Topological structure specific to low voltage ride through for doubly-fed type wind power generation system

The invention provides a topology specific to low voltage ride through for a doubly-fed type wind power generation system. By means of series connection of electric reactors on a rotor side converter and a rotor port, impedance of a rotor return circuit of the system is improved. Due to the fact that in a normal condition, the current frequency of the rotor return circuit is power frequency which is times of slip rate, the impedance of series connection of the electric reactors is not large, while during faults of a power grid, high voltage sensed by a stator direct current magnetic chain and a negative sequence magnetic chain is respectively close to the power frequency and two times of the power frequency. At the moment, the electric reactors in series connection under corresponding frequency have high impedance so as to effectively suppress large current during a fault period, enable the converter to keep operating during the fault period and meet the requirement for lower voltage ride through.