Online condition monitoring of large synchronous generator under short circuit fault — A review

2020 International Conference on Electrical Machines (ICEM)

Groth

et al. 2020

The excitation windings of the synchronous generators are generally reliable. However, electrical, mechanical, and thermal stresses that the machine is exposed to during its operation leads to the inter-turn and ground insulation faults. On-line condition monitoring could provide a valuable real-time assessment of the synchronous generator. It could discriminate gradual aggravating defects at an incipient stage before it leads to irreversible and costly damages. On-line monitoring of the air gap magnetic field has been used in different types of electrical machines. However, some concerns should be considered when applying this method to the salient pole synchronous generators (SPSG), especially in the SPSG, with a large number of turns per poles that show less or lack of sensitivity to a fault. This difficulty could be solved by wise locating of the Hall effect sensor, choosing precise sampling rate, re-sampling the data and signal processing approach. In this paper, detailed online monitoring of the air gap magnetic field under the excitation winding defect is proposed. A procedure that could detect the severity and location of the fault-based on different analyzing methods of flux density in no-load and full load is proposed. The nominated approach is examined by using numerical modeling and a experimental test rig with a 100 kVA SPSG. It is proven that the air gap magnetic field spectrum could provide a reliable assessment of the machine under the short circuit fault of the rotor field winding.

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Section: Introductionmentioning

confidence: 99%

Detailed Magnetic Field Monitoring of Short Circuit Defects of Excitation Winding in Hydro-generator

2020 International Conference on Electrical Machines (ICEM)

Groth

et al. 2020

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“…The ITSC fault can occur due to electrical or mechanical problems in the field winding insulation. ITSC failure can give rise to local hot spot and vibrations that in turn can accelerate the insulation degradation [1]. Numerous approaches are proposed to detect the fault in synchronous machines which mostly relys on harmonic analysis of the stator terminal voltage [2], air gap magnetic field [3], phase currents [4], and vibrations in the frame [5].…”

Section: Introductionmentioning

confidence: 99%

Pattern Recognition of Inter-Turn Short Circuit Fault in Wound Field Synchronous Generator via Stray Flux Monitoring

2020 International Conference on Electrical Machines (ICEM)

Nilssen

2020

This paper provides a novel approach to discriminate the Inter-Turn Short Circuit fault (ITSC) in salient pole synchronous generator based on the use of non-invasive sensors. A stray magnetic field is used as a non-invasive signal that could provide valuable data regarding the condition of the synchronous machine. The captured signal under different severity of the ITSC fault is examined by using a classical signal processing tool based on Fast Fourier Transform. A unique feature based on extracted sub harmonics from the stray magnetic field is used to demonstrate the sensitivity of the signal to fault severity increment. It has been shown that the nominated feature do not have any sensitivity to the load variation. The theoretical hypothesis which is supported by using finite element method analysis is tested and verified by experimental results.

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“…The demagnetization of permanent magnets is also classified as a magnetic fault in permanent magnetic machines. Each kind of failure could give rise to a specific symptom in the electrical machine, which may be observed in a measured signal [1].…”

Section: Introductionmentioning

confidence: 99%

The Noise Effects on Signal Processors Used for Fault Detection Purpose

Skreien

2020 23rd International Conference on Electrical Machines and Systems (ICEMS)

et al. 2020

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