RETROFIT. AND THE ELECTRICITY KEEPS FLOWING.
Allgäuer Überlandwerk GmbH quite literally operates a substation "where the green grass grows" in the Zell city district of Oberstaufen, Germany. For 15 years, the substation has connected the network of this German energy supplier to the Voralberger Kraftwerke AG network in Austria. New phase-shifter components and the expertise of MR now ensure that the proven and mutually productive cooperation between the companies will continue into the future.
It is not just people who create busy cross-border traffic between the German Allgäu and the Austrian state of Vorarlberg because they appreciate the advantages of the two neighboring regions. A constant flow of electricity crosses the border as well. Allgäuer Überlandwerk (AÜW), for example, obtains cost-efficient energy from Vorarlberger Kraftwerke (VKW) to supply private customers and companies in Westallgäu with power. Since the late 1990s, a phase-shifter transformer with an output of 80 MVA has been controlling this energy exchange at the AÜW substation in Zell reliably and without any notable malfunctions. To increase maintenance intervals and enable the phase shifter to handle increasing demands, AÜW gave it a "facelift" - with MR`s help - as part of extensive retrofitting measures.
Allgäuer Überlandwerk and Maschinenfabrik Reinhausen have been working together for decades. For this reason, the phase-shifter transformer at the substation in Zell has been equipped with MR components since its initial commissioning. "We have established a very trusting relationship over the years," says Engelbert Sommer, Team Leader of Maintenance at AÜW. Logically, when awarding the contract for the comprehensive modernization, the company also chose to put its trust in the expertise and service of MR in all matters related to technology and project management. Only eight months passed between the awarding of the contract in early 2015 and the re-commissioning of the phase shifter in August.
The priority of the retrofit project was to replace the two on-load tap-changers for the in-phase and phase-shifted regulation. New state-of-the-art VACUTAP® on-load tap-changers with vacuum technology now operate in the place of the previous tap changers with conventional oil switching technology. The replaced phase-shifted regulator had switched reliably more than 800,000 times with standard maintenance intervals. "Since the phase angles of the AÜW and VKW networks are constantly changing, it was subjected to a great amount of stress," explains Sommer. "Thanks to the vacuum technology which has now been introduced, we can achieve a significantly higher number of tap-change operations at extended maintenance intervals. This reduces operating costs and increases transformer availability."
Moreover, a newly installed TAPCON® voltage regulator with ISM® technology has taken over all control and regulation tasks and three TAPMOTION® ED motor-drive units, which have also been newly installed, ensure safe and reliable operation of the tap changer and the de-energized tap-changer.
The drives and voltage regulators were extensively tested under real-world conditions at MR's high-technology test center in Regensburg (Germany) prior to the retrofitting process. The Factory Acceptance Test (FAT) was also carried out subsequently in Regensburg in cooperation with AÜW. During the commissioning in Zell, the regulation and interaction of the entire system was jointly accepted with AÜW and approved by the MR specialists. "Also in regard to this comprehensive modernization process, we were once again very satisfied with the professional consultation and implementation," concludes Sommer.
RETROFIT: SOLUTIONS FOR A LONGER SERVICE LIFE The maximum service life for power transformers used to be 40 years. Today, some achieve a service life of more than 60 years. After a certain period of operation, it may make economic sense to replace components such as on-load tap-changers, drives, measurement and regulation technology or cooling systems. Where desired, Maschinenfabrik Reinhausen retrofits entire transformers with maintenance-free components. MR does this by combining all services into a total package and also by assuming the entire project management for its customers.
"Service and retrofit" brochure as a download