Download 1 Confirmed Action Notes of the DG Technical Forum meeting

DG Technical Forum 3 - 021213
Confirmed Action Notes of the DG Technical Forum meeting
December 02 2013
Name
Martin Lee
ML
Tim Russell
TR
Trung Tran
TT
Bob Weaver
BW
Kevin Burt
KB
Lee Mason
LM
Chris Smith
CS
Chris Marsland
CM
Steven Robertson SR
David Spillett
DS
Glen Hodges
GH
James Hoare
JH
Paul Black
PB
John Moore
JM
Nick Yenkyn
NY
Apologies:
Ian Povey
David Clare
Andy Hood
Held at EIC commencing 10:30
Attendees:
Company
Scottish & Southern Energy
REA
Scottish & Southern Energy (alternate for Matthew Gordon)
Powercon
UK Power Networks
DNO Consulting
RWE
AMPS
ENW
Energy Networks Association
Northern Powergrid
BRE National Solar Centre
Scottish Power
Windcrop/RED
West Coast Energy
Electricity North West
VBC Associates
Western Power Distribution
1. Welcome to EIC and housekeeping
ML welcomed members to this meeting of the DG Technical Forum. DS explained
housekeeping/emergency arrangements. Each member introduced themselves to the
group. Housekeeping/emergency arrangements were provided. Apologies were noted.
2. Revised Terms of Reference and approval
DS confirmed that the revised terms of reference have now been posted to the ENA DG
Technical Forum website
- http://www.energynetworks.org/electricity/engineering/distributed-generation/ena-dg-tec
hnical-forum.html
3. Time keeping within meeting
ML reminded members of the importance of trying to keep to a reasonable time for
discussion of individual item; however it was important to also afford enough time for
debate and resolution.
4. Agree minutes from previous meeting held on 24 October 2013
The members agreed that the notes of the previous meeting were accurate. They asked
that these be added to the ENA DG Technical Forum website.
Action: DS
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DG Technical Forum 3 - 021213
5. DNO fails to comply with the recommendations of G59 they would be in breach of
their licence conditions.
LM confirmed that this question was raised over one year ago and in the interim the
question has subsequently been resolved. A short debate then took place over the
connection of VTs and what side of a CB should they be connected. It was agreed that the
DNOs would confirm and feedback on their respective positions.
Action: All DNOs
6.
Report back on actions from previous meeting
At the meeting in September the DNOs were requested to respond to the points below in
the same format as the Scottish Power response. They subsequently supplied their
respective response by the use of a standard template and each DNO in turn reported
back on its position with respect to each issue.
The individual DNO responses to each point are attached as an appendix 1 to these
minutes. Any follow up action is listed against each item below.
6.1.
Voltage control / Voltage rise issues including the use of different voltage
control strategies at the generator level (fixed power factor, fixed voltage
target, variable voltage target etc)
ML confirmed SHEPD will host a learning event to discuss with other DNOs the use of
‘voltage control (PV mode)’ to connect DG in their area.
Action: ML / TT
TR suggested the Forum should return to this issue at the April meeting following the
workshop which has been planned for February/March 2014.
Action: ML/DS
6.2.
Number of circuit breakers required for a generator connection
It was agreed that actual question could be closed off as there was not one DNO who
was actually insisting on the use of two CBs.
Where DNOs allowed their circuit breaker to protect a customer installation up to a
limit of a set distance from their circuit breaker they would give the reasoning behind
setting that particular distance.
Action: All DNOs
During the discussion the issue of composite boards in S/stns was raised and it was
apparent that there appeared to be differing DNO policies on the use of shared boards
for DG Installations and also arrangements for access into S/stns.
It was agreed that the DNOs would feedback what their respective policies are for use
of Composite boards at the next meeting in April.
Action: All DNOs
6.3.
Differences in anti-islanding requirements between DNOs
All DNOs provided detail on their anti-islanding requirements, this information can be
found in appendix 1.
ML informed the Forum that current work ongoing via National Grid WG will have a
possible effect on DNO and Generator protection policies in particular Loss of Mains
protection particularly RoCoF. It was agreed that the Forum would return to this
issue following the publication of the NG proposals/policy. This is expected early
2014.
Action: DS/ML
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DG Technical Forum 3 - 021213
6.4.
Sub-station housing requirements
David Spillett reported back that this work will need to be delivered by the ENA and not
the EATL Strategic Technology Programme. DS will raise the matter with the ENA
Electricity Networks & Futures Group (ENFG) requesting that they consider
establishing a task group to develop a set of generic functional requirements for DG
sub-station housing that demonstrate to generators some degree of DNO
consistency. Health Safety & Environmental factors are paramount in any work to
develop substation housing policy.
Action: DS/ML
6.5.
Scada requirements for DNO monitoring of generation output
All DNOs reported on their requirements for generator output monitoring see appendix
1. Following a discussion on this issue it was evident that four DNOs had very similar
policies and two DNOs differed. It was agreed that the two DNOs would revisit their
policy and report back at the next meeting.
Action: PB/KB
ML agreed to review the European network code ‘RfG’ to determine its impact on
Scada requirements.
Action: ML
Members question the requirements with respect to fixed line telephony.
DNOs agreed to check on this and report back to this group.
Action: All DNOs
6.6
Facilitation of non-firm / actively managed connections as part of business as
usual rather than as part of a RPZ or low carbon network fund project.
The DNOs all reported abck and all agreed that there are no technical issues that
prevent the use of NfC or ANM.The DNOs are currently trialling projects that are
looking at Non-firm Connections (NfC) or Active Network Management (ANM.).
There is no “off the shelf” or BAU product available but they will be in the next few
years once the various LCNF projects deliver.
It was suggested that a further update should be provided by the DNOs in 6-12 months
time. TR reported that the “commercial group” was looking at information provision
and commercial aspects of non firm agreements.
7.
WPD LCNF LV Network Templates Project
As WPD were not present at the meeting it was agreed that this agenda item would be
carried forward to the next meeting in April 2014.
Action: AH/DS
8.
Neutral Voltage Displacement
This issue was raised at the last meeting by CM during the anti islanding discussions
as he thought NVD was part of the anti islanding protection requirement..
High voltage networks normally only have one point at which energy is fed into the
network. They are earthed at this point and earth fault protection is done using over
current protection systems connected to be sensitive to earth faults but not phase to
phase faults.
Where a network can be energised from more than one point but where the system is
not to be earthed then conventional earth fault protection does not work.
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DG Technical Forum 3 - 021213
NVD protection is normally fitted at the location where a network can be energised
from an alternative point from the normal system earth and does not require the system
to be earthed at the location it is fitted.
