High-sensitivity stator fault protection for synchronous generators: A time-domain approach based on mathematical morphology

• Published in: International journal of electrical power & energy systems 2018-07, Vol.99, p.419-425
• Main Authors: de Morais, Adriano P., Bretas, Arturo S., Brahma, Sukumar, Cardoso, Ghendy
• Format: Article
• Language: English
• Subjects: Differential relay; Mathematical morphology; Stator faults protection; Synchronous generator
• ISSN: 0142-0615; 1879-3517
• DOI: 10.1016/j.ijepes.2018.01.038

•An analytical methodology for stator protection of synchronous generators is proposed.•A morphological filter is applied on the differential current providing real-time signal characterization.•Validation is done with OPAL-RT using a phase-domain synchronous machine model.•Only one protection function is able to detect all types of windings fault.•Single winding-ground fault close to the neutral end are detected even if the generators has high impedance grounding. This work presents an analytical methodology for synchronous generators stator faults protection. The proposed method is built on a differential protection relay strategy. A morphological filter is applied on the differential current providing real-time signal characterization. Unlike the traditional percentage differential relay, the proposed analytical methodology is able to detect all types of stator faults, including those close to the neutral end, which generates small differential currents due to the high impedance grounding of generator. Validation is done with OPAL-RT using a phase-domain synchronous machine model, which represents realistic operating conditions. The results of test cases highlights the method's dependability and security. Easy to implement models without hard-to-design parameters indicates the method’s potential for real-life applications.