Analysis and Testing of Negative Sequence Heating of Turbine Generator Rotors

Salon,; Shah, Mubarak; Montogomery,

doi:10.1109/mper.1981.5511786

Cited by 4 publications

(5 citation statements)

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“…As an example the calculation values are valid for a spot whilst the measuring sensor averages the signal over a certain area due to its finite extensions. Generally, the results comply with some published results [4]. In the end, the calculation and measuring results prove each other so that we can use them for proving the conclusions in section II that the negative sequence current can submerge cross slits.…”

Section: A Comparison Of Resultssupporting

confidence: 85%

Determining negative sequence currents of turbine generator rotors

Bach

Wohner

Takahashi

et al. 2009

2009 International Conference on Electrical Machines and Systems

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In parallel to their dynamic duty synchronous generators must be capable of bearing permanently an additional negative sequence current of up to 10% of the rated current according to the IEC 60034-1 standard. On turbine generators this does not only charge the damper winding but causes eddy currents and losses in the solid rotor iron in parallel. The complex current distribution cannot yet be satisfactorily calculated. The paper presents a new method of calculating these currents based on a lumped circuitry taking into account even the cross slits in the pole face. Target of the development is a fast routine calculation tool for determining the negative sequence current capability of a rotor already in the design stage of a generator. 3D-FEM reference calculations were performed as well as measurements on a rotor mock-up for studying complex local current distributions e.g. in the vicinity of the cross slits and the rules to be implemented in the lumped circuit network. FEM calculations themselves, affordable for research efforts, are considered too laborious and time consuming for being considered as routine design calculation tools.

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Section: A Comparison Of Resultssupporting

confidence: 85%

Determining negative sequence currents of turbine generator rotors

Bach

Wohner

Takahashi

et al. 2009

2009 International Conference on Electrical Machines and Systems

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“…Reference presents the dynamic analysis of eddy currents and losses of a synchronous generator and a new calculation method based on a lumped circuitry. The test results of eddy current distribution, loss distribution and resulting temperature distribution are calculated and compared in . At present, the finite element method is often used to calculate the negative‐sequence losses and rotor heating.…”

Section: Introductionsupporting

confidence: 87%

“…7 and 9 of Table . When 0.25 ≥ I 2 * ≥ 0.16, the main opinion is as follows: Although the duration time is long, which causes the actual value of I 2 * 2 t to be larger than the standard value, the negative‐sequence energy is small in per unit time, and the average and local temperature rise is also small during this long period of time considering the cooling influence on the rotor surface. This situation is consistent with the main point of : The rating is meaningless because thermal diffusion can mean that a generator can stand nearly any value if the imbalance currents are sufficiently small and the time is sufficiently long. Hence, this type of incident does not cause rotor damage, such as in No.…”

Section: Problems Of Traditional Transient Negative‐sequence Ratingmentioning

confidence: 99%

Improvement of the transient negative-sequence rating formula for large generators based on the negative-sequence current component

Guo

et al. 2015

Int. Trans. Electr. Energ. Syst.

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Summary This paper proposes an improved transient negative‐sequence calculation formula for a large‐capacity nuclear power generator system under unbalanced network conditions. Because of the disadvantages of traditional transient negative‐sequence ratings, I2*2 t is concluded to be inadequate for rating the generator imbalance capability. In fact, many factors, such as the possible fault asymmetry, the duration of the fault and non‐periodic components, should also be considered when rating a generator. According to the inherent relation between rotor heating and generator imbalance capability, the non‐periodic component is added to the improved transient negative‐sequence formula. In this paper, an AP1000 nuclear turbo‐generator was examined as a model to systematically analyse the electromagnetic properties and generator transient negative‐sequence capability affected by different types of typical short circuits. A comprehensive comparison based on accident examples, experimental results and extensive simulations shows that the improved transient negative‐sequence formula not only significantly enhances the assessment accuracy of large‐capacity generator imbalance capability but also provides a theoretical reference for the related research of large‐capacity generator systems. Copyright © 2015 John Wiley & Sons, Ltd.

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“…For decades, the internal fault digital research methods of the stator winding of synchronous generator can be divided into the following categories: symmetrical components, phase coordinate method, multi-loop analysis and finite element method [8][9][10][11][12]. Symmetrical components which can be see that three-phase current is superimposed by positive sequence components, negative sequence component and zero sequence component.…”

Section: The Calculation Of Transient Negative Sequence Componentmentioning

confidence: 99%

Study on Transient Negative Sequence Current Calculation and Harmonics Characteristic Analysis for Nuclear Half-Speed Turbine Generator

Dong¹,

Ge²,

Liang³

2015

IJHIT

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In recent years, with the rapid development of China's nuclear power industry, nuclear generator has also been actively developed. Because the unit capacity of the generator is increasing, so working life and operational reliability of the generator are also being tested. Among them, transient thermal running ability of the generator is one of the key factors affecting working life and operational reliability of the generator. This paper mainly analyzed the negative sequence current and the transient negative sequence component of the generator during asymmetric operation, and elaborates the principle of the generator negative sequence component harmonic. The paper has reference value for in-depth study of the generator negative sequence component.

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Analysis and Testing of Negative Sequence Heating of Turbine Generator Rotors

Cited by 4 publications

References 0 publications

Determining negative sequence currents of turbine generator rotors

Determining negative sequence currents of turbine generator rotors

Improvement of the transient negative-sequence rating formula for large generators based on the negative-sequence current component

Study on Transient Negative Sequence Current Calculation and Harmonics Characteristic Analysis for Nuclear Half-Speed Turbine Generator

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