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Impacts of Earthquakes on Electrical Grid Resilience

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Impacts of Earthquakes on Electrical Grid Resilience IEEE/IAS 57TH INDUSTRIAL & COMMERCIAL POWER SYSTEMS TECHNICAL CONFERENCE, APRIL 2021 1 Impacts of Earthquakes on Electrical Grid Resilience Adam Mate 1 Member, IEEE and Travis Hagan 2 Student Member, IEEE and Eduardo Cotilla-Sanchez 2 Senior Member, IEEE and Ted K. A. Brekken 2 Senior Member, IEEE and Annette Von Jouanne 3 Senior Member, IEEE Abstract—One of the most complex and devastating disaster This paper presents some of the key findings of the OTC scenarios that the U.S. Pacific Northwest region and the state of funded research. It aims to systematize power system related Oregon faces is a large magnitude Cascadia Subduction Zone experiences of historical catastrophic earthquakes in order to earthquake event. The region’s electrical grid lacks in resilience against the destruction of a megathrust earthquake, a powerful gain knowledge that can help the PNW to best prepare for tsunami, hundreds of aftershocks and increased volcanic activity, a future CSZ event. The key contribution is a comprehensive all of which are highly probable components of this hazard. collection of proven practices and innovative ideas from other This research seeks to catalyze further understanding and im- regions and nations of the world, on how to improve power provement of resilience. By systematizing power system related system design, construction and operation, which can help to experiences of historical earthquakes, and collecting practical and innovative ideas from other regions on how to enhance network transform Oregon’s and the PNW’s electrical grid into a more design, construction, and operation, important steps are being resilient, earthquake and tsunami resistant power system. taken toward a more resilient, earthquake-resistant grid. This The remainder of this paper is organized as follows. Sec- paper presents relevant findings in an effort to be an overview tion II. gives a comprehensive review on the topic’s back- and a useful guideline for those who are also working towards ground: information about the CSZ and its future, current greater electrical grid resilience. resilience in Oregon and efforts to increase it, and a brief Index Terms—Disaster Preparedness, Earthquakes, Resilience, introduction of historical earthquakes that can serve as exem- Power System Planning, Network Operation. plar cases to provide valuable input. Sections III., IV., and V. present findings related to the generation, transmission I. INTRODUCTION and distribution levels of the electrical grid, respectively. Since the 1980s, when researchers recognized the Cascadia Section VI summarizes the research and concludes with future Subduction Zone (abbr. CSZ) as an active fault, the scientific steps and foreseeable difficulties. community has been aware of the major geological hazard that the state of Oregon and the U.S. Pacific Northwest region II. BACKGROUND (abbr. PNW) faces: the possibility of a tremendous earthquake and tsunami caused by this fault, which can strike at any A. Next Cascadia Earthquake moment and can cause enormous destruction thorough the The CSZ is an approx. 600 miles long offshore fault, which region [1]. lies in the coastal region of the PNW, stretching from Cape The Oregon Talent Council (abbr. OTC), in their Oregon Mendocino in northern California – through the states of Talent Plan [2], identified a critical need for more and better Oregon and Washington – to the Brooks Peninsula in southern prepared electrical power systems engineers to serve Oregon’s British Columbia [1], [3]–[5]. The fault is part of a great arc energy technologies and utility industry. There is an urgent of subduction zones that surrounds the Pacific Ocean, creating need for agile engineers with expertise combining technical a formation called the “Ring of Fire,” and is a geologic mirror education, applied skills, and work experience focused in image of the subduction zone lying east of Japan [1]. disaster preparedness and system resilience. Consequently, In the CSZ, three denser oceanic tectonic plates (namely arXiv:2101.07928v1 [eess.SY] 20 Jan 2021 OTC decided to fund the Pacific Northwest Electrical System the Explorer, Juan de Fuca, and Gorda plates) are sliding from Resiliency and Disaster Preparedness Training Project to west to east and subducting beneath the less dense continental address the existing talent gap; to conduct novel research on plate (North American plate) that moves in a general southwest electrical system resilience, to increase resilience awareness, direction, overriding the oceanic plates. Fig. 1 illustrates the and to train Oregon electrical engineers for disaster prepared- location of the subduction zone and these plates. ness with particular attention to a CSZ event. The movement of these plates is neither constant nor smooth: the plates stick, building stress until the fault suddenly 1 The author is with the Advanced Network Science Initiative at Los Alamos National Laboratory (LANL ANSI), Los Alamos, NM 87544 USA. breaks