Advanced Materials for Overhead Line Reconductoring

Transcription

1 1 Advanced Materials for Overhead Line Reconductoring How Modern Conductors are Improving the Efficiency, Capacity, Reliability and Resilience of the Electric Power Grid Dave Bryant, Director Technology CTC Global Corporation

2 2 Evolution of Overhead Conductors Copper Conductor + Great conductivity & decent strength (~48 ksi) - Heavy, expensive, and material ultimately diverted to war effort (WWI) All Aluminum Conductor (AAC) 1350 H19 + Good conductivity ~61% IACS (annealed copper standard) - Relatively weak ~26 ksi / limited span lengths / thermal limits Aluminum Conductor Alloy Reinforced (ACAR) 1350 H19 / 6201 T81 + Decent conductivity ~61% / 52.5% with improved core strength ~47 ksi - Thermal / sag limits, decreased efficiency (increased line losses) All Aluminum Alloy Conductor (AAAC) Improved overall strength ~47 ksi - slightly reduced conductivity ~52.5% - Thermal / sag limits, decreased efficiency (increased line losses) Many variations >

3 3 The Industry Standard Aluminum Conductor Steel Reinforced (ACSR) + Good conductivity ~61% (strands), improved strength ~210 ksi (core) - Some weight penalty, steel core may be susceptible to corrosion - Thermal (and sag) limits - limit ampacity ACSR has represented the benchmark standard conductor for over 100 years

4 4 Primary drivers for improved conductor designs Reconductoring is far easier than building new lines New conductor designs can increase capacity from 1.5 to 3X Greater capacity can mitigate grid congestion & sag violations, while enabling the integration of new generation resources Modern conductors can reduce capex on new lines greater spans between fewer and/or shorter structures Improved efficiency reduces operating costs (inc. fuel & emissions) Modern conductors can improve longevity and grid resilience as they offer better resistance to cyclic load fatigue, corrosion and impact. Composite core & conductor undamaged Composite core survival helped expedite repairs

5 5 High temp conductors developed to increase line capacity ACSS + Pre-annealed aluminum enabled higher temperature operation + Improved conductivity (~63% IACS vs ~61% for 1350 H19) + 2x capacity of ACSR, AAC, AAAC, etc. - Some reduction in strength (1350-O aluminum = ~8.5 ksi) ACSS-TW + Decrease cross-sectional area (to reduce wind / ice loads) or add aluminum content (to reduce electrical resistance) + 2x capacity of ACSR, AAC, AAAC, etc. - Added aluminum increases weight ACSS HS Higher strength steel core makes up for weaker annealed aluminum + Available in round or trapezoidal designs in virtually any size + 2x capacity of ACSR, AAC, AAAC, etc. > ACSS conductors are capable of operating above 200 C under N-1 conditions *ACSS HS285 is a trademark of Southwire

6 6 Novel Conductors GAP (GTACSR or GTZACSR) Developed by J Power (Sumitomo) in Gap conductor consists of steel core strands surrounded by a small gap filled with temperature resistant grease, surrounded by an initial trap or z-shaped layer and either round or other wires. Over 25,000 km produced by JPower. Available in various temperature ranges (Now produced by many other suppliers) + GAP design offers improved sag performance (low thermal knee-point) X capacity of ACSR - Installation requires specialized technique and cannot be spliced - Grease can create environmental issues and increase corona.

7 7 Novel Conductors ACIR (Invar core) Developed by JPower (Sumitomo) in Invar conductor consists of multiple aluminum-clad Invar (Nickel-Iron alloy) core strands wrapped with aluminum-zirconium alloy strands. Over 8,000 km produced by JPower. (Also available from other suppliers) + Invar core offers a very low coefficient of thermal expansion to mitigate thermal sag X capacity of ACSR - Relatively high cost as Invar is more expensive than steel and also requires aluminum coating to resist corrosion. - Not as efficient as other designs due to magnetic hysteresis losses.

8 8 Composite Conductors ACCR Developed by 3M. Uses a metal matrix composite core consisting of aluminum with alumina fiber reinforcement and aluminum-zirconium alloy strands that resists annealing (available in round or trap wire designs). Introduced in ~2002 with an estimated 200 projects completed. + Great conductivity, light weight, improved corrosion resistance + 2x + capacity of ACSR - Bending limitations require proper handling during installation - Higher per unit cost compared to other conductor types (however, overall project costs may be lower, especially for reconductoring)

9 9 Composite Conductors LoSag Developed by Nexans and introduced in ~2009. Consists of a single allcarbon fiber core embedded in a thermoset resin protected by a thermoplastic sheath and aluminum sleeve, wrapped with z-shaped aluminum-zirconium strands. + Carbon fiber core offers high strength, light weight and a very low coefficient of thermal expansion to mitigate thermal sag + 2x capacity of ACSR - Bending limits require proper handling during installation - Very little information is currently available (only a handful of projects) please contact Nexans for more information

