Study of Abnormal Electrical Phenomena Effects on GSU Transformers

Dong, Xuzhu; Rosado, S.; Li, Fangxing; Wang, Nien-Chung; Line, E.-L.; Guo, Tzong‐Yih

doi:10.1109/mper.2002.4311851

Cited by 8 publications

(8 citation statements)

References 3 publications

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“…VFTOs typically have a very short rise time, in the range of 4 to 100 ns, and are followed by high frequency oscillations, in the range of 1 to 50 MHz. Therefore, the analysis of switching transients and very fast transients in GIS is extremely important [6][7][8][9][10][11]. Also, when lightning hits a nearby tower or the shield wire of an incoming line, this can cause a backflashover, which is when the resultant lightning surge enters the substation and may propagate inside depending on the substation layout.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Transient Overvoltages within a 345kV Korean Thermal Plant

Yeo¹,

Kim²

2012

Journal of Electrical Engineering and Technology

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-This paper presents the simulation results for the analysis of a lightning surge, switching transients and very fast transients within a thermal plant. The modeling of gas insulated substations (GIS) makes use of electrical equivalent circuits that are composed of lumped elements and distributed parameter lines. The system model also includes some generators, transformers, and low voltage circuits such as 24V DC rectifiers and control circuits. This paper shows the simulation results, via EMTP (Electro-Magnetic Transients Program), for three overvoltage types, such as transient overvoltages, switching transients, very fast transients and a lightning surge.

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Section: Introductionmentioning

confidence: 99%

Analysis of Transient Overvoltages within a 345kV Korean Thermal Plant

Yeo¹,

Kim²

2012

Journal of Electrical Engineering and Technology

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“…Gas-insulated substation (GIS) is widely used in electric power system in recent decades because of the advantages such as compact size, protection from pollution, a few maintenance, and high reliability. In spite of these advantages, GIS has its unique problems, due to reflections of switching transients at various junctions within the GIS the voltage increase very fast [1,2]. These transients are originated within a GIS any time there is an instantaneous change in voltage.…”

Section: Introductionmentioning

confidence: 99%

“…These transients are originated within a GIS any time there is an instantaneous change in voltage. These transients have a very short rise time, in the range of 4 to 100ns, and are normally followed by oscillations having frequencies in the range of 100kHz to 50MHz [2]. These transients cause traveling wave internally inside the GIS.…”

Section: Introductionmentioning

confidence: 99%

“…These transients cause traveling wave internally inside the GIS. This wave will travel from GIS bushing to external components, which can lead to damage the insulation of internal busbar and transformer, which influent the operating reliability of GIS, accelerate aging of transformer insulation and reduce transformer life [1][2][3]. Also Very fast transient overvoltages (VFTOs) associated with very fast transient currents (VFTCs) radiate electromagnetic fields during its propagation through the coaxial GIS bus section.…”

Section: Introductionmentioning

confidence: 99%

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Mitigation of Very Fast Transient Overvoltages at the More Sensitive Points in Gas-Insulated Substation

Said¹,

Badran²,

Abdallah³

2012

ijeei

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Switching operations in a gas insulated substations generate very fast transient over voltages (VFTO) which are dangerous for the transformer and the system insulation because of their short rise time. Under special circumstances the terminal over voltages can arise close to the transformer BIL. The suppression of VFTO is very important in GIS systems. Different techniques are applied to 245 kV GIS model. The simulation used ATP-EMTP package program to evaluate the VFTO at the sensitive points in GIS. The different results are compared to determine the effective mitigation method. The results show that the wave steepness and the amplitudes of VFTO can be reduced to about 1Pu with less oscillation frequency.

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“…Although switching have been reduced to an acceptable level in modern substation insulation coordination, still transformer failures related to switching operation are reported .…”

Section: Introductionmentioning

confidence: 99%

Suppression of very fast transients in gas‐insulated substation via terminal and capacitance components—feasibility study

Tavakoli

Gholami

Alamuti

2011

Int Trans Elec Energy Syst

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SUMMARY Reportedly, the switching operation in a gas‐insulated substation (GIS) can lead to deformation of transformer winding. Also, electromagnetic fields radiated because of switching operations get coupled to the control equipment or data cables present in the GIS. These problems during switching operations in the GIS depend on the wave shape of the very fast transient overvoltages (VFTOs) and the associated very fast transient currents (VFTCs). Available methods are utilizing ferromagnetic rings and resistors to suppress the stresses created by very fast transient (VFT) from the source side. These equipment are mounted on the conductors linked to the disconnector. However, current methods are only applicable before installation period and during the substation design stage. The aim of this paper is to investigate feasible methods for mitigation of the overvoltage magnitude of VFT and suppression of the resonant frequencies amplitude at the power transformer. The proposed method utilizes terminal and capacitance components to suppress VFTs in GIS. Its advantages are their simplicity and low cost of implementation along with producing minimal changes in the installed GIS. The effectiveness of the proposed method to mitigate overvoltage magnitude and resonant frequencies amplitude of VFT is presented via simulation. In addition, the amplitude and frequency spectrum of the VFTO and VFTC at the various locations have been analyzed in this paper. Copyright © 2011 John Wiley & Sons, Ltd.

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Study of Abnormal Electrical Phenomena Effects on GSU Transformers

Cited by 8 publications

References 3 publications

Analysis of Transient Overvoltages within a 345kV Korean Thermal Plant

Analysis of Transient Overvoltages within a 345kV Korean Thermal Plant

Mitigation of Very Fast Transient Overvoltages at the More Sensitive Points in Gas-Insulated Substation

Suppression of very fast transients in gas‐insulated substation via terminal and capacitance components—feasibility study

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