Distribution Network Operators (DNOs) use NVD protection quite often particularly in
parallel transformer situations where a higher voltage line fault can be back energised
via the other circuit and the lower voltage bus bar.
Generators connected to a DNOs system can potentially provide a back feed to the
network and the DNO may in some circumstances require the installation of NVD
protection.
The rules for using NVD protection were worked out during the development of G59/2
which was published in 2010 and they have remained unchanged in the latest revision
of G59/3 published in September 2013.
These take account of the chances of a generator being able to remain connected to
the system should a fault occur which disconnects the normal source of supply to a
system.
Where a generator may balance the network load and where the generators control
system can control the voltage then NVD may be required. In most cases NVD
protection is not required. The DNO will study their system and make a decision on
the requirement for NVD protection as part of the process of designing a connection,
prior to making a connection offer to a developer.
Following some clarification by ML it was agreed that the requirements for use of NVD
are detailed in ERG 59.
This matter is now closed.
9.
DG Connection Guides – Update
DS informed the forum that the draft Guides are now ready to proceed to next phase ie
public consultation. Agreement will be given by the DCRP at its meeting on 5/12/13
and the draft guides will be issued w/c 9 December for a period of 4-6 weeks
consultation.
10.
AOB
Harmonic Analysis
PB raised the issue of Harmonic analysis (System Analysis v N-1) and it was agreed
that this should be added as an agenda item for the next meeting.
DNOs to report back at the next meeting
Action: All DNOs/DS
Policies on Interface Box Standards
CS raised the issue of Interface Boxes and how the DNOs apply differing policies.
ML suggested CS should prepare a question for circulation to DNOs for feedback at
the next meeting.
Action: CS
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DG Technical Forum 3 - 021213
Tim Russell Retirement
TR is due to retire and the forum is seeking a suitable DG replacement.
JH suggested that the STA and the REA discuss this outside the meeting. In the
meantime can ENA continue to email TR with all the information papers etc.
Action: JH/TR
Load Control Devices.
DS raised the matter of LCDs and the use of these products on DNO networks as a
result of enquiries by manufacturers. It was suggested that this be discussed at the
next meeting and the DNOs will feedback individual DNO Policy.
Action: DNOs
11.
Date of next meeting 9 April 2013
Members noted the date of the next meeting of this group. Members agreed to
complete the actions above by mid-March 2014.
Action: DS
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DG Technical Forum 3 - 021213
Ongoing Actions.
1
2
3
4
DNO target levels which may be different to Action: ML
statutory voltage limits
Status of ERs G83 & G59
DNO fails to comply with the recommendations
of G59 they would be in breach of their licence
conditions.
Clarification of connection of VTs and what side of a Action: DNOs
CB should they be connected. It was agreed that the
DNOs would confirm and feedback on their
respective positions.
Closed
Closed
Voltage control / Voltage rise issues including
the use of different voltage control strategies at
the generator level (fixed power factor, fixed
voltage target, variable voltage target etc)
ML confirmed SHEPD will host a learning event to Action: ML / TT
discuss with other DNOs the use of ‘voltage control
(PV mode)’ to connect DG in their area.
TR suggested the Forum should return to this issue Action: DS
at the April meeting following the workshop which
has been planned for February/March 2014.
5
Number of circuit breakers required for a
generator connection
It was agreed that actual question could be closed Action: All DNOs Closed
off as there was not one DNO who was actually
insisting on the use of two CBs.
Where DNOs allowed their circuit breaker to protect Action: All DNOs
a customer installation up to a limit of a set distance
from their circuit breaker they would give the
reasoning behind setting that particular distance.
6
Composite Boards
During the discussions the issue of composite
boards in S/stns was raised and it was apparent that
there appeared to be differing DNO policies on the
use of shared boards for DG Installations and also
arrangements for access into S/stns.
It was agreed that the DNOs would feedback what All DNOs
their respective policies are for use of Composite
boards at the next meeting in April.
7
Differences in anti-islanding requirements
between DNOs
All DNOs provided detail on their anti-islanding Action: All DNOs Closed
requirements; this information can be found in
appendix 1.
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DG Technical Forum 3 - 021213
ML informed the Forum that current work ongoing
via National Grid WG will have a possible effect on
DNO and Generator protection policies in particular Action: ML
Loss of Mains protection particularly RoCoF. It was
agreed that the Forum would return to this issue
following the publication of the NG proposals/policy.
This is expected early 2014.
8
Sub-station housing requirements
DS reported back that this work will need to be Action: DS
delivered by the ENA and not the EATL Strategic
Technology Programme. DS will raise the matter
with the ENA Electricity Networks & Futures Group
(ENFG) requesting that they consider establishing a
task group to develop a set of generic functional
requirements for DG sub-station housing that
demonstrate to generators some degree of DNO
consistency. Health Safety & Environmental factors
are paramount in any work to develop substation
housing policy.
9
Scada requirements for DNO monitoring of
generation output
All DNOs reported on their requirements for Action: PB/KB
generator output monitoring. Following a discussion
on this issue it was evident that four DNOs had very
similar policies and two DNOs differed. It was
agreed that the two DNOs would revisit their policy
and report back at the next meeting.
ML agreed to review the European network code Action: ML
‘RfG’ to determine its impact on Scada
requirements.
Members question the requirements with respect to Action: DNOs
fixed line telephony. DNOs agreed to check on this
and report back to this group.
10
Facilitation of non-firm / actively managed
connections as part of business as usual rather
than as part of a RPZ or low carbon network
fund project.
Action: DNOs
The DNOs all reported back and all agreed that
there are no technical issues that prevent the use of
NfC or ANM. The DNOs are currently trialling
projects that are looking at Non-firm Connections
(NfC) or Active Network Management (ANM.).
There is no “off the shelf” or BAU product available
but they will be in the next few years once the
various LCNF projects deliver.
7
Closed
DG Technical Forum 3 - 021213
Action: ML/DS
It was suggested that a further update should be
provided by the DNOs in 6-12 months’ time. TR
reported that the “commercial group” was looking at
information provision and commercial aspects of
non-firm agreements.
11
12
13
WPD LCNF LV Network Templates Project
Action: AH
Update by AH
Neutral Voltage Displacement
Action: ML
DG Connection Guides – Update
DS informed the forum that the draft Guides are now Action: DS
ready to proceed to next phase ie
public
consultation. Agreement will be given by the DCRP
at its meeting on 5/12/13 and the draft guides will be
issued w/c 9 December for a period of 4-6 weeks
consultation. Update at next meeting.
