Close and Return A.3.6 8th International Conference on Insulated Power Cables A.3.6 DEVELOPMENT, QUALIFICATION AND EXPERIENCES WITH 500 KV XLPE CABLE SYSTEMS Johannes KAUMANNS, Andreas WEINLEIN, Gero SCHRÖDER, Südkabel GmbH, Volker STROOT Südkabel GmbH Mannheim (Germany) [email protected], [email protected], [email protected], [email protected] ABSTRACT 10 years after the first installation of a 550kV XLPE cable system in China, an advanced system has been developed and qualified. The XLPE cable system consists of a cable with a conductor cross section of 2500mm², one piece silicone rubber joint, plug-in GIS termination, plug-in dry type outdoor termination and compound filled outdoor termination with composite insulator. Both, the type test and pre-qualification test have been carried out according the IEC62067 requirements Additionally, tests with increased AC and impulse levels has been carried out. The new cable system has been installed successfully at projects in Sudan, China, Columbia, Russia and other locations. These experiences demonstrate that 550kV XLPE cable systems are state-of-the-art technology. KEYWORDS 500 kV XLPE cable system, one piece silicone rubber joint, PD monitoring system, plug-in compact sealing end, PQ test INTRODUCTION 10 years after the first installation of a 550 kV XLPE cable system in China in the year 2000 [1], an advanced system has been developed and qualified. The above mentioned first 550kV systems were primarily designed for short cable connections inside power plants, but with increasing need for longer cable systems an advanced system became necessary for higher transmission loads and longer cable length for the 500kV voltage level as described in [2]. installation conditions of the cable (buried installation, pipe installation and clamped installation). Additional PD tests has been carried out during the full test duration and highlevel impulse tests with 1675 kV BIL demonstrate the dielectric performance of the cable. All qualification tests have been carried out at the independent testing institute IPH / CESI in Berlin (Germany). Further tests with a compact plug-in sealing end installed inside the oil immersed transformer cable connection enclosure of a 500 kV transformer were carried out in 2010 in a factory installation Powertech Transformers (Pty) Ltd Pretoria (South Africa). Additional dielectric tests with increased testing parameters (AC and impulse) have been carried out with GIS-terminations at the IEH testing institute in Karlsruhe (Germany) The new cable system has been installed successfully and went into operation around the world, in North Africa, China, Colombia, Russia (at voltage level 550 kV) and other locations demonstrating the progress and experiences in this voltage level under different installation conditions. These experiences show that 500 kV XLPE cable systems are state-of-the-art XLPE cable technology. ADVANCED 550 KV XLPE SYSTEM The qualified XLPE cable show a six segmental copper conductor with a cross section of 2500 mm². The EHVgrade XLPE insulation material shows a thickness of 27mm and was applied by triplex extrusion process together with both semicon layers in a horizontal extrusion line. Figure 1 shows details of the cable design: The new EHV cable system shows an XLPE isolated cable with a conductor cross section of 2500mm² and prefabricated accessories of the newest generation: One piece silicone rubber joints, compact SF6-plug-in sealing ends, plug-in dry type outdoor sealing ends and compound-filled outdoor sealing ends with composite insulators. The main parameters of the pre-qualified cable system are: • • 550 kV voltage level Um: conductor cross section (copper / segmental): 2 2500 mm • XLPE insulation thickness of cable: 27 mm The type test has been carried out according the IEC 62067 [5] requirements for the Umax = 550 kV level. The one year prequalification (PQ) test covers different 1 conductor copper, RMS, 6 segments 2 conductor screen Conductive XLPE-compound 3 insulation XLPE 4 insulation screen Conductive XLPE-compound 5 bedding swelling tape, semi-conducting 6 wire screen copper screen wires 7 bedding semi-conducting swelling tape 8 bedding fabric tape, semi-conducting 9 metallic sheath 10 outer sheath Co-polymer-laminated aluminium foil HDPE, two outer layers conductive and flame-retardant Fig. 1: Cable design for type and PQ test The copper wire screen design is longitudinally watertight and the laminated aluminium foil design delivers a save radial water protection to the cable under all installation conditions. A strong