Regional Development Plan

Transcription

1 Title: LPN Author: Barry Walker Version: 1.0 Date: June 2013 UK Power Networks (Operations) Limited. Registered in England and Wales.

2 Contents 1. EXECUTIVE UMMARY NETWORK CONFIGURATION EXITING NETWORK EMBEDDED GENERATION PROJECT IN PROGRE Establish New Osborn treet B 132/11kV ubstation Limeburner Lane: Establish New 132/11kV ubstation Plumtree Court Newington House Finsbury Market New Cross Tunnel Calshot treet Cost Phasing for Projects in Progress NETWORK DEVELOPMENT CONIDERATION DEVELOPMENT AREA HI PROFILE WITHOUT INTERVENTION ECURITY OF UPPLY ANALYI OPERATIONAL AND TECHNICAL CONTRAINT NATIONAL GRID PINCH POINT RECOMMENDED TRATEGY PROPOED INTERVENTION Paternoster ubstation ( 947k) horeditch/hearn treet ubstation ( 15,056) Finsbury Market ubstation ( 2,085k) Wellclose quare ( 20,593k incl. 33kV civil works) Devonshire quare/hearn treet/osborn t Permanent 11kV Transfers ( 856k) Glaucus treet and impsons Road 11kV transfers to Wellclose quare ( 856k) Permanent transfers from City Road B and Longford treet to Calshot treet ( 1,407) Finsbury Market: Establish 132kV Interconnection to Osborn treet ( 4,963k) Ludgate Circus ( 2,099k) City Road B & C ( 2,457k) Overstressed witchgear ( 151k) COT AND PHAING HI / LI IMPROVEMENT REJECTED TRATEGIE Template v1.1 Page 2 of 52

3 6. REFERENCE APPENDICE DOCUMENT HITORY DOCUMENT IGN OFF Template v1.1 Page 3 of 52

4 1. Executive ummary The for the Central London network was last captured four years ago. The strategy for the development of the network during DPCR5 has included the introduction of a new 33kV distribution network in the city to facilitate the connection of new large developments with a power demand typically greater than 5MVA. The 33kV network development is now covered by a separate RDP. This document reviews the DPCR5 proposed schemes which impact the HV network and are currently under construction and provides recommendations for future interventions for the ED1 period. The cornerstones of the ED1 strategy involve 11kV capacity injection into the area via new 132/11kV substations at horeditch and Wellclose quare to the north and east of the city respectively. These new substations facilitate 11kV load transfers away from existing substations within the bounds of the LUL Circle Line, which are of a purpose built nature and cannot be reinforced, and provide support to the neighbouring RDP areas of north and east London. The study area covers substations supplied by the City Road GP National Grid exit point. Proposed Interventions The proposed interventions above 1m are as follows: horeditch 132/11kV ubstation Wellclose quare 132/11kV ubstation and associated 11kV load transfers Ludgate Circus atellite 11kV witchboard Asset Replacement / Refurbishment of transformers at Paternoster, City Road B, City Road C, Finsbury Market A and Finsbury Market B Costs profile Table 1: NAMP ummary 14 June 2013 Category Total DPCR4 /2011 /2012 /2013 /2014 /2015 /2016 /2017 /2018 /2019 /2020 /2021 /2022 /2023 /2024 /2025 (Excl. Indirects) Asset Replacement ,266 2,430 1, , ,670 1, ,969 Reinforcement 17,929 4,940 14,180 27,090 29,639 19,099 11,196 3,478 10,124 9,956 11,799 6,721 1,551 3, ,134 Total 17,929 5,183 14,937 29,356 32,070 20,873 11,985 8,207 10,226 13,626 13,634 6,721 1,712 3, ,103 Template v1.1 Page 4 of 52

5 No of substations Output Measures The forecast load indices for 2023, with and without intervention, are detailed below: 12 City Road Load Index Table 2: Load Indices with and without intervention without Intervention 2023 with Intervention LI Value RDP Dependencies and Assumptions This document assumes that all DPCR5 previously approved schemes will progress as currently programmed. The proposal for the redevelopment of horeditch substation is dependent on the completion of the New Cross Finsbury Market tunnel and the installation of the associated 132kV circuits from New Cross. Plumtree Court is dependent on the completion of Limeburner Lane Template v1.1 Page 5 of 52

6 2. Network configuration 2.1. Existing Network The network is fed from City Road 400/132kV National Grid Exit Point, which currently experiences a summer peak of 899MW. Downstream, there is a 132kV cable network feeding predominantly 132/11kV substations and a smaller number of 132/33kV substations. These 132/33kV substations in turn feed a number of 33/11kV primary substations. The number of UK Power Networks owned 33/11kV primary substations is expected to decrease over time as, when dictated by load growth, these are replaced with larger 132/11kV substations housed within the existing buildings (where possible) due to high land values in the area. In turn, the capacity freed up at the existing 132/33kV substations will be used to provide connections to large buildings in the city at 33kV (covered by the 33kV Distribution Network RDP). This strategy will ensure that both 11kV and 33kV load growth is catered for in the most efficient manner by utilising existing assets where possible. The network is predominantly located in the City of London to the north of the River Thames, with the exception of Bankside ubstation, which is located to the south of the Thames in outhwark and shares a building with the Tate Modern. Bankside ubstation is interconnected with the network north of the Thames by an extensive tunnel network. There is also an isolated 20kV network to the south of the Thames fed from Bankside D ubstation. This network is used for new customer connections however also supports a legacy 22kV system in the area which is in the process of being phased out. There is a 22/11kV substation at Newington House (UK Power Networks Head Office) which requires work to enable it to operate with a 20kV source; and a 22/6.6kV substation at Charing Cross Railway tation, which is the only customer on this network that is located north of the Thames. A Geographical Layout of the network can be found in Appendix A; A ingle Line Diagram of the existing network can be found in Appendix B; A chematic Diagram of the tunnel network in the area can be found in Appendix D Embedded Generation Table 3: Output of generating plants used in the analysis Generation Plants Type DNC (MVA) F (%) pf DG Output = F*DNC MVA MW MVAr GUY AND T THOMA' NH FOUNDATION TRUT CHP CITIGEN LONDON LTD CHP OCCUPIER UNKNOWN CHP Note: CITIGEN generators are currently out of service and may be taken offline permanently UK Power Networks (Operations) Limited. Registered in England and Wales.

7 2.3. Projects in Progress Establish New Osborn treet B 132/11kV ubstation Osborn treet substation is located in an ex-power station site in the Whitechapel area of East London. The freehold is owned by EDF Energy and the buildings are within a Conservation Area. There is an existing 33/11kV, 4 x 15MVA substation on site comprising of 4 x 33/11kV, 15MVA transformers supplied via gas filled cables from Finsbury Market B. The 11kV Reyrolle C switchboard has 27 panels with two TFU s (trunk feeder units). The gas cables were installed in July 1956 and are nearing the end of their operational life. Completion of the approved Osborn treet 3 x 66MVA, 132/11/11kV substation is expected in This project has suffered delays as a result of being dependent on the completion of the Finsbury Market New Cross Tunnel (see ection below). The new substation will be supplied by 3 x 132kV circuits via the proposed tunnel. The justification for the project is as follows: Reinforcements will prevent the existing Osborn treet 33/11kV substation and the Finsbury Market B Osborn treet 33kV circuits from going out of firm. Finsbury Market B 33kV will be brought back to within its firm rating The City Road Finsbury Market 132kV circuits will be deloaded to provide 48MW of headroom for the proposed 33kV distribution network. The existing, aged 33kV gas filled cables can be decommissioned Facilitates rationalisation of the surrounding 11kV network. Feeders from Devonshire quare, which run past Osborn treet, will be turned into the new substation to reduce feeder length, improve CIs and CMLs, and deload Devonshire quare by 21MVA to free up capacity for new connections. It should be noted that Devonshire quare is the only substation in this area within the bounds of the Circle line, which is known to be challenging to cross with new circuits. The substation will include a new 13 panel 132kV switchboard to facilitate load transfers between New Cross and City Road GPs as well as providing 132kV points of connection for reinforcement works or customer connections. The 132kV switchboard is shown in Figure 1 below: Figure 1: Osborn treet 132kV ingle Line Diagram Template v1.1 Page 7 of 52

