High-Impact Low-Frequency Research Articles

Availability of state-level climate change projection resources for use in site-level risk assessment

In recent years, incorporating climate change considerations has become an important focus of organizations’ resilience planning and risk assessment efforts, including United States federal agencies. This has led to an increasing demand for higher-resolution and higher-quality climate projection information that is easy to understand for non-expert users. In particular, there is a demand for information about how climate change may affect high-impact, low-frequency (HILF) hazards that are central to risk assessments focused on infrastructure. While national-level resources like the National Climate Assessment provide information on climate impacts for different sectors and regions in the United States, downscaled information with location-specific context is often required for site-level resilience planning. As higher-resolution and higher-quality climate resources continue to be developed at the state level, it is imperative to understand ongoing and planned efforts, as well as key drivers for developing these state-level resources. Based primarily on stakeholder input from climate experts from 31 states, we identify key state-level climate resources, as well as drivers accelerating the development of these resources. We assess the availability of climate change resources, specifically those with information about HILF events that have been developed at the state level and can support users in conducting site-level resilience planning. We identify three key drivers or predictors for the development of climate change resources at the state level: (1) existence of state laws, mandates, Executive Orders, and other state policies, (2) existence of university partnerships; and (3) the makeup of the stakeholder groups (in terms of dominant discipline/expertise) participating in the effort. The diverse state strategies and resources surveyed in this study could support the incorporation of higher-resolution climate information into site-level planning.

Data-Driven Resilient Load Forecasting Model for Smart Metered Distribution System

The change in the electricity demand pattern globally due to sudden extreme weather conditions or situations like COVID 19 pandemic has brought unanticipated challenges for the electric utilities and operators around the world. This work primarily deals with the issue of load forecasting during such type of high impact low frequency (HILF) events. In this paper, we propose a novel resilient short-term load forecasting model capable of producing good forecasting performance for normal as well as critical situations during the COVID 19 pandemic and will also be useful for load forecasting for other HILF situations like natural calamity effect on load demand of the power system. The proposed method uses a feed-forward neural network (FFNN) with an added training feature named resiliency factor to forecast load in both regular and special scenarios. The resiliency factor for any type of node in the distribution system is decided by the power utility using the historical data and declared in advance. The proposed model is tested using the smart metered data available from a real-life distribution grid of an academic cum residential campus. The model is giving satisfactory results for both normal as well as COVID scenario for the said network.

Impact of situational awareness attributes for resilience assessment of active distribution networks using hybrid dynamic Bayesian multi criteria decision-making approach

The planning and operation of distribution systems have significantly changed due to the extensive osmosis of ICT (information and communication technologies) into power systems. Load growth, together with increased power quality expectations by the customers, has transformed the conventional distribution network to active distribution network (ADN), with penetration of distributed energy resources (DERs). This has imposed the necessity to analyze resilient performance of ADN subjected to the boon of ICT for enhanced situational awareness (SA). This paper focuses on a detailed multi-level hierarchy framework using linguistic scale based multi-criteria decision-making (MCDM) approach for SA oriented resilience level estimation of ADN, considering different high impact low frequency (HILF) events. The rapidly changing environmental conditions and ambiguity in interaction of network parameters lead to non-deterministic resilience (NDR), thus, affecting the operational resilience of ADN on a daily basis. To analyze the uncertain ADN availability due to NDR, hybrid MCDM-dynamic Bayesian network (DBN) approach is used. For better decision-making, the operational performance of ADN, to withstand critical loads due to NDR is analyzed in terms of load not served (LNS) index. The proposed framework is tested on IEEE 33-bus distribution network.

