ACCELERATED ELECTRICAL AND MECHANICAL AGEING TESTS OF HIGH TEMPERATURE LOW SAG (HTLS) CONDUCTORS

Transcription

1 27-April-7 ACCELERATED ELECTRICAL AND MECHANICAL AGEING TESTS OF HIGH TEMPERATURE LOW SAG (HTLS) CONDUCTORS Dominik Stengel, Richard Bardl (BAM) Christian Kühnel, Steffen Großmann (TU Dresden) Wilhelm Kiewitt (Hertz)

2 The idea Expansion of transmission system Uprating of transmission lines HTLS conductors Higher capacity due to higher rated temperature - Lower sag (thermal expansion) - Temperature resistant materials Limited long-term experience! Material degradation? (RTS, electrical resistance, creep ) 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 2

3 Selected conductors conductor Core material Outer layers Structure ACSR Steel Hard drawn aluminum ACCC, ACPR ACCR GZTACSR Gap Polymer matrix composite Metal matrix composite Steel Annealed or thermal aluminum Thermal aluminum Thermal aluminum Also tested: ACSS, ZTACIR, TACSR 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 3

4 Conductor ageing Reality ( years) Everyday stress, wind loads Thermal and electrical loads Corrosion (temperature, environment) Laboratory (6 months) Tensile force Maximum rated and emergency temperature not studied 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 4

5 Tensile force Applied tensile force = Static load + Cyclic load Static load (Everyday stress) - Calculated for an ideal single span of 43 m and 5.5 m sag ca. 5 % RTS (depending on the conductor s specific weight) 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 5

6 frequency in years frequency in years v b in m/s v b in m/s From wind velocity to tensile force Wind velocities in years According to EN (0 m height, wind zone 2, rural terrain) v b vin m/s b in m/s cumulative cumulative frequency frequency for for years years 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 6

7 frequency in years frequency in years v b in m/s v b in m/s From wind velocity to tensile force v vin in m/s m/s b b Wind velocities in years cumulative cumulative frequency frequency for for years years 5 classes of wind speeds 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 7

8 frequency in years frequency in years v b in m/s v b in m/s From wind velocity to tensile force v vin in m/s m/s b b Wind velocities in years cumulative cumulative frequency frequency for for years years 5 classes of wind speeds Turbulent wind field based on provisions Generation of a 0 minutes wind field 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 8

9 frequency in years frequency in years v b in m/s v b in m/s From wind velocity to tensile force v vin in m/s m/s b b Wind velocities in years cumulative cumulative frequency frequency for for years years 5 classes of wind speeds Turbulent wind field based on provisions Tensile force on conductor based on FE simulation Validated FE-model for existing overhead line in Northern Germany 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 9

10 frequency in years frequency in years v b in m/s v b in m/s From wind velocity to tensile force Wind velocities in years classes of wind speeds Turbulent wind field based on provisions Tensile force on conductor based on FE simulation Defined cyclic tensile force v vin in m/s m/s b b cumulative cumulative frequency frequency for for years years - Equivalent harmonic forces with defined mean, amplitude and number of cycles using rainflow count - Reduction to 3 cyclic loads and amplitudes using Palmgren-Miner 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 0

11 Cyclic loading for ACSS (RTS = 56 kn) x days at 0 C Minimum load [kn] Maximum load [kn] Number of cycles Static loading Constant Wind load ,780 Wind load Wind load May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors

12 Testing rack for artificial ageing - Test of 4 different conductor types simultaneously in two parallel lines - Conductor length of approximately m 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 2

13 Testing rack in Ragow (Germany) 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 3

14 Conductor tests Single wire stress strain Conductor stress strain Ductility test on wires Grease test Creep Selfdamping Electrical resistance (TU Dresden) Electrical and mechanical accessories tests 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 4

15 Test result: Tensile strength of aluminum - Ageing 00 h at 20 C, 0 h at 2 C - ZTAL (AT3, aluminum-zirconium-alloy) Sample Standard New AT3 Aged AT kn 2.58 kn.75 kn kn 2.49 kn.73 kn kn 2.36 kn.78 kn - Tensile strength decreased of 29 % after ageing 8-May-7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors Workshop 5

16 Summary Scientific development of an artificial ageing regime Successful implementation in a test stand Ageing of 8 different conductor technologies Extensive mechanical and electrical test program prior and after ageing First test results show interesting ageing effects Overall results expected at the end of 7 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 6