8 Limeburner Lane: Establish New 132/11kV ubstation eacoal Lane ubstation is contained in the basement of eacoal House, located within ¼ mile of Blackfriars and the Old Bailey Law Courts in the City of London. The building was a disused ex-leb, 7 storey office and has recently been demolished to ground floor level and rebuilt to accommodate network reinforcement. Due to a change in the road layout historically surrounding the substation, it is now situated on Limeburner Lane. The substation is therefore being renamed as part of the redevelopment. eacoal Lane ubstation currently consists of a 44 panel, double busbar, 11kV switchboard only. The switchboard consists of three sections: ection 1: Reyrolle C manufactured in x Feeders, 2 x Incomers, 1 x Bus Coupler, 1 x Bus ection ection 2: Alstom WBD manufactured in x Feeders, 4 x Incomers, 4 x Off Load Disconnectors ection 3: Reyrolle C manufactured in x Feeders, 1 x Incomer, 1 x Bus Coupler, 1 x Bus ection It is supplied via 7 x 11kV, 630mm 2, copper, XLPE circuits running through the City Road Farringdon eacoal Lane tunnel (see Appendix D). These circuits have a firm rating of 65.2MVA and due to their length and heavy loading, are the primary heat source and therefore use up the majority of the thermal capacity available within the tunnel. Both City Road C and the circuits feeding eacoal Lane are currently out of firm (LI4), with P2/6 compliance maintained via the post fault transfer of the eacoal Lane W Feeder Group (19MVA) to Paternoster ubstation. Paternoster s switchboard has recently been partially transferred to Bankside C to maintain P2/6 compliance and to free up 33kV capacity at Finsbury Market C for new connections to the City of London 33kV Distribution Network. Limeburner Lane 3 x 66MVA, 132/11/11kV substation is currently under construction, with completion expected in Q The substation is to be supplied via a loop in/out arrangement from existing 132kV cables installed in the City Road to Bankside deep cable tunnel. The new substation will have a summer firm rating of 172MVA due to the transformers being specified as having a 130% cyclic rating for a 12 hour period with an ambient air temperature of 30 0 C. The drivers for the project are as follows: - Maintain P2/6 compliance at City Road C/eacoal Lane - Free up 11kV capacity near to the City Road Basin development and regeneration hub. - Free up space and thermal capacity in the Back Hill Farringdon tunnel for circuits associated with the City of London 33kV Distribution Network (see 33kV Distribution Network RDP). - Provision of 11kV switch positions for surrounding connections activity. The scope of work is as follows: - Cap the existing deep tunnel shaft and remove ventilation (forced exit) - Demolish the existing 7 storey building to ground floor level - Rebuild a fit for purpose structure and substation ventilation scheme - Reinstate the tunnel ventilation scheme - Install 3 x 132kV GI H-points with inline breakers - Install 3 x 132/11kV, 66.6MVA transformers - Install 6 x 132kV circuits from the existing 3 x City Road Bankside 132kV Circuits to loop in/out of the new GI tee points via the Deep Tunnel and Limeburner Lane haft - Install a new 41 panel 11kV switchboard in 2 sections and interconnect to the existing Alstom WBD switchgear, which is to be retained. - Remove the existing 26 panels of Reyrolle C switchgear (HI4) Template v1.1 Page 8 of 52

9 Plumtree Court Goldman achs have requested a 10MVA supply for a site known as Plumtree Court. During the negotiations between UK Power Networks Connections and the customer it was agreed that the customer would provide space for a larger switchboard than they required to be installed. A 31 panel double busbar 11kV, 2500A, switchboard has been proposed (subject to customer acceptance) as per the single line diagram shown in Figure 2 below: PLUMTREE COURT = 10MVA CITY ROAD B N GROUP = 8MVA City Road Incomer 1 NEW T QUARE 4.3MVA City Road Incomer 2 City Road Incomer 3 MB Main RB1 Reserve Limeburner Incomer 1 pare Limeburner Incomer 2 Limeburner Incomer 3 BEECH T B E GROUP = 22MVA FLEET T 120 7MVA (intact) CAXTON HOUE = 8.8MVA Figure 2: Plumtree Court ingle Line Diagram The incoming feeders will be provided by cutting into the existing City Road C eacoal Lane 11kV circuits running through the tunnel system, using two cables per phase in order retain thermal capacity within the tunnel. This project is therefore dependent on the completion of Limeburner Lane. The drivers for the project are as follows: The Beech treet B outh East Feeder Group is overloaded. There are no spare switches and no space for expansion at the substation. In addition, the first legs of this group are approximately 1700m in length. The group is geographically located close to the Plumtree Court site and the project will facilitate reinforcement of this feeder group. City Road B M is approaching firm capacity with a high number of connections referrals allocated. The site is heavily reliant on emergency post fault transfers to maintain compliance. This site is also geographically close to the Plumtree Court site and the project will facilitate reinforcement of this feeder group. New t quare, 1 The customer requires a 4.3MVA olkor connection from the 11kV network. If the customer were connected to Limeburner Lane M, this would utilise two switches and be an inefficient use of the capacity installed at Limeburner Lane. Caxton House Due to the size of the load required (8.8MVA), were it to be connected to Limeburner Lane, it would require the addition of feeders into any existing group or dedicated switches. As the location of Caxton House is better suited to a connection at Plumtree Court, it has been deemed a more appropriate point of connection. Fleet t, 120 This customer is to be supplied from Bankside, but have requested a backup intact only supply from an alternative substation. Again, so as to not under utilise switches at Limeburner Lane, the alternative supply has been assigned to Plumtree Court. Template v1.1 Page 9 of 52

10 Newington House Newington House 22/11kV ubstation is located on the ground floor of Newington House, a seven storey UK Power Networks owned building located at 237 outhwark Bridge Road, London. The other six floors are the UK Power Networks head office. The substation consists of 3 x 15MVA, 22/11kV Transformers fed from Bankside 66/22kV Transformers TE and TF via an isolated section of 20kV switchboard at Bankside D. The current configuration is shown in Figure 3 below: Figure 3: Newington House ingle Line Diagram There is an ongoing rationalisation project at Bankside ubstation driven by asset condition, which involves the installation of a new substation within the east wing of the existing building, releasing the existing west wing to the Tate Gallery who have contributed financially to the project. Newington House Transformers T1, T3 and T4 were manufactured in 1955, 1953 and 1963 and will have health indices of HI3, HI3 and HI4 respectively at the end of the ED1 period. The GEC K5, 27 panel, 11kV switchboard was manufactured in 1954 and 26 of the panels will have a health index of HI5 at the end of the ED1 period. The existing Bankside 66kV Transformers TE and TF will both have a health index of HI5 by the end of the ED1 period and will be removed as part of the Bankside Rationalisation project. upply reinforcement/reconfiguration at Newington House M is necessary because: 1. The substation is currently supplied at 22kV, a voltage level that is being superseded by 20kV. 2. The 20kV system supplied from 132/20kV Yy0 transformers is 30 o out of phase with the existing 22kV system which is supplied from 66/22kV Dy1 transformers. 3. A temporary solution utilising split voltage operation (22kV & 20kV) of the new Bankside D switchboard is in place until Newington House can be re-equipped at 20/11kV. It is necessary to return Bankside D switchboard to 20kV double busbar operation as soon as possible as running the switchboard as single bars puts critical load such as The hard at risk. This arrangement imposes difficulties on required operational flexibility and on extending the Bankside D 20kV switchgear when required to do so. 4. Ambient load growth and a combined 2.4MVA of new connections activity in the Elephant & Castle area will see the load on Newington House substation exceed its installed capacity in summer In addition, outline planning permission has recently been granted for 2500 new homes in the nearby Heygate Estate (circa 7.5MVA of load). Template v1.1 Page 10 of 52

