Guidance Document Traditional Planning Considerations for Power Electronics Devices Guidance Document Traditional Planning Considerations for Power Electronics Devices COPYRIGHT NOTICE Diagrams in this document and appendices from our London Power Networks licensed area are reproduced by permission of Ordnance Survey on behalf of HMSO. © Crown copyright and database right 2014. All rights reserved. Ordnance Survey Licence number 100019826. Data has been added to the Ordnance Survey base map; all proprietary rights in such additional data are and shall remain the exclusive property of © London Power Networks plc or Eastern Power Networks plc or South Eastern Power Networks plc each being a distribution licensee under section 6(1)(c) of the Electricity Act 1989 for the relevant distribution services area as that term is defined in such licensee’s distribution licence. All rights in such data reserved. Diagrams in this document and appendices from our South Eastern Power Networks licensed area are reproduced by permission of Ordnance Survey on behalf of HMSO. © Crown copyright and database right 2014. All rights reserved. Ordnance Survey Licence number 100019450. Data has been added to the Ordnance Survey base map; all proprietary rights in such additional data are and shall remain the exclusive property of © South Eastern Power Networks plc or London Power Networks plc each being a distribution licensee under section 6(1)(c) of the Electricity Act 1989 for the relevant distribution services area as that term is defined in such licensee’s distribution licence. All rights in such data reserved. LEGAL NOTE 1. UK Power Networks does not warrant that the information provided to you is correct. You rely upon it at your own risk. 2. UK Power Networks does not exclude or limit its liability if it causes the death of any person or causes personal injury to a person where such death or personal injury is caused by its negligence. 3. Subject to paragraph 2 UK Power Networks has no liability to you in contract, in tort (including negligence), for breach of statutory duty or otherwise for any loss, damage, cost, claims, demands, or expenses that you or any third party may suffer or incur as a result of using the information provided whether for physical damage to property or for any economic loss (including without limitation loss of profit, loss of opportunity, loss of savings, loss of goodwill, loss of business, loss of use) or any special or consequential loss or damage whatsoever. 4. This plan has been provided to you on the basis of the terms of use set out in the covering letter that accompanies this plan. 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Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 2 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Abbreviations ACB BAU DINIS DNO DNV ENA FUN-LV GIS HV LCNF LPN LV MSS NOP PED RTU SDRC SPN UKPN Air Circuit Breaker Business As Usual Distribution Network Information Systems Distribution Network Operator Distribution Network Visibility Energy Networks Association Flexible Urban Networks – Low Voltage Geographical Information Systems High Voltage Low Carbon Networks Fund London Power Networks Low Voltage Main Substation - LPN term for Primary Substation (secondary voltage of 11kV) Normal Open Point (for LV systems – either a Link box or LV distribution board) Power Electronics Device Remote Telemetry Unit Successful Delivery Reward Criteria South Eastern Power Networks UK Power Networks UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 3 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Contents 1 2 3 4 5 6 7 8 9 10 Purpose ............................................................................................................................................6 Planning Considerations ..................................................................................................................6 2.1 UK Power Networks Planning Processes ............................................................................6 2.2 Traditional Planning Systems ...............................................................................................6 2.3 Network Analysis/Studies ...................................................................................................12 Business As Usual Comparison Case Studies – London Sites .....................................................16 LPN Method 1: Albert Embankment Camelford House North (90008) – Radial Network .............17 4.1 Connection Driven Reinforcement – Planners Log ............................................................17 4.2 Load Growth Driven Reinforcement ...................................................................................22 4.3 Proposed FUN-LV Method 1 ..............................................................................................23 LPN Method 2: Piccadilly Ritz Hotel (31529) – Interconnected Network ......................................26 5.1 Connection Driven Reinforcement – Planners Log ............................................................26 5.2 Load Growth Driven Reinforcement ...................................................................................29 5.3 Proposed FUN-LV Method 2 ..............................................................................................30 LPN Method 3: Shaftesbury Ave 125 (24410) – Interconnected Network ....................................34 6.1 Connection Driven Reinforcement – Planners Log ............................................................34 6.2 Load Growth Driven reinforcement.....................................................................................38 6.3 Proposed FUN-LV Method 3 ..............................................................................................39 Trial Site Case Studies – Brighton Sites ........................................................................................42 SPN Method 1: Regent Hill (523461) – Radial Network ................................................................42 8.1 Example FUN-LV Method 1 ................................................................................................42 SPN Method 2: Duke Street (523338) – Radial Network ..............................................................44 9.1 Example FUN-LV Method 2 ................................................................................................44 SPN Method 3: New Road (523230) – Radial Network ................................................................47 10.1 Example FUN-LV Method 3 ................................................................................................47 Table of Figures Figure 1- ENMAC/PowerOn Screenshot of the LV Network ................................................................... 7 Figure 2 - Distribution Network Visibility Geographical Map Screenshot ................................................ 8 Figure 3 - Distribution Network Visibility Utilisation Screenshot .............................................................. 9 Figure 4 – SPN NETMAP Screenshot ................................................................................................... 10 Figure 5 - WinDebut Screenshot ........................................................................................................... 11 Figure 6 - DINIS Screenshot ................................................................................................................. 12 Figure 7 - Google Maps View – Albert Embankment Camelford Hs N ................................................. 17 Figure 8 – LV Geoview – Albert Embankment Camelford House N ..................................................... 18 Figure 9 – DNV Utilisation– Albert Embankment Camelford House N (90008) .................................... 19 Figure 10 – DNV Utilisation– Albert Embankment-Tintagen House (90007) and ................................. 20 Figure 11 – NETMAP Webview– Albert Embankment Camelford House North ................................... 21 Figure 12 – Proposed PED Solution – Albert Embankment Camelford House North........................... 23 Figure 13 – Method 1 Variant – no link box switches ............................................................................ 23 Figure 14 – Method 1 Variant – with link box switches ......................................................................... 24 Figure 15 –Method 1 LV Circuit Breakers ............................................................................................. 24 Figure 16 - Google Maps View – Piccadilly Ritz Hotel .......................................................................... 26 Figure 17– LV Geoview- Piccadilly Ritz Hotel ...................................................................................... 27 Figure 18 – DNV Utilisation – Piccadilly Ritz Hotel ............................................................................... 27 Figure 19 – HV Geoview – Piccadilly Ritz Hotel ................................................................................... 29 Figure 20 – DINIS Network View – Piccadilly Ritz Hotel ....................................................................... 30 Figure 21 – Proposed PED Solution – Piccadilly Ritz Hotel .................................................................. 31 UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 4 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Figure 23 – Method 2 general arrangement .......................................................................................... 32 Figure 22 – Method 2 Free Standing Cabinet ....................................................................................... 32 Figure 24 - Google Maps View – Shaftesbury Ave 125 ........................................................................ 34 Figure 25 – LV Geoview – Shaftesbury Ave 125 .................................................................................. 35 Figure 26 – DNV Utilisation– Shaftesbury Ave 125 .............................................................................. 36 Figure 27 – HV Geoview – Shaftesbury Ave 125 .................................................................................. 37 Figure 28 – DINIS Network View – Shaftesbury Ave 125 ..................................................................... 38 Figure 29 – Proposed PED Solution – Shaftesbury Ave 125 ................................................................ 39 Figure 30 – Method 3 general arrangement .......................................................................................... 40 Figure 31 – Method 3 Control Panel and Power Electronics Panel (1 of 3) .......................................... 40 Figure 32 – Traditional Planning for PED Solution – Regent Hill .......................................................... 42 Figure 33 – Traditional Planning for PED Solution – Duke Street......................................................... 