Fault isolation based in Structural Analysis and EWMA of the set DFIG/Back-to-Back converter of a Wind Energy Conversion System

This paper proposes a fault isolation system for the set Double Feed Induction Generator (DFIG)/Back-to-Back converter of an off-grid Wind Energy Conversion System (WECS). An a priori task is the fault diagnosability analysis of the system by means of Structural Analysis (SA), from which the redundant information is extracted - analytical redundant relations (ARR's). The residual generators for the isolation system make use of the ARR's and the explicit analytical equations of the system. Given that the system is based on a power electronic converter, the input signals to the residual generators are switched signals, which yield a bad performance of the ARR's. In order to enhance the performance and sensitivity of residuals under faulty conditions, an exponentially weighted moving average (EWMA) strategy is used on the raw residuals obtained from the ARR's. 26 faults are considered in the diagnosability analysis same which are tested on a WECS simulator created on Simulink/MatLab.