Analysis on Steady-State Electromagnetic Characteristics and Online Monitoring Method of Stator Inter-Turn Short Circuit of Turbo-Generator

He, Yu‐Ling; Wang, Falin; Tang, Guiji; Ke, Meng-Qiang

doi:10.1080/15325008.2016.1247387

Cited by 15 publications

(8 citation statements)

References 16 publications

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“…When a short circuit occurs in the rotor or stator slot, the magnetic flux of air gap changes. The UMF results in radial vibration [48,49]. The reasons for short circuits include the unfixed excitation winding end, winding deformation, winding manufacturing defects and foreign matter intake, etc.…”

Section: Electromagnetic Sourcesmentioning

confidence: 99%

Review of Electromagnetic Vibration in Electrical Machines

Han

Chu

2018

Energies

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Electrical machines are important devices that convert electric energy into mechanical work and are widely used in industry and people's life. Undesired vibrations are harmful to their safe operation. Reviews from the viewpoint of fault diagnosis have been conducted, while summaries from the perspective of dynamics is rare. This review provides systematic research outlines of this field, which can help a majority of scholars grasp the ongoing progress and conduct further investigations. This review mainly generalizes publications in the past decades about the dynamics and vibration of electrical machines. First the sources of electromagnetic vibration in electrical machines are presented, which include mechanical and electromagnetic factors. Different types of air gap eccentricity are introduced and modeled. The analytical methods and numerical methods for calculating the electromagnetic force are summarized and explained in detail. The exact subdomain analysis, magnetic equivalent circuit, Maxwell stress tensor, winding function approach, conformal mapping method, virtual work principle and finite element analysis are presented. The effects of magnetic saturation, slot and pole combination and load are discussed. Then typical characteristics of electromagnetic vibration are illustrated. Finally, the experimental studies are summarized and the authors give their thoughts about the research trends.Energies 2018, 11, 1779 2 of 33 vibration mechanism can be helpful for the design of electrical machines. Therefore, the study of the electromagnetic vibration of electrical machines has practical significance.Electromagnetic vibrations are usually generated by the distorted air-gap field of an eccentric rotor in electrical machines. The uneven air-gap is directly related to the eccentricity, which is common in rotating electrical machines. Eccentricity can be caused by several reasons, such as relative misalignment of the rotor and stator in the fixing stage, misalignment of the load axis and rotor shaft, elliptical stator inner cross section, wrong placement or rubbing of ball bearings, mechanical resonance, and unbalanced loads [1,2]. Eccentricities can be further subdivided into two categories: circumferential unequal air gaps and axial unequal air gaps. The former can be grouped into static eccentricity and dynamic eccentricity. In the case of static eccentricity, the rotor rotates around its own geometric axis, which is not the geometric axis of the stator. In the case of dynamic eccentricity, the rotor is not concentric and rotates around the geometric axis of the stator. In reality, both static eccentricity and dynamic eccentricity tend to coexist. An inherent static eccentricity exists, even in newly manufactured machines, due to the build-up of tolerances during the manufacturing and assembly procedure, as has been reported in [3]. Unequal air gaps cause unbalanced magnetic forces (UMFs) [4] on the rotor, which lead to mechanical stress on some part of the shaft and bearing. After prolonged operation, these fac...

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Section: Electromagnetic Sourcesmentioning

confidence: 99%

Review of Electromagnetic Vibration in Electrical Machines

Han

Chu

2018

Energies

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“…e greater their values are, the more serious the fault will be. As indicated in (20), there is only a DC component in normal condition. However, the occurrence of SAGE will bring in extra 2nd harmonic to EMT, while SISC will primarily induce the 2nd and 4th harmonics.…”

Section: Emts In Different Running Conditionsmentioning

confidence: 99%

“…In this paper, we employ the principle of virtual power to derivate the EMT expression. e air-gap magnetic energy can be calculated via [20] Stator Complexity…”

Section: Emts In Different Running Conditionsmentioning

confidence: 99%

“…In addition, Moon et al proposed a method that uses voltage and current residual components to diagnose the exact phase and the severity of SISC in permanent-magnet synchronous machine [16]. It is found that the occurrence of SISC will significantly impact on the zero-sequence current [17], the negative-sequence current [18], the whole stator current [19], the rotor current [20], and the electromagnetic torque [21].…”

Section: Introductionmentioning

confidence: 99%

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Impact of Single and Combined Faults Composed of Rotor Eccentricity and Stator Interturn Short Circuit on Electromagnetic Torque Ripples in Synchronous Generator

Zhang

Wang

et al. 2020

Complexity

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In order to comprehensively study and identify the electromagnetic torque (EMT) difference among the single static air-gap eccentricity (SAGE) fault, the single stator interturn short circuit fault (SISC), and the combined fault composed of these two, this article investigates the EMT ripple properties due to the mentioned three faults. Different from other studies, this paper considers not only the effect of the single fault types but also the impact of the single fault combinations on the EMT ripple characteristics. Detailed EMT expressions for each fault are firstly derived on the basis of the magnetic flux density (MFD) analysis. Then, finite element calculation and experimental study on a CS-5 prototype generator with two poles at 3000 rpm, which is specifically designed and manufactured ourselves, are carried out to validate the analysis result. It is found that the three faults will induce different ripple components in EMT. The combined faults have the most intensive impact sensitivity on the EMT ripples, while the single SAGE fault ranks the last in the impact effect.

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“…The generator is the key equipment for a power plant and needs timely and accurate monitoring and maintaining. Typically, after a long-term operation, generators may endure many electrical faults such as the rotor interturn short circuit (RISC) [1] and the stator interturn short circuit [2,3], as well as mechanical faults such as rotor eccentricity [4].…”

Section: Introductionmentioning

confidence: 99%

Hybrid Fault Diagnosis Method Based on Mechanical-Electrical Intersectional Characteristics for Generators

He¹,

Sun²

2018

Fault Detection and Diagnosis

Self Cite

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In this chapter, a new hybrid fault diagnosis method based on the mechanical-electrical intersectional characteristics for turbo-generators is proposed. Different from other studies, this method not only employs the rotor vibration characteristics but also uses the stator vibration features and the circulating current properties inside the parallel branches of the same phase. Detailed theoretical analysis, as well as the experimental verification study, is carried out to demonstrate the proposed method. It is shown that in the proposed criterion for the method, the combining faulty characteristics for the single rotor eccentricity fault, the single rotor interturn short circuit fault, and the composite fault composed of the rotor eccentricity and the rotor interturn short circuit are all unique. The running conditions can be accurately and quickly identified by the proposed method. The work proposed in this chapter offers a new thought for the condition monitoring and the fault diagnosis of generators.

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Analysis on Steady-State Electromagnetic Characteristics and Online Monitoring Method of Stator Inter-Turn Short Circuit of Turbo-Generator

Cited by 15 publications

References 16 publications

Review of Electromagnetic Vibration in Electrical Machines

Review of Electromagnetic Vibration in Electrical Machines

Impact of Single and Combined Faults Composed of Rotor Eccentricity and Stator Interturn Short Circuit on Electromagnetic Torque Ripples in Synchronous Generator

Hybrid Fault Diagnosis Method Based on Mechanical-Electrical Intersectional Characteristics for Generators

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