Vpliv izbire točk ločitve omrežja na določitev kratkostičnih ekvivalentov slovenskega elektroenergetskega omrežja s pomočjo modelov otokov

ROMIH REXHAJ, ADRIAN (author), Ažbe, Valentin (mentor)

V magistrski nalogi je obravnavana analiza kratkostičnih tokov v slovenskem elektroenergetskem sistemu po standardu IEC 60909, s poudarkom na metodologiji konstrukcije otoških ekvivalentov in njihovem vplivu na rezultate kratkostične analize. Uporabljen je bil programski paket DIgSILENT PowerFactory, v katerem je bil najprej pripravljen bazni model omrežja z vsemi generatorji (razen TEŠ5), nato pa še sedem različic modelov, kjer so bili generatorji nadomeščeni s togimi omrežji, oblikovanimi na osnovi kratkostičnih prispevkov, izračunanih v izoliranih otokih. Za namen primerjalne analize je bil model razdeljen na več ločenih otoških modelov, od katerih je vsak vključeval le eno zbiralko izmed tistih, ki jih opredeljuje metodologija ENTSO-E kot nosilke kratkostičnih prispevkov. V vsakem otoku so bili ohranjeni samo lokalni viri kratkostične moči (npr. generatorji), ostali deli sistema pa niso bili modelirani. Na ta način je bilo mogoče določiti posamezne prispevke kratkostične moči po zbiralkah, ki se kasneje uporabijo kot vhodni podatki v skupni evropski model. V sklopu priprave podatkov so bili iz tehnične dokumentacije prenosnih daljnovodov Elektroinštituta Milan Vidmar (EIMV) s pomočjo Python skript izvlečeni in v model vneseni natančni parametri daljnovodov, zlasti ničelne komponente impedanc. Za vsako otoško verzijo so bila v model vključena toga omrežja na zbiralkah, ki so v posameznem otoku vsebovale vir kratkostične moči, in izveden je bil ponoven izračun kratkostičnih veličin. Dobljeni rezultati so bili primerjani z baznim primerom, pri čemer je bila uporabljena metoda najmanjših kvadratov odstopanj. Analiza je pokazala, da so razlike med posameznimi verzijami zelo majhne. V večini primerov so se vrednosti razlikovale za manj kot 5 %, kar pomeni, da je metoda relativno neobčutljiva na izbiro točk mrežnega prereza. To potrjuje uporabnost pristopa za poenostavljeno modeliranje nacionalnih sistemov v skladu z zahtevami ENTSO-E, saj omogoča zanesljive rezultate brez potrebe po vsakokratnem iskanju optimalne topologije otokov.

• Language: Slovenian
• Keywords: kratkostični tokovi, IEC 60909, otoški ekvivalent, toga omrežja, PowerFactory, slovensko prenosno omrežje, ENTSO-E, metoda najmanjših kvadratov, kratkostična moč, sistemska analiza
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FE - Faculty of Electrical Engineering
• Year: 2025
• PID: 20.500.12556/RUL-175426
• COBISS.SI-ID: 258125315
• Publication date in RUL: 27.10.2025

Secondary language

• Language: English
• Title: Impact of Network Separation Point Selection on the Determination of Short-Circuit Equivalents of the Slovenian Power System Using Island Models

Abstract

This master's thesis addresses the analysis of short-circuit currents in the Slovenian power system based on the IEC 60909 standard, with a focus on the methodology for constructing islanded equivalents and their impact on short-circuit calculation results. The analysis was carried out using the DIgSILENT PowerFactory software package. First, a base network model with all generators (excluding TEŠ5) was prepared, followed by seven versions in which generators were replaced with equivalent voltage sources (network feeders) based on short-circuit contributions calculated in isolated subsystems. To comparative analysis, the system was divided into multiple isolated island models, each containing a single busbar designated by the ENTSO-E methodology as a point of short-circuit contribution. In each island, only local sources of short-circuit power (e.g., generators) were retained, while the rest of the system was not modelled. This approach made it possible to determine individual short-circuit contributions per busbar, which are later used as input data in the common European model. During data preparation, technical documentation of transmission lines from the Electric Institute Milan Vidmar (EIMV) was used to extract accurate line parameters with the help of Python scripts, with particular attention to the zero-sequence impedance components. For each island version, equivalent network feeders were inserted at the busbars that included sources of short-circuit power, and a new short-circuit calculation was performed. The results obtained were then compared to the base case using the least squares method to evaluate deviations. The analysis showed that the differences between individual versions were very small. In most cases, the values deviated by less than 5 %, indicating that the method is relatively insensitive to the choice of network cut-in points. This confirms the practical applicability of the approach for simplified modelling of national systems in accordance with ENTSO-E requirements, as it enables reliable results without the need for repeatedly determining the optimal island topology.

• Keywords: short-circuit currents, IEC 60909, island equivalent, external grid, PowerFactory, Slovenian transmission network, ENTSO-E, least squares method, short-circuit power, system analysis