Technical and economic aspects of the supply of reactive power in England and Wales

Abstract

The paper discusses some problems of supplying reactive power in the transmission and distribution systems of England and Wales.The overall reactive-power requirements of the inductive loads of consumers and the shunt and series inductances of the system are reviewed and their effect on generator characteristics is examined. Consideration is given to the problems of supplying the demand for reactive power by means of the generators, system capacitance and compensating devices, and a scheme is outlined for the effective control of reactive power and voltage. An example is given relating to the possible conditions when the system load reaches 30 GW, and it is shown that the kVAr/kW ratio at bulk supply points for the optimum loading of the generators postulated is about 0.4 (0.93 lagging power factor) at times of peak load.Estimates are made of the extra cost of providing and operating a power-supply system to transmit reactive power as well as active power. Consideration is given to various forms of tariff adjustment for reactive-power supply, leading to a preference for separate charges for active and reactive power demands.The advantages and disadvantages of generating reactive power at or near the load, by the consumer or by the supply authority, are discussed. It is concluded that present methods of tariff adjustment are generally effective in inducing consumers to limit their demands for reactive power to an extent which would make uneconomic the provision of additional sources of reactive power on distribution systems.