Quantification of wind, snow and ice loading on New Zealand’s transmission line network during high impact weather events
I am born and bred in Tāmaki Makaurau Auckland and earned my Bachelor’s degree in Mechanical Engineering with First Class Honours in 2019. One of my passions is fluids (air, water, etc) so a project which combines both of these felt like destiny came knocking. In addition to all the academic stuff, I also really enjoy music (both playing and listening), to the point where you could say it’s an obsession. On top of this I like to keep fit through the gym and running, and last year I started learning how to sail which I want to continue to do.
My Project
TL;DR
Wind and ice on transmission lines = bad and we must protect them.
Ice loads estimated through numerical ice accretion model coupled with numerical weather prediction modelling.
Quasi-static wind loads evaluated through field and wind tunnel tests.
Research Questions
Ice
- What are the predicted ice loads on transmission lines in New Zealand for different return periods using high-resolution modelling?
Wind
- Does the existing span reduction factor theory used in the design of transmission lines for homogeneous terrain differ when applied to complex terrain?
- Under what conditions does the resonant component of the fluctuating response need to be considered in the overall response?
The effects of wind and ice loading on transmission lines can result in catastrophic failures. It is easy to imagine how disastrous it would be if a vital link in New Zealand’s transmission network were to fail during an icing event. This project aims to develop improved models of wind, snow and ice loading on transmission lines, to improve the resilience of New Zealand’s electricity infrastructure.
For the snow and ice research, an ice accretion model has been coupled with numerical weather prediction modelling (the New Zealand Convective Scale Model; NZCSM) to estimate the growth of ice on transmission line cables across New Zealand. These predictions will be used to conduct extreme value analysis to inform the design ice loads for transmission lines across the country under different return periods. For the wind research, the quasi-static wind loading of transmission lines will be evaluated and expanded for complex terrain. Observational field tests will be conducted on instrumented full-scale transmission lines to measure the wind climate and associated loads on both flat, homogeneous terrain and complex terrain. The resonant component of the quasi-static response will also be evaluated through full-scale monitoring. This will allow us to establish a complete picture of the associated loads mainly at lower wind speeds where the displacement of the transmission lines is important.
Further field tests will be conducted in alpine regions to validate the ice accretion modelling, as well as wind tunnel investigations of wind flow over complex terrain, such as mountainous regions. The results of these investigations will be used to improve the understanding of wind, snow and ice loads on transmission lines which will improve the resilience of New Zealand’s electrical infrastructure and influence future design procedures.
Next Steps
Now I’m about a year and a half into my PhD programme so things are starting to move forward. After some COVID-related delays, I’m hoping to start my field work in 2022 (crosses fingers) with results starting to flow in quickly after that.
