A practical method to calculate short-circuit current in power system connected with doubly fed induction generators

Electromagnetic transient model of doubly fed induction generator (DFIG) during symmetrical short-circuit fault occurred in power system connected with DFIG and fault transient process of magnetic linkage in the stator and the rotor of DFIG are analyzed, and then the expression of short-circuit current in stator of DFIG under different stator voltage drop extents is derived and a method to correct the stator voltage drop coefficient, by which the calculation error of short-circuit current can be effectively reduced, is put forward. A practical method to calculate short-circuit current caused by symmetrical short-circuit fault occurred in power system connected with DFIGs is proposed. Taking the fault point as boundary point, the power system containing DFIG is simplified to an equivalent two-branch network composed of generator branch and system branch, then the operational curves of periodic components of short-circuit currents in generator branch and system branch are solved respectively to determine the amplitude of periodic components of short-circuit currents at the fault point, and expressions of aperiodic component and rotor frequency component of short circuit current at the fault point are derived.