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  • Managing the UK's electricity system

  • Control CentreAt National Grid, we’re responsible for managing the flow of electricity to homes and businesses across Great Britain.

    We own the high-voltage electricity network in England and Wales, and operate this system right across Britain (Scotland’s high-voltage network is owned by Scottish Power and Scottish Hydro).

    What are we responsible for?

    We’re the system operator, so it’s down to us to manage the flows, security and quality of electricity to Britain’s homes and businesses.

    We do this on a real-time basis: our job is to balance the network, ensuring that supply and demand are perfectly matched from one second to the next. So when demand rises, we call on suppliers and generators to make up the difference.

    We are not responsible for building power stations or for ensuring there’s enough electricity to meet demand – that function is fulfilled by the energy market and its supporting policies and framework.

    What if there’s a shortfall?

    If a power station develops a fault and can’t generate electricity, or if there’s an unexpected spike in consumer demand, we use one of the following tools to communicate shortfalls to the market:

    • Electricity Margin Notice (EMN) – this is a formal communication that lets market players know that our usual ‘safety cushion’ is not as big as we’d like it to be at a particular time of that day. Previously known as a NISM but changed from 30 Sept 2016 to improve clarity.
    • High risk of demand reduction (HRDR) – we use this when we don’t have much time to notify the market of a sudden shortfall
    • Demand control imminent (DCI) – if the market doesn’t respond to the HRDR, we can issue a DCI notice asking the electricity distribution companies to reduce demand across their networks. Often a slight reduction in electricity voltage will do the trick – consumers may notice their lights dimming. But if there’s a very severe supply disruption, the distribution companies may need to implement controlled power cuts to homes and businesses.

    How efficient is our network?

    Managing an electricity transmission network that services the whole of the UK is a mammoth task and a huge responsibility. We take our role very seriously and seek to operate our network as safely, efficiently and smoothly as possible at all times.

    The network is 99.9999% reliable – a statistic we’re proud of.