14
Harmonic Analysis
PB raised the issue of Harmonic analysis (System Action: DNOs
Analysis v N-1) and it was agreed that this should be
added as an agenda item for the next meeting.
DNOs to report back at the next meeting
15
Policies on Interface Box Standards
CS raised the issue of Interface Boxes and how the Action:
CS/DMOs
DNOs apply differing policies.
ML suggested CS should prepare a question for
circulation to DNOs for feedback at the next
meeting.
16
Load Control Devices.
DS raised the matter of LCDs and the use of these Action: All DNOs
products on DNO networks as a result of enquiries
by manufacturers. It was suggested that this be
discussed at the next meeting and the DNOs will
feedback individual DNO Policy.
8
Ongoing
Closed
th
DG Technical Issues Forum – 24 October 2013
ENWL Response to Actions
Minute
4
Technical Issue
Voltage control /
Voltage rise issues
including the use of
different voltage control
strategies at the
generator level (fixed
power factor, fixed
voltage target, variable,
voltage target etc)
LV
ENWL would consider/study a DG
connection operating in PQ mode with a
fixed pf in the range 0.95 lag to 0.95 lead
and would offer connection on this basis.
The vast majority of DG connected to
ENWL’s network operates in PQ mode
however, we recognise that there may be
benefits in operating in PV mode and we
would seek to work with the customer to
understand the specific connection
arrangements. ENWL would also
consider utilising other technologies ie
SVCs, voltage regulators etc..
HV
ENWL would consider/study a DG connection operating in
PQ mode with a fixed pf in the range 0.95 lag to 0.95 lead
and would offer connection on this basis. The vast majority of
DG connected to ENWL’s network operates in PQ mode
however, we recognise that there may be benefits in
operating in PV mode and we would seek to work with the
customer to understand the specific connection
arrangements. ENWL would also consider utilising other
technologies ie SVCs, voltage regulators etc..
EHV
ENWL would consider/study a DG
connection operating in PQ mode with a
pf range 0.95 lag to 0.95 lead and would
offer connection on this basis. The pf
range may be restricted if that would
allow a connection without reinforcement.
The vast majority of DG connected to
ENWL’s network operates in PQ mode
however, we recognise that there may be
benefits in operating in PV mode and we
would seek to work with the customer to
understand the specific connection
arrangements. ENWL would also
consider utilising other technologies ie
SVCs, voltage regulators etc..
No mandatory requirement for a series CB at the connection No mandatory requirement for a series
point. ENWL owned circuit breaker can be tripped by the DG. CB at the connection point. ENWL owned
circuit breaker can be tripped by the DG.
6
Number of circuit
breakers required for a
generator connection
The DG shall provide as part of their
installation a generator CB.
9
Differences in antiislanding requirements
between DNOs
ENWL adhere to the principles laid out in G59
para10.3.7.ENWL usually require RoCoF relay as the
primary G59 protect but is not prescriptive in respect of
secondary protection.
10
Sub-station housing
requirements
ENWL adhere to the principles laid out in
G59 para10.3.7.ENWL usually require
RoCoF relay as the primary G59 protect
but is not prescriptive in respect of
secondary protection.
11.1
SCADA requirements
for DNO monitoring of
generation output
All DG with export capacity greater than
200kW shall be controlled by a CB that
can be operated by the ENWL SCADA
system. The following network data
measured at the CB shall be provided to
the SCADA system:
• Directional real and reactive
power flow
• Directional current flow
• Network voltage
• Circuit breaker status
All DG with export capacity greater than 200kW shall be
controlled by a CB that can be operated by the ENWL
SCADA system. The following network data measured at the
CB shall be provided to the SCADA system:
• Directional real and reactive power flow
• Directional current flow
• Network voltage
• Circuit breaker status
All DG with export capacity greater than
200kW shall be controlled by a CB that
can be operated by the ENWL SCADA
system. The following network data
measured at the CB shall be provided to
the SCADA system:
• Directional real and reactive
power flow
• Directional current flow
• Network voltage
• Circuit breaker status
11.2
Power (Battery or
alternative LV supplies)
back-up requirements
Incorporation of the LV
(battery charger etc.)
supply quote into the
overall EHV quote
Where the connection is at 6.6kV or higher voltage and both
ENWL and the Generator require a DC supply for protection or
control purposes, the parties my agree that only one battery is
necessary, for the purposes of both. In that case, ENWL will
provide the necessary battery and charger and be responsible
for their monitoring and maintenance. The low voltage (240V)
supply to the charger will be derived from the permanent
wiring installation within the substation. It is normally expected
that this supply will be provided from the Generator’s electrical
Where the connection is at 6.6kV or higher
voltage and both ENWL and the
Generator require a DC supply for
protection or control purposes, the parties
my agree that only one battery is
necessary, for the purposes of both. In
that case, ENWL will provide the
necessary battery and charger and be
responsible for their monitoring and
ENWL adhere to the principles laid out in
G59 para10.3.7.ENWL usually require
RoCoF relay as the primary G59 protect
but is not prescriptive in respect of
secondary protection.
Additional Commentary
ENWL must comply with GSOP standards therefore
standard connection quotations are based on DG
operating in PQ mode. Alternative connection
arrangements would generally be considered by
undertaking a feasibility study.
Note: Large DG (>100MW) are subject to the
requirements of the Grid Code which does specific a
voltage performance for the generation.
ENWL will not allow its CB to be used for the
purposes of synchronising generator units with the
network. ENWL will carry out a risk assessment on
the duty on the its CB and the protection and where
this is unduely arduous, ENWL may require the DG to
install a series CB that would be controlled by the
DG’s protection.
ENWL are will to contribute to a working group to
consider a generic national standard for substation
enclosures.
th
DG Technical Issues Forum – 24 October 2013
ENWL Response to Actions
Minute
Technical Issue
12
Facilitation of nonfirm/actively managed
connections - Business
as Usual
It was agreed that the
DNOs would identify
any technical reasons
as to why they cannot
use managed
connections and would
report findings back at
next meeting.
