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.