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4 Present Problems of Power System Control

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On interaction between circuit-breaker and network at small inductive currents' switching-offs

100%

Lazimov T. , Saafan E.

Present Problems of Power System Control

2011

tom Nr 1

29-37

Results of an investigation of interaction between circuit-breaker against its dielectric strength restoration law and parameters such as chop current and operation time (all conditioned by the circuit-breaker type and arc quenching medium) at small inductive currents' switch-offs are presented in this article. The results include curves of transitional voltages at switching under consideration and also conclusions on dependence of overvoltages and recovery voltages ratios on re-ignitions in inter-contact space. The results concerning investigation of stability are also presented. The analyzed methods were investigated from the point of view of stability in wide range of simulation parameters.

W artykule przedstawiono rezultaty badania wzajemnego powiązania rodzaju wyłącznika oraz prawa odbudowy wytrzymałości dielektrycznej i jego parametrów determinowanych rodzajem wyłącznika oraz zastosowanym medium gaszenia łuku), takich jak prąd ucięcia oraz czas wyłączenia podczas wyłączania małych prądów indukcyjnych. Badania dotyczyły określania napięć przejściowych podczas rozważnych operacji łączeniowych oraz zależności przepięć i napięć powrotu na ponowne zapłony w przestrzeni między biegunami wyłącznika. Przedstawiono również rezultaty badań stabilności obliczeń, przeprowadzonych w szerokim zakresie parametrów symulacji.

Transitional processes at capacitive currents switching-off by single and double-break interrupters of vacuum circuit breakers

100%

Lazimov T. , Saafan E.

Present Problems of Power System Control

2014

tom Nr 5

33—43

Vacuum circuit breaker technology based on double-break vacuum interrupters has become the most requirements of high voltage circuit breakers that not environmentally harmful. The vacuum interrupter has an excellent ability to deal with the steep rising part of the transient recovery voltage, which makes it faster in the current interruption process. This paper presents results of computer simulations conditioned by capacitive currents switching-offs by using single and double interrupters of vacuum circuit breakers. These results demonstrate that use of double-break circuit breakers leads to notable decreasing of switching overvoltages and allows in the same time to meet the dielectric requirements for high voltage vacuum circuit breakers.

Influence on heterogeneous earth layers parameters’ contrast on ground return impedance

100%

Lazimov T. , Saafan E.

Present Problems of Power System Control

2015

tom Nr 6

15--20

Aerial electrical line’s impedances of ground return through heterogeneous and homogeneous grounds and their differences were calculated for the earth with different interlayer contrast of parameters for series thicknesses of the earth upper layer. Behavior of the impedance differences against changes of frequency and upper layer’s depth is investigated in the article. It was shown that the worst approach of relative differences to the zero takes place for the little thicknesses of the earth upper layer (less than 8 meters) and very high frequencies at which the impedance concept loses its certainty and physical meaning.

Transitional processes at switching-off unloaded power transmission lines by modern circuit-breakers and their computer simulation

100%

Lazimov T. , Saafan E.

Present Problems of Power System Control

2013

tom Nr 4

67--75

The article presents results of transitional processes computer simulation at switching-off unloaded power transmission line of rated voltage 220 kV by auto-compression (SF6) circuit-breakers. Transitional voltages (voltage across the line terminals and recovery voltage) at switching-off were calculated and studied in the research carried out. There was also considered dependence between transitional voltages magnitudes and power transmission lines lengths. There were studied some computational peculiarities of the problem under consideration. In particular, the numbers of pi-sections provided satisfactory adequacy of lines equivalency at computer simulation for their typical lengths were determined. There were also estimated optimum simulation parameters provided stability of transitional regime parameters.