Lisa Beard

Field study of dispersion in a heterogeneous aquifer: 1. Overview and site description

Results are presented for a large-scale natural gradient tracer experiment conducted in a heterogeneous alluvial aquifer at a site near Columbus, Mississippi. The study was initiated with a 48-hour pulse injection of 10 m3 of groundwater containing bromide and three organic tracers (pentaflourobenzoic acid, o-trifluoromethylbenzoic acid, and 2,6-diflourobenzoic acid). Over a 20-month period, seven comprehensive samplings of the tracer plume were performed at approximately 1- to 4-month intervals using an extensive three-dimensional sampling well network. The dominant feature of the tracer plume that evolved during the study was the highly asymmetric concentration distribution in the longitudinal direction. This asymmetry was produced by accelerating groundwater flow along the plume travel path that, in turn, resulted from an approximate 2-order-of-magnitude increase in the mean hydraulic conductivity between the near-field and far-field regions of the site. The Columbus study is distinct from previous natural gradient experiments because of the extreme heterogeneity of the aquifer, the large-scale spatial variations in groundwater velocity, and the extensive set of hydraulic conductivity measurements for the aquifer.

Wide-area Frequency Based Event Location Estimation

This paper discusses the latest developments in wide-area frequency-based event location using FNET. FNET, meaning ldquoInternet based frequency monitoring networkrdquo, is a low cost and quickly deployable wide-area frequency measurement system with high dynamic accuracy. This project demonstrated the feasibility of using information from FNET to estimate the location of events in the electric grid. An on-line real time event detection tool using least squares methods was developed and tested on data from FNET. This paper outlines the methods used along with an examination of implementation feasibility.

Recent experience with a hybrid SCADA/PMU on-line state estimator

PMU devices are expected to grow in number from a few to several hundreds in the next five years. Some relays are already global positioning system-capable and could provide the same type of data as any PMU. This introduces a new paradigm of very fast accurate synchrophasor measurements from across the grid in real-time that augment and parallel existing slower SCADA measurements. Control center applications will benefit from this PMU data; for example, use of PMU data in state estimation is expected to improve accuracy and robustness, which in turn will result in more timely and accurate N-1 security analysis, resulting in an overall improvement of grid system reliability and security. This paper describes results from a recent implementation of this technology, the benefits and future work.

Wide area power system visualization using real-time synchrophasor measurements

It is critically important for improving the wide area situation awareness of the operators or operational engineers and regional reliability coordinators of a large interconnected systems to prevent large scale cascading system outages. This paper describes an advanced wide-area power system visualization application (WAPSVA) for the real-time reliability monitoring using real-time synchrophasor measurements and for the post event analysis using historical synchrophasor measurements related to the large system events. This paper also presents a very useful feature which will allow a large number of users to perform the near real-time event replay a few seconds after a new large event occurs in a large interconnected power system. This wide area power system visualization application can also show the location, magnitude and the related event message on the visualization display in real-time by integration with the on-line event triggering and location of disturbance applications. The main performance challenges of the visualization application include how to efficiently handle large volume of synchrophasor measurements and how to support large number of concurrent users for performing real-time reliability monitoring, near real-time event replay or post event analysis. This paper describes the technologies used in the WAPSVA application to meet the challenging performance requirements. The technologies include the memory residence object oriented database, event oriented database and Smart Client. The system architecture, the technical approaches and the solution algorithms used in this visualization application are described in detail. This visualization application has been integrated and tested using the simulated synchrophasor measurements and the real time synchrophasor measurements of Eastern Interconnections at the TVA Super Phasor Data Concentrator (SPDC). The performance of the initial testing is very encouraging and the test results are presented in this paper.

Development of TVA SuperPDC: Phasor applications, tools, and event replay

With information and measurement technology evolving rapidly within the electric power industry, wide-area measurement, monitoring and control (WAMC) is deemed to be the key technology to improve power system reliability. Guided by this vision, the North American SynchroPhasor Initiative (NASPI) is a nation-wide project that collaborate various resources to build the infrastructure of WAMC across North American. As part of NASPI, Tennessee Valley Authority (TVA) is developing super phasor data concentrator (SuperPDC) which is the infrastructure hosting different measurement resources and providing platform for numerous WAMC applications, both real-time and none real-time. This paper outlines the SuperPDC architecture and demonstrates some real-time and close to real-time applications, developed by TVA and Virginia Tech based on SupersPDC platform.

Monitoring the North American interconnections at distribution level

The North American Frequency Monitoring Network (FNET) is a wide-area measurement system that monitors the North American Interconnections at distribution voltage level. A situational awareness system has been implemented on the server located at Virginia Tech to detect and analyze power system disturbances in near-real time. This paper demonstrates the viability of monitoring bulk transmission systems at a very low voltage level by discussing several major disturbances in the Eastern Interconnection (EI) observed by FNET. Important parameters of power systems, such as frequency, voltage and phase angle, are examined to understand system behavior during disturbances. The recordings and analysis show that a great deal of valuable information about dynamics in transmission systems can be obtained at a lower voltage level. The disturbance location estimation is also analyzed as an application of the distribution-level measurements.

Wide-area measurements of three nOrth America interconnections at distribution level

The North American frequency monitoring network (FNET) takes GPS-synchronized wide-area measurements in a low-cost, easily deployable manner at the 120 V distribution level. A situational awareness system has been implemented on the server located at Virginia Tech to detect and analyze power system disturbances in near-real time. Power system disturbances are examined in this paper based on wide-area frequency, voltage and phase angle data from FNET. Frequency characteristics of events in three major North America power Interconnections are investigated. Typical frequency patterns of generation loss and load drop events are analyzed for the Eastern Interconnection (EI), the Western Electricity Coordinating Council system (WECC), and the Electric Reliability Council of Texas system (ERCOT). Several significant disturbances in the EI are also discussed. The recordings and analysis show that a great deal of valuable information about dynamics in bulk transmission systems can be obtained at a lower voltage level.

The electric power industry and climate change: U.S. research needs

Research needs for the US electric power industry to address global climate change are summarized. The research addresses both mitigation, how the industry contributes to climate change, and adaptation, how the industry itself is affected by climate change.