11 The solution being implemented is to replace T1, T3 and T4 with new 3 x 15MVA, 20/11kV Yy0 units and install an additional and equivalent unit T2 in a currently vacant transformer bay. This is recommended because it offers an optimum solution that achieves the correct 11kV phasing, and meets the existing and predicted load at Newington House. Due to the bespoke nature of the transformers required, a fifth unit will be purchased as a strategic spare. The scope of works is as follows: 1. Replace the three existing 15MVA 22/11kV transformers with three new 15MVA 20/kV/11kV transformers, plus the installation of one new additional 15MVA 20/11kV transformer unit. 2. Undertake installation of a new feeder cable from Bankside sub-station to Newington House sub-station 3. Undertake necessary civil works, steelwork, temporary works and fire suppression system works to enable the completion of the works. 4. Carryout the installation of a new UP system in a dedicated room to enable the removal of the existing UP and thus free up the required area for the new switchboard. 5. Construct a new brick-built transformer chamber in the car park to enable the relocation of the existing Ring Main Units. The 11kV switchboard is due for asset replacement (HI5) and as such will be replaced in conjunction with the above substation reinforcement works. Both the reinforcement/reconfiguration and switchboard replacement have been approved at Gate C, with completion expected in Finsbury Market New Cross Tunnel Previously, the recommended strategy was the construction of a fully equipped and ventilated 8.3km deep cable tunnel between Brunswick Wharf and Finsbury Market, and the installation of 3 x 132kV circuits between Brunswick Wharf and Osborn treet ubstations. With City Road 6 x 240MVA GP loaded to near 1GW; and with no space for future reinforcement or expansion of the switchboard, the primary driver was capacity injection into the area from an alternative GP in order to supply the proposed Osborn treet and Wellclose quare ubstations. The establishment of interconnection between GPs provides increased 132kV resilience to City Road, Finsbury Market and Osborn treet, which are the principle substations for supplies to the East End of the City of London. The route planned at that time is shown in Figure 4 below: Template v1.1 Figure 4: Brunswick Wharf Finsbury Market Tunnel Page 11 of 52

12 The justification was as follows: The tunnel, as part of the West Ham GP to City Road GP interconnection delivers key benefits for P2/6 compliance, new customer connections and network resilience while facilitating a coordinated programme of asset replacement and reinforcement (Osborn treet ubstation, Wellclose quare ubstation, Finsbury Market long term rationalisation and P2/6 compliance Detailed route proving including trial openings concluded that traditional open-cut installation between Brunswick Wharf Osborn treet and Osborn treet Finsbury Market was undeliverable due to service congestion, Transport for London (TfL) evacuation routes and 3rd party crossings. Due to the depths to achieve 3rd party crossings directional drilling, micro tunnels and thrust boring (or a combination of each) are technically unsuitable to achieve this connection. The islanded nature of Canary Wharf / Isle of dogs with limited bridge crossings of the docks prevents open-cut installation for the 132kV connections to the new developments at Wood Wharf and Canary Wharf. In addition to general service congestion the main obstacles were 3rd party crossings of the Blackwall and Rotherhithe road tunnels, Docklands Light Railway, Limehouse Link tunnel, Limehouse Basin, Grand Union and River Lee canals and Network Rail Fenchurch treet main Line. National Grid is proposing cross London tunnels between Hackney-t Johns Wood and Wimbledon-t Johns Wood. Completion dates are 2012 and 2016 respectively; however neither route is suitable for diversion to Osborn treet and/or Canary Wharf. Construction of a new tunnel is the only practical solution to delivery the section of the route between Brunswick Wharf and Finsbury Market. The concurrent Canary Wharf reinforcement programme allows for improved utilisation and cost sharing of this asset. Furthermore, Canary Wharf and Wood Wharf are making drive sites available to EDF Energy at nil cost and it is unlikely that suitable drive sites could be identified in a timely manner for tunnel routes to different GP s that do not service the Isle of Dogs. The scheme as planned was dependent upon a ection 16 Connections Agreement with Canary Wharf Contractors Ltd (CWCL) and Wood Wharf Consortium (WWC). This dependency related to both the Customer contribution, and critically the use of key sites at North Quay and Wood Wharf, which would facilitate the connection of the tunnel between Brunswick Wharf and the City section (Wellclose quare/ Osborn t/finsbury Market). As a consequence of this key dependency award of the tunnel contract as planned was not possible and the preferred bidder was stood down. Delivery of the benefits of the scheme were therefore in delay and/or at risk. In parallel with the negotiations with CWCL regarding the Brunswick Wharf to Wellclose route, a study was commissioned to establish the feasibility of an alternative deep cable tunnel route from New Cross ubstation to Wellclose quare to eliminate the requirement for the Connection Agreement. Due to time constraints related to the need for reinforcement at Osborn treet and the associated capacity release for the City of London 33kV Distribution Network, the tunnel project was split into three phases to allow for the project to progress in parallel with the above negotiations and feasibility study. The study has since confirmed that a tunnel from New Cross GP is feasible and this was selected on the basis of both financial (no customer contribution) and feasibility considerations. tage Tunnel ection tatus 1 Osborn treet haft & connecting tunnel Completed October Wellclose quare to Finsbury Market tunnel 3 New Cross to Wellclose quare tunnel and 3 x 132kV circuits to Osborn treet Contract awarded, under construction, planned completion eptember 2013 Approved eptember 2012, expected completion in Q Template v1.1 Page 12 of 52

13 The revised route for tage 3 is shown in Figure 5 below: Figure 5: New Cross to Wellclose quare Tunnel The revised route also provides the opportunity to develop a future tunnel connection at the Drummond Road shaft via an east facing chamber. This could facilitate the proposed 223 Westferry Road 132kV substation, which is subject to formal customer agreement, but could be required for commissioning in 2015/6. This is covered in more detail in the New Cross RDP Calshot treet Calshot treet is a UK Power Networks leasehold site strategically located 500m east of London Kings Cross railway station. In 1978, London Borough of Islington granted London Electricity Board an 80 year lease of the site. In 1999, Peabody Trust took over ownership of the site. As the site has not been in continuous use for operational purposes, it is not possible to make use of permitted development rights and a full planning application is required. Two existing 132kV, 630mm 2 Aluminium Conductored, XLPE insulated circuits, which feed Canal treet M, pass within 100m of the Calshot treet site. ince Canal treet is contracted for a maximum demand of 45MVA, there is capacity in the circuits to connect a 2 x 66MVA 132/11kV primary substation. The N-1 summer cyclic rating of the circuits is 152MVA. The establishment of Calshot treet Main ubstation allows load to be transferred from Back Hill A 11kV and City Road B 11kV (both LI4). The load on Back Hill A 11kV exceeds the firm capacity of the substation, with Engineering Recommendation P2/6 compliance maintained via 11kV post fault transfers. City Road B 11kV currently has 15MVA of spare capacity available but has 27.5MVA (diversified at 0.8) of connections applications allocated to it. As well as relieving loading issues in the surrounding network, this new Main ubstation will provide spare 11kV circuit breakers. These spare breakers give flexibility to the surrounding network and also allow timely connection of new HV customers. There has been an informal expression of interest for an 8MVA supply to Euston tation with N-3 security for the High peed 2 rail project as well as an additional 7.5MVA traction supply. Template v1.1 Page 13 of 52

14 Calshot treet 11kV City Road B 11kV Back Hill 11kV Figure 6: Calshot treet Map of Associate ubstations Cost Phasing for Projects in Progress NAMP Ref Description DPCR Osborn t: Establish new Osborn treet B 132/11kV ubstation 2010 / / / / / / /2017 Total (Excl. Indirects) 8,781 3,012 3,168 8,444 7,331 1, , Limeburner Lane: Establish new 132/11kV ubstation 5,301 1,089 3,620 9,111 8, , Calshot treet: Establish 2x66MVA 132/11kVsubstation ,081 1,516 8, New Cross - Wellclose quare Cable Tunnel Construction_JN Feb 2013 (ED1 Costs Only) , , Finsbury Mkt-New Cross Tunnel: Install 3x132kV ccts , , Construct Wellclose quare to Finsbury Market Cable Tunnel 3,846 1,064 6,885 7,698 1, , Finsbury Market: Deep cable tunnel extension , , New Cross - Wellclose quare Cable Tunnel Construction_JN Feb ,280 10, , Finsbury Mkt-New Cross Tunnel: Install 3x132kV ccts , , Newington House: 11kV witchboard Replacement , , Newington House: Reconfiguration to new Bankside ubstation ,557 1, ,340 Total (Excluding Indirect Costs) 17,929 5,694 14,752 28,356 31,976 20,428 10,102 1,516 Total by Regulatory Review Period 17, ,206 11, ,752 Template v1.1 Page 14 of 52