Hybrid data-driven resilience assessment and enhancement of distribution system for cyclone susceptible zones

The sprawl of distribution system towards the need of smart grid, demands better sustenance and adaptation strategies to deal with high-impact low-frequency (HILF) events. One of the predominant causes of HILF events are natural calamities. Therefore, the resilience assessment of the distribution system is inevitable. The contributions majorly focuses on hybrid data driven approach using micro-phasor measurement unit (μ-PMU), for dynamic voltage, current phasors monitoring, and unmanned aerial vehicle (UAV) confirms structural vulnerability of nodes within network. Mesh grid approach, which analyses cyclone trajectory affecting the network, supplemented identification of most vulnerable part within network. However, priorities of vulnerable nodes are corroborated using complex network (CN) theory. This hybrid data driven approach and spatial parameters are used to estimate appropriate mitigation strategies against HILF scenarios. Hence, resilience analysis based on location parameters and dynamic network conditions are further analyzed based on degree of correlation of location dependent resilience with latitude, elevation, and probable water level. Based on susceptible vulnerable nodes, identification of optimum alleviation schemes is adopted and justified using resilience trapezoid. To validate efficacy of the proposed approach, the analysis is tested on IEEE 33-bus distribution network subjected to 5 cyclone prone geographical coordinates for 20 years cyclone data.

A Stochastic-Robust Approach for Resilient Microgrid Investment Planning Under Static and Transient Islanding Security Constraints

When planning the investment in Microgrids (MGs), usually static security constraints are included to ensure their resilience and ability to operate in islanded mode. However, unscheduled islanding events may trigger cascading disconnections of Distributed Energy Resources (DERs) inside the MG due to the transient response, leading to a partial or full loss of load. In this paper, a min-max-min, hybrid, stochastic-robust investment planning model is proposed to obtain a resilient MG considering both High-Impact-Low-Frequency (HILF) and Low-Impact-High-Frequency (LIHF) uncertainties. The HILF uncertainty pertains to the unscheduled islanding of the MG after a disastrous event, and the LIHF uncertainty relates to correlated loads and DER generation, characterized by a set of scenarios. The MG resilience under both types of uncertainty is ensured by incorporating static and transient islanding constraints into the proposed investment model. The inclusion of transient response constraints leads to a min-max-min problem with a non-linear dynamic frequency response model that cannot be solved directly by available optimization tools. Thus, in this paper, a three-stage solution approach is proposed to find the optimal investment plan. The performance of the proposed algorithm is tested on the CIGRE 18-node distribution network.

Pre-Event Two-Stage Proactive Control for Enhanced Distribution System Resiliency

Recent advancements in prediction technologies have motivated the power distribution utilities to actively utilize forecasts to minimize the impact of high-impact low frequency (HILF) events. Accurate forecasting coupled with the past operational experiences potentially enables pre-event control, aiming to minimize the impact on the system in a network with finitely large numbers of automatic and manually operated control devices. Impacts to the critical loads (CLs) are minimized when the network is appropriately reconfigured before the event strikes. However, predictions are not perfectly accurate, and given limited accuracy with ever-changing weather forecasts, control actions are required to be constantly updated until the event has passed through. Once the events are predicted with high enough confidence and the necessary reconfiguration strategy has been identified, the manually operable switches must be configured significantly ahead of event landfall to ensure the operational crews’ safe return from potentially hazardous zones. Given limited resource availability and requisite manual switching operations, some loads would also have to be deenergized, which could be alleviated if those loads remain connected through remotely operable switches until minutes before the event makes the landfall. The proposed two-stage control framework with a necessary mathematical formulation facilitates the same. Furthermore, the proposed framework facilitates continuous corrective action based on available lead time. The developed proactive control framework is demonstrated using a modified IEEE 123-Node system model and a real-world isolated μ-grid based on the Cordova Electric Cooperative system with superior performance results.

Pengaruh Ketebalan Material Terhadap Shielding Effectiveness pada Frekuensi Rendah

Today, the need for electronic devices with smaller and more compact dimensions integrating many functions is increasing. At the same time, the need for ubiquitous processor speed, clock, data rate, and wireless connectivity is also increasing. This increase in demand also results in an increase in electromagnetic interference (EMI) in the environment. Although rare, High-Impact, Low-Frequency (HILF) events have the potential to have a deleterious impact on the electric power system. In this study, an analysis of shielding effectiveness (SE) was carried out at low frequencies when the thickness of the shielding material was varied. The materials used in this research are aluminum sheet and aluminum foil, and they combine their thickness through a single layer or double layer scheme. The thickness of the shielding material affects the value of shielding effectiveness; as evidenced when the thickness of the material is increased to 2 times, an increase in the value of shielding effectiveness reaches 207%. The use of double layers shows an increase in shielding effectiveness which is better than increasing the thickness of the material

