Direct generation of low frequency single phase AC for the Railway in Norway and Sweden

Abstract: This thesis deals with direct generated electricity for the Swedish and Norwegian railway systems. The form of renewable energy sources that are presented in this thesis is hydropower and a small part is about wind power. Älvkarleby hydropower plant could give redundancy to the Swedish railway system and at the same time solve that problem of locations for static converters close to Stockholm since the land areas close to Stockholm are expensive [14]. A conversion of 50 Hz generators into 16.66 Hz generators in Älvkarleby hydropower plant could lower the pressure on the nearby converter stations which this thesis shows, see Table 6.6. The conversion of a part in Älvkarleby hydropower plant would also strengthen the Swedish railway grid as can be seen in Figure 6.11 and Figure 6.12. If a malfunction would happen in Häggvik converter station as the case was in the fall 2008 [35] and Älvkarleby is functioning it would be possible to have train traffic running. The simulation preformed in this thesis shows that it is possible to have reduced traffic and still have the voltage levels in an acceptable range, see Figure A 4.3 and Figure A 4.4. In 2009 the "132 kV power flow control system" will be introduced for the Swedish railway system. This control system together with direct generation by hydropower could make the idea of hydropower generation attractive as one alternative renewable energy source. Both Norway and Sweden have similar railway systems. The 16.66 Hz electricity price is increasing in Norway and that is one reason why JBV (Jernbaneverket, a company that owns the Norwegian railway grid) chose to renovate one of their two hydropower plants that generates low frequency electricity for the railway. The renovation plans show that JBV sees a profit in renovating their existing low frequency hydropower plants. These aspects are strong arguments to why a reintroduction of hydropower in Sweden could be one alternative solution to more static converters, when dealing with the problem of increasing power consumption.