Economic Benefits of Hydrogenerator Rotor Pole Redesign and Field Winding Refurbishment to Accommodate Future Operational Regimes

Over the last decade, large hydropower plants have shifted their operational regimes from nominal conditions to more diversified load cycles owing to the increasing share of intermittent renewables that have necessitated more flexible hydropower operations. However, increased load variability has made the hydrogenerator efficiency a more important economic metric. This paper proposes a method for redesigning the hydrogenerator rotor pole and refurbishing the field winding to enhance the economic performance. The effectiveness of these changes was evaluated by estimating the levelized cost of non-optimal operation across various operating regimes. We present two alternative rotor redesigns for a 103-MVA hydrogenerator, which indicate significant economic benefits for a diverse set of load cycles. Generally, the net present value of these benefits is found to be four to five times greater than the material costs incurred during the refurbishment phase.