HDPE outer jacket, which is fix bonded to the aluminium foil, provides the mechanical protection of the cable. The well known compact sealing end of type EHSVS 550 (type F) was taken as SF6 termination. The outside Jicable’11 – 19 – 23 June 2011, Versailles - France Close and Return A.3.6 8th International Conference on Insulated Power Cables dimensions are according to the actual IEC 62271-209 standard. This plug-in termination provides an absolute dry solution without any liquid or gaseous contents. If taking into account the needed space below the GIS switchgear during the installation and lifting of the termination during the installation work the cable installation work can be done separately from GIS work. A.3.6 from glass fiber reinforced epoxy resin provides a good mechanical protection for the joint main insulation body. A top cover allows an easy installation of a cross bonding cable if needed. Fig. 5: 500 kV one piece joint TYPE AND PQ-TEST The type test set-up consists of the above mentioned XLPE cable, one–piece silicone-rubber joint, compact OSE and compound filled OSE. (See picture below) Fig. 2: 500 kV compact SF6 sealing end Two type of outdoor sealing ends have been type tested: The well known SF6 filled type with plug-in connection [3] and a compound filled design with prefabricated stress cone (Fig. 3, left). The gas filled type can be pre-mounted and pre tested in the factory and allows a shortened installation time on-side (Fig. 4). On the other hand the compound filled type shows an SF6 free solution. The heart piece of this type is the prefabricated stress cone made from silicone rubber. Fig. 6: set-up of 500 kV type test The compact SF6 sealing end of type EHSVS 550 (type F) has been successfully type tested for the 550kV level with the identical cable type since 2004 [3]. Fig. 7 (left): 500 kV type test – entire set-up Fig. 8 (right): 500 kV type test – one piece joint Fig. 3 (left): 500 kV compound filled OSE (stress cone) Fig. 4 (right): 500 kV compact gas filled OSE The testing parameters were chosen according the IEC 62067 standard (e.g. AC testing voltage 580kV, 20 load cycles 95°C – 100°C, 1550kV BIL, 1175kV SIL). The tests have been successfully carried out at IPH testing institute in Berlin /Germany (CESI group). The joint type is a one piece pre-molded joint. The main insulation body is made from silicone rubber (SiR) with integrated field control electrodes. An insulation section is integrated in the outer conductive layer of the joint to provide the screen separation when applied as cross bonding joint. The one year pre-qualification (PQ) set-up shows additionally two compact SF6 sealing ends of type EHSVS 550 and 100 m cable length of the above mentioned cable. The cable and joint were installed buried (see pictures below). Additionally, one section of the cable has been installed in a pipe. The outer corrosion protection is given by a coffin box filled with an insulation compound. The coffin box made Jicable’11 – 19 – 23 June 2011, Versailles - France Close and Return A.3.6 8th International Conference on Insulated Power Cables A.3.6 Fig. 9: Set-up of 500 kV PQ test Fig. 15: 500 kV PQ test – entire set-up at –20°C The following figures show the a typical load cycle and the measured temperatures on cable jacket, dummy conductor, dummy jacket, load current, dummy current, and the applied voltage. Fig. 10 (left): 500 kV PQ test - cable laying Fig. 11 (right): Back filling of pipe-laying installation Fig. 12: Compact SF6 sealing ends of type EHSVS550 Fig. 13: One-piece SiR joint SEHDVCB550, buried In order to monitor all relevant temperatures a total of 24 temperature sensors has been used (see next figure) at both, the dummy circuit and distributed along the cable circuit under test. The following figure gives the total overview of the PQ test arrangement. Empfäng$r an Schrank TS7 -A7 -A6 T01 LD1 ASA RX30 T02 MD1 T1 T2 T3 T4 T09 MT1 ASA RX30 MD3 MD5 T03 T04 15B4 T05 LD2 N ASA RX30 T2 T3 T4 17B0 T06 MD2 T1 T2 T3 T4 MD4 MD6 T07 T08 15B5 Dummy T13 MT5 ASA RX30 T2 T4 T1 T2 T3 T4 MT11 MT12 T19 T20 ASA TX30 17B8 T14 MT6 T1 MT7 T15 ASA RX30 MT4 T12 T3 17B4 -A8 T17 T18 MT9 MT10 T10 MT2 T1 MT3 T11 ASA RX30 T1 T2 T3 T4 MT15 T23 MT8 T16 Endv$rschluss EHFVC 550 fr$i fr$i 17B1 11639/08 11641/08 TS7:MT2 T10 TS7:MT1 T09 Endv$rschluss EHFVC 550 17BC Hauptschl$if$ Hauptschl$if$ M2 11627/08 ASA TX30 11628/08 ASA T X30 ASA TX30 17B0 11638/08 11640/08 T21 T22 MT13 MT14 M8 TS7:MT15 T23 th Fig. 16: 156 load cycle T on buried cable 17BB 11610/08 11613/08 T20 TS7:MT12 17BE TrafoSt$u$rung T21 TS7:MT13 ASA T X30 