Wyniki wyszukiwania - BazTech

1

Wykorzystanie prądu w obwodzie uziemienia żył powrotnych kabli elektroenergetycznych SN do wykrywania i lokalizacji zwarć doziemnych w sieciach SN

Łowczoski Krzysztof, Lorenc Józef, Zawodniak Józef

Wiadomości Elektrotechniczne

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2020

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R. 88, nr 12

9--14

PL

W artykule przedstawiono zagadnienia związane z wykrywaniem i lokalizacją zwarć doziemnych w sieciach SN. Uwagę skupiono na liniach kablowych i kablowo-napowietrznych. Przedstawiono wielkość kryterialną – prąd w obwodzie uziemienia żył powrotnych, po czym opisano sposób wykorzystania prądu uziemiającego na potrzeby wykrywania i lokalizacji zwarć doziemnych w sieciach SN. W kolejnej części artykułu przedstawiono wyniki badań symulacyjnych dla różnych przypadków zwarć doziemnych w liniach kablowych i kablowo-napowietrznych. Przedstawione zależności stały się podstawą opracowania algorytmu wykrywania i lokalizacji zwarć omawianego w artykule. Rozważania potwierdzono, wykonując eksperyment sieciowy w sieci dystrybucyjnej SN.

EN

The paper presents issues related to the detection and location of earth faults in MV networks. Attention has been focused on cable and cable-overhead lines. The criterion value - the cable screen earthing current is presented, and then the method of utilization of the earthing current for the purpose of detection and location of earth faults in MV networks is described. The next part of the article presents the results of simulation tests for various cases of earth faults in cable and cable-overhead lines. The presented dependencies have become the basis for the development of the earth fault detection and location algorithm presented in the paper. The presented considerations were confirmed by performing a network experiment in the MV distribution network.

2

A relaying scheme for detection and classification of shunt faults in six-phase transmission system based on DFT-FIS approach

Ashok V., Yadav A.

Journal of Power Technologies

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2018

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Vol. 98, nr 2

202--211

EN

Hitherto many schemes based on the fuzzy system have been protected by a three-phase transmission system, but not by a six-phase transmission system. This paper sets out a novel protection scheme based on DFT-FIS approach for detection/classification of shunt faults in a six-phase transmission system. In this scheme, two separate DFT-FIS modules have been designed to detect the presence of fault in any of the six-phase(s) and to identify the presence of ground in the fault loop, thus classifying all 120 types of fault in a six-phase transmission line. The six-phase voltage and current signals are collected at one end of the transmission line only, thus circumvent dependence on a communication link for remote end data. A widerange of fault simulation studies were carried out in MATLAB/Simulink environment for all possible shunt fault combinations by varying fault locations, fault inception angle, fault resistance, short circuit capacity (SCC) of the source and at various fault conditions such as: close-in faults, remote-end faults, high resistance faults, including CT saturation. Furthermore, the relay operation time in fault detection/classification is less than one-cycle (<16.67ms) and since the scheme does not experience any malfunction it is deemed reliable and adaptable.

3

Tutorial on operating characteristics of microprocessor-based multiterminal line current differential relays

Kasztenny B, Benmouyal G, Altuve H J, Fischer N

Present Problems of Power System Control

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2013

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Nr 3

s. 5--73

EN

Line current differential (87L) protection schemes face extra challenges compared with other forms of differential protection, in addition to the traditional requirements of sensitivity, speed, and immunity to current transformer saturation. Some of these challenges include data communication, alignment, and security; line charging current; and limited communications bandwidth. To address these challenges, microprocessor-based 87L relays apply elaborate operating characteristics, which are often different than a traditional percentage differential characteristic used for bus or transformer protection. These sophisticated elements may include adaptive restraining terms, apply an Alpha Plane, use external fault detection logic for extra security, and so on. While these operating characteristics provide for better performance, they create the following challenges for users: x Understanding how the 87L elements make the trip decision. x Understanding the impact of 87L settings on sensitivity and security, as well as grasping the relationship between the traditional percentage differential characteristic and the various 87L operating characteristics. x Having the ability to transfer settings between different 87L operating characteristics while keeping a similar balance between security and dependability. x Testing the 87L operating characteristics. These issues become particularly significant in applications involving more than two currents in the line protection zone (multiterminal lines) and lines terminated on dual-breaker buses. This paper is a tutorial on this relatively new protection topic and offers answers to the outlined challenges.

