Electricity + Control March 2021

TRANSFORMERS, SUBSTATIONS + CABLES : PRODUCTS + SERVICES

Helping the SA power grid through thunderstorms

Hitachi ABB Power Grids PEXLINK line surge arresters can safeguard transmission lines from lightning strikes, supporting power supply continuity for the country. South Africa is reportedly the leading services desti- nation, regional manufacturing hub and the most indus- trialised country in Africa [1] . This makes it essential for industry and the economy generally to be supported by access to reliable power. To maintain availability and re- liability of power supply across the country’s power net- work of more than 31 000 km [2] requires consistent effort by utilities and the use of innovative solutions. Climate and geography can pose significant challenges. Experts predict an increase in the number and severi- ty of thunderstorms in South Africa due to climate change and global warming. And the South African landscape includes mountains and high plateaus. Transmission line towers installed in such terrain and at such heights have higher chances of being struck by lightning, which can cause failure of critical equipment in the power network and lead to power outages. Hitachi ABB Power Grids’ line surge arrester (LSA) PEXLINK, is an innovative solution that can be applied to protect South Africa’s power network from such risks. Surge arresters are the primary protection device used to protect critical equipment in the electrical net- work from over-voltages caused by switching opera- tions or natural atmospheric events. They protect the equipment from serious damage that can lead to cost- ly downtime and expensive equipment failure and can potentially harm personnel. For utilities, this translates into protection of key equipment like transformers and improved transmission line availability. The advantage of the PEXLINK solution to the utility is to reduce the outage rate of transmission lines by in- stalling LSAs on selected towers along the transmission lines. The selection of towers for installation of the LSAs is done through simulation studies to achieve optimal performance of the line LSAs. In case of a back flash-

over, part of the lightning current in the affected tower is shunted through the LSA(s). The LSAs in the towers in the immedi- ate vicinity then act as the next layers of protection, shunting the current from the phase to the ground.

PEXLINK line surge arresters safeguard power transmission lines against lightning strikes.

These multiple layers of protection enable a constant, un- interrupted power supply from the utility to the consumer. PEXLINK also eliminates the need for investment in additional infrastructure to increase the reliability of the grid, like installation of redundant transmission lines. In South Africa, this means conserving costs, as well as the conservation of ecology and biodiversity. The capability of monitoring surge arresters supports predictive maintenance of the arresters, as well as analysis of transmission line events. Hitachi ABB Power Grids EXCOUNT-II includes these monitoring features while ensuring safe operation of the grid. The EXCOUNT‑II is a monitoring system that provides the utility with safe and effective monitoring of LSAs using remote reading to allow maximum personnel safety. With these solutions, South Africa’s transmission sys- tem can be made more robust against lightning-induced outages, and a constant reliable supply of power to consumers from bulk and distributed renewable energy sources, can be enabled.

References [1] http://www.investsa.gov.za/ [2] https://www.globaltransmission.info/archive.php?id=26672

For more information contact Hitachi ABB Power Grids. Tel: +27 (0)10 202 5841 Email: thembisile.dzonzi@hitachi-powergrids.com Visit: www.hitachiabb-powergrids.com

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