17BA 11470/08 11477/08 11469/08 11471/08 ASA TX30 Trafo 17BC TS7:MT1 1 T19 Muff$ VMSVS 550 ASA TX30 17B9 11630/08 11631/08 ASA TX30 17B8 11623/08 11625/08 TS7:MT10 T18 TS7:MT9 T17 M3 11634/08 11635/08 M6 ASA T X30 17B2 TS7:MT3 T11 Muff$ SEHDVCB 550 11622/08 11624/08 ASA T X30 17B3 TS7:MT4 T12 T22 TS7:MT14 11619/08 T15 TS7:MT7 11642/08 17B6 11645/08 11632/08 11633/08 TS7:MT8 T16 M7 11618/08 ASA TX30 T13 TS7:MT5 ASA TX30 11643/08 17B4 ASA TX30 17BD ASA TX30 11626/08 11644/08 ASA TX30 17B7 11629/08 TS7:MT6 T14 (4)15B4 Z$lt H$iztrafos ASA T X30 TS7:LD1 T04 T01 TS7:MD5 11159/06 11160/06 T02 11621/08 11614/08 T03 TS7:MD1 TS7:MD3 17B5 11612/08 11611/08 ASA TX30 M5 ASA TX30 fr$i: Rittal-Schrank Anschlußkast$n Polycarbonat 17BF Anschlußsäul$ BEWAG (4)15B5 M4 2 x Kunststoff-Rohr di = 200 mm x 2 m 11636/08 11620/08 11617/08 11615/08 M1 Dummy l = 15 m Fig. 17: 156th load cycle T on dummy 11609/08 TS7:MD4 11616/08 T0711606/08 11164/05 10402/99 TS7:MD6 T05 T08 TS7:LD2 TS7:MD2 T06 11637/08 V$rsuchsaufbau Südkab$l 1524.2081038 Lag$ d$r T$mp$raturm$ßst$ll$n (nicht maßstäblich) Stand 17.03.2009 Fig. 14: positions of 24 pcs. temperature sensors The PQ test were running under all whether conditions down to temperatures at –20°C (see picture 15). All accessories were equipped with inductive type PD sensors. Omicron type pick-up sensors were used for regular PD measurements whereas IPEC type sensors were used for a long term monitoring of the PD activities during the PQ test (see pictures below). During the test no PD from the testing objects could be observed. Jicable’11 – 19 – 23 June 2011, Versailles - France Close and Return A.3.6 8th International Conference on Insulated Power Cables A.3.6 - SHORT CIRCUIT CURRENT TESTS: The contact system of thew compact sealing end was tested by short time withstand current of 63 kA for 3 sec. with 170 kA peak current. The tests were passed successfully without any recognized effects on the plug-in contact system (see picture 25). Fig. 18 (left): inductive sensors at back-to-back joint Fig. 19 (right): inductive sensor at OSE After the PQ test has passed 180 load cycles (90°C 95°C) and 8570 h AC voltage the final impulse tests has been carried out on cable samples. After successful passing the IEC requirements BIL test: 1550 kV SIL test 1175 kV an increased impulse test with 1675 kV was passed. Finally, the investigation of all accessories has been performed in terms if any deteriorations were visible (see pictures below). The inspection was without any findings. Fig. 20 (left): 500 kV PQ test – investigation joint Fig. 21 (right): 500 kV PQ test – investiagation OSE ADDITIONAL QUALIFICATION TESTS Beside the required tests according the IEC 62067 standard additional tests have been carried out: Fig. 24 (left): Set-up three phase 63 kA / 3 sec. Fig. 25 (right): Common plug-in SE contact after test - ADVANCED DIELECTRIC TESTS Sample tests with increased testing levels have been carried out with the compact termination system consisting of SF6 sealing end of type EHSVS and compact OSE of type EHFVCS and a 500 kV cable (Fig. 26). The passed testing levels were: Lightning impulse voltage: 1675 kV Switching impulse voltage: 1240 kV AC testing voltage: 640 kV / 1h - DIELECTRIC TESTS WITH PORCELAIN INSULATOR With the requirement to use porcelain type insulators for special applications the compact OSE was tested accordingly (see picture below Fig. 27). - TESTS OF THE TRANSFORMER SEALING END The transformer sealing end of type EHTVS 550 shows the identical design to the compact SF6 sealing end. Only the connection interface to the internal transformer link shows an additional HV electrode to shield the connection area. The plug-in end sealing end was installed head first in a transformer cable box and dielectrically tested (see picture) in an oil immersed environment. The AC testing voltage was 493kV accompanied by PD measurements. After AC test transient testing voltages according to the BIL and SWIL were applied. The testing voltage was applied by a compact OSE (see picture below) to the set-up. Fig. 22 (left): Set-up transfromer 550 kV cable system Fig. 23 (right): 550 kV transformer compact SE Fig. 26 (left): Sample test with increased voltages Fig. 27 (right): Tests of 500 kV compact porcelain OSE - SHORTENED PQ-TEST WITH JOINT IN AIR Fig. 28: Shortened PQ-test of outdoor installed joint Jicable’11 – 19 – 23 June 2011, Versailles - France Close and Return A.3.6 8th International Conference on Insulated Power Cables A.3.6 In order to verify installation in air of the joint 104 load cycles at 500kV, (approx. 