Grid Fault Performance of Brushless Doubly-Fed Reluctance Machines in Wind Turbine Applications

The DFIG and the BDFRM have very similar dynamic equations, however the BDFRM's complex flux coupling produces machine parameters very different to the DFIG. These parameter differences result in different intrinsic machine behaviour under fault conditions. This paper develops and uses a simple model to explain the fault performance differences between the machines, and then verifies these predictions using a combination of simulation and experimental results. The general conclusion is that the intrinsic large leakage inductances of the BDFRM assist with protecting the rotor side converter during grid side fault conditions.