and releases the accumulated energy in the form of an Email:[email protected]. earthquake(s) [3]. Thereafter, the plates start moving again, 2 The authors are with the School of Electrical Engineering and Computer and continue to move, until getting stuck again. Science, Oregon State University, Corvallis, OR 97331 USA. Email:fhagantr, ecs, [email protected]. There is no doubt that another subduction earthquake will 3 The author is with the Energy Systems Department of Electrical strike the PNW in the future. In the last decade, research has and Computer Engineering, Baylor University, Waco, TX 76706 USA. confirmed that the CSZ has a long history of great earthquakes. Email:fannette [email protected]. Color versions of one or more of the figures in this paper are available The most recent happened on January 26, 1700, creating a online at https://ieeexplore.ieee.org. magnitude 9.0 earthquake followed within minutes by a large IEEE/IAS 57TH INDUSTRIAL & COMMERCIAL POWER SYSTEMS TECHNICAL CONFERENCE, APRIL 2021 2 for the next fifty years. Up until today, two CSZ earthquake scenario documents have been created, [3] and [5] (with multiple versions), with the goal to provide information for the public on the hazards the PNW faces. These three studies [1], [3], [5] identified the following key findings on the current state of resilience of Oregon’s electrical grid: • Electrical facilities and network components – includ- ing power plants, substations, transmission lines – are seismically vulnerable to damage and have significant risk due to ground shaking and ground failure, especially landslides, soil liquefaction, lateral spreading and coastal subsidence hazards. • Most of Oregon’s critical and non-critical energy infras- tructure has been constructed with seismic design defi- ciencies, and not initially built to with-stand earthquakes. Substantial improvements, investments, and a uniform set Fig. 1. Schematic view of the tectonic plates in the CSZ area [5], [6]. of design and construction codes are needed to minimize extensive direct earthquake damage, indirect losses, and tsunami. Energy for the next earthquake is currently building possible ripple effects. up along the fault, and has been since the last earthquake [1], • A CSZ event will cause the failure of numerous power [3], [5]. The time interval between previous CSZ events varied system components, and over half of the region’s electri- from a few decades to many centuries, but most intervals were cal grid may suffer medium to high damage on all grid- shorter than the time elapsed since the last event in 1700 [1]. levels. Outages and blackouts may occur not only within The calculated odds that the next earthquake will occur in 100 miles of the coastline, but even in areas that were the next 50 years range from 7-15% for a “great” earthquake not directly affected by the earthquake. The destruction affecting the entire PNW to about 37% for a “very large” on the coastal areas may be severe enough as to render the earthquake affecting southern Oregon and northern California equipment and structures irreparable. In the I-5 corridor, [1], [3]–[5]. considerable damage on generation and distribution levels Geologists assembled a ten-thousand-year record of past may result in the loss of over half of the system’s capacity. events, by studying sediments in coastal marshes and on the • Oregon’s liquid fuel supply is extremely vulnerable. Be- ocean floor. This shows that half of the past earthquakes sides the high dependency on Washington State – more have been “very large” (estimated magnitude of 8.3 to 8.6) than 90% of Oregon’s refined petroleum products come and centered on the southern Oregon coast, while the other from the Puget Sound area, which is also vulnerable to half have been “great” (estimated magnitude 8.7 to 9.3) and a CSZ earthquake – the storage facilities along Oregon’s extended along the full length of the fault [1]. Although it Willamette River lie on liquefiable riverside soils. This is possible that the next CSZ earthquake(s) will be a partial significantly affects most sectors of the economy critical rupture of the fault, section by section, in a series of large to emergency response and economic recovery. events over a period of years, it is strongly anticipated by • Estimated restoration time of electrical grid after a CSZ many scientists that it will be similar to the last event in 1700, event ranges from 1-3 months (in the Willamette Valley) and will be the result of the entire fault rupturing, causing to 3-6 months (Coastal region), depending on the degree one great earthquake measuring magnitude 9.0, with ground of destruction, available utility personnel, contractors and shaking lasting 4-6 minutes [3], [5]. road conditions. Even though small steps – conducted studies, funded re- search, legislative changes — have been taken in the recent B. Earthquake resilience in Oregon years to start and accelerate the needed change in this issue, After the discovery of the major threat, the rate of change to Oregon’s electrical grid today is still far from resilient to the increase Oregon’s resilience has been slow.
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