Terrestrial LiDAR

If a picture is worth a thousand words, what is a pixel worth to a substation? Electrical substations are everywhere — generation substations, transmission substations, distribution substations, privately owned substations and the list goes on. Not as obvious is the fact that a very large percentage of them were built 50 to 70 years ago, which brings up an interesting dilemma: At some point in time, it is a good bet that these substations will be expanded or refurbished.

Although they may have outlived their design life, these substations are still necessary. This is especially true considering all the new substations utilities need to add to their fleet. Several polling groups have estimated the cost of revitalizing older substations and adding new ones to be more than $1 trillion in the United States alone. That is a lot of engineering hours and construction time, in addition to money required for materials. How can resource-strapped utilities do it all?

Technology Can Help

Utilities need to take advantage of modern technologies. Light detection and ranging (LiDAR) technology is a good example. Once considered a niche market item, it has become a major player in many industries. LiDAR continues to evolve and mature as new hardware and software are introduced. These improvements are responsible for many new applications, which, in turn, have led to innovative approaches for old problems.

One advancement that has generated excitement in many engineering disciplines is terrestrial LiDAR. This variation has found wide acceptance in the engineering, mining and industrial markets. It has been embraced by refineries, airports and manufacturing plants where it provides detailed 3-D models used in retrofitting projects and mobile mapping schemes. These ground-based LiDAR systems supply accurate 3-D images similar to those provided by aerial LiDAR systems, but they offer the ability to capture 3-D geometrical images previously not available.

Ground-based LiDAR offers what the experts call “platforms of opportunity” (for example, cars, trucks, boat, tripods, trains) that can provide something totally unique — a street perspective. The keywords here are “street perspective.” Being able to capture elevation information as well as asset details in a 360-degree field from ground level is creating interest from many different users.

Terrestrial laser scanning is being used for one application that should be of interest in substation engineering departments. In its simplest form, LiDAR can supply a comprehensive set of as-built drawings that are a snapshot of exactly what is installed in the substation. In its more complex form, it is a highly detailed 3-D model of the substation that can serve as a virtual substation on the engineer's computer.

Terrestrial LiDAR can help answer a perplexing problem that has always plagued substation engineers. They may know how the substation was designed, but do they know what was actually built? Did the construction manager submit accurate as-built documentation that captured all the field changes? Were the file drawings updated?

An Untapped Market

With terrestrial LiDAR, utilities have a solution that comes at a very opportune time. Substations that are candidates for expansion or refurbishment will consume engineering department resources as never before. This LiDAR advancement offers the advantages of speed, and it collects assets and features with a high degree of accuracy.

“Terrestrial LiDAR is not well known in substation applications, but it is almost like the technology was created with the substation engineer in mind,” says Vernen Lee, project manager, Merrick & Co. “There is no situation where its benefits will be felt as dramatically as in substation expansions. It has revolutionized the role of surveying in many industries, but it needs to get its foot in the door for substation survey data.”

Point of View

Aerial LiDAR has been such a valuable tool for transmission line design and vegetation management. Now, terrestrial LiDAR is available, but it has not generated much interest in substation design work. It could be that the term LiDAR is associated too closely with transmission applications. That success may be partially responsible for the lack of enthusiasm in using ground-based LiDAR in substations. Stereotypes can be hard to change, and substation engineers may be overlooking an important tool that is right in front of them.

There also is the perception this technology is complicated and requires a lot of time learning how to use it. That may have been true in the early days, but LiDAR software has become more user-friendly with each new release. Manufacturers realize the perception that LiDAR data is hard to synthesize and apply, and are working to address misconceptions. The manufacturers have developed several smart LiDAR viewers, which are available free on the Internet.

One of the most popular LiDAR viewers is Leica TruView and Cyclone PUBLISHER software. This software was developed to permit anyone with computer skills to work with LiDAR data without having to be an expert in laser scanning. The user can move around the model, extract 3-D coordinates, make accurate measurements and add notes in the form of markups.

Adding Depth to Designs

Another challenge is the fact a typical substation construction drawing has not changed much since the days of ink and parchment. They are 2-D representations on the flat surface of paper. The drawing packages are simple to read but lack information. For example, a 2-D drawing cannot supply useful clearance information.

Going from 2-D drawings to 3-D design is a quantum leap, and a leap relatively few have taken. This is surprising since 3-D capability has been part of utility computer-aided design (CAD) programs since the 1990s. There are even third-party plug-ins available today for programs like AutoCAD that allow an engineer to design substations in 3-D without extensive 3-D training or practice.

Designing in 3-D tends to be overwhelming at first. Add LiDAR models to the mix and it can be really intimidating, but for those who have made the effort, the rewards are fantastic. One LiDAR provider reported that users who have made the transition to 3-D design work tend to be more accepting of LiDAR technology. They quickly understand LiDAR's digital elevation models (DEMs) and digital terrain models (DTMs) and how to apply them to their workflow.

