PERFORMANCE ASSURANCE: ANNUAL DEMAND RATIO (ADR) |
Guidance Note |
How Elexon makes use of an annualised form of Group Correction Factor (GCF) – Annual Demand Ratio (ADR) – as a Key Performance Indicator (KPI) for Settlement Accuracy
The basic principles of GCF including its intended purpose, how it is calculated, who it affects and how it affects them
How anomalies in ADR can be an indicator of Settlement Error, and the steps that Elexon takes to investigate these
Details of the various Performance Assurance Techniques (PATs) Elexon operates to mitigate the likelihood of Settlement Error occurring, which are covered in their own Guidance Notes
Errors in the setup of Metering Systems or Metering System faults that lead to consumption or generation volumes being recorded incorrectly
Errors in the standing data associated with Metering Systems, meaning that consumption or generation volumes are recorded correctly but processed into Settlement incorrectly or not at all
Prolonged and/or inaccurate estimation of consumption or generation volumes where metered data is not available
Grid Supply Points (GSPs) where energy enters the Distribution System from the Transmission System
Embedded Balancing Mechanism Units (E_BMUs), exceptionally large generators and (more rarely) consumers “embedded” within the Distribution Systems
Distribution System Connection Points (DSCPs) where energy moves from one Distribution System to another
Whether the volumes are Settled NHH or HH
The Measurement Class of the supply (based on its size and what kind of metering equipment is fitted)
Whether the data is Actual or Estimated
Whether the data is for consumption or generation volumes
Whether the data is for metered volumes or line losses
GSPGT is calculated from (mostly) actual HH data, from fewer meters, all of which have multiple redundancies and safeguards built in
The portion of CCC ID volumes Settled HH is also calculated from (mostly) actual HH data, from fewer meters, the largest of which also have multiple redundancies and safeguards built in
The portion of CCC ID volumes Settled NHH, by contrast, is calculated by applying a statistical profile to annualised volumes calculated from meter advances
1+((100-(50+25+5))/((50*0)+(25*1)+(5*1.2))) or
1+((100-80)/(0+25+6)) or
1+(20/31) or
1.6452
For energy from CCC IDs with a WTN of 0 (the most likely to be correct): 50*(1+((1.6452-1)*0)) or
50*(1+(0.6452*0)) or
50*1 or
50
For energy from CCC IDs with a WTN of 1: 25*(1+((1.6452-1)*1)) or
25*(1+(0.6452*1)) or
25*1.6452 or
41.129
For energy from CCC IDs with a WTN of 1.2 (the least likely to be correct): 5*((1.6452-1)*1.2)) or
5*(1+(0.6452*1.2)) or
5*1.7742 or
8.871
YMNHHC is (100-50=) 50
YPNHHC is 30
ADR is (50/30=) 1.6 recurring
One or more of the underlying calculations is not being performed correctly; and/or
One of more of the underlying calculations contains incorrect data
Potential Error | Accountable Party | Impact on Settlement Data | Controls | Settlement Risk(s) |
SVAA calculates ADR incorrectly | Elexon | ADR does not match underlying Settlement Data | Elexon has access to underlying Settlement data and is able to replicate the ADR calculation to check it has been carried out correctly | CEN-02 |
Potential Error | Accountable Party | Impact on Settlement Data | Controls | Settlement Risk(s) |
CDCA calculates GSPGT incorrectly | Elexon | GSPGT figure provided by the CDCA does not match aggregated VAU volumes | Elexon has access to underlying Settlement data and is able to replicate the GSPGT calculation to check it has been carried out correctly | CEN-03 |
The Agg Rule for GSPGT is incorrect or out-of-date | LDSO | GSPGT trends differently to other elements of the overall ADR calculation | Elexon periodically reviews GSPGT Agg Rules, especially when VAUs are amended, added or removed | REG-02 |
The Agg Rule for one or more VAUs is incorrect or out-of-date | Registrant | VAU volumes trend similarly to GSPGT, which itself trends differently to other elements of the overall ADR calculation | Elexon reviews new Agg Rules and any changes to existing rules. Technical Assurance of Metering (TAM) Audit1 | REG-02 |
Metered data is incorrect due to a fault with one or more Metering Systems comprising a VAU, or an error in the Meter Technical Details or other standing data for one or more Metering Systems used to calculate VAU volumes, including where Metering Dispensations are applied incorrectly | Registrant | Unexplained step-changes in VAU volume. GSPGT trends differently to other elements of the overall ADR calculation | Elexon’s Change Point Tool (which uses machine learning to monitor for step-changes in GSP volumes). Elexon has access to Settlement Data from DSCPs and E_BMUs and can check these manually. BSC Audit. TAM Audit and targeted metering inspections by the Technical Assurance Agent (TAA) | REG-01, REG-03, MET-01, MET-02, MET-03, MET-04 |