Power Systems Resilience Metrics: A Comprehensive Review of Challenges and Outlook

Recently, there has been a focus on natural and man-made disasters with a high-impact low-frequency (HILF) property in electric power systems. A power system must be built with “resilience” or the ability to withstand, adapt and recover from disasters. The resilience metrics (RMs) are tools to measure the resilience level of a power system, normally employed for resilience cost–benefit in planning and operation. While numerous RMs have been presented in the power system literature; there is still a lack of comprehensive framework regarding the different types of the RMs in the electric power system, and existing frameworks have essential shortcomings. In this paper, after an extensive overview of the literature, a conceptual framework is suggested to identify the key variables, factors and ideas of RMs in power systems and define their relationships. The proposed framework is compared with the existing ones, and existing power system RMs are also allocated to the framework’s groups to validate the inclusivity and usefulness of the proposed framework, as a tool for academic and industrial researchers to choose the most appropriate RM in different power system problems and pinpoint the potential need for the future metrics.

Trial Implementation of a Multihazard Risk Assessment Framework for High-Impact Low-Frequency Power Grid Events

The Pacific Northwest National Laboratory developed a risk framework for modeling high-impact, low-frequency power grid events to support risk-informed decisions. In this paper, we briefly recap the framework and demonstrate its implementation for seismic and geomagnetic hazards using a benchmark reliability test system. We describe integration of a collection of models implemented to perform hazard analysis, fragility evaluation, consequence estimation, and postevent restoration. We demonstrate the value of the framework as a multihazard power grid risk assessment and management tool. The research will benefit transmission planners and emergency planners by improving their ability to maintain a resilient grid infrastructure against impacts from major events.

Coordinated attacks on electric power systems in a cyber-physical environment

With increasing terrorism and sabotage activities, the power grid is becoming more vulnerable to various kinds of cyber and physical attacks. Coordination between the attacks could bring higher impacts on the power system, as evidenced by the 2015 Ukrainian power system cyberattack. There is limited study in existing literature about possible coordinated attack scenarios and the detailed mathematical modeling of them. To prevent future coordinated attacks against power systems, in this paper the cyber-physical security of the power system is analyzed and probable coordinated attack scenarios are proposed. Two typical attack coordination examples are studied in detail: the coordination between load redistribution (LR) attack and attacking generators; and the coordination between LR attack and attacking lines. They are formulated as bilevel optimization problems, where the attacker at the upper level aims to maximize the load curtailment while the defender at the lower level makes an effort to reduce the load curtailment. The case studies conducted based on a modified IEEE 14-bus system demonstrate the potential damaging effects of the coordinated attacks. And it is shown that coordinated attacks could cause higher load curtailment than the standalone attacks. This study can provide meaningful insights on how to prevent and mitigate such high-impact, low-frequency (HILF) coordinated attacks.

Controlled Pilot Study of High-Impact Low-Frequency Exercise on Bone Loss and Vital-Sign Stabilization in Adolescents With Eating Disorders

PurposeAdolescents with anorexia nervosa (AN) face an increased lifetime risk of bone fragility. This randomized controlled study examined the efficacy and safety of a high-impact activity program on markers of bone turnover and stabilization of vital signs (VSS). MethodsForty-one hospitalized adolescents with AN were randomly assigned to routine care or routine care plus 20 jumps twice daily. Bone markers were measured at baseline days 1–3 (T1), days 4–6 (T2), and days 7–9 (T3). The primary outcome was change in bone-specific alkaline phosphatase (BSAP) at T3 adjusted for BSAP and % median body mass index at T1. Secondary outcomes were serum N-telopeptide (NTX) and osteocalcin at T3. Safety was determined by comparing weight gain, time to VSS and length of stay for each group. ResultsBSAP, NTX, or osteocalcin did not differ between groups at baseline or at T3. BSAP and NTX at T3 were not associated with group of enrollment or % median body mass index. VSS was significantly reduced in the intervention group compared with the control group (11.6 ± 5.7 days vs. 17 ± 10.5 days, p = .049). There was no significant difference in weight gain or length of stay between groups. ConclusionsTwice-daily jumping activity failed to influence markers of bone turnover in adolescents with AN but was well tolerated, shortened time to vital-sign stabilization and did not slow weight gain.