15 3. Network Development Considerations 3.1. Development areas Heygate Estate Elephant & Castle: Outline Planning Permission granted for 2500 new homes (circa 7.5MVA of load) City Road Basin Islington: 259 City Road (P092620). An application was approved in April 2010 for the erection of a building of part 14, part 17 and a 31 storey tower comprising 304 residential units and ground floor commercial floor space. Work has now started on site. 261 City Road (P041872). An application was approved in December 2006 for the erection of 36 storey building and two 8 storey buildings to provide 308 residential units and ground floor commercial uses. City of London - The development pipeline can be found in Appendix E. Tower Hamlets The Proposals Map can be found in Appendix F HI Profile Without Intervention Table 4: HV Circuit breakers ubstation No. HI1 No. HI2 No. HI3 No. HI4 No. HI5 No. HI1 No. HI2 No. HI3 No. HI4 No. HI5 BEECH T A BEECH T B CITY RD B 11KV CITY RD C 11KV DEVONHIRE Q FINBURY MKT A 11KV FINBURY MKT D 11KV FINBURY MKT E 11KV HEARN TREET OBORN T 27 PATERNOTER EACOAL LANE 11KV Table 5: EHV Circuit breakers ubstation No. HI1 No. HI2 No. HI3 No. HI4 No. HI5 No. HI1 No. HI2 No. HI3 No. HI4 No. HI5 FINBURY MARKET B 33KV FINBURY MARKET C 33KV HOXTON 33KV 2 2 MANELL T (LUL) 22KV 4 4 Template v1.1 Page 15 of 52

16 Table 6: 66 and 132kV Circuit Breakers ubstation No. HI1 No. HI2 No. HI3 No. HI4 No. HI5 No. HI1 No. HI2 No. HI3 No. HI4 No. HI5 CITY ROAD 132KV HOREDITCH 66KV Table 7: Grid Transformers ubstation No. HI1 No. HI2 No. HI3 No. HI4 No. HI5 No. HI1 No. HI2 No. HI3 No. HI4 No. HI5 BEECH TREET B 3 3 CANAL TREET 2 2 CITY ROAD B 11KV CITY ROAD C 11KV DEVONHIRE Q FINBURY MARKET B 33KV FINBURY MARKET C 33KV FINBURY MKT A 11KV FINBURY MKT E 11KV HEARN TREET HOXTON 33KV 1 1 MANELL T (LUL) 22KV 2 2 Table 8: Primary Transformers ubstation No. HI1 No. HI2 No. HI3 No. HI4 No. HI5 No. HI1 No. HI2 No. HI3 No. HI4 No. HI5 BEECH T A 2 2 FINBURY MKT A 11KV 1 1 FINBURY MKT D 11KV OBORN T 4 PATERNOTER Template v1.1 Page 16 of 52

17 3.3. ecurity of supply analysis Table 9 below is the P2/6 assessment table for City Road, which takes into account interventions proposed in this RDP Table 9: P2/6 Assessment Table (Continued overleaf ) Winter 22/ 23 ummer 2022 (M W) Winter 21/ 22 ummer 2021 (M W) Winter 20/ 21 ummer 2020 (M W) Winter 19/ 20 ummer 2019 (M W) Winter 18/ 19 ummer 2018 (M W) Winter 17/ 18 ummer 2017 (M W) Winter 16/ 17 ummer 2016 (M W) Winter 15/ 16 ummer 2015 (M W) Winter 14/ 15 ummer 2014 (M W) Winter 13/ 14 ummer 2013 (M W) Winter 12/ 13 ummer 2012 (M W) P. F. Generation (MW w ith F% Applied) Transfer (MW) Firm Capacity (MW) econdary Voltage Type of substation Grid upply Point ub-station P2/6 City Road 132kV City Road 132kV YE GP 132kV City Road 132kV City Road 132kV YE GP 132kV City Road 132kV City Road B YE Grid 11kV City Road 132kV City Road B YE Grid 11kV City Road 132kV Calshot treet YE Grid 11kV City Road 132kV Calshot treet YE Grid 11kV UK Power Networks (Operations) Limited. Registered in England and Wales. City Road 132kV City Road C YE Grid 11kV City Road 132kV City Road C YE Grid 11kV City Road 132kV Canal treet YE Grid 11kV City Road 132kV Canal treet YE Grid 11kV City Road 132kV Beech treet B YE Grid 11kV City Road 132kV Beech treet B YE Grid 11kV t Johns Wood 132kV Back Hill 33kV YE Grid 33kV t Johns Wood 132kV Back Hill 33kV YE Grid 33kV t Johns Wood 132kV Back Hill 33kV T1,2,3 YE Grid 33kV t Johns Wood 132kV Back Hill 33kV T1,2,3 YE Grid 33kV City Road 132kV Back Hill 33kV T4 YE Grid 33kV City Road 132kV Back Hill 33kV T4 YE Grid 33kV t Johns Wood 132kV Back Hill YE Grid 11kV t Johns Wood 132kV Back Hill NO Grid 11kV t Johns Wood 132kV Back Hill T1,2,3 YE Grid 11kV t Johns Wood 132kV Back Hill T1,2,3 YE Grid 11kV City Road 132kV Back Hill T4 NO Grid 11kV City Road 132kV Back Hill T4 NO Grid 11kV City Road 132kV Hoxton N/A Customer 33kV City Road 132kV Hoxton N/A Customer 33kV City Road 132kV Mansell treet 22kV LUL N/A Customer 22kV City Road 132kV Mansell treet 22kV LUL N/A Customer 22kV City Road 132kV City Rd eacoal Bankside F Group YE Group Load 132kV City Road 132kV City Rd eacoal Bankside F Group YE Group Load 132kV City Road 132kV Limeburner Lane YE Grid 11kV City Road 132kV Limeburner Lane YE Grid 11kV City Road 132kV Bankside F YE Grid 132kV City Road 132kV Bankside F YE Grid 132kV City Road 132kV Bankside C YE Grid 11kV City Road 132kV Bankside C YE Grid 11kV City Road 132kV Bankside C Total YE Grid 11kV City Road 132kV Bankside C Total YE Grid 11kV City Road 132kV Paternoster YE Primary 11kV City Road 132kV Paternoster YE Primary 11kV City Road 132kV Bankside D YE Grid 20kV City Road 132kV Bankside D YE Grid 20kV City Road 132kV Bankside D 20kV Group YE Group Load 20kV City Road 132kV Bankside D 20kV Group YE Group Load 20kV City Road 132kV Charing Cross 6.6kV. YE Primary 6.6kV City Road 132kV Charing Cross 6.6kV. YE Primary 6.6kV New Cross 66kV New ington House YE Primary 11kV New Cross 66kV New ington House YE Primary 11kV City Road 132kV New ington House. YE Primary 11kV City Road 132kV New ington House. YE Primary 11kV City Road 132kV Devonshire quare YE Grid 11kV City Road 132kV Devonshire quare YE Grid 11kV

