Helping South African power grid brave thunderstorms

Hitachi ABB Power Grids PEXLINK line surge arresters can safeguard transmission lines from lightning strikes, ensuring ‘business as usual’ for everyone in the country

Zurich, 19 January 2021 – South Africa is the leading services destination, regional manufacturing hub and the most industrialised country in Africa.[1] This makes it imperative to be supported by access to reliable power. To maintain availability and reliability of power supply across the country’s power network of more than 31 000 km [2] requires consistent efforts by utilities and the use of innovative solutions. Climate and geography can pose crucial challenges in such situations.

Experts predict an increase in the number and severity of thunderstorms in South Africa due to climate change and global warming.[3] Also, the landscape of South Africa is dotted with mountains and high plateaus. Transmission line towers installed in such terrain and height have higher chances of being struck by lightning, causing failure of critical equipment in the power network and leading to a blackout. Experts predict an increase in the number and severity of thunderstorms in South Africa due to climate change and global warming.[3]

To protect South Africa’s power network from such risks, an innovative solution can now be applied – Hitachi ABB Power Grids line surge arrester (LSA) PEXLINK.

Surge arresters are the primary protection device for critical equipment in the electrical network from over-voltages caused by switching operations or natural atmospheric events. They protect the equipment from serious damage that can lead to costly downtime, expensive equipment failure and 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 improve the outage rate of the transmission line by installing LSAs on selected towers along the transmission line. 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 flashover, part of the lightning current in the affected tower is shunted through the LSA(s). The LSAs in the towers in the immediate vicinity then act as the next layers of protection, shunting the current from the phase to the ground. These multiple layers of protection enable a constant, uninterrupted 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 the conservation of the ecology and biodiversity.

The possibility to monitor surge arresters makes predictive maintenance of surge arresters possible, 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 unique monitoring system that provides the utility with safe and effective monitoring of LSAs using remote reading for maximum personnel safety.

With these solutions, South Africa’s transmission system is made more robust against lightning-induced blackouts, thereby enabling a constant reliable supply of power to consumers from bulk and distributed renewable energy sources, enabling consumers across the region to benefit from sustainable energy.