LV
HV
EHV
Additional Commentary
installation. In any particular case, all these responsibilities maintenance. The low voltage (240V)
shall be set out in the Site Responsibility Schedule.
supply to the charger will be derived from
the permanent wiring installation within the
Note: ENWL West may provide a fused supply from the substation. It is normally expected that
battery at the request of the Generator, provided this supply will be provided from the
that DC circuits are not extended outside the site Generator’s electrical installation. In any
boundary, that the drain imposed on the battery by particular case, all these responsibilities
Generator’s equipment is fixed and specifically shall be set out in the Site Responsibility
agreed, and that the battery charger is fitted with an Schedule.
alarm connected to the Electricity North West’
telecontrol system (where connected). However Note: ENWL West may provide a fused
Electricity North West will recover any costs
supply from the battery at the
associated with a failure of the battery charger as a
request of the Generator,
result of any failure on the Generator’s system.
provided that DC circuits are
not extended outside the site
boundary, that the drain
imposed on the battery by
Generator’s equipment is fixed
and specifically agreed, and
that the battery charger is fitted
with an alarm connected to the
Electricity
North
West’
telecontrol system (where
connected).
However
Electricity North West will
recover any costs associated
with a failure of the battery
charger as a result of any
failure on the Generator’s
system.
ENWL will consider non-firm/actively managed
connections at all voltage levels.
th
DG Technical Issues Forum – 24 October 2013
ENWL Response to Actions
DG Technical Issues Forum Meeting #3 – 2 December 2013
th
Northern Powergrid Response to Actions assigned 27 August 2013
Minute
4
6
Technical Issue
Voltage control /
Voltage rise issues
including the use of
different voltage control
strategies at the
generator level (fixed
power factor, fixed
voltage target, variable,
voltage target etc)
Number of circuit
breakers required for a
generator connection
LV
Generator to operate in the range 0.95
lag to unity
HV
Generator required to have a performance range of 0.95 lag
to unity, with NPg determining a set pf within that range.
The customer’s LV protection is always
expected to be within the locality of the
metering fuse / CB.
Where there are limitations in the protection capability on
metering CB, or the complexity of the customer’s installation
requires further points of protection, it may be necessary for
the customer to install a CB in series with the metering CB.
9
Differences in antiislanding requirements
between DNOs
10
Sub-station housing
requirements
See commentary
11.1
SCADA requirements
for DNO monitoring of
generation output
None
11.2
Power (Battery or
alternative LV supplies)
back-up requirements
Incorporation of the LV
(battery charger etc.)
supply quote into the
overall EHV quote
EHV
Generator required to have a
performance range of 0.95 lag to unity,
with NPg determining a set pf within that
range.
Medium embedded power stations will be
required to operate in PV mode across
the range 0.95 lead to 0.95 lag unless
there is a technical limitation on the DNO
network.
The customer’s protection will be fitted to
the metering circuit breaker via an
interface panel, thus negating the need
for the customer to install a back-to-back
CB in most circumstances. This
protection can include a local
transformer, or a long unit protected
cable.
The assessment for anti – islanding is based on the
An intertrip signal is provided
minimum demand in the protection zone. The risk analysis is
carried out if the minimum load requirements are not met and
the risk of generators islanding the protection zone less than
once in 40 years is deemed to be acceptable. Otherwise an
intertrip signal is required.
See commentary
While we don’t readily use GRP type
enclosures at EHV sites, NPG would be
willing to accept its use providing all
adequate risk assessments and building
requirements are met.
Limited SCADA required at HV sites, but with no control
facilities.
Customer to provide an LV supply to the metering s/s. No
additional backup required
Full SCADA is required at all EHV s/s.
Monitoring only takes place at point of
supply. Any NGET requirements for
operational metering are currently
provided directly from the customer to
NGET.
For single circuit connections to a
generator, they will provide the normal
LV supply to the metering s/s. A backup
LV supply will be obtained from the local
11kV network. A connection from an
existing LV network is not permitted to
avoid transfer of earth rise potential into
the LV system for an EHV fault.
For double circuit connections, the
generator will provide the main and
Additional Commentary
Only Medium embedded power stations are allowed
to operate in PV mode, to meet the requirements of
the grid code.
All other generation will operate in PQ mode.
NPg will not install a joint switchboard. Therefore
there may be occasions when a back-to-back CB is
installed by the customer to make the connection on
their switchboard.
NPg will not allow a generator to be synchronised
across the metering CB. Therefore, if the site is going
to operate in island mode it may be necessary to
provide a back-to-back CB to avoid making the site
dead to re-synchronise following an event.
The customer is still required to fit standard G.59
protection in all scenarios
The requirements for a particular type of enclosure to
be established will be based upon a risk assessment
of the site location, including surrounding, known
trespass issues, children commuter routes as
described in the Electricity Councils publication
entitled Child Trespassers in Electricity Substations
(1986) which will help determine the most suitable
enclosure. In general NPG allow the use of GRP
installations across the full range of substation
buildings providing the requirements of the risk
assessment are met.
It is anticipated that the SCADA requirements for HV
connected generation will increase in the future.
DG Technical Issues Forum Meeting #3 – 2 December 2013
th
Northern Powergrid Response to Actions assigned 27 August 2013
Minute
Technical Issue
12
Facilitation of nonfirm/actively managed
connections - Business
as Usual
It was agreed that the
DNOs would identify
any technical reasons
as to why they cannot
use managed
connections and would
report findings back at
next meeting.
LV
HV
EHV
backup LV supply.
Additional Commentary
DG Technical Issues Forum Meeting #3 – 2 December 2013
th
Northern Powergrid Response to Actions assigned 27 August 2013
DG Technical Issues Forum Meeting #3 – 2 December 2013
th
SP Energy Networks – Response to Actions assigned 27 August 2013
Minute
4
Technical Issue
Voltage control /
Voltage rise issues
including the use of
different voltage control
strategies at the
generator level (fixed
power factor, fixed
voltage target, variable,
voltage target etc)
LV
Not applicable
HV
The voltage rise associated with HV or LV connected
generation needs careful consideration. During light system
loading the generation can increase the HV network voltage
above that which would cause LV voltages to exceed that
declared to customers.
EHV
Generation at 132kV (SPM) and 33kV is
considered on a case-by-case basis and
approved by the Design Authority.
The HV network voltage remote from a primary substation
will be largely determined by the reactive power (kVAr) flow
and especially on overhead lines with higher a X/R ratio.
Flow towards the primary will raise the voltage and flow from
the primary will reduce the voltage. If an embedded
generator were required to hold the voltage constant (so
called PV mode) then this would require them to produce
and absorb relatively significant amounts of reactive power.
They are therefore normally instructed, via their Connection
Agreement, to operate with a fixed power factor (so-called
PQ mode).
Additional Commentary
SPEN working within scope of LCNF Tier 2 Project ARC to determine ability to trial voltage based
constraints via tripping schemes at all voltage levels.
