flooding resilience of electricity sub stations

8/8/2019 Flooding Resilience of Electricity Sub Stations

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A PRESENTATION BY THE OF ENGINEERING DIRECTORATE THE ENERGY NETWORKS ASSOCIATION

Types of Electricity Substation

400kV Grid SubstationOperated by National GridTransition from National Grid toDistribution Company

132kV Grid Substation

Generally operated by

Distribution Company


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Primary Substation

Operated by



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Distribution Substation

Operated by



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132kV Grid Substationshowing main power conductors at high

level but controlcircuits located incubicles at lower level


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Typical Cubicle in GridSubstation showingcontrol wiring

potentially susceptibleto flooding


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A combination of widespread flooding and extensive power outagespresents communities and those responding to the emergency with

particularly difficult problems.

Power outages can extend well beyond the flooded area affecting vitalservices and the general infrastructure that supports a modern society.

It is important to consider these societal costs when considering

investment decisions and not just the flooding contribution to Customer Minutes Lost shown below


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Flood Risk Information

Location Organisation FloodWarnings

Flood PlainMapping

Flood DepthMapping

Type of FloodingCovered

England andWales

EA Yes (Includingtelephonewarnings)

Yes Yes via EA AreaOffices but limitedcoverage

Fluvial and Sea

Scotland SEPA Yes Yes No Fluvial and Sea

At present only fluvial flooding from rivers and sea flooding is covered because this isthe only data for which EA and SEPA have a responsibility.The report identifies the flood risk information that is currently available andrecommends a standard set of data for collation by Network Owners to identify floodrisk at each substation. It is essential that accurate flood depth information is availableto allow Network Owners to carry out satisfactory assessments.

At present there are no warning systems in place for surface water flooding. Theresponsibility for this is being considered in more detail under Defras review: InlandOverview of Flood Risk Management. In the meantime, the Met Office, and EA aretrialling the Extreme Rainfall Alert system and all Network Companies are receiving theinformation.


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Systematic Approach to Flood

Risk Assessment and ProtectionThe Task Group has identified a number of steps in a systematic approach to

ensure the resilience of electricity supplies against flood risk. This approachcan be summarised as follows:-

a)Identify all substations (within scope) in the flood plain using best availablecurrent data.

b)Establish the flood risk assessment for each substation to identify predictedflood depth and other key factors to establish which substations are at risk i.e.where the predicted depth of flooding is likely to cause damage to key parts of the substation resulting in the loss of supplies to customers.

c)For each substation that is at risk of flooding, identify the flood impact for thatparticular site including societal impact.


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Systematic Approach to Flood

Risk Assessment and ProtectionEstablish if the site is or will be protected by a flood protection scheme sponsored

by the appropriate public authority.

If the site is to remain unprotected by public authority, establish the mostappropriate protection solutions and the cost of protection works for eachsubstation. In establishing the most appropriate protection solutions,companies will consider their individual approaches to managing flooding riske.g.

Moving the siteProvision of permanent or temporary barriers

Protecting all the site or only key areas.


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Levels of flood risk to be considered

and implications for investmentThe Report recommends that for the purpose of developing initial proposals for

improving resilience the following levels of risk should be considered, however the actual level of resilience will depend on a detailed assessment of the costsand benefits for each site and the regulatory investment framework agreed with

Ofgem.

a) For Grid/Bulk Supply Point and Supergrid sites, which typically cover between50,000 and 400,000 customers, subject to cost/benefit assessment electricitysupplies should be resilient to the level of flooding that would occur within a1:1000 year flood contour. Where the cost benefit does not support thisapproach, then as a minimum electricity supplies should be resilient to floodingthat may occur within a 1:100 year flood contour (or 1 in 200 for sea flooding)without reliance on temporary flood protection methods.


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Raising bundheight, to critical

plant and accesssteps .


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Raising bundingto critical plant

using metalpanelling .


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Exterior of buildingflood protection.

Access to Substation.

flooding resilience of electricity sub stations

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