Endesa has completed the project to improve the power generation plants in the Canary Islands and Balearic Islands, with an investment of 7.6 million euros, to guarantee plant availability in the event of a failure in the main transformers. The company has taken part in the design and development of 11 main output poly-transformers, which can be used as strategic units shared between the entire thermal and diesel plants located in the Canary Islands and Balearic Islands.
One of the aims of the project was to replace a maximum number of existing output transformers with the fewest number of poly-transformers possible. To achieve this, the transformers have been designed in such a way that they can be assembled in different configurations, thus ensuring the 11 units can replace any of the 115 different types of generator units in the event of a failure (including coal-fired units, diesel engines, combined cycles, gas turbines or fuel-oil units).
This improvement will enable Endesa to increase the number of units covered by a compatible replacement from 16 percent to 90 percent (85 percent in the Canary Islands and 98 percent in the Balearic Islands). This guarantees the availability of all the units in the event of a transformer failure, an essential plant component used to evacuate generated power.
A failure in a main output transformer can result in downtimes of more than a year for the relevant generation unit. The main aim of the project is to minimise the periods of unavailability of the units as much as possible, thus ensuring a better-quality supply in isolated systems with the subsequent benefits for end customers.
Another important advantage of the project is to be able to generate cost savings for island systems in the event of a failure in any of the existing transformers. Having the new transformers guarantees that power is always generated using the plant's most efficient units, thus avoiding having to use other units with greater costs for the system.
Given the large variety of units in the plants in the Canary Islands and Balearic Islands, given the each island’s characteristics, the power ranges of the poly-transformers have been adapted to the size of the units from 2 to 162 MVA (mega-volt amperes), while transformer ratios have been determined according to the voltage levels of the distribution and transmission grids of each island going from 20 to 230 kW (kilowatts).
The project, which has been developed over three years, was an engineering challenge in terms of the design of the poly-transformers, given the need to be able to guarantee full electrical and mechanical compatibility with the different equipment they may have to replace. The design phase unearthed and addressed a number of very different technical factors given the extreme complexity of the existing installations.
Endesa has collaborated with the manufacturers in the different design phases in order to find the simplest and most reliable mechanical, technical and electrical solutions for each site. The poly-transformers are equipped with various sets of terminals and adapters that enable the installation thereof following multiple assembly positions as well as different electrical connections required in order to adapt the internal wiring with the machine windings.
During the poly-transformer design and engineering phase, including in-factory inspections, around 14,300 hours were invested by Endesa’s own personnel and various manufacturers, which is testament to the complexity of the project.
Contracts to develop the equipment were awarded to four manufacturers with proven engineering and design skills in order to address the project’s requirements and conditioning factors. The delivery deadline for the transformers varied according to the size thereof, running from seven months for the smaller ones t a year for the larger ones or those that required longer engineering phases.
The project also included construction work in order to adapt the bedplates for the storage and long-term conservation of each of the poly-transformers in the various plants, and trays were purchased to collect oil in the event of a leak from any of them. More than ten companies were called in.