# Detection, Discrimination, and Localization of Rotor Winding Faults in Doubly Fed Induction Generators Using a Three-Layer ZSC–CASI–CADI Framework

## TL;DR

This paper introduces a new framework for detecting and diagnosing faults in wind turbine generators to improve system reliability.

## Contribution

A novel three-layer framework (ZSC-CASI-CADI) is proposed for accurate rotor winding fault detection and localization in DFIG systems.

## Key findings

- The framework successfully discriminates between HRC and ITSC faults using rotor current phasor dispersion.
- Fault localization is achieved through angular deviations in rotor currents from the zero-sequence current reference.
- Simulation results confirm accurate real-time diagnosis under various load and speed conditions.

## Abstract

Reliable detection of the rotor winding faults in the doubly fed induction generator (DFIG) is crucial for the resilience of the variable speed energy systems. High-resistance connection (HRC) and inter-turn short circuit (ITSC) faults cause current distortions that are remarkably similar, and the rapid rotor side dynamics and the DFIG multimode operation ability also make fault diagnosis more difficult. This paper proposes a three-layer diagnostic framework named ZSC-CASI-CADI which leverages three-phase rotor currents in conjunction with rotor zero-sequence current (ZSC) for comprehensive rotor winding fault diagnosis. Fault detection is realized through ZSC magnitude and the Cosine Angle Spread Indicator (CASI) enables the strong discrimination between HRC and ITSC faults using the dispersion of rotor current phasors from the ZSC reference. Fault localization is achieved using the Current Angle Difference Indicator (CADI), which determines the faulty rotor phase through the angular deviations in rotor currents from the ZSC. The methodology is verified with extensive simulation results to demonstrate the accurate, real-time fault detection, discrimination, and localization of DFIG rotor winding faults under different load and rotor speed conditions including sub-synchronous and super-synchronous modes. The results show that the proposed framework provides a light and effective solution for rotor winding fault monitoring of the DFIG systems.