EEI 2018 Edison Award Nomination submitted
by Indianapolis Power & Light Company for the
IPL FIBER OPTIC TEMPERATURE MONITORING SYSTEM
After experiencing challenging media coverage and public outcry over safety concerns following cable fires and dislodged manhole covers in its downtown network, Indianapolis Power & Light Company (IPL) became proactive in discovering and employing an innovative solution that has shown remarkable success over the past two years.
By taking technology used in the oil pipeline industry, IPL partnered with Texas-based Fiber Optic Pipeline Solutions to be the first electric utility ever to use a distributed temperature sensing (DTS) system to monitor external high-temperature threats in an underground network secondary grid. This development is a game changer in the electric utility space, and has the far-reaching potential of enhancing safety for any large metropolitan area that utilizes both electricity and steam in its network.
We proudly submit our nomination for the 2018 Edison Award, touting the results of our Fiber Optic Temperature Monitoring System.
The following pages will demonstrate how this innovation helped IPL improve the safety and reliability of the fundamental life element we deliver: energy for 490,000 customers and more than 28 million visitors – people who expect to be able to turn on their lights and have power, while in the city of Indianapolis.
Steam. It may seem like an antiquated heat source. But here in Indianapolis major businesses, hospitals and corporations use it each and every day. In fact, Indianapolis has one of the largest steam distribution systems in the U.S.
For many years, steam was a contributing factor in causing considerable safety issues in the heart of downtown, and near IPL’s underground infrastructure and power cables.
Steam was corroding our cables, degrading their outer jackets and prematurely aging them. Steam – with its propensity to deform conduit if exposed long enough to leaks, was indeed an issue we needed to tackle. In the past, we relied on a steam company’s annual thermal survey and our own crews, who would report any heat issues encountered during routine inspections. But those two tactics – though helpful – were not comprehensive, leaving heat issues to go undetected for a year or more.
Indianapolis Power & Light (IPL) needed to be more proactive to address steam issues in our city. We needed to look beyond the status quo and reach for an innovative solution that would improve safety for our employees, city residents and visitors.
That solution came in the form of a distributed temperature sensing (DTS) system – technology that had never before been used in the electric utility underground network space.
In late 2015, IPL partnered with Fiber Optic Pipeline Solutions (FiOps) to devise a DTS system that would enable IPL to proactively monitor external high-temperature threats from the steam distribution system in real time. By June 2016, IPL and FiOPS installed and commissioned a DTS pilot to evaluate the effectiveness of the system.
FiOps introduced our team to its DTS system, and from there, our team’s vision began the steps toward reality.
LIOS DTS Controller collects the data and analyzes\interoperates the data and sends the results to the servers which act as the historians.
How DTS Works
A typical DTS system contains three components: DTS controller, standard multimode fiber-optic cable and a server to store the data. The DTS controller turns the fiber-optic cable into a linear sensor that has a spatial resolution of approximately 3.28-ft (1-m) increments with an accuracy of ±1.8°F (±1°C).
How the DTS controller measures the temperature is based on the principle of Raman scattering. Thermal
effects induce lattice oscillations in the glass fibers, which, in turn, cause light to be scattered back to the DTS controller. The DTS controller interprets two components of the backscatter, stokes and anti-stokes, to determine the temperature at any given point along the fiber. The time it takes for the backscatter to reach the DTS controller is used to calculate the precise location of the thermal event.
Once the DTS system was commissioned and on-line, this unprecedented system started delivering what we hoped.
Hot spots and the beginnings of a steam leak were detected in one area in real time; issues of which both IPL and the steam company had not previously been made aware. In July of 2016, the temperature in one particular area had risen to more than 135F° (75.2C°) and was climbing steadily. The DTS system alerted IPL to the situation so the utility and steam company could address the issue in a timely manner before any damage was done to IPL’s infrastructure and cables.
A month later, IPL’s senior management gave the engineering team the go-ahead to install additional routes for the DTS system in the secondary network to monitor threats from steam.
By the close of 2017, IPL had installed four radial fiber-optic routes consisting of approximately 37,000 ft (11,277 m), which is currently monitoring about 50 percent of the steam system, as it relates to IPL’s infrastructure. In addition, IPL installed a second DTS controller at a substation near the downtown network secondary grid for redundancy purposes. Data from the two DTS controllers is stored on two servers at separate locations.
HOW DTS IS IMPROVING IPL’S SAFETY AND RELIABILITY
Much has been learned from the application of the DTS system. In addition to monitoring for deltas in temperatures due to possible steam leaks, we have learned that the DTS can detect secondary fires and cable faults.
On June 23, 2017, the DTS system detected a manhole fire in the downtown network. Within 7 minutes and 30 seconds, the temperature rose from 35.19°C to over 165.87°C. This rapid temperature spike, alerted us immediately of the situation and pinpointed exactly where the problem area was in our network.
IPL’s mission is “Improving lives by providing safe, reliable and affordable energy solutions in the community we serve.” Having the DTS system enables IPL to monitor situations in the network and proactively investigate potential high temperature events. This monitoring helps to limit potential network events and unforeseen high temperature situations.
In addition, IPL meets with the local steam company on a regular basis to discuss reports of steam anomalies within the Indianapolis Central Business District. In 2012 when the monthly meetings began there were 57 anomalies listed in a multi-page report. Currently there are 24 steam anomalies on a single-page report. Over the last 12-months this number has been as low as 19.
The DTS system has proven to be a very effective technology for use in secondary networks. Employing DTS and fiber optic cable eliminates the need for thousands of individual sensors. With this innovative approach to monitoring temperature changes throughout the underground infrastructure, IPL customers, guests to Indianapolis and our employees can live, visit and enjoy downtown Indianapolis
-knowing there is a safe and reliable underground network system beneath their every step. IPL
(Left) In downtown Indianapolis, steam could be seen billowing from beneath the city’s infrastructure. What may look harmless to outside eyes, steam is actually evidence of the damage taking place underground. For years, steam was causing safety issues near IPL’s infrastructure and power cables. (Right) Police and firefighters on the scene following a downtown event, where a manhole was dislodged after a cable fire.
Enhanced view of network system with fiber optic route overlayed to show hot spot locations in relation to steam
line, some IPL facilities and DTS temperature status.
Indianapolis Power & Light Company provides retail electric service to more than 470,000 residential, commercial and industrial customers in Indianapolis, as well as portions of other Central Indiana communities surrounding Marion County. During its long history, IPL has supplied its customers with some of the lowest-cost, most reliable power in the country. For more information about the company, visit www.IPLpower.com.
This graph shows the distance between two manholes. As you can see, the temperature steadily increases from July 4 to July 30 from roughly 87°, at its lowest point to 140° at its highest.
Example of 350 kcmil Cu EPR 15 kV cable damaged by steam. This cable is at the end of useful life after only three years of service.Temperature trace from June 23, 2017. Within 7 minutes and 30 seconds the temperature rose from 95.34°F to 330.566°F which is indicative of a cable fire. The DTS system was able to alert IPL to the precise location of the cable fire.