Provision of rotating reserves from wind power in a hydro-dominated power system

This paper investigates how wind power can contribute to the provision of rotating reserves in a hydro-dominated power system with limited transmission capacity to an exogenous power market. We emphasize on the impacts different schemes for providing rotating reserves has on the generation dispatch and rotating reserve (RR) cost. Due to the flexibility provided by hydropower, the system is well suited for facilitating a large share of intermittent energy. We approached this by building a model based on Stochastic Dual Dynamic Programming (SDDP), which efficiently handles multistage stochastic problems. A case study is presented based on the properties from the Nordic power system. Results shows that for wind penetration levels above 20%, some wind power is used for the provision of upwards RR at higher costs than the hydropower could provide, but freeing up more flexibility for the hydropower units and subsequently higher overall gain. The use of wind power to provide downwards RR proved to be very cost efficient, as there is no opportunity cost associated with the use of wind power.