Coping with nature's whims

IEC work helps mitigate consequences of natural phenomena

By Morand fachot

Electrical installations and supply can be directly and adversely affected by natural phenomena and disasters such as solar storms, hurricanes, extreme cold or heat, bad weather conditions, lightning, etc. A number of IEC TCs (Technical Committees) prepare International Standards to ensure systems are properly built to operate in extreme weather conditions – and, if required, to mitigate or prevent the severity of their impact – and can be repaired rapidly and efficiently.

Lightning is dangerous for unprotected electrical installations and buildings

From the Sun

Solar storms are frequent, their effects have been measured since the 1840s using ground-based magnetometers. Records show that there have been many solar storms, but only a very small number of them are severe. The largest was recorded on 2-3 September 1859, the day after a huge solar flare was observed on the surface of the sun. Aurora, normally seen in high latitudes, could be seen as far south as the Caribbean.

Solar storms release huge volumes of charged particles from the surface of the sun. These can create extra electrical currents in Earth's magnetosphere and can infiltrate the electrical power grid and high-voltage transmission lines, causing transformers to overheat and possibly burn out. This happened in March 1989, when a solar storm resulted in grid failure in the Province of Québec, Canada.

A so-called 1-in-100 year solar super-storm would have a devastating effect on many systems such as power grids, communication networks, navigation and electronic equipment.

Experts in IEC TC 77: Electromagnetic compatibility, and its SCs (Subcommittees) have experience in dealing with complex electromagnetic problems and are holding discussions on the possibility of working with other TC committees in IEC and Cigré (Council on Large Electric Systems) to advance the understanding of this complex problem.

From the skies and the seas

Weather conditions can be severe and are allegedly becoming more so and more frequent.

The most striking example of this in recent years was Hurricane Sandy that hit the US Eastern seaboard in late October 2012, after having wreaked devastation in many countries and islands in the Caribbean region. Sandy destroyed transformers, downed overhead power lines and flooded underground cables and other systems. Storm-related power cuts left more than 7,4 million homes and businesses without electricity in and around New York City, and knocked out mass transit transportation along a wide swathe of the eastern US. Damage in the US alone is estimated at over USD 71 billion.

There have been many examples of natural disasters or extreme weather conditions like tsunamis or hurricanes that have provoked serious damage in many parts of the world in recent years.

Prevention is better than cure

Electrotechnical and electronic products intended for general use are expected to work all over the world irrespective of climatic conditions, operational mode, and mechanical environment or handling; as a result, many IEC TCs develop their own climatic and mechanical robustness testing procedures.

IEC TC 104: Environmental conditions, classification and methods of test, standardize environmental tests and provides guidance on the selection and use of these standards. It has a WG (Working Group) that collects data and makes recommendations regarding climatic conditions and climatic methods of tests, and another WG that collects data and makes recommendations regarding dynamic field data. TC 104 provides standards with Horizontal Safety Function for methods for climatic tests and for testing mechanical robustness. It maintains internal liaisons with 7 different IEC TCs and SCs, as well as with ACOS (IEC Advisory Committee on Safety).

Another domain where prevention is better than cure is that of lightning protection, as damage to buildings and other installations can be severe and prove far more costly than installing lightning protection systems. Lightning protection has been around for a very long time and validated by empirical experience.

The role of IEC TC 81: Lightning protection, is to "prepare guides or, where possible, international standards, for lightning protection for structures and buildings as well as for persons, installations and contents in or on them".

Its International Standards cover general principles (design and installations) of lightning protection, physical damage to structures and life hazard, electrical and electronic systems within structures, and risk management. TC 81 also has a WG that prepares standards on LLS (lightning locations systems), to estimate the risk posed by lightning in certain locations.

Tall structures, such as wind turbines, have special requirements as regards lightning protection. IEC TC 88: Wind turbines, has developed IEC 61400-24, its own International Standard for lightning protection.

Extreme weather conditions

Certain environmental conditions, such as exposure to extreme temperatures, can have an impact on particular installations. Some of these are addressed by TC 104. International Standards are intended to be adopted as broadly as possible. However, national variations are needed to leave room for differences in the operating conditions of equipment and systems, such as those encountered in hot or cold countries.

For instance some TC 88 experts from cold climate countries look at specific aspects of particular concern in their part of the world, such as the formation of ice on wind turbine blades, which could cause turbines to fail.

Likewise, wind classes are a central element in wind turbine design and erection, they are meant to prevent the installation of specific types of turbines in locations for which they are not suitable because of prevailing wind conditions (speed and turbulence). However, extreme weather and one-off wind conditions may still result in damage to wind turbines that have been properly selected and installed.

Some measures, such as burying power cables underground, may help prevent power outage in extreme climates or regions prone to severe weather conditions, but can be extremely expensive. Running cables underground has been estimated to cost 10 times as much as the installation of overhead lines.

If the worst comes to the worst

The best standards cannot prevent equipment and installations sustaining serious or total damage in case of extreme or severe natural conditions. Recent examples of this are to be found in downed overhead cables, damaged transformers or substations that require replacing or fixing.

Repairing installations often means technicians and engineers having to work on live installations. IEC TC 78: Live working, prepares "International Standards for tools, equipment and devices for utilization in Live Working", that is "on, and in the vicinity of, live parts of electrical installations and systems". These standards include the performance requirements, care and maintenance of such tools, equipment and devices. (see article on TC 78 here)

Live working is not only used in case of damage to installations, but also to avoid costly and disruptive outages. Repairing equipment also means deploying temporary systems such as mobile transformers; TC 14 prepares International Standards for power transformers.

Repairing and recovering

Recovering from extreme weather events can be a lengthy and costly process that leaves communities and industry without power. A solution has emerged recently in the form of microgrids. Microgrids allow power to be available and distributed to small communities where or close towhere it is generated. A smart factory, a smart building, a smart hospital, a smart store or an intermediate level grid with EES (electrical energy storage) may be treated as a smart microgrid.

With their flexibility in resisting outages caused by disasters smart microgrids are seen as an interesting solution for recovery. Following various disasters and significant damage that has delayed recovery in many countries, the IEC's MSB (Market Strategy Board) introduced a MDR (microgrid for disaster recovery) project in September 2012. The MSB held a Microgrid Disaster Preparedness and Recovery workshop and meeting in early 2013.

Countless other IEC TCs also prepare International Standards for components, systems and installations that are essential to the prevention, mitigation or reparation of adverse effects of extreme natural phenomena. They, together with those mentioned in this overview ensure that whatever the circumstances power, can be maintained or re-established in the shortest possible timeframe .

lightning Lightning is dangerous for unprotected electrical installations and buildings
powerline_02 Snow storms, hurricanes can bring down power lines and pylons
Depositphotos_8134581_original Substations may be damaged by hurricanes, solar storms and other phenomena