Closed loop bandwidth impact on doubly fed induction machine asymmetries detection based on rotor voltage signature analysis

This paper investigates the impact of the control system bandwidth on the detection of incipient faults in doubly fed induction generators used in wind turbines. In this application, the rotor is supplied by a static converter for the control of active and reactive power flows from the generator to the electrical grid. The Impact of the closed loop control system cannot be neglected when the detection of asymmetries in the machine are based on the signature analysis of electrical variables. An investigation of the behavior of faulty spectral components for different bandwidths of closed loop regulators is therefore necessary in order to evaluate the effectiveness of diagnostic indexes based on those variables. Simulation and experimental results are here presented to show the limits of two different approaches for fault detection. The first one based on current signature analysis and the second one based on rotor voltage signature analysis.