Ice Mechanism And On-Line Anti-Icing Technology For Catenary Of Electrified Railway

In China, the total mileage of electrified railway is growing rapidly, and passenger dedicated lines and heavy haul railways are under large-scale construction. Some newly built electrified railway lines maybe cross the cold, high humidity and high altitude areas where icing disasters occurred more easily. Problems caused by catenary icing have attracted widespread attention at all levels. Both eliminating icing and guaranteeing traction power supply should be achieved, therefore on-line anti-icing technology for catenary will be one of the key technologies to guarantee railway safe operation, on which basic theoretical research need be carried out urgently.In this paper, some key basic factors for catenary icing caused by air moisture were studied. Airflow computation modules for contact wire, messenger wire and complete set of droppers were built on the basis of fluid mechanics and thermodynamics. Then water droplet trajectory was calculated by water droplets force analysis and the equation of motion, thereby enabling an evaluation of the local collision efficiency and the overall collision efficiency. These will be used for ice acceleration studies and the dynamic thermodynamic analysis.The heat balance process and accretion mechanism of ice coating on catenary were analyzed, and the heat balance equation was built after the velocity distribution of the airflow field around catenary and the collision efficiency of water droplet were obtained. The critical anti-icing current for catenary in various operation modes were calculated by means of deriving heat balance equation and analyzing Nu distribution. Based on simulating the icing process in dry growth and wet growth, the icing amount variation was studied.Electrical parameters were calculated in catenary online anti-icing process, in which reactive absorption and sending generated large current. An on-line anti-icing technology used static var generator (SVG) for catenary along railway was proposed. The comprehensive distribution of the anti-icing current and load current were analyzed in direct power supply system (including parallel operating in the end) and AT power supply system (including parallel operating in the end). Based on the voltage limitation of traction power net, the dynamic range of anti-icing currents were calculated under different operating conditions.The key processes that have influence on ice acceleration rate such as collision efficiency of water droplet, heat balance equation have been analyzed. The relationship of catenary current distribution and voltage of traction power net also has been obtained. These were used for the dynamic control of the catenary anti-icing current and anti-icing system. Two decision-making modes which treat catenary temperature and iced strength as control objective were proposed. The icing amount variation, catenary temperature fields changing with time and distances to substation were calculated when online de-icing system running. Those results and analysis indicate the correctness and feasibility of the on-line anti-icing method using SVG.