Nasičenje tokovnih transformatorjev

Bevc, Jure (author), Pantoš, Miloš (mentor)

V okviru magistrske naloge smo opisali različne vrste nasičenj tokovnih transformatorjev (TT) in razloge za njihov nastanek. Merjenje tokov je z vidika vodenja in zaščite naprav in omrežja nujen proces. Ker pri prenosu in distribuciji električne energije tečejo v omrežju zelo veliki tokovi, je potrebno tok pred uporabo v sistemih vodenja in zaščite, t.i »sekundarnih sistemih« pretvoriti na nižjo vrednost. To naredimo s TT. Magistrska naloga zajema vpogled v delovanje TT s feromagnetnim jedrom, vplive na nasičenje transformatorskega jedra in ukrepe, s katerimi nasičenje preprečimo. Pri meritvah smo uporabili strojno in programsko opremo Omicron. Tokovniku na katerem smo testirali vplive na nasičenje magnetnega jedra, smo z orodjem CT Analyzer izmerili magnetilno krivuljo. Nato smo v laboratoriju pripravili testni poligon, s katerim smo preučevali vplive izmenične komponente toka, enosmerne komponente toka in bremena na nasičenje magnetnega jedra tokovnega transformatorja. Od strojne opreme smo uporabili CMC 256-6, CMC 356, dva pred upora in drsni upor. Tok z enosmerno komponento smo generirali s pomočjo programa NetSim, izmenično komponento s programom QuickCMC, vse odzive TT pa smo posneli s pomočjo programa Enerlyzer. Rezultati magistrske naloge kažejo na to, da prevelika amplituda izmenične komponente toka, prisotnost enosmerne komponente v primarnem toku in večje breme na sekundarnih sponkah TT rezultirajo v hitrejšem nasičenju transformatorskega jedra. Nasičenje TT se na sekundarnem toku odraža v zmanjšani amplitudi, povečani frekvenci, pojavijo se višje harmonske komponente in poveča se fazni zamik med kazalcem primarnega in sekundarnega toka.

• Language: Slovenian
• Keywords: tokovni zaščitni transformator, feromagnetno jedro, vplivi na nasičenje, zaščita.
• Work type: Master's thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2020
• PID: 20.500.12556/RUL-117603
• Publication date in RUL: 17.07.2020

BEVC, Jure, 2020, Nasičenje tokovnih transformatorjev [online]. Master’s thesis. [Accessed 28 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=117603

Secondary language

• Language: English
• Title: Current transformer saturation

Abstract

In the master's dissertation we described different types of current transformer saturations and their causes. Measuring of currents is essential to ensuring effective management and protection of equipment and electricity grid. Very high currents are present in the grid during transfer and distribution of electrical energy, therefore the current to be used in protection and control system, the so-called “secondary systems”, must be transformed to a lower value using a current transformer. The dissertation includes an overview of current transformers with ferromagnetic core, possible causes of saturation in the transformer core, and actions to prevent potential saturation. Omicron hardware and software was used for the measurements. Magnetization curve of current transformer, that we tested for different type of saturation, was measured using CT Analyzer tool. Than we prepared a laboratory test which studied the impact of alternating current component, direct current component, and load on a saturation of current transformer’s ferromagnetic core. Test was executed using CMC 256-6, CMC 356, two shunt resistors, and a sliding resistor. NetSim software was used for generating direct current, QuickCMC for generating alternating current and all responses from current transformer were recorded using Enerlyzer software. Results of the master's dissertation show that transformer core becomes saturated faster when alternating current component is too high, direct component is present in the primary current, and when the load of current transformer is increased. The impact of current transformer saturation on secondary current is shown in smaller amplitude and frequency, higher harmonic components, and increase in the phase angle between primary and secondary current indicators.

• Keywords: protection current transformer, ferromagnetic core, saturation causes, protection.