DEMO 5: HVDC Superconducting Link

Transcription

1 DEMO 5: HVDC Superconducting Link INNOVATIVE NETWORK TECHNOLOGIES AND THE FUTURE OF EUROPE'S ELECTRICITY GRID BEST PATHS DISSEMINATION WORKSHOP MADRID, 22 of November 2017 Christian-Eric BRUZEK (Nexans France)on behalf of Demo 5 team

2 Bulk power: is there an alternative solution to UHVDC? 1100 kv HVDC transformer for the 3284 km (OHL, 12 GW) Xinjiang-Anhui link Picture published with Siemens press release, 07/11/2017 2

3 What is superconductivity? Superconductors = almost perfect conductors of electricity: no electrical resistance! R (W) Superconducting domain Temperature Normal metal T c R > 0 R 0 T = 0 K -273 C Absolute zero Superconducting state T c Critical temperature Superconductor T (K) B c Magnetic field J c Current density Superconducting materials have a huge current rating: at least 150 times greater than copper Superconducting cables provide a new way to solve power transmission (voltage x current) issues by increasing the current (up to 5 ka AC or beyond 20 ka DC) rather than the voltage 3

4 Requirement of cooling at very low temperatures T = 0 C 273 K (water becomes ice) Ambient temperature T = 200 K -73 C Temperature (K) Superconducting materials Cryogenic fluids Industrial cooling HTS cuprates -200 C Liquid nitrogen MgB 2 Extreme cold T = 0 K -273 C Absolute Zero (lowest temperature that can be reached in the universe) -250 C Timeline of discovery Liquid hydrogen (or helium K / 20 bar) Liquid helium 4

5 How to transmit bulk power 3-5 GW? (examples of corridors) Overhead lines Gas insulated lines XLPE cables Nelson River DC line (Canada) MVA (+2000 under construction) 15.5 m Geneva, Palexpo Link 2001, 470 m, 220 kv / 2 x 760 MW Frankfurt Airport, Kelsterbach Link 2012, 900 m, 400 kv / 2 x 2255 MW Raesfeld (380 kv AC, Germany) 2x 1800 MW 34 m 47 m 8 m Clearing width 45 m Right-Of-Way width 66 m 5

6 Objectives of our demonstration 1. Demonstrate full-scale 3 GW class HVDC superconducting cable system operating at 320 kv and 10 ka 2. Validate the novel MgB 2 superconductor for high-power electricity transfer 3. Provide guidance on technical aspects, economic viability, and environmental impact of this innovative technology 6

7 Demonstrator technical specification and testing strategy Characteristics Structure Power Voltage Current Monopole 3,2 GW 320 kv 10 ka Length Cooling media 20 m Liq N 2 for the electrical insulation He gas for MgB 2 conductor Losses of the demonstrator < 50 W He gas ( 20 K) Fault current AC Ripples on 10 ka DC current Change of power flow direction 35 ka during 100 ms < 1% amplitude 50 Hz 100 MW/s up to 10 GW/s Test of operating conditions on the demonstrator But use only modeling to check the cable behavior during faults and polarity changes 7

8 10 project partners for an outstanding consortium Demo coordination Optimisation of MgB 2 wires and conductors Cable system Cryogenic machines Testing in He gas Integration into the grid Cryogenic machines and cooling systems Cable system (HV dielectric behaviour) Optimisation of MgB 2 wires and conductors Cable system Testing in He gas Integration to the grid Reliability and maintenance MgB2 wires manufacturing Optimisation of wires and conductors Scientific coordination Dissemination and exploitation Cable system (terminations) Integration into the grid Socio-economical impact Reliability Losses assessment Cable system (terminations) 8

9 Completed R&D work on the MgB 2 round wires MgB 2 wires ❶ ❷ ❸ ❹ Diameter (mm) Materials Monel, Ni Monel, Ni, Nb Monel, Ni Monel, Ni, Nb MgB 2 volume fraction 17 % 12 % 30 % 12 % I c 20 K & 1 T > 650 > 650 I c 4.2 K & 3 T > r c (mm) Wire diameter homogeneity achieved along the entire batch length of about 2 km Confirmation of the wire process capability to stay within the specification limits Details presented in September at EUCAS

