Strategic Technology Research Backgrounder
Sensors and Operations
The Electric Power Research Institute, Inc. (EPRI) conducts research and development relating to the
generation, delivery and use of electricity for the benefit of the public.
With a staff of recognized industry experts, EPRI has established itself as a thought leader in the electric
sector worldwide. The organization is recognized for developing and demonstrating innovative
technologies, analyzing and enhancing current technologies, as well as seeking alternative methods to
produce and deliver electricity.
EPRI’s Technology Innovation (TI) organization has been integral in leading the development of key
technologies that have benefitted the electricity industry in numerous ways. The organization focuses on
stimulating innovation and developing enabling electricity technologies for adoption over a 5-10 year
period, or longer. For instance, EPRI research has lead to recognition of the global impact of mercury, the
development of a high-impact decontamination process and technologies to reduce carbon emissions
from coal generation.
The technology challenges that the electricity industry will face in achieving a low carbon future will
require groundbreaking technology development in a number of strategic areas. EPRI has identified 10
strategic programs that will be the focus of its longer term research efforts from 2009 and beyond. One of
the 10 is described here.
Sensors and Operations
Current Situation
What is the current state of the art?
Sensors are used across many industries to measure critical parameters including voltage, current,
temperature, moisture, pressure, vibration, sound, dissolved gases, mechanical stress and strain, among
others. In recent years the automobile industry and other consumer markets have also seen a significant
increase in sensor applications.
In the auto industry, for example, sensors have been extensively applied to monitor and control the
powertrain, chassis, and automobile body. Each new vehicle typically employs over one hundred different
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sensors. Operating under relatively severe conditions that include temperatures from 40 C to 125 C,
vibration and shock impact, the sensors meet requirements of accuracy, reliability, interchangeability and
cost.
Presently, sensors installed in power delivery systems are primarily limited to voltage and current sensing
devices, such as current and potential transformers and transducers, for metering, protection and control.
Sensors are not widely deployed in the power delivery sector for condition monitoring purposes. In most
fossil-fueled power plant facilities, the majority of sensors were specified based on process control
requirements, with little emphasis on detecting component degradation. Because many power plant
components have been in service for years, condition monitoring has become more important in order to
maintain equipment reliability, necessitating the use of vibration sensors, strain gauges, temperature
detection and other sensors.
Sensor technology has benefited tremendously in recent years from advancements in semiconductors,
fiber optics, optoelectronics, material science and network and communications. Sensors are smaller,
less costly and more reliable, with more smart functionality. Some sensors offer an integrated solution
with “on-board” sensing, signal conditioning and microprocessor capability on one chip. However,
continued improvements are generally needed in four areas: sensor reliability, cost, ease of installation
and maintenance and ability to manage the data gathered.
Why is EPRI investing in this area?
The electric industry is grappling with often conflicting challenges of minimizing the costs of operating and
maintaining the power infrastructure, while maintaining high levels of reliability. As the power
infrastructure ages, it must not only support existing demands, but also accommodate carbon reducing
technologies such as renewable energy, demand response, energy storage, and plug-in hybrid electric
vehicles. To do this, the infrastructure must operate more efficiently while it is transformed into an
enabling infrastructure for these carbon reduction technologies.
The Opportunity
What are the potential superior innovations?
Wide deployment of sensors for condition monitoring could change the way that the power grid and power
plant equipment are operated and maintained. A variety of advanced sensor technologies may help
achieve this functionality.
For example, a recent EPRI discovery in the measurement of hydrogen gas using metal insulated
semiconductor (MIS) chips could enable early, low-cost detection of hydrogen in oil-filled components
such as transformers, load tap changers and cables. These components permeate the entire power
delivery system. With this technology, sensor-based condition monitoring has the potential to significantly
change substation and transmission line maintenance.
In another EPRI project, an innovative sensor-based approach to overhead transmission line inspection
has been selected for development and demonstration. This approach includes use of an array of
wireless and wired sensors that relays information back to a data center through a communication hub on
nearby structures. Data may be collected via an unmanned airborne vehicle, manned aerial vehicle, or
line crawler robot.
