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At 576MW, the Gwynt y Mor wind farm off the north Wales coast will be the second largest offshore facility in the world behind the 1GW London Array. To make sure the operation runs smoothly, developer RWE is building a dedicated operations and maintenance (O&M) base at the nearby port of Mostyn. The facility is currently still in installation mode but will be ready by the time Gwynt y Mor becomes fully operational in 2014.

Unlike some of the offshore projects planned for the third round of leasing in UK waters, Gwynt y Mor is relatively close to shore, with its furthest point around 11.5 nautical miles from land. Proximity to the project was the main deciding factor for setting up the maintenance base at Mostyn, to the east of the site. It is the nearest point of access for crew transfer vessels (CTVs), taking under an hour to reach the wind farm.

Keeping the trips to a minimum remains a priority, however, for operations and maintenance manager John Porter. His mantra by which he measures all decisions - and the key to running a successful and efficient O&M regime — is "doing the right job right first time", so he is confident that his crew will not be making any more visits than absolutely necessary.

Porter's experience as engineering manager of a 2GW coal-fired power station has helped him to develop the processes and systems for maintaining Gwynt y Mor's 160 Siemens 3.6MW machines - a scale of operation requiring a different approach from managing RWE's existing North Wales projects of North Hoyle and Rhyl Flats wind farms at 60MW and 90MW respectively.

Synergies with these projects are an added benefit. The team working on the smaller projects can share technical knowledge, storage facility, CTV charter and a pontoon facility, all of which helps to reduce costs.

Major task

"Depending on the weather and the task, it will usually take three technicians three days to complete the 500 hour service and circa ten days for the annual service of each turbine," says Porter. "When there are 160 turbines, and you subtract the number of days when it is impossible to access the turbines, it can be a struggle fitting them in. There are also other activities that need to be allocated time, such as six-monthly insurance inspections and equipment inspections."

Porter admits that there are always some maintenance needs that come out of the blue and, much as he hates to say it, those are usually the most exciting and challenging parts of the job.

Location, location, location

Access into the field is key in reducing costs, says Porter, explaining the importance of the O&M facility's proximity to Gwynt y Mor. Service operations vessels (SOV) with accommodation are not used because of proximity to the field, explains Porter. All the RWE technicians live nearby. "The majority of technicians who can see their house while they are stuck out on an SOV would prefer to go home. They come into their own when technicians are more than two hours from shore, but under an hour makes going home by far the preferable option," Porter says.

Porter employs 37 operations and maintenance staff, or more than 100 when you include local technicians working for Siemens. This is consistent with a similar-sized gas-fired power station, he says. The RWE technicians work in rotating eight-week patterns, alternating between manning the control room onshore and working offshore.

Monitoring

At over 100MW, Gwynt y Mor is classed as a large power station, and to comply with the grid code, requires a separate control point. While nearby Rhyl Flats and North Hoyle, with 132kV grid connections, are monitored by RWE's control room in Swindon, the company has taken the decision to create a high-tech control room at Mostyn to monitor Gwynt y Mor's 400kV grid connection. It will be equipped with remote diagnostics and alarm systems for the grid connection, the offshore platforms and the wind turbines themselves, and the power will be fed from the new substation at nearby St Asaph.

At the moment, marine co-ordination also takes place out of the control room. The continuity of a 24-hour operation means that each day can start with all equipment in exactly the right place: "The equipment will be prepared the day before, but this means that no matter what happens overnight, crews will not be delayed in getting to the field," he says.

Porter is pleased with the calibre of his recruits, being able to choose the "cream of the crop" — no less than 176 candidates applied recently for ten posts. He looked wider than just experience as wind technicians: "You can't have a good football team if they are all Wayne Rooneys." The final team members come from a variety of disciplines, including a local aluminium works that has closed down, power stations and a nearby RAF base.

In future he will be able to recruit from apprentices who have taken the three-year RWE wind-specific turbine technician course at nearby Llandrillo College that started last year.

In addition to appointing skilled staff, Porter acknowledges the importance of investing in the equipment his team will use. This is why RWE is developing a technique for Mostyn similar to that used at airports to dispatch luggage to the aircraft.

RWE has designed specialist lifting cases so that all the spares, tools and equipment needed for a job will be loaded from stores the night before, loaded and held on special electric trucks with trailers, which are then transported to the pontoon, where they are loaded on to the transportation vessels. At the wind turbine, the containers are then lifted on to the wind turbine so that all the equipment is in place for the technician.

During working hours, Porter aims to cut personnel transit time. "We are making the process as efficient as possible so the time spent messing about on land, when they are not actively giving me what they are employed to do is cut to a minimum," he says. The base has been designed so that technicians arrive in their civilian clothes. They pass through a first changing area to change into work clothes, then move into a second area where they pick up the offshore weather gear including immersion suits, waterproofs and climbing gear. They then pass through to the crew departure lounge and wait to be called to the vessel for boarding.

RWE has modelled many different methods of transferring crew. "The fastest vessels wouldn't necessarily give us the best access on to the towers. They might be the fastest vessels, but the most uncomfortable ride. If a technician has been thrown about in transit, the last thing he wants to do is climb up a wind turbine." Porter is exploring vessels up to 24m long to give greater access to the turbines in higher wave conditions. The CTVs carry about 12 technicians and the expected number required will be between six to eight for standard work activities.

Learning in advance

The O&M team is in a unique position to benefit from lessons learnt at Rhyl Flats and North Hoyle. Additionally, as lead contractor for the construction of Gwynt y Mor, RWE technicians can be involved in the commissioning process, and can learn the wind farm intricacies from day one. A year ahead of the handover, the O&M team is already working with the project team and is providing services on the transition pieces where maintenance is needed. When the assets are handed over to O&M, the regime is already up and running.

Porter believes that the facility will be able to deliver maintenance regimes to more projects in the future. "The size and scale of the site we have developed gives us options," he says. "The footprint of land that we have leased gives us as much flexibility as I could ever crave. We are not limited on land size or restricted on building size. We've got the ability to change and adapt."