Power Glossary
- Annualised advance - AA
- is the rate of consumption for a settlement register over the period between two Meter readings. The value is nominally expressed as kWh/Year.
- Accepted bids volume - ABV
- for a period is the sum of all the individual bid-offer acceptance volumes (BOAL) for the bids accepted by the system operator in the period.
- Annual demand ratios - ADR
- is a measure of the variation between the total annual profiled non half hourly (NHH) consumption and the total annual metered NHH consumption.
- Accepted offers volume - AOV
- for a period is the sum of all the individual bid-offer acceptance volumes (BOAL) for the offers accepted by the system operator in the period.
- Ave noon effective temperature
- relates to Eastern GSP Group (_A) and is included to highlight any potential correlation with market conditions.
- Balancing mechanism - BM
- is a period of time which allows the system operator to call upon additional generation/consumption or reduce generation/consumption in order to balance the system minute by minute.
- Balancing mechanism unit - BM unit
- 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.
- Balancing mechanism reporting agent - BMRA/BMRS
- provides near real time and historic data about the Balancing mechanism.
- Bid offer acceptance - BOAL/BOALF
- is a formalised representation of the purchase and/or sale of offers and/or bids (see BOD) by the system operator in its operation of the Balancing mechanism. Each bid-offer acceptance is shown on the BMRS as a MW level of operation at the beginning and at the end of the acceptance (and for any intermediate points which may be necessary).
- Bid offer data - BOD
- Bid-offer data for a BM unit and settlement period is made up of a series of bid-offer pairs; there may be up to five above FPN and up to five below FPN in each set of BOD. A bid-offer pair consists of an identifying number (e.g. 1, 2 or –1), a ‘band width’ in MW, and both an offer price and a bid price. The offer price is the price at which the system operator may purchase energy within this band; the bid price is the price which will be paid for energy accepted from the system operator within this band.
- Balancing and settlement code - BSC
- is the legal document setting out the rules for the operation and governance of the balancing mechanism and imbalance settlement. All licensed electricity generators and suppliers must sign up to the BSC and other interested parties may also choose to do so.
- Balancing and settling code company - BSCCo
- is defined and created by the balancing and settlement code (BSC) in March 2001. A non-profit organisation responsible for managing the provision of the necessary central systems and services to give effect to the BSC rules and for managing the governance processes.
- Calculated indebtedness
- is an estimated of total trading charges over 29 calendar days owed to or by each party.
- Credit assessment price - CAP
- a price expressed in £/MWh and provided by the BSCCo for the purpose of calculating actual energy indebtedness.
- Combined cycle gas turbine - CCGT
- is a collection of generating units (registered as a CCGT Module) comprising one or more gas turbine units (or other gas based engine units) and one or more steam units where, in normal operation, the waste heat from the gas turbines is passed to the water/steam system of the associated steam unit or steam units and where the component units within the CCGT module are directly connected by steam or hot gas lines which enable those units to contribute to the efficiency of the combined cycle operation of the CCGT module.
- Central data collection agent - CDCA
- is responsible for collecting, validating and aggregating data from metering systems registered by BSC trading parties.
- Central Volume Allocation - CVA
- is a metering system (at a Boundary Point or a Systems Connection Point) which is to be registered in the central meter registration service. CVA meters measure imports/exports on a half-hourly basis. The data is collected by the Central Data Collection Agent (CDCA) and is used for settlement purposes. All CMRS registered meters must be associated with a BM Unit.
- Estimated rate of consumption - EAC
- is nominally expressed in kWh/Year and is used in settlement until an annualised advance is calculated.
- Excess credit
- is the amount of credit that is required to cover calculated indebtedness.
- First settlement run - SF run
- the first settlement run that results in money changing hands. Note this isn’t the last run, as a series of reconciliation runs take place later.
- Final physical notification - FNP
- the final physical notification for BM unit is the level of import or export (as the case may be) that the party expects to import or export from BM unit.
- GSP group correlation factor - GGCF
- is a factor which is applied to the demand to account for inaccuracies in the readings when the volatge is steeped down.
- Gross cashflow
- is the sum of the total imbalance, total residual cashflow reallocation cashflow and balancing cashflow.
- Grid supply point - GSP
- is where the National Grid ends and electricity is distributed via the local area network. Line losses occur during the transmission from the national to the local network as the voltage is stepped down to a usable current.
- HH
- half hourly.
