D1.1 Definition of use cases

This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 SCARLET Superconducting CAbles foR sustainabLe Energy Transition 1.09.2022 – 28.02.2027 Call identifier: HORIZON-CL5-2021-D3-02 D1.1: Definition of use cases Lead partner: NEXANS Fr Authors: Arnaud ALLAIS, Nexans Fr Christian-Eric BRUZEK, ASG Christophe CREUSOT, SGI Beate WEST, Nexans De Marte GAMMELSAETER, SINTEF Finbarr COGHLAN, SuperNode Submission date: 16/12/2022 Dissemination level PU Public SEN Sensitive, limited under the conditions of the Grant Agreement X This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 Document history Issue date Version Changes made / Reason for this issue 06/12/2022 00 Initial version 15/12/2022 01 After partners review This document only reflects the author’s view. The programme authorities are not responsible for any use that may be made of the information contained therein. D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 3 3 INDEX INDEX 3 EXECUTIVE SUMMARY 6 1 INTRODUCTION 7 2 TYPE AND CHARACTERISTICS OF MVDC POWER LINKS 8 3 CABLE SYSTEMS LENGTHS 9 3.1 LIMITATIONS COMING FROM PRODUCTION 9 3.2 LIMITATIONS COMING FROM TRANSPORT 9 3.3 LIMITATIONS COMING FROM INSTALLATION 10 3.4 LIMITATION COMING FROM DESIGN AND EXPLOITATION 11 3.5 CONCLUSION ON LENGTH LIMITATION 11 4 COOLING SYSTEMS 12 5 CABLE SYSTEM LAYOUT 14 6 CONVERTER ARCHITECTURES 14 7 CABLE SYSTEM STRUCTURE 16 7.1 NUMBER OF SUPERCONDUCTING POLES PER CABLE 16 7.2 NUMBER OF CABLES PER LINK 18 8 LIST OF POTENTIAL USES CASES 20 9 CRITERIA AND SELECTION OF USE CASES FOR THE PROJECT 21 9.1 CRITERIA 21 9.2 ANALYSIS 22 D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 4 4 10 CONCLUSION 23 11 BIBLIOGRAPHY 24 D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 5 5 Glossary DC = Direct Current GW = GigaWatt HTS = High Temperature Superconductors (superconductor materials with critical temperature above 30 K) K = Kelvin kA = KiloAmps kV = kiloVolt kVDC = kiloVolt Direct Current LH2 = Liquid Hydrogen (around 20 K) LN2 = Liquid Nitrogen (range of 67 to 80 K) LNG = Liquid Natural Gas (mainly liquid methane) MgB2 = Magnesium Diboride MVDC = Medium Voltage Direct Current PCCO = Point of Common Coupling Offshore (Junction between inter-array network and export network) PCCT = Land power substation (to connect the wind park to the transmission grid through the export cable) ReBCO = Rare earth Barium Copper Oxide (family of ceramics exhibiting superconductivity up to 90K). Rare earth = Yttrium (Y), gadolinium (Gd)… SCTL = Superconducting transmission line Tc = Critical temperature of superconductors Top = Operational temperature (liquid nitrogen around 70 K for HTS and liquid hydrogen around 20 K for MgB2) D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 6 6 EXECUTIVE SUMMARY This deliverable aims at identifying the relevant use cases for HTS and MgB2 superconducting cable systems up to 100 kVDC with powers of the order of 1 GW using the different technologies available. Based on the main characteristics of onshore and offshore power links for renewable farm-to-grid or grid-to-grid connection, of cooling systems, and the constraints in terms of unit lengths for superconducting cable systems, a reduced set of cable layouts is proposed to address all types of power links. The selected cable layouts, two for onshore and one for offshore, are defined by a unit length of cable (core and cryostat) linked to the distance between the cooling stations for a given range of cooling power at operational temperatures (close to 70 K for HTS and 20 K for MgB2). Each cable layout requires specific types of accessories and ancillary services. The converter architecture depends strongly on the power level (1 or 2 GW) in the existing configuration. For each power level, two possible cable system structures for HTS and two for MgB2 have been selected, with different properties in term of rated voltage, environmental impact, redundancies, expected cost and cable productions runs. Depending on the performance criteria that are requested by