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Papers discussing DFA Technology

Improving Reliability and Safety of Electric Power Delivery Using DFA Technology

Summary

Line faults and device failures on distribution circuits can cause outages and unsafe conditions such as downed energized conductors. They also are a frequent cause of wildfires. Researchers with Texas A&M Engineering’s Power System Automation Laboratory have developed an advanced monitoring and diagnostic technology called Distribution Fault Anticipation (DFA). DFA provides 24/7 monitoring and automatic analysis of distribution circuit events. The result is enhanced situational awareness for operators, with automatic diagnosis of abnormal operations, detection of failing devices, and detection of incipient faults. Operating conditions that likely would result in catastrophic faults can often be detected, identified, located and repaired using actionable information. DFA technology has had extensive field testing and currently is in routine use by several utility companies, including Mid-South Synergy, an electric cooperative utility, headquartered in Navasota, Texas, USA. Mid-South has used DFA to discover, locate, and correct a significant number of line problems of which they otherwise were unaware. This paper provides a brief overview of the technology and then describes three such events that help illustrate specific benefits to reliability and to personnel and public safety. The purposes of the paper are to illustrate that current and voltage waveforms contain substantial untapped information regarding circuit conditions and to use one utility’s recent experiences to illustrate how using that information can improve reliability and safety.

Keywords

Incipient faults, failure prediction and diagnosis, operator situational awareness electric power reliability, public safety, wildfire/bushfire, power quality.

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Automated Waveform Characterization for Providing Situational Awareness to Distribution System Operators

21st Annual Georgia Tech Fault and Disturbance Analysis Conference

Georgia Tech, Atlanta, Georgia

April 30 – May 1, 2018

Abstract

For two decades, Texas A&M Engineering researchers have worked in an area that has come to be known as Distribution Fault Anticipation, or DFA. The DFA research program installed specialized waveform recorders on dozens of North American circuits. Multi-year installations have resulted in what is believed to be the largest database ever created of high-resolution waveform recordings for failures and other events on distribution circuits under normal operating conditions (i.e., not simulations, staged failures, or accelerated aging). Based upon that database, researchers have identified waveform characteristics unique to multiple types of failures and incipient failures on electric power distribution circuits and have created and tested automated algorithms and a system for reporting failures via web in near real-time.

This paper overviews DFA technology background and current capabilities, such as automatic, web-based characterization and reporting of faults, incipient failures, and other circuit phenomena of interest. It details selected examples of complex events in detail, including those where transient activity at one location on a circuit causes sympathetic response and failure at a different location. For example, internal arcing of a line capacitor caused the failure of a lightning arrester farther down the circuit. Another example details how contact by a kite string at one position on a circuit induced a total of three faults on the circuit, including one that was five miles from the point of kite string contact.

Application of DFA Technology for Improved Reliability and Operations

This paper was presented at the 2017 IEEE REPC conference April 23-26, 2017, in Columbus, Ohio, USA and published in the associated proceedings.

Abstract -- DFA Technology, developed by Texas A&M Engineering in collaboration with EPRI and the utility industry, provides operational visibility and awareness of distribution circuit events, based upon real-time, autonomous monitoring of substation-based CTs and PTs. DFA monitoring devices monitor current and voltage waveforms continuously, detect anomalies, infer circuit events that likely caused those anomalies, and report conditions such as faults and incipient failures via web interface. DFA does not require communications to reclosers, capacitor banks, AMI systems, or other devices downstream of the substation. Examples of detectable conditions include faultinduced conductor slap, pre-failure clamps and switches, problems with unmonitored capacitors, problems with unmonitored reclosers, and recurrent faults resulting from conditions such as cracked bushings. DFA technology provides advance notice of some faults and also helps diagnose vague symptoms and complaints.

Texas A&M Engineering manages an ongoing DFA field demonstration that involves more than sixty distribution circuits at eight Texas-based utility companies, six of which are rural electric cooperatives. Pedernales Electric Cooperative is one of those participants and, based on experiences gained during the demonstration project, plans to fit most of their 200 distribution circuits with DFA in the next three years.

Index Terms—Fault detection, fault location, distribution reliability, power distribution lines, power distribution faults, apparatus failures, incipient faults, smart grids.

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Mechanisms of Vegetation-Caused Faults on Electric Power Lines

Vegetation intrusion causes problems with electric power lines through a variety of mechanisms. Outage reporting systems typically include “vegetation” as a broad cause category for tracking outage statistics, but improved understanding of vegetation-related issues requires tracking of the precise root causes of vegetation events. This white paper overviews multiple vegetation-related mechanisms common to overhead power lines. It does not purport to examine every possible scenario.