44 Figure 34 – New Cable Installation Boyces’ Street ............................................................................... 46 Figure 35 – Traditional Planning for PED Solution – New Road ........................................................... 47 UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 5 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 1 Purpose The purpose of this guidance document is to outline traditional planning processes and considerations, summarising how these relate to the connection of PED on urban LV networks. PEDs provide a sophisticated method of interconnecting LV networks and enabling access to the latent/spare capacity from neighbouring substations. During a trial rollout of these devices it is necessary to understand the capability of current planning systems in context of device selection, design and installation. These considerations are detailed as evidence in accordance with the Flexible Urban Networks – Low Voltage (FUN-LV) project, a Low Carbon Networks Fund Tier 2 project. This document concerns urban LV networks and accordingly focuses only on underground cables networks and not overhead line networks. Radial (SPN/LPN) and interconnected (LPN only) underground networks are referenced being that both network types are present within the FUN-LV trial areas. 2 Planning Considerations Many business as usual planning considerations for typical planning solutions are also relevant when selecting, designing and installing PEDs. These include costs, longevity, security/quality of supply, fault level, space constraints, planning and installation time and planning permission/consent. The following sections on traditional planning systems and network analysis/studies will explore these considerations in more detail as well as discussing their application to connecting PEDs. Examples of these considerations are investigated further in Section 3. 2.1 UK Power Networks Planning Processes The UK Power Networks distribution planning department are responsible for planning work at voltages of 11kV and below on the network, typical undertakings include customer connection referrals, reinforcement and asset replacement works. Reinforcement of the network can be initiated from each of these various areas i.e. requirement to connect a new customer on an overloaded network, requirement to reinforce due to natural load growth and opportunistic reinforcement due to other required works such as new asset installations. Traditional reinforcement could involve replacing transformers to an increased capacity rating, replacing cables to a higher current rating or building a new secondary substation, this is dependent on the critical limitation of that network area. PEDs can be considered as a method of deferring the traditional reinforcement for an appreciable period of time (up to 8 years). As with any reinforcement solution, selection will be based on providing the ‘minimum cost solution’ taking into account the particular network requirements, cost efficiency and time/space constraints specific to a given case. 2.2 Traditional Planning Systems Several tools/applications are currently used to analyse the LV network in the context of planning work, these include ENMAC/PowerOn, DNV, NETMAP, WinDebut and DINIS, each of these is described below. An additional tool being trialled by the project (DPlan) is not currently used as part of the business as usual planning systems.) ENMAC/PowerOn This software displays the network connectivity at EHV, HV and LV levels. The LV ‘Geoview’ geoschematics, as shown in Figure 1, are used by distribution planners to observe existing cable UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 6 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices routes, cable size/type, secondary substations and link boxes, network configuration, basic operational information/status, building outlines, customer location and certain items of asset information. This system can enable the selection of substation sites for PEDs by displaying the LV connectivity and subsequently potential routes for power transfer between substations. The power transfer might utilise sharing between two or three substations and potential LV mains between them. These geoschematics can also indicate what installation arrangements may be possible in order to gain the required power transfer e.g. retrofitting link boxes or cross jointing between LV mains. Due to PEDs being capable of remote network reconfiguration, a representation of the devices and networks would need to be present in the connectivity model. Under the current system, there is no automated visibility of the LV network configuration i.e. switching operations in link boxes and substation LV distribution boards must be recorded into the system manually, however, PEDs are capable of relaying such information. The ENMAC/PowerOn connectivity diagrams will be utilised to assess the feasibility of connecting secondary substations via the LV network i.e. link boxes or LV distribution boards, as well as marking network boundaries (primary substation/feeder group/block). However, there is a limitation in automatically tracing LV feeders to their donor substations (although this functionality is currently present in the HV diagram), and this would better facilitate viewing connections in dense networks. Automatic LV feeder tracing would save time in planning BAU works as well as planning for PEDs. Transformer utilisation data is available (for substations with RTUs) in graph format as well as data tables, however, coordinating the desired data into this format is complex. Figure 1- ENMAC/PowerOn Screenshot of the LV Network DNV (Distribution Network Visibility) Tool The DNV Tool is used to gather and display data, on demand, from a number of disparate databases, to obtain a better representation of how the network is performing. DNV is applied by planners both as a geographical map of the network assets (see Figure 2) as well as an indicator of asset utilisation (maximum demand) and load profiles (see Figure 3). Data is communicated from RTUs installed in the primary and secondary substations to a server database and illustrated in a user friendly, discernable visual format in the DNV Tool. This tool has a particular relevance in planning new customer points of connection as it can display secondary substations according to their available capacity using a colour key. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 7 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices This tool can be used to identify overloaded secondary substations and recognise load profiles (residential/ commercial/night). These two factors are critical in selecting and matching sites that would benefit from installing PEDs. The utilisation view (shown in Figure 3) is not only used to identify the substation that would become overloaded and require power transfer but also the load profiles of potential donor substation nearby. By measuring the extent of overloading, it is possible to select a suitable Method capable of transferring an amount of power e.g. a multi terminal device is capable of transferring more capacity than a dual terminal PED. Additionally these load profiles illustrate the time and duration for which the maximum demand typically occurs, this information is considered in designing the control processes of the PED. The implementation of this tool largely depends on the installation of RTUs in secondary substations and the availability of historical data. For example in LPN, 54% of secondary substations have RTUs as compared to only 26% in SPN. Moreover, the RTU data in SPN only reflects the HV network (i.e. measurement current transformers around HV cables) and cannot be captured retrospectively (only illustrates live readings). In addition to RTU data (where available), an asset management system (Ellipse) is used by LPN and SPN to log the MDI (Maximum Demand Indicator) readings through a regular programme of substation inspections. Figure 2 - Distribution Network Visibility Geographical Map Screenshot UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 8 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Figure 3 - Distribution Network Visibility Utilisation Screenshot NETMAP This application provides a scaled geographical map of the LV and HV cable routes. There are various layers that can be superimposed onto the Ordnance Survey background map, providing more detailed information on cable joint locations, cross sections for cable positions in the ground, substation position, LV service cables/SRC (service record cards), link box locations, building outlines and road/pavement layouts. These layers include older hand sketched raster-based drawing plans as well as some vectorised digital information e.g. some cable routes. An example of this overlay is illustrated in Figure 4 with the vectorised cable routes represented as blue lines and raster drawings/annotations in grey. The business typically uses NETMAP drawings (commonly 1:500 scale) when assessing practicalities of works (particularly underground). Although there is no substation equipment information and no utilisation information available, this application provides detailed cable asset information, including size, type, positioning, ducting and age. In terms of planning the installation of PEDs, these NETMAP drawings are important in verifying the cable information shown in the LV ENMAC/PowerOn connectivity diagram ‘Geoview’ and customer connection points with LV services information. The scaled map can provide a more refined outline of potential installation sites, such as highlighting larger secondary substations (potential for multi terminal device) and planning connections to the LV mains (retrofitting link boxes or using dual terminal device). Whilst the mapping continues to combine various layers of network information, there are areas of potential inconsistency and outdated information. Within the LPN network, only new additions to the network are being incorporated as vectorised drawings and therefore the raster images are often used, however, in SPN the full LV network can be examined in the vectorised format. Considering that this application is widely used across the business, it would be expected to include objects representing PEDs. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 9 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Figure 4 – SPN NETMAP Screenshot WinDebut WinDebut is primarily used in the SPN planning department to model single LV networks, providing volt drop, earth loop impedance and predicted fault currents. It does not allow for import of data links from other systems, rather it relies upon the designer to build the network based upon information from other systems such as Netmap and customer usage information. Typically WinDebut is used to perform basic studies on networks with supply quality issues, and longer feeders with undersized cables/conductors, an example study is shown in Figure 5. It allows for the modelling of customers by means of standard load profiles which can be scaled to customer annual usage, as well as motors, welders, and from version 3.1 the modelling of various forms of LV connected generation, photovoltaic cells etc., on the network. Due to the lack of network information in WinDebut, building network models and apportioning customer usage information is a time consuming exercise for planners. Additionally the accuracy of the model is wholly dependent on the estimations and assumptions that are adopted by the planner rather than being a direct reflection of the network. This flexibility is useful for modelling simple direct services, rural overhead line networks and creating local networks from scratch such as new housing estates. However, there are limitations on applying this software to urban networks, encompassing implications to the wider network and geographical referencing. As it does not reflect the existing network, WinDebut has limited functions that will assist in selecting and installing the PED. Utilising WinDebut for designing networks including PEDs will also prove to be difficult as Windebut can only model from a secondary substation to the open point or customer, it does not allow for the modelling of interconnected LV networks or the Power Transfers which would occur. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 10 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Figure 5 - WinDebut Screenshot UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 11 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices DINIS (Distribution Network Information Systems) The DINIS application is primarily used in the LPN planning department (not used in SPN or EPN) for its network modelling capabilities. An output from the DINIS model network connectivity is reflected in ENMAC/PowerOn, hence DINIS contains network information to conduct load flow analysis (including voltage drop and network current), fault level analysis and model protection operation. Individual feeder groups can be loaded from a master network for local analysis, a single LPN feeder group view is shown in Figure 6, HV and LV cables represented in red and grey respectively. The LPN planning department only typically run fault level analysis in DINIS for connections involving generation, starter motors or where transformer capacity is upgraded in interconnected systems. The Fault Study Package (FSP) is also available as an add-on within DINIS, which is used for large network reinforcement planning schemes. This system can be utilised in planning PED selection in a similar way to ENMAC/PowerOn. The LV connectivity diagram is geographical and demonstrates potential routes of power transfer between nearby substations. The diagram has a representation of link boxes and can therefore be used to plan potential capacity sharing across these open points (retrofitting link boxes or using dual terminal device). DINIS has additional facility through network modelling, which can provide a better understanding of the existing load flows and fault level in the network. There is the capability within DINIS to model interconnected systems, however, this can be a time demanding process i.e. before retrieving results the model requires load information to be imported/manually input and time allowed for running the analysis. Using the current DINIS modelling function to conduct load flow and fault level studies on networks involving PEDs would prove difficult as no function has yet been created that can represent a specified power transfer (as opposed to one derived from system impedance) and also one that varies in time (as opposed to a snapshot of the current demand). Figure 6 - DINIS Screenshot UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 12 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 2.3 Network Analysis/Studies The following section details typical considerations involved in the planning process for connecting new customers on to a fully loaded network. Comparable considerations apply when planning reinforcement of the network following natural load growth (driven by the DNO). These contexts can equally demonstrate the planning considerations that are important in the process of selecting, designing and installing of PEDs. LV Connection Options To accommodate new customer connections on an LV network with a transformer capacity limitation, there are a variety of options that would be considered as part of the business as usual approach. The viability of each option will depend on the details of the network and providing the minimal cost solution. These costs may include materials (cables, transformer, substation housing), contractor (for civil works i.e. excavation, reinstatement and traffic management), labour (jointers, field engineers) and other (legal). Examples of traditional LV connection options are listed below. Radial Network Options: Transfer transformer load – Move the Normal Open Point (NOP) (closer to the overloaded substation) to reduce the transformer load, i.e. the load shifts to a neighbouring transformer. Using existing link boxes and LV distribution boards. N.B. This could apply to any LV main from the substation including the one intended for the new connection. Transfer transformer load – Create NOP (closer to overloaded substation) via the installation of a new link box. Alternative point of connection – Connect new customer on to an LV main being fed from a different substation (not overloaded). This would often be a dedicated service and would likely increase the distance of new cable installation and road excavations. Increase transformer rating – Replace the overloaded transformer with a higher rated transformer. New substation – Build a new substation i.e. new transformer to feed the new customer. Interconnected Network Options: Alternative point of connection – Connect new customer on to a more optimal LV main within the interconnected network. This would also increase the distance of the new cable installation and road excavations. Increase transformer rating – Replace the overloaded transformer with a higher rated transformer. New substation - Build a new substation i.e. new transformer to feed the new customer. If cable capacity is the limitation for making new connections, similar options are considered including transferring load, connecting to alternative LV mains with capacity or upgrading overloaded cable to a higher rated cable. Sharing capacity in a radial network via the insertion of links/fuses (in a link box/LV distribution board) is not typically considered under permanent planning solutions. This is used for switching under fault scenarios, after which the network should be returned to the configuration as planned. PEDs can contribute to the portfolio of already available solutions mentioned above considering their respective costs and varied applicability. The implementation of PEDs will particularly target cases where expensive solutions such as a new substation or a combination of alternative point of connection and increasing the transformer rating are required. This capability is achieved through the transfer or sharing of capacity between neighbouring substations. The different PEDs available can cater to meet a variety of network scenarios such as differing connection load requirements (sharing between two or three substations) or space constraints (choice of pavement or substation UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 13 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices installations). PEDs additionally provide flexibility in network reconfiguration being that they have remote operability as well as automated operation and can therefore offer dynamic network management. In already interconnected networks, PEDs can provide benefits such as reducing and/or constraining fault level, controlled power transfer (as opposed transfer based on to impedance), load unbalance/power factor/harmonics correction and capacity sharing across network boundaries. Substation Lease Requirements Another factor to recognise for new connections is the condition of the lease for the property containing a substation. This is evaluated through enquiries to the Operational Property and Consents department, who are responsible for the protection of existing assets and the acquisition of new consents as necessary, so as to minimise business risk. Cable Capacity For new LV customer connections exceeding 140kVA, the planning department must consider cable size/type (and associated cyclic ratings) as well as the existing load already connected to the LV cable. This information will give an indication as to whether the cable being considered has available capacity to accommodate the new customer connection. This LV cable utilisation data cannot currently be acquired using RTU data as the current measurements relate to the overall transformer load and not individual LV cable mains connected to the substation LV distribution board. As mentioned above, cable size/type information can be found on DINIS (equivalent with data in ENMAC/PowerOn) as well as NETMAP. Associated cyclic ratings are also available on these applications, however, these are not an accurate reflection of the cable rating used by the business. Although, high level guidance can be acquired from ENA Engineering Recommendation P17 – ‘Current Ratings for Distribution Cables’, the effects of numerous parameters (including ground type, adjacent cables, ducting arrangements) are not quantified in detail. Moreover, these ratings are based on cyclic load profiles. The UK Power Networks Engineering Design Standard EDS 02-0049 – ‘Calculation of DINIS Cable Ratings’ provides cable ratings for summer and winter seasons as well cyclic and continuous load profiles. This standard includes the representative cables ratings demonstrating the effects of ground type, adjacent cables and ducting arrangements, although these are not comprehensive. Transfer profiles resulting from use of PEDs may be similar or very different to typical load profiles and may need continuous cable ratings to be used. The existing load connected to LV cables is typically estimated through use of current readings (measurement devices include tong testers/ammeters e.g. Redskye RSK 2000PA Rogowski Coil). These current readings are taken instantaneously rather than over extended measurement durations, this is due to time constraints within the standard license agreement. When planning the connection of PEDs to the network, power flow studies would be necessary to ensure that the required transfer/sharing of capacity between substations can be accommodated by the LV main cable bridging the capacity exchange. Defining a practical magnitude and duration of the power transfer will ensure that the appropriate LV cables will be able to carry the current without having an impact on