4

New method of CT saturation detection

Bąk D., Dong X., Rebizant W.

Present Problems of Power System Control

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2012

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Nr 2

65-72

EN

A new method for detection of CT saturation is presented in this paper. The presented algorithm applies a new, innovative methodology mapping first order derivative of phase current signals into coordinates of a 3D vector. The comparison of proposed algorithm with standard one based on secondary current signal's second derivative is conducted and some of simulation results are presented to show the proposed algorithm effectiveness.

5

Generator split-phase protection

Kim S., Finney D., Fischer N., Kasztenny B.

Present Problems of Power System Control

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2012

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Nr 2

5-40

EN

The stator winding of a hydrogenerator is often made up of coils with multiple turns in the same slot. It is therefore possible for faults to develop between adjacent turns on the same phase (turn-toturn faults). These faults cannot be detected by the stator differential protection because there is no difference between the neutral- and terminal-side currents. Split-phase protection, an overcurrent element responding to the difference between the currents in the winding parallel branches, is typically provided to detect these faults. Ideally, the split-phase element should be sensitive enough to detect a single shorted turn. Despite the fact that the current in this turn can be six to seven times the machine nominal current, the current seen by the split-phase protection can be quite small, in the order of one-twentieth of the generator full-load current. In addition, a spurious split-phase current can be measured due to current transformer (CT) errors, saturation during external faults in particular. Therefore, primary considerations in the application of split-phase protection are the method of measuring the difference in the currents between the parallel branches and the proper selection of the CT used for this purpose.

6

Korekcja dynamiczna pojemnościowych przekładników napięciowych dla zabezpieczeń i lokalizacji zwarć

Rosołowski E., Iżykowski J., Pierz P., Balcerek. P., Saha M.

Przegląd Elektrotechniczny

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2009

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R. 85, nr 4

65-67

PL

Przedstawiono cyfrowy algorytm do kompensacji składowych przejściowych, które są generowane w obwodzie Pojemnościowego Przekładnika Napięciowego (PPN). Algorytm realizuje cyfrową inwersję uproszczonej transmitancji PPN. Zamieszczone przykłady pokazują poprawę uzyskaną w wyniku zastosowania korekcji, w odniesieniu do pomiaru wielkości kryterialnych zabezpieczeń oraz estymacji odległości do zwarcia.

EN

Digital algorithm for compensating transients, which are induced in the circuit of a Capacitive Voltage Transformer (CVT), has been presented. The algorithm is based on digital inversion of the CVT simplified transfer function. The included examples show the improvement of the measurement of protective criteria quantities and the distance to fault estimation, as a result of the applied dynamic compensation of a CVT.

7

Dynamiczna korekcja pojemnościowego przekładnika napięciowego dla potrzeb układów automatyki zabezpieczeniowej

Rosołowski E., Iżykowski J., Pierz P.

Zeszyty Naukowe. Elektryka / Politechnika Łódzka

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2008

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z. 116

21-30

PL

Przedmiotem rozważań jest korekcja stanów przejściowych, których źródłem są obwody pojemnościowych przekładników napięciowych (PPN). Pojemnościowe przekładniki napięciowe są powszechnie stosowane w torach pomiarowych układów automatyki zabezpieczeniowej, w szczególności w sieciach najwyższych napięć. Odznaczają się szeregiem zalet, ale też nie są pozbawione wad. W stanach nieustalonych, wtórne napięciowe sygnały pomiarowe mogą zostać zafałszowane, co w rezultacie może prowadzić do błędnego działania algorytmów pomiarowych i podejmowania błędnych decyzji, np. w układach automatyki zabezpieczeniowej.

EN

Digital algorithm for compensating transients, which are induced in the circuit of a Capacitive Voltage Transformer (CVT), has been presented. The algorithm is based on digital inversion of the CVT simplified transfer funetion. The included examples show the improvement of the measurement of protective criteria quantities and the distance to fault estimation, as a result of the applied dynamie compensation of a CVT.