CLP s first 400kV XLPE cable application

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Catherine Waters
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1 CLP s first 400kV XLPE cable application Chris Cheung CLP Power Hong Kong Limited 9 October 2017 Information Classification : PROPRIETARY Information Classification : PROPRIETARY

2 Project Requirement Due to erection of a new generation unit in Black Point Power Station, a new 400kV cable outlet is required to connect the generator transformer and 400kV switchgear. ~ New generation unit Transformer 400kV cable and SF 6 gas insulated sealing ends 400kV switchgear Information Classification : PROPRIETARY Page 2

3 Design Consideration Cable Insulation: Fluid-filled versus XLPE CLP adopts fluid-filled cable in 400kV network With significant improvement in XLPE cable insulation technology, o 400kV or even higher voltage XLPE cable has emerged o EHV XLPE cable has achieved a high level reliability Advantages of XLPE cable over fluid-filled cable system o simpler in cable manufacturing o environmental friendly o simpler design and easier installation for cable accessories EHV XLPE cable has a lower Total Life Cycle Cost than fluid-filled cable Information Classification : PROPRIETARY Page 3

4 Design Consideration (Cont d) Supply Base o The supply base of EHV fluid-filled cable system is diminishing while that of extruded insulation cable system is expanding o Cable suppliers are capable to supply 400kV or above XLPE cable and accessories Utility Practice o Many utilities adopt EHV XLPE cable system when developing new transmission network due to confidence on its reliability o The performance of EHV XLPE cable system in overseas utilities is satisfactory Safety, Health and Environment Considerations o The XLPE cable provides a simpler and cleaner cable system in terms of installation and jointing environment o Without the oil pumping facilities, the required area for XLPE cable system Information Classification : PROPRIETARY Page 4 installation is less

5 400kV Cable System Design Recent study shows that 400kV XLPE cable insulation thickness ranges from 26mm to 30mm XLPE insulated, lead-sheathed and MDPE oversheath cable, in compliance with IEC standard SF 6 gas insulated sealing ends, in compliance with IEC standard 400kV pre-moulded cable joint purchased as spare parts for future O&M Information Classification : PROPRIETARY Page 5

400kV XLPE Cable vs Fluid-filled Cable Conductor Conductor screen Insulation Insulation screen Water blocking tape Lead sheath MDPE oversheath Duct Conductor Conductor screen

6 400kV XLPE Cable vs Fluid-filled Cable Conductor Conductor screen Insulation Insulation screen Water blocking tape Lead sheath MDPE oversheath Duct Conductor Conductor screen Insulation Insulation screen Conductive tape Lead sheath Bedding Oversheath Binder Reinforcement 400kV XLPE Cable 400kV Fluid-filled Cable Information Classification : PROPRIETARY Page 6

7 400kV XLPE Cable Supplier Selection Supplier sourcing for 400kV system with the following consideration: Competent suppliers from Europe and Asia Equipment quality Supply track record Cost After-sales service Manufacturing capability Information Classification : PROPRIETARY Page 7

8 Quality Assurance a) Prequalification test of cable system completed on similar system b) Factory visit by CLP and factory quality system audit by consultant c) Design approval by CLP d) Type test to IEC by cable supplier (report issued by independent party) e) Type test, routine test and sample test witnessed by CLP and consultant f) Jointing skill transfer on 400kV cable accessories by cable supplier Information Classification : PROPRIETARY Page 8

9 400kV XLPE Cable Application in CLP Network CLP uses 400kV fluid-filled paper insulated cable in the power network To adopt 400kV XLPE cable in diversion / repair, 400kV transition joint is required to connect XLPE cable to fluid-filled cable However, the supply base of 400kV transition joint is limited and the maturity of technology is not proven yet Transition joint has a complicated design Only one supplier completed relevant type test and prequalification test with a few joints commissioned in 2016 Information Classification : PROPRIETARY Page 9

10 Conclusion EHV XLPE cable system becomes mature over the years in terms of the design, materials, manufacturing technology, testing and prequalification procedures. CLP will adopt 400kV XLPE cable system for new installation of 400kV cable circuit. Since the supply base of 400kV transition joint is limited and the technology is not proven yet, use of XLPE cable in CLP network for O&M is to be assessed with respect to the reliability and supply base of the transition joint. Thank You Information Classification : PROPRIETARY Page 10

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