Papers discussing DFA Technology
Texas Electric Cooperative 35th Annual Engineering Conference and Exhibit Show
Renaissance Austin Hotel
22 September 2017
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.
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.
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).
Presented to the 70th Annual Conference for Protective Relay Engineers, Texas A&M University, College Station, Texas
4 April 2017
- Technology background
- Examples from utility systems
- Medium voltage
- Low voltage
- Application to industrial environments
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.
Improving Management of Distribution Lines under Constrained Commercial Conditions using Innovative New Technology
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.
Innovative new technology to support a commercial and operational response
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.
Sound commercial and operational responses now to hand from a timely innovation
With increasing regulatory scrutiny, New Zealand distribution lines businesses are now facing a time of budgetry austerity and increasing pressure to improve asset management knowledge and practice.
A newly-released but long-standing technology called Distribution Fault Anticipation (‘DFA’) is being offered to the Industry under a unique companion implementation and consulting package.
Unlike any other technology in concept or contribution, the DFA implementation model offers innovations that address a great many of the commercial challenges facing the distribution lines industry. The technology provide an effective means to identify developing faults and manage asset degradation throughout the asset lifecycle, thus providing lines companies and Asset Managers a clear step change to a new phase in the evolution of Asset Management practice globally.
New to New Zealand, the adoption of DFA presents an opportunity to progress from the reactive corrective maintenance practices that have been traditionally employed to enable preventative maintenance on MV lines to avoid unplanned outages. Providing the unique ability to anticipate many faults before they have an impact on customers and feeder reliability, DFA/HiZ offers the following advantages and benefits:
- Improved safety for staff and the public.
- Improved efficiency (reduced cost) of field line repairs (reduced OPEX).
- Faster response to line faults by field crew (increased network availability).
- Network risk reduction – especially bushfire and electrocution risk.
- Increased asset life and improved asset management decision-making (more targeted and effective Capex investment).
- Improved quality of supply.
- Improved customer satisfaction.
- Improved senior management regulatory reporting ability.
- Demonstrable evidence of appropriate, measured and targeted investment based on pin-point determination of asset fitness within the asset lifecycle curve.
Implementation of DFA/HiZ provides a range of other accessible logged data and information plus many of the features of a digital fault recorder providing additional functionality and capability to analyse customer complaints and distribution feeder performance
Electric distribution utilities generally operate circuits in a reactive mode, responding and making repairs after outages occur. They perform periodic maintenance on certain equipment, such as capacitor banks, but most apparatus (e.g., connectors, insulators, service transformers) are numerous, long-lived, and geographically dispersed, making inspection resource-intensive. It would be preferable to make repairs proactively before outages occur, but utilities lack information that enables this. Recent “smart grid” technologies restore service more rapidly after outages occur yet remain reactive.
Working closely with the Electric Power Research Institute (EPRI), Texas A&M University researchers collected and analyzed an extensive library of high-fidelity current and voltage waveform data from more than 70 in-service circuits. They discovered waveform signatures caused by nascent failures of line apparatus and in the process validated the notion that apparatus often deteriorate over time before failing. As a result, researchers demonstrated numerous cases where detecting incipient failures enabled utilities to avoid outages. In some cases, utilities also were able to schedule corrective actions during normal working hours and in favorable weather, rather than responding to outages in adverse conditions (e.g., storms, nights), thereby improving efficiency and crew safety.
Researchers have developed algorithms to characterize circuit health and events based on high-fidelity data digitized by substation-installed devices. On-line algorithms deliver real-time information to improve awareness of circuit conditions, thereby enabling improved reliability and operations. This enables a move away from reactive operations and toward condition-based approaches.
Multiple electric distribution utilities have participated in multi-year trials of the technology. Their experience includes detection of incipient failures, improved response to vague customer problems (e.g. flickering lights, lights out), and prevention of faults. This paper discusses the technology and relies on case studies illustrative of events on real circuits and of how personnel can use improved system awareness to better manage assets and improve operations.