10 MgB 2 cable conductor designs with a fault tolerant configuration Two cable conductors considered Base design with wire #1 18 MgB 2 wires I c = A I op /I c = 0,72 D= 9,6 mm Upgraded design with the new wire #4 12 MgB Cu wires I c = A I op /I c = 0,73 D= 8,6 mm Performances For cable conductor #1: No degradation on extracted wires measured by Columbus Spa Validation by electrical characterization prototypes at CERN on 2 meter long prototype cable tested in liquid He (at 4,3 K) For cable#2: Tests are ongoing Cu MgB 2 Cu MgB 2 Modeling: transient phenomena 1- Power inversion from 100 MW/s up to 10 GW/s Limited 5 GW/s for cable conductor #1 Possible at 10 GW/s for cable conductor #2 Both cables manufactured by Nexans on industrial cabling machines 2- Fault current: 35 ka during 100 ms Both design validated 3- Converter ripple losses Negligible for both cable conductors (< 0,02 W/m) Details presented in September at EUCAS

11 Cable system demonstrator 1. Find the best the high voltage insulation of the cable and the termination to pass the type test testing sequence defined in the Cigré recommendation TB-496 Testing DC extruded cable systems for power transmission up to 500 kv when relevant 2. Verify that no charge carrier is trapped into the cable insulation that can generate disastrous voltage breakdown in operation 3. Design accessories (Termination) 4. Specify a cooling system for the demonstrator 11

12 Cable system: HV cable insulation HV cable insulation= lapped tapes impregnated with liquid nitrogen Select the best material to limit the space charges in DC with the highest voltage breakdown A versatile and quick lapping line has been designed for preparation of short model 1 samples Different tapes material (paper, PP, PPLP, etc ) Different dimensions (thickness, width, ) Different pitches and gaps between the tapes A unique cryogenic HV testing equipment for space charge measurements close to operating conditions of the cable HV insulation was designed and is operational Based on pressure wave propagation methods 12

13 Cable system: HV cable insulation Details presented in September at ISEIM 2017 Best Paths Dissemination Workshop - Demo 5 20 tests are applying 40 kv and 60 kv across a 2 mm thick Kraft paper and PPLP impregnated with Liq N 2 at 1 bar and 5 bar have been carried out Outer electrode 40 kv (20kV/mm) Short circuit Paper insulation No trapped charge carrier is found in the insulation Limited trapped charges due to the carbon black paper electrodes are found at the interfaces Inner electrode HV insulation made using paper impregnated with Liq N 2 looks like a good candidate for HVDC superconducting cable 13

14 Cable system: Full scale HV cable Testing vessel Cable Sample LN2 inlet LN2 outlet 14

15 Cable system: Full scale HV cable Measurements of performances DC Test Voltage: 298 kv Alternating tests AC/DC Increase of the test voltages in steps Impulse Voltage Test at the End Maximum test voltage* Maximum electric field AC 140 kv kv/mm DC 298 kv ** kv/mm Impulse voltage 325 kv kv/mm * without breakdown ** based on160 kv nominal voltage level 15

16 Cable system: Demonstrator design Cable cross section For 320 kv DC class cable testing up to 592 kv DC Based on electric field breakdown: 37 kv/mm * The two diameters indicate the corrugation depth 16

17 Cable system: Demonstrator design HVDC termination concept design Electrical connection to grid Helium gas inlet / outlet Hybrid current lead Termination thermal insulation Inner cryogenic insulator ~8 m height Electric field management component Termination cryostat 2,5 x 2,5 m footprint Liquid nitrogen inlet/outlet 17

18 Cooling system for the demonstration Pressurized subcooled 65 K Liq N2 is ready Available on the cable manufacturer Test HV platform Cooling system for Gas He 15K-25K Specification: K (20 bara) net cooling power with 1 m³/h He flow rate 2 Gifford-Mac Mahon cooling heads Possibility to add one Commissioning of the 20 K cooling machine is done 18