Prolonged estimation at one or more Metering Systems comprising a VAU leads to unrepresentative data entering Settlement | Registrant | Step-changes in VAU volume consistent with estimation to trend or zero. GSPGT trends differently to other elements of the overall ADR calculation | Change Point Tool for GSPs. Elexon has access to Settlement Data from DSCPs and E_BMUs and can check these manually. Elexon periodically reviews the CDCA’s Fault and Estimation Logs for long-term issues with metering communications equipment | DAT-01 |
CDCA incorrectly estimates data for one or more Metering Systems comprising a VAU | Registrant | Step-changes in VAU volume consistent with estimation to trend or zero where this is not the appropriate method of estimating data, or is not otherwise reflective of prior volumes. GSPGT trends differently to other elements of the overall ADR calculation | Change Point Tool for GSPs. Elexon has access to Settlement Data from DSCPs and E_BMUs and can check these manually. Elexon periodically reviews the CDCA’s Estimation Log to check the correct method is used | DAT-02 |
Potential Error | Accountable Party | Impact on Settlement Data | Controls | Settlement Risk(s) |
Suppliers do not collect or submit sufficient data from Metering Systems | Supplier | Poor Settlement Performance. Over-use of Default EACs (NHH only). Aggregated consumption or generation from relevant CCC IDs trends differently to other elements of the overall ADR calculation | Elexon monitors Suppliers’ Settlement Performance and deploys PATs such as Error and Failure Resolution (EFR) as necessary to address poor performance. BSC Audit | REG-03, REG-04, REG-05, DAT-01, DAT-03 |
Suppliers or DAs incorrectly annualise volumes from NHH Metering Systems when profiling consumption or generation data | Supplier | Poor NHH Settlement Performance. Step-changes in NHH volumes. Increase in reported volumes from excessively large Annualised Advances (AAs) and Estimates of Annual Consumption (EACs). Aggregated consumption or generation from relevant CCC IDs trends differently to other elements of the overall ADR calculation | Elexon monitors Suppliers’ Settlement Performance and deploys PATs such as Error and Failure Resolution (EFR) as necessary to address poor performance. Elexon notifies Suppliers of the proportion of their NHH volumes Settled on excessively large AAs and EACs. BSC Audit | DAT-02, DAT-03 |
DAs do not submit sufficient data from Metering Systems into Settlement ("DA Defaults") | Supplier | Step-changes in HH Settlement Performance, volumes and MSID counts | SVAA notifies Elexon of DA Defaults | DAT-03 |
Metered data is incorrect due to a fault with one or more Metering Systems, or an error in the Meter Technical Details or other standing data for one or more Metering Systems used to calculate volumes | Supplier | Unexplained step-changes in aggregated consumption or generation from relevant CCC IDs. Aggregated consumption or generation from relevant CCC IDs trends differently to other elements of the overall ADR calculation | BSC Audit. TAM Audit (HH MC C Controls only) | REG-01, REG-03, MET-01, MET-02, MET-03, MET-04 |
LDSO uses a non-Compliant methodology to calculate LLFs | LDSO | Unexplained step-changes in aggregated line losses from relevant CCC IDs. Aggregated line losses from relevant CCC IDs trend differently to other elements of the overall GCF calculation | LLF Audit | CEN-01 |
DA applies LLFs incorrectly | Supplier | Unexplained step-changes in aggregated line losses from relevant CCC IDs. Aggregated line losses from relevant CCC IDs trend differently to other elements of the overall GCF calculation | BSC Audit | DAT-03 |
Energy theft is detected, but volumes are not reported into Settlement | Supplier | ADR trends above tolerance. GSPGT trends differently to other elements of the overall ADR calculation | BSC Audit | DAT-05 |
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Affected GSP Group | Approximate Start Date |
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Potential Root Cause | Check | Yes/No? | Notes/Further Actions |
The SVAA has calculated ADR incorrectly | Does the ADR value provided by the SVAA equal YMNHHC/PMNHHC? |
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The SVAA has calculated YMNHHC incorrectly | Does the YMNHHC value provided by the SVAA match the value of GSPGT provided by the CDCA (where this is correct) minus the annual sum of metered volumes and line losses for CCC IDs associated with HH Metering Systems and UMS? |
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The SVAA has calculated PMNHHC incorrectly | Does the YPNHHC value provided by the SVAA match the annual sum of metered volumes and line losses for CCC IDs associated with NHH Metering Systems and UMS |
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The CDCA has calculated GSPGT incorrectly | Does the GSPGT value provided by the CDCA match the sum of relevant CVA metered volumes in line with the GSP Group Aggregation Rule? |
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The Aggregation Rule used by the CDCA to calculate GSPGT is incorrect | Is the GSP Group Aggregation Rule held by Elexon correct? Has the correct Group Aggregation Rule been provided to the CDCA? |
