Optimal operation of variable speed pumped storage hydropower plants participating in secondary regulation reserve markets

Pumped storage hydropower plants can contribute to a better integration of intermittent renewable energy and to balance generation and demand in real time by providing rapid-response generation. In order to invest in a new pumped storage plant, it is necessary to assess carefully the profitability of the project as the recovery of investment costs could be jeopardised by many factors. Apart from participating in the day-ahead market, ancillary services can also play an important role when determining the incomes. The aim of this paper is to make a preliminary comparison of pumped storage plant's market incomes with and without ability to regulate power in pumping mode through variable speed technology. A deterministic mixed-integer programming model is proposed to calculate power bids for the day-ahead and secondary regulation markets. The model considers the hourly day-ahead and secondary reserve market prices as well as usage and prices of secondary regulation-up and down energy requested by the Spanish System Operator.