18 ub-station P2/6 Type of substation econdary Voltage Firm Capacity (MW) Transfer (MW) Generation (MW w ith F% Applied) P. F. City Road to Finsbury Circuits YE Circuits 132kV City Road to Finsbury Circuits YE Circuits 132kV Finsbury Market A YE Grid 11kV Finsbury Market A YE Grid 11kV Finsbury Market A T1 T2 T3 YE Grid 11kV Finsbury Market A T1 T2 T3 YE Grid 11kV Finsbury Market A T4 YE Grid 11kV Finsbury Market A T4 YE Grid 11kV Finsbury Market B 33kV YE Grid 33kV Finsbury Market B 33kV YE Grid 33kV Whiston Road T1 YE Primary 11kV Whiston Road T1 YE Primary 11kV Finsbury Market C 33kV YE Grid 33kV Finsbury Market C 33kV YE Grid 33kV Beech treet A YE Primary 11kV Beech treet A YE Primary 11kV Brick Lane N/A Customer 33kV Brick Lane N/A Customer 33kV Finsbury Market D YE Primary 11kV Finsbury Market D YE Primary 11kV Finsbury Market E YE Grid 11kV Finsbury Market E YE Grid 11kV Osborn treet YE Primary 11kV Osborn treet YE Primary 11kV Winter 12/ 13 ummer 2012 (M W) Winter 13/ 14 ummer 2013 (M W) Winter 14/ 15 ummer 2014 (M W) Winter 15/ 16 ummer 2015 (M W) Winter 16/ 17 ummer 2016 (M W) Winter 17/ 18 ummer 2017 (M W) Winter 18/ 19 ummer 2018 (M W) Winter 19/ 20 ummer 2019 (M W) Winter 20/ 21 ummer 2020 (M W) Winter 21/ 22 ummer 2021 (M W) Winter 22/ 23 ummer 2022 (M W) Osborn treet (132/11) YE Grid 11kV Osborn treet (132/11) YE Grid 11kV Hearn treet. YE Grid 11kV Hearn treet. YE Grid 11kV Template v1.1 Page 18 of 52

19 The summer peak load currently exceeds the N-1 nameplate rating at Back Hill A 11kV, Finsbury Market A T1, T2 & T3, Finsbury Market B 33kV and Osborn treet 11kV substations. P2/6 compliance is maintained via post fault load transfers to adjacent sites for all of the above with the exception of Back Hill A 11kV, where there is insufficient transfer capacity available. This issue will persist until 2015, when Calshot treet substation will be completed to enable Back Hill A 11kV to be deloaded. It is recommended that an At Risk study is carried out to determine the summer cyclic capability of the Back Hill A transformers and if necessary a derogation application submitted to Ofgem on the grounds that any interim investment to deal with this issue would be an inefficient use of capital. The 2015 and 2023 Load Index per substation, should no interventions be made, is shown below: City Road ubstation Voltage Load Index kv City Road 132kV Beech treet A 33/ Beech treet B 132/ City Road B 132/ City Road C 132/ Devonshire quare 132/ Finsbury Market A 132/ Finsbury Market B 33kV 132/ Finsbury Market D 33/ Finsbury Market E 132/ Hearn treet 66/ Osborn treet 33/ Paternoster 33/ Tooley t via Bankside 132/ Bankside C Total 132/ Bankside D 132/ Operational and technical constraints 1) There will be 62MVA of spare capacity available at Limeburner Lane ubstation on completion; however open cut cable routes to the west of the substation are not feasible due to the barrier created by the Thameslink Railway Line. The City Road Bankside tunnel system is the only route out in this direction via an intermediate shaft in Farringdon Road. pace and thermal constraints in the City Road Limeburner Lane tunnel need to be carefully managed at this network critical pinch point. 2) The Finsbury Market C Beech treet A Paternoster 33kV fluid filled cables have a historically high leak rate, with the Beech treet A Paternoster section being in the worst 8% in the LPN area, averaging 4945 litres leaked per annum over the last decade. Recent repair work and deloading due to a temporary load transfer from Paternoster to Bankside has seen this figure drop to 425 litres in The Finsbury Market C Beech treet A section is less urgent, with an average leak rate of 421 litres per annum over the past decade. 3) The following 11kV feeder groups are on the Distribution Planning Hotspots List and are considered in this document to identify synergies with the substation reinforcement needs of the area: eacoal Lane N Group Load will exceed N-1 firm capacity once already connected load ramps up to its notified maximum demand Template v1.1 Page 19 of 52

20 Paternoster NE Group Feeder NE1 overloaded during a recent hot spell. This olkor group shares load unequally and needs to be reinforced Hearn treet NE Group Feeder NE3 overloaded. This will be reinforced to a five feeder group but is dependent on the completion of the new Osborn treet substation Glaucus treet NW Group Overloaded under N-1 conditions. City Road B NE Group There are a large amount of connections referrals allocated to this feeder group. This will see the group fully loaded if these proceed. Reinforcement options are to be investigated. City Road B N Group Cable sections overloaded for an outage on feeder N4 Beech treet B E Group mall section conductor sections on feeders E1 and E5 overloaded 4) The following transformer replacement works need to be considered in conjunction with the reinforcement needs for the area: One of the four Paternoster 33/11kV transformers will require replacement due to condition in ED1 Two of the City Road B 132/11kV transformers will require replacement due to condition in ED1 One of the City Road C 132/11kV transformers will require replacement due to condition in ED1 One of the Hearn treet 66/11kV transformers require replacement due to condition in ED1 5) The following switchgear is overstressed: Table 10: Overstressed witchgear Voltage ystem Existing Fault Rating ubstation Node Name Level Impedance R X ystem Peak RM Fault Peak Break Make Break Make kv % on 100 MVA ka ka ka ka Finsbury Market B 33kV FINB base Finsbury Market C 33kV FINC ) The City Road Finsbury Market 132kV circuits are in violation of Engineering Recommendation P18 Complexity of 132kV Circuits. Restriction B states that Not more than three transformers shall be banked together on any one circuit at any one site. However, Finsbury Market four banked transformers on site (ubstations A, B, C & E). Furthermore, these circuits are then double banked with Devonshire quare and Hoxton transformers back at City Road GP National Grid An application is to be made for a 4th GT at New Cross 132kV GP to maintain (N-2) P2/6 compliance. A UK Power Networks funded extension to the switchhouse will be required to accommodate National Grid's 132kV circuit breaker. This project is covered in detail in the New Cross RDP. Template v1.1 Page 20 of 52

21 3.6. Pinch Points A schematic diagram of the existing City Road Bankside tunnel can be found in Appendix D. While the construction of this tunnel has been necessary to provide a means of capacity injection into the City of London, it has also created a network critical pinch point. The worst conceivable event would be a fire near the Farringdon Limeburner Lane spur tunnel section. This would result in the loss of 251MW of load, of which only 52MW can be restored from alternative sources: Table 11: Load at Risk for Tunnel HILP Event ubstation Loading (MW) Transferable (MW) Load Lost (MW) Limeburner Lane Paternoster Bankside C CoL 33kV Network Plumtree Court Total Template v1.1 Page 21 of 52

22 4. Recommended trategy 4.1. Proposed Interventions Paternoster ubstation ( 947k) There is a need to replace/decommission one of the four 33/11kV transformers at Paternoster substation. The 33kV Fluid Filled cables feeding the site have historically had a high leak rate, however as a result of recent repair work and/or deloading due to the majority of the load being temporarily supplied from Bankside C, the leak rate had dropped significantly. In addition, there is the need to reserve capacity at Finsbury Market C for 33kV connections commitments (see 33kV Network RDP), which is the source for the above fluid filled cables. The following options have been considered for the site: 1) Do Nothing - 0k 2) Asset Replace Transformer T4 and transfer Paternoster to Finsbury Market B 33kV ubstation - 947k (Recommended) 3) Asset replace Transformer T4, overlay the 33kV fluid filled circuits and transfer Paternoster to Finsbury Market B 33kV ubstation - 3,073k 4) Upgrade Paternoster to a 132/11kV, 3 x 33.3MVA substation fed from Limeburner Lane - 5,183k 5) Upgrade Paternoster to a 132/11/11kV, 2 x 66.6MVA substation fed from Osborn treet - 12,554k Options 2, 3 & 5 are dependent on the completion of the new Osborn treet 132/11kV substation and the New Cross Osborn treet new section of tunnel. Option 2 & 3 because of capacity constraints on Finsbury Market B and the City Road Finsbury Market 132kV circuits, which will be deloaded by 48MW once Osborn treet is completed; and Option 5 because the new Osborn treet 132kV switchboard will be used to supply the substation. This is also a requirement in order to prevent there being a constraint on the capacity available for 33kV connections from Finsbury Market C due to the heavily loaded upstream City Road Finsbury Market 132kV circuits. This is a prudent dependency as there has been a rapid take-up of 33kV new connections in the city. Both Option 4 & 5 above are dependent on the asset replacement of the Paternoster 11kV switchboard, due to the rating of the 11kV incoming circuit breakers, and as such will need to be programmed to be delivered concurrently, meaning that the 11kV switchboard replacement will need to be brought forward to ED1. All the above except for Do Nothing will allow the 11kV circuits temporarily feeding Paternoster from Bankside C via the tunnel system to be partially reused to facilitate the replanting of horts Gardens ubstation (see t Johns Wood RDP). Template v1.1 Page 22 of 52

