When the Lights Go Out
Getting Power Systems Running Again
“Where were you when the lights went out?” This question has become more and more common in communities suffering from major storms and other power outages resulting from design failures, equipment misoperations, and errors by both operators and planners. Engineers are doing their best to harden the grid and promote high levels of reliability required for meeting the demands of the digital age. More fundamentally, electricity is the lifeblood of any society. As a best case, the widespread loss of electricity disrupts the economy and disturbs daily routines. As a worst case that has become increasingly common, the loss of electricity can result in the loss of lives and exacerbate the consequences of natural disasters.
Engineers and the regulatory community apply lessons learned from major power system events. The great U.S. Northeast blackout of 1965 resulted in the formation of reliability councils and power pools and improved the coordination of bulk power system operations and planning across wider areas. The blackout of 14 August 2003 gave rise to mandatory reliability standards intended to prevent widespread outages of power system infrastructure. More recently, the massive destruction of electric power infrastructures from storms such as Hurricane Katrina and Superstorm Sandy have triggered the hardening of power system facilities against natural phenomena.
“Do you have power yet?” The means of achieving rapid restoration of electric service is a critically important requirement of power systems that can only be accomplished with both the necessary infrastructure and deployment of qualified personnel. Restoration is realized with reliable sources of black start power and a transmission and distribution network that provides flexible paths for restoring service as quickly as possible. Personnel must be well trained before they can develop and execute successful restoration plans. Operational communication media and the clear exchange of information among people and equipment are necessary ingredients for the successful implementation of any restoration plan. Technological advances facilitate system restoration by providing new sources of power, improving observability and controllability of the network, and assisting system operators with “expert system” advice on real-time system procedures.
Sophisticated technologies are being developed and applied to the power system, including flexible alternating current transmission systems, phasor measurement units, and variable energy resources. In addition, distributed resources hold the promise of improving reliability through microgrids. All of these and other technological changes provide tremendous opportunities for improving the reliability of power supply to loads, and they hold the promise for rapidly restoring the system after unavoidable outages of electric power service. The implementation of new technologies, however, also poses major challenges that must be addressed. Gone are the days of command and control of the power system and a simpler time when operators could easily predict the system response using their innate feel for the system. Operators must now deal with the application of many new sources of power; variable generation and unknown load characteristics; and the coordination of disparate entities owning generation resources, transmission systems, distribution facilities, distributed generators, and loads. Distributed control of the network and other technological advances, however, are improving the human-machine interface and the reliable operation and planning of the power system.
Standards must keep pace with technological developments. For example, IEEE Standards Coordinating Committee 21 (SCC21) is actively working on amending IEEE 1547-2003 to address voltage regulation (VR), voltage ride-through (VRT), and frequency ride-through (FRT) that better coordinate with transmission system requirements. As of this writing, the amendments of draft 1 of IEEE 1547 will not mandate VR/VRT/FRT, but the draft standard will be permissive of these capabilities “as mutually agreed to by the area electric power system and distributed resource operators.” In my opinion, further consideration should be given to a VR/VRT/FRT mandate because the anticipated large-scale integration of distributed resources could pose a serious challenge to both the reliable operation and the rapid restoration of the power system.
IEEE is addressing necessary issues to successfully integrate new technologies, as shown by the wide range of publications and professional activities. This issue of IEEE Power & Energy Magazine focuses on power system restoration, so acknowledgement of the extraordinary work done by the IEEE Power & Energy Society Restoration Dynamics Task Force (RD TF) is in order. The RD TF, chaired by Nelson Martins, was formed in 2006 to address potential restoration dynamic problems. The RD TF was a subgroup of the Power System Stability Controls Subcommittee, chaired by Leo Lima of the Power System Dynamic Performance Committee, which was chaired by Prof. Thierry Van Cutsem. And no discussion of power system restoration is possible without acknowledging the many contributions by Mike Adibi and all that the industry has learned from him as the long-term expert and mentor on restoration issues. I fully encourage IEEE members to participate in further activities that will continue to address power system restoration issues.
In This Issue
The articles in this issue discuss key aspects of system restoration and summarize some of the great work being done within the electric power industry. The issue reviews some of the lessons learned from operating experience and the improvements made to restoration operating procedures, the physical aspects for planning and operating the restoration of the system, and new technologies that improve reliable operation of the system and more rapidly restore service during the inevitable outages.
It has been more than ten years since much of the U.S. eastern interconnection was blacked out and then successfully restored by dedicated and highly competent personnel. A retrospective of both the system restoration process used and a summary of lessons learned is provided in the article “No Light in August: Power System Restoration Following the 2003 North American Blackout,” by Eric H. Allen, Robert B. Stuart, and Thomas E. Wiedman. The article also discusses the regulatory recommendations that resulted from the blackout and some of the standards that must be followed for system restoration.
Restoration of the system poses technical challenges that must be addressed. “Down, but Not Out: A Brief Overview of Restoration Issues,” by James Feltes and Carlos Grande-Moran, discusses the general philosophy, plans and procedures, studies and analyses, and several other aspects of the blackstart process. The article describes system operations during restoration and the studies that should be part of a restoration planning process that minimizes the disruption of service to load and reduces the risk of damage to equipment. The article should be helpful to utility staff who develop restoration plans, perform simulation testing, and conduct drills.
“The New Black Start: System Restoration with Help from Voltage-Sourced Converters,” by Michael Bahrman and Per-Erik Bjorklund, describes the operating experience of actual facilities. Voltage sourced converters (VSCs) have the ability to provide dynamic voltage support, control network power flows, and connect asynchronous grids or intact islands within the larger power system. FERC Order 1000 removes arrangements that protect the right of first refusal for incumbent transmission providers and would likely increase the future applications of VSCs.
“The Healing Touch: Tools and Challenges for Smart Grid Restoration,” by Shanshan Liu, Yunhe Hou, Chen-Ching Liu, and Robin Podmore, provides a background on blackouts and their impacts and the use of smart restoration technologies. These include physical improvements to the power system that will reduce restoration time while maintaining system integrity, such as technologies that improve wide-area situational awareness and decision support tools for power system operators. The application of system recovery technologies can help operators restore the system under the wide variety of unpredictable power system operating conditions that may be further complicated by the high penetration of variable energy resources and demand response.
The restoration process for distribution systems has continued to evolve and improve as summarized in “A Changing Map: Four Decades of Service Restoration at Alabama Power” by G. Larry Clark. Situational awareness and the efficient and reliable restoration of the distribution system have improved through the application of distribution automation, system control and data acquisition, and desktop computing. The article also discusses improvements in the human-machine interface achieved in the control room.
Microgrids have the ability to provide continuous electric service to loads following outages of the distribution system. They can also assist with the restoration of the power system by energizing portions of the distribution system, which ultimately are resynchronized with the transmission system. “Only Connect: Microgrids for Distribution System Restoration” by Liang Che, Mohammad Khodayar, and Mohammad Shahidehpour discusses the need for microgrids and how they can improve the reliability of service to loads.
I’m very grateful to ISO New England, where I work with an extraordinarily capable staff on exceptionally interesting projects. The ISO has been supportive of IEEE, my favorite volunteer organization, which has provided me with outstanding professional development and a network of good friends across the globe. Thank you to the authors of this issue who have worked so hard and have readily shared their remarkable expertise. A particular thank you to Mel Olken, editor-in-chief of the magazine and a friend and mentor of over 35 years, who provided me with the opportunity of serving as guest editor of this issue.