Large portions of the electrical power grid are susceptible to component failures that when combined with certain other factors (extreme events), could cause cascading outages. Some of these outages can be severe enough to trigger brownouts and blackouts. There are a few established methodologies and tools for directly analyzing the hazards of cascading component outages over a longer time scale although there is a great deal of knowledge regarding the mitigation of the initial few failures that occur near the beginning of a cascade. Current power system tools have limited ability to perform detailed and accurate cascading-outage analysis, which could be computationally intensive.With the help of the Dynamic Contingency Analysis Tool (DCAT), power system planning engineers can evaluate the effects of severe contingencies and possible cascade events on their systems and connections in a more practically grounded manner. DCAT has several unique features: (1) detailed hybrid dynamic and steady-state analysis of power systems to mimic real-world cascading outages, (2) detailed modeling of protection systems embedded in the dynamic simulation, (3) simulation of corrective action after transients, (4) simulation of islanding, and (5) high-performance computing capability to simulate a large number of contingencies in a reasonable time. DCAT outputs will help find technically sound solutions to reduce the risk of cascading outages. This paper provides details of DCAT methodology and shows its capabilities with extreme events on real-world cases.

El Estudio de Resiliencia de la Red de Puerto Rico y Transiciones a Energia 100% Renovable (PR100) es un analisis integral basado en amplios aportes de las partes interesadas sobre posibles caminos para que Puerto Rico alcance su meta de 100% de energía renovable para 2050. PR100 fue un esfuerzo integrado que se baso en experiencia y capacidades de los laboratorios nacionales contribuyentes que exploraron posibles caminos para que Puerto Rico logre su objetivo de 100% de energía renovable en el largo plazo (para 2050), aumente la confiabilidad y la resiliencia en el plazo inmediato (dentro de los proximos anos), y trabajar hacia la justicia energetica. El proposito del estudio es brindar apoyo a las decisiones e informar las decisiones de inversion para los implementadores de la transicion energetica de Puerto Rico. See NREL/TP-6A20-88384 for the English translation of this report.

The extent of the damage to Puerto Rico from Hurricane Maria in September 2017 led to outages in electricity service that persisted for months. Power system operators attempting to restore critical facilities faced challenges on almost every front, from supply chain interruptions to the inaccessibility of key assets. After a disaster of this magnitude, it is critical, but challenging, to prioritize how limited resources are directed toward rebuilding and fortifying the electric power system. To inform these decisions, the U.S. Department of Energy funded efforts investigating methodologies to identify critical vulnerabilities to the Puerto Rican power system, and to provide data-driven recommendations on how to harden and operate the system for greater resilience. This work presents the Risk-based Contingency Analysis Tool (RCAT), a framework developed as a part of that resilience initiative. The framework can qualitatively and quantitatively describe the most critical system vulnerabilities with an understanding of both likelihood of occurrence and impact. It evaluates the effectiveness of candidate remediation strategies in reducing overall risk to the system from future hurricane events. This paper will describe RCAT, with an emphasis on how different modeling capabilities have been integrated along with probabilistic methods and analytical metrics to better describe risk.

Geomagnetic disturbances can greatly disrupt the power grid operation. This is caused by low-frequency changes in the earth’s magnetic field, which upon interaction with the deep earth conductivity induces a changing electric field at the earth’s surface. This in turn induces quasi-direct currents which have the potential to cause protective devices to operate, widespread damage to high-voltage transformers, or voltage collapse due to induced reactive power losses. While these impacts have been known since the 1940s, only recently have standards for GMD response been implemented. Because these standards are heavily based on models, it is important to understand when it is appropriate to make certain modeling assumptions. In this work, implicit modeling uncertainty is quantified for the purpose of enhanced decision making for disturbance impact mitigation. Considering electromagnetic models, modeling assumptions of non-uniform grounding, imbalanced operation, transformer saturation, and geomagnetically induced currents, voltage estimation values are analyzed. Statistical characteristics of modeling uncertainty are obtained by analysis of synthetically generated data. Results statistically characterize geomagnetic disturbances modeling uncertainty, providing an important tool for impact mitigation.

The foundation of the United States Department of Energy (DOE) Transmission Reliability research program was established 20 years ago by a series of commissioned white papers. Those white papers described the dramatic institutional and regulatory changes that the U.S. electricity transmission grid was undergoing at the time and articulated the technical challenges that these changes created. The challenges outlined in the white papers were the basis for the initial research goals of the DOE Transmission Reliability program. To a large extent, the reliability research needs outlined in the original white papers have now been met. As a result, now is an appropriate time to step back and review the technical challenges that the industry currently faces and to use those challenges as the basis for identifying the next set of targets for DOE's transmission-related research and development (R&D) programs.

Electric power resilience addresses preparedness of the system and its ability to cope with various hazards that can disrupt electricity. Resilience is the ability to anticipate, absorb, adapt to, and/or rapidly recover from a disruptive event. Many things can be done to improve the overall resilience of the power system. These include hardening critical components, increasing the modularity and interoperability of components (making quick replacement and restoration more efficient), and changing the overall architecture of the system to reduce the criticality of individual components. The system should be designed such that it has inherent properties of resilience: bend without breaking, fail with minimal disruption, and enable fast restoration and recovery. Resilient design concepts are rooted in the understanding that it is possible to design a system to a wide range of hazards, even those that are not enumerated or even imagined. This chapter provides a broad perspective of these issues.

