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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 1 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 2 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. 3 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 4 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 5 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. 6 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 DG Technical Issues Forum Meeting #3 – 2 December 2013 th SP Energy Networks – Response to Actions assigned 27 August 2013 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 DG Technical Issues Forum Meeting #3 – 2 December 2013 th SP Energy Networks – Response to Actions assigned 27 August 2013 Minute 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” DG Technical Issues Forum Meeting #3 – 2 December 2013 th SP Energy Networks – Response to Actions assigned 27 August 2013 Minute Technical Issue LV HV EHV Additional Commentary DG Technical Issues Forum Meeting #3 – 2 December 2013 th SP Energy Networks – Response to Actions assigned 27 August 2013 DG Technical Issues Forum Meeting #3 – 2 December 2013 th 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 th 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 th 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 th UK Power Networks (DNO) Response to Actions assigned 27 August 2013 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. DG Technical Issues Forum Meeting #3 – 2 December 2013 th UK Power Networks (DNO) Response to Actions assigned 27 August 2013 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 th UK Power Networks (DNO) Response to Actions assigned 27 August 2013 DG Technical Issues Forum Meeting #3 – 2 December 2013 th 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 DG Technical Issues Forum Meeting #3 – 2 December 2013 th Wester Power Distribution (DNO) Response to Actions assigned 27 August 2013 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 th 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 th Wester Power Distribution (DNO) Response to Actions assigned 27 August 2013 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 th 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