Русская версия English version

Operational analysis of distance protection on single power supply lines in case of unbalanced short-circuits in the secondary winding of the «wye-delta» phase displacement group transformer

V.A. Shuin, M.S. Al-Homidi, V.V. Mozhzhukhina, T.S. Frolova

Vestnik IGEU, 2018 issue 5, pp. 39—45

Download PDF

Abstract in English: 

Background. Distance protection is normally used to increase the efficiency of distant backup protection in case of phase-to-phase short circuits in 110–220 kV transmission lines. A host of factors influence the sensitivity of distance protection backup stage in case of unbalanced phase-to-phase short-circuits in the secondary winding of step-down and branch stations, the main ones being the «star-delta» transformation and the transient resistance at the fault site. The currently used methods of estimating the actuation setpoints of distance protection backup stages do not take into account the complex effect of these factors on the resistance value and angle at the protection terminals, which can lead to unintended failures of protection equipment to operate. Therefore, an analysis of the performance features of distance protection backup stages for phase-to-phase unbalanced short-circuits in the secondary winding of «star-delta» transformers is an urgent problem aimed at making the actuation setpoint selection methods more exact.

Materials and methods. To analyze the influence of the «star-triangle» transformation and transient resistance at the fault site in case of unbalanced two-phase and three-phase short circuits, we used simulation by analytical and simulation mathematical models.

Results. An analytical solution has been obtained for the reactive and active components of primary resistance at distance protection terminals in case of unbalanced two-phase and three-phase resistive short circuits in the secondary winding of transformers with the most common «star-delta» winding group. The reliability of this solution was verified on a simulation model in the Simulink simulation system.

Conclusions. The obtained analytical expressions for the active and reactive components of resistance relay measurement in case of unbalanced resistive short-circuits in the secondary winding of «star-delta» transformers allows us to increase the accuracy and sensitivity of the methods of selecting the actuation setpoint of distance protection backup stages with different operating characteristics in single-side power supply transmission lines.

References in English: 

1. Fedoseev, A.M. Releynaya zashchita elektroenergeticheskikh sistem  [Relay protection of electric power systems]. Moscow: Energoatomizdat, 1984. 520 p.

2. Nagay, I.V., Nagay, V.I. Problemy i resheniya dal'nego rezervirovaniya transformatorov otvetvitel'nykh i promezhutochnykh podstantsiy [Problems and solutions for remote backup of transformers of branch and intermediate substations]. Releyshchik, 2009, no. 4, pp. 30–35.

3. Nagay, I.V. Dal'nee rezervirovanie v setyakh 6–110 kV. Problemy i resheniya [Remote back-up in 6–110 kV networks. Problems and solutions]. Novosti ElektroTekhniki, 2010, no. 6(66), pp. 28–30.

4. Nagay, V.I. Releynaya zashchita otvetvitel'nykh podstantsiy elektricheskikh setey [Relay protection of branch stations of electrical networks]. Moscow: Energoatomizdat, 2002. 312 p.

5. Nagay, V.I., Maruda, I.F., Nagay, V.V. Rezervirovanie releynoy zashchity i kommutatsionnykh apparatov elektricheskikh raspredelitel'nykh setey [Backup relay protection and switching devices of electric distribution networks]. Rostov-on-Don: Izdatel'stvo zhurnala «Izvestiya vuzov. Severo-Kavkazskiy region», 2009. 316 p.

6. Rukovodyashchie ukazaniya po releynoy zashchite. Vypusk 7. Distantsionnaya zashchita liniy 35–330 kV [Guidelines for relay protection. Issue 7. Remote protection of 35–330 kV lines]. Moscow: Energiya, 1966. 172 p.

7. Metodicheskie ukazaniya po raschetu i vyboru parametrov nastroyki (ustavok) mikroprotsessornykh ustroystv releynoy zashchity i avtomatiki proizvodstva OOO NPP «EKRA», «ABB», «GE Multilin» i «Alstom grid»/«Areva» dlya vozdushnykh i kabel'nykh liniy s odnostoronnim pitaniem napryazheniem 110–330 kV [Guidelines for the calculation and selection of the settings (actuation setpoint) of microprocessor relay protection and automation equipment produced by EKRA Research and Production Enterprise Ltd, ABB, GE Multilin and Alstom grid / Areva for air and cable lines with 110–330 kV single-side voltage supply]. Moscow: OAO «FSK EES», 2015.

8. Rekomendatsii po raschetu ustavok rezervnykh zashchit LEP VN na baze shkafov NPP «EKRA» [Recommendations for calculating the settings of backup protection of high voltage transmission lines using cabinets produced by EKRA Research and Production Enterprise Ltd]. Cheboksary, NPP «EKRA»: Versiya 12. 2014. – Cheboksary: OOO NPP «EKRA». Available at: http://www.ekra.ru/dokumentaciya/rza-podstancionnogo-oborudovanija-110-2....

9. Atabekov, G.I. Teoreticheskie osnovy releynoy zashchity vysokovol'tnykh setey [Theoretical bases of relay protection of high-voltage networks]. Moscow; Leningrad: Gosenergoizdat, 1957. 344 p.

Key words in Russian: 
ЛЭП высокого напряжения, междуфазные короткие замыкания, дальнее резервирование, дистанционные защиты, трансформация «звезда-треугольник», несимметричные короткие замыкания
Key words in English: 
high-voltage power lines, phase-to-phase short circuits, distant backup protection, distance protection, «wye-delta» transformation, unbalanced short-circuits
The DOI index: 
10.17588/2072-2672.2018.5.039-045
Downloads count: 
53