SPEN continue discussion with turbine manufacturers
where the opportunity arises to appreciate the PV
capability. On some of the more popular machines, it
is noted that the capabilities of some of the more
common turbines aren’t as extensive as the larger
units. We are seeking to roll out a trial where we can
find appropriate sites.
System studies are used to determine the required power
factor for a particular generator connection (the lowest power
factor allowed is usually 0.95). The aim is to ensure that
there is less than 6% voltage step change if the generator
connection is disconnected, even at full output.
6
Number of circuit
breakers required for a
generator connection
N/A
SPEN facilitate the use of HV AVRs where appropriate.
These are proposed / installed at the enabling point on the
HV circuit for each application.
When assessing connection methods for individual sites, the
definition of that equipment “which cannot be otherwise
protected” arises. The reasonableness of what equipment
will be protected by the Company systems as they “cannot
be otherwise protected” may be open to debate or challenge
and is dependent on the specific circumstances for that site.
However, it should be stressed at this point that, where the
customers installation has significant equipment at the
supply voltage, the Company will require a “sequential”
protective device (e.g. circuit breaker), owned and operated
by the customer, to be established as close as practicable to
the supply protective device.
As per HV plus
With respect the bullet point
“- Short section of cable (<=100m),
transformer and lower voltage cable tails
where the customers installation is
immediately adjacent to the source
(substation etc), i.e. there is a common
boundary“, it should also be noted that
historically this can apply to 33kV
connected customers who immediately
transform down to lower voltages
immediately after the point of connection
as well as 11kV connected customers
The individual connection conditions for the project should be with primary distribution systems at LV.
taken into consideration when assessing the requirements
While there are existing installations of
for the customer installation. The extent of the customer
this configuration, current practice should
be to minimise the protection overlap by
installation effectively protected by the „Statutory Breaker‟
should be minimised but is unreasonable to expect that it can terminating on incomers to a 33kV
be totally eliminated. The phraseology of ‘protection’ refers to switchboard with the transformers
protected by dedicated circuit breakers
the function as opposed to the equipment. It does not
simplistically refer to the protection systems associated with
the interface equipment (Statutory Breaker) but the duty of
the device itself. The duty required of the interface device is
to prevent an excess of energy entering the customer’s
132kV connections in SPD are Transmission
connections.
SPEN do not believe the NGET/DNO interface is an
appropriate example to base discussion on in this
instance. Dual redundant BBZ schemes are
prevalent on these sites with the plant confined to
existing substation boundaries, notably for
transmission connections, the CUSC permits
customer connections at busbar clamps’ (or
appropriate gas-zone barriers for GIS equipment) of
the source connecting substation. This results in the
customer’s circuit breaker protecting the outgoing
circuit in its entirety and the Company equipment
protecting busbars, connections and ancillary
equipment. This option requires careful consideration
from an operation perspective in terms of shared site
responsibility / access.
Where the interface is with an IDNO or other DNO,
the overall connection should be designed as if all
assets are within the ownership of this Company and
the interface, asset ownership and liabilities are
contractual arrangements. In consequence, the
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Minute
Technical Issue
LV
HV
system and not the primary protection of the customer’s
equipment. Therefore, the provision by the customer of
protection CTs to be located within the statutory circuit
breaker for the purposes of initiating a disconnection of a
fault on the customers equipment by the statutory breaker is
not acceptable. Customer protection CTs contained in the
statutory breaker may be acceptable only when the
protection scheme is associated with the protection of
minimised overlap equipment.
EHV
Additional Commentary
boundary and protection issues discussed above are
not required.
It is not possible to fully eliminate the need to provide a
degree of protection for interface equipment and therefore, it
becomes an assessment of what equipment is considered
reasonable. The following list is not exhaustive but provides
guidance of what can reasonably be considered as
acceptable.
- Short section of bus-bar for joint ownership substations.
Higher voltage installations (>11kV) should preferably have
busbar protection installed to ensure rapid disconnection of
bus-bar faults.
Larger installations at 11kV should also consider similar
protection.
- Short section of cable (<=100m) where the customers
installation is immediately adjacent to the source (substation
etc), i.e. there is a common boundary.
- Short section of cable (<=100m), transformer and lower
voltage cable tails where the customers installation is
immediately adjacent to the source (substation etc), i.e. there
is a common boundary.
9
Differences in antiislanding requirements
between DNOs
<= 200kW LV connected G59/2
generation shall have dual loss of mains
>200kW Larger LV connected
generators can be accommodated with
the actual connection at LV but the
interface protection being established at
HV. This therefore does not automatically
require HV connections when interface
protection is required
10
Sub-station housing
requirements
Not Applicable
In all other cases, the customer installation must provide a
sequential circuit breaker to perform the duty of protection for
the private equipment and installation.
<1MW – no intertrip required
>1MW, <=2MW Intertrip desirable but applied only if pilot
cable or fibre optic is being established for metering and
control purposes
Back-up G59 relay installed on metering
circuit breaker with graded settings.
Intertripping facilitated on case by case
basis
>2MW, <=5MW Full intertrip functionality via pilot cable or
fibre optic if economic and practical
>2MW, <=5MW (Connected at Primary Substation) Full
intertrip functionality via pilot cable or fibre optic or crosstripping within substation
>5MW Full intertrip functionality via pilot cable or fibre optic
The SP standard for DG substations where interface
protection is required, is a brick built substation developed
from those utilised with unit protection – from a cost
perspective, we recognise that this solution is too onerous
and a barrier to a cost effective grid connection. The indoor
Not an issue – generally via customer
built substation or container solution
provided by SPEN. DG group provide
standard substation layouts for
customers to tender civil works on.
SPEN have recently changed their supplier for
primary and 33kV substation housing to a GRP
manufacturer. Costs associated with these units are
more favourable to customers (previously smallest
container was ~£90k). DG group seek a waiver of
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Technical Issue
LV
HV
environment is required to house the batteries, charger and
protection panel.
EHV
Additional Commentary
local housekeeping alarms via SCADA for sites
<1MW to facilitate use by customers.
To progress this, we are working with the
customer/developer to meet a suite of functional specification
requirements to provide a GRP solution which meets the
‘indoor environment’ solution – to this end we are
progressing provided that it is signed off against a
professional civil engineers letter (and associated
professional indemnity and liability insurance policies). In
line with our subsequent 25/40 year O&M responsibility to
the site we cannot carry an associated risk against a design
we haven’t specifically developed – essentially we have to
consider the full life time of this installation as any failures at
this site could affect our upstream network and associated
customers and risk an un-cleared earth fault condition.
11.1
SCADA requirements
for DNO monitoring of
generation output
Not applicable
The SPEN substation housing policy is scheduled for review
in Quarter 1 2014.
