Behaviour of Cable Systems under Large Disturbances

Scope

The Scope of Work documents the resultant damage, required repairs, recommend improved accessory and cable designs, and suggests alternate installation methods for LV, MV, HV and EHV cable systems due to the occurrence of major disturbances.

Major disturbances include the following events:

• Floods, fire, droughts, and global warming,
• Major earthquakes, liquefaction, resultant landslides, lava flows, and tsunamis,
• Hurricanes, cyclones, typhoons, tornadoes
• Ice storms, avalanches, windstorms, and mud and/or landslides.

War, terrorism, and sabotage are not included within the scope of this technical brochure along with electromagnetic pulse activity due to sun eruptions, solar flares, etc.

Climate Change

The earth’s climate has changed throughout history. Just in the last 650,000 years, seven cycles of glacial advance and retreat have occurred. The abrupt end of the last ice age about 7,000 years ago, marked the beginning of the modern climate era – and of human civilization. Most of these climate changes are attributed to very small variations in the Earth’s orbit that change the amount of solar energy our planet receives. The current warming trend is of particular significance because most of it is very likely human induced and is proceeding at a rate that is unprecedented in the past 1,300 years. [1]

Over the past few decades, changes in weather patterns due to climate change or global warming have led to more extreme, frequent, and costly weather events that have included intense rains, ice storms, tornadoes, floods, hurricanes, heat waves, droughts, and wildfires. These events have caused hundreds of major power outages which have forced schools to close, businesses to shut down and impeded emergency services, thus raising the economic costs to hundreds of billions of dollars. To combat the growing problem, many utilities are developing strategies to modernize and 'harden' their electric grid.

New initiatives are directing substantial investment to improve grid efficiency, capacity, reliability, and resiliency. These efforts will not only help make power grids less vulnerable to weather-related outages but will also help reduce the time it takes to restore power after an outage occurs. [2]

 

Summary of Recent Large Disturbances

According to the United Nations Office for Disaster Risk Reductions, there has been a rise in climate-related disasters during the past 20 years. Between 1980 and 1999, there were 3,656 climate-related events, as opposed to 6,681 between 2000 and 2019. Those differences are reflected in the number of floods, which have more than doubled in the past 20 years, while the incidence of storms increased from around 1,457 to around 2,034.

The deadliest events recorded in 2019 were the summer heat waves that affected Europe, more specifically France, Belgium, and the Netherlands, with over 2,500 deaths. The National Oceanic and Atmospheric Administration (NOAA) ranked 2019 as the second warmest year on record.

Temperature records were also shattered on individual country levels: for the first time, Belgium and the Netherlands recorded temperatures over 40°C. In general, the impact of heat waves remains grossly underestimated. This is primarily due to underreporting in developing countries, where temperatures often exceed European values by a large margin and local populations have limited possibilities to protect themselves from heat wave exposure.

The deadliest event consisted of the flood in North India due to the high monsoon rains, which affected 13 states and caused nearly 2000 deaths was deadliest disturbance of 2019: it lasted from July to October. Two storms were the next most deadly events: Cyclone Ida which affected central Mozambique and Zimbabwe (March) with over 1200 deaths/missing;...