Dependence of the Chopping Current Level of a Vacuum Interrupter on Parallel Capacitance

Vacuum circuit breaker operation causes transient overvoltages that may lead to severe damages to transformer insulation. Since the parameters affecting these overvoltages have stochastic nature, a statistical analysis may provide detailed insight into the overvoltages from the point of view of insulation coordination applications. In this paper, a statistical analysis of the overvoltage variations of the step-up transformer during vacuum circuit breaker operation is conducted. Some variables, including switching angle, current chopping, high-frequency current quenching capability, and wind turbine power, are assumed as random variables. Besides, some indicators representing the switching overvoltage characteristics such as the amplitude, the number of restrikes, and the rate of rise are extracted. By performing a probabilistic analysis, the destructiveness due to switching overvoltages on typical transformer insulation can be investigated. The sensitivity of different surge protective devices and their effectivities are also analyzed and statistically evaluated. The applied methodology is very useful because of the stochastic nature of the switching overvoltages. In this work, the impact of protective equipment on each of the overvoltage indicators is analyzed. It is also found that considering only the amplitudes of transient overvoltages is not enough to draw conclusions about the safety of the transformer when exposed to frequent switching surges.

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“…Experimental tests conducted in Ref. [11] however, showed the low dependency of this parameter on the operation instant.…”

Section: Introductionmentioning

confidence: 93%

“…The considerations for current chopping in this study are adopted from the experimental measurements in Ref. [11]. Therefore, current chopping has been assumed as a random variable with a log-normal PDF, and the values distributed between 3 to 6 A.…”

Section: Current Choppingmentioning

confidence: 99%

Probabilistic analysis of switching transients due to vacuum circuit breaker operation on wind turbine step-up transformers

Ghasemi

Allahbakhshi

Behdani

et al. 2020

Electric Power Systems Research

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“…A research study by Liljestrand and Lindell [1] has shown how effective SA can be in mitigating switching transients on disconnection. It has also been shown in a research study by Dullini, Lindell, and Liljestrand [2] that, with the addition of a surge capacitor, it was possible to reduce switching overvoltages significantly as well as reduce the number of SA operations.…”

Section: Technique Applicationmentioning

confidence: 99%

“…They found that by adding a surge capacitor between the transformer terminals and the ground, the transient overvoltage during switching decreased by a factor of 6. The additional load‐side surge capacitor influences the chopping current by acting as a source, sustaining periods of momentary current reduction after an arc instability and allowing the excitation of a subsequent arc instability during this period [2]. However, the optimisation of the capacitance or use of a variable capacitor as well as the methods of closed‐loop switching control of the capacitor with the VCB are not covered in this research.…”

Section: Over‐voltage Protectionmentioning

confidence: 99%

“…The consequences of energizing and disconnecting the train's transformer or transformers routinely at neutral sections are reviewed. State‐of‐the‐art techniques used to limit transient overvoltages on the load side of the circuit breaker (CB) due to switching of the inductive transformer load are reviewed, including the following: Surge arresters (SAs) [1]; Surge capacitors [2]; Resistor capacitor (RC) snubbers [3]; Pre‐insertion resistors (PIR) [4]; Chokes [5]; and Controlled switching of the VCB [6]. …”

Section: Introductionmentioning

confidence: 99%

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Voltage transient management for Alternating Current trains with vacuum circuit breakers

Moore

Schmid

Tricoli

2021

IET Electrical Syst in Trans

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Alternating current power supplies and rolling stock with 25 kV (50 or 60 Hz) and 15 kV (16.7 Hz) traction systems do not have the characteristics and behaviour of a typical three-phase medium-voltage distribution system. Switching inductive loads with a vacuum circuit breaker (VCB) in MV traction systems poses familiar challenges as well as some unique challenges, such as the crossing of phase change neutral sections. Transformers represent highly inductive loads due to their iron core and, thus, the consequences of energizing and disconnecting a transformer and dealing with the energy stored in its inductance must be considered within a system context. The authors of this study consider two transient phenomena associated with switching single-phase, medium voltage, AC traction transformer loads using a VCB on railway rolling stock: (i) switching transients that occur when disconnecting a transformer, particularly if lightly loaded and (ii) pre-ignition and current inrush that occurs when energizing a transformer. Both phenomena can cause reliability problems, requiring increased system maintenance or resulting in premature failures of system components. The authors review the use of controlled switching and other state-of-the-art methods to prevent or limit voltage transients when switching a transformer load by means of a VCB. The effective application of such techniques has been demonstrated in previous research or established in practical applications by manufacturers and electrical distribution network companies.This is an open access article under the terms of the Creative Commons Attribution-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited and no modifications or adaptations are made.

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Investigation of the structure and properties of electrodeposited Cu/graphene composite coatings for the electrical contact materials of an ultrahigh voltage circuit breaker

Cui

Han

Zhu

et al. 2019

Journal of Alloys and Compounds

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Dependence of the Chopping Current Level of a Vacuum Interrupter on Parallel Capacitance

Cited by 4 publications

References 5 publications

Probabilistic analysis of switching transients due to vacuum circuit breaker operation on wind turbine step-up transformers

Probabilistic analysis of switching transients due to vacuum circuit breaker operation on wind turbine step-up transformers

Voltage transient management for Alternating Current trains with vacuum circuit breakers

Investigation of the structure and properties of electrodeposited Cu/graphene composite coatings for the electrical contact materials of an ultrahigh voltage circuit breaker

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