23 A schematic diagram of the existing tunnel system and the feeding arrangement for Paternoster substation is shown in Figure 7 below. Limeburner Lane, which will be completed in 2015, is shown as such: To City Road & Back Hill Limeburner Lane Paternoster Plumtree Court To Finsbury Market C via Beech t A To Fisher treet via Kingsway and horts Gardens 33kV Network Thameslink Box Bankside Figure 7: Existing Tunnel ingle Line Diagram Option 1: Do Nothing ( 0k) If the system was left running in the temporary arrangement currently in place, then there would be the following disadvantages: It would not be possible to provide the temporary 11kV supply to horts Gardens from Bankside C in order to facilitate the redevelopment of the substation (ee t Johns Wood RDP). Capacity and switch positions for 33kV distribution connections would not be created at Finsbury Market C. The HILP pinch point issue described in ection 3.7 would remain. Transformer capacity at Paternoster would be lost as three of the transformers would remain out of service. Due to the strategic position of this substation, within the bounds of the Circle line, this would be counterintuitive. The temporary arrangement uses 60MVA of the 11kV capacity available at Bankside C, which would not be recovered if the network was left as is. Based on the above, the option of doing nothing is rejected. Template v1.1 Page 23 of 52

24 Option 2: Asset Replace Transformer T4 and transfer Paternoster to Finsbury Market B 33kV ubstation (Recommended) - 947k This option is for the like for like replacement of Paternoster 33/11kV Transformer T4. hould this option go ahead it is recommended that the exisitng 33kV cables are terminated to the adjacent Finsbury Market B 33kV so that Finsbury Market C 33kV can be dedicated to making new 33kV distribution connections. This option is shown in Figure 8 below: To City Road & Back Hill Limeburner Lane Plumtree Court Paternoster T1 T2 T3 T4 Existing FFCs terminated at Finsbury Market B To Fisher treet via Kingsway and horts Gardens 33kV Network Circuits freed up to facilitate the replant of horts Gardens Thameslink Box Bankside Figure 8: LD with Paternoster Transferred to Finsbury Market B & T4 Replaced Due to capacity constraints on the City Road Finsbury Market 132kV circuits, this option is dependent on the completion of the new Osborn treet 132/11kV substation, which deloads these circuits by 48MW. A major drawback of this option is that, if implemented before the completion of the Osborn treet Finsbury Market 132kV interconnection, then it reduces the capacity available for making new 33kV connections in the city by 36MVA from the current arrangement and by a total of 47MVA should Options 3 or 4 be implemented. Also, it does not increase the 11kV capacity availability in the area. As there has been a rapid take-up of this 33kV capacity for new connections, it is recommended that Finsbury Market 132kV is first partially transferred to New Cross GP via the new Osborn treet 132kV switchboard and new tunnel system to Finsbury Market. This option is recommended on the basis that it is the least costly and least complex when compared to options 3, 4 & 5. In addition, there is no need to advance the Paternoster 11kV switchboard replacement into ED1 as the incomers are sufficiently rated. Template v1.1 Page 24 of 52

25 Option 3: Asset Replace Transformer T4, overlay the 33kV fluid filled circuits and transfer Paternoster to Finsbury Market B 33kV ubstation ( 3,073k) This option is for the like for like replacement of Paternoster 33/11kV Transformer T4 and the 33kV Fluid Filled Cables feeding the site from Finsbury Market C 33kV. hould this option go ahead it is recommended that the new 33kV cables are terminated to the adjacent Finsbury Market B 33kV so that Finsbury Market C 33kV can be dedicated to making new 33kV distribution connections. This option is shown in Figure 9 below: To City Road & Back Hill Limeburner Lane Plumtree Court Paternoster T1 T2 T3 T4 4 x 1.35km Cable Route (plus 2 x 900m tee to Beech t A) through the City Centre Overlaid circuits terminated at Finsbury Market B To Fisher treet via Kingsway and horts Gardens 33kV Network Circuits freed up to facilitate the replant of horts Gardens Thameslink Box Bankside Figure 9: LD with Paternoster Transferred to Finsbury Market B, 33kV Circuits Overlaid & T4 Replaced Due to capacity constraints on the City Road Finsbury Market 132kV circuits, this option is dependent on the completion of the new Osborn treet 132/11kV substation, which deloads these circuits by 48MW. A major drawback of this option is that, if implemented before the completion of the Osborn treet Finsbury Market 132kV interconnection, then it reduces the capacity available for making new 33kV connections in the city by 36MVA from the current arrangement and by a total of 47MVA should Options 3 or 4 be implemented. Also, it does not increase the 11kV capacity availability in the area. As there has been a rapid take-up of this 33kV capacity for new connections, it is recommended that Finsbury Market 132kV is first partially transferred to New Cross GP via the new Osborn treet 132kV switchboard and new tunnel system to Finsbury Market. This option is rejected however, on the basis that the leak rate of the Finsbury Market Paternoster 33kV circuits has reduced significantly due to repair work and/or temporary deloading. Before these circuits are loaded up again and the leak rate monitored (subject to the City Road Finsbury Market 132kV circuit deloading provided by the Osborn treet transfer to New Cross GP) the performance of these cables will not be fully understood. Therefore, no provision has been made for their condition based replacement in ED1; however should they begin to leak severely again then the replacement work will be brought forward. Template v1.1 Page 25 of 52

26 Option 4: Upgrade Paternoster to a 132/11kV, 3 x 33.3MVA substation ( 5,183k) This option is for the removal of the existing four 33/11kV transformers and the installation of 3 x 132/11kV, 33.3MVA transformers. The transformers will be fed from Limeburner Lane by three new 132kV circuits run through the tunnel connecting these sites. The length of the new circuits will be approximately 300m each. This option is shown in Figure 10 below: To City Road & Back Hill Limeburner Lane Paternoster Plumtree Court To Fisher treet via Kingsway and horts Gardens 33kV Network Circuits freed up to facilitate the replant of horts Gardens Thameslink Box Bankside Figure 10: LD with Paternoster Upgraded to a 3 x 33.3MVA, 132/11kV ubstation The preference would be for open 132kV bushing type transformers due to testing and maintenance requirements, however there are height restrictions within the transformer chambers of this underground site which will need to be taken into account during the design stage. A minimum 132kV electrical clearance of 1.1m is required. Figure 11 shows the 33.3MVA transformer which will be used at Fisher treet (see New Cross RDP) within a Paternoster transformer chamber. It appears that the necessary clearances will be achievable, albeit by a small margin; however 3D modelling will be required to confirm this due to the presence of a ceiling support beam. Template v1.1 Page 26 of 52

27 Figure 11: Paternoster Transformer Chamber with a 33.3MVA, 132/11kV Transformer Installed A major disadvantage of this option is that it utilises all of the remaining 132kV points of connection at Limeburner Lane, which could otherwise be used for future mitigation against the HILP event described in ection 3.7. As there are only four bays available at Paternoster, with three being used for the proposed transformers, it is unlikely that suitable 132kV tee points could be accommodated to solve this problem in the future. This option is rejected on the basis of cost, complexity and the above potential future HILP mitigation consideration. Template v1.1 Page 27 of 52

