Russians create 3D power map

By RICHARD WOOD

Transpower is one year into a long-term project to survey its power lines nationwide and turn the results into a three-dimensional computer model.

A Russian company is using a laser system that measures the location of the lines in three dimensions from a helicopter.

The system monitors the reflection off the wire at 50,000 times a second and combines that data with information from a highly sensitive gyro stabilisation and satellite positioning package in the helicopter.

The result, once processed in Russia, is a computer-aided design file modelling the power lines in 3D.

Transpower uses the information to identify the height of wires above ground. The more power sent down a line, the more it heats and sags.

But there is a maximum limit a line is allowed to sag for public safety reasons.

Transpower's general manager, service delivery, Kieran Devine, said the company used sensing equipment to measure wind speed, air temperature, solar radiation at its substations and other sites as required.

"Out of that we do a calculation which tells us what the maximum sag on the line will be and that tells us either the capacity we've got left in it or that we are over capacity," he said.

"As we get more experienced, we may put measuring gear at specific sites midway on the line.

"If we have a particularly tight line with a known constriction, we can put the measuring gear right at the point and therefore run it a bit closer to the limit."

The whole project could take three or four years to complete as the company works through the network.

The first benefit is that Transpower will be able to identify where it is cost-effective to make physical changes such as tightening lines to lift them higher.

The ultimate goal is a "variable line rating" system, whereby the rated capacity that each line can handle can be adjusted frequently depending on environmental factors.

At present, lines simply have a summer and winter rating. Some critical lines could ultimately have a rating that changes every 10 minutes, maximising their throughput when required.

This system will use high-tech, point-to-point radio systems which are being produced by Wellington firm 4RF.