Constrained by weak fault features on the rotor side

motor parameter mismatch after faults

and high-frequency harmonic coupling

inter-turn short - circuit faults in the rotor windings of offshore doubly fed induction generators(DFIGs) are hard to detect early. Existing methods have issues like low sensitivity to fault features and high misjudgment rates. This paper proposes an early fault identification method for rotor winding inter-turn short circuits of offshore DFIGs based on improved magnetic field oscillation technology. First

it reveals magnetic field changes before and after motor faults

clarifies the causes of magnetic field oscillation induced by faults

and proposes an improved magnetic field oscillation characteristic suitable for inter-turn short circuits in rotor windings. Then

this paper establishes a current residual model of the doubly fed motor in the fault state to expose the essence of the improved characteristic

and quantitative evaluation indexes for fault severity and fault phase location are proposed. Finally

simulations and experiments verify that the new magnetic field oscillation characteristics are robust to two common offshore operating conditions: slip rate variation and parameter mismatch. Analysis shows that the improved magnetic field oscillation characteristic is highly sensitive and reliable for early fault identification of DFIG rotor windings

solving the problem of extracting weak fault features of rotor inter-turn short circuits under strong interference and providing technical support for high-quality offshore wind power development.