Power supply of trams in Poland – current state and perspectives of development

Sustainable development of agglomerations requires efficient and ecological transport systems, i.e. electrified transport. In order to achieve the required results of operation of electrified urban transport, especially energy efficiency, it is required to closely examine the existing power supply systems. The biggest share of urban traction systems in Poland belongs to tram systems (in 15 agglomerations and cities). Recent years have witnessed an increased interest in modernisation of the existing lines and construction of new ones. Enhancement of RAMS (Reliability, Availability, Maintainability, and Safety) and energy efficiency of supply systems is a necessary requirement, due to fact that new, modern tram rolling stock with higher power poses significant challenge for the existing, in many systems, old power supply infrastructure. Furthermore, due to low driving-range of autonomous vehicles equipped with batteries and a need of frequent charging of storage devices, catenary supplied urban transport will dominate in the areas of its use. In addition, it might be helpful in developing hybrid vehicles supplied both from a catenary and from energy storage devices (charged during run under catenary) on sections without catenary. The paper presents parameters characterizing tram power supply systems in Poland. The analyses carried out for many tram lines have shown that even at relatively low investments for modernisation of the tram power supply system, it is possible to obtain fast return (energy saving due to improvement of efficiency of recuperation and the resulting reduction of CO2 emission). Other advantages of modernisations include: enhancement of standards in supply of modern trams with higher power and improvement of reliability due to the reduced risk of disturbances and damages