Meeting Brings Together Industry and Government Space Weather Interests

With the Sun finally becoming more active after a long period of quiet and with concerns growing about the integrity of U.S. and international electric power grids and infrastructure, the Fourth NOAA Space Weather Prediction Center (SWPC)/Commercial Space Weather Interest Group (CSWIG) Summit was convened on 29 April 2010 in Boulder, Colo., in conjunction with the 2010 Space Weather Workshop (SWW). The summit brought together industry and government space weather experts. Devrie Intriligator (Carmel Research Center, Inc.) and W. Kent Tobiska (Space Environment Technologies) cochaired the meeting. During the summit, Thomas Bogdan, director of NOAA’s SWPC, summarized the current status of his organization and its fiscal outlook. SWPC continues to develop under the National Weather Service with increasing budgets, hiring, and training of forecasters. In addition, President Obama’s fiscal year 2011 proposed budget includes $9.5 million for NOAA’s Deep Space Climate Observatory (DSCOVR) spacecraft. This mission, jointly funded by NOAA, the Department of Defense, and NASA, will be launched to an orbit at Lagrange point L1 to provide real-time solar wind and magnetic field parameters upstream of the Earth’s bow shock. The current budget plans for a December 2013 launch for DSCOVR. Participants discussed the importance of an earlier (e.g., early 2012 or sooner) DSCOVR launch because the very successful scientific and space weather monitor Advanced Composition Explorer (ACE) spacecraft currently at L1 is at times unable to return real-time solar wind parameters during large solar storms such as the October–November 2003 and December 2006 events. ACE, launched in 1997, has provided extremely valuable data for both real-time operations and in-depth studies of solar wind, interplanetary coronal mass ejections, solar energetic particles, and cosmic rays. However, ACE is beyond its design lifetime and is a single-point failure, since there is no backup source of substitute real-time L1 data. Bogdan further reported on SWPC’s interactions with the Federal Emergency Management Agency (FEMA) and FEMA administrator Craig Fugate, including a February 2010 workshop with their European Union counterparts entitled “Managing Critical Disasters in the Transatlantic Domain— The Case of a Geomagnetic Storm.” Bogdan noted Fugate’s recognition that space weather is among the potential threats known as high-impact, low-frequency (HILF) events, which occur rarely or with uncertain frequency but have the potential to cause severe damage. Tobiska and Intriligator reported on their meeting with Michael Bonadonna (Office of the Federal Coordinator for Meteorology). Bonadonna anticipated that the new National Space Weather Program Strategic Plan would soon be available online for comment at http://www.ofcm.gov/homepage/ text/pubs.htm. Participants also discussed the need for continuity of long-term data sets of importance to space environment climatology. One problem mentioned was that the SWPC Web pages will no longer include data from the Thule neutron monitor, which measures the number of high-energy particles bombarding Earth from space at Thule, Greenland, because the National Science Foundation has discontinued its funding. Louis Lanzerotti (New Jersey Institute of Technology) suggested a National Research Council study on longterm data sets, including their types and optimal locations. Last year, Admiral Conrad Lautenbacher (former NOAA administrator and now vice president for science programs at CSC) during his SWW presentation suggested the formation of a space weather association. Intriligator reported that Jerome Lafeuille (chief, Space-based Observing Division, World Meteorological Organization (WMO)) and Bruce Sumner (executive secretary, Association of HydroMeteorological Equipment Industry (HMEI)) suggested that HMEI could be a model for such an association. HMEI is composed of meteorological instrument builders, service providers, and forecasters; has official consultative status with WMO; and is housed in the WMO headquarters in Geneva, Switzerland.