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The Aggregation Rules used by the CDCA to calculate volumes for one or more VAUs are incorrect | Are the Aggregation Rules for relevant CVA Metering Systems Correct? Have the correct Metering System Aggregation rules been provided to the CDCA? Are the CDCA using the correct Metering System Aggregation Rules? |
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VAU volumes are incorrect due to a fault with one or more Metering Systems, or an error in the Meter Technical Details (MTDs) or other standing data for one or more Metering Systems | Is annualised GSPGT trending differently to other elements of the overall ADR calculation? Has there been a step-change in GSPGT consistent with the direction and timeframe of the anomaly? Has there been a step-change in metered volumes (including direction of flow) at any of the relevant CVA Metering Systems consistent with the direction and timeframe of the anomaly? Have the TAA carried out onsite audits of the relevant CVA Metering Systems since the date at which ADR began to trend away from one or sharply changed direction? Are there any outstanding faults with any of the relevant CVA Metering Systems consistent with the direction, scale and timeframe of the anomaly? |
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VAU volumes are incorrect due to prolonged estimation at one or more Metering Systems | Has metering data for any of the relevant CVA Metering Systems been estimated for a prolonged period? Has this estimation resulted in a step-change in metered volumes (including direction of flow) consistent with the direction, scale and timeframe of the anomaly? |
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VAU volumes for one or more Metering Systems have been incorrectly estimated by the CDCA | Where estimated data is being returned for a relevant CVA Metering System, are the CDCA using the correct estimation method as specified by the Code? Has this estimation resulted in a step-change in metered volumes (including direction of flow) consistent with the direction, scale and timeframe of the anomaly? |
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Aggregate SVA metered volumes and/or line losses for one or more Measurement Classes are incorrect | Is the annual sum of metered volumes and/or line losses for the CCC IDs associated with a particular class of Metering System or UMS trending differently to other elements of the overall ADR calculation? Has there been a step-change in one or more of these aggregate volumes consistent with the direction, scale and timeframe of the anomaly? |
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GSP Group | LDSO | LDSO Market Participant ID (MPID) | Former Regional Electricity Board |
_A | Eastern Power Networks plc | EELC | Eastern ELeCtricity Board |
_B | National Grid Electricity Distribution (East Midlands) | EMEB | East Midlands Electricity Board |
_C | London Power Networks Plc | LOND | LONDon Electricity Board |
_D | SP Manweb Plc | MANW | Merseyside And North Wales Electricity Board |
_E | National Grid Electricity Distribution (West Midlands) | MIDE | MIDlands Electricity Board |
_F | Northern Powergrid (Northeast) Plc | NEEB | North Eastern Electricity Board |
_G | Electricity North West Limited | NORW | NORth Western Electricity Board |
_H | Southern Electric Power Distribution Plc | SOUT | SOUThern Electricity Board |
_J | South Eastern Power Networks Plc | SEEB | South Eastern Electricity Board |
_K | National Grid Electricity Distribution (South Wales) | SWAE | South Wales Electricity Board |
_L | National Grid Electricity Distribution (South West) | SWEB | South Western Electricity Board |
_M | Northern Powergrid (Yorkshire) Plc | YELG | Yorkshire ELectricity Group (formerly the Yorkshire Electricity Board) |
_N | SP Distribution Plc | SPOW | Scottish POWer (formerly the South of Scotland Electricity Board) |
_P | Scottish Hydro Electric Power Distribution Ltd | HYDE | North of Scotland HYDro-Electric Board |
Aggregation Rule for a VAU with a single circuit: Metered Volume = (AE – AI)
Aggregation Rule for a VAU with a two circuits: Metered Volume = (AE – AI) + (AE – AI)
Aggregation Rule for a VAU with a single circuit but metering above another VAU with a single (metered) circuit: Metered Volume = (AE – AI) - (AE – AI)
GSP1 Metered Volume = (AE-AI)
GSP2 Metered Volume = (AE-AI)
DSCP1 Metered Volume = (AE-AI)
E_BM Unit Metered Volume = (AE x LLF1 – AI x LLF2)
GSP Group Metered Volume = GSP1 + GSP2… +/- DSCP1…
GSP Group Take Metered Volume = GSP Group Metered Volume – E_BM Units
CCC ID | Data Aggregation Type | Measurement Class | Actual or Estimated | Type of Consumption or Generation | GSP Group Scaling Factor |
17 | NHH | A | Estimated | Metered consumption | 1 |
18 | NHH | A | Actual | Metered consumption | 1 |
20 | NHH | A | Estimated | Metering system non-specific line losses for metered consumption | 1.2 |
