ABSTRACT
This chapter explores the issues concerning DC and AC supply systems in use, especially those applied on HSR: 25 kV, 50 Hz and 15 kV, 16 2/3 Hz and 3 kV DC systems used, among others, on Polish railway lines and a 3 kV DC system that is employed in Polish railway lines. The railway power supply system creates a specific electrical energy transmission system in which transport demand requires supply of sufficient quality and quantities of electric energy to obtain a suitable transport output. The system comprises following subsystems: vehicles operating based on a specific timetable, a traction power supply system, to which electric energy is supplied from a power supply network from the electric power system.
The applied power supply traction systems do not actually differ as far as a circuit structure is concerned. In each contact system the electric energy is taken from the source system (electric power grid), then it is converted to transmission voltage, and then converted to the type (direct voltage, alternating voltage at specific frequency) and voltage level suitable to supply trains within a given contact system. Electric trains are mobile consumers supplied from the contact system - return system circuit.
Each currently used HSR power supply system has its specific strengths, weaknesses and limitations. The comparison of specific features and technical solutions of HSR systems – their advantages and drawbacks is presented in the chapter. What forms an important part of the chapter is a description of the requirements for HSR lines supply systems, including those presented in the Commission Regulation (EU) No. 1301/2014 of 18 November 2014 on the technical specifications for interoperability of the “Energy” subsystem.
Due to the 3 kV DC supply system that is used in Poland on 1200 km of electrified lines, particular attention was given to Polish rules and regulations as well as requirements regarding the system. It is resulted from the fact that under Polish conditions, prior to construction of new lines supplied with voltage of 25 kV 50 Hz (planned on Warszawa-Lodz-Poznan/Szczecin line), the highest speed (200-250 km/h) will be reached on E-65 Grodzisk Maz. – Zawiercie and Warsaw – Gdansk lines, where Pendolino trainsets were entered into service in 2014. Distances between Warsaw and major metropolitan areas not exceeding 300 - 400 km indicate that the network of railway lines with operating speed of 200 - 250 km/h should improve competitive advantage of railway transport over road transport and air transport. It required upgrade of the existing system 3 kV DC.
Countries which have recently commenced the construction of HSR lines employ voltage at the frequency of national power grid 50 or 60 Hz as a standard solution. They are not only highly developed countries, but also countries like Turkey or Morocco. It is expected that also in Poland the decision to construct the HSR line with operating speed in the range 300 - 350 km/h shall be made as soon as justified by traffic and transport policy, which would require a 2×25 kV 50 Hz power supply system. The undertaken projects to introduce in Poland this new system take into account specific conditions, such as 3 kV DC railway power supply coexisting with a new 25 kV 50 Hz one, which in turn causes problems of compatibility – mutual influence of both systems and safety, especially in railway nodes. These problems were underlined and discussed in this chapter together with final conclusions regarding further development of HSR power supply in Poland.
