22 IEEE power & energy magazine march/april 2011

TTHE SECURITY OF ENERGY SUP-ply has become a major concern world-wide, given modern society’s strong dependence on its adequate delivery. Not only does the functioning of in-dustry, transportation, and communi-cation and computer systems depend on a continuous energy supply, but our complete style of living collapses when energy fails. Surges in fuel prices, political confl icts, wars, and natural disasters directly threaten energy sup-ply, and important policy concerns are being implemented as countries look at ways to protect themselves.

Electricity is at the center of atten-tion as today many essential services (water, gas, communications, and the Internet, for example) and infrastruc-tures depend on its continuity for their smooth functioning. On the other hand, electricity power networks have developed to become large and highly complex technical systems, geographi-cally extended, with differing degrees of connectivity, requiring complex op-eration in real time to balance supply and varying demand.

The occurrence of natural disas-ters and their impact on electric power system functioning has been of inter-est to countries worldwide, particu-larly in relation to earthquakes. Several countries such as Chile, China, Haiti, Indonesia, Italy, Japan, Mexico, the Philippines, Turkey, and the United States have experienced severe earth-quakes that resulted in serious damage to their energy supply infrastructure

and at times to their economic devel-opment, in addition to the loss of lives and property. But not only earthquakes and related tsunamis menace our elec-tric infrastructure; havoc can also be caused by severe weather condition such as typhoons, hurricanes, torna-dos, fl oods and landslides, ice storms, volcanic eruptions, and even wildfi res.

In response to this, studies and research in energy security and natu-ral disasters have been conducted around the world. Research cen-ters have been created; for example, the portal h t tp : / /www.cbsnews.com/digitaldan/disaster/ disasters.shtml lists many important links on the subject in the United States. Similar insti-tutions are also in Asia, as listed in http://www.adrc.asia/link/ index.html. Specifi c studies focusing on the impact on electricity supply systems may be found in some of these centers, but there is little published in IEEE periodicals on the matter, al-though conference publications have provided some information.

The complexity of power system networks makes the task of maintain-ing a highly reliable operation a dif-fi cult one, even in normal conditions. Facing short unexpected interrup-tions has been a challenge for mod-ern power system design and control, and much effort is placed on keeping

the system in secure states rather than alert ones. Nevertheless, these efforts occasionally fail, and major blackouts have occurred even as a consequence of isolated faults. Thus, it would be impossible to keep normal intercon-nected power system operation when major natural disasters occur.

Instead, the challenge is to curtail the impact of disasters on the power system and to carry out recovery actions so as to minimize social disrup-tion. Thus, efforts center on power system resil-ience, with resilience defi ned as the ability of a power system to with-stand a major disruption with limited degradation and to recover within a narrow time frame with constricted costs. The goals of resilience en-gineering are a reduced likelihood of damage to critical power systems

and components, limited consequenc-es of failures on society, and reduced time to supply recovery. There is no doubt that power system perfor-mance will be diminished when a major disaster strikes, but adequate countermeasures and response plans can help the system to return to its original functionality. Resilience not only depends on equipment, build-ing codes, and technology but more so on the organization and standard-ized emergency preparedness of well-structured electricity companies.

natural disasterstheir impact on electricity supply

Hugh Rudnick

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Date of publication: 23 February 2011

Natural disasters and their impact on electric power system functioning has been of interest to countries worldwide.

24 IEEE power & energy magazine march/april 2011

Often after a major disaster oc-curs, a proposal to take anticipatory strategies and invest more on security and n–2 or n–3 planning criteria is of-fered. However, this can waste signif-icant investment against threats that may rarely or never occur, whereas re-silience strategies can provide better

protection with lower cost against uncertain events. That does not divert manufacturers and standards develop-ment organizations from designing and building power, communications, and computer equipment that can bet-ter cope with the impacts of those di-sasters in electrical networks.

This special issue attempts to look at specifi c disasters worldwide, quanti-fying their affects on the power systems they have impacted. We have asked experts and utility engineers to share the challenges faced and the lessons learned in different events, and this has resulted in fi ve diverse articles of broadly different disasters.

In our fi rst article, Qiang Xie and Ruiyuan Zhu review how Chinese power systems have coped with three types of natural disasters that have tak-en place in recent years: severe wind storms, ice and freezing rain, and earth-quakes. The interruption of electric ser-vice caused by these natural disasters led to devastating economic losses in rapidly developing China. The lessons learned from these disasters and their consequences are described, as well as actions taken to reduce their impact in the future.

Hugh Rudnick, Sebastian Mocarquer, Eduardo Andrade, Esteban Vuchetich, and Pedro Miquel author the second article and provide a comprehensive report of the February 2010 earth-quake, and related tsunami, that struck the central part of Chile. The authors assess how the earthquake impacted generation, transmission, distribution, and system operation and share chal-lenges faced by electric companies, and their responses.

In the following presentation, An-shel Schiff, who has traveled world-wide to learn effects of earthquakes and draw lessons from them, reports on the 1994 Northridge earthquake. This event occurred in a densely populated area northwest of down-town Los Angeles, California. Based on his experience, he elaborates on how the Northridge earthquake and more recent ones in Chile and Mexi-co have influenced equipment design and testing, substation design, and utility practices.

Then Nicholas Abi-Samra and Wayne Henry report on the impact of fl oods on substations and how to protect against and recover from them and de-scribe how a major U.S. utility handled fl oods in the midwestern United States.

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26 IEEE power & energy magazine march/april 2011

The last article of this issue theme deals with the menaces of terrorism on infrastructure that, together with cyberat-tacks, is a growing world-wide concern. These potential man-made di-sasters often focus on the energy supply, a strong tool to better shock soci-ety and its foundations. Colombia has been a country historically hit by terrorism over the past two decades, and the transmission network has been a frequent ter-rorist objective. Pablo H. Corredor and María E. Ruiz describe attacks on the electrical infrastructure, resultant

power failures, restora-tion procedures after a blackout, development of constrained transmission, cost impact and business recovery costs, and les-sons learned from these emergency situations.

Finally, for the “In My View” column, we asked Eric Fujisaki and Jean-Bernard Dastous, chairs of two related IEEE committees (IEEE 6 9 3 – R e c o m m e n d e d Practice for Seismic Design of Substations and IEEE 1527–Recom-

mended Practice for the Design of Flexible Buswork) to offer arguments on why they believe a much-needed

and benefi cial approach to prepare for natural disasters is the development of international standards.

Clearly, there is no single answer to protect our electricity infrastructure from major natural or man-made di-sasters. Given past events and learning from them, we must learn how to make our systems more resilient and robust in the face of future uncertain and criti-cal threats, while developing new tech-nologies and management features. As Fujisaki and Dastous say, “a reliable electric power supply following disas-ters is too important to be left to the same old approaches of the past.” This issue will become more relevant in the future, as uncertainty increases, and with the possibility of global warm-ing causing even more challenging weather- created disasters. p&e

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