The electric utility industry is in a period of massive expansion amid corporate consolidations and mergers. Reliability is being legislated by the regulators and demand for power continually increases. It is a changing landscape.

The U.S. Department of Energy (DOE) forecasts that increased power consumption will require utilities to spend approximately $900 billion to increase their transmission and distribution facilities in the next 20 to 30 years. The economic slowdown may have delayed this a little, but it will not stop it.

In addition, utilities must expand and upgrade their existing facilities for this increased electric demand. Unfortunately, a large portion of those facilities were built 50 to 70 years ago and also should be replaced. DOE projects the cost to modernize will be more than $600 billion.

These figures show electric utilities are doing a great deal of construction despite reduced budgets and smaller work forces. As a result, utilities are continuously challenged to stretch those shrinking resources. They rely on technological advancements to give them the edge.

As-Built Drawings and LiDAR Surveys

One of those advancements is light detection and ranging (LiDAR) used for the management of network infrastructure and logistics. Those familiar with LiDAR tend to think of it as an aerial-based platform, but it is also available as a ground-based system.

Both the aerial- and ground-based methods use a laser combined with GPS and some form of inertial navigation system. They produce digital elevation models (DEMs) and digital terrain models (DTMs) made from ground reflections of everything in the path of the laser beam. LiDAR is often referred to as a laser survey, but it cannot be used for a legal boundary survey. In some parts of the country, one can get into trouble with various agencies for using “LiDAR” and “survey” in the same sentence, but seriously, LiDAR is revolutionizing the industry. This is especially true with an as-built laser survey, which provides an accurate record of the details of a facility in its current state.

Everything imaginable is recorded in a digital format when a LiDAR scan is taken. The digital format makes it easy to work with the LiDAR data. It can be imported, exported and manipulated by sophisticated programs, such as Power Line Systems' PLS-CADD, Pondera Engineers' TLCADD and Electric Power Research Institute's TLWorkstation. Applications like Autodesk's AutoCAD, ESRI's ArcView and other GIS software produce graphic tools to manage transmission assets.

However, the real trick is being able to distinguish what those millions of data points represent and generate a usable model.

In the hands of a skilled technician, the data creates a virtual representation that shows the foliage, bare earth, roadways, transmission lines, towers, poles, buildings, vehicles and substations. Transmission models have been improving by getting higher point densities from aerial-based LiDAR systems. These models require precise vectorized data to show the necessary details for representations of transmission line sway and sag under various loads and weather conditions. They are also able to identify tower types, pole placement, cable fixations, attachment points and even hardware, which have given rise to a new application for the assessment of existing facilities.

Lower and Slower

An issue of the Spatial Resources e-newsletter points out how important the aerial platform is to the data details. Helicopters are the platform of choice for most transmission line applications.

Spatial Resources reports, “Aerial LiDAR providers are flying at lower altitudes and slower speeds to provide higher point densities.”

The 3-D DEMs/DTMs are of such high-quality detail that many utilities are using them to develop as-built drawings.

Several years ago, Manitoba Hydro needed to upgrade a portion of its 115-kV system. The system was built between 1914 and 1931, so the plan and profile drawings were either severely outdated or non-existent. To upgrade facilities, the utility needed the latest information about the actual condition of the system. It chose to do a LiDAR survey of the terrain and the transmission line, including structure and conductor details.

Manitoba Hydro's Worldwide Integrated Rating Enhancement (W.I.R.E.) Services division performed the survey and provided detailed 3-D models of the existing transmission line and terrain. These were used to supply detailed drawings of the 115-kV transmission lines in question. The LiDAR survey allowed Manitoba Hydro to define problems on the transmission line and upgrade its facilities in a very cost-effective manner.

With all the transmission talk about as-built surveying, it was not long until some enterprising substation engineer asked, “What about substations?” If LiDAR surveying could provide detailed plan and profile drawings of transmission lines, why not have it produce detailed substation drawings? Like transmission lines, substations can be missing documents, too.

Having accurate drawings of substations and switching stations becomes critical as new stations are added and existing stations are upgraded. Existing drawings might only be a record of how the station was designed and not how it was actually constructed. The engineer needs to verify not only how the facilities were built, but also what has been changed over the ensuing years. If the drawings are used as a base for future additions and upgrades, there is always the likelihood inaccuracies will be transferred forward to the new design unless field verification takes place.

Field Data

Prior to the development of laser scanning for the verification of existing facilities, utilities were forced to use personnel in the field. It was a labor-intensive process, and the results were always subject to challenges. The typical approach was to send an engineer with a large surveying crew out to the substation to inventory everything in the station. They took measurements, did sketching and snapped photographs. This approach also may have required outages to take safe measurements around energized equipment.

The length of time required for this task was proportional to the size of the station. Field data was returned to the office and used to produce new detailed drawings of the station. The process was slow and might have been repeated several times because of missing or questionable data. It was not unusual for the process to take months to complete, and its accuracy was dependent on many variables.

In situations such as this, aerial laser scanning systems are quick and provide accurate details. Because of the level of detail and physical arrangement of the station, the aerial platform is best suited to hovering over the substation for an extended period of time. This is not an efficient use of a helicopter and impossible for a fixed-wing aircraft.

