Research On Rotor Inter-turn Short Circuit Fault Of Doubly-fed Wind Power Generators

In recent years, doubly fed induction generators(DFIG) become mainstream models among wind farms base on its flexibility characteristics to achieve VSCF. Rotor windings inter turn short circuit fault is one of the common fault of DFIG, it would increase the pressure of control system, while failure would continue to deteriorate, and even develop into an accident, if the inter turn short fault were not be maintenance timely. Both to reduce misdiagnosis and improve diagnostic accuracy, but also to provide a simple, accurate fault location method for rotor windings inter turn fault is significant to operate and safeguard a wind farm. Main work done shown as follows:(1) Simulation model was built in Ansoft based on the electromagnetic coupling and finite element theory. The simulation model is closer to reality by different design of the model itself and external circuit, and then rotor windings inter turn fault, rotor windings inherent imbalance and eccentric rotor are simulated.(2) The impact of rotor windings inherent imbalance on rotor windings inter turn short circuit fault feature has been studied. Consider the fact that rotor windings can not be completely symmetrical(ie rotor winding inherent imbalance exists), the impact of rotor windings inherent imbalance on rotor windings inter turn short circuit fault has been studied. And distinguish them from each other by spectral characteristics of rotor line current and stator line voltage. Then avoid misdiagnosis of rotor windings inter turn short fault by inherent imbalance.(3) The impact of eccentric rotor on rotor windings inter turn short circuit fault feature has been studied. Eccentric rotor is considered when the simulation model is built. Eccentric rotor and rotor windings inter turn short is distinguish from the other by spectral characteristics of rotor line current and stator line voltage. Then avoid misdiagnosis of rotor windings inter turn short fault by eccentric rotor.(4) A new fault location method is offered for rotor windings inter turn short fault. This paper offers a new fault location method by improving the detection coil and using photovoltaic device. When the rotor windings inter turn short fault occurs, it could make an accurate positioning for the fault without resolving the generator.