Variable speed operation of reversible pump-turbines at Kadamparai pumped storage plant – A case study

• We examine feasibility of variable speed operation for a pumped storage plant.
• We analyzed existing annual operation with variable speed machines.
• Results show variable speed machines are beneficial than fixed speed machines.

While carrying out renovation and modernization, introducing new technologies for improving the power station performance is a universal practice. In this context a study has been conducted for the 26 year-old Kadamparai pumped storage plant (4 × 100 MW) located in the state of Tamil Nadu, India, with the objective of adopting variable speed technology while undertaking renovation & modernization in not-so distant future. Present peak power demand and the expected capacity addition through thermal, nuclear, solar, wind energy power plants to the state grid needs a review on the existing operation of Kadamparai pumped storage plant to meet out the peak and energy shortage of the state. The existing conventional synchronous machines of this plant can be operated as variable speed machines by adopting static frequency converters (SFC) between stator and grid supply or replacement of existing synchronous machines with variable speed induction generators to utilize the grid load variation effectively. Annual operation of Kadamparai pumped storage scheme with variable speed machines has been analyzed in the existing hydraulic conditions. Additional benefits that is likely to accrue as compared to conventional synchronous speed operation has been calculated. Results show that the variable speed technology has considerably increased the plant performance.