25 kV harmonic resonance modelling on channel tunnel rail link

The channel tunnel rail link is an ac electrified railway with a fundamental operating voltage of 25-0-25 kV utilising autotransformers. The principal electric traction that uses this new rail link is the class 373 Eurostar train; other Rolling Stock will eventually use the CTRL. The RLE safety management plan a rigorous risk assessment programme that has been undertaken for all aspects of the new railway, this also includes electromagnetic compatibility (EMC). During the hazard analysis the risk of harmonic resonance was identified. Harmonic resonance was a credible risk to the reliable and safe operation of the completed CTRL, however it was also found that it was very difficult to quantify the risk. RLE examined the possible impact of resonance on the construction programme and concluded that it could severely disrupt scheduled passenger service and that the lead time to resolve the problem would be long. RLE decided to commission AEA Technology to produce a resonance model which would allow RLE to determine the level of risk and, in the event that the resonance was found to be a high risk, use the model to reduce the time required to devise suitable mitigation measures.