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Limiting of internal overvoltages in electric networks of power station auxiliaries during single-phase ground faults

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Category: Electrical engineering

Last Updated on Wednesday, 14 January 2015 19:00

Published on Wednesday, 14 January 2015 19:00

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Authors:

M.S. Seheda, Dr. Sci. (Tech.), Professor, Lviv Polytechnic National University, Head of the Department of Electric Stations, Lviv, Ukraine

N.O. Ravlyk, Lviv Polytechnic National University, Assistant Lecturer of the Department of Electric Stations, Lviv, Ukraine

Abstract:

Purpose. Development of measures to limit the internal overvoltages in electric networks of power stations auxiliaries during single-phase ground faults in order to ensure the reliability of their operation.

Methodology. Mathematical model of the electrical network, control and protection devices in mesh-node coordinates was proposed. The asynchronous motor processes to analyze the electromagnetic processes in electric networks of power stations auxiliaries were taken into account. The internal overvoltages in electric networks of power stations auxiliaries during single-phase ground faults were analyzed using the methods of mathematical modeling based on digital models. The special measures to limit the internal overvoltage were proposed. In order to simulate the transverse asymmetry, including single-phase ground faults the capacitive elements were proposed for usage considering the second law of commutation.

Findings. The internal overvoltage in electric networks of power stations auxiliaries were investigated during single-phase ground faults using different limitation measures, in particular by installing of nonlinear surge protection devices and capacitor banks.

Originality. Inthe paper in order to restrict the internal overvoltage and improve the start-up conditions of synchronous and asynchronous motors it was proposed to install the capacitor banks on buses of power station auxiliaries. Proposed measures also allow solving the problem of the voltage regulation.

Practical value. The reliability of electrical networks of power station auxiliaries, as well as providing the technological process of electrical energy production by electrical stations depends on coordination of their insulation during single-phase ground faults. Currently such studies can be performed using mathematical experiments on digital models.

References:

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Seheda, M.S., Bahor, Z.M., Ravlyk ,N.O. and Bakalo, G.Sh. (2006), “Internal overvoltage in networks 6…10 kv and overvoltage protection”, Pratsi Instytutu Elektrodynamiky NAN Ukrainy, no. 1(13), pp. 23–30.

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