ISG192/06 - AUDIT OF SYSTEMS CONNECTION POINTS AND
BOUNDARY POINTS AT GRID SUPPLY POINT SITES
MEETING NAME
ISG 192
Date of meeting
28 March 2017
Owner/author
Mike Smith
Purpose of paper
Information
Classification
Public
Summary
In 2015/16 we conducted an audit of Systems Connection Points (SCPs) and
Boundary Points (BPs) at Grid Supply Point (GSP) sites. This paper presents the
results of that audit. We presented a decision paper to the PAB on 24 February
2017. We invite the ISG to note the PAB’s decisions and note that we will
present an information paper on the audit findings and the PAB’s decisions to
the SVG on 4 April 2017.
1.
Background
1.1
In May 2011, the root cause of a Trading Dispute was established as an incorrect Aggregation Rule being
applied by the Central Data Collection Agent (CDCA). At the request of the Trading Disputes Committee
(TDC), in 2011/12 we undertook an audit of Aggregation Rules against electrical site diagrams.
1.2
The scope of the review was limited to Aggregation Rules for all existing SCPs and Balancing Mechanism
(BM) Units in England and Wales and any new Aggregation Rules for SCPs and BM Units in Scotland first
registered after the start of the British Electricity Trading and Transmission Arrangements (BETTA) in 2005.
The scope was limited in Scotland as we had already reviewed the existing Aggregation Rules for SCPs and
BM Units in Scotland against commercial diagrams as part of the transition into the BETTA arrangements.
1.3
As a result of the audit of Aggregation Rules we identified six material errors with a combined materiality in
excess of £50 million, and 61 non-compliances.
1.4
We also identified the absence of any register of SCPs and/or BPs. We concluded that the existence of such a
register within ELEXON would mitigate against repeating such material errors and would assist us, the CDCA
and the Transmission Company in registering and validating Aggregation Rules appropriately going forward.
1.5
We also believe that producing such a register by auditing Site Responsibility Schedules (SRS) and electrical
site diagrams for each site will give the industry a further level of assurance that each and every connection
to the Transmission System at a site is correctly accounted for in Settlement.
2.
The audit of Systems Connection Points and Boundary Points at Grid Supply Points
2.1
The scope of the audit was limited to SCPs and BPs at GSP sites due to the known complexity of registrations
at GSPs. The aim of the audit was to confirm that all these SCPs and BPs at GSP sites are correctly captured
in Aggregation Rules.
2.2
There are currently 356 Grid Supply Points (GSPs) registered in Settlement:

201 in England and Wales; and

155 in Scotland.
ISG 192/06
Page 1 of 8
V1.0
© ELEXON 2017
ISG192/06 - AUDIT OF SYSTEMS CONNECTION POINTS AND
BOUNDARY POINTS AT GRID SUPPLY POINT SITES
2.3
There are in the region of 1,197 SCP circuits1 and 53 BP circuits at GSPs.
2.4
By March 2015, we had completed the audit of 294 GSPs (83%) including 100% of those in England, Wales
and a Scottish GSP Group.
2.5
For the remaining Scottish GSP Group, neither the Transmission Company nor ELEXON were able to gain
access to current electrical drawings or SRSs. In the absence of current electrical drawings or SRSs we
audited 10 sites for which we had the information due to registration changes in the last few years, and for
the remaining 60 sites (excluded from the 83% figure above) we used the commercial drawings made
available to us at the time of BETTA (2005). We compared these drawings from 2005 (together with those
publically available via the Licensed Distribution System Operator’s (LDSO’s) Long Term Development
Statement (LTDS)) against the currently registered Aggregation Rules. A number of anomalies/issues were
identified including two unregistered SCPs but at the time it was not possible to complete this exercise
without the assistance of the LDSO. See Table 1 below for the anomalies/issues identified at the time.
