ABB has won a competitive tender to secure its biggest ever contract for high-voltage service from First Hydro Company. During the project, ABB will replace one of six GCBs at the Dinorwig Power Station in Wales for $4.5 million. First Hydro Company has also put in place a framework agreement with a view to replacing the site’s other five units by 2028 following success with the first unit.
The new GCB will ensure Dinorwig’s reliability and availability as a power generation station for the National Grid for decades to come. It will also provide certainty for First Hydro Company, which is owned 75 percent by ENGIE and 25 percent by Brookfield Renewable. The site’s GCBs control the flow of power between the generating motors and the power transformers, protecting the high value equipment from electrical faults.
When it was first built in 1984, Dinorwig was hailed as one of the world’s most imaginative engineering and environmental projects. Not only is the plant Europe’s largest pumped storage power facility but it was built to minimize environmental impact by being constructed inside the Elidir Fawr mountain. The site remains the jewel in the crown of pumped hydro-power today. It hosts a visitor centre known as Electric Mountain that gives public access to some of the 16 km of underground tunnels inside the mountain.
When National Grid needs extra electricity to meet peak demand, the site’s operators release water from a high-level reservoir to power six reversible pump turbine units, each of which can reach an output of 300 MVA (MegaVolt Ampere) within 16 seconds. At times of low demand when energy is inexpensive, the generating units are then reversed to pump water back up 520 metres to the high-level reservoir in preparation for the next peak demand period.
Operational savings
ABB supplied the facility’s original GCBs and has delivered regular maintenance services ever since, including testing and providing spare parts. However, the time has come for First Hydro Company to replace the time-served unit with
the latest state-of-the-art circuit breaker technology in the form of ABB’s HEC130 GCBs. The new breaker will offer the advantages of a long and reliable lifetime and reduced maintenance requirements. Whereas the existing air-blast circuit breakers require an overhaul after every 3,000 operations, the new HEC130 unit will only require overhaul after 20,000 operations or 20 years.
The cyclical nature of pumped storage means that the GCBs at Dinorwig are required to operate more frequently than at baseload power stations. As a result, the existing units require a high level of maintenance, with Dinorwig’s own in-house team carrying out the majority of the work and calling in ABB for testing before returning the units to service. Longer maintenance intervals will mean that the new GCB will be a source of significant operational savings.
Real-time digital insight
During the replacement project, First Hydro Company is taking the opportunity to integrate the new GCB into its asset management ecosystem via the ABB Ability GSM600 monitoring system, which will provide real-time digital insight into the health and status of the unit.
Compact with integrated instrument transformers
Each of Dinorwig’s six GCB units is made up of three individual phases that are housed inside busbar galleries deep inside the mountain. Each gallery houses three single-phase GCBs as well as Current Transformers (CTs) and Voltage Transformers (VTs), which are used for measurement, as well as lengths of busbar, braking switches and earthing switches.
To deliver the replacement of the first GCB, ABB will completely dismantle and remove all equipment in the busbar gallery before engaging local contractors to refurbish the gallery and install new lighting. ABB will then install brand new equipment. One benefit of modern HEC130 units is that they house three phases in a single unit, therefore the new layout will be significantly smaller. In addition, the HEC130 integrates CTs and VTs so there will be no need for external instrumentation.
Twelve-week outage
One significant challenge during the 12-week outage will be the logistics of lifting out old assets and dropping in new equipment through a restricted access shaft that measures four by two metres. To achieve this, ABB has created a detailed work programme to ensure that it completes the replacement within the allowed time and avoids any financial penalties that could otherwise arise if the power station was not available to National Grid at the end of the outage.
With lifting operations being essential to success, ABB’s service team is planning to provide standby winches to guarantee that lifting operations will continue without interruption. While it is planning for 12-hour working days, the team can extend to 24-hour working and can call in additional resources if required as there are no restrictions on working hours inside the power station.
Dave Dewitt, Manager for High Voltage Service, UK, said: “Winning the contract to replace the first GCB unit at Dinorwig is a milestone service contract for ABB, as it is our largest ever UK service contract. It builds on our success in similar projects, including replacement of time-served GCBs with HEC130 units at Heysham and Hartlepool for EDF Energy in 2016, as well as our excellent working relationship and experience with First Hydro Company.”