customers, a selection is proposed with the most appropriate use cases to be studied in depth in terms of technical and economical assessments, as well as environmental impacts. D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 7 7 1 INTRODUCTION In the call text, it was stated that the voltage and power levels as well as lengths below should be considered: - Up to ±100 kVDC, up to 1 GW power, superconducting cable system (HTS) up to 5 km, onshore. - Up to ±100 kVDC, up to 1 GW power, superconducting cable system (HTS) up to 100 km, offshore. - A superconducting transmission line (SCTL) based on MgB2 LH2 cooled, for DC with a length up to 1 km and above, onshore. The voltage level and the cable section should be designed to have the maximum benefits in terms of insulation requirements and conductor section for a capacity transfer of 10 kA and above. For the project we have selected an operating voltage of 25 kVDC. In this report, the scope of work has been extended to relevant levels of parameter values to address present and future markets for power links using HTS and MgB2 superconducting cable systems and associated technologies. For each technology, from cooling and superconducting cable to conversion, the key characteristics having an influence on the superconducting cable system will be highlighted to drive the choices of cable layouts in a first phase (chapter 2, 3, 4 and 5) and cable system structures in a second phase (chapter 6, 7 and 8). A more in-depth status will be proposed for the different technologies in the works carried out withinWP2 (HTS long cable design & manufacturing), WP3 (Offshore architectures), WP4 (MgB2 cable design & engineering) and WP5 (System protection). A set of criteria is proposed to drive the final selection depending on customer needs (chapter 9). D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 8 8 2 TYPE AND CHARACTERISTICS OF MVDC POWER LINKS The project SCARLET aims at enabling a larger integration of renewable energy at different scales using superconducting cable systems at DC medium voltage. Such cable systems can cost effectively connect the renewable generation site to the nearest grid: - for offshore thanks to lower platform size (no transformer) and reduced footprint on the coast - for onshore thanks to high ampacity without thermal impact. Figure 1: Distance to shore and water depth of current and future offshore wind projects [1] At larger grid scale to manage intermittency of an energy mix based on renewable, the grids of different countries should be interconnected and able to transmit a large amount of power. Finally, large end users inside the cities, industrial areas with intensive electricity needs or crossing of protected areas or natural obstacles can find a solution in MVDC power links based on superconductors. Table 1: Type and Characteristics of MVDC power links Type of link Description Characteristics Onshore Offshore R2G = Renewable to Grid Wind Solar 1 to 20 km 10 to 250 km D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 9 9 G2G = Grid to Grid interconnection Between countries Grids reinforcement or stabilization (FACTS) 1 to 20 km 10 to 250 km Congested areas (cities, industry intensive...) Protected areas Natural obstacles Seabed mounted or floating 3 CABLE SYSTEMS LENGTHS 3.1 Limitations coming from production Depending on the type of market, cable plants can be equipped with drum pay off and take up (onshore) or turn tables (offshore). Typical drum capacity can vary from 500 m to 2 km depending on cable outer diameter (cryogenic envelope) and linear weight. This value will be represented by the acronym LoD standing for “Length on a Drum” in the rest of the document. For plants producing offshore cables, turn tables are mandatory and can reach up to 10 000 tons. Usually, the turn table in the factory has a capacity in the same range as the turn table on the installation ship. 3.2 Limitations coming from transport • For onshore projects o Two types of transport are possible, by road or along river or channel. o