I början av 1800-talet började järnvägsnätet i delar av Europa elektrifieras. Då klarade inte motorerna att kommutera vid nätets höga frekvens, 50 Hz, då omformades istället frekvensen till 16,7 Hz. För att växla frekvensen användes roterande omformare. Senare kom mobila omformare som stod på järnvägsvagnar. Dessa omformarstationer var ofta placerade i bergrum. Nu på senare år har tekniken utvecklats och roterande omformare har ersatts med statiska omriktare. Balfour Beatty Rail AB har utvecklat en typ av mobil statisk omriktare som ökar mobilitet samt att stor del av kontroll före idrifttagningen kan utföras i fabrik vilket sparar tid vid idrifttagning av stationen. Ett byte från en mobil roterande omformare till en mobil statisk omriktare i en bergsstation har inte tidigare utförts. Denna förstudie syftar därmed till att ge en beskrivning på vilket sätt en mobil statisk omriktare kan installeras i en befintlig station. För denna studie har Asker omformarstation valts då den är en typisk omformarstation placerad i ett berg. Asker station innefattar tre roterande omformare med en total märkeffekt på 30 MVA. Omformarna förser järnvägen med 15 kV 16,7 Hz från ett 22 kV 50 Hz nät. Asker omformarstation har en begränsad uppställningsyta både inne i bergrummet samt utanför. Det är norska Jernbaneverket som är innehavare av stationen. Studien avser även att kontrollera effektbehovet från Asker station. För att uppskatta effektbehovet utförs simuleringar vid höglastperiod. Simuleringsresultaten används även för att utföra ekonomiska kalkyler i form av LCC-kalkyl samt återbetalningstid med hjälp av pay back-metoden. Två ekonomiska kalkyler har utförts, en kalkyl med restvärde på de omformare som ersätts samt en kalkyl där restvärde av omformarna inte tas i beaktning. En uppgradering där statiska omriktare ersätter roterande omformare skulle i Asker station leda till oförändrad installerad effekt, då platsbrist medför att de tre roterande omformarna inte kan ersättas med fler än två mobila statiska omriktare. De minskade förlusterna medför en vinst om ca 2 miljoner NOK per år. Ett restvärdeskrav kan ställas på de tre roterande omformarna på minst 51,5 miljoner NOK för att uppnå en ekonomisk lönsamhet / In the beginning of the 19th century the railway in Europe was electrified. The engines of that time were not able to commutate at the high frequency of the grid for electric distribution, 50 Hz. This problem was solved by installing rotary converters that changed the frequency to 16.7 Hz. Nowadays static converters has replaced rotary converters to change the frequency in many stations. Balfour Beatty Rail AB has developed a mobile static converter system that makes commissioning tests possible to do in an earlier stage at the manufacturer. This testing minimizes the time spent on site for installation and startup. This bachelor’s thesis is a study that covers if it is possible to exchange a rotary converter with a static converter for railway use and how such a change can be made, mechanically and electrically. For this study Asker converter station in Norway 20 km west from Oslo has been chosen for a case study. Asker is a station that has three rotary converters of the largest type used for electrifying the railway at 10 MVA each. The rotary converters supply the railroad with a 15 kV 16.7 Hz voltage from a 22 kV 50 Hz grid. Asker is a station which is placed within a mountainside. This is a standard type of installation for a rotary converter station. Asker station has a limited area both inside and outside the station. Asker converter station is owned by Norwegian Jernbaneverket. The static converter station must be powerful enough to handle the load of Asker station. This load is simulated by using the timetable of a high load-period. This study also has the purpose of providing an economic view of the exchange since a static converter has a lower energy-loss than a rotary converter which could lead to an economic gain for the owner of the station. In Asker station the three rotary converters will have to be replaced by two mobile static converters because of the stations limited capacity. From the lowered losses a gain of 2 million NOK per year can be made. If the residual value of the three rotary converters can reach 51.5 million NOK it will lead to an economic viability

The number of solar panel systems and electric vehicle charging in the low voltage grid is increasing rapidly, due to climate- and environmental targets. These nonlinear loads inject harmonics into the grid, which could impact power quality as well as the wear and life of power grid components, such as transformers and cables. The Swedish network operator Ellevio wants to investigate the possible effects that can arise from a largescale introduction of this equipment in the grid, in terms of harmonics. The aim of this master thesis has been to evaluate the compatibility of equipment emission standards and requirements for power quality, and through different calculation methods assess the potential impact from high penetration of devices in the same network. The results show that converters of both EV and PV are able to keep emission levels well below the equipment standard limits. Even by full penetration of a network the aggregated effect of these loads will not alone have a significant impact on neither power quality nor components in terms of wear, losses or capacity. However, in networks experiencing unusually high background levels in combination with high emissions from other loads, the PV and EV emissions could be a contributing factor to a state where individual transformers would be affected or single harmonic voltage limits would be violated. This is considered a very rare case, and thus not something that would serve as a basis for the dimensioning of the low voltage grid. Instead, increased knowledge will help assessing such a scenario and give better support for solving the individual cases that do arise.