2.6
In September 2016 we received complete and current SRS list and drawings for all the GSPs in that Scottish
GSP Group. No further anomalies were identified.
2.7
However, we requested confirmation from a BSC Party that there are no unregistered BP Imports/Exports fed
from auxiliary/earthing transformers that tee off above the Settlement GSP Metering Equipment at some of
the GSPs in a Scottish GSP Group. This is to confirm any supplies (or exports) off these transformers to
Customers or generators are metered and registered for Settlements. At the time of writing this paper we are
still awaiting an answer.
Table 1: Anomalies/issues identified
1
Anomaly/Issue
Status Now
Incorrect registration (two GSPs not registered) losses for extensive Transmission System allocated
to Suppliers in a Scottish GSP Group via GSP Group
Correct Factor.
Not resolved yet.
Mismatch between BETTA (and LTDS) drawing and
Aggregation Rule at the time of audit.
Resolved.
Mismatch between BETTA drawing and Aggregation
Rule at the time of audit – BETTA drawing shows
one Super Grid Transformer (SGT) and one Grid
Transformer (GT) feeding Distribution System of
LDSO at 33kV. Errors in BETTA diagram (i.e. the
Not an issue.
The LDSO plans to install GSP Metering Equipment
by October 2017.
Trading Dispute raised. Non-settlement meter on
feeder off GSP busbar to rest of Distribution System
of LDSO, below the GSP Meter, incorrectly included
in Aggregation Rule from 18 May 2012. Now
removed from Aggregation Rule.
Current Aggregation Rule shows one GT circuit and
has done since BETTA. GT circuit (which feeds an
11kV busbar) reflected in latest diagram and current
i.e. GSP and Distribution System Connection Point (DSCP) circuits.
ISG 192/06
Page 2 of 8
V1.0
© ELEXON 2017
ISG192/06 - AUDIT OF SYSTEMS CONNECTION POINTS AND
BOUNDARY POINTS AT GRID SUPPLY POINT SITES
SGT feeds the 132kV Transmission System from a
higher voltage (275kV) and the GT feeds the
Distribution System at 11kV from 132kV).
Aggregation Rule.
Mismatch between BETTA (and LTDS) drawing and
Aggregation Rule at the time of audit.
Not an issue.
Mismatch between BETTA drawing and Aggregation
Rule at the time of audit.
Not an issue.
Two new GTs (3 and 4) added to Aggregation Rules
on 9 November 2012 and two old GTs (1 and 2)
removed on 30 October 2015. New GTs (3 and 4)
reflected in latest diagram and Aggregation Rule.
Additional GT circuit added 1 June 2011 and
reflected in latest diagram and current Aggregation
Rule.
2.8
For the sites audited, we observed considerable variance in how circuits at GSPs are registered and
inconsistency over how BPs to the Transmission System at GSPs are registered. Forty-four 'complex' sites
have been identified where circuit arrangements have the potential for future registration error when circuit
arrangements change and/or connection agreements are granted to a new party. For these ‘complex’ sites
we have produced a separate record (Attachment A) and a simplified drawing of each site (Attachment B).
2.9
Within these ‘complex’ sites, there are 25 instances of registrations that are not compliant with the letter of
the BSC (e.g. embedded BM Units or Supplier Volume Allocation (SVA) demand sites connected to a
Transmission System owner’s assets and LDSO circuits from a Transmission System owner’s busbar
registered as Distribution System Connection Points (DSCPs)). These are detailed in Section 3 of this paper.
2.10
None of these identified ‘complex’ sites impact Settlement i.e. energy is being correctly allocated, but all
introduce risk that further connection or alteration at the site might introduce error. The register and
simplified drawings are designed to mitigate against this risk.
3.
Non compliances found
3.1
The audit has identified 25 instances of registrations that are not compliant with the letter of the BSC and
introduce a risk that future changes or additions to the site might introduce errors into Settlement.