- Indicated imbalance forecast - IMBALNGC
- the Indicated Imbalance forecast for each period is the difference between the sum of the PNs submitted for generation BM Units (i.e. the indicated generation), and the national demand forecast made by the system operator.
- Indicated demand forecast - INDDEM
- the Indicated Demand forecast for each period is the sum of all the PNs submitted for BM units which are forecast to be importing energy, presented as a single average MW level for the settlement period.
- Indebtedness error
- is the difference between the calculated indebtedness (as per the credit calculation) and the actual indebtedness using the SF based actual value of the charges accrued.
- Indebtedness exposure
- is the Indebtedness that is not covered by credit cover or by the credit cover calculation. This is the value of potential market exposure had there been defaults.
- Indicated generation forecast -INDGEN
- The Indicated Generation forecast for each period is the sum of all the PNs submitted for BM units which are forecast to be exporting energy, presented as a single average MW level for the settlement period.
- Indicated margin forecast - MELNGC
- the indicated margin forecast for each settlement period is the difference between the sum of the MELs submitted for that period, and the national demand Forecast made by the System Operator. The greater the value, the higher the margin between available generation capacity and forecast demand – that is to say, the more spare capacity there is forecast to be in the system.
- Initial national demand out-turn - INDO
- is the half-hour average MW demand metered by the transmission company taking into account transmission losses but not including station transformer load, pumped storage demand or Interconnector demand.
- Initial transmission system demand out-turn - ITSDO
- is the average megawatt value of demand for a settlement period including transmission losses, station transformer load, pumped storage demand and interconnector demand.
- Maximum export limit - MEL
- is a series of MW figures and associated times, making up a profile of the maximum level at which the BM unit may be exporting (in MW) to the GB transmission system at the grid supply point.
- Meter point administration number -MPAN
- is a unique number to each property.
- National demand forecast - NDF
- is made by the system operator. The system operator national demand forecast is based on historically metered generation output for Great Britain. This value includes transmission losses, but excludes Interconnector flows and demand from station transformers and pumped storage units.
- National grid company - NGC
- is an international electricity and gas company and one of the largest investor-owned energy companies in the world.
- NHH
- non half hourly.
- Net imbalance volume
- is calculated as the sum of accepted bids, accepted offers and price volume adjusters.
- Physical notification - PN
- means, in respect of a settlement period and a BM unit, a notification made by (or on behalf of) the lead party to the transmission company under the grid code as to the expected level of export or import, as at the transmission system boundary, in the absence of any acceptances, at all times during that settlement period.
- Power purchase agreement - PPA
- is a legal contract between an electricity generator (provider) and a power purchaser (host). The power purchaser purchases energy, and sometimes also capacity and/or ancillary services, from the electricity generator. Such agreements play a key role in the financing of independently owned (i.e. not owned by a utility) electricity generating assets.
- System buy price
- is the weighted average of accepted offers in settlement period.
- System buy price short volume
- is the daily sum across the market of the energy imbalance volume charged at system buy price.
- System sell price
- is the weighted average of accepted bids in settlement period.
- System sell price long volume
- is the daily sum across the market of the energy imbalance volume charged at system sell price.
- Supplier volume allocation - SVA
- meters that are not (or are not allowed to be) registered under CMRS must be registered under SMRS. Additionally, only licensed suppliers may register a meter under SMRS. All SMRS registered meters must be associated with a supplier BM Unit, which in turn must be associated with a Grid Supply Point Group.
- System operator - SO
- The system operator is responsible for ensuring the short term security of supply on the grid including dispatching offered generation to match demand and minimise the total cost of generation. Currently this is the National Grid Company.
- Transmission loss factor - TLF
- is that factor used to allocate transmission losses on a locational basis to BM unit in settlement period.
- Transmission loss multiplier
- is the factor applied to BM unit in settlement period in order to adjust for transmission losses.
- Total balancing cashflow
- is the gross of payments relating to accepted bids and offers.
- Total imbalance cashflow
- is the gross energy imbalance payments made to and from parties.
- Total residual cashflow reallocation cashflow - Total RCRC
- is the amount recovered or paid back to parties in offer to balance total trading charges to zero each settlement period.
- Transmission system demand forecast -TSDF
- is made by the system operator. The system operator transmission system demand forecast is based on historically metered generation output for Great Britain. This value includes interconnector flows and demand from station transformers and pumped storage units.
