AUSZUG | eb - Elektrische Bahnen INT 2/2015

26 113 (2015) INT 2 Rail Power Supply Analysing frequency components of rail traction current load profile as a function of rail operations Julius Bosch, Zollikofen (CH) The significant load fluctuations in the Swiss Federal Railways (SBB’s) 16,7-Hz rail traction current supply will increase in the future. We can explain these load fluctuations by analysing the charac- teristic frequency components of the overall load profile and analysing them by filtering over time. This shows that, in theory, peak loads can be reduced by adjusting the integrated regular interval timetable. As this is not an option, however, alternatives will be presented here. FREQUENZKOMPONENTEN DES BAHNSTROMLASTGANGS – ZUSAMMENHÄNGE MIT DEM BAHN- BETRIEB Die erheblichen Lastschwankungen der 16,7-Hz-Bahnenergieversorgung der Schweizerischen Bun- desbahnen (SBB) werden künftig noch zunehmen. Werden mit einer Frequenzanalyse charakteristi- sche Frequenzkomponenten des Gesamtlastverlaufs extrahiert und mit Filtern im Zeitbereich analy- siert, lassen sich die Lastschwankungen erklären. Es zeigt sich, dass Lastspitzen theoretisch durch den Eingriff in den Integralen Taktfahrplan reduziert werden könnten. Da dies jedoch nicht diskutabel ist, werden dazu Alternativen vorgestellt. COMPOSANTES SPECTRALES DE LA COURBE DE CHARGE – LES INCIDENCES SUR LE TRAFIC FER- ROVIAIRE Les variations de charge considérables de l’alimentation en courant traction 16,7Hz des chemins de fer fédéraux suisses (CFF) sont appelées à s’accroître à l’avenir. L’extraction des composantes spectrales caractéristiques de la courbe de charge totale et leur analyse avec des filtres dans une plage de temps donnée permettent d’expliquer les variations de charge. Il est démontré que les pointes de charge pourraient être théoriquement réduites par l’intervention dans l’horaire cadencé intégral. Mais comme une telle opération est hors de discussion, l’article présente des solutions alternatives. 1 Introduction As well as its basic day-to-day pattern with its morning and evening peaks, the overall load on SBB’s 16,7-Hz rail traction current supply also fluctuates considerably from 1min, even from one second to the next (Figure  1). These extreme fluctuations pose a challenge to network control. Only by concentrating massively on the use of generating units which allow high power gra- dients, such as Pelton turbine sets, rotating and static frequency converters, we can cope with such major load fluctuations. These fluctuations also make it highly likely that major peak loads will occur, which entail increased investments into the availability of input power. Maximum peak- load power is set to increase in future, as trains become more powerful and the timetable more dense. Anyway, the input power available at any time must be sufficient to cover the network load and to ensure network stability. 00:00 03:00 06:00 09:00 12:00 15:00 18:00 h 00:00 0 100 200 300 400 500 MW 600 t P ges Figure 1: Load profile of overall load of the 16,7-Hz traction power network of SBB of September 4, 2013 (Figures 1 to 6 and 8: author).