CONTROL STRATEGIES FOR RECOVERING SECURITY MARGINS IN INTERCONNECTED COMPETITIVE POWER SYSTEMS

摘要

This paper deals with some possible improvements inrnmanaging dependability and risk of globallyrninterconnected systems in the new liberalisedrnelectricity markets.rnIn such a new context there is the need to improvernreliability and security of electric power systems,rnguaranteeing adequate margins in normal conditions asrnwell as in transient conditions arising after severerncontingencies.rnThe paper describes a first series of improvementsrnrelated to new developments in on-line DynamicrnSecurity Assessment (DSA) and evidences the possiblernintegration of DSA with Stability Controls.rnFurther improvements are conditioned by thernpossibility of determining emergency control decisionrnrules, fast and effective, based on the establishment ofrnsecurity assessment indices & criteria. The classicalrnsecurity topics (transient stability, voltage collapse andrncascade line tripping) may be covered through a fastrnacquisition of angle measurements at area significantrnnodes and line interconnections buses.rnThe proposed strategies imply shared agreementsrnamong different interconnected countries for facingrntransient system behaviours.rnAs far as control techniques are concerned, thernpossibility to transmit to local controllers, in a very fastrnway, the state of all the needed measurements, nowrnallows actions more intelligent than in the past.rnFurthermore, very fast devices, able to control activernand reactive power through the lines are available. Arnvery promising proposed approach is presented, basedrnon a classical non-linear model of the network and onrnthe technique of compensating the feedbackrndisturbances. Such an environment represents also arnuseful framework for future closed-loop controlrnsystems, capable of exploiting power system devicesrnboth conventional (Phase Shifter) or modern-typern(FACTS), in order to achieve continuous stabilisingrnactions for facing unexpected contingencies.