Papers discussing DFA Technology
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.
This paper introduces a new and unique technology for the improved management of MV lines. The technology has recently completed a one year programme of review by a local asset management consulting company and is now in its rollout phase in the Australasian region using an innovative life-time support continued-relevance business case model.
Known as Distribution Fault Anticipation [“DFA”] technology it provides a quantum advance for MV line management by providing the user with information to assist the identification of faults even before they cause interruptions. DFA has been demonstrated to detect a wide variety of developing line failures, pre-failures, and other events in real time, providing timely warnings to the asset owner to enable preventative actions.
An important outcome of this technology is that it can determine, characterise, and notify the occurrence of developing issues prior to these being known to the asset owner by conventional means.
Developed collaboratively over some 20 years at the request of the USA power industry and tested over hundreds of feeder-years of service, the techniques employed are such that they operate with extremely low false positive outcomes even in high noise environments, unlike other concepts employing defined level-based triggers. Importantly, the technology is inherently adaptable and remotely-upgradable as refinements are implemented.
The web-based DFA technology reports findings quickly in a simple-to-read code of characterised issues, along with associated timings and other information to determine the nominal type of fault and the location of the reported matter. Reports allow a clear understanding of the issue(s) immediately. Such details on likely fault and location have proven a major boon to DFA users in enhancing the safety and efficiency of standard operational responses, as well as offering a significant contribution to improved customer service delivery, improved regulated line performance statistics, and lowered operational costs.
The paper reviews the technology and assesses its contribution, both in the context of regulatory content and fundamentals of distribution Line Company operational and asset management objectives.
Application of Waveform Analytics for Improved Situational Awareness of Electric Distribution Feeders
Over the past several years, distribution utilities have invested heavily in installations of “smart-meter” advanced metering initiative (AMI) systems. Among the anticipated benefits of these systems, utilities with smart-meter deployments are generally able to quickly assess which portions of their systems are operating normally and which customers are experiencing an outage. Projects at multiple utilities have focused on integrating AMI information, along with traditional supervisory control and data acquisition data sources, into utility distribution management systems to improve situational awareness on distribution feeders. Despite the clear benefits each of these systems offer, their ability to provide utilities with broad awareness of events affecting the health and status of the distribution system is limited, and often reactive in nature. This paper presents never-before published cases observed in real-world field trials, detailing how integration of waveform analytics into utility operational practice leads to improved situational awareness.
Line capacitors are used ubiquitously for voltage regulation, power factor correction, and reactive power management on distribution circuits. Utility companies spend considerable money installing and maintaining these banks. Capacitor banks are widely known for experiencing internal short circuits, fuse operations, and other failure modes.
As part of ongoing projects at Texas A&M University, researchers have documented multiple, real-world failures and other improper behavior of line capacitors. They also have documented the unique electrical current and voltage waveforms signatures these failures produce, as measurable from conventional, substation-based current and potential transformers. The resulting database contains many examples of failures detectable by conventional utility inspection and testing practices, but also many examples of failures not detectable by those conventional methods. Some failure modes can have consequences more deleterious to system health than simple loss of voltage support, voltage balance, or reactive power support. Based on the field experience and library of electrical signatures, researchers have developed a system known as Distribution Fault Anticipation (DFA) technology, which detects and warns utilities about a variety of line apparatus failures and pre-failures, including those involving capacitors, thereby enabling system condition awareness and condition-based maintenance for circuit apparatus, including capacitor banks.
This paper presents selected case studies from operational circuits, and describes the benefit of using DFA technology to detect capacitor problems in their pre-failure state, enabling timely repair.
AVO NZ and Lord Power Equipment is planning to market Distribution Fault Anticipation (DFA) technology and has requested Terry Krieg, a Senior Affiliate of Lord Consulting to undertake an evaluation and an assessment of the suitability of the technology for Australasia using publicly available information sources.
The DFA technology is based on 30 years of research initially via EPRI1 in the US and more than 10 years of practical field trials involving more than 10 US power utilities. In that time, an extensive database of experience in distribution faults has been collected.
The DFA technology uses waveform analysis and pattern recognition of system events to determine precursor indications of hardware failure or interference with the distribution line from flora and fauna. The aim is that these indications of early contact with plants and animals may be detectable before the fault can result in damage to line hardware resulting in a protection operation (line outage), equipment damage or a fire start.