Resilience and the Electric Grid
Argonne National Laboratory is developing methodology to produce a resilience metric for U.S. critical infrastructure that can be used to identify gaps in planning, mitigation, response and recovery measures.
By Julia Phillips, Ph.D., Celia Porod, and Frédéric Petit, Ph.D., ABCP, M.SAME
Lightning strikes to power distribution stations and other natural and man-made events can cause significant damage and service interruptions. Research underway at Argonne National Laboratory seeks to develop tools and metrics for better understanding electrical grid resilience. PHOTO COURTESY SHUTTERSTOCK
The United States faces the ongoing challenge of protecting its national critical infrastructure from significant damage caused by extreme weather events. As natural hazards increase in frequency and intensity, the efforts of owners and operators to enhance the resilience of their systems and assets is more crucial than ever.
The need to understand and enhance the protection and resilience of U.S. critical infrastructure has been a national focus since the President’s Commission on Critical Infrastructure Protection was established in 1996. Approximately one year after the events of Sept. 11, 2001, the Department of Homeland Security was created with a mission to formally identify the nation’s critical infrastructure and examine infrastructure vulnerabilities, whether man-made or natural. The release in recent years of Presidential Policy Directive-8 on National Preparedness and Presidential Policy Directive-21 on Critical Infrastructure Security and Resilience further emphasized the importance of understanding the resilience of citizens, communities and critical infrastructure.
DELIVERY AND RELIABILITY
Resilience of the electric grid in particular has continued to gain attention since the Energy Independence and Security Act of 2007. In 2009, the Department of Energy (DOE) through the American Recovery and Reinvestment Act was allocated $4.5 billion for investment in electricity delivery and energy reliability in support of grid modernization. To help facilitate this work, in June 2011, the Office of the President, National Science and Technology Council, released a policy framework focused on making cost-effective investments, encouraging innovation, educating consumers to make smart decisions, and securing the grid from attacks.
Recent attention on the potential impacts of climate change, including The President’s Climate Action Plan, released in June 2013, underscore the importance of modernizing the grid. Grid modernization not only emphasizes the integration of clean fuel for energy production, it highlights the need for increased reliability of electric power delivery and cost savings for consumers.
The electric grid provides energy to all 16 critical infrastructure sectors and is strongly interconnected with other lifeline utilities such as water, natural gas, and telecommunications.
Enhancing resilience will minimize the cascading and escalating failures generated by the interruption of electric power components that could propagate throughout a community or region, such as happened during Superstorm Sandy.
In the context of critical infrastructure, resilience is defined as the ability of a facility or asset to anticipate, resist, absorb, respond to, adapt to, and recover from a disturbance. DOE’s Office of Electricity Delivery & Energy Reliability recently initiated a program to better understand the resilience of electric distribution systems across the country. Argonne National Laboratory, in support of this initiative, is developing an assessment methodology and survey tool to collect information from electric utility operators that will help assess the resilience of the electric distribution infrastructure to extreme weather events. For this research, the six key components of resilience are aggregated into the four major domains as shown in Table 1: preparedness, mitigation, response, and recovery.
A comprehensive understanding of the grid and of the components required to deliver electric power is necessary to characterize the resilience of distribution systems. In alignment with the four major resilience domains, collected information will be used to assess a distribution system’s ability to prepare for, mitigate, respond to and recover from a disturbance.
UNDERSTANDING THE SYSTEM
Resilience is a function of both physical reliability factors and intangible resilience indicators. Commonly considered reliability factors include system voltage, feeder length, exposure to natural elements (overhead or underground conductor routing), sectionalizing capability, redundancy, dependencies and interdependencies, conductor type/age, and the number of customers on each feeder. Intangible resilience indicators that complement reliability factors include business continuity, emergency management, procurement management and preventive maintenance planning; training and exercising of plans focused on responding to disruptions; relationships with local emergency responders; and the ability of facilities that are dependent on the electricity distribution system to perform their core mission.
Also, the variability of electric distribution system characteristics related to their geography, the number of customers served, and the type of extreme weather events that are encountered must be considered in an overall assessment of resilience.
CAPTURING CRITICAL INFORMATION
The conceptual components of resilience are captured using data collection questions covering the four major domains of resilience. Table 2 provides a framework for data collection under the resilience domains.
Within each of the broad categories outlined in Table 2, the new survey tool captures information on utility characteristics (such as control and dispatch centers, lines and substations); the potential consequences generated by disruptions; extreme weather exposure; existing agreements and information-sharing processes; resilience planning; response capabilities; and the main dependencies supporting system operations (electric power, communications, fuels, chemicals and transportation).
A decision-analytic technique, Value-Focused Thinking, then will be used to determine the contribution of each component captured in the survey tool to the overall distribution system resilience. Through a formal elicitation process, subject matter experts will place relative importance values on all of the components contributing to resilience. These judgments will be used to calculate a system resilience performance metric similar to the Resilience Measurement Index, which is a tool that characterizes the resilience of critical infrastructure at the facility level. The resulting resilience indicator for electric power distribution systems will aid critical decision-making by identifying gaps in resilience measures. Once the methodology is completely established and the survey tool fully created, it will be made available to all electric distribution owners and operators to use on a voluntary basis.
The organizational framework outlined in Table 2 will act as a guide to the private entity owners and operators for identifying the applicable components of their system-specific resilience. By defining the characteristics and components that contribute to resilience, stakeholders will be able to see possible solutions for system enhancement.
POWERING THE FUTURE
As climate change gains growing recognition as a cascading problem, and as infrastructure resilience emerges to the forefront of public discussions, the need to understand impacts and reaction to key national lifeline sectors is critical.
DOE is actively pursuing greater understanding of the resilience of the national electric grid and identifying opportunities for government support in enhancing resilience. The electric distribution resilience assessment methodology and survey tool is one example of that vital support.
With the help of information on best practices and needs from the private sector, improvements can be made today that will ensure the operation and resilience of the grid for tomorrow.
Argonne National Laboratory's work was, in part, supported by the U.S. Department of Energy, Office of Science, under DOE contract number DE-AC02-06CH1