>5MW connected directly to a EHV/HV primary (extended
HV switchboard or HV loop in via sw/stn directly adjacent to
primary) – full SCADA, with ramp down capability (albeit it is
unlikely SPEN will use this function at this time). HH MW &
MVAr
Full SCADA control and associated I/O
taken back to OCC.
>1MW connected directly to a EHV/HV primary (extended
HV switchboard or HV loop in via sw/stn directly adjacent to
primary) – full SCADA, with ramp down capability (albeit it is
unlikely SPEN will use this function at this time). HH MW &
MVAr etc
<1MW no immediate requirement from SPEN at this stage
11.2
12
Power (Battery or
alternative LV supplies)
back-up requirements
Incorporation of the LV
(battery charger etc.)
supply quote into the
overall EHV quote
Facilitation of nonfirm/actively managed
connections - Business
as Usual
It was agreed that the
DNOs would identify
any technical reasons
as to why they cannot
use managed
connections and would
report findings back at
next meeting.
N/A
Existing offers default to 100A supply to align with typical cut- Existing requirement is a supply from the
out ratings. SPEN work with customers where this isn’t
customer’s site with a back-up derived
feasible to identify requirements that may be facilitated.
from the local HV network. Where a local
HV is not feasible, standard back-up
generators are acceptable complete with
an up-rated substation battery
Recognise that were a EHV connection is facilitated
via a tee-off or direct feed to a two panel board may
not
See comments
No technical issues – recognise that the commercial issue is
prevalent with respect generation “zero hour contracts”
Transferred to Commercial Issues Forum;
No technical issues – recognise that the
commercial issue is prevalent with
respect generation “zero hour contracts”
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Technical Issue
LV
HV
EHV
Additional Commentary
DG Technical Issues Forum Meeting #3 – 2 December 2013
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SP Energy Networks – Response to Actions assigned 27 August 2013
DG Technical Issues Forum Meeting #3 – 2 December 2013
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Scottish and Southern Energy (SSE) Response to Actions assigned 27 August 2013
Minute
4
6
Technical Issue
Voltage control /
Voltage rise issues
including the use of
different voltage control
strategies at the
generator level (fixed
power factor, fixed
voltage target, variable,
voltage target etc)
Number of circuit
breakers required for a
generator connection
LV
HV
EHV
Unity power factor
SHEPD require all HV/EHV connecting DG above 200kVA to be able to operate in voltage control mode. We
include this requirement in any offers made. This is to maximise the amount of generation that can be
connected, and minimise the requirement for reinforcement as detailed below.
SEPD require generators to operate at unity power factor.
SSE do not require a separate circuit breaker at the ownership interface. We allow for joint boards i.e. our circuit breakers and customer’s can be in the same room.
Regarding set distance toward customer installation which SSE allow metering circuit breaker to protect: This is a reasonableness test. How much of the
customers network should our breaker protect, how likely is a fault, how inconvenient will it be for a customer to require us to come and switch and
isolate for any work they need to do, how will a customer fault find on their network? We take the pragmatic view that we will protect up to 500 meters.
The requirement to ensure suitable protection and discrimination remains with the customer and so, depending on the characteristics and nature of the
network to be protected, while avoiding the requirement for a breaker, still be obliged to provide the protection and tripping signals to our breaker.
9
Differences in antiislanding requirements
between DNOs
SSE simply require the generator to comply with G59-3; G59-3 Section 10 (10.1.1) states the main reason for the G59 relays (modules) are to provide
for anti-islanding, also see 10.3.5.& 6.
G59 applies for all D-connected schemes, with adjustments for Voltage levels. Additional requirements kick in under Grid code so at 10MW (for
SHEPD), 100MW (for SEPD). See Table 10.5.7.1
10
11.1
11.2
12
Sub-station housing
requirements
SCADA requirements
for DNO monitoring of
generation output
Power (Battery or
alternative LV supplies)
back-up requirements
Incorporation of the LV
(battery chargeretc.)
supply quote into the
overall EHV quote
Facilitation of nonfirm/actively managed
connections - Business
as Usual
It was agreed that the
DNOs would identify
any technical reasons
as to why they
cannotuse managed
connections and would
report findings back at
next meeting.
NA
NA
NA
SSE require SCADA as standard on all ground mounted HV/EHV connected DG sites >200kVA (and everything for Orkney/ any other RPZ or ANM)
and on all sites, whether ground mounted or pole mounted 1MW and above.
General requirements are to cover 72 hours.
Generally, SSE allow actively managed connections. We have tried out in Orkney and are allowing constrained connections in SEPD.
Additional Commentary
DG Technical Issues Forum Meeting #3 – 2 December 2013
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Scottish and Southern Energy (SSE) Response to Actions assigned 27 August 2013
Minute
Technical Issue
LV
HV
EHV
Additional Commentary
DG Technical Issues Forum Meeting #3 – 2 December 2013
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UK Power Networks (DNO) Response to Actions assigned 27 August 2013
Minute
4
Technical Issue
Voltage control /
Voltage rise issues
including the use of
different voltage control
strategies at the
generator level (fixed
power factor, fixed
voltage target, variable,
voltage target etc)
LV
To date we haven’t used any form of
voltage control for generators on the LV
system.
This may be possible in the future.
although we don’t currently have
monitoring of LV voltage to determine if
and by how much this type of control
could give benefit
HV
Same as for EHV
For 11kV - As for the use of voltage regulators we
believe this may be an issue at 11kV on ASC earthed
systems.
EHV
UK Power Networks normally
requires generators to operate at
unity power factor (for import this
would be 0.95 lagging to unity, for
export 0.9 leading to 0.95 lagging)
However, we are currently looking at
operating a PV farm in voltage
control mode rather than fixed
power factor. Our Future Networks
team are looking at this as an IFI
project although we are still waiting
for the customer to build the solar
farm.
Shunt regulators have been used on
offshore wind farms to compensate
for the voltage rise due to cable
charging currents.
Going forward European legislation
will require much more generation
to be capable of operating in this
mode.
6
Number of circuit
breakers required for a
generator connection
Most LV connected generators would be
by a fused cutout. A G59 CB would need
to be provided by customer anyway,
however costs are much less than for HV
CB’s
The requirements at HV are the same as for EHV.
Although the scope for fitting customer CTs within a standard
11 KV metering unit are not really there. If they were required
customer would need to fit these around outgoing cables.
