A Middle Ground in Laser Technology
Laser Technology Inc. (LTI; Centennial, Colorado, U.S.) is finding that lasers and vegetation management do mix — especially when addressing the inevitable topic of system reliability. Traditional surveying requires multiple men on the ground and the use of complicated, fragile equipment. Although the instruments themselves are highly accurate, the method that surveyors must implement for this task is not.
Where is the benefit? Quick setup time is a huge benefit of using LTI's laser system. Because the laser can be used hand-held and an optional BlueTooth adapter can be added, users can simply walk up underneath the line and obtain a clearance value in a matter of seconds.
Helicopter surveying typically calls for expensive flight hours and sophisticated data management. As a result, there is a long delay in receiving information, which has to be “ground-truthed” by workers anyway to verify accuracy. LTI provides simple-to-operate, rugged instrumentation that a single employee can use to get instantaneous field results.
With LTI's laser, utilities can find the height of a tree to plus or minus 6 inches. Using a special software package, utilities can spot the location of a distribution or transmission span and take into account the catenaries of a line. By using the laser to locate the base of a tree, the software can calculate the clearance if the tree were to fall in a direction perpendicular to the line. A field operator can then determine how much clearance cushion is available and, thus, whether the action needed is in years, months or days. The software also allows users to choose between two conductor clearance routines. If the area directly below the conductor is inaccessible or just too difficult to occupy, users could position themselves at the tree in question and still obtain the same results.
Optimal Geomatics Delivers Effective UVM Program
Optimal Geomatics (Vancouver, British Columbia, Canada) and PDG Helicopters (Inverness, United Kingdom) have developed an innovative strategy for the inspection of entire overhead-line networks. Consistent data relating to approximately 2000 km of power lines and their associated assets can be collected per month, allowing large networks to be inspected in relatively short time periods. This has been achieved by using helicopter-mounted aerial sensors in conjunction with ground-based inspection protocols.
Data is captured, processed, analyzed and returned to Optimal Geomatics and PDG Helicopters clients in an appropriate database format. The information submitted is then used to assist in:
Developing risk management tree-cutting strategies on an affected span basis, delivering both network safety and resilience clearances
Delivering comprehensive asset information into asset management systems to enable effective asset management strategies that will respond to regulatory pressure and rising customer expectations
Designing accurate future capital and operational investment strategies.
The data sets collected and provided using this methodology would allow district network operators to prioritize the future management of tree clearance and other maintenance activities for entire overhead-line networks.
One clear advantage of this inspection and post-processing strategy is the ability to accurately target vegetation clearances effectively based on risk. This encompasses key issues such as distance to conductor, environment, and circuit or line sensitivity. Using this data, tree cutting is targeted to high-risk locations, thereby addressing immediate requirements. Planned maintenance and effective management can then be executed in a credible, visible and economical manner.
WIRE Services Utilizes Aerial LiDAR Technology
As a service provider of thermal rating and vegetation analysis, WIRE Services (Winniped, Manitoba, Canada), a division of Manitoba Hydro, is seeing an increase in requests and inquiries for vegetation encroachment studies.
Through an exclusive arrangement with data provider LiDAR Services International, WIRE Services has been utilizing aerial LiDAR technology for over five years to conduct thermal rating and vegetation analysis for utilities across Canada and the United States.
The benefits of using LiDAR technology are its speed, impressive accuracy and the multitude of uses that can result from the data. For instance, as the laser pulses from the airborne helicopter, the light is reflected off of any object below the sensor. In a typical flight the sensor logs more than 400,000 object hits in a single mile. These hits, or LiDAR points, each have an x, y, z coordinate that locates the object, which can be anything from wire to structures to leaves on a tree, all with an accuracy of 4 inches to 6 inches (10 cm to 15 cm).
Using the LiDAR data, WIRE Services is able to model the existing transmission line to analyze the effects of high temperature sags and even extreme wind and ice loadings. They are also able to isolate all laser hits from vegetation and conduct an analysis between the wire at high temperature sag and the closest vegetation points.
Another proponent of airborne LiDAR technology is Public Service Electric & Gas (PSE&G; Newark, New Jersey, U.S.). WIRE Services recently conducted a LiDAR survey on a number of PSE&G's lines and is delivering computer models and a complete thermal and vegetation analysis.
As mentioned earlier, there is a multitude of uses that can result from the use of LiDAR data. Manitoba Hydro has been using LiDAR for thermal ratings for quite some time and is now using vegetation data to analyze proximity to wire and growth along the rights of way.