A STUDY ON THE EFFECTIVE POWER SYSTEM RESTORATION SCHEMES FOR LARGE-SCALE BLACKOUTS IN SYNCHRONOUS ZONES

摘要

Blackout is a total power failure over a large area, usually caused by the failure of major generating equipment or transmission facilities. Engineering faults, ineffective communication, inability of system operators, operational problems in power system—generation reserve capacity, protection devices, frequency and voltage stabilizers—overloaded transmission lines and transformers, natural disasters, system operation in security limits, instability of supply-demand, and shortages in power investments can constitute these failures. Major blackouts of electric power systems in which many customers are left without power are rare events. However, the effects of blackouts, for instance, can be catastrophic for security of energy supply. rnSecurity of electrical energy supply must be provided by countries for sustainable and successful competition in global perspective and ensuring their citizens’ prosperity. Blackouts can cause not only economic disturbances but also social, security disturbances as well as death. Major factors, sequence of events, and lessons learned from blackouts have been reported in the literature since the first blackout which occurred in 1965, North America. However, these reports are expressly studied on one or more countries in the same area, or more than one blackout in a country (U.S.–Canada Power System Outage Task Force, 2004; Libdahl, 2004; Gomes, 2004a; Yang; 1996). Restoration activities of blackouts which affect multiple countries like 2003 Italy blackout (Berizzi, 2004) in UCTE (Union for the Co-ordination of Transmission of Electricity), 2003 Sweden&Denmark blackout (Larsson, 2004) in NORDEL (Organisation for the Nordic Transmission System Operators), and 2003 Croatia & Bosnia Herzegovina blackout (Dizdarevic, 2004) in UCTE are worked by taking into account the related countries particularly, not whole system that are connected synchronously. rnContinuously, regional interconnected systems, especially in Europe and North America, are in the process of enlargement. Current projects show that, this process also will go on in the future (EU, 2008). Interconnected power grids not only have benefits on security of electricity supply, competition in power markets, and in increasing the quality of electrical energy but also in decreasing the number of major power failures. By the regional integration of the power grids, while power trading, cross-border exchanges, and competition in electricity markets are increasing, not only primary energy sources but also electrical energy dependence will be grown. Related to electricity dependence and rising interconnected power grids, effects and results of major blackouts that affect multiple countries can be enormous. rnBlackouts occurred from past to present and studies on blackouts show that they can not be prevented. However, effects of blackouts can be decreased by lessons learned from the past blackouts. Effective restoration process is very important for decreasing the direct and/or indirect consequences of blackouts. For system restoration to be effective there must be a well thought out restoration plan, training exercises, and verification testing because the exact condition of the system at the time of failure will not be known ahead of time, the plan must be flexible. A great deal of additional information must be assembled and available to the system operator to support flexibility in blackstart operations. By interconnection of regional networks, restoration process of power grids become more important for customers and difficult for systems operator. The main purpose of this paper, different from others in the literature (e.g: Berizzi, 2004; Larsson, 2004; Dizdarevic, 2004; Gomes, 2004b; Roy, 2004; Al Bassam, 2000) restoration process of major blackouts that affect multiple countries in an interconnected grid is worked and suggestions are presented for decreasing the duration and increasing the efficiency of restoration schemes, by taking into account whole synchronous zones.