Inertia in power systems plays an important role in maintaining the stability and reliability of the system by counteracting changes in frequency. However, the traditional sources of synchronous generation are being displaced by renewable resources, which often have no inherent inertia. This paper investigates the impact of reduced system inertia on several aspects of the dynamic stability of power systems, such as angular stability, primary frequency response, and oscillatory modes. This study is performed on a large-scale 2000 bus synthetic Texas model by selectively replacing synchronous generators with inverter-based generation resources. This paper also compares the analysis results obtained by the above-mentioned inertia-reduction approach of renewable integration with another approach in which the inertia constant of all synchronous generators is decreased. This paper demonstrates that only reducing the inertia of all synchronous generators in a system does not provide an accurate analysis of the challenges associated with the reduced system inertia caused by renewable integration.

This minitrack focuses on enhancing the resilience of future electric power infrastructure. Advanced technologies will require sophisticated methods for understanding how they can be incorporated into increasingly complex and dynamic infrastructure. Issues of resiliency and secure interoperability of future grid systems, and the associated computational and communication challenges associated with the power system, are examined.

Synchrophasor measurementsSynchrophasor measurements have been widely regarded as providing benefit to managing the electric power system. Various applicationsApplications have been deployed, ranging from improved situational awarenessSituational awareness to enhanced accuracy of dynamic models, enabled by improved measurements. This chapter will provide a brief introduction of the technology, how it evolved, and a summary of ongoing efforts by the US Department of Energy (DOE) to promote this technology for enhancing the reliabilityReliability of the power system. It will serve as an introduction to other chapters of this book, which will delve into greater details about synchrophasorSynchrophasor applicationsApplications that are improving power system planningPower system planning and operations.

The major power system blackouts that occurred in 1965, 1977, 1996, 1998, and 2003 notably involved incorrect relay operations. Most of these events occurred due to cascading failures which are partly deterministic and partly due to random aggravated circumstances. Traditional power system tools have the capability to analyze the first or the second event following a major disturbance. Dynamic Contingency Analysis Tool (DCAT) has been developed to overcome these shortcomings and analyze the cascading process for a number of what-if scenarios. Some of the unpredictable scenarios; intermittent generation as well as maloperation of protection system; have been analyzed in this paper. This paper also presents enhancements to DCAT that create chronological dispatch data to mimic the real world generation schedules due to load/generation intermittency and protection maloperation on cascading outages. This paper presents what-if scenarios for i) impact of chronological intermittent load and generation and ii) the consequences of unintended operation of protection relays on severity of outages caused due to severe contingencies.

This minitrack focuses on enhancing the resilience of future electric power infrastructure. Advanced technologies will require sophisticated methods for understanding how they can be incorporated into increasingly complex and dynamic infrastructure. This minitrack includes papers that examine issues of resiliency and secure interoperability of future grid systems, and the associated computational and communication challenges associated with the power system.

This paper develops a self-coherence method for detecting sustained oscillations using phasor measurement unit (PMU) data. Sustained oscillations decrease system performance and introduce potential reliability issues. Timely detection of the oscillations at an early stage provides the opportunity for taking remedial reaction. Using high-speed time-synchronized PMU data, this paper details a self-coherence method for detecting sustained oscillation, even when the oscillation amplitude is lower than ambient noise. Simulation and field measurement data are used to evaluate the proposed method's performance. It is shown that the proposed method can detect sustained oscillations and estimate oscillation frequencies with a low signal-to-noise ratio. Comparison with a power spectral density method also shows that the proposed self-coherence method performs better.

Utility energy storage media can be classified as fast– or slow–acting in reference to command and control response times ranging from milliseconds to less than a minute. World–wide, the generation and delivery of electric power typically relies on less fast–acting energy storage per unit of capacity than may be optimal. The present situation is expected to change as utility planners respond to new demands and begin to recognize that the near–instant availability of stored energy offers many high–value, cost–effective system benefits. This paper summarizes two application studies of superconducting magnetic energy storage (SMES) to illustrate some generation and transmission benefits of fast–acting storage. Emphasis is placed on the performance and economic criteria that can justify utility adoption and use of SMES options.

This paper proposes a redefinition of the power system quantities often said to be described by a synchro-phasor and measured by a phasor measurement unit. Problems with what are often called “synchronous phasor measurements” include the facts that they are not truly synchronous, and the quantity being measured is not truly a phasor. This paper proposes a new method of making measurements that overcomes these problems. It tests the proposed definitions and measurement methods with “synthetic” signals, and shows that the method provides understandable and consistent results.

The papers presented in this minitrack will address various aspects of these technical challenges.

This minitrack focuses on topics related to advanced concepts to enhance reliability, and security and trust issues associated with operating the future electric power infrastructure. The increasing reliance of the electric power industry on information technologies introduces a new class of cyber vulnerabilities and threats to the electric power infrastructure that are only beginning to be effectively addressed through common industry standards and best practices. In addition, we invite papers that examine issues of resiliency and secure interoperability of future grid systems. This minitrack will explore the application of these technologies that are being considered to enhance the reliability of the rapidly evolving modern electric power system, and the associated cyber security issues associated with these and related technologies.