Power electronics broadens scope of HVDC

Alstom Grid’s MaxSine building was officially opened on 23 May at an event that also celebrated 50 years of HVDC expertise in Stafford, under various owners.

Speaking at the celebration, Dr Tom Calverley, founding managing director of what was then English Electric’s HVDC business, described how in the early years the company worked with its main rival AESA to develop the market through a combination of technical cooperation and commercial competition, by assuring potential customers that they would not be locked in to a single supplier.

Today the Stafford site is Alstom Grid’s global centre of excellence for HVDC, a market that is estimated to be worth around£50 bn worldwide between now and 2020.

Stephen Burgin, Alstom UK Country President, said: “Stafford is just one of three sites in the world to produce this new VSC technology.

With planned investment over the next 10 years of over £110bn to upgrade UK power generation systems and infrastructure, the development of new, highly innovative technologies to meet legislative emission targets, has never been more important.”

The new state-of-the-art facility will shortly house the manufacture of VSC (Voltage Source Converter) valve modules, initially for a Swedish project announced at the end of 2011.

Svenska Kraftnät’s 1440MW South-West Link will connect Barkeryd in central Sweden to Hurva in southern Sweden.

Under the terms of the £200m contract, Alstom will supply HVDC converter stations at both ends, as well as control and protection, converter transformers, switchyard equipment, construction and project management.

The South-West Link project is due for completion at the end of 2014.

VSC technology is a relatively new way of generating a good-quality waveform from a DC voltage source using banks of power electronics (IGBT) modules assembled from standard components, together with sophisticated control algorithms.

The system controls both real and reactive power.

Dr Norman MacLeod, technical marketing director for HVDC, explained: “We call it modular multi-level converter technology.

“We adapt the number of modules to the DC voltage that is the optimum solution for a particular scheme.”

Last year Alstom Grid inaugurated a 24MW VSC demonstrator at its R&D centre in Stafford, which acts both as a showroom and a development laboratory where innovations can be tested.

One of the big areas of application will be in renewable energy, MacLeod said, particularly for offshore windfarms in places like the North and Baltic Seas.

“The footprint is small, making it well adapted for offshore platforms.

“We can transport the electrical energy through DC cables, which is much more efficient than AC transmission, and when we come ashore we can connect into the existing grid with this technology even in parts of the country where the AC grid is relatively weak.”

The company is recruiting more than 100 additional engineers and support staff at its Stafford site.

Burgin said: “Alstom Grid in Stafford has a pedigree of 50 years of brain power and expertise and our success is undoubtedly down to our people.

“They are fundamental to our reputation as a solutions provider and a technical leader in this growing global market.”

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