Energy storage methods for two hydro plants

WHEN TWO or more hydroelectric storage plants are located on a river so that storage from upstream reservoirs will be used through downstream plants, certain methods of storage withdrawal will produce more energy as needed by the load than others. As the net head drops due to storage withdrawal at any plant, all natural flow water as well as remaining upstream reservoir storage then must be used at some lower averaged head, until refill is made later during a period of high river flow. Only incremental energy obtainable from storage withdrawal is used here for comparison of various methods and five components of incremental energy (ΔE) are obtained for each method. Three components are positive; plant 1 storage through plant 1, plant 2 storage through plant 2, plant 1 storage through plant 2; two components are negative; plant 1 natural flow through plant 1, and plant 2 natural flow through plant 2. The last two are obtained due to drops in head and from the total natural flow passing during the period of reduced head.