How can utilities maximize 3-D modeling?
Many electrical transmission line owners are studying the feasibility of upgrading their existing infrastructure. They’re also busily assembling up-to-date inventories of lines for geographic information system (GIS) and maintenance programs. Both of these monumental tasks can be completed much more accurately and effectively with digital airborne light detection and ranging (LiDAR) data and orthorectified imagery.
The data and imagery, combined with advanced modeling software, allows complete line verification and analysis. Determining the exact maximum thermal operating limits of a transmission line with respect to minimum ground clearances permits efficient, cost-effective upgrade solutions with minimal social and environmental impact.
3-D Model Applications
The key objectives of LiDAR analysis include precisely determining the thermal rating of transmission lines and identifying encroaching objects to the phase conductors– e.g., overgrown vegetation contained within the limits of the transmission line right of way.
Finite Element Applications. Conductor operating temperatures and weather events, as specified in national and local standards, are checked to the right of way for any detectable encroaching objects and vegetation in each span. A Finite Element (FE) feature for matching individual cables inside the model to actual LiDAR points allows for a comprehensive analysis of the entire line.
Historically, cable sags are derived using ruling span calculations; unfortunately, this doesn’t provide an actual representation of the entire line span for span, phase for phase. Separating and classifying individual LiDAR phase hits of each transmission line dead-end section allows software such as PLS-CADD, a line design package from Power Line Systems, to perform FE calculations that match the catenary shape of the conductor at the time of survey for each span.
This analysis method produces a clearer understanding of the potential problem areas when clearance and thermal rating reports are generated. Instead of de-rating an entire line, utilities can focus on specific spans and/or phases to return a transmission line to its desired operating temperature.