In addition, many substations are located in populated areas and the noise produced by a helicopter would be objectionable. There are also related safety issues for aerial laser scanning systems at short distances, since they use both high-intensity visible and invisible light sources. This type of equipment could represent an eye hazard to people in or around a substation if proper safety precautions are not taken.

Grounded LiDAR

This has led to the development of ground-level laser scanning systems from manufacturers like Leica Geosystems, Zoller+Fröhlich, Optech and Riegl. The systems are similar to aerial LiDAR systems, except the laser source can be mounted on a tripod, making them very portable. These systems offer significantly reduced visual risks, and measure the structures and equipment to millimeter precision.

Portability means they are convenient to use, too. They produce phenomenal results in accurate, detailed 3-D spatial substation representations. Another advantage is the fact the data is acquired without any physical contact, which is a big plus in an energized substation. Laser surveying technology provides a whole new perspective for asset management. Rapid laser scanning means more comprehensive data can be collected very quickly, which provides utilities with improved information.

Alberto Quinonez, a substation and project engineer III for Tucson Electric Power (TEP), said, “TEP has seen the benefits of using 3-D drawings for its substation construction and uses this format for all of their additions and expansions.”

In 2003, UniSource Energy (parent company of TEP) purchased natural gas and electric distribution systems previously owned by Citizens Communication Company. Recently, TEP decided to upgrade one of the substations acquired in Lake Havasu City, Arizona.

“The drawings for this old substation were incomplete and obsolete,” said Quinonez. “TEP engineers decided this was a good trial project for laser scanning. After seeing the results, we decided to do laser scanning at the Tucson substation, too.”

The Tucson substation's upgrade consisted of the removal and replacement of outdated equipment and steel structures with gas-insulated switchgear (GIS) technology.

TEP was also sensitive to the public relations aspects of the project. It was important for TEP to be able to show the community what the substation would look like after the upgrades. The new facilities would be a more visually pleasing low-profile design using GIS equipment. Having accurate, detailed 3-D models of the old station to compare with photogrammetric visualizations of the new station would gain public support during the permitting process.

TEP hired Darling Environmental and Surveying Ltd. to perform laser scanning of the both substations. It developed DEMs and provided detailed 3-D station drawings in AutoCAD format. With the proper setting of cutting planes, Darling generated up-to-date as-built plan and elevation drawings.

“We sent a four-person scanning-surveying crew to the 63,000-sq-ft Tucson substation to scan, map and photograph the facility. It took them approximately five hours to perform the field work,” said Ryan Darling, 3-D laser scanning manager of Darling Environmental and Surveying Ltd. “They established control points or targets, which are used to confirm scan data accuracy and assure the scan data is properly aligned. Numerous point clouds were recorded and tied together using the control points.”

Once the field was completed, the data was processed. It took three weeks to develop the 3-D digital models and a complete set of 3-D AutoCAD drawings of the substation. This was all done without using an aerial platform.

“Laser scanners can capture detail that conventional survey equipment could never acquire,” said Darling.

Bubble Viewers

Viewing laser scanning data has always been tricky for non-experts, which discouraged the acceptance of LiDAR beyond the engineering department. But that is changing as software advancements are adopted. It is now possible for anyone to take a virtual walk around a substation or transmission line right-of-way. It can be done by viewing the point cloud with “bubble viewing” software, such as Leica's TruView panoramic point cloud viewer.

Bubble viewing software has been available for years, but usually as a built-in application to specialized 3-D laser scanning software. It has become very user-friendly and is now offered commercially as stand-alone software. Those who have ever used a virtual room tour on a hotel Web site have used a bubble viewer. It is not hard to use and does not require special training.

Bubble viewers allow the user to see a continuous panoramic image of the point cloud. It gives the viewer an intuitive feel, allowing the user to zoom and pan within the point cloud. This technology lets the user walk around the substation. It is even possible to take measurements, see the equipment and identify problem areas. Bubble viewing software images are not meant to replace survey drawings, but they are good enough to allow the user to conduct rough planning and initial design work. They also open this technology to the non-expert, which is a huge benefit in advancing the use of LiDAR technology.

Laser scanning technologies, coupled with sophisticated software are changing the way transmission facilities are designed and maintained. Digital models of substations can be linked to manufacturers' Web sites and equipment drawings in the utility's files, making them available to everyone with access to the models. Digital files, such as high-definition photographs of station equipment, also can be linked to the virtual substation model. This technology saves site visits (windshield time) and provides the user with an encyclopedia of the substation.

Utilities trying to get more bang for their buck should seriously consider the LiDAR advantage.

Companies mentioned in this article:

Autodesk, www.usa.autodesk.com

Darling Environmental and Surveying Ltd., www.darlingltd.com

EPRI, www.epri.com

ESRI, www.esri.com

Leica Geosystems, www.leica-geosystems.com

Manitoba Hydro, www.hydro.mb.ca

Optech Inc., www.optech.ca

Pondera Engineers, www.ponderaengineers.com

Power Line Systems, www.powline.com

Riegl, www.riegl.com

Spatial Resources LLC, www.spatialresources.com

Tucson Electric Power, www.tucsonelectric.com

UniSource Energy, www.uns.com

W.I.R.E. Services, www.wireservices.ca

Zoller+Fröhlich, www.zf-laser.com