Electricity + Control August 2019

ELECTRICAL PROTECTION + SAFETY

Protecting wind power one turbine at a time

Florian Vögerl, Head of Sales and Operations at DEHN Africa, points to the increasing role of wind energy in South Africa’s renewable energy generation matrix and highlights the need for proper earthing and lightning protection of wind turbines.

I n South Africa, most of us think of solar energy when we think of renewable energy sources. The use of photovoltaic power is on the rise and the public is becoming more aware of large scale solar power plants as well as smaller solar installations serving individual businesses and homes to reduce their dependence on the national grid. What about wind as a renewable energy source and where are we in South Africa with this option? Vögerl cites a 2016 study by the Council for Scientific and Industrial Research (CSIR) which noted that the capacity to produce electricity from wind turbines in South Africa was more widely spread than initially thought and was in fact on a par with the country’s solar energy. Since then, wind energy has become an increasingly important part of the renewable energy mix. “At DEHN Africa,” says Vögerl, “we play a critical role in protecting wind turbines used in power generation from the destructive impacts of lightning and power surges.” Renewable energy in South Africa The energy landscape in South Africa is in a state of upheaval, as is reflected in the ongoing uncertainties and delays related to the Department of Energy’s (now the Department of Mineral Resources and Energy) latest draft Integrated Resource Plan for electricity (Draft IRP 2018). The draft IRP walks a tightrope among a number of different stakeholders, including government, labour, business and communities. In the debate on the way forward, there are those who want coal-fired energy generation to continue for as long as possible, largely to support job continuity; a number voting for nuclear; and a growing voice for the green light for renewable energy sources.

Vögerl comments: “When you think that, according to the CSIR, the cost of new wind generation is 40 percent cheaper than that of coal, it makes sense to explore wind energy as a renewable energy option in South Africa. We have vast areas of the country that are very windy, such as the Eastern and Western Cape and parts of the interior. In addition, the average time required for construction to completion of renewable energy projects is only 1.9 years, which allows a new source of energy generation to be connected to the grid relatively quickly. “At DEHN Africa, we are aware that legislative issues still need to be resolved around the implementation and integration of different energy sources into the grid overall. But I think it remains a certainty that more wind turbines will be required in South Africa, and they will need to be protected against lightning strikes and electricity power surges – one turbine at a time.” Protection against lightning strikes Lightning strikes to renewable energy equipment, such as that used on wind or solar farms, or rooftop solar panels, will cause damage at the strike point and surge damage to any equipment that is connected downstream. While external lightning protection helps avoid damage at the strike point itself, surge protection devices help prevent downstream damage caused by conducted and induced surges from the strike, and thus enable the renewable energy system to stay online. In South Africa many areas have a very high lightning ground flash density (a measurement of the number of lightning strikes to the ground over a period of one year). There are, in fact, areas where the country’s ground flash density is comparable

The reinforced concrete foundations of wind turbines should serve as a foundation earth electrode.

1. Wind turbines need to be protected against lightning strikes and electricity power surges. Take Note! 1

30 Electricity + Control

AUGUST 2019