21 | NHH | A | Actual | Metering system non-specific line losses for metered consumption | 1.2 |
32 | NHH | A | Estimated | Metered generation | 0 |
33 | NHH | A | Actual | Metered generation | 0 |
34 | NHH | A | Estimated | Metering system non-specific line losses for metered generation | 0 |
35 | NHH | A | Actual | Metering system non-specific line losses for metered generation | 0 |
19 | NHH | B | Estimated | Unmetered consumption | 1 |
22 | NHH | B | Estimated | Metering system non-specific line losses for unmetered consumption | 1.2 |
1 | HH | C | Actual | Metered consumption | 0 |
3 | HH | C | Actual | Metering system specific line losses for metered consumption | 0 |
4 | HH | C | Actual | Metering system non-specific line losses for metered consumption | 0 |
6 | HH | C | Actual | Metered generation | 0 |
7 | HH | C | Actual | Metering system specific line losses for metered generation | 0 |
8 | HH | C | Actual | Metering system non-specific line losses for metered generation | 0 |
9 | HH | C | Estimated | Metered consumption | 0 |
11 | HH | C | Estimated | Metering system specific line losses for metered consumption | 0 |
12 | HH | C | Estimated | Metering system non-specific line losses for metered consumption | 0 |
14 | HH | C | Estimated | Metered generation | 0 |
15 | HH | C | Estimated | Metering system specific line losses for metered generation | 0 |
16 | HH | C | Estimated | Metering system non-specific line losses for metered generation | 0 |
2 | HH | D | Actual | Unmetered consumption | 0 |
5 | HH | D | Actual | Metering system non-specific line losses for unmetered consumption | 0 |
10 | HH | D | Estimated | Unmetered consumption | 0 |
13 | HH | D | Estimated | Metering system non-specific line losses for unmetered consumption | 0 |
23 | HH | E | Actual | Metered consumption | 0 |
25 | HH | E | Actual | Metering system specific line losses for metered consumption | 0 |
26 | HH | E | Actual | Metering system non-specific line losses for metered consumption | 0 |
28 | HH | E | Estimated | Metered consumption | 0 |
30 | HH | E | Estimated | Metering system specific line losses for metered consumption | 0 |
31 | HH | E | Estimated | Metering system non-specific line losses for metered consumption | 0 |
36 | HH | E | Actual | Metered generation | 0 |
37 | HH | E | Actual | Metering system specific line losses for metered generation | 0 |
38 | HH | E | Actual | Metering system non-specific line losses for metered generation | 0 |
39 | HH | E | Estimated | Metered generation | 0 |
40 | HH | E | Estimated | Metering system specific line losses for metered generation | 0 |
41 | HH | E | Estimated | Metering system non-specific line losses for metered generation | 0 |
42 | HH | F | Actual | Metered consumption | 1 |
43 | HH | F | Actual | Metering system specific line losses for metered consumption | 1.2 |
44 | HH | F | Actual | Metering system non-specific line losses for metered consumption | 1.2 |
45 | HH | F | Estimated | Metered consumption | 1 |
46 | HH | F | Estimated | Metering system specific line losses for metered consumption | 1.2 |
47 | HH | F | Estimated | Metering system non-specific line losses for metered consumption | 1.2 |
48 | HH | F | Actual | Metered generation | 0 |
49 | HH | F | Actual | Metering system specific line losses for metered generation | 0 |
50 | HH | F | Actual | Metering system non-specific line losses for metered generation | 0 |
51 | HH | F | Estimated | Metered generation | 0 |
52 | HH | F | Estimated | Metering system specific line losses for metered generation | 0 |
53 | HH | F | Estimated | Metering system non-specific line losses for metered generation | 0 |
54 | HH | G | Actual | Metered consumption | 1 |
55 | HH | G | Actual | Metering system specific line losses for metered consumption | 1.2 |
56 | HH | G | Actual | Metering system non-specific line losses for metered consumption | 1.2 |
57 | HH | G | Estimated | Metered consumption | 1 |
58 | HH | G | Estimated | Metering system specific line losses for metered consumption | 1.2 |
59 | HH | G | Estimated | Metering system non-specific line losses for metered consumption | 1.2 |
60 | HH | G | Actual | Metered generation | 0 |
61 | HH | G | Actual | Metering system specific line losses for metered generation | 0 |
62 | HH | G | Actual | Metering system non-specific line losses for metered generation | 0 |
63 | HH | G | Estimated | Metered generation | 0 |
64 | HH | G | Estimated | Metering system specific line losses for metered generation | 0 |
65 | HH | G | Estimated | Metering system non-specific line losses for metered generation | 0 |
1 The SVA TAM Audit Sample only provides sufficient data to assess the strength of controls for SVA MC C Metering at a market level. It is not a robust method for detecting individual Metering Errors or process failures at specific Parties or Party Agents. By contrast, the CVA TAA Audit Sample focusses on the detection of individual Metering Error as a primary aim due to the significantly smaller metering population.