their condition. As mentioned above, a tool would be required to conduct power flow studies and fault analysis taking into account the dynamic characteristic of the capacity transfer/sharing and network reconfiguration using PEDs. As part of the FUN-LV project, studies will be conducted to model PEDs using the software DPlan. As well as using network modelling, the installation of LV network monitoring in conjunction with PEDs would benefit LV cable loading visibility. This would allow control systems to actively manage the loading of cables by evaluating time based cable loading information and cable rating data. Fault Level Analysis As well as analysing the additional load of new connections during normal running, fault analyses are carried out in cases of generation, starter motors and increased transformer ratings within an UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 14 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices interconnected network. These studies aim to ensure that the fault level (prospective short circuit current) is within the ratings of protection equipment and that the operation is coordinated appropriately. By installing PEDs, capacity sharing/transfer can be achieved without increasing the fault level of that network (as it would through traditional interconnection). This is due to the functionality of the PED which does not allow the transfer of fault current, the device will only transfer a specified amount of current (according to its programmed instructions). This feature is also important in protecting the device itself as transistors within the inverter bridge have a low thermal inertia. The PED can also be programmed to stop current transfer altogether if it detects a collapse in voltage, as would occur in a typical fault. Further fault studies will be required, using appropriate software tools, to ensure that the PED operation complements existing network protection, considering scenarios such as LV distribution board faults and HV phase-phase and phase-to-earth faults. This reaffirms the necessity of a tool to conduct power flow studies and fault analysis taking into account the dynamic characteristic of the capacity transfer/sharing. Supply Restoration Within the UK Power Networks distribution planning department, supply restoration is analysed for HV network planning only. Effective supply restoration planning ensures practical and fast restoration of as many customers’ supplies as possible following a power outage. On the LV network supply restoration would involve temporarily reconfiguring the LV network open points (moving/creating NOP via link boxes and LV distribution boards) whilst the LV fault is repaired. The number of customer supplies restored depends on how the network can be sectionalised i.e. groups of customers on a LV cable are separated/isolated between LV open points. On radial networks, supplies can be restored by isolating the faulty LV leg (e.g. removing links) and back feeding customers from an adjacent healthy LV feeder (e.g. inserting links/fuses into a NOP). A well planned network should have sufficient LV network open points available to segregate sections of network (groups of customers), this will enable a larger group of customers to be isolated from the faulted section and have their supplies restored from an adjacent healthy LV feeder. However on an interconnected network customer supplies are already connected in parallel (multiple substations supplying the same customers), and therefore customers might not lose power supply in the event of a fault (this is dependent on fault type). Effective planning should minimise the risk of customer load allocation (number of customers) exceeding the ‘hold up’ capacity of the donor substations. Hold up capacity in this case referring to the ability of a substation to support the load/customers on an adjacent network, following a loss of normal supply provision. Further information on LPN Interconnected Network and Enhanced Meshing is described in the UK Power Networks Business Plan Annex 9: Smart Grid Strategy. PEDs can complement supply restoration on interconnected networks through capabilities such as sharing capacity across network boundaries (primary substation/busbar/group) and supporting network corners (areas furthest from hold up supply). PEDs being installed on interconnected networks would be expected to complement the existing hold up arrangements of a network system. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 15 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 3 Business As Usual Comparison Case Studies – London Sites The following business as usual comparison case studies illustrate the traditional reinforcement options at specific FUN-LV trial sites being selected for the installation of PEDs on the LPN network. These case studies consist of traditional reinforcement scenarios driven by a hypothetical customer connection request or natural load growth, followed by the proposed FUN-LV trial solution. This analysis will demonstrate the planning considerations as well as illustrative cost estimates for each reinforcement solution. There are three LPN case studies in this section, these include an example for each of the three Methods in the FUN-LV project. Following PED network trials, actual costs will be used to address the economic feasibility and practicality of meshed networks using these Methods, as well as the suitability dependent on factors such as location. Table 1 illustrates a summary of the example business as usual solutions for each case study and the potential savings gained through use of the proposed FUN-LV trial solution. These savings are attributed against the total costs for both the customer connection and load growth reinforcement triggers. Example Type of Network Albert Embankment Camelford House North Radial BAU Solution FUN-LV Connection Load Growth Method (Customer) (DNO) Transformer Upgrade Transformer Upgrade Total Savings Connection Load Growth (Customer) (DNO) 1 Approx. £43,000* Approx. £12,000* £58,000 to £88,000 plus land costs Approx. -£24,000 (negative) Piccadilly Ritz Hotel Existing Meshed New Substation New Substation (Interconnected) 2 £109,000 to £139,000 plus land costs Shaftesbury Avenue 125 Existing Meshed New Substation New Substation (Interconnected) (in existing site) (in existing site) 3 Approx. £36,000 * This FUN-LV Method 1 solution uses only one spine circuit and no link box switches, the variant with link box switches will reduce the above savings by approximately £12,000. The shared capacity for all Method 1 solutions is dependent upon network impedance. Table 1 – BAU Comparison Costs Summary UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 16 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 4 LPN Method 1: Albert Embankment Camelford House North (90008) – Radial Network 4.1 Connection Driven Reinforcement – Planners Log To represent a connection driven reinforcement scenario a hypothetical request was received from the customer enquiry system for 200kVA to be provided at 89 Albert Embankment, Lambeth, SE1. Figure 7 - Google Maps View – Albert Embankment Camelford Hs N UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 17 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Figure 8 – LV Geoview – Albert Embankment Camelford House N UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 18 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Looking at the Geoview LV network, the closest secondary substation is Albert Embankment Camelford House North (90008) with a transformer rated at 500kVA. Nearby substations include Albert Embankment-Tintagen House (90007) – 500kVA, Albert Embankment 93 (90005) – 500kVA and Albert Embankment Camelford House South (90009) – 2 x 500kVA. Figure 9 – DNV Utilisation– Albert Embankment Camelford House N (90008) Looking at the utilisation data using DNV for Albert Embankment Camelford House North with a transformer rated at 500kVA, the maximum demand on Albert Embankment Camelford House North already exceeds an acceptable level, exceeding 600kVA. This is above 120% of the name plate rating (600kVA), which is the upper limit that transformers are allowed run at for short periods of time in radial networks. In order to reduce the overloading on this transformer it might be possible to transfer load to a neighbouring substation by moving NOPs. Observing the LV network on Geoview there are multiple potential NOPs that can be moved, which would involve the neighbouring substations (90005/90007/90009). However, as the majority of load connected to these other substations are direct services, transferring these sections of network (by moving NOPs) will not transfer significant load to alleviate substation 90008. Therefore, the capacity for the new connection can be made available either by upgrading the transformer at Albert Embankment Camelford House North (90008) or by connecting to one of the neighbouring substations, the former option is likely to be being more expensive. In both cases this 200kVA connection request will need to be via a direct service rather than a passing LV main as any additional load would be likely to exceed the cable rating (200kVA is approximately 300A at low voltage). Other secondary substations in close proximity to supply the new direct service would be Albert Embankment-Tintagen House (90007) – 500kVA or Albert Embankment Camelford House South (90009) – 2 x 500kVA. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 19 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Figure 10 – DNV Utilisation– Albert Embankment-Tintagen House (90007) and Albert Embankment Camelford House South (90009) UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 20 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Customer Location Selected Substation Available Duct Route (empty circle) Figure 11 – NETMAP Webview– Albert Embankment Camelford House North UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 21 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Looking at the utilisation data from DNV for Albert Embankment-Tintagen House (90007) and Albert Embankment Camelford House South (90009). The maximum demand on Albert EmbankmentTintagen House (90007) is approximately 330kVA in 2013, therefore there is less than 200kVA spare capacity (500kVA transformer). The maximum demand on Albert Embankment Camelford House South (90009) is below 300kVA, therefore there is more than 700kVA spare capacity (2 x 500kVA transformers). Additionally, observing the scaled NETMAP view in Figure 11, the cable route from Albert Embankment Camelford House South (90009) is shorter and would therefore require less excavation than from Albert Embankment-Tintagen House (90007). The approximate length for this direct service would be 80m. It is also apparent that there is an old duct route between the two substations, however, it is unlikely that this could be utilised for the length of the direct service. Due to items stated above, it would be proposed to the customer that the transformer in Albert Embankment Camelford House North (90008) is replaced with a 1MVA rated transformer and a direct service is installed for the customer at 89 Albert Embankment to cater for the 200kVA request. This is provided that an additional service/fuse-way can be feasibly connected to the existing LV distribution board or by extending the board. This arrangement would provide an additional 200kVA spare capacity to the network as well as providing the customer with 200kVA under the minimum cost scheme. 