current and rotor current are deduced. Thus the characteristic of these variables are analyzed and the values calculated. An actual 10 kW DFIG iss used for case study, the simulation results proving the accuracy of the expressions. From these formulas, the relations between the values of Crowbar resistors and the pulsation amplitude of electromagnetic torque, output power are revealed. Taking into account the DC-link clamp effect and influence on the performance of DFIG during LVRT, a new Crowbar resistance design method is proposed for reference in relevant engineering projects. This work is supported by National Basic Research Program of China (973 Program) (No. 2012CB215100)， National Natural Science Foundation of China (No. 51477064) and Lite-on Power Electronics Technology Research Fund (No. 2013-04).