Flexible Connections

The Orkney ANM project was implemented as an alternative solution to disproportionately costly distribution network reinforcements. The Orkney ANM system measures the power flows at several measurement points on the network and controls multiple renewable generators that are part of the scheme. The network is divided into different zones to manage electricity flow and prevent overloads. These zones are essentially constraint points within the network, each representing a section of the grid that could potentially become overloaded due to additional generation.  The zones are indicated on the map provided:

The Northern Isles New Energy Solutions (NINES) project was an innovation project developed by SSEN Distribution aimed at transforming the energy landscape of the Shetland Islands. Historically the Shetland Islands have been faced with a significant energy supply challenge. They are located some 130 miles to the north of the British mainland and are not connected to the Great Britain electricity system, and therefore rely on local sources of generation.

The NINES project delivered an Active Network Management (ANM) system, which manages multiple constraints across both overhead lines and underground cables on the 33kV and 11kV distribution network that connects the smaller islands to the main island. Like other distribution ANM schemes, when the power flow through a constrained area of the network approaches network limits, the ANM will curtail generation to avoid breaching those limits. 

The Western Isles location ANM is in place on the islands of Lewis and Harris. The ANM system on the Western Isles has been put in place to manage real time power flow on the network and protect the network should there be an outage on critical equipment or the subsea cable. Customers looking to connect in this network area may be subject to ANM. 

The SWAN scheme has been developed by SSEN Distribution to allow connecting generation customers to meet a requirement set by National Grid Electricity Transmission (NGET).

The requirement stipulates the need for suitable monitoring and control of connections within set ranges calculated by NGET, at key parts of SSEN Distribution’s southern distribution network. The SWAN ANM system allows for the automated real time management of generation to maintain an electrical network within operational constraints. SWAN will operate when NGET issues a control signal to SSEN Distribution to curtail or de-energise generation as required. The curtailment is calculated by comparing real time power flows against the capacity limit of NGET’s network. If the power flows are greater than the available capacity, then it is necessary to reduce the power flow onto NGET’s network. The 8 Grid Supply Points (GSP’s) which SWAN ANM covers are indicated on the map provided:

The Isle of Wight ANM was developed as an alternative to reinforcement to allow quicker access for those generators wishing to connect to SSEN Distribution’s network. Before the ANM, the distribution network on the Island was heavily constrained on generation, preventing the connection of new distributed generation sites without triggering high-cost distribution network reinforcement.  Measurement points have been installed on each of the three 132kV subsea cables that connect the Isle of Wight to the Fawley Grid Supply Point in Southampton on the mainland. If the power flow approaches network limits on these circuits, the ANM system sends control signals to curtail generation so that network limits are not breached.

 

To reduce connection delays for new distributed generation (generators connecting to the distribution network), NGET required an ANM scheme at Minety GSP.  Minety GSP contains a high level of distributed generation which means reverse power flows from the Distribution to the Transmission network are common. NGET identified potential constraints at the four 400/132kV Super Grid Transformers if more generation was to connect.  

 

To enable queued generation to proceed with their connections, SSEN Distribution has installed a Reverse Power Flow control scheme which manages transmission constraints at four Super Grid Transformers (SGTs).