4.2 Load Growth Driven Reinforcement This area of network is configured as a radial system and therefore the transformer could be allowed to run at 120% of its capacity (600kVA) for short periods of time. From the utilisation data shown in Figure 9, the maximum demand is already above 600kVA and is therefore exceeding this limit. The transformer could be upgraded by replacing the original 500kVA rated transformer to one with either an 800kVA or 1MVA rating. Reinforcement Options: Transfer transformer Load – Move/create NOP (closer to the overloaded substation). As the majority of load connected in this area of network is direct services, transferring these sections (by moving NOPs) will not transfer significant load to alleviate substation 90008 Increase transformer rating – Installing an additional 500kVA transformer would increase the 120% rating to 1.2MVA. This would involve retaining the existing old 500kVA (potential asset condition issues) and therefore more space is required to hold both transformers. Increase transformer rating – Installing an 800kVA transformer replacement would increase the 120% rating to 960kVA. Increase transformer rating – Installing a 1MVA transformer replacement would increase the 120% rating to 1.2MVA. New substation – Build a new substation and transfer network load/direct services from old substation onto a new installed network substation. The proposed planning solution in this case would be to replace the original 500kVA transformer with an 800kVA transformer (costs for an 800kVA transformer are comparable to that of a 500kVA transformer). This option should provide adequate capacity for the existing connections at Albert Embankment Camelford House North (90008) as well as spare capacity to cater for new connections and future load growth. The new transformer will utilise a comparable footprint to the original. Based on load estimates for this substation, the latter options of installing a 1MVA transformer or a new substation are likely to be unnecessary. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 22 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 4.3 Proposed FUN-LV Method 1 In this area there is spare capacity of 170kVA at Albert Embankment-Tintagen House (90007) and 700kVA at Albert Embankment Camelford House (90009), over capacity of 100kVA at 90008 and therefore a total surplus of 770kVA. This spare capacity can be utilised for sharing capacity through meshed networks if load profiles are complementary. As part of the FUN-LV project, this site was selected for the installation of Method 1 comprising of LV circuit breakers at both substations with no link box switches required. These LV circuit breakers allow automated operation and may enable a capacity transfer of up to 200kVA between Albert Embankment Camelford House North (90008) and Albert Embankment Camelford House South (90009). Figure 12 – Proposed PED Solution – Albert Embankment Camelford House North In the configuration proposed, the LV circuit breakers will replace fuses on the LV distribution board connecting both substations. The circuit will be run in a meshed arrangement by closing the existing NOP currently at Albert Embankment Camelford House South (90009) and will allow the remote operation of LV circuit breakers at both ends. Figure 13 demonstrates arrangements for the existing network configuration and proposed FUN-LV Method 1 in this example, which does not require use of a remote controllable link box. Figure 13 – Method 1 Variant – no link box switches UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 23 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Another variant of FUN-LV Method 1 being used at other trial sites includes the installation of a remote controllable link box (containing switches). The diagram in Figure 14 demonstrates arrangements for the existing network configuration and proposed FUN-LV Method 1 for this type of trial site. In this arrangement there are additional equipment costs as well as civil works associated with replacing and jointing the new link box. The benefits of this variant include additional flexibility to configure the LV network as necessary for example it can be run as two shorter radial circuits, one long radial circuit, one parallel circuit or sectionalised in the event of a fault. The photo in Figure 15 shows one set of three LV circuit breakers installed on an LV distribution board. Figure 14 – Method 1 Variant – with link box switches Figure 15 –Method 1 LV Circuit Breakers UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 24 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices FUN-LV Method Comparison and Considerations Costs – In comparison with the business as usual solutions, the PED costs (approx. £14,000) are less than both the connection driven reinforcement (customer – approx. £49,000, DNO – approx. £8,000) and the load growth driven reinforcement (approx. £26,000). Longevity – Current estimates for the lifetime of the PED equipment is under 10 years, therefore it is providing a temporary solution by delaying traditional reinforcement. A typical transformer life time would be 40 years. Security/Quality of Supply – The PED capability includes an automated response in the event of a fault as well as remote switching. In this example as there is no link box between the two sets of Remote Controllable Circuit Breakers there is no decrease response time in the event of restoring a fault on this circuit. Traditionally fuses would have operated to clear the fault. Equipment Size – The LV circuit breakers are equivalent to the dimensions of a fuse carrier with a deeper housing unit. PED Location – The LV circuit breakers would be installed on the LV distribution board, the power data bus below the fuse carriers and the gateway is attached to a wall within the substation. Planners Time – The PED solution would require additional LV load flow studies and fault level studies to ensure that sufficient capacity is being shared. However, the majority of planning for this radial network is comparable to traditional solutions . In addition the Remote Controllable Circuit Breakers have an inhibit function preventing it from attempting to clear a fault which is close to the substation. The inhibit zone is a function of circuit impedance and is determined to be the point where the fault current is calculated to be less than the break rating of the power electronics thyristor of 6kA. Installation Time – The Method 1 equipment would be delivered and installed within 1 day, whereas BAU solutions (transformer replacement) could require 3-4 days. Planning Permissions/Consent – As Method 1 equipment is internal to the existing substation no planning permissions would be required. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 25 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 5 LPN Method 2: Piccadilly Ritz Hotel (31529) – Interconnected Network 5.1 Connection Driven Reinforcement – Planners Log To represent a connection driven reinforcement scenario a hypothetical request was received from the customer connection gateway for a further 240kVA to be provided at Piccadilly Ritz Hotel, 150 Piccadilly, London, W1J. Figure 16 - Google Maps View – Piccadilly Ritz Hotel UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 26 of 49 Location 1.0 MVA Guidance Document 800 kVA Traditional Planning Considerations for Power Electronics Devices 1.0 MVA Figure 17– LV Geoview- Piccadilly Ritz Hotel Looking at the Geoview LV network, the closest secondary substation is Piccadilly Ritz Hotel (31529) with a transformer rated at 1MVA. Nearby substations include Arlington Street 1-3 (35852) – 1MVA, Arlington St 20 (31463) – 800kVA, Piccadilly Green Pk Stn (36746) - 1MVA, and Berkley Street 40-50 (36300) – 2 x 800kVA. Figure 18 – DNV Utilisation – Piccadilly Ritz Hotel Looking at the utilisation data in Figure 18 (over the past 2-3 years or to the coldest winter) from DNV for the closest secondary substation, Piccadilly Ritz Hotel Substation (31529) with a transformer rated at 1MVA. The maximum demand on Piccadilly Ritz Hotel Substation (supplying LV network mains and direct services) already exceeds an acceptable level, in 2013 the maximum demand rose above 1MVA. On interconnected networks, the typical practice is for the maximum demand substations to be UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 27 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices kept within 80% of their name plate rating to allow for hold up (which would be 800kVA in this case). As 1MVA is the largest capacity transformer UK Power Networks uses at a secondary level, it is not possible to upgrade to a higher rated transformer. Therefore it is not possible to accommodate the 240kVA new connection on to Piccadilly Ritz Hotel substation. As an alternative point of connection, it might be possible to connect via a direct service or an existing LV main from one of the surrounding substations. N.B. Connections of ~250kVA and above should typically be connected via a direct 3 phase service, as connecting to an LV main with existing load would be likely to overload the cable (even those highly rated). Connections to Berkley Street 40-50 (36300) would not be entertained since this would require a major crossing (large associated costs) and the substation lies across a primary substation boundary, supplying a customer from different primary substation/group/busbar is not permissible since it creates circulating currents. Similarly, Piccadilly Green Pk Station (36746) would not be utilised as it is customer dedicated substation and lies across a group/busbar Boundary. Two secondary substations within the same primary substation and group/busbar boundary would be Arlington Street 1-3 (35852) and Arlington St 20 (31463). Although there maybe capacity from one of these two substations to supply a direct service, this would not be the proposed point of connection as it would introduce further multiple services to the same building therefore impact on implementing safe isolation of supplies on the premises. There should be minimal (ideally one) points of isolation, other arrangements may lead to misperception and inadvertent live equipment posing a danger of electrocution. Due to the concerns stated above, it would be proposed to the customer that a dedicated substation is installed for the Piccadilly Ritz Hotel to cater for the additional 240kVA and that existing 3 phase services (currently fed from the network substation 31529) are also transferred to this new substation. This would satisfy having a single source of supply for the 3 phase services into the building (safe isolation) as well as alleviate the load on Piccadilly Ritz Hotel network substation (31529). An appropriate HV point of connection for this dedicated substation might utilise one of the nearby HV feeders, such as W5 or NW1 on the Leicester Square Main Substation. A Parasitic Load Tripping Unit (PLTU) would be installed for the customer’s dedicated substation to ensure that the customers’ dedicated load is isolated from the network in the event of a HV Phase to Earth fault. This does have an implication on lowering the customers’ security of supply in comparison to a network substation connection. