Analysis of very fast transient overvoltages (VFTO) from onsite measurements on 800 kV GIS

Li, Yunge; Zhang, Lin; Shi, Rong; Shi, Wei

doi:10.1109/tdei.2012.6396970

Cited by 37 publications

(3 citation statements)

References 30 publications

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“…They ensure the passage of electric current through the walls (structure of a transformer, walls of substations, etc.) as well as the connection between high voltage equipment, such as transformers, generators, Gas Insulated Switchgear (GIS), and the lines of the electrical network [1]- [3]. However, this very essential element in the electrical grid is known to be the most critical and sensitive [4], [5].…”

Section: Introductionmentioning

confidence: 99%

High Frequency Model of Power Transformer Bushing for Very Fast Transient Studies

Messadi,

Zouaghi,

Ferdjallah-Kherkhachi

et al. 2023

IEEE Access

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Fast and very fast transient overvoltages generally appear during switching operations within electrical substations. The oscillatory nature of such phenomena with frequencies that can reach several tens of megahertz tends to degrade the lifetime of high voltage equipment such as bushings and transformers, inducing partial discharges activity or breakdown of the insulation system. According to several case studies, bushings are one of the most sensitive parts to such overvoltages, indeed, a failure in a bushing will in most cases lead to a failure of the transformer, often catastrophically. Generating such overvoltages with a very high frequency character and considerable amplitude can be very difficult, moreover, studying the effect of such overvoltages on the insulated bushings is not easy, even experimentally. Therefore, a simulation of the fast transients in the system can be very useful to understand the consequences of such phenomena. In this context, this document aims to propose a model of high voltage capacitive graded oil impregnated paper (OIP) bushing based on a distributed electrical circuit. The equivalent circuit is constructed based on the geometric design and electrical properties of the materials. The model was developed and implemented using Matlab/Simulink® software, and was validated with experimental measurements based on impedance sweep frequency analysis. The modeling results are in a good agreement with the experimental ones. INDEX TERMSBushing, distributed circuit model, high voltage, high frequency, impedance analysis, numerical modeling, overvoltage, power transformer, very fast transient.

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Section: Introductionmentioning

confidence: 99%

High Frequency Model of Power Transformer Bushing for Very Fast Transient Studies

Messadi,

Zouaghi,

Ferdjallah-Kherkhachi

et al. 2023

IEEE Access

View full text Add to dashboard Cite

show abstract

“…Because the rising or falling edges of the VFTO are uncertain, the position at which the VFTO edges appear on the power frequency voltage is not clear. When breakdown occurs at a lower power frequency voltage, the VFTO edge amplitude may not exceed the power frequency voltage, resulting in missed triggering [10, 11]. External trigger.…”

Section: Introductionmentioning

confidence: 99%

“…When breakdown occurs at a lower power frequency voltage, the VFTO edge amplitude may not exceed the power frequency voltage, resulting in missed triggering [10,11]. 3) External trigger.…”

Section: Introductionmentioning

confidence: 99%

A low‐cost and high‐performance self‐trigger method for high‐voltage transient measurement

et al. 2022

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Stable triggering of acquisition devices is critical to accurately measure electromagnetic transients, especially for very fast transient overvoltages (VFTOs). A highly stable and lowcos t self-trigger method for transient measurement is proposed. An integrated low-voltage arm module was developed to synchronously realise the triggering and VFTO measurement. The trigger branch was developed using a high-pass filter. This component obtained the high-frequency component of the VFTO to trigger the oscilloscope. The trigger branch was integrated with the measurement branch through an impedance converter. An attenuator was implemented before the impedance converter to avoid overvoltage damage to the chip. The circuit parameters of the attenuator were optimised to alleviate the disturbance of the measurement branch. The calibration results demonstrated that the �1 dB bandwidth of the measurement branch in this system ranged from 11.8 Hz to 105 MHz. The low cutoff frequency of the trigger branch was 710 Hz. The VFTO waveforms generated by the operation of a disconnector in a real 252 kV gas insulated switchgear were measured using the proposed system. The test results verified that the self-trigger measurement system can provide stable trigger signals and accurately measure the VFTO waveforms.

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Frequency domain algorithm in the whole process simulation from VFTO to its conducted disturbance via voltage transformer in GIS substations

Zhao¹,

Chen

et al. 2022

Electric Power Systems Research

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Analysis of very fast transient overvoltages (VFTO) from onsite measurements on 800 kV GIS

Cited by 37 publications

References 30 publications

High Frequency Model of Power Transformer Bushing for Very Fast Transient Studies

High Frequency Model of Power Transformer Bushing for Very Fast Transient Studies

A low‐cost and high‐performance self‐trigger method for high‐voltage transient measurement

Frequency domain algorithm in the whole process simulation from VFTO to its conducted disturbance via voltage transformer in GIS substations

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