Characteristics of the design, assembly, and experience in operating the generator-motors of the Zagorsk pumped-storage station

Abstract

1. The least reliable link of the generator-motor is the exciting system: both the STSA exciting system itself and the equipment composing it (rectifier transformer and conductor). Here it is necessary to take into account that the rather considerable amount of work on developing the design and exciting system was done by the plant with the participation of specialists of the PSS at the stage of adjustment tests. 2. The need to take into account the conditions of direct asynchronous starting led to forced complication of the design of the generator-motor and, as a consequence, to a general decrease of its reliability. 3. Taking into account that recurring failure related to shorting of the stator winding bars of the generator-motor on the magnetic shunt occurred most intensely on the No. 2 generator-motor being operated with consideration of a large set of tests, including directly asynchronous starts, we can expect an increase of the flow of analogous failures. The use of direct asynchronous starts will intensity this process. 4. During all years of operation of the station a direct asynchronous start was used routinely only once, when the second thyristor starter was still not assembled, i.e., the practical significance of this starting method in a routine respect is negligibly small. Therefore the need and advisability of rejecting this method of starting the units at the Zagorsk PSS with subsequent removal of the magnetic shunts from the stator slots becomes urgent. 5. A check of the compaction of the active steel of the stators of the generator-motors showed a tendency toward a decrease of the compaction pressure with the course of time. Since the long-term dynamics of the change in this pressure for cores with 0.35-mm-thick active steel sheets is unknown, it is advisable to continue periodic checking until stabilization of this parameter.