Segmentation control method for low-voltage ride-through of doubly-fed motor during symmetric drop of network voltage

The present invention discloses a method of controlling segmentation doubly-fed machine when one kind of low voltage ride through grid voltage drop symmetric, comprising a rotor detect current and DC bus voltage; real-time detection of the rotor current and the instantaneous value of the DC bus voltage and a respective upper limit value comparing the comparison result of the determination logic circuit in accordance with a control signal crowbar, if one rotor current or a DC bus voltage which exceeds the limit, then the output logic control signal is high, i.e., the control start stage ⅰ; crowbar protection after starting, continues to detect the DC bus voltage and the rotor current, and then compared with the respective lower limit value, when the bus voltage and the rotor current is less than the respective lower limits of the output logic control signal is low, Crowbar circuit out of operation, the recovery field control, a first control stage ⅱ. The present invention can be effectively achieved through the fault of the doubly-fed machine, while injection demagnetization current and reactive current to the grid, to shorten the time crowbar protection.