The multi-channel (MC) back-to-back voltage source inverter (VSI)-fed doubly fed induction machine (DFIM) is emerging as a highly interesting topic in large-rated variable speed pumped-storage power plants (PSPP) in view of cost, optimal efficiency, and space requirements. Although the VSI is the fundamental part of the drive controlling the active/reactive power of the plant, redundancy is presently not adopted in practice causing the unit as a whole to shut down upon a failure in the converter and control circuit. This paper evaluates a large-rated (250 MW) DFIM-fed variable-speed unit of a PSPP in terms of its reliability and availability. A Markov model is developed to assess the reliability of the drive based on a number of factors including survivability and annual failure rate (FIT). Further, the Markov model is applied to different PSPPs for comparison of reliability among them.
Risk of penstock fatigue in pumped-storage power plants operating with variable speed in pumping mode