3.2
Distribution Systems Connection Point (DSCP) incorrectly registered
3.2.1 There are 14 instances of Shared GSPs2 where the 'majority user' is registered as a GSP and the 'minority
user' is registered as a DSCP.
Why are these registrations non-compliant?
3.2.2 At these 14 GSPs, the busbar is owned and operated by a Transmission System owner as part of the
Transmission System, and all LDSO circuits connect to that busbar. The 'majority user' has registered the
Metering System on the SGTs to calculate the GSP Metered Volume. The 'minority user' circuits are
individually metered and registered as a DSCP.
2
Note this is not a defined term, BSCP25 defines 'Shared GSP' as "a System (sic) Connection Point at which the Transmission System is
connected to two or more Distribution Systems. These are GSPs where either more than one LDSO is connected (via a GSP or a DSCP) and/or
where there is a LDSO connection and BP connection on the same busbar.
ISG 192/06
Page 3 of 8
V1.0
© ELEXON 2017
ISG192/06 - AUDIT OF SYSTEMS CONNECTION POINTS AND
BOUNDARY POINTS AT GRID SUPPLY POINT SITES
3.2.3 A DSCP is defined in Section X, Annex X-1 as "a Systems Connection Point at which two Distribution Systems
are connected." These circuit connections are not between Distribution Systems but are between a
Distribution System and the Transmission System and therefore as SCP circuits should also be registered as a
GSP - i.e. a true Shared GSP.
What is the Settlement Risk?
3.2.4 In all cases Settlement is correctly allocating energy. The risk is when a Transmission System owner agrees
further connection to, or undertakes work on, its assets which alter the running or metering arrangements
without the LDSO(s) appreciating the need to make any necessary amendment to their registrations 3.
What is required to make these compliant?
3.2.5 This would require 14 GSPs to be registered, all of which under BSC process require industry consultation
and Panel decision. The majority of these sites already have a Metering Dispensation for difference metering
dating to the Pooling and Settlement Agreement arrangements. It would be necessary to amend the existing
GSP Aggregation Rules, provide Aggregation Rules for the 'new' GSPs and de-register the DSCPs.
3.3
SVA Registered sites connected directly to the Transmission System.
3.3.1 There are two instances of SVA registered sites connected directly to a Transmission System owner’s assets
at GSPs. At the first of these GSPs there are two non-compliances: an SVA registered site connected directly
to a Transmission System owner’s assets and a DSCP incorrectly registered. At the second of these GSPs
there are two non-compliances: an SVA registered site connected directly to a Transmission System owner’s
assets and a small section of embedded Transmission System with a SCP not registered.
Why are these registrations non-compliant?
3.3.2 At these two GSPs, the busbar is owned and operated by a Transmission System owner as part of the
Transmission System, and the SVA registered circuits connect to that busbar. Each Customer’s connection
agreement is with the Transmission System owner. Because the circuits connect to a Transmission asset the
Metering Systems should be registered in Central Volume Allocation (CVA).
What is the Settlement Risk?
3.3.3 In all cases Settlement is correctly allocating energy. The GSP metering is on the SGT circuits and the
demand from the SVA registered circuits is part of the GSP Metered Volume. The risk is when a Transmission
System owner agrees further connection to, or undertakes work on, its assets which alter the running or
metering arrangements at the GSP.
What is required to make these compliant?
3.3.4 This would require the site registrations to move from SVA to CVA, the metering from Supplier Meter
Registration Service (SMRS) to Central Meter Registration Service (CMRS) and the registration of T_BM Units.
It would be necessary to effect an SVA to CVA transfer, amend the existing GSP Aggregation Rules to 'net
off' this demand and provide Aggregation Rules for the new BM Units.
3.4
Directly connected BM Units registered as Embedded
3.4.1 There are seven instances of BM Units connected directly to Transmission System assets at GSPs. One of
these BM Units was deregistered on 1 December 2016.