33kV - With regard to the
requirement for the customer to
have his own circuit breaker we have
allowed the customer to make their
own decision. Most customers want
their own breaker to give them
independence to operate their own
networks without relying on us to
have to come to site to isolate and
earth every time they want to work
on their systems.
Where the connection into their
network is short i.e. to a transformer
next to the switch house then we
will allow the customer to fit CT’s
within our breaker for transformer
protection and use our CB to protect
their transformer. However we
won’t allow G59 protection to trip
our metering CB or allow generation
to synchronise through our breaker
so customer needs to provide
something downstream to carry out
these functions.
Additional Commentary
Using reactors to import reactive power as a
means of holding system volts down whilst
drawing large amounts of reactive power
through the system is not ideal and may be
storing up problems for the future. Operating
generators at unity power factor already means
that the network has to make up the reactive
power of the load. Installing reactors as a
means of providing a cheap connection will
make this worse unless it is only for short
periods during minimum load. What we should
be aiming for is a connection that will support
export of reactive power such that the
generators can support the load in terms of
both MW and MVAR.
DG Technical Issues Forum Meeting #3 – 2 December 2013
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Minute
Technical Issue
LV
9
Differences in antiislanding requirements
between DNOs
LOM Protection requirements are in line
with G59
HV
The approach is similar to EHV (33kV) but on Arc
suppression Coil (ASC) networks, NVD is not useable as a
means of protection against islanded conditions where an
earth fault occurs.
EHV
The customer has a duty to protect
their network and where our
metering breaker is used for main
protection there is a potential issue
in that this will often mean that our
source CB acts as backup protection
for faults on the customer LV
network. If this is set too high then
the customer will not have
adequately protected his network.
For 132kV, we are in the process of
developing standards which will
have similar requirements.
Additional Commentary
33kV - Our policy on anti-islanding is
closely aligned with G59 in that we
normally use RoCoF and vector shift
and intertripping for >50MW. We
also use NVD as backup in the event
of islanding due to earth fault.
Where the generator is capable of
producing voltage, current and VArs
required to sustain the power factor
of the site, possible island conditions
could exist and islanding could occur.
This may need to be reviewed in
light of the ENA work on RoCoF
protection.
Reverse VAr protection may be an
option for anti-islanding protection
where synchronous generators are
required to export at or about unity
power factor. However, if generators
are required to operate in voltage
control mode in the future, this form
of protection will not be suitable.
Above 50MW intertripping is the required mechanism
for loss of mains protection rather than ROCoF or
Vector Shift.
For 132kV we are in the process of
developing our standards for
connections.
10
Sub-station housing
requirements
Same as for LV load connections.
As for 33kV.
33kV - Our civil design spec EDS 070020 sets out our requirements for
the establishment of switchrooms.
We will consider most types of
enclosure provided it meets the
general requirements of
environment and clearances.
For 132kV we are in the process of
The use of “turn down” schemes can be a means of
ensuring against islanding. The requirements for
communications paths are not as onerous as
protection requirements.
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Minute
Technical Issue
LV
HV
EHV
developing standards.
11.1
SCADA requirements
for DNO monitoring of
generation output
No SCADA is currently available at
LV.
No SCADA is currently available at 11kV.
11.2
Power (Battery or
alternative LV supplies)
back-up requirements
Incorporation of the LV
(battery charger etc.)
supply quote into the
overall EHV quote
No requirement.
As for EHV
We install SCADA with MW and
MVAr, voltage and current
analogues for all 33kV and above
generation or load connections.
For power supplies we have a
hierarchy of LV supply
arrangements. If we don’t provide
the main LV supply from our existing
11kV network but rely on the
provision of this from the customer
side of the metering we require
customer to provide backup
generator in the event of loss of
main supply.
We used to quote LV supplies in with
the main connection however many
solar farm operators didn’t want this
so we stopped quoting for this
unless customer specifically asks for
it
12
Facilitation of nonfirm/actively managed
connections - Business
as Usual
It was agreed that the
DNOs would identify
any technical reasons
as to why they cannot
use managed
connections and would
report findings back at
next meeting.
Not applicable
As for EHV albeit no such schemes are in place or planned
at the moment.
The increasing number of generator
connections onto the UK Power
Networks system means we are, and
have approached the point where
we are exploring the provision of
non-firm connections.
We are exploring different
mechanisms for the provision of an
operational intertripping path that
meets the requirements of speed
and reliability whilst providing a cost
effective solution for the generator.
This also requires constrainable
connection agreements to be put in
place
Additional Commentary
DG Technical Issues Forum Meeting #3 – 2 December 2013
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UK Power Networks (DNO) Response to Actions assigned 27 August 2013
DG Technical Issues Forum Meeting #3 – 2 December 2013
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Wester Power Distribution (DNO) Response to Actions assigned 27 August 2013
Minute
4
Technical Issue
Voltage control /
Voltage rise issues
including the use of
different voltage control
strategies at the
generator level (fixed
power factor, fixed
voltage target, variable,
voltage target etc)
LV
See additional comments
HV
See additional comments
EHV
See additional comments
Additional Commentary
We normally require generators to operate at a
fixed power factor. A fixed leading power factor
is often specified to alleviate voltage rise issues.
We are in the process of investigating and
trialling the use of generator voltage control
(variable power factor) at a number of locations
with a view to offering this option more widely.
We have some concern that if voltage control
settings are applied at more than one
generating site connected to the same piece of
network, this could conceivably introduce:
1) Hunting / power swings between the
generation sites (i.e. the power factor
at each site could oscillate).
2) Divergence between the power factors
at each site (i.e. one site could operate
at a poor leading power factor and
another site could offset this by
operating at a poor lagging power
factor).
3) An increased risk of islanding as the
generator output is much more likely
to match the load if a section of
network is disconnected from its main
source. This aspect has been
considered by Strathclyde University
and by a joint Grid Code and
Distribution Code sub-group looking at
the impact of frequency disturbances
on generator loss of mains protection.
We would be interested in discussing the above
issues with DNOs and generators who have
experience in using voltage control settings at
multiple generation sites.
We currently have a number of LCNF projects
investigating the use of SVCs and FACTs devices
in to provide a measure of voltage control in
order to facilitate the connection of generation.
Once the results of these projects have been
evaluated we will decide whether such
solutions should be offered more widely.
6
Number of circuit
breakers required for a
generator connection
1, but see also additional comments
1, but see also additional comments
1, but see also additional comments
WPD allow our metering circuit breaker to
protect the generator’s network where their
network is:
1) Not too extensive. For example, we
would not expect to protect long
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Minute
Technical Issue
LV
HV
EHV
Additional Commentary
lengths of customer cable (e.g. in excess
of 100m).
