The Dinorwic pumped-storage scheme

The CEGB has a statutory obligation to provide electricity within ±0.5 Hz of the nominal 50.0 Hz frequency and within ±6% of the declared voltage. The objectives are met by operating 137 coal, oil, gas, nuclear and hydro power stations in a highly integrated power system. In such systems, pumped-storage plants can assist in meeting the objectives in a number of ways