The parallel operation of generating plant within a regional electricity company´s distribution network

The Energy Act (1983) established a right for persons or companies to use the public electricity supply systems to transmit energy from one location to another or to third parties. The publishing in October 1988 of the revised Electricity Supply Regulations set out the statutory requirements for those wishing to operate private generating plant. This has led to a considerable increase in generation embedded in distribution networks ranging in size from about 15 kW to 10 MW or more. Connections can be at a voltage level ranging from 1 V through to 33 kV or even 132 kV and typical energy sources used are water, waste heat from chemical processes, combined heat and power units and gas from refuse disposal plant or tips. The author addresses the effect of the growing numbers and sizes of relatively small embedded generators on the operation and performance of distribution networks. The author concentrates on technical issues and not on the regulatory or operational procedures. The issues discussed include voltage regulation, fault currents, islanding, system stability, earthing and protection of the interface between the network and embedded generator