Dependence of complex indicators of hydroturbine reliability on operating conditions and specific metal content of equipment

Abstract

Operating experience with hydraulic units at active hydroelectric plants is an experiment with the actual operating conditions of equipment, which cannot be performed under laboratory conditions. The value of this experience consists in the fact that it is a unique source of information on the complex reliability indicators of hydraulic machinery. Statistical analysis of retrospective data makes it possible to trace the dynamics of the variation in power-equipment reliability during operation, to ascertain the effect of individual turbine parameters and mode conditions on the reliability indicators and, in turn, to develop measures for improving the reliability of a similar type of hydraulic machinery at newly designed hydroelectric plants.Complex criteria of power-equipment reliability can be obtained on various principles. For a power unit at a nuclear plant, for example, the supply factor of the scheduled generation of electric power II is proposed as a generalizing reliability indicatorwhere AE is the incomplete release of electric power due to failure of an electric unit, and E is the scheduled generation of electric power in accordance with the prescribed regime.A reliability indicator on the basis of the supply of scheduled power can be constructed in a similar manner. Estimates of the reliability of power equipment in accordance with the stability of the operating performance curves of the units are also proposed --for a hydraulic unit, for example, on the basis of the reduction in efficiency for a certain value due to damages sustained by the section between inlet and outlet.Reliability indicators based on the time of the unit's availability to take up the load and the downtime of the power equipment has come into the most widespread use in international and domestic practice. In this case, the following are initial data for calculation of the complex reliability indicators of a hydraulic unit: the operating time tg e in the generator mode; the operating time t s in the synchronous-compensator (SC) mode; the time tre held in reserve; the total downtime for repair ~tr; the scheduled downtime for repair tr. s. Time dependences are also used in calculating complex reliability indicators and other forms of power equipment: steam turbines, gas-turbine units, etc. By themselves, however, the expressions for calculating the reliability indicators of power machinery and methods of plant-data reduction are equal.The reliability of power machinery is most frequently estimated by the operational-availability factor in accordance with the equation [2,3,[12][13][14]