Provision of reactive power from generating plant

In the UK, the Grid Code requires generating plant to be rated to have a fixed reactive power capability whether it is required or not. This has arisen partly because it is an expedient mechanism to guarantee availability of a significant reactive power capacity, irrespective of which power stations are operating, and because it is acknowledged that producing reactive power from generating plant is normally the cheapest option. However, the cost is not zero; it increases plant capital costs, produces efficiency losses, increases maintenance and repair costs, leads to more rapid ageing of the machine and causes other consequential but significant costs in managing plant risks and regulatory obligations. The implications of providing reactive power from generating plant are explored in this paper.