This is why transportation agencies, manufacturing plants, civil engineering companies and many others are much farther along the terrestrial laser scanning learning curve. They made the changeover to 3-D drawings for design work some time ago. State department of transportation agencies would be lost without having adopted the technology a long time ago for these exact reasons.

Where LiDAR Shines

For complex small-footprint facilities such as substations, the laser device is placed on a tripod in the substation. The data-gathering process is pretty simple. A GPS receiver station is set up for precise positioning information and a tripod-mounted target is used as a reference point as the scanner moves.

The operator enters the scanning parameters, pushes the scan button and from there, it is pretty automatic. The scan records everything around it in a half sphere with the scanner at the sphere's center. It produces a very localized data cloud by recording millions of measurement points within its range — typically a couple of hundred feet depending on the equipment used. The LiDAR points are accurate to millimeters, and each of these points is referenced to x, y and z coordinates relative to all the other points in the cloud.

After a few minutes, the scan is completed, and the scanner is moved to the next location. Each spherical location overlaps the previous one by a predetermined amount. This process is repeated until everything in the station is accounted for in a series of data clouds. Once the site work has been completed, it is time to take the data back to the office where the real work begins.

The raw data is loaded into a computer and processed with LiDAR data-crunching software. It is stitched together, georeferenced and manipulated until the 3-D model of the facility is generated. A software application is used to produce the deliverables. Users can choose from a variety of results, including detailed 3-D substation drawings that are scalable, contour maps and animations. All of the major CAD platforms have been modified to include LiDAR viewer capabilities.

Having the capability to visit a substation with just the click of a mouse is mind-boggling. So much information is needed before the actual design takes place, and it is available at the engineer's fingertips in the 3-D DEM. Whatever the engineer wants to verify is only a mouse click away. The old and new buses are no longer at risk of being off a couple of inches, and even more important, there is no danger of a new bus and an existing transmission line flashing over because of a lack of clearance between them. Physical dimensions cannot be trivialized and being able to verify any dimension of anything and everything in the station from a computer screen is a huge advancement.

With terrestrial LiDAR, the designer, for the first time, has a precision model of the actual station, including everything from lattice steel to overhead transmission lines. These lines can be a geometrical nightmare when it comes to clearances. There are literally hundreds of variations of elevations that change constantly with temperature, electrical loadings and wind conditions. Using DEMs and DETs, clearance issues can be seen and measured, and solutions defined before actual construction takes place, reducing costly field modifications.

Innovations Within Innovations

The imagery produced by terrestrial LiDAR is staggering in its clarity. It is getting better with each advancement and upgrade to the technology, but it is not the quality of a photograph. And people relate to photographs, having been exposed to them their entire lives, which is why several LiDAR providers have combined photogrammetric technology with LiDAR.

Merrick & Co. has an interesting approach — a panoramic visual database. The LiDAR technician takes a series of traditional visual wavelength panoramic photographs using a high-resolution camera and a fisheye lens at each laser scan position when he or she maps a substation. The photos are viewable using a freeware panorama viewer. The viewer makes it possible to combine the panoramic photos into a 360-degree view of the substation from that point. The user controls the view movement with the mouse.

Merrick & Co.'s Lee says, “Engineers can visit the substation without leaving the office. They can click on any of the camera icons located throughout the model. This allows the viewer to see an actual photographic view of what the LiDAR representation looks like at this point. The photo acts like a reference point for those unfamiliar with the LiDAR environment, permitting them to see what is going on.”

Safety Benefits, Too

There is another benefit to terrestrial LiDAR that is a major advantage for the utilities using it. LiDAR removes all the safety issues concerning the technicians measuring and surveying in the substation. The LiDAR data collection system does not require any object in the station to be physically touched to be measured or mapped. One of the worst-case safety scenarios for a utility's safety department is a group of people in an energized substation.

It gets worse when they are moving among the energized equipment and bus work with poles, rods and other manner of long, unwieldy measuring devices. Safety experts know that one moment of inattention can spell tragedy. For example, a technician measuring the height of a transmission line conductor with a fully extended fiberglass hot stick is the definition of a precarious situation.

Seeing the Substation in a New Way

Terrestrial LiDAR is a technological variation proven to be fast, efficient and cost-effective for those utilities that have used it. It gives the designer and engineer a substation in 3-D that can be manipulated by using various software applications. This lets them see details and features within the substation with a clarity undreamed of prior to the development of this technology.

Adam Rousselle, president and CEO of Utility Risk Management Corp., says, “Component mapping within the substation with terrestrial LiDAR may help to determine quickly if the as-built drawings match the components.” However, Rousselle also points out, “Remote sensing value will be seen in the coming year as sensors are tuned to detect leading indicators of maintenance needs, limiting factors and constraints. Mapping is not enough anymore.”

Terrestrial LiDAR is poised to revolutionize today's substation engineer as much as the iPad and e-tablets have been revolutionizing e-paper. Like most advancements, it will be slow at first, but there is no stopping the rising tide of technology.

Companies mentioned:

Leica www.leica-geosystems.com

Merrick & Co. www.merrick.com

Utility Risk Management Corp.www.utilityrisk.com