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5 Uppsatser om Tap-changer - Sida 1 av 1
Acceptansgränsen för solceller i lågspänningsnät : Kan den ökas?
Microproduction, also called distributed generation, is something that has become more and more popular in the electric grid. Microproduction can however lead to unacceptable performance if several units are installed in the same low voltage network. It is therefore good to know a limit where the performance of the low voltage network becomes unacceptable based on given parameters. This limit is usually called hosting capacity.In this report the hosting capacity with respect to voltage and current have been studied in three low voltage networks which are located in Falu Elnäts concession area. This has been done by simulations in a GIS-program where critical times of the grid have been simulated.
Reklam för Responsiva Webbplatser : En studie i hur reklam bör utformas för internet
Advertising in responsive websites is a quite new phenomenon and has therefore, previously not been a target for any mayor research. Todays society, where new technological innovations persistantly supersede others must be seen as a possible changer for how companies advertise to this society. This paper sheds light on many of the difficulties connected with advertising for responsive websites, but also possibilities and advices for the future. Through a litterature review and a focus group with respondents from a large communication agency in Umea?, insights, implications, solutions and thoughts both connected to specific websites but also around advertising for the future as a whole is presented.
EU som global politisk aktör - En utvärdering av Normative power Europe
What kind of international actor is the European Union and how shall we define it? These are questions that many have tried to answer often by addressing the apparent uniqueness of the EU itself. One of these theories is Normative power Europe. A theory whose main argument is that the EU is best perceived as a changer of norms. My aim with this thesis is to test this claim and to see if the Union should be regarded as a normative power.
Utredning av variablerna som påverkar storleken på brytspänningen i lindningskopplare
Brytspänningen är den spänning som uppkommer när överkopplingsmotståndet i lindningskopplaren lämnar sitt föregående läge vid omkoppling. Storleken på brytspänningen i lindningskopplaren beror på hur stor läckinduktansen är. Är den inte känd så kan brytspänningen istället beräknas med hjälp av FEM-programmet ACE (internt ABB-program) i samband med Mathcad. I ACE beräknas först reaktanserna i p.u-enheter mellan lindningarna och hur stora de är beror på lindningslayouten. Det är tidskrävande att använda ACE och Mathcad och uppgiften är att utreda de parametrar som påverkar storleken på brytspänningen samt att ta fram en förenklad beräkning av densamma.Genom simulering i ACE av en mängd olika lindningslayouter visar det sig snart att det är alltför många parametrar som påverkar reaktanserna.
Analys av spänningsstabilitetsberäkningar i det svenska elsystemet
Numerical simulations play a vital role in both static and dynamic stability assessment of electric power systems and the foreseeing of voltage collapse. Simulations performed by Svenska Kraftnät(SvK) are mainly done in the specialized voltage collapse predicting software tool, SPICA and the more all?purpose software tool, ARISTO.The grid operators at SvK use SPICA to predict the maximum transfer limit at specified sections (in this report the section in concerns is the southern part of Sweden i.e. interface1 4). SPICA is mainly used as an online application by using actual states from the grid, these states update every quarter of an hour.This thesis is a continuation of the master thesis SPICA ? ARISTO JÄMFÖRELSE by Jakob Katzman and Johan Fält.