Izračun sil na opremo v zračno izoliranem stikališču

Brenčič, Aljaž (author), Mihalič, Rafael (mentor)

V Sloveniji se večina visokonapetostnih (VN) postrojev (stikalni postroji, transformatorske postaje, razdelilne transformatorske postaje) še vedno gradi v zračno izolirani tehnologiji. To velja skoraj izključno za napetostne nivoje 220 kV in 400 kV, prevladuje pa tudi pri postrojih napetostnega nivoja 110 kV. Za določitev mehanskih karakteristik vse opreme, ki se potrebuje za gradnjo zračno izoliranih postrojev in za gradnjo podpornih konstrukcij in temeljev, na katere se namešča VN oprema, je nujno prepoznati in izračunati obremenitve, ki so jim navedeni elementi izpostavljeni v normalnih in v izrednih razmerah. Medtem, ko se za zbiralke vse več uporabljajo cevni vodniki, se za povezave med VN aparati iz različnih vzrokov še vedno večinoma uporabljajo vrvni vodniki. Poleg večjih elementov, kot so naprave za transformacijo in kompenzacijo, so tipični VN aparati, ki jih vgrajujejo v razdelilne in transformatorske postaje odklopniki, ločilke, napetostni in tokovni transformatorji, podporni izolatorji in prenapetostni odvodniki. V delu se osredotočamo na prepoznavi in določitvi sil, ki lahko med obratovanjem delujejo na VN aparate in na konstrukcijske in gradbene elemente, na katere nameščamo opremo. Poleg sil, ki nastopajo v stacionarnih pogojih obratovanja, so za določitev mehanske vzdržnosti opreme in pripadajočih konstrukcijskih ter gradbenih elementov merodajni mehanski učinki izjemnih pojavov, do katerih lahko pride med obratovanjem. Med te, poleg potresov, štejemo tudi sile na VN opremo zaradi učinka visokih elektromagnetnih polj med zemeljskimi in kratkimi stiki. Izkazalo se je, da so ravno slednje merodajne za zahtevane mehanske karakteristike opreme in konstrukcij. Cilj dela je izdelati programsko orodje za izračun obremenitev VN opreme. Na trgu je sicer dostopna programska oprema, ki med drugim omogoča računanje sil v stacionarnih in izrednih stanjih, vendar zahteva podatke, s katerimi projektant ob začetku načrtovanja VN postroja še ne razpolaga. Postopek projektiranja bi zato znatno olajšal pripomoček, ki bi že v zgodnjih fazah projektiranja posredoval podatke, s pomočjo katerih postroj zasnujemo tako, da izberemo ustrezno VN opremo. Postopka projektiranja tako ni potrebno izvajati iterativno, oziroma bi bilo to potrebno le izjemoma, če se npr. post festum izkaže, da postroj ne zadošča zahtevam. Iz praktičnih razlogov smo omenjeno programsko orodje izvedli v okolju VBA Excel. Rezultate izračuna smo primerjali z dobljenimi s programom Primtech 3D. Ocenjujemo, da primerljivost rezultatov potrjuje ustreznost izvedbe našega programskega orodja.

• Language: Slovenian
• Keywords: zračno izolirana stikališča, kratki stiki, mehanske obremenitve, gibljivi vodniki
• Work type: Master's thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2023
• PID: 20.500.12556/RUL-144997
• COBISS.SI-ID: 149419011
• Publication date in RUL: 29.03.2023

Secondary language

• Language: English
• Title: Calculation of forces on equipment in an air-insulated switchyard

Abstract

In Slovenia, most high-voltage (HV) installations (switchgear, transformer substations, distribution transformer substations) are still built using air-insulated technology. This applies almost exclusively to voltage levels of 220 kV and 400 kV, but also prevails in installations of voltage level of 110 kV. In order to determine the mechanical characteristics of all the equipment needed for the construction of air-insulated installations and for the construction of supporting structures and foundations on which HV equipment is installed, it is necessary to identify and calculate the loads to which the listed elements are exposed in normal and extraordinary conditions. While tubular conductors are increasingly being used for busbars, stranded conductors are still mostly used for connections between HV devices for various reasons. In addition to larger elements such as transformation and compensation devices, typical HV devices installed in distribution and transformer substations are circuit breakers, disconnectors, voltage and current transformers, support insulators and surge arresters. In this paper, we focus on identifying and determining the forces that can act on HV devices during operation and on the structural and building elements on which the equipment is installed. In addition to the forces that occur in stationary operating conditions, the mechanical effects of exceptional phenomena that may occur during operation are relevant for determining the mechanical inertia of the equipment and related structural and building elements. Among these, in addition to earthquakes, we also count forces on HV equipment due to the effect of high electromagnetic fields between short circuits. It turned out that these are authoritative for the required mechanical characteristics of equipment and constructions. The aim of this paper is to create a software tool for calculating the loads of HV equipment. Already available software among other things, enables the calculation of forces in stationary and extraordinary situations, but it requires data that the designer does not yet have at his disposal when planning the HV installations. The design process would be significantly facilitated by a tool, that would provide data in the early stages of design, with the help of which we design the installations by choosing the appropriate HV equipment. Therefore, the design process does not need to be carried out iteratively or it would only be necessary in exceptional cases, for example, if it post festum turns out, that the device does not meet the requirements. For practical reasons, we implemented the mentioned software tool in the VBA Excel environment. The calculation results were compared with those obtained with the Primtech 3D program. We estimate that the comparability of the results confirms the adequacy of the implementation of our software tool.

• Keywords: air-insulated switchyards, short circuits, mechanical loads, flexible conductors