28 Option 5: Upgrade Paternoster to a 132/11/11kV, 2 x 66.6MVA substation ( 12,554k) This option is for the removal of the existing four 33/11kV transformers and the installation of 2 x 132/11kV, 66.6MVA transformers and 2 x 132kV GI Tee Points. The transformers will be fed from Osborn treet by two new circuits to Limeburner Lane, teed to the new transformers. As this will only be a two transformer site, with a transformer out for maintenance the total substation load would be at risk for a second circuit outage. In order to provide N-2 support to Paternoster and improve Quality of upply, it is proposed that an 86MVA, 11kV interconnector is installed between Limeburner Lane and Paternoster. The existing three 800mm 2 copper circuits currently feeding Paternoster from Bankside can be partially reused, with a fourth circuit being installed in order to create two double banked interconnectors. Two new three panel 11kV switchboards will be required at Limeburner Lane to facilitate the 11kV interconnection to Paternoster. The proposal is shown in Figure 12 below: To City Road & Back Hill Limeburner Lane Paternoster T3 T2 T1 Plumtree Court 432m Cable Route N/O N/O 2.75km Cable Route through the City Centre To Osborn treet 132kV witchboard, Teed with GT1, 2 & 3 These circuits should be open cut if possible to mitigate against a fire in the Limeburner Lane haft To Fisher treet via Kingsway and horts Gardens 33kV Network Turn existing 11kV feeders from Bankside C into Limeburner Lane to provide a 86MVA load transfer under N-2 conditions Circuits freed up to facilitate the replant of horts Gardens Thameslink Box Bankside Figure 12: LD with Paternoster Upgraded to a 2 x 66.6MVA, 132/11/11kV ubstation In order to provide the most effective HILP mitigation against a tunnel fire, the Paternoster - Limeburner Lane section of the new circuits will be open cut. The route length of the new circuits will be approximately 2.75km for the Osborn - Paternoster section and 432m for the Paternoster - Limeburner Lane section. Open 132kV bushing type transformers will not be feasible for this option due to height restrictions in this underground site. As such, 132kV cable box terminations will be utilised. It will therefore be necessary to incorporate a 132kV test point in the GI tee points. Template v1.1 Page 28 of 52

29 The 132kV feeding position on the Osborn treet switchboard is shown in Figure 13 below: Paternoster 132kV Paternoster 132kV Figure 13: Osborn treet F 132kV Connection Points for Paternoster Upgrade The proposed running arrangement at Limeburner Lane is shown in Figure 14 below: T1 T2 All witchgear Rated 2500A Cable Interconnection to Paternoster via tunnel 2 x 800sqmm Cu per phase (Used for N-2 upport Only) N GROUP To be split up 26.7 MVA PATERNOTER 0476 LIMA ection-1 (Ex EAL ection- 2) Refurbished AREVA WBD 2500A NN GROUP 7.4 MVA Ref , Old Bailey & 60, Ludgate Hill 7.5 MVA M 43 R P A R E P A R E P A R E 1250A 1250A GROUP 15.6 MVA P A R E P A R E KE GROUP 2.5 MVA P A R E Cable Interconnections 2x 800mm2Cu per phase P A R E P A R E P A R E A 1250A ECTION-2 iemens NX+ 2500A P A R E 3x double banked circuits to Plumtree Ct. atelite Board P A R E ECTION-3 iemens NX+ 2500A Must be rated 1250A KH GROUP 6 MVA A 1250A P A R E P A R E Ref HOLBORN VIADUCT, MVA NEW FETTER LANE 2.3 MVA W GROUP 19.1 MVA NC Group ONE NEW CHANGE 12.6 MVA I M R CITB N1 I Normal 30.8MVA Max 40.8MVA Only acceptable after 3 rd transformer is online 2.3 MVA BACK UP KINGWAY E3 (P-26) Figure 14: Limeburner Lane 11kV Interconnection to Paternoster T3 This option offers the highest level of system resilience, however is the most costly and need only be pursued if it is establish that there is a business / regulatory need to secure the City of London network against the HILP event(s) described ection 3.7. Template v1.1 Page 29 of 52

30 horeditch/hearn treet ubstation ( 15,056) horeditch 66kV witching tation and Hearn treet 66/11kV ubstation are situated on the same site in Hearn treet. The existing single line diagram and summer peak load flow is shown in Figure 15 below: Figure 15: Load Flow for Existing Hackney Holloway 66kV ystem Five of the six 66kV breakers at horeditch are in poor condition and in need of asset replacement. In addition one of the three transformers and eighteen of the of the thirty-one 11kV circuit breakers at Hearn treet required replacement. The five BTH OW409 66kV oil circuit breakers date from 1931 and are all HI5. The OCB mechanisms, OCB bushings and through-roof oil filled bushings are all in very poor condition. Many of bushings are suffering from oil leaks of varying severity. Due to the nature of the site and bus bar configuration, it is not possible to economically repair or replace the bushings. It is not possible to repair or refurbish the circuit breakers and they need to be replaced or otherwise removed from service. Operation of the 66kV circuit breakers results in a significant hazard to personnel. During closing, the trip linkage bar needs to be supported manually so that the breaker does not trip free again (from the vibration associated with closing). This has to be done locally, with the operator adjacent to the circuit breaker during closing. If the circuit breaker was faulty, or closed onto a circuit fault, the manual support of the trip bar would potentially prevent tripping, possibly leading to catastrophic failure of the circuit breaker while the operator was adjacent to it. Replacement/decommissioning of these breakers within DPCR5 would contribute toward meeting our EHV Breaker HI Improvement targets for the period. The current position is shown in Figure 16 below: Figure 16: DPCR5 HI Target vs Actual & Forecast Template v1.1 Page 30 of 52

31 The building itself is in need of repair, with the roof in particularly poor condition. ome concrete has already fallen and been secured with steel mesh and in the vicinity of the OCB bays there is evidence of spalling and deterioration of the civil structure. The 66kV circuits feeding horeditch were installed in 1932, with the 6.7km cables from Hackney Grid being Fluid Filled. The New Cross Finsbury Market tunnel (ection 2.2.6) will have an intermediate shaft position in the basement of Hearn treet ubstation and as such there are options available to either asset replace the existing equipment or to upgrade to a 132/11kV substation fed from the new Osborn treet 132kV switchboard. Option 1: Asset Replacement Poor Condition Transformer and Circuit Breakers ( 2,990k) This option is for the refurbishment of the civil structure and the like for like replacement of the following equipment: 5 x BTH OW409 Dead Tank 66kV Circuit Breakers The old section (18 panels) of AEI QF471 11kV Circuit Breakers 1 x 66/11kV Transformer It should be noted that the like for like replacement of the old section of 11kV switchboard is likely to be challenging for this option. There is no space available on site to construct a new switchboard offline before transferring the feeders across and a temporary switchboard would therefore need to be constructed either in front of the 66kV breakers (thereby restricting access) or out in the public highway (subject to local authority consent). Option 2: Rebuild as a 132/11kV ubstation ( 15,056) - Recommended Phase 1: Decommission horeditch 66kV Breakers and Demolish Building ( 379k) It is proposed to decommission horeditch 66kV before demolishing this area of the site in order to free up space for the substation rebuild. In order to achieve this, it would be necessary to terminate the 66kV double circuit cables from Holloway Grid 66kV and Hackney Grid 66kV directly onto the Hearn treet Transformers as shown in Figure 17 below: Figure 17: Load Flow with horeditch Removed Template v1.1 Page 31 of 52

