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UKPN: ANM Connects one of UK's Largest Solar Farms

UKPN: ANM Connects one of UK's Largest Solar Farms

By introducing Smarter Grid Solutions Active Network Management system to an area of our network, we have reduced connection costs for six new distributed generation customers by up to 90%, as well as offering them far shorter connection lead times.

Sotiris Georgiopoulos , Flexible Program Director, UK Power Networks

UK Power Networks (UKPN) and Smarter Grid Solutions have connected the first phase of a 32MW solar farm (Scottow Moor) into an Active Network Management Scheme. As part of the ‘UKPN Flexible Distributed Generation Connections (FDG) - Norwich Zone’, Smarter Grid Solutions designed and delivered an Active Network Management (ANM) solution and provided curtailment assessment studies for generators who wished to connect into the Norwich Zone.

Connecting via ANM means occasional curtailment of a generator’s power output following network constraints. The curtailment assessments therefore equip the generators with estimates of the annual energy curtailment throughout the lifetime of their projects.

The FDG Norwich Zone has seen huge demand for DG connections including wind, solar, biomass, and anaerobic digestion. As the number of connected distributed generators has grown, the available grid capacity for new generators to connect, without significant network reinforcement, has decreased.

Typical capacity constraints identified in planning studies include thermal (where the rating of power lines or transformers could be exceeded), reverse power flow (where the network is not designed to operate with increased levels of power flowing from a lower voltage level to a higher one) and voltage rise (where the voltage level could breach statutory voltage limits). Each connection applicant could cause one or more of these constraints, if not actively managed.

The connection applicant must pay for any grid reinforcement at their connecting voltage level and one voltage up. Reinforcement beyond that is the responsibility of UKPN (the distribution utility) who must make a business case to the regulator.

A business case is often difficult to make without a clear indication that the asset will be fully utilised. Connection applicants are facing expensive and time-consuming grid upgrades to connect, as a result of both their local and wider reinforcement works.

ANM allows generators to connect to networks where a firm connection has become technically and/or financially unviable. When network operation nears constraint conditions, ANM uses real-time, autonomous and deterministic control to regulate export from participating generators and maintain the network within safe operating conditions. The ANM solution will manage the output of the flexible generators under intact network conditions and certain outage conditions on 400/132 kV super grid transformers (SGTs).

As well as providing generators with a managed connection based on real-time control, UKPN is able to provide the connection applicant with an estimate of how often their export capacity will be curtailed. These estimates help the developers with their long-term planning and typically show a very low anticipated reduction in annual energy export capacity.

The ANM platform provides constraint management that delivers benefits such as:

Fast-acting response to minimise curtailment: ANM delivers second by second control and issues new generator set points every 600ms.

Repeatable and Transparent: ANM does not rely on a network model and load flow simulation. ANM provides consistent and predictable control actions under recurring conditions. This ensures safe and reliable operation of the network under all conditions.

Scottow Moor solar farm, one of the UK’s largest, consists of more than 130,000 ground-mounted solar panels and new underground connections to the local UKPN electricity network. For phase 1 of the solar farm, ANM is connecting 20MW of the 32MW. The flexible connection provided by ANM has meant that the solar farm was built and connected to the grid in just 7 weeks, making it one of the fastest large-scheme builds across the UK and Europe.

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