Metering equipment to allow competition in the supply of electricity

The majority of generating stations are connected to the National Grid (although some are “embedded” in the systems of PESs). Metered values of supplies generated are summated and aggregated as to each generating company. Supplies taken by PES´s are likewise summated and referenced to Grid supply Points (GSPs) from which supplies are taken. The Pool then carries out a reconciliation between generators and suppliers, on a day by day, half-hour by half-hour, basis. An important principle arises in the case of GSPs shared by two PESs. Total supplies to the GSP and supplies to the PES B are metered, the “take” of PES-A then being the difference. This principle-of “difference metering” is also applied to embedded generation, inter-PES supplies and Second Tier customers. Supplies may be offered into the Pool by anybody holding a Generation Licence and having a generation output of over 50 MW. Suppliers to end customers require either a Public Supply licence or a Second Tier Licence. Other physical suppliers into the Pool include the two Scottish Companies, via interconnectors at 132 and 275 kV between Scotland and England; Electricite de France (through an operating Company) via the DC Cross Channel Link; and the Dinorwic and Ffestiniog Pumped Storage plants (operated by a subsidiary of the National Grid Company)