A TLM approach for the modelling of high and low frequency EMC problems in power systems

The EMC analysis of complex systems, as the electrified railway where trainset, power supply systems, telecommunication network and train detection and control systems are closely coupled by a variety of mechanisms, requires a detailed knowledge of the internal coupling relationships of the system components. The lack of information preclude any rigorous deterministic prediction of EMI and it requires a test campaigns in order to verify compliance with the limits fixed by international standards on EMI. Nevertheless, the difficulty in carrying out measurement in reproducible way and the cost of a possible system re-design, if a violation of the EM emission is found, suggest the need for a characterisation of EM environment right from the start of the project phase. For this purpose it is necessary, starting from the models of the main noise source and victims, to provide of a methodology capable of describing in an easy way the main coupling mechanisms between the noise sources and the susceptible victims, taking into account both low frequency and high frequency phenomena. On this basis in this paper a new methodology is proposed for the electromagnetic characterisation of the electrified railway systems. In particular a method is presented based on Transmission Line Modelling (TLM) able to model the electromagnetic interaction between electrical circuits which model the sources and the victims of the EMI. A software tool which implements these algorithms is presented and the results of some simulations are discussed