EPRI was also involved in initiating a project that could change the way that maintenance data is
interpreted and acted upon. A backscatter leakage current monitoring technique is currently being
deployed to monitor insulators at a first set of substations and transmission lines operated by seven
utilities. This new system will enable optimal scheduling of insulator washing, warn system operators of
impending adverse events, help personnel perform forensic evaluations after these events, and allow
designers to better dimension and select insulators for future applications.
Another promising technology area, wireless sensors, could offer a cost-effective way to gather muchneeded data from aging substation components. The information that these wireless sensors gathers may
significantly assist in decision making on refurbishment and replacement, as well as increase worker
safety through early identification of failing components. Many of these sensors will operate in remote
locations or locations where provision of electric power for the sensors is difficult or impossible.
An evolving concept called “swarm intelligence” will encompass advanced sensor technology. Swarm
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intelligence is an umbrella term for an interconnected electricity network that will use new machine
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. Swarm intelligence is an umbrella term for a future awake, responsive, adaptive, stigmergic, selfhealing, price-smart, eco-friendly, efficient, real-time, flexible, and interconnected electricity network
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intelligence and communication technologies for enhanced operational command and control of the
distribution and use of energy. When realized, this concept could enhance real-time monitoring and
control of power system conditions; could increase adaptive intelligence, automation, and carrying
capacity of the power delivery system; and may improve the reliability and quality of power at the point of
use.
To process and interpret all of the data generated by these advanced sensors, operation and
maintenance personnel could work at yet-to-be-designed centralized equipment monitoring control rooms
across the country. Operators and analysts will interpret data there, instead of in the field, and make
optimal operation and maintenance decisions on a local and regional basis.
How could this research change the industry?
The ability to monitor the performance and condition of critical equipment – both power generation and
power delivery equipment – could enable a fundamental shift from traditional time-based/usage-based
maintenance to condition-based maintenance. In the latter scenario, equipment condition data are
continuously collected through sensors. Data analysis is performed as anomalies are identified either
through local data processing or at a centralized monitoring facility through advanced pattern recognition
tools. Maintenance actions are then executed just in time, deferring unnecessary maintenance, avoiding
component failure and making best use of existing assets. Simultaneously, on the power grid, real-time
data on equipment condition, and the potential risk of failure, enables better informed system operation.
Widespread adoption of sensors at power generators and on the power delivery system could have a
profound effect on the most asset intensive industry in the world. Knowledge of weak points in the power
delivery system, via sensor-based condition monitoring, could make deterministic methods of operating
the power system obsolete. Probabilistic reliability analysis, armed with sensor data, can enable stable,
safe, reliable operation of the power system closer to its limits. Performance of condition-based
monitoring on turbines, generators, and other rotating equipment, substation equipment as well as
transmission and distribution assets could mean fewer equipment failures.
Sensors will first be retrofitted across the grid and on critical power generation components, often using
wireless technology for cost effectiveness. New components will be equipped at the factory with various
embedded sensors, ready to send their data over standard communication systems. Sophisticated data
gathering systems will route equipment condition data from the sensors to central locations where it will
be displayed on advanced visualization systems. In some cases, sensor data will be processed on-board
the component through embedded systems, while only transmitting anomalous data to a central data
processing facility. At new central monitoring facilities across the country, operators and analysts will
interpret data, instead of in the field, and in cooperation with the monitored units make operation and
maintenance decisions on a local and regional basis.
What other applications are possible?
Application opportunities of advanced sensor technologies are quite broad and are limited only by
imagination. Applications are possible in virtually all sectors of the electric power industry. Applications in
other industries are almost limitless, as evidenced by major advances in sensor technology in the
automotive and consumer industries.
The Program
How are innovations being developed?
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This program will first develop a sensor roadmap for specific sectors of the electricity enterprise that will
identify the current state of the art, issues, gaps, as well as approaches to address the gaps. To do this,
the program will research and collect information on sensor developments within and outside of the
electric power industry. This project will increase awareness and knowledge of sensing technologies
developed for other applications that may be applicable to the power industry.
