Balancing Mechanism (BM) Units are used as units of trade within the Balancing Mechanism. Each BM Unit accounts for a collection of plant and/or apparatus, and is considered the smallest grouping that can be independently controlled. As a result, most BM Units contain either a generating unit or a collection of consumption meters. Any energy produced or consumed by the contents of a BM Unit is accredited to that BM Unit.
BM Units can be classed as either a Primary BM Unit or a Secondary BM Unit. There are several types of BM Unit, each representing different aspects of the system. They are: Directly Connected; Embedded; Interconnector; Supplier; Secondary; and Miscellaneous.
Primary BM Units
Primary BM Units are the units used under the Balancing and Settlement Code (BSC) to account for all energy that flows on or off the Total System (the Transmission System and each Distribution System combined). A Primary BM Unit is the smallest grouping of generation and / or demand equipment that can be independently metered for Settlement and all generation and demand equipment must be captured in a Primary BM Unit.
Secondary BM Units
Secondary BM Units can only be registered by Virtual Lead Parties (VLPs). Supplier Volume Allocation (SVA) Half Hourly (HH) metered generation and / or demand equipment within a single GSP Group can be allocated to a Secondary BM Unit for the purpose of providing Trans-European Replacement Reserves Exchange (TERRE) Balancing Services to the National Electricity Transmission System Operator (NETSO).
Systems Connection Points
A Systems Connection Point is a point of connection between two or more Systems excluding points of connection between Distribution Systems in the same GSP Group or a point of connection between Offshore Transmission System User Assets and the Transmission System. There are three types of Systems Connection Points:
- Grid Supply Points (GSPs) – these are points of connection between the Transmission System and a Distribution System
- Offshore Transmission Connection Point (OTCP) – these are a GSP where the Systems Connection Point is between a Distribution System and an Offshore Transmission System. Note, at an OTCP the Metering System is registered by NETSO as opposed to the LDSO
- Distribution Systems Connection Points (DSCPs) – these are points of connection between two Distribution Systems
How are BM Units categorised?
There are several types of BM Unit, each covering different aspects of the system. Each is marked with a particular prefix to its ID, as shown below:
| BM Unit |
Prefix |
Description |
| Directly Connected |
T_ |
These BM Units are directly connected to the Transmission System. |
| Embedded |
E_ |
These BM Units are embedded into a Distribution System. |
| Interconnector |
I_ |
These BM Units are related to an Interconnector. |
| Supplier |
2_ |
These BM Units cover Supply, and contain all of a particular Supplier’s MPANs in either a Base or Additional Supplier BM Unit for a given Grid Supply Point (GSP) Group. |
| Supplier |
C_ |
These Additional Supplier BM Units are registered solely for the purpose of allocating CFD Assets to them. |
| Secondary |
V_ |
Secondary BM Units may be registered by a Virtual Lead Party to provide TERRE Balancing Services to the NETSO. |
| Miscellaneous |
M_ |
Other types of BM Units that don’t fit the above categories. This prefix does not apply to newly registered BM Units. |
A complete list of all active BM Units can be found on the Elexon Portal.
How do I register BM Units?
The BM Unit Registration process is described in BSCP15 ‘BM Unit Registration‘, which covers the procedures and timescales for registering BM Units.
Registering a Primary BM Unit normally requires a lead time of 30 Working Days (60 Working Days if BM Unit configuration is Non-Standard), and you will need to speak to the NETSO before this process begins where you are participating in the Balancing Mechanism, so you should leave plenty of time to complete the whole process. You can register BM Units using form BSCP15/4.1, which must be sent to the Central Registration Agent ([email protected]).
Registering a Secondary BM Unit requires a lead time of 15 Working Days and you will normally need to speak to the NETSO before this process begins, so you should leave plenty of time to complete the whole process. You can register BM Units using form BSCP15/4.14, which must be sent to the Central Registration Agent ([email protected]).
Guidance on the BM Unit registration process, including filling in BSCP15/4.1 and BSCP15/4.14, along with further information about BM Units, can be found in our BM Unit Guidance.
If you are a new Supplier joining the market, you will need to set up 14 Supplier Primary BM Units (your Base Primary BM Units, one for each GSP Group) as part of your registration. You can register all other Supplier Primary BM Units on an ad-hoc basis as and when they are required.
