Allocation of distribution system losses to consumers in deregulated electricity supply industries

Moves towards the deregulation of the electricity supply industry in many parts of the world have led to the introduction of varying degrees of competition in certain sectors of the business. In countries such as the UK, where competition has been extended into the supply side of the business, it has been necessary to distinguish between the costs of energy and the costs of transporting the energy to the consumer. Currently in the UK, nonfranchise customers (whose annual maximum demands exceed 100 kW) may purchase energy from any licensed supplier, paying the local distribution company a `use of system´ charge for transmission of the electricity to the point of use. An important element of these use of system tariffs is a table of loss adjustment factors that reflect the percentage by which purchases of energy at entry points to the system must exceed consumption at the point of use to account for the losses which occur in between. Distribution companies are obliged to calculate loss adjustment factors on an individual basis for major consumers, and this has brought about the need for techniques which allocate losses on a more detailed basis than was necessary prior to deregulation. This paper describes a new approach to the evaluation of loss adjustment factors for distribution systems, which combines the use of graph theory with readily available load flow results, to assign the losses in each line or transformer within the system to the consumers supplied by it