Five ABB Static Var Compensators (SVCs) and 10 harmonic filters have been installed in critical points of the London Underground 22 kV distribution grid:
Completion of this project now enables London Underground to draw all its power from the National Grid, and has facilitated the recent closure of its ageing Lots Road power station.
ABB – a Voltimum Founder Member company - working within the SEEBOARD Powerlink PFI consortium, has completed a £23 million project to design and install specialist equipment to improve the quality of the electricity supply feeding the entire London Underground Distribution Network. As a direct result of the project London Underground is now able to draw all the power required for all of its surface and underground trains from the National Grid, which is a considerably higher reliability source, and this has facilitated the closure of the old Lots Road power station, Chelsea.
Planned closure of the famous Lots Road power station:
In 1998, London Underground signed a 30 year Private Finance Initiative (PFI) contract with SEEBOARD Powerlink - a consortium formed by EDF Energy, Balfour Beatty and ABB - to manage, maintain, develop and finance London Underground's power supply system. A key element in this scheme was the planned closure of the dedicated 180 MW Lots Road power station with London Underground taking all its power from the National Grid, via London's local Distribution Network Operator, EDF Energy.
Discussions with EDF Energy identified that the additional traction load on the local distribution network, due to the diode rectifiers which feed DC electricity to the trains, would have an adverse effect on the power quality for the London area unless corrective action was taken.
Awarded to ABB:
A £60 million 'Power Quality' variation to the original PFI contract was agreed and the majority of the specialist work was awarded to ABB who carried out a series of extensive studies of the existing electrical system. These studies checked the potential for harmonic distortion and voltage fluctuation under all credible, different, power supply network variations likely to be encountered. It then went on to ascertain the nature and size of the power quality correction installations needed to ensure that London's public supply quality remained within the levels set by national and international norms.
Following the study, ABB installed a total of five Static Var Compensators (SVCs) and ten stand-alone Harmonic Filters in critical points of the London Underground 22 kV distribution grid.
The most complex:
Stephen Trotter, General Manager of ABB Power Systems Projects Division, said: "The ABB equipment has been optimised to smooth load fluctuations and reduce harmonic disturbance on London Underground's two power distribution networks, at 22kV and 11kV, which provide power to 158 delivery points. The size of the London Underground, which serves 270 stations and over 250 miles of track, combined with the nature of the train loads - with large numbers accelerating and braking at any one time - made the project one of the most complex reactive power compensation studies ever undertaken.
"Previously, London Underground generated its own power to supply the sub-surface railway and drew additional supplies via EDF Energy to feed the surface railway. Successful completion of the project now enables London Underground to draw all of its annual 900,000 MWhr power requirement from EDF Energy."
The 22kV transmission and 11kV distribution London Underground power supplies are converted by local transformer rectifiers to provide 630V DC (750V DC in future) for the train motive power. The transformers also provide lower voltage supplies for lighting, lifts, escalators, ticket barriers, communications and control systems and so on.
Contact: Karen Strong
ABB Power Technologies
Tel: 01785 825050
Email: [email protected]
Web: www.abb.com