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 28 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Figure 19 – HV Geoview – Piccadilly Ritz Hotel Observing the HV cables on Geoview (Figure 19) shows a variety of HV feeders in close proximity of Piccadilly Ritz Hotel. To connect to the NW1 HV feeder group would require a main road crossing (incurring a significant cost), whereas, the W5 feeder has sections on the same side of the road as the building requiring the new connection. The importance of managing fault level in the interconnected area means that some HV feeders would be discounted from providing additional large connections. It is possible that a more expensive connection involving an alternative HV feeder would be proposed in such circumstances. Further HV analysis is required to ensure that the additional dedicated substation would integrate suitably with the existing network arrangements under both normal running conditions and in compliance with ENA Engineering Recommendation P2/6 – “Security of Supply” for n-1 conditions (loss of a single circuit). 5.2 Load Growth Driven Reinforcement In the scenario that an area of network is at risk of exceeding its intended capacity then a planning solution should also be provided to reinforce that network. Incremental load growth might have arisen due to the large volume of small service connections (small single phase supplies are not passed through the LPN distribution planning process) or natural load growth from existing connections due to increased use of energy intensive appliances. This area of network is known for having a high load density and as demonstrated above the maximum demand on Piccadilly Ritz Hotel already exceeds its 1MVA capacity (over 1MVA in 2013). The transformer could be allowed to run at 120% of its capacity (1.2MVA) for short periods or time, however, this only applies to radial networks or in normal running conditions. The transformer should not be loaded above 80% (800kVA) in an interconnected network to allow for LV hold up in the event of a circuit loss (n-1 condition). The transformer cannot be upgraded as 1MVA is the highest rated transformer used on the secondary networks. Reinforcement Options: Radialise the whole network – This would mean that transformers would not be limited to the 80% rating for hold up as it is with interconnected networks and instead could run up to 120%. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 29 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Radialise this section of network (radial embedded) – This would degrade other sites within this interconnected network i.e. there will not be sufficient capacity in the area to hold up under LV and HV faults. New substation on existing feeder – This would allow network load to be transferred from the old substation (keeping only direct services) onto a new installed network substation. Connecting this to the existing feeder would raise the fault level (~46kA) above the acceptable limit and to reduce this would require splitting some network interconnection. Splitting up the ‘network clunch’ would cause issues with the surrounding network due to loss of hold up capacity. New substation on different feeder – This would allow network load to be transferred from the old substation (keeping only direct services) onto a new installed network substation. Some interconnection would be split such that the ‘network clunch’ fault level is acceptable. By connecting this new substation to the new feeder the ‘hold-up’ capacity in the area can be retained, this would involve reconfiguring the interconnection. The screenshot in Figure 20 demonstrates the network under consideration in the DINIS tool. In proposing a reinforcement solution for the area, a fault level study would be conducted using the fault study package to ensure acceptable limits of operation and effective network protection. The proposed planning solution in this case would be to install a new network substation in close proximity to the Piccadilly Ritz Hotel (31529) substation but connecting to an alternative HV feeder. The LV network cables currently fed from the LV distribution board at Piccadilly Ritz Hotel (31529) will be transferred to the new network substation, therefore shedding load from the original transformer (only left with dedicated 3 phase services). This option will better support the surrounding network whilst satisfying concerns with keeping an acceptable fault level and having adequate hold up capacity across the interconnected network area. Ideally this new substation would be built using the existing substation space in Piccadilly Ritz Hotel (31529), however, there is not sufficient space to accommodate the equipment for a double substation and therefore an independent substation would be required. Figure 20 – DINIS Network View – Piccadilly Ritz Hotel UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 30 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 5.3 Proposed FUN-LV Method 2 As part of the FUN-LV project, this site was selected for the installation of a dual terminal PED (labelled ‘Method 2’). The device will be installed as a piece of street furniture in the pavement section adjacent to Green Park Tube Station. This dual terminal PED will enable a capacity transfer of up to 240kVA between Piccadilly Ritz Hotel (31529) and adjacent interconnected networks. Power Electronics Device Figure 21 – Proposed PED Solution – Piccadilly Ritz Hotel In the configuration proposed, the device would be jointed onto the LV main that connects Piccadilly Ritz Hotel (31529) and Link Box 30145. In addition to this jointing the trial will require that the NOP is closed (via insertion of 1 set of links) so that power can be transferred between Berkley Street 40-50 (36300)/Stratton St Stratton House (31550) and Piccadilly Ritz Hotel (31529). The diagram in Figure 23 shows the proposed design for the free standing cabinet Method 2 device and the schematic shown in Figure 22 illustrates the general arrangement of the connection to an LV network. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 31 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 1000mm 800mm 1400mm 1270mm 200mm Figure 23 – Method 2 Free Standing Cabinet Figure 22 – Method 2 general arrangement UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 32 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices FUN-LV Method Comparison and Considerations Costs – In comparison with the business as usual solutions, the PED Costs (approx. £48,000) are less than both the connection driven reinforcement (customer – approx. £152,000-£182,000 PLUS land cost value, DNO – approx. £5,000) and the load growth driven reinforcement (approx. £106,000£136,000 PLUS land cost value). Longevity – Current estimates for the lifetime of the PED equipment is under 10 years, therefore it is providing a temporary solution by delaying traditional reinforcement. A typical transformer life time would be 40 years. Security/Quality of Supply – Through capacity equalisation, the network is less overloaded and therefore at less risk of faulting. The PED is designed to improve quality of supply by providing voltage support, power factor correction, harmonic content and phase imbalance improvement. Additionally, the PED would allow a customer to connect to a network substation rather than providing the connection via a dedicated substation which would require a Parasitic Load Tripping Unit (PLTU). The PLTU device disconnects HV customers and large LV three phase customers and therefore reduces security of supply. Fault Level – The dual terminal PED can constrain the fault level, whereas the business as usual solution (new substation on interconnected network) will require splitting interconnected feeders to not further increase fault level. Equipment Size – The dual terminal PED has dimensions as shown in Figure 23. PED Location – The dual terminal PED would be installed as a piece of street furniture in the pavement section adjacent to Green Park Tube Station. Planners time – The PED solution would require LV load flow studies and fault level studies to ensure that sufficient capacity is being shared and fault level studies to ensure effective network protection. However, the BAU solution planning for this interconnected area would require a large amount of time to redesign the network as it has various constraints on accommodating further capacity. The new substation may require a new feeder to be installed from the 11kV switchboard at the main substation and currently there are no available panels at Leicester Square. The PED can provide a temporary solution at this local scale allowing time to understand what areas of load are growing in order to sensibly design a wider network area reinforcement solution. Installation time – The dual terminal PED would be delivered and installed within 2-3 days, whereas the BAU solutions (new substation) would require upwards of several weeks depending on the substation construction and alternative feeder. Planning Permissions/Consent – The dual terminal PED would require permission from the council to install the device enclosed within a kiosk, whereas the business as usual solution (new substation) would require the customer/DNO to acquire the land/space to accommodate a new substation and road closures for cable overlays. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 33 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 6 LPN Method 3: Shaftesbury Ave 125 (24410) – Interconnected Network 6.1 Connection Driven Reinforcement – Planners Log To represent a connection driven reinforcement scenario a hypothetical request was received from the customer connection gateway for a further 400kVA to be provided at 125 Shaftesbury Avenue, London, WC2. Figure 24 - Google Maps View – Shaftesbury Ave 125 UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 34 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Customer Location Figure 25 – LV Geoview – Shaftesbury Ave 125 Looking at the Geoview LV network, the closest secondary substation is Shaftesbury Ave 125 (24410) with a transformer rated at 750kVA. Nearby substations include Stacey Street (24409) – 750kVA, Shaftesbury Ave 164 (24143) – 500kVA, Charing X Rd 82 (31023) – 750kVA, and Tower Street 22 (24146) – 800kVA. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 35 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Figure 26 – DNV Utilisation– Shaftesbury Ave 125 Looking at the utilisation data from DNV for Shaftesbury Ave 125 with a transformer rated at 750kVA. The maximum demand on Shaftesbury Ave 125 already exceeds an acceptable level, in 2013 the MD rose above 800kVA. This is above 80% of the name plate rating (600kVA), which would allow for hold up. Although the transformer could be upgraded to a 1MVA capacity this would not sufficiently accommodate the 400kVA new connection. As an alternative point of connection, it might be possible to connect via a direct service from a separate substation with sufficient spare capacity. However, due to the large load requirement a particular highly rated cable type would be required, this being a single core cable (either 4 core or 8 core double run). However, this cable type is not designed to be laid in ducts or underground and typically would be used for connections in the closest proximity to the substation (same building via accessible culverts). Therefore, none of the other surrounding substations (Charing X Rd, Stacey Street, Tower Street 22 and Shaftsbury Ave 164) are close enough to transfer a direct service of this size. Another option would be to install a new network substation at 125 Shaftsbury Avenue. If a customer dedicated 500kVA substation was installed this would not provide any spare capacity should the network require it in future whereas an 800kVA network substation could supply the new 400kVA connection with 240kVA for spare network capacity (640kVA at 80%). Additionally using an 800kVA transformer does not significantly alter the overall project cost or space required. In this scenario it was supposed that the customer requesting the new connection was not associated with the existing direct services attached to Shaftsbury Ave 125 and therefore these could not be transferred to plan a dedicated substation. Being a network substation, the costs would be apportioned between the DNO and the customer on a pro rata basis, in this case 50/50 (400kVA of 800kVA). An appropriate HV point of connection for this network substation might utilise one of the nearby HV feeders, such as E4 or E5 on the Fisher Street B Main Substation. If a network substation is feasible then the Parasitic Load Tripping Unit (PLTU) would not be required and therefore there is not an added detriment to the security of the customers supply. In order to support/be supported via the interconnected network, the new 800kVA network substation would require 3 LV cables to be transferred from Shaftesbury Ave 125 (24410) on to its LV distribution board. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 36 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Figure 27 – HV Geoview – Shaftesbury Ave 125 Observing the HV cables on Geoview shows that using a different HV feeder would require a HV cable to be looped from across the main road and this would likely require extensive excavation across the road (old ducting would not accommodate new HV cable). Due to the high fault level on this network an alternative feeder would be required for the HV point of connection and this would incur higher costs. Further HV analysis is required to ensure that the additional substation would integrate suitably with the existing network arrangements under both normal running conditions and in compliance with Engineering Recommendation P2/6 for n-1 conditions (loss of a single circuit). UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 37 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 6.2 Load Growth Driven reinforcement This area of network is known for having a high load density and as demonstrated above the maximum demand on Shaftesbury Ave 125 already exceeds its 750kVA capacity (over 800kVA in 2013). The transformer could be allowed to run at 120% of its capacity (900kVA) for short periods of time, however, this only applies to radial networks or in normal running conditions. The transformer should not be loaded above 80% (600kVA) in an interconnected network to allow for LV hold up in the event of a circuit loss (n-1 condition). The transformer could be upgraded by replacing the original 750kVA rated transformer to one with a 1MVA rating. Reinforcement Options: Increase transformer rating – Installing a 1MVA transformer replacement would increase the 80% rating to 800kVA, however, the maximum demand has already exceeded 800kVA in 2013. New substation on existing feeder – This would allow network load to be transferred from the Shaftesbury Ave 125 onto the new network substation. In order to coordinate with the modern ACB protection, an 800kVA transformer should be installed. New substation on different feeder – This would allow network load to be transferred from the Shaftesbury Ave 125 onto the new network substation. An alternative HV feeder would require a HV cable to be looped across the main road. This screenshot demonstrates the network under consideration in the DINIS tool. In proposing a reinforcement solution for the area, a fault level study would be conducted using the Fault Study Package (FSP) to ensure acceptable limits of operation and effective network protection. Figure 28 – DINIS Network View – Shaftesbury Ave 125 The proposed planning solution in this case would be to install a new network substation within the existing Shaftesbury Ave 125 (24410) substation space and connecting to an alternative HV feeder. Three LV network cables will be transferred onto the new substation to shed load from the original transformer and support the interconnected network. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 38 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 6.3 Proposed FUN-LV Method 3 As part of the FUN-LV project, this site was selected for the installation of a multi-terminal PED (labelled ‘Method 3’). This multi-terminal PED will enable a capacity transfer of up to 400kVA between Shaftesbury Ave 125 (24410) and adjacent interconnected networks. Figure 29 – Proposed PED Solution – Shaftesbury Ave 125 In the configuration proposed, the device would be installed within Shaftesbury Ave 125 (24410) substation and connected to the adjacent interconnected network via fuse ways on the LV distribution board. In addition, this trial will require that the NOPs at LB 222111 and LB 222116 are closed (via insertion of 1 set of links) and cross-jointing is carried out to at LB 222116 (as shown in Figure 29). This will allow power to be transferred between Stacey Street (24409)/Shaftesbury Ave 151-165 (21388), Charing X Rd 82 (31023)/Tower Street 22 (24146) and Shaftesbury Ave 125 (24410). The schematic shown in Figure 30 illustrates the general arrangement for the connection of the multiterminal device to an LV network. A photo of the device is presented in Figure 31, this shows the internal build of a single power electronics panel and control panel. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 39 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Figure 30 – Method 3 general arrangement Figure 31 – Method 3 Control Panel and Power Electronics Panel (1 of 3) UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 40 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices FUN-LV Method Comparison and Considerations Costs – In comparison with the business as usual solutions, the PED Costs (approx. £124,000) are less than the connection driven reinforcement (customer – approx. £150,000, DNO – approx. £10,000) and more than the load growth driven reinforcement (approx. £100,000). Longevity – Current estimates for the lifetime of this equipment is under 10 years, therefore it is providing a temporary solution by delaying traditional reinforcement. Security/Quality of Supply – Through capacity equalisation, the network is less overloaded and therefore at less risk of faulting. Fault Level – The multi-terminal PED can constrain the fault level, whereas the business as usual solution (new substation on interconnected network) will require splitting interconnected feeders to not further increase fault level. Equipment Size – The multi-terminal PED has dimensions 1.8H x 2.4W x 0.6D metres. The setup will include Litton connectors (disk clamps for busbar) attaching to fuse ways on the LV distribution board at one end and the PED on the other, it may also include HVAC equipment. PED Location – The multi-terminal PED would be installed within the substation Shaftesbury Ave 125 (24410). Planners time – The PED solution would require LV load flow studies and fault level studies to ensure that sufficient capacity is being shared and fault level studies to ensure effective network protection. However, the business as usual solution planning for this interconnected area would require a large amount of time to redesign the network as it has various constraints on accommodating further capacity. The new substation may require a new feeder to be installed from the 11kV switchboard at the main substation. The PED can provide a temporary solution at this local scale allowing time to understand what areas of load are growing in order to sensibly design a wider network area reinforcement solution. Installation time – The multi-terminal PED would be delivered and installed within 5-6 days (including 3 additional days for cross jointing), whereas the business as usual solution (new substation) would require upwards of several weeks depending on the substation construction and alternative feeder. Planning Permissions/Consent – The multi-terminal PED would not require planning permission as it will be installed within the existing substation, whereas the business as usual solution (new substation) would require the customer/DNO to acquire the land/space to accommodate a new substation and road closures for cable overlays. Ventilation – The multi-terminal PED may additional HVAC equipment to keep the environment within an acceptable temperature range. This will require suitable venting arrangements within the substation and additional space. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 41 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 7 Trial Site Case Studies – Brighton Sites The following trial site case studies cover specific FUN-LV trial sites being selected for the installation of PEDs in Brighton (SPN). These case studies illustrate the traditional planning considerations for accommodating PEDs at these selected sites. There are three SPN case studies in this section, these include an example for each of the three Methods in the FUN-LV project. 