© ABB Power Technologies. Power Systems DC -1 HVDC applications. triggered (LTT)for thyristor (ETT)andLight- Electrically triggered A comparisonbetween abb.com/hvdc HVDC ETT vs.LTTfor © ABB Power Technologies Power Systems DC -2- Thyristor triggering inHVDCapplications ! ! ! Electrically triggered thyristor(ETT) The TCU protects andmonitors theETT triggering isinitiated The TCU is energizedby unit (TCU). The ETTistriggered by FP IP TCU by anoptical pulse thethyristorcontrol the maincircuit, and pulse IP =Indicating FP =Firingpulse ! ! ! ! The TMU monitors theLTT Separate recovery The LTTisself-prote The LTTistriggered dire Light-triggered thyristor(LTT) FP protection isprovided cted againstovervoltage ctly byanopticalpulse TMU IP © ABB Power Technologies Power Systems DC -3- Thyristor andwafer center ofthewafer center The thyristorgateislocatedinthe ! ! ! ! IGBTs and GTOs advanced components like for necessary andis , Electrical triggering external light-guide connector inorder to guide ofglassand The LTTgateneeds aninternallight- cable andahermetic feed-through control cable via asimple electrical The ETTgateconne control (ETTs)oroptical(LTTs) The gateisdesignedf an externaloptical is mainstreamfor cts totheouter connecttothe or eitherelectrical © ABB Power Technologies Power Systems DC -4- T sLTTincommercialHVDC installations vs ETT ! ! ! ! Highest voltage rating8.8 kV TCU Precise external overvo yield encapsulation andtest 10 majorwaferproces gate signal Simple gatedesign gate contact gate Electrical T LTT ETT because ofpowerful amplifying gate amplifying Single-stage sing steps.Standard ing. High production ltage protection in ! ! ! ! Highest voltage rating8 kV protection withl Temperature dependent yield encapsulation andtestin 16 majorwaferprocessing power Complicated gatedesign Light Multi-stage amplifying gate amplifying Multi-stage Light-sensitive region and region Light-sensitive overvoltage protection overvoltage arge production spread Anode g. Reduced production internal overvoltage duetolowoptical steps.Morecomplex Cathode © ABB Power Technologies Power Systems DC -5- Thyristor Control Unit (TCU)forETT ! ! ! ! Old typeofTCU disturbances prone to Not encapsulated - firing Pre-charging neededfor included incircuitboardelectronics High voltage/high power components Discrete components design )*) *) ! ! ! ! *) are of thesame scale ABB design ABB The photographs metallic housing Totally encapsulated in operating conditions firinginall Ready for Only lowvoltage technique: Hybrid components ! ! High reliability Compact layout © ABB Power Technologies Power Systems DC -6- Features oftheABB typeTCU ! ! ! ! ! ! Standard features: On-line indication incase ofprotective firing On-line monitoring of thyristor levelblocking ability sufficient c Low light powerrequirement for overvoltages: Protective triggering againstthyristor energization, even directly triggeringinalloperational Ready for Quickly energizedfromthemain ci ! ! ! Transient forwardovervolt Very fastrate-of-rise ofthevo Overvoltage inforw ard blockingstate after anetworkfault after age duringrev ltage inforwardblocking state ontrol. Light emitting are ontrol. Light emittingdiodes are rcuit, evenbyalightningimpulse conditionsdueto theveryfast erse recovery ! ! ! thyristor levelconditions suchas On-line supervisionofspecific Optional: Thyristor temperature Optical performance circuitimpedance © ABB Power Technologies Power Systems DC -7- Thyristor levelelectronics LTT Monitoring Unit: ! ! ! ! ! of thesame scale. are approximately The circuitboards 8 100 unityears experience (endof2004): Estimated commercialoperation additional module Recovery protectionnotincluded joints solder Approximately 130 voltagegrading DC Thyristor voltagemonitoring electronics needed components and280 " ! ! ! ! The ABB Thyristor Control Unit: ABB ETTvs.LTT 350 000unityears experience (endof2004): Estimated commercialoperation 100 solderjoints Approximately 40components and Thyristor performance monitoring Normal andprotectivefiring (45000units) © ABB Power Technologies Power Systems DC -8- ETT andLTToptical systems ! control unit Valve For 12thyristors: ETT system ! ! ! at valvepotential 24 optical at ground level 24 optical 24 lightguides Valve potential Valve potential Valve potential Valve connectors connectors Thyristor level control unit control Valve LTT systemwithexternalrecovery ! For 12thyristors: ! ! ! at valve potential 45 optical at ground level 17 optical 31 lightguides Thyristor level Thyristor coupler Optical star protection connectors connectors Grading 100 kV component redundant Non- star coupler star optical To next Laser Laser Electronics, © ABB Power Technologies Power Systems DC -9- h B ot-knts av ihLTTs The ABBKonti-Skan testvalvewith ! ! The 7kV,45 cm during off-state andrecovery Built-in overvoltage protection Directly light-triggered 2 thyristor ! ! ! ! The 125kV,1050Atestvalve Two typesoflightsourcestested: inseries LTTs 48 valve 1988, replacingamercuryarc In commercialoperationsinceMay ETT concept advantage incomparison withABB’s Technically functioning, butno ! ! of thyristorsvia op Powerful laserdi Light-emitting diodes odes servinggroups tical star couplers , oneperthyristor © ABB Power Technologies Power Systems DC -10- ABB convertervalves forHVDCtransmission ABB hasselected theETTapproach transmission Converter valves inth for superiorperformance e Three Gorges-Changzhou © ABB Power Technologies Power Systems DC -11- hrceitc fteABslto ihETTs Characteristics ofthe ABBsolutionwith ! ! ! ! ! ! Robust thyristor design Low riskofcommutation failures thyristor) system, electronics,or Full redundancyincaseof interval 5yearsformoderninstallations. Low maintenancerequirement Proven highreliability High-tech solution for thyris High-tech solution for ! failure duringcommerci with5”wa ETTs 14 000 al operationreported. fers installed(end a componentfailure(optical tor triggeringandprotection tor s. Scheduledmaintenance 2004). Nothyristor © ABB Power Technologies Power Systems DC -12- Conclusions Electrically triggeredthyristors aresuperior! ! ! ! design withlowercomplexity The ETTconceptisarobust andreliable The LTTconceptisatechnological dead-end ABB has ! ! 1988 for HVDCduring17yearssince LTTs tested for HVDCsince1967 ETTs used www.abb.com/hvdc