A method of obtaining of electric arc model parameters for SF6 power breakers (original) (raw)

A METHOD OF OBTAINING OF ELECTRIC ARC MODEL PARAMETERS FOR SF6 POWER CIRCUIT BREAKERS

A new method of calculating parameters of electric arc model of SF 6 power circuit breaker is proposed. The methodology consists in the optimization of a theoretical function with respect to a group of parameters of model in order to achieve a better approximation to a set of experimental data. The theoretical function is an asymptotic solution for the voltage that is obtained for a selected period of time. The developed method is applied to obtain the parameters of an arc model previously published in the literature. By means of a variation of the cooling power P 0 +P 1 iu, a new electric arc model is obtained including the additional parameters of model. The new model has a very compact form and results in a better correlation between the theoretical voltage curves and the experimental oscillograms.

A method of obtaining of electric arc model parameters for SF6 power circuit breakers

IEEE EUROCON 2009, 2009

In this work, a new method for calculating the parameters of electric arc model for SF 6 power circuit breaker is proposed. The methodology consists in the optimization of a theoretical function with respect to a group of model parameters in order to achieve a better approximation to a set of experimental data. The theoretical function is an asymptotic solution of the equation for the electric arc model obtained in a selected period of time. The developed method is applied to calculate the parameters of an arc model previously published in the literature. By using the variation of the cooling power, an improved electric arc model is also obtained including its parameters. The new model has a very compact form and exhibit a good correlation between voltage curves measured and calculated.

Numerical Arc Model Parameter Extraction for SF6 Circuit Breaker Simulations

In recent years some work has been conducted in the area of circuit breakers modeling in order to improve the capability of high voltage circuit breakers through simulations. Most of the research has been concentrated in describing the circuit breaker behavior by mathematical modeling, as well as numerical modeling of the pre or post current zero periods. The fundamental problem when trying to implement the existing models is to obtain reliable values of the unknown parameters of the mathematical model. Through this work a modified Cassie-Mayr model has been implemented in both EMTP (Electro-Magnetics Transients Program) and MATLAB. The EMTP simulation produces current and voltage oscillograms that are then supplied to the optimization routine in MATLAB for evaluation and validation of the parameter extraction procedure. T he modified Cassie-Mayr model has proved to be a reliable tool for the study of arc interruption of high-pressure gas circuit breakers because it takes into account pre and post current-zero conditions. The Cassie-Mayr model has four constant parameters, which changes according to the device (interrupter) and external circuit conditions. This work aims to develop a better parameter extraction routine, which is based on the MATLAB optimization function of nonlinear least squares. In this work we present the results of the parameter extraction routine developed to determine the four parameters from voltage and current oscillograms of tested and/or simulated devices.

Arc models for simulating processes in circuits with a SF6 circuit breaker

2019

This paper demonstrates that if a linear dependence of arc dissipated power on power supplied is introduced at an initial stage of analysis, then, with some simplifying assumptions, the classical Mayr model is obtained. Similarly, if this dependence is taken into account in a model with residual conductance, the modified Mayr model is obtained. The study takes into consideration the local phenomenon of sudden voltage drop accompanying linear current decrease occurring in the circuit breaker. To account for this phenomenon, the Dirac delta function and its approximation by a Gaussian function, representing power or enthalpy disturbances, are introduced to the power balance equation. It is demonstrated that both variants yield the same effect, leading to identical differential equations. Macromodels of the circuit-breaker arc are created and connected with the power source circuit with lin- early decreasing current. The results obtained were found to be consistent with experimental da...

Modified arc models in a SF6 power circuit breaker

PRZEGLĄD ELEKTROTECHNICZNY, 2018

Selected operating properties of high voltage power switches that use SF6 as extinguishing medium have been described. Selected physical properties of switching arc that occurs in those devices have been presented, with special focus on results of experimental research conducted in KEMA laboratory in Netherlands. Important flaws of mathematical models of switching arc described in literature have been indicated, despite they include variation of dissipation power, as well as step decrease of voltage during linear decrease of current. Method for obtaining modified Mayr and hybrid models with aforementioned properties have been described. They differ from other known models by consistent introduction of preliminary assumptions and simpler form. Properties of these models have been researched using computer simulations. Their usefulness in engineering work have been demonstrated. Streszczenie. W artykule opisano wybrane właściwości eksploatacyjne wyłączników wysokonapięciowych mocy, które używają SF6 jako medium gaszeniowego. Zaprezentowano wybrane właściwości fizyczne łuku łączeniowego, który występuje w tych aparatach. Szczególną uwagę zwrócono na wyniki badań eksperymentalnych przeprowadzonych w laboratorium KEMA w Holandii. Wskazano na istotne mankamenty modeli matematycznych łuku łączeniowego opisywanych w literaturze, pomimo że uwzględniają one zmienność mocy rozpraszanej, a także skokowy spadek napięcia podczas liniowego zmniejszania prądu. Opisano metodę otrzymania zmodyfikowanych modeli Mayra i hybrydowego o wspomnianych wcześniej właściwościach. Od innych znanych modeli różnią się one konsekwentnym wprowadzaniem założeń wstępnych i prostszą postacią. Zbadano właściwości tych modeli za pomocą symulacji komputerowych. Wykazano przydatność tych modeli w pracach inżynierskich. (Zmodyfikowane modele łuku w wyłączniku mocy z SF 6).