19 Grid integration / Social & economic profitability Very long cable system ehighway2050 results (several 100 km) Our Best Paths objective 19

20 Grid integration / Social & economic profitability What are the critical parameters for TSO to manage long-length systems? 1. Intrinsic features and design Management of a non-resistive component inserted into the transmission grid No dependence on scarce resources (e.g. no rare earths, limited volume of gaseous He) Simplicity of design and execution for the joints (electrical and cryogenic continuity), in order to replicate elementary sections of cable Distance between pumping and cooling stations ideally fitting with existing power substations (in average every 50 km) Ability to face ascending elevation (e.g. liquid N 2 ) 2. Installation Delivery of long lengths of cable on drums Ability to use existing techniques for civil works and installation 3. Reliability Robustness of the system, especially the joints (wire continuity, absence of insulation stress) Maintainability, availability and reliability, as key performances for industrial equipment (no outage longer than 2 minutes/year) 4. Public acceptance Installation of the underground system along a reasonable and efficient cable route 20

21 Long length cable concept First results of the cryostat modeling Two cooling fluids considered: Gas He and Liq H 2 + Integration of a Liq N 2 thermal shield [K] T in CF 15 T in,ln2 65 [K] T out CF 25 T out,ln2 80 Details presented in September at IWC-HTS Based on analytical approach: 1- Optimized friction factor f [-] = 0,04 (adapted corrugation) 2-Flat installation - no ascending elevation 3- Viscosity of Gas He is higher than Liq H 2 4- Density and Cp of Gas He is lower than Liq H 2 [MPa] P in CF 2 p in,ln2 2 [MPa] P out LH2/GHe 0,35/0,5 p out,ln2 0,2 Options G He Demo based design G He Long length Liq H2 Long length D i&o,ln2, O [mm] 129/ / /300 D i&o,ln2 I [mm] 98/ / /251 Corrugated sleeves s e t D HVI [mm] D i&o,cf, O [mm] 33/37 108/114 91/96 D i di L dc do D o D i&o,cf, I [mm] 21/23 93/99 76/81 L tot [km] Vacuum chambers 21

22 Expected results and impact Increased power at a reduced voltage level Reduced power transmission losses Transmitted power (MW) 5000 Best Paths Demo Voltage (kv) Eco-friendly Innovations in Electricity Transmission and Distribution Networks, Woodhead Publishing Series in Energy: Number 72; 2015 Edited by Jean-Luc Bessede P158 22

23 Consequent reduction of raw materials Superconducting wires MgB mm 56 mm Copper 2000 mm² Conductor A (One coin) > A Demo 5 conductor XLPE extruded cable 23

24 Reduced space for cable installation and substations Significant reduction of right-of-way corridors and of excavation work No thermal dependence to the environment Example: 6.4 GW DC power link with XLPE cables Foot print = 7 m Foot print = 0.8 m Favourable scenario: 15 C, soil 1 K.m/W 1,30 m 2,00 m 0 Resistive cables ( 8 x 400 kv - 2 ka) Our Best Paths Demo 5 (2 x 320 kv - 10 ka) 24

25 Life Cycle Assessment: Manufacturing results and uses Preliminary comparison with copper cables - 1 MgB 2 superconducting system (10kA) including the cooling system efficiency Best Paths Dissemination Workshop - Demo 5 Details presented in March at ED2E - Copper system =8 x 1250 mm 2 transferring (1A/mm 2 ) 1 x 20% 8 x 25

26 Conclusions 1. MgB 2 wire has been specially adapted to the project specifications (reduced AC losses, higher critical current density) 2. With them, two possible cable conductors have been manufactured and their characterization is ongoing. 3. Accessories (terminations and cooling systems) have been designed and specified and partially commissioned 4. So far, no technical blocking point is identified, the project is now ready for the demonstrator phase on testing platform 5. First design of cable systems have been proposed for long links 6. Based on the results and expected solutions on grid integration and social and economical profitability is now started 7. Intense dissemination activities were carried out in (23 conference presentations, 5 scientific publications, 4 conference proceedings) 26

27 Contacts Christian-Eric BRUZEK Adela MARIAN Frédéric LESUR Follow us 27