First 1,500V Hesop advanced reversible substation put into service

The use of Alstom’s Hesop reversible substation, the first Hesop 1,500V 4MW, is set to help make ATM (Azienda Trasporti Milanesi), Milan’s subway operator, more energy efficient and also help control tunnel temperatures. It is the second Hesop in commercial operation on a subway line, the first being the Hesop 600V 1MW, provided by Alstom, installed for the London Underground.

The Hesop system works by converting and transferring any unused power, generated by the trains during braking, to accelerating trains elsewhere on the line or to the grid. The Hesop control system is highly intelligent and ensures that the energy is recovered via the most efficient route that the infrastructure permits. It enables the recovery of more than 99 per cent of the traction energy generated during braking, thereby reducing CO2 emissions through reduced energy consumption. The system allows ATM on the Yellow Line to recover 15 per cent of the traction energy generated when trains brake, and then to re-inject that energy into the public power grid.

“This is fantastic news for us, for Milan Underground, for commuters and for the environment. We bring our innovative technology with the introduction of Hesop in the Rogoredo sub-station of Yellow Line of Milan subway,” said Michele Viale, Managing Director of Alstom in Italy and Switzerland.

The project was developed jointly by Alstom’s site in Rome, Italy Charleroi, Belgium and Saint-Ouen, France for ATM. The Milan subway operator played a key role in the project by making a proofing environment available and sharing the installation solutions in the project phase. 124 Hesop substations have been sold by Alstom so far for the projects of Desio-Seregno tramway and metro, London Underground, Riyadh metro, Sydney tramway, Panama and Dubai metros.

“ATM is always interested in participating in innovative projects that allow greater energy efficiency and a lower environmental impact. This is another piece in the ATM policy towards a zero-emission company” said Miles Parisi, Energy Manager ATM.