BLACK BOX ARC MODELING OF HIGH VOLTAGE CIRCUIT BREAKER USING MATLAB/SIMULINK

iaeme

Over the years, as our knowledge of the interrupting process progressed, many techniques have been developed to test the circuit breakers and simulated arc model There are three models (Physical Model Black Box Model and Parameter Model) that describe the behavior of f arc. This paper evaluates the black-box arc model for circuitbreakers with the purpose of finding criteria for the breaking ability. A black-box model is a model that requires no knowledge from the user of the underlying physical processes. In this paper, knowledge of the physical processes is required when evaluating and developing the arc models. This paper is meant to give a detailed study of black box model with the purpose to evaluate, combine, improve and apply to already existing circuit-breakers. Cassie-Mayr arc models was evaluated. Cassie’s model gives good results for large currents, while Mayr’s model is better for currents near zero. Therefore, a combination of the Cassie and Mayr model will be used to obtain better result

Quenching Processes of Axially Inhomogeneous Arcs in SF6 Circuit Breakers

IEEE Transactions on Plasma Science, 1980

The description of the arc in a modern high-voltage SF6 circuit breaker by only one single-arc equation is not sufficiently exact for application, especially when using constant arc parameters. In typical nozzle configurations, arcs are generally being axial inhomogeneous. For these arcs, a theory is presented taking into account the gas-flow properties determining the axial structure. This is applied for investigating an arc consisting essentially of two different parts. It is shown, how to determine for these parts the arc parameters depending on the conductances, which are required for an appropriate mathematical description. As an example a computer simulation of the performance of the investigated circuit breaker is presented, and compared with corresponding full-scale interruption tests. Breaking capacity limit as well as the complete interaction phenomena between circuit breaker and test circuit are in agreement, proving the presented theory of an axially inhomogeneous arc.

Simulation of Arc Characteristics in Miniature Circuit Breaker

IEEE Transactions on Plasma Science, 2000

This paper focuses on the numerical investigation of arc plasma behavior in low-voltage circuit breaker with arcsplitting process included. A 3-D simulation model of a certain type miniature circuit breaker product is built and calculated, which is based on magnetohydrodynamics theory. Aside from coupled electromagnetic and gas dynamic interactions being considered as usual, a thin layer of nonlinear electrical resistance elements is used to represent the voltage drop of plasma sheath and the formation of new arc roots. Thus, the arc-splitting process with ferromagnetic plates can be included. Arc motion is described in detail by the temperature distribution. Some interesting phenomena are observed in the simulation, such as the arc root jumping from contact to arc runner, the arc back commutation before splitting into series arcs by metallic plates, new arc root formation in splitting process, and, finally, the arc go across the splitter plates in the chamber. Moreover, the simulation result is compared with experimental result, which shows good agreement.

Arc Cooling Mechanisms in a Model Circuit Breaker

IEEE Transactions on Power Delivery, 2000

Axially blown electric arcs in a model circuit breaker are investigated by electrical measurements and fast imaging with a high-speed camera for visualizing the arc structure. Parameters for a dynamic conductance model (known as the "black-box model" in the arc literature) are extracted from the electrical measurements for currents between a few tens of amperes and a few kiloamperes. The model is used for the prediction of the conductance-dependent cooling power and arc relaxation time, as well as the voltage-current characteristics of the arcs in our system. In order to work out the relevance of the different cooling mechanisms, an alternative and more physically based dynamic model for axially blown arcs is incorporated. It turns out that convective cooling predominates turbulent heat conduction and radiation cooling in the region of validity of the model. The result is consistent with the observed strong dependence of the cooling power on the flow conditions that are controlled by the blow-gas pressure and the geometry. Furthermore, the comparison between air and arcs indicates a considerable dependence of the conductance-cooling relation on the gas type.