Drums are suitable for all type of transports. Small turn tables on trucks or barge can be considered if the project is easily accessible and close to the sea, a river or a channel. D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 16 16 7 CABLE SYSTEM STRUCTURE 7.1 Number of superconducting poles per cable The superconducting cable comprises a MV cable core inside a flexible cryostat. Depending on the converter architecture described in chapter 6, three types of cable cores can be used to transmit DC power: - 1 pole (symmetric monopole architecture for converter): o to transmit rated current at rated voltage o one dielectric sized for rated voltage Figure 10. HTS cables with 1 pole each - 2 asymmetric poles (bipolar architecture for converter): o 1st pole to transmit rated current at rated voltage o one dielectric sized for rated voltage o 2nd pole for the return of the rated current at 0 volt (neutral conductor) Figure 11. HTS cable with 2 asymmetric poles (+ /0 or - /0) - 2 symmetric poles (symmetric monopole architecture for converter): o 1st pole to transmit rated current at rated voltage o 1st dielectric sized for 2 times the rated voltage o 2nd pole for the return of the rated current at opposite voltage compared to the 1st pole o 2nd dielectric sized for the rated voltage D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 17 17 - - Figure 12. HTS cable with 2 symmetric poles beneath a copper screen (neutral) (+ / - /0 ) Pros and cons of the three types are listed in Table 5. Table 5: Benefits and drawbacks of the 3 types of DC HTS cable cores Type of DC superconducting cable core Benefits Drawback 1 pole • Compact • Uses less than half of superconductors compared to the 2 other types • Magnetic field outside the cable • Requires 2 cables to transmit full power • No redundancy or degraded mode to transmit part of the energy 2 asymmetric poles • No magnetic field outside the cable • Still possible to transmit 50% of the power if one cable fails • Requires twice the amount of superconductors compared to the 1 pole type • Requires 2 cables to transmit full power 2 symmetric poles • No magnetic field outside the cable • Requires only 1 cable (less cable cryostat length) • Requires twice the amount of superconductors compared to the 1 pole type • No redundancy or degraded mode to transmit part of the energy • Larger core diameter and production cost due to the 2 dielectric layers • Requires a return line for cooling fluid For each type, the layers composition is detailed in Table 6. Table 6: Composition of DC HTS cable cores Composition 1 pole 2 asymmetric poles 2 symmetric poles Former A stranded copper conductor or a tube (corrugated tube for example) SuperPole 1 One or several superconducting layers made of tapes/wires wound on a cylindric support Dielectric 1 Lapped dielectric made of insulation material that will be impregnated by a cooling fluid during cool down D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 18 18 SuperPole 2 None One or several superconducting layers made of tapes/wires wound on a cylindric support Dielectric 2 None None Lapped dielectric made of insulation material that will be impregnated by a cooling fluid during cool down Screen One or several layers made of stranded copper tapes 7.2 Number of cables per link Depending on the converter architecture and the type of DC cable core, the link should comprise a certain number of cables. For powers up to 1 GW, the symmetric monopole architecture is preferred (see chapter 6). Two options are possible: • Two cables with 1 pole type 50 kVDC 10 KA HTS/25 kVDC 20 kA MgB2 cables Figure 13: A 1 GW power link based on two HTS DC cables with 1 pole (cable 1: 10 kA@+50kV and cable 2: -10 kA@-50kV) • One cable with 2 symmetric poles type 50 kVDC 10 kA HTS/25 kVDC 20 kA MgB2 cable Figure 14. A 1 GW power link comprising one HTS cable with 2 symmetric poles. Here a cooling fluid return line is needed but not represented. Pole 1 = 10 kA@+50 kV and Pole 2 = -10 kA@-50 kV) D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 