National Grid procures Balancing Services in order to balance electricity supply and demand and ensure the security and quality of electrical supply across the GB Transmission system in an economic and efficient manner. There are two types of balancing actions. Energy imbalance actions adress overall mis-matches between generation and demand at a national level. System imbalance actions tackle local or regional constraints in the capacity of the transmission network. Transmission Constraint Management is one type of system Balancing Service.
Constraint management is required where the electricity transmission system is unable to transmit the power supplied to the location of demand due to congestion at one or more parts of the transmission network. In the event that the system is unable to flow electricity in the way required, National Grid will take actions in the market to increase and decrease the amount of electricity at different locations on the network.
One action that National Grid can take is to enter into contracts to agree output with a service provider ahead of time to aid the management of a transmission constraint.
Constraint management contracts enable National Grid to agree in advance technical parameters with connected parties to facilitate the management of a constraint. The most common style of contract is to agree either a cap or collar on the output of a power station.
Whilst other commercial tools are available to manage the output of a power station such as trading or taking actions in the balancing mechanism, constraint management contracts are considered where the cost of the action is more economic if it can be agreed in advance.
There are multiple different styles of constraint management service which National Grid may utilise to resolve a specific requirement. A more detailed description of the service and generic contract terms are available to download from the links below. Due to the unique nature of constraint management requirements, services and contracts will be developed to reflect the individual requirement.
Constraint Management Service Description
Generic Constraint Management Terms
Generic Voltage Constraint Management Terms - Firm
Generic Voltage Constraint Management Terms - Optional
Generic Voltage Constraint Management Terms - with Frequency Response
Contact us : Commercial.Operation@nationalgrid.com
Tel: 01926 654611
Constraint Management requirements are linked to specific system needs so will be advertised on an ad hoc basis to match each requirement rather than following a regular timetable. Potential providers will be approached by National Grid and where there is sufficient competition National Grid will seek to contract via a market mechanism. In other circumstances, bilateral contracts will be entered into with service providers.
Invitations to tender and information regarding historic and existing contracts can be found under the Market Information tab.
National Grid will look to manage constraints requirements via constraint management tenders or bilateral agreements, in an economic and efficient manner. The accepted providers will be selected with the aim of ensuring the total costs of managing system constraints are lower than without the procurement of constraint management services.
The principles for the assessment of voltage constraint management services can be found in the following document:
Voltage Constraint Management Assessment Guidelines
The structure of the payment will be determined by the style of the constraint management contract required. Some examples of the possible payment rates are:
Payments will be made following the standard settlement for balancing services which is paid on a monthly basis. A Final Statement, along with the self-bill invoices, is issued by the eighteenth business day of the following month that the service was provided. More information regarding settlement can be found by clicking here.
Data regarding the monthly costs of Constraint Management can be found in the Monthly Balancing Services Summary which can be found by clicking here.