ABB technology to address overhead wire voltage drops

Capacitive compensation technology will prevent voltage drops along the overhead wires that supply the power to Eurostar trains.

ABB has secured a major project with High Speed 1 — the organisation that owns the assets of the Channel Tunnel Rail Link and develops and maintains the infrastructure — to design, manufacture and install the capacitive compensators to prevent voltage drops along the 25kV supply serving the 68-mile (109km) High Speed 1 route from St Pancras International to the Channel Tunnel at Dover.

High Speed 1 is used by Eurostar trains operating the international high-speed routes between London, Paris and Brussels, as well as high-speed domestic trains that provide a commuter service between London and Kent. The railway lines are electrified on the 2 x 25kV principle using autotransformers.

Although High Speed 1’s nominal line voltage is 25kV, there are some areas of the line where it can drop as low as 17.5kV due to the design of the power-hungry isolation transformers (used to isolate between High Speed 1’s AC traction power supply and the adjacent Network Rail DC traction power supply), which are located in the existing substations along the line.

A number of studies commissioned by High Speed 1 demonstrated that a reduction in the power demand from the isolation transformers will improve system performance. This will be achieved by the installation of ABB’s capacitive compensation equipment that will effectively cancel out the inductive power demand of the transformer, and hence reduce the voltage drop.

ABB’s contract with High Speed 1 covers the design, manufacture, installation and commissioning of the capacitive compensation filters in nine AC/DC compounds at strategic positions along the line.

Seamus O’Neill, ABB Power Systems operations manager for rail said: ’ABB will address the existing issues with voltage drops, ensuring the efficient operation of high-speed trains through London and the Kent countryside to the Channel Tunnel.’