19 19 For powers of 2 GW, two types of power links are possible, and the preferred architectures are bipolar or with 2 independent asymmetric poles (see chapter 6): • Two HTS cables with 1 pole type at 100 kVDC 10 kA/50 kVDC 20 kA MgB2, by connecting the two converters to the same middle point but not to the cable screen Figure 15. A 2 GW Power link based on two 1 pole HTS DC cables (Cable 1: 10 kA@+100 kV and cable 2: -10 kA@-100 kV) • Two HTS cables with 2 asymmetric poles type 100 kVDC 10 kA HTS/50 kVDC 20 kA MgB2, by connecting 0 poles of independent asymmetric converters together on both cable sides through the cable screen. Figure 16. A 2 GW Power link based on 2 asymmetric poles HTS DC cables (Cable 1: 10 kA@+100 kV / -10 kA@0 V and cable 2: -10 kA@-100 kV / +10 kA@0 V) D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 20 20 8 LIST OF POTENTIAL USES CASES From the information presented in chapters 6 and 7, two power levels can be addressed with cable structure with or without a second pole. The study of the different configurations of power links up to 100 kVDC leads to 8 different structures (4 HTS and 4 MgB2) of superconducting cables carrying powers of 1 and 2 GW (see Table 7). Table 7: List of superconducting cable system structures for power link carrying 1 and 2 GW Ref Cable(s) structure (diel = dielectric) Number of superpoles Minimum number of cables per link SuperPole 1 Voltage [kVDC] SuperPole 2 Voltage [kVDC] Current [kADC] Archit. Convert. Transmitted Power [GW] 70K_ 1 Former / HTS 10kA / diel 50 kV / Copper 1 2 + 50 and - 50 NA 10 Monopol Sym 1 70K_ 2 Former / HTS 10kA / diel 100kV / HTS 10kA / diel 50kV / Copper 2 1 50 -50 10 Monopol Sym 1 70K_ 3 Former / HTS 10kA / diel 100 kV / Copper 1 2 100 NA 10 Bipolar (0/100) 2 70K_ 4 Former / HTS 10kA / diel 100 kV / HTS 10kA / Copper 1 2 100 0 10 2 ind Asym Monopol (0/100) 2 20K_ 1 Copper / MgB2 20kA /diel 25 kV / Copper 1 2 + 25 and - 25 NA 20 Monopol sym 1 20K_ 2 Copper / MgB2 20kA / diel 50 kV / MgB2 20kA / diel 25 kV / Copper 2 1 25 -25 20 Monopol sym 1 20K_ 3 Copper / MgB2 20kA /diel 50 kV /Copper 1 2 50 NA 20 Bipolar 2 20K_ 4 Copper / MgB2 20kA /diel 50 kV / MgB2 20 kA /Copper 1 2 50 0 20 2 ind Asym Monopol 2 Note that the cable structures corresponding to HTS 10 kA@50 kV with HTS screen and to MgB2 20 kA@25 kV with MgB2 screen have not been selected as it is not possible to inject currents in the D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 21 21 superconducting screens at 1 GW with a monopole symmetric converter. The 8 cable structures can be practically used in the 3 cable system layouts of Table 4: Superconducting cable systems layouts. 9 CRITERIA AND SELECTION OF USE CASES FOR THE PROJECT 9.1 Criteria We have 24 potential use cases after a first selection based on - a reduced number of elementary cable layout (2 onshore and 1 offshore, see Table 4) that allows us to treat all types of links - the adequate combination of converter architectures and cable system structures (see Table 7) The following criteria are proposed to differentiate the different cable system structures: - level of power reachable - rated voltage - presence of electromagnetic fields (EMF) near the cable - existence of redundancy or degraded mode - number of cables needed - return line - quantity of superconductor - cable production runs (runs through the stranding or lapping lines) For HTS we got the following table: Table 8: Differentiation matrix for HTS cable structure Ref Power Rated voltage EMF Redund. Nb cable Return line Qty HTS Cable runs 70K_1 1 50 kV yes 0 2 0 m - 70K_2 1 50 kV no 0 1 1 m +++ 70K_3 2 100 kV yes 0 2 0 m + 70K_4 2 100 kV no 50% 2 0 2 x m ++ For MgB2 we got the following table: Table 9: Differentiation matrix for MgB2 cable structure Ref Power Rated voltage EMF Redund. Nb cable Return line Qty MgB2 Cable runs 20K_1 1 25 kV yes 0 2 0 m - 20K_2 1 25 kV no 0 1 1 m +++ 20K_3 2 50 kV yes 0 2 0 m + 20K_4 2 50 kV no 50% 2 0 2 x m ++ D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 22 22 9.2 Analysis The increase in