3
As evidenced at a GSP in 2014 when the Transmission System owner replaced a busbar with a circuit rather than SGT metering and a £3M
Settlement Error occurred.
ISG 192/06
Page 4 of 8
V1.0
© ELEXON 2017
ISG192/06 - AUDIT OF SYSTEMS CONNECTION POINTS AND
BOUNDARY POINTS AT GRID SUPPLY POINT SITES
Why are these registrations non-compliant?
3.4.2 At these seven GSPs, the busbar is owned and operated by a Transmission System owner and is part of the
Transmission System, and the embedded BM Units connect to that busbar. The Customers’ connection
agreements are with the Transmission System owner. All of these are Power Station demand BM Units and
there are identical Power Station connection configurations at other GSPs and these are registered
Transmission System Boundary Points and therefore as T_ BM Units.
What is the Settlement Risk?
3.4.3 In all cases Settlement is correctly allocating energy. The GSP metering is on the SGT circuits and the
embedded BM Unit Metered Volume is accounted for in the GSP Group Take Aggregation Rule. The risk is
when the Transmission System owner agrees further connections to, or undertakes work on, its assets which
alter the running or metering arrangements at the GSP.
What is required to make these compliant?
3.4.4 This would require the site registration to move from embedded to directly connected and the registration of
Transmission System BPs and T_BM Units. It would be necessary to amend the existing GSP Aggregation
Rules to 'net off' this demand from the GSP Metered Volume, provide Aggregation Rules for the new BM
Units and amend the GSP Group Take Aggregation Rules. New BSC and Transmission Company BM Unit
identifiers would need to be allocated in the BSC’s, Transmission Company’s and participant’s systems.
3.5
Embedded Transmission System with Systems Connection Points not registered.
3.5.1 There are two instances of embedded Transmission Systems with Systems Connection Points not registered
as GSPs.
a) GSP in a Scottish GSP Group
Why is this registration non-compliant?
3.5.2 A compliant GSP is a 132/33kV GSP with an 'outfeed' at 33kV via an undersea cable to an island. On the
island the substation is connected to the island’s 132kV Transmission System which connects to another
substation connecting demand and generation4. There are therefore two points at which the Distribution
System connects to a 132kV circuit operated by a Transmission System owner under a Transmission Licence.
The BSC requires that such connections be registered as SCPs (i.e. GSPs).
What is the Settlement Risk?
3.5.3 Settlement is allocating energy to the GSP Group however losses associated with the 40km of 132kV circuit
and two GTs and ancillaries making up the island’s Transmission System are being incorrectly allocated to
Suppliers through GSP Group Correction Factor rather than all BSC Parties through Transmission Loss
Multipliers. The risk is when any further connection is made to that Transmission System such as a directly
connected wind farm which unless netted from the GSP Metered Volume would cause a Settlement Error. It
is known that a proposed High Voltage Direct Current (HVDC) link will connect to this circuit and to avoid
further Settlement Error at that time will require Settlement Metering to be installed at the GSPs and those
aggregated Metered Volumes added to the GSP Group Take.
4
See simplified drawing in Attachment B.
ISG 192/06
Page 5 of 8
V1.0
© ELEXON 2017
ISG192/06 - AUDIT OF SYSTEMS CONNECTION POINTS AND
BOUNDARY POINTS AT GRID SUPPLY POINT SITES
What is required to make this compliant?
3.5.4 This would require the registration of two SCPs and the installation of Settlement Metering Equipment at the
GSPs and consultation on, and BSC Panel approval of these new GSPs. Aggregation Rules would be required
and amendment to the GSP Group Take Aggregation Rule.
3.5.5 Following the identification of this non-compliance in April 2014 and a real risk that a wind farm connection
or the connection of a HVDC link5 would cause a Settlement Error, the Transmission Company have liaised
with the Transmission System owner and the LDSO to get this correctly registered.