8 SPN Method 1: Regent Hill (523461) – Radial Network 8.1 Example FUN-LV Method 1 As part of the FUN-LV project, this site was considered for the installation of a simple PE method comprising of LV circuit breakers at both substations with no link box switches required (referred to as ‘Method 1a’). These LV circuit breakers allow automated operation and will enable a capacity transfer of up to 200kVA between 523461 Regent Hill and 523686 M&S Regents Hill. The primary benefit of this arrangement is to reduce the load on substation 523461 Regent Hill. Figure 32 shows the proposed routes of interconnection to balance the loading across the two substations. Figure 32 – Traditional Planning for PED Solution – Regent Hill Substation Current kVA Balanced kVA Increase kVA Regent Hill 400 300 -100 M&S Regent Hill 500 600 100 Table 2 – Example Load Transfers – Regent Hill UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 42 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices The example load transfers listed in Table 2 are based on the of proportional loading of the transformers i.e. 100kVA may be transferred on LV network from 523461 Regent Hill to 523686 M&S Regent Hill. Load flow studies would be required to model the power transfer for Method 1 trials. Table 3 lists the cables and ratings used in this LV network. These traditional cable ratings are based on the assumption of a cyclic load pattern. In the FUN-LV trials the transfer profiles are expected to differ from this typical load pattern, however, the user will be able to input cable ratings into the PED control algorithm ensuring that the loading does not incur an adverse impact on the cable. The PED will not make a transfer that is greater than this threshold, for greater than a certain amount of time (i.e. will allow for an acceptable overload and then limit transfer and alert control). Cable Summer Direct Rating Amps kVA 0.3 445 320 0.1 250 180 unknown ? ? Table 3 – Cable Ratings – Regent Hill This network involves one section of unknown cable construction, and one length of .1 which could potentially act as throttles to load transfer. The fuses at 523686 M&S Regent Hill act as the open point on this interconnection, 523461 Regent Hill has an approximate 61kVA load on this feeder, this would form part of the 100kVA potential required loading on this interconnection. For business as usual, the .1 cable, dark blue, is of suitable capacity, with an 80kVA potential for additional load transfer. The unknown cable, light blue, forming the first section out of 523686 M&S Regent Hill, is believed to be .3 construction meaning this is also of suitable capacity. This would need to be positively confirmed on site rather than assumed. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 43 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 9 SPN Method 2: Duke Street (523338) – Radial Network 9.1 Example FUN-LV Method 2 As part of the FUN-LV project, this site was considered for the installation of a dual terminal PED (labelled ‘Method 2’). The device will be installed as a piece of street furniture in the pavement section adjacent to link box 4K1565. This dual terminal PED will enable a capacity transfer of up to 240kVA between 523338 Duke Street and 523653 Churchill Square East. The primary benefit of this arrangement is to reduce the load on substation 523338 Duke Street. Figure 33 shows the proposed routes of interconnection to balance the loading across the two substations. Substation Current kVA Balanced kVA Increase kVA Duke Street 505 293 -212 Churchill Square East 375 587 212 Table 4 –Example Load Transfers – Duke Street It is possible to balance loading as desired, the example listed in Table 4 demonstrates transfers based on proportional loading of transformers i.e. 212kVA may be transferred on LV network from UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 44 of 49 Figure 33 – Traditional Planning for PED Solution – Duke Street Guidance Document Traditional Planning Considerations for Power Electronics Devices 523338 Duke Street to 523653 Churchill Square East. The dual terminal PED used in the Method 2 trials can transfer up to 240kVA. Table 5 lists the cables and ratings used in this LV network. These traditional cable ratings are based on the assumption of a cyclic load pattern. In the FUN-LV trials the transfer profiles are expected to differ from this typical load pattern, however, the user will be able to input cable ratings into the PED control algorithm ensuring that the loading does not incur an adverse impact on the cable. The PED will not make a transfer that is greater than this threshold, for greater than a certain amount of time (i.e. will allow for an acceptable overload and then limit transfer and alert control). Cable Summer Direct Rating Amps kVA 300H 468 337 .3 445 320 .15 290 209 .1 250 180 unknown ? ? Table 5 – Cable Ratings – Duke Street This network involves two sections of adjoining unknown cable construction, one length of .15 cable construction and one length .1 which could potentially act as throttles to load transfer. Two link boxes exist on the cable route identified via Boyces’ Street, 4K1565 and 4K1564. Both of these have the links removed such that the cable section between them is currently fed from a third substation 523751 77 West Street, this section of cable is also loaded feeding all the customers located along Boyce’s Street. Combined with this section being comprised of the unknown and .1 cable sections it is taken that a new cable would need to be laid along Boyce’s Street, with an additional link box to be able to enable the required load transfer network arrangement. Existing open points would remain where they are. Power electronics would be installed across the new link box. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 45 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Figure 34 – New Cable Installation Boyces’ Street The .15 cable between 523338 Duke Street and link box 4K1565 has a quoted capacity just under the required load transfer for business as usual. This indicates that the cable may become stressed and subject to failure if the maximum load transfer is sustained for any length of time. This would need to be monitored carefully, more detailed load profiling completed or pro-actively overlaid to eliminate the possibility. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 46 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices 10 SPN Method 3: New Road (523230) – Radial Network 10.1 Example FUN-LV Method 3 As part of the FUN-LV project, this site was considered for the installation of multi-terminal PED (labelled ‘Method 3’). This multi-terminal PED will enable a capacity transfer of up to 400kVA between 523637 Prudential North Street and adjacent networks (522941 Vokins and 523230 New Road). The primary benefit of this arrangement is to reduce the load on substation 523230 New Road. Figure 32 shows the proposed routes of interconnection to balance the loading across the three substations. Figure 35 – Traditional Planning for PED Solution – New Road Substation Current kVA Balanced kVA Increase kVA Vokins 275 529 254 Prudential 725 661 -64 New Road 850 661 -189 Table 6 – Example Load Transfers – New Road It is possible to balance loading as desired, the example listed in Table 4 demonstrates transfers based on proportional loading of transformers i.e. 189kVA may be transferred on LV network from 523230 New Road to 523637 Prudential North Street, and 254kVA must be transferred on LV network from 523637 Prudential North Street to 522941 Vokins. The multi-terminal PED used in the Method 3 trials can transfer up to 400kVA. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 47 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices Table 7 lists the cables and ratings used in this LV network. These traditional cable ratings are based on the assumption of a cyclic load pattern. In the FUN-LV trials the transfer profiles are expected to differ from this typical load pattern, however, the user will be able to input cable ratings into the PED control algorithm ensuring that the loading does not incur an adverse impact on the cable. The PED will not make a transfer that is greater than this threshold, for greater than a certain amount of time (i.e. will allow for an acceptable overload and then limit transfer and alert control). Cable Summer Direct Rating Amps kVA .3a 351 253 .3 445 320 300H 468 337 unknown ? ? Table 7 – Cable Ratings – New Road This network involves three sections of unknown cable construction, and one length .3a which potentially acts as a throttle to load transfer. 523230 New Road 523637 Prudential North Street The fuses at 523230 New Road act as the open point on this interconnection, 523637 Prudential North Street has an approximate 100kVA load on this feeder, meaning a potential required loading of 289kVA on this interconnection. This would require the two unknown cable sections, light blue on the plan, to be investigated to determine if an upgrade to 300H is required. A more in depth analysis of the .3a cable, dark blue on the plan, would be required to determine the necessity for it to be upgraded to 300H construction. This replacement is dependent on the distribution of existing load on this cable. Using existing planning tools it is difficult to determine given the clarity of MPAN information available. 523637 Prudential North Street 522941 Vokins The fuses at 523637 Prudential North Street act as the open point on this interconnection, 522941 Vokins has a currently unknown loading on this interconnection. It is known that there is a load of 102kVA – 150kVA located at unit 5 of 32-36 North Street, however it is unknown if this is serviced via the 300H or six single core 600a cables at 522941 Vokins. Either way the suggested implication is that approximately half the existing load on the substation must be on the 300H cable, if not more. This means that even ignoring the unknown cable section, light blue on plan which would require investigating, the 300H cable forming the first section of this feeder would be overloaded in balancing the existing load on these three feeders, requiring a capacity in the order of 390kVA (136kVA half load + 254kVA transfer), this is more than 50kVA over the rating of the cable. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 48 of 49 Guidance Document Traditional Planning Considerations for Power Electronics Devices In order to be able to accept the transfer required to balance the existing loading of these three substations, one of the following would need to be implemented: 1) Transferring off the existing feeder load onto another adjacent LV feeder, this would require moving it to another substation which may potentially have other knock on effects. 2) The establishing of an additional interconnection between these substations, availability of spare ways at the substations/ducting/cable trays unknown at this time. UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP Page 49 of 49