If you are looking to register Primary BM Units for Electricity Market Reform (EMR) purposes please see the Registration of BM Units for EMR guidance. If your CFD Asset is to be registered in CMRS, you need to follow the same process as for non-CFD Assets. If your CFD Asset is to be registered in SMRS there is an EMR specific registration process for your Primary BM Unit. For naming convention for Additional BM Units registered for CFD Assets please click here.
What are the timescales for registering BM Units?
Registering a T_, E_ or I_ Primary BM Unit requires a lead time of 30 Working Days and 60 Working Days for a non-standard Primary BM Unit, you will normally need to speak to NETSO before this process begins, so you should leave plenty of time to complete the whole process.
Additionally if a Metering Dispensation needs to be sought for the site, refer to the Exemptions and transfers: Metering Dispensations page for the timescales associated with this.
A standard Primary BM Unit includes the following:
- Generating Unit
- Closed Cycle Generating Turbine (CCGT) Module
- Power Park Module (PPM)
- Power Station Transformers (Station Transformers)
- Directly Connected Demand at a single Boundary Point
- Combined Offshore BM Unit (COBMU)
- Directly connected Demand at more than one Boundary Point provided that the total Imports are equal to or less than 50MW in England and Wales, 30MW in South Scotland and 10MW in North Scotland
- Supplier (Base or Additional) Primary BM Unit
- Interconnector Primary BM Unit
- Annex I-2 BETTA BM Units
- An Offshore PPM or COBMU and its associated Low Voltage Assets
- Combination of Generating Units connected to the Total system provided that the total Exports are equal to or less than 50MW in England and Wales, 30MW in South Scotland and 10MW in North Scotland
- Electricity Storage Module provided that the total Exports are equal to or less than 50MW in England and Wales, 30MW in South Scotland and 10MW in North Scotland
- Hybrid Plant – PPM or combination of Generating Units plus Storage Module provided that the total Exports are equal to or less than 50MW in England and Wales, 30MW in South Scotland and 10MW in North Scotland
Other Primary BM Units may be non-standard and their configuration needs to be agreed by the ISG. Please contact [email protected] for advice on whether a Primary BM Unit is standard or a non-standard configuration.
The Go-live date for registering a 2_ or C_ Primary BM Unit needs to align with the MDD Go-Live Date. These Primary BM Units follow the MDD fast-track process.
To register these Primary BM Units, you need to submit MDD forms and a BSCP15/4.1 form.
The MDD form needs to be submitted in line with the MDD timetable.
A Supplier Primary BM Unit may also be registered with the NETSO. If you have a NGC BM Unit ID, your BSCP15/4.1 form needs to be submitted at least 30 Working Days before the Go live date.
If you are not registering your Primary BM Unit with the NETSO and you do not have a NGC BM Unit ID, your BSCP15/4.1 form needs to be submitted at least 15 Working Days before the Go-live date.
Registering a V_ Secondary BM Unit requires a lead time of 15 Working Days.
If you are registering your BM Unit with the NETSO, you will need to speak to them to obtain the NGC BM Unit Id and begin their registration process.
How do I register for Systems Connection Points?
What are the timescales for registering Systems Connection Points?
The registration of a new GSP needs to be initiated at least five Working Days (WD) before the Commissioning Programme Commencement date. If a Metering Dispensation needs to be sought, refer to the Metering Dispensations page for the timescales associated with this. Metering and Aggregation Rule steps need to be initiated at least 20 WD before the proposed energisation date.
A new circuit at a GSP and associated Metering and Aggregation Rules need to be registered at least 20 WD before the proposed energisation date, although if a Metering Dispensation needs to be sought, refer to the Metering Dispensation page for the timescales associated with this.
The registration of a new DSCP or new circuit at a DSCP and associated Metering and Aggregation Rules need to be initiated at least 20 WD before the energisation of the first circuit at the DSCP, although the Line Loss Factors associated with the new DSCP (or any new or changes to Line Loss factors for a new circuit) need to be registered at least 50 WD before the proposed energisation date. If a Metering Dispensation needs to be sought, refer to the Metering Dispensation page for the timescales associated with this.
