ALLEVIAMI OF VOLTAGE LIMIT MOON IN POWER NETWORKS

Abstract

There is a tendency of power transmission systems of today to - operate closer and closer 'to their physiCal limit. It As not'. _uncommon that the 'limitingfactor for Tower- transformers in the- ,. . . . , . systems ..today is the risk of voltage instability. As a,, consequence, at least some 15 incidents -of voltage collapse occurred world wide during the- 1970's and 1980'S [17]. In the event of an approaching blackout, the disconnection of loads under -controlled conditions and/or blocking of the tap changers on transformers and/or routine power generation of the, generator buses and switchblade reactors, or, capacitors can minimise_ the damage sustained. In :the past, operators maintained reliable performance of the power system :using :their. experience .and on-the-spot assessment, of network conditions. Tbwever, networks are now large, complex , and , highly int erl inked. The- increased number •of possible operating scenarios can lead to. situations where the operator's analytical ability may even fail., The remedy' to such situations is the centralized .control over power resources and more dependence on computers to asSist.-Ihe operator An system monitoring, control -and economic dispatch. Though: understanding of bulk power tranSmission- system- As essential _when, it is heavilytilized, to ensure reliable and -economic service, to customers. As the transmission line become overloaded, the system operators are •faced with, increasingly difficult reactive and voltage control problems..