Optimisation of AC feeder topology for a DC supplied rapid-transit railway

The AC feeder network for a DC-supplied railway has a vital role in providing a highly available supply service to passengers on a mass-transit railway. Planning for a cost effective supply power network, while considering availability, is a very complex job. The paper describes a novel technique applicable to the planning of enhancements to an existing AC feeder network or the planning of a new network. The technique optimises the AC feeder network topology and feeder content in order to minimise the whole-life cost of the AC feeder network with two choices of system availability constraint. The choices are either to ensure that the network is secure if any single feeder is removed or to ensure that disruption costs as a result of feeder failure are included in the whole life cost. In the latter case, any additional feeders added to the network need to produce a net decrease in whole-life costs due to a reduction in disruption costs. The technique evaluates the optimum network for each of the two choices. A case study with sensitivity analysis for a part of the Northern Line of London Underground Ltd. is reported