10 10 Composite Conductors C7 Developed by Southwire and Celanese and introduced in ~2013. Consists of seven individual all-carbon fiber core strands each embedded in a thermoplastic resin and protected by a thermoplastic sheath, wrapped with fully annealed aluminum or aluminum-zirconium alloy strands. + Carbon fiber core offers high strength, light weight and a very low coefficient of thermal expansion to mitigate thermal sag + 2x capacity of ACSR - Bending limits require proper handling during installation - Very little information is currently available (only a handful of projects) please contact Southwire for more information

11 11 Composite Conductors ACCC Developed by CTC Global. Commercialized in authorized manufacturers. Consists of a single carbon and glass fiber core embedded in a thermoset resin, stranded with Type 1350-O annealed trap wires. Over 600 projects completed or in process + Carbon fiber core offers high strength, light weight and a very low coefficient of thermal expansion to mitigate thermal sag + 2x capacity of ACSR - Bending limits require proper handling during installation - Heavy ice load areas require the use of more expensive ULS version core (375 ksi) and/or aluminum-zirconium strands).

12 12 Material / Conductor Comparisons Description Aluminum Conducting Materials Name Conductivity (%IACS) Tensile Strength (ksi) Max Cont. Op. Temperature (degrees C) Hard Drawn 1350-H MS Alloy 5005-H HS Alloy 6201-T Fully Annealed 1350-O Thermal Resistant TAL HS Thermal Resistant KTAL Ultra Thermal Resistant ZTAL / UTAL Extra Thermal Resistant XTAL Description Core Materials Weight (lbs/inch³) Modulus of Elasticity (msi) Tensile Strength (ksi) Coefficient of Thermal Exp. (x 10-6/ C) HS Steel EHS Steel EXHS Steel (Galfan coated) Carbon Hybrid Epoxy Alum Clad (20.3 IACS) Galv. Invar Alloy Mishmetal Std Mishmetal HS Al Oxide Metal Matrix Conductor Properties Conductive Strands Core Strands Code aluminum tensile conductivity Conductor Description Name type strength (%IACS) type tensile strength modulus CTE AAC All Aluminum Conductor 1350-H ksi H ksi 10 msi 23.0 AAAC All Aluminum Alloy Conductor 6201-T ksi T ksi 10 msi 23.0 ACAR Aluminum Conductor Al Alloy Reinforced 1350-H ksi T ksi 10 msi 23.0 ASCR Aluminum Conductor Steel Reinforced 1350-H ksi 61.2 coated steel ksi 29 msi 11.5 AACSR Aluminum Alloy Conductor Steel Reinforced 6201-T ksi 52.5 coated steel ksi 29 msi 11.5 ACSS Aluminum Conductor Steel Supported 1350-O ~8.5 ksi 63.0 coated steel ksi 29 msi 11.5 ACIR Aluminum Conductor Invar Reinforced Al-Zr alloy ksi 60.0 invar steel ksi 22 msi 3.7 ACCR Aluminum Conductor Composite Reinforced Al-Zr alloy ksi 60.0 metal matrix 200 ksi 32 msi 6 ACCC Aluminum Conductor Composite Core 1350-O ~8.5 ksi 63.0 carbon hybrid ksi msi 1.6

13 13 Composite Conductor Core Compositions ACCR Metal Matrix Composite Core ACCC Composite Core (Multiple strand design) C7 LoSag (Single strand design) >1,000,000 carbon & glass fibers (3/8 core size)

14 Cable Sag (Inches) Sag Comparison 0 Temperature (C) ACCC GAP Invar ACCR ACSS ACSR Comparison testing performed by Hydro One on a 65 meter span, 1600 amps, Drake size

15 15 Project Example Description: 240 circuit miles, 345 kv line, double bundle Project: replace 1,440 miles of ACSR conductor with ACCC Objectives Improve reliability (less sag and corrosion) Increased capacity to serve growth Retain existing structures to reduce costs Eliminate down time with Live Line Reconductoring Additional Benefits Project completed eight months ahead of schedule Reduced line losses by 30% Saving $15 million/yr. (300,000 MWh at $50) Reducing CO2 emissions by ~200,000 metric tons per year (= 34,000 cars off the road) Freed up ~28 MW of generation

16 16 Summary Copper, AAC, AAAC, ACAR & ACSR are all good conductors, each offering various benefits ACSS offers increased line capacity when clearances allow Novel and Composite core conductors offer great alternatives when your project requirements include: Need for increased capacity when sag is an issue Desire to reduce operating and maintenance costs Aspiration to improve line efficiency, capacity & reliability Requirement to improve grid resilience

17 Questions? New 50 km 275 kv triple bundle ACCC conductor generation tie line energized in Malaysia July, 2017 Please Dave with additional questions