Experiences & Innovative Repairs on GVPI Generator Stator Windings
(Room Nile 3)
19 Sep 17
4:00 PM
-
5:30 PM
Tracks:
Track C - Optimizing Plant Operation
One of the best synchronous generator equipment manufacturer responses to the global & Asian energy market needs during the last decades has been the adoption of the Global Vacuum Pressure Impregnation (GVPI) technology, a process by which a fully wound generator stator is completely submerged in resin. With this technology, one achieves a highly reliable winding, no looseness of the stator core, corrosion proofing, prevention of coil vibration, improved cooling performances, and the elimination of wedge replacement A properly GVPI winding will have superior characteristics to a conventionally manufactured generator stator, supporting a longer, more reliable and more maintenance-free life span. However, with the rapid introduction of sporadically available renewable generation especially in Asia, power plant generators are now often exposed to a much more onerous cyclic operating profile. Full utilization of IEC/ANSI temperature limits, shorter starting cycles, more frequent starts and stops, longer turning gear operation, more frequent and sharpened load changes are some of the new demands which expose the generators to additional stresses and, as a consequence, accelerating the component fatigue and aging. These factors, sometimes in combination with improper maintenance protocols can lead to catastrophic failures, forcing customers to find flexible and competent generator manufacturers with the ability to repair GVPI stator windings. This paper presents the most recent successful experiences of Ansaldo Energia Group, one of the power industry’s major suppliers for power plant equipment, who have developed an innovative on-site repair process & methodology for damaged GVPI stator windings. From a single top bar replacement up to the complete stator re-winding passing from the replacement of bottom bars, the techniques, the tools, and the strategies employed by Ansaldo to safely, quickly and reliably repair on-site failed stator winding are presented