“High quality and customisable, but based on standardised base modules,” is how Frédéric Grizaud, Head of the Offshore Energy Business Unit at STX France, describes the new SeeOs (Scalable Efficient Evolutive Offshore Substation) range launched recently by the Saint-Nazaire-based contractor. The May issue of Mer et Marine Maritime News (see STX France Saint-Nazaire, building offshore substations) highlighted STX France’s commitment to marine renewable energy, specifically the extension and reorganisation of its Saint-Nazaire yard, significant investment in infrastructure and the hiring and training of hundreds of employees. These initiatives follow the booking of several contracts for offshore substations, including a 385-MW unit for German power utility E.ON and a 309-MW one for Belgium’s Rentel windfarm, both currently under construction.
Standardised base module and options
“Since we began working in this field, we’ve submitted bids for 30 or more projects, gaining, along the way, a far better understanding of client needs. We also observed that most could be met by a common core.” This led to the idea of a base module with options for client-specific tailoring. “The next step was to design then launch a product meeting 90% of the market’s needs, allowing us to standardise in-house processes, reduce design and production costs, and, as a result, present lower bids.” The aim, in the Saint-Nazaire tradition, is to move from one-offs to batch production, thereby giving the client the benefit of a proven core product with add-on modules to cater for specific needs.
A fully enclosed 200/300-MW core module
The engineers at STX France’s Offshore Energy Business Unit have designed a fully enclosed 200/300-MW medium-voltage gas-insulated substation, or GIS, complete with transformer and MV switchboard. Two or three of these modules can be assembled to achieve power ratings up to 900MW. “Fully enclosed modules ensure not only higher reliability, but also lower maintenance costs,” adds Frédéric. Client-specific requirements, such as back-up and auxiliary generators, shunt reactors, living quarters, workshops or warehouses, take the form of add-ons.
Thanks to their modular design and adaptability, SeeOs substations can be installed on monopile, jacket or floating foundations, depending on the site. “We are the first in the world to offer this level of scalability.” STX believes that its SeeOs substations will find their place in future floating offshore windfarms. “The basic concept can also accommodate new technologies and requirements, including the anticipated move to 66kV,” says Frédéric Grizaud.
Original by Caroline Britz, translated and adapted by Steve Dyson