power requires an increase in voltage based on the rules for building converters. The only cases that offer partial redundancies are the cases K_4 that allow to keep 1 GW out of 2 GW in case of loss of one of the cables. The lowest consumption of superconducting tape per GW transmitted are the cases K_3, especially interesting for HTS. The cases K_1 and K_2 are very similar in terms of power rating and only a more detailed study could tell which one has the lower thermal losses and pressure drop. The only major difference is that K_2 has a coaxial configuration that allows for the suppression of any electromagnetic field. The price to pay is a more complex cable manufacturing process, resulting in higher lead times due to an increased number of runs through the machines. Depending on customer priority regarding the power level, redundancy, cost, or presence of electromagnetic fields, the following cable system options are available. Table 10: Choice of superconducting cable structure cases considering power, redundancy, EMF, expected cost and lead time Power Redundancy EMF Cost Cabling runs Preferred case 1 GW 0 - - +++ 70K_2 and 20K_2 1 GW 0 + - - 70K_1 and 20K_1 2 GW 50% - ++ ++ 70K_4 and 20K_4 2 GW 0 + + + 70K_3 2 GW 50% - ++ +++ 2 x K_2 2 GW 50% + ++ - 2 x K_1 D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 23 23 10 CONCLUSION This report is a synthesis of all technologies associated to MVDC superconducting cable systems with the target to guide the selection of relevant uses cases for the different types of links: renewables-togrid connections links: renewable connection as well as grid-to-grid connections. Similar structures and layouts of cable systems can be used for both types of links, and to address the specific needs in term of overall length and environment. Two key values have been introduced: • LoD = maximum length than can be loaded on a drum (weight or volume constraints) • Max THL = maximum thermohydraulic length that can be cooled with a cooling station at one end. The Max THL will be evaluated for each combination of cable core, cable cryostat with or without return line selected for the use cases in WP2, WP3 and WP4. Two onshore layouts have been proposed: one with distributed small cooling units at every joint bay with very optimized cable cryostat and cable core, and one with a cooling station every maximum unit length possible (Max THL). For offshore systems, the cable layout consists of a repetition of modules of Max THL unit lengths cooled independently from an intermediate platform. The cable structures are mainly driven by the converter architecture that imposes the voltage for a given power range r and the possibility to have return current in a second pole in the cable. The final choice of an adequate cable system structure is very dependent on the customer requirements. If the presence of magnetic fields outside the cable is a constraint, the K2 and K4 cases are possible with cable structures having 2 poles respectively at 1and 2 GW. If redundancy is required, the full power should be 2 GW, either with a bipolar converter architecture of 2 GW and the K_4 structure with 2 poles cable structure, or with 2 x 1 GW symmetric monopole converters and 4 x 1 pole cables (K_1) or coaxial 2 x 2 poles (K_2). At this stage it is very difficult to predict the acceptable level of magnetic field, the power level as well as the need for redundancy, therefore further evaluations need to be done in the relevant WPs. Furthermore, the advisory group should be consulted to eventually reduce the number of cable structures to be studied in depth. D1.1: Definition of use cases This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101075602 24 24 11 BIBLIOGRAPHY [1] Y. F. Bi, “Cooling and Cryocoolers for HTS Power Applications,” Applied Superconductivity and Electromagnetics, vol. 4, no. 1, pp. 97-108, 2013. [2] P. Higgins and . A. Foley, “The evolution of offshore wind power in the united kingdom,” Renewable and Sustainable Energy Reviews, vol. 37, no. Ocotber 2015, pp. 599-612, 2014.