5000 h voltage) were applied to the one-piece silicone-rubber joint (see picture above) of type SEHDV550. The joint passed the test and the final investigation gave no hint for any deteriorations. ON-SITE INSTALLATIONS (EXAMPLES) The new cable system has been installed successfully and went into operation around the world, in North Africa, China, Colombia, Russia (all for voltage level 500 kV) and other locations demonstrating the progress and experiences in this voltage level under various installation conditions. The next pictures show some relevant references: - 500 kV transformer connection to GIB In this application the cable is installed headfirst to the transformers cable box: Fig. 31: Installed one piece joint SEHDVCB - porcelain insulators with compact OSE For special dry climate pollution conditions customers require porcelain insulators. Fig. 29: 15 pcs. 500 kV compact transformer SE - Connection to GIB: A typical vertical installation of the compact SF6 sealing end is shown in Fig. 30: Fig. 32: EHV compact OSE with plug-in technology and porcelain insulators For cold climate conditions below –30°C a special heating system has been developed to enable low temperature operation of the compact OSE (Fig. 33). Fig. 30: GIB-compact SF6-plug-in SE - typical joint installation: The joint installation requires a concrete bottom for installation the needed cable clamping beside the joint to take the mechanical forces from the cable away from the joint. Fig. 33: 500 kV compact OSE with external heating for lower temperatures Jicable’11 – 19 – 23 June 2011, Versailles - France Close and Return A.3.6 8th International Conference on Insulated Power Cables - typical compact OSE installation The pre-fabricated insulator part allows an short time installation work on-site [3] as it can be pre- tested and fully pre-assembled shipped to the installation site. The installation work can be widely reduced to the installation of the plug-in part only. A.3.6 CONCLUSIONS An advanced 500kV XLPE cable system with prefabricated accessories and plug-in type terminations for conductor cross sections up to 2500 mm² has been developed and qualified. All qualification tests have been carried out according IEC 62067 standard. Additional qualification tests give evidence for higher dielectric withstand, short circuit current withstand and application under various installation conditions. This system has been successfully installed around the world at several projects for the 500kV level and demonstrate the state of the art technology of 500 kV XLPE cable systems. REFERENCES Fig. 34: 500 kV compact OSE with plug in technique in Colombia A new mobile and compact resonance testing system has been developed to carry out commissioning tests with increased AC voltages even at remote locations (Fig. 35, [4]). [1] staff report “First 525kV XLPE extra high voltage cables destined for Dachaoshan”, Modern Power Systems, December 2000, pp 39-41 [2] S. Sadler, S. Sutton, H. Memmer, J. Kaumanns “1600MVA Electrical Power Transmission with an EHV-XLPE Cable in the Underground of London”, Proceedings CIGRÈ 2004, no. B1-108, International Council on Large Electrical Systems (CIGRÈ), Paris, 2004 [3] J. Kaumanns, G. Schröder, A. Weinlein, V. Stroot, J. Lehnhäuser: 400 KV XLPE-Insulated cable systems with dry plug-in outdoor terminations, Jicable’07, paper A.1.2 [4] A. Weinlein, G. Schröder, H. Geyer, 2011, On-site testing with compact a.c. test-system at the first 500 kV XLPE cable project in South America, Jicable’11, paper C.4.1 [5] IEC 62067 Ed.1.1 2006-03, Power cables with extruded insulation and their accessories for rated voltages above 150 kV (Um = 170 kV) up to 500 kV (Um = 550 kV) - Test methods and requirements GLOSSARY Fig. 35: 500 kV AC on-site test ACTUAL CHALLENGES The actual challenge for the new cable system is a huge 500kV project Skolkovo in Moscow/Russia: The delivery consists of 70km XLPE cable with a conductor cross section of 2500mm² showing oxidised wires for reduced skin effect losses. A total of 180 buried joints (cross bonded type SEHDVCB 550) and 38 compact OSE of type EHFVS 550 with plug in technology have to be installed. AC (E)HV GIB GIS HFCT (O)SE PD PQ XLPE Alternating Current (Extra) High Voltage Gas Insulated Bushing Gas Insulated Switchgear High Frequency Current Transformer (Outdoor) Sealing End Partial Discharge(s) Prequalification Cross-Linked Polyethylene Order intake was early 2011 and commissioning is planned for 2011/2012. Jicable’11 – 19 – 23 June 2011, Versailles - France
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