3.5.6 In October 2016 the LDSO confirmed it plans to upgrade existing Metering Equipment at the GSPs by June
2017 and register the Metering Equipment in Settlements as GSP Metering Systems. More recently the LDSO
confirmed this would be completed by October 2017.
b) GSP in an England and Wales GSP Group
Why is this registration non-compliant?
3.5.7 At the GSP the SGTs connect to an LDSO busbar from which an interconnector connects to a Transmission
System owner’s busbar. Connected to this busbar are further Transmission System owner assets (including
one of the SVA registered sites mentioned in Section 3.3) and further LDSO circuits6. There are therefore
multiple points at which the Distribution System connects to a 132kV busbar operated by a Transmission
System owner under a Transmission Licence. The BSC requires that such connections be registered as SCPs.
What is the Settlement Risk?
3.5.8 Settlement is allocating energy to the GSP Group however losses (which will in this case be minimal)
associated with the Transmission System are being allocated to Suppliers through GSP Group Correction
Factors rather than BSC Parties through Transmission Loss Multipliers. The risk is when any further
connection is made to that Transmission System busbar such as a directly connected wind farm which unless
netted from the GSP Metered Volume would cause a Settlement Error.
What is required to make this compliant?
3.5.9 This would require the registration of SCPs and the installation of Settlement Metering Equipment and
consultation on and BSC Panel approval of a new GSP. Aggregation Rules would be required and amendment
to the GSP Group Take Aggregation Rule.
4.
Next Steps
4.1
We have identified 44 'complex' sites where circuit arrangements have the potential for future registration
error when circuit arrangements change and/or connection agreements are granted to a new party. For each
of these we have produced a separate record and a simplified drawing of each site. These will be referred to
if future changes are made/proposed to one of these sites.
4.2
Of the 44 complex sites, in 25 instances the current registration arrangements are not compliant with the
BSC and introduce a risk that future changes or additions to the site might cause error in Settlement. The
remaining 19 sites are included in the register as they are not straight forward registrations. For example a
site which is known as one Transmission Company GSP, may supply two or more BSC GSPs. These are
5
The connection of this HVDC link will be a connection between Transmission Licensee owned assets and as such will require no BSC advice or
registration.
6
See simplified drawing in Attachment B.
ISG 192/06
Page 6 of 8
V1.0
© ELEXON 2017
ISG192/06 - AUDIT OF SYSTEMS CONNECTION POINTS AND
BOUNDARY POINTS AT GRID SUPPLY POINT SITES
examples of 'complex' sites where it is necessary to consider the current registration arrangements before
any amendment.
4.3
Although there are registration non-compliances, all but two of these non-compliances have no material
effect under the BSC and there is currently no impact due to them on BSC Parties i.e. Settlement is correctly
allocating energy, even though the way the registration has been done doesn’t meet the letter of the BSC.
4.4
To date no decision has been taken to enforce correction of any of these non-material erroneous
registrations most of which have been in place since the start of the Trading Arrangements in 2001.
Regularising these registrations means costs for affected BSC Parties and Customers, and such change
creates a small risk of introducing Settlement Error as a consequence of making these corrections.
4.5
Not addressing these non-compliances leaves the risk that further connection or alteration at the site might
introduce error. The register and simplified drawings are to mitigate against this risk and the Transmission
Company have already stated that they have found them helpful in clarifying registration requirements for
changes at the identified sites.
4.6
In February 2017 (PAB193B/20) ELEXON consulted the Performance Assurance Board (PAB) on whether
there is appetite to enforce correction of the identified registration non-compliances or to manage them using
the ‘complex’ sites list and drawings. Section 6 of this paper details the recommendations we made and the
PAB’s decisions.
4.7
ELEXON also recommended to the PAB that we note the audit findings and the PAB’s decisions on that paper
to the ISG and the Supplier Volume Allocation Group (SVG).
5.
