A Study of the Impact of Reduced Inertia in Power Systems

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

Process Control System Cyber Security Standards - An Overview

The use of cyber security standards can greatly assist in the protection of critical infrastructure by providing guidelines and requisite imperatives in the implementation of computer-controlled systems. These standards are most effective when the engineers and operators using the standards understand what each of the standards addresses and does not address. This paper provides a review and comparison of ten documents dealing with control system cyber security. It is not meant to be a complete treatment of all applicable standards; rather, this is an exemplary analysis showing the benefits of comparing and contrasting differing documents

Integration of distributed energy resources. The CERTS Microgrid Concept

Evolutionary changes in the regulatory and operational climate of traditional electric utilities and the emergence of smaller generating systems such as microturbines have opened new opportunities for on-site power generation by electricity users. In this context, distributed energy resources (DER)--small power generators typically located at users' sites where the energy (both electric and thermal) they generate is used--have emerged as a promising option to meet growing customer needs for electric power with an emphasis on reliability and power quality. The portfolio of DER includes generators, energy storage, load control, and, for certain classes of systems, advanced power electronic interfaces between the generators and the bulk power provider. This white paper proposes that the significant potential of smaller DER to meet customers' and utilities' needs can be best captured by organizing these resources into MicroGrids

A Risk-Based Framework for Power System Modeling to Improve Resilience to Extreme Events

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

CYP2C9*2 is associated with indomethacin treatment failure for patent ductus arteriosus

Aims: To identify clinical andgenetic factors associated with indomethacin treatment failure in preterm neonates with patent ductus arteriosus (PDA). Patients & Methods: This is a multicenter cohort study of 144 preterm infants (22-32 weeks gestational age) at three centers who received at least one treatment course of indomethacin for PDA. Indomethacin failure was defined as requiring subsequent surgical intervention. Results: In multivariate analysis, gestational age (AOR 0.76, 95% CI 0.60-0.96), surfactant use (AOR 9.77, 95% CI 1.15-83.26), and CYP2C9*2 (AOR 3.74; 95% CI 1.34-10.44) were each associated with indomethacin failure. Conclusion: Age, surfactant use, and CYP2C9*2 influence indomethacin treatment outcome in preterm infants with PDA. This combination of clinical and genetic factors may facilitate targeted indomethacin use for PDA