Vegetation can interfere with secondary service conductors (i.e., less than 1 kV), primary distribution conductors (i.e., 1 kV through 35 kV), or transmission and sub-transmission conductors (i.e., above 35 kV). This white paper focuses on vegetation interfering with primary distribution conductors.

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Incipient Conditions on Electric Power Circuits

Incipient: adjective; beginning to develop or exist; beginning to come into being or to become apparent. (source: Merriam-Webster online)

A practical definition of an incipient condition on an electric power circuit is anything likely to cause a fault, outage, or other negative event in the future. A common misconception holds that incipient conditions manifest themselves only as low-amplitude electrical events, and conversely that high-amplitude electrical events do not represent incipient conditions. More than a decade of Distribution Fault Anticipation (DFA) field investigations demonstrates that this often is not true. Incipient conditions can manifest themselves as high-amplitude electrical events, although often in ways that conventional systems and processes fail to recognize as predictors of future events. Field experience demonstrates that an incipient condition may have any combination of the following characteristics:

  • It may or may not have caused past customer complaint(s).
  • It may or may not have caused past high-amplitude electrical event(s).
  • It may or may not have caused past conventional protection operation(s).
  • It may or may not have caused past outage(s).

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Transformational Network Technology, or simply just the Next Logical Steps for Asset Management

This paper is a developmental discussion about Transformational Technology from a positive asset management perspective. We often hear discussion and argument within the industry on the difficulties we now face from the impacts of new transformational technologies such as Solar PV, Electric Vehicles and Energy Storage but it’s interesting that all of these technologies are in fact older than the systems we operate.

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Improving Management of Distribution Lines under Constrained Commercial Conditions using Innovative New Technology

INTRODUCTION

The energy sector globally is one of the most important factors underpinning the world economy and relative competitiveness. Those countries rich in energy resources such as New Zealand and Australia have a significant advantage over many of their trading partners. Reliable and competitively priced energy supports business competiveness and lowers the cost of living, in turn helping to reduce the relative cost of labour.

In the Australian Government Energy White Paper (2014), a vision for the energy sector was defined as:

“Competitively priced and reliable energy supply to households, business and international markets through:

  • Competition that will improve consumer choice and put downward pressure on prices
  • The more productive use of energy to lower costs , improve energy use and stimulate economic growth
  • Investment to encourage innovation and energy resources development to grow jobs and exports.

In New Zealand power industry regulation is managed by the Commerce Commission. Historically, the power sector is viewed as exhibiting low levels of competition and the Commerce Commission aims to regulate to ensure the price and quality of energy benefits consumers.

The type of regulation applied to New Zealand electricity business including Transpower and the 17 non-consumer owned distribution business is described as “price-quality regulation” and a key aspect is the regulation of the prices that utilities can charge customers using a “CPI-x” formula approach. This means that prices, or more precisely, revenue is restricted to increasing at a rate that is less than inflation (or CPI1) by a factor of “-x”, determined periodically by the Regulator based on arguments from the utilities.

This CPI-x approach to revenue means that utilities are ever more focused on winning arguments to the Commerce Commission but also seeking ways to reduce operating costs in the long term.

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Managing Distribution Lines Companies under Increasing Regulatory & Budgetary Constraints:

Innovative new technology to support a commercial and operational response

Executive Summary

Recent decisions of Regulators in Australia and New Zealand indicate an increasing emphasis on reducing costs associated with managing transmission and distribution assets. A fundamental electricity industry regulatory objective, enshrined in Australian National Electricity legislation is the role of the AER to promote the efficient investment, operation and use of electricity services with the long-term interests of electricity consumers in mind. As a result of Regulator determinations, the industry is now facing a level of fiscal constraint that requires a consideration of alternative ways to manage specific asset classes in some cases.

In the past the Regulator has supported network investment arguments based on increasing network reliability and the reduction or maintenance of network average age. Australian utilities are now experiencing determinations from the AER that are clearly signalling that CAPEX and OPEX must be reduced in real terms (in some cases significantly) over the next regulatory periods. As a result the industry is now facing a level of fiscal constraint not experienced in past regulatory cycles. These determinations have proven painful indeed to all distribution lines companies, requiring a change in emphasis in asset management practices.

While many of the fundamentals of asset management for power utilities will remain the same, different approaches in the management of a number of asset classes may need to be considered to enable effective operation of a reliable and safe network under these changed fiscal constraints.

A new technology known as ‘Distribution Fault Anticipation’, coupled with a unique implementation  model, offers a timely means to manage this situation with significant benefits in reducing operating cost and increasing reliability of distribution networks. The paper discusses the technology and its contribution to effective asset management practice in organisations under major commercial pressure and fiscal constraint.

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