Actions arising
5.1
The audit and the production of simplified electrical and metering diagrams has reinforced some of the
shortcomings with the current BSC Procedure (BSCP) 757 and shown the opportunity to update it to include
simplified drawings and example Aggregation Rules indicating how they might be prepared by the Registrant
for each scenario.
5.2
ELEXON recently introduced new guidance for BSCP75 called ‘Constructing Aggregation Rules – Central
Volume Allocation’. Action completed.
5.3
ELEXON and the Transmission Company have committed to maintain the register of SCPs and a joint record
of 'complex' sites, together with simplified drawings. Such records are only as good as the information
provided and the completion and updating of the register is dependent on the co-operation of all three
onshore Transmission System Licensees and all LDSOs. Action ongoing.
5.4
The audit of a Scottish GSP Group has identified two non-compliances. These are outstanding, however in
October 2016 the LDSO proposed installing/upgrading Metering Equipment at the GSPs by June 2017. The
LDSO more recently confirmed it would install Metering Equipment at the GSPs by October 2017. We will
keep chasing the LDSO for updates and report back to the PAB, ISG and SVG if the LDSO does not install
GSP Metering Equipment by October 2017. Action ongoing.
5.5
We requested confirmation from a BSC Party that there are no unregistered BP Imports/Exports fed from
auxiliary/earthing transformers that tee off above the Settlement GSP Metering Equipment at some of the
GSPs in a Scottish GSP Group. This is to confirm any supplies (or exports) off these transformers to
Customers or generators are metered and registered for Settlements. At the time of writing this paper we are
still awaiting an answer. Action ongoing.
7
BSCP75 - Registration of Meter Aggregation Rules for Volume Allocation Units
ISG 192/06
Page 7 of 8
V1.0
© ELEXON 2017
ISG192/06 - AUDIT OF SYSTEMS CONNECTION POINTS AND
BOUNDARY POINTS AT GRID SUPPLY POINT SITES
6.
PAB decisions
6.1
We presented a decision paper to the PAB on 24 February 2017. The PAB:
a)
AGREED that ELEXON should not enforce correction of the registration non-compliances but manage
them;
b)
AGREED that ELEXON continue to maintain the register of SCPs and BPs at GSP sites;
c)
AGREED that ELEXON reports back to the PAB a BSC Party does not install GSP Metering Equipment at
two sites by October 2017;
d)
AGREED that ELEXON reports back to the PAB if a BSC Party confirms there are BP flows off auxiliary
transformers at GSP sites in a GSP Group and these are not accounted for in Settlements; and
e)
NOTED that ELEXON will present an information paper on the audit findings and the PAB’s decisions on
this paper to the ISG on 28 March 2017 and the SVG on 4 April 2017.
6.2
In addition, the PAB noted that in relation to recommendation c) the LDSO for a Scottish GSP Group recently
confirmed that it intends to install GSP Metering Equipment at the two sites by October 2017, not June 2017,
as originally stated in the PAB paper.
7.
Recommendations
7.1
We invite you to:
a)
NOTE the results of the audit of SCPs and BPs at GSP sites;
b)
NOTE the PAB’s decisions on the decision paper we presented to it on 24 February 2017;
c)
NOTE that ELEXON will report back to the ISG if a BSC Party does not install GSP Metering Equipment at
two sites by October 2017;
d)
NOTE that ELEXON will report back to the ISG if a BSC Party confirms there are BP flows off auxiliary
transformers at GSP sites in a GSP Group and these are not accounted for in Settlements; and
e)
NOTE that ELEXON will present an information paper on the audit findings and the PAB’s decisions to
the SVG on 4 April 2017.
Attachments
Attachment A (CONFIDENTIAL) – Listing of complex sites
Attachment B (CONFIDENTIAL) – Complex GSP Simplified drawings
For more information, please contact:
Mike Smith, Metering Analyst
[email protected]
020 7380 4033
ISG 192/06
Page 8 of 8
V1.0
© ELEXON 2017