This program will then develop sensing elements that are unique to each sector of the electric power
industry. For example, for power delivery and utilization applications, research areas may include MIS gas
sensors, transmission line inspection of the future, underground cable sensors, and a cross-disciplinary
coolant temperature (CLT) sensor lab. In fossil-fueled power generation, research areas include a turbine
blade tip vibration monitoring system, high accuracy particulate mass monitoring, a mid-infrared (tunable
diode) laser, laser-based temperature measurement in coal gasification, and optical strain gauges. In
nuclear power generation, the primary research area is the development of Bragg sensors (optical fiber
sensing) for current and temperature measurement in nuclear power plants.
Selecting and developing sensing elements is only one aspect of creating sensor technologies for power
generation and delivery applications. The entire sensor system needs to be considered. This program will
ultimately address the additional needs of developing packing for the unique applications, such as high
electric and magnetic field, mechanical stresses, small locations, and environmental stresses; powering
the sensors and the associated sensor systems; communicating and storing the sensor information;
analyzing and visualizing the sensor information; and providing results to the correct parties and systems
to facilitate decision making.
A project is investigating how to provide electric power to operate wireless sensors installed in remote
locations such as transmission towers and in locations throughout a power plant. Advanced power
harvesting technologies will enable use of heat from hot transformers via thermoelectric cells, vibration
from transformers via piezoelectric devices, heat from solar options, or thermal energy from power plant
environments to power the sensors.
Additional efforts will address sensor data collection and communication. The program will ultimately
include research to develop crawling robots for line components to collect component information, as well
as use of swarm intelligence for the smart grid. Future projects may include development of algorithms,
alarms, and visualization approaches to maximize the benefit from sensor systems and address potential
information overload issues. Here, research areas will include visualization of nuclear equipment
monitoring information and a directional beam sensor control algorithm. Another future project may
develop the concept of an equipment monitoring control room for all areas in the power industry. Here,
research areas will include a survey of control center approaches, challenges and paths to
implementation; data network management, and management of the data.
When will applications occur?
The program will develop the sensor roadmaps in 2009, with updates in later years. Demonstration of
technologies is expected in 2010, including the MIS hydrogen transformer sensor and the overhead
transmission line inspection system, to name a few. Power harvesting technologies will be incorporated
into sensors as they are developed.
Value
What are anticipated costs and benefits?
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Through the use of condition-based maintenance, advanced sensor technology has the potential to help
utilities improve power grid reliability by avoiding unplanned outages. Utilities may be able to reduce
maintenance costs by providing “just in time” maintenance, gathering information remotely rather than
dispatching personnel into the field, and avoiding equipment replacement costs due to catastrophic
failure. Sensors also facilitate forensic analysis following failures. An added benefit is improved operating
efficiency by better utilizing generation and delivery assets via knowledge of component condition.
Advanced sensor technology could change the way in which the power delivery grid is operated by
moving from a deterministic approach to a probabilistic approach based on sensor information. Utilities
may be able to extend the life of existing power generation and delivery assets via improved knowledge
of their condition. Better informed run/refurbish/replace decisions for power generation and delivery
assets could also result from condition-based monitoring. This research also helps address the loss of
institutional knowledge about power generation and delivery asset maintenance by centralizing data
interpretation in equipment monitoring control rooms. Of equal importance, advanced sensor technology
helps accommodate – and enable efficient operation and maintenance of – carbon reduction technologies
such as renewable energy, demand response, energy storage and plug-in hybrid electric vehicles.
About EPRI
The Electric Power Research Institute, Inc. (EPRI, www.epri.com) conducts research and development
relating to the generation, delivery and use of electricity for the benefit of the public. An independent,
nonprofit organization, EPRI brings together experts from academia and industry as well as its own
scientists and engineers to help address challenges in electricity generation, delivery and use, including
health, safety and the environment. EPRI's members represent more than 90 percent of the electricity
generated and delivered in the United States, and international participation extends to 40 countries.
EPRI's principal offices and laboratories are located in Palo Alto, Calif.; Charlotte, N.C.; Knoxville, Tenn.;
and Lenox, Mass.
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Contact:
Don Kintner
EPRI
Manager, Communications
dkintner@epri.com
704-595-2006
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