2) Relatively simple. For example, a single
transformer or a single length / section
of cable.
3) At low risk of being damaged or
faulting.
4) Adequately protected.
Our circuit breaker must be adequately rated
for the expected duty and suitable earthing
facilities for both the generator’s network and
our network must be available (either on the
circuit breaker or elsewhere).
For HV and EHV connections we often install
CTs within our circuit breaker, to the
generator’s specification, for the generator’s
protection (e.g. unit protection such as high
impedance, current differential or bias
differential) and monitoring systems. We
generally allow the generator to connect to the
protection winding of our VT, needed and we
also allow the generator’s protection to trip our
circuit breaker where this is appropriate.
We do not allow the generator to control our
circuit breaker, other than for protection
tripping or emergency tripping purposes, or to
use it for synchronising.
We would not expect to have to frequently deenergise or re-energise the generator’s network
via our circuit breaker, either during the
construction phase or subsequently for
maintenance of the generator’s network.
Finally, the generator is responsible for the
protection of their network / equipment (e.g.
under the Electricity at Work Act etc.). The
generator must therefore accept that our circuit
breaker and any associated protection
equipment meets their requirements.
9
Differences in antiislanding requirements
between DNOs
See additional comments
See additional comments
See additional comments
WPD require the anti-islanding protection to
meet the requirements of G59/2-1 or G59/3.
In addition to standard anti-islanding protection
such as RoCoF and / or vector shift, we
sometimes specify intertripping.
Sometimes we also require NVD and / or
DG Technical Issues Forum Meeting #3 – 2 December 2013
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Wester Power Distribution (DNO) Response to Actions assigned 27 August 2013
Minute
Technical Issue
LV
HV
10
Sub-station housing
requirements
Generally HV distribution substations Generally HV distribution substations utilise GRP enclosures WPD allow the use of containerised
utilise GRP enclosures although other although other options are available.
substations where these meet our
options are available.
requirements. Further information
on substation housings is included
within our 33kV, 66kV and 132kV
Connection
Guides
and
the
associated standard drawings. These
guides and drawings are available
from our Technical Information
website,
www.westernpowertechinfo.co.uk.
A copy of our 33kV Connection
Guide and one of the associated
drawings has been submitted with
this response.
11.1
SCADA requirements
for DNO monitoring of
generation output
Generally we do not normally expect
to provide SCADA facilities at these
sites although there may be
exceptions where the generation has
a substantial impact on the network.
Large 11kV connections:
At this time WPD require the following SCADA
facilities:
1) Analogue information (e.g. current, voltage,
watts, vars etc.).
2) Status information (protection, battery and
constraint scheme alarms, switchgear status
etc).
3) Control facilities (control of circuit breakers,
constraint schemes etc.).
The above facilities are generally provided by
conventional substation SCADA system using scanned
UHF telemetry.
Small 11kV Connections with >500kW generation:
We generally require the following SCADA facilities:
1) Limited analogue information that can be
interrogated by our Control Centre (e.g.
current, voltage, watts, vars etc.)
2) Status information (protection, battery and
constraint scheme alarms, switchgear status
etc.)
3) Control facilities (control of switches and
circuit breakers and constraint schemes etc.)
The above facilities are generally provided by
EHV
At this time WPD require the
following SCADA facilities:
1) Analogue information (e.g.
current, voltage, watts, vars
etc.).
2) Status information
(protection, battery and
constraint scheme alarms,
switchgear status etc).
3) Control facilities (control of
circuit breakers, constraint
schemes etc.).
The above facilities are generally
provided by conventional substation
SCADA system using scanned UHF
telemetry.
Additional Commentary
reverse power protection, depending on the
specific circumstances. With regard to NVD
protection, we follow the guidelines (i.e. the
“general rule”) defined in Section 10.4.3 of
G59/2-1 and 10.4.2 of G59/3.
DG Technical Issues Forum Meeting #3 – 2 December 2013
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Minute
Technical Issue
LV
HV
unlicensed radio schemes but licensed radio or other
methods will be used where necessary.
EHV
Additional Commentary
See additional comments
We most cases we require the customer to
provide us with an A.C. LV supply. This LV
supply should ideally be derived from our
network. If the cost of providing a supply from
our network is prohibitive or the associated
earthing issues cannot be resolved, the LV
supply may be derived from the connection to
the generator site. If the supply is derived from
the generator’s network the generator shall:
• Ensure the LV supply to WPD is as
secure as possible. The LV supply must
be maintained if the G59 or generator
protection operates.
• Provide a changeover facility and a plug
/ socket arrangement to allow a
standby generator to be easily and
quickly connected, should this prove
necessary.
• Have processes in place to restore the
LV supply quickly (within a few hours) if
it fails.
Small 11kV Connections with <500kW generation:
Generally we do not normally expect to provide
SCADA facilities at these sites although there may be
exceptions where the generation has a substantial
impact on the network.
11.2
Power (Battery or
alternative LV supplies)
back-up requirements
Incorporation of the LV
(battery charger etc.)
supply quote into the
overall EHV quote
If we need an AC auxiliary supply this will
be derived from our LV equipment.
See additional comments
Note, WPD battery systems are normally rated
for a standby period of 24 hours. If the LV
supply is disconnected for a prolonged period
we will disconnect the site (i.e. open the
metering circuit breaker) on the grounds of
safety.
In the relatively rare cases where WPD have
protection and/or switchgear at the generation
site that is critical for the protection of our
incoming network, we will generally provide our
own LV supply.
12
Facilitation of nonfirm/actively managed
connections - Business
as Usual
It was agreed that the
DNOs would identify
See additional comments
See additional comments
See additional comments
WPD offer actively managed connections. These
range from:
1) Timed Schemes, where different export
capacities are provided during different
periods (e.g. different times of day or
DG Technical Issues Forum Meeting #3 – 2 December 2013
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Wester Power Distribution (DNO) Response to Actions assigned 27 August 2013
Minute
Technical Issue
any technical reasons
as to why they cannot
use managed
connections and would
report findings back at
next meeting.
LV
HV
EHV
Additional Commentary
seasons of the year). This allows
generators to utilise the capacity that is
available during these periods.
2) Conditional Schemes, where generation
is constrained during certain network
configurations (e.g. under back-feed
conditions).
3) Active schemes, where generation is
constrained under certain conditions,
for example where voltage limits or
equipment ratings would otherwise be
exceeded.
DG Technical Issues Forum Meeting #3 – 2 December 2013
th
Wester Power Distribution (DNO) Response to Actions assigned 27 August 2013