Global Blackouts - Lessons Learned

摘要

The growth and extension of AC systems and consequently the introduction of higher voltage levels have been driven by a fast growth of power demand over decades. Power systems have been extended by applying interconnections to the neighboring systems to achieve technical and economical advantages. Regional systems have been built-up towards national grids and later to interconnected systems with the neighboring countries. Large systems came into existence, covering parts of or even whole continents, to gain the well known advantages, e.g. an ability to use larger and more economical power plants, reduction of reserve capacity in the systems, utilization of the most efficient energy resources, and to achieve an increase in system reliability. Global studies show that power consumption in the world follows closely the increase of population. In the next 20 years, power consumption in developing and emerging countries is expected to increase for 220%, in industrialized countries, however, only for 37% (IEA; UN; Siemens PG CS4 - 08/2002). In future, in the course of deregulation and privatization, the loading of existing power systems will strongly increase, leading to bottlenecks and reliability problems. System enhancements will be essential, to balance the load flow and in total to get more power out of the existing grid. Large blackouts in America and Europe confirmed clearly, that the favorable close electrical coupling of the neighboring systems might also include the risk of uncontrollable cascading effects in large and heavily loaded interconnected systems. An overview of the sequence of events of the US/Canada and European blackouts is given and countermeasures for blackout prevention -"Lessons learned" - are discussed. Avoidance of loop flows, prevention of voltage collapse, elimination of stability problems in large power systems and the implementation of "firewalls" are presented. The benefits of HVDC (High Voltage DC Transmission) and FACTS (Flexible AC Transmission Systems) for system enhancement are explained.