Iskanje po katalogu digitalne knjižnice

Opis: V sodobnih nizkonapetostnih omrežjih opažamo vedno večje zahteve po električni energiji in slabšanje kakovosti napajalne napetosti. V diplomski nalogi smo predlagali različne ukrepe za izboljšanje kakovosti napetosti. Posebej smo obravnavali regulacijo proizvedene jalove moči s fotonapetostnimi elektrarnami, uporabo baterijskih hranilnikov in dvig napajalne napetosti na nizkonapetostni strani transformatorja. Za realno omrežje s 55 odjemalci smo opravili stacionarne izračune, s katerimi smo določili napetostni profil omrežja in toke skozi vodnike. Opravili smo tudi dinamične izračune upadov napetosti zaradi zagonov toplotnih črpalk. Iz dobljenih rezultatov sklepamo, da bo v prihodnosti uporaba obravnavanih ukrepov igrala veliko vlogo za zagotavljanje ustrezne kakovosti napajalne napetosti.
Ključne besede: kakovost napetosti, nizkonapetostno omrežje, sodobni elementi nizkonapetostnega omrežja, izračuni pretokov energij, dinamični izračuni
Objavljeno v DKUM: 03.11.2020; Ogledov: 1074; Prenosov: 150
Celotno besedilo (3,30 MB)

Opis: Distribution Networks (DNs) are evolving from a once passive to an active part of the electricity network. This evolution is driven by the current political and environmental decisions, Directives and Incentives, as well as the technological development, observed in the everincreasing integration of renewable energy resources, advanced network control and measurement devices, the upcoming energy exibility market, etc. This Doctoral Thesis deals with the problem of optimization of the technical aspects of a DN operation, enabled by the proliferated integration of the photovoltaic systems (PV) and other active devices. The main objective of the Thesis is the optimization of a DN operation in terms of minimization of electrical energy losses while ensuring the proper voltage profiles and preventing thermal overloadingof lines. Therefore, three Differential Evolution-based optimization procedures were developed and tested on real medium and low voltage DNs. The first methodology determines the optimal rooftop surfaces for the installation of PV systems, yielding minimum annual energy losses. It is based on the simultaneous consideration of high-resolution spatio-temporal solar and PV potential data, as well as long-term measured profiles of consumption and generation of electrical energy within the network of a given configuration. The second algorithm minimizes network losses in a time-discrete operation point, by determining the optimal operation of the following active elements: PV systems capable of cooperation in reactive power provision, On-Load Tap Changer equipped transformer substations and remotely controlled switches for network reconfiguration. The final algorithm was developed by a proper consolidation of the first two approaches, yielding the synergistic effects expressed as the increase of loss reduction and network exibility. The results of the performed case studies show that the locations of the highest suitability for PV installation with respect to the solar energy availability, are not necessarily the best choice from the network operation standpoint. Therefore, both standpoints should be considered simultaneously when choosing the rooftop surfaces for PV installation. Furthermore, by determining optimal hourly operation of the considered active elements, not only the additional reduction of annual network losses was achieved, but also increased accommodation of the PV systems that doesn't violate operation constraints.
Ključne besede: distribution network, optimization of operation, active network elements, PV system placement, minimization of losses
Objavljeno v DKUM: 11.06.2020; Ogledov: 1867; Prenosov: 428
Celotno besedilo (44,58 MB)

Opis: Zaradi vse večje onesnaženosti zraka in vedno večje potrebe človeka po električni energiji bo v omrežje vključenih čedalje več razpršenih virov. Ti razpršeni viri nam povzročajo spreminjanje smeri pretoka energije. Cilj je ugotoviti kako ti razpršeni viri in veliki porabniki vplivajo na napetostni profil.
Ključne besede: napetostni profil, distribucijsko omrežje, izračun pretokov energije, metoda BFS, model omrežja.
Objavljeno v DKUM: 21.12.2018; Ogledov: 2155; Prenosov: 157
Celotno besedilo (2,34 MB)

Opis: Namen diplomske naloge je, da za trifazni vodno hlajeni asinhronski generator moči 5,5 kW, s pomočjo programskega paketa emLook naredimo izračune navijalnih podatkov in izberemo najbolj optimalno navijte. Izbrali smo ulomljeno koncentrično navitje in zanj opravili tudi analitični izračun brez pomoči računalnika, kot prikaz, kako bi se problema lotili, če za izračun ne bi imeli računalniškega programa. Opravili smo tudi preizkuse različnih obratovalnih stanj. Na osnovi rezultatov segrevanj pri različnih obremenitvah smo določili termično moč generatorja.
Ključne besede: Asinhronski generator, načrtovanje, analitični izračun, meritve
Objavljeno v DKUM: 06.10.2011; Ogledov: 3153; Prenosov: 310
Celotno besedilo (6,14 MB)