32 It should be noted that because two of the Hearn treet transformers would be fed from a single breaker at Hackney, only one Hearn treet transformer would remain in service for a fault on one of the Hackney Hearn treet 66kV circuits while the faulted circuit was isolated. Table 12 shows loading data for Hearn treet on 6 June 2013, the hottest day of the year so far at 22 0 C. It can be seen that with the EC and NE winging Feeder Groups fed from Devonshire quare and the N Feeder Group fed via an isolated bus section from Finsbury Market E (through the W Feeder Group), the peak summer transformer loading at Hearn treet is reduced to circa 18.5MVA (The PLE figure has the NE and N Feeder Groups fed from Hearn treet). For the loss of two transformers during summer peak conditions, the site load can therefore be supported by the remaining transformer. This situation could occur for an N-1 cable fault on one of the Hackney circuits as discussed above. There would be 18.5MVA at risk of a second circuit outage while the faulted circuit is isolated. To mitigate this, consideration should be given to double banking one of the Hackney Hearn treet 66kV circuits with an alternative 66kV circuit at Hackney Grid 66kV (suggest the circuit to Hackney 66/6.6kV T2). Feeder Name Feeder No. Power On Amps (6 June 2013) Table 12: Hearn treet with load transferred Transformer winging Feeder Group Loading at Devonshire quare (Amps) Feeder No. Load fed from Finsbury Mkt E through Isolated Hearn t Busbar (W + N Group Amps) Feeder No. Feeder Loading W FINE 32 N W FINE 34 W FINE N W FINE 35 N W FINE 34 C &2 C &2 C &2 N C &2 C &2 EC &2 169 DEVO 27 EC &2 166 DEVO 28 NE &2 131 DEVO 5 EC &2 245 DEVO 26 NE &2 156 DEVO 2 NE &2 224 DEVO 3 BP BP BP BP Feeder Group Loading W Group N Group 1045 A C Group 609 A EC Group NE Group BP Group Transformer Loading FT1 FT2 FT3 Total Amps Total MVA Load at Risk Firm N-2 Risk for N A 580 A 511 A A A 0 A A A 0 A 360 A 1045 A 969 A 1091 A 1045 A 18.5 MVA 20.8 MVA 19.9 MVA 45 MVA 22.5 MVA -4.0 MVA Template v1.1 Page 32 of 52

33 Proposed Running Arrangement 1 (Rejected) Figure 18 below shows the summer 2015 peak load flow on the 66kV system with the Hearn treet loads arranged as indicated in Table 12. For this option there will be two circuits from Hackney Grid 66kV and one circuit from Holloway Grid 66kV terminated directly onto the Hearn treet transformers. The 66kV link from Hackney to Holloway will be broken for this option.. Figure 18: Load Flow with horeditch Removed and Hearn treet Loads Transferred Running Arrangement 1 Note that the two Hackney King Henrys Walk 66kV circuits, which are known to suffer increased gas leak rates when heavily loaded, are loaded to 260A (66% of rating). For an N-1 fault on one of these circuits during summer peak conditions, the remaining circuit would need to carry 520A for switching time. This is in excess of the cyclic rating of the circuit (477A with one circuit in service), but less than the 2 hour emergency rating of 599A. As the load on Hearn treet can be supported by a single transformer, Hearn treet FT1 could be switched out in order to reduce the loading on the remaining Hackney King Henrys Walk 66kV circuit to 460A. For an N-2 fault on the Hackney King Henrys Walk 66kV circuits, two of the four transformers (GT3 & 4) can be transferred to Holloway Grid 66kV (utilising intact capacity) via remote switching, however the other two transformers will remain switched out until an authorised person can attend site to carry out local switching. The limiting factor will be the rating of the two transformers which remain in service until the local switching is carried out, resulting in the loss of the whole site following the fault, reducing to circa a loss of 21MW once remote switching is carried out, with full restoration within 2 hours after local switching. Because this option breaks the 66kV link between Hackney and Holloway, it is rejected in favour of the option below, which facilitates a partial transfer of King Henrys Walk load for an N-1 event, with the trade-off that only two cables (instead of three) can be used to feed the three Hearn treet transformers. Template v1.1 Page 33 of 52

34 Proposed Running Arrangement 2 (Recommended) Figure 19 below shows the summer 2015 peak load flow on the 66kV system with the Hearn treet loads arranged as indicated in Table 12. For this option there will be one circuit from Hackney Grid 66kV and one circuit from Holloway Grid 66kV terminated directly onto two of the Hearn treet transformers, with the third transformer de-energised but double banked onsite by installing a new set of ealing Ends in the FT3 transformer bay with the copper work removed and left on site for use in emergency conditions. The 66kV link from Hackney to Holloway will be maintained for this option, albeit at a reduced capacity of 31MVA with only one cable of the existing two cable per phase arrangement forming the connection. Figure 19: Load Flow with horeditch Removed and Hearn treet Loads Transferred Running Arrangement 2 (Recommended) For an N-1 event on one of the unreliable Hackney King Henrys Walk 66kV circuits, half of King Henrys Walk could then be transferred to Holloway Grid 66kV (fed via Hackney Grid 66kV), without interruption, in anticipation of an N-2 fault, thereby deloading the Holloway King Henrys walk circuit which remains in service and reducing the probability of an N-2 event occurring on these leaky gas filled circuits. As mentioned above, the trade-off is that only two of the three Hearn treet Transformers can be kept in service with this option, but as it is possible to support the entire Hearn treet load on a single transformer (subject to running the system as per Table 12), this is the recommended running arrangement to facilitate the decommissioning of the horeditch 66kV switchgear. Template v1.1 Page 34 of 52

35 Phase 2: Construct a 132/11kV, 2 x 66MVA ubstation and decommission Hearn treet Transformers ( 13,479k) Once the demolition of horeditch and the construction of the spur tunnel and Hearn treet haft are completed, construction of the new substation can commence. Figure 20 below shows the proposed single line diagram for the new substation: Finsbury Market A & C Finsbury Market B & E City Road GP 132kV pare pare pare New Cross GP 132kV Via Osborn treet 132/11/11kV 66.6MVA Existing Hearn treet 11kV witchboard Figure 20: horeditch 132/11kV Proposed ingle Line Diagram Figure 21 below shows the proposed layout for the new substation: Figure 21: horeditch 132/11kV Proposed Ground Floor Layout An 11 panel 132kV switchboard is to be incorporated onsite and used to split Finsbury Market as shown in Figure 20 above. As discussed in ection 3.5, Finsbury Market does not currently comply with Engineering Recommendation Template v1.1 Page 35 of 52

36 P18. This scheme offers an opportunity to correct this, as there is not sufficient space on the Finsbury Market site to do so. It can be seen in the single line diagram above, that the scheme provides 3 spare 132kV connection points for future schemes. It is likely that these will be used when the development of the Bishopsgate Goods Yard, just to the east of Hearn treet, commences. In order to improve resilience, minimise the space usage in the new tunnel/shaft and maximise the thermal headroom available in the tunnel, it is recommended that the circuit connections from City Road GP and those to Finsbury Market A & C are made by looping in/out of horeditch ubstation from the existing City Road Finsbury Market circuits. This will require 6 x 132kV circuits to be installed along the 300m cable route shown in red below: Existing Proposed Figure 22: City Road horeditch Finsbury Market Proposed 132kV Route The connections from Osborn treet and to Finsbury Market B & E will be via the new tunnel and Hearn treet haft. The option of an alternative shaft position beneath the proposed 132kV switchgear at horeditch is also under investigation. This option would allow for a larger shaft to be constructed once the existing substation is demolished, as the floor slab in the Hearn treet basement restricts the shaft diameter achievable. In addition there are potential savings in construction costs as there is restricted working space within the Hearn treet basement and as the space is not suitable as Tunnel Boring Machine (TBM) drive site, the TBM would need to be assembled in a junction chamber from within the tunnel, with access via the Finsbury Market shaft. horeditch however, is likely to be suitable as a drive site once demolished. Once the construction of the substation is completed, then the existing Hearn treet 11kV switchboard is to be transferred onto the new 132/11/11kV transformers in order to facilitate the decommissioning of the existing 66/11kV transformers. Note that there are only three incomers on the existing 11kV switchboard and so one set of the windings of the dual secondary transformers will be unutilised during this construction phase. Once the 66/11kV transformers are decommissioned, the Hackney Holloway 66kV connections are to be reestablished. It is recommended that the circuits are returned to their double banked arrangement at Hackney Grid. Phase 3: Replace Hearn treet AEI QF471 11kV Circuit Breakers ( 1,577 - programmed for early ED2) Template v1.1 Page 36 of 52