SIMOVERT MV Medium-Voltage Drives 660 kVA to 9100 ... - Industry

SIMOVERT MVEngineering informationSystem componentsTransformersThe SIMOVERT MV drive converteris connected to the medium-voltagesystem via a driveconverter transformer. Thestandard12-pulse DFE requires a threewindingtransformer, theoptional 24-pulse DFE twothree-winding transformers orone five-winding transformer.When the transformer is implemented,the SIMOVERT MVdrive (converter and motor) isdecoupled and electrically isolatedfrom the mains supply:¦ The short-circuit power isthus reduced to a valuesmaller than max. permissible¦ The motor is operatedground-free¦ Low harmonic distortionthrough 12-pulse DFE.An insulation monitoring devicein the drive converter monitorsthe insulation status betweensecondary transformer windingand motor.Three-winding transformerThe secondary windings ofthe three-winding transformerhave a phase angle of 30 ° el.,resulting in 12-pulse infeedcombined with lower harmonicdistortion.Apart from electrical and thermalstress during converter-fedoperation, also the followingproperties have to be taken intoaccount when engineering thetransformer:¦ Impedance voltage V k :6% min.¦ Tappings for voltageadjustments:2 x ± 2.5% or ± 5% for operationwith output filter. Thewinding tappings are usuallylocated on the HV-side of thetransformer.¦ The secondary-side insulationvoltage is to be dimensionedfor the test voltagestated in the table on thefollowing page. The impulsestrength test voltage forreinforced insulation isspecified 1 ).Three-winding transformersfor drive converters withpower section in parallelcircuitThe infeed on the line side canbe carried out via a shared12-pulse transformer circuitfor both partial systems (seeFig. 6/12). Infeed is also possiblevia two separate 12-pulsetransformers (see Fig. 6/13).A 24-pulse supply can also beestablished by shifting the twotransformer phases through ±7.5 °.With the shared 12-pulse transformercircuit, commutatingreactors with V k W 2% mustbe used in the correspondingrectifier cable. If there is enoughspace, the reactors must befitted close to the transformer 2 ).Transformer secondary voltages and associated insulation requirementsRated voltage 2.3 kV; 3.3 kV; 4.16 kV; 6 kV; 6.6 kV 2 x 4.16 kV (with power section connected in parallel)Infeed 12-pulse 24-pulse 12-pulse 12- or 24-pulseInfeed viaPrinciple diagram1 Three-windingtransformer2 Three-windingtransformers 3 )1 Three-winding transformerand commutatingreactors(see Fig 6/12)2 Three-windingtransformers 3 )(see Fig 6/13)Recommendedvector groupConverterratedvoltagekVConverterratedpowerkVADy5 Dd0Transformersecondaryvoltage4 )kVDy5 Dd0 +7.5 ° phase shiftDy5 Dd0 –7.5 ° phase shiftTransformersecondaryvoltage4 )kVDy5 Dd0Transformersecondaryvoltage4 )kVDy5 Dd0 (if required +7.5° phase shift)Dy5 Dd0 (if required –7.5 ° phase shift)Transformersecondaryvoltage4 )kVImpulse str. testvoltage:secondarywinding to earth 1 )62.3 800 – 2600 2 x 1.2 2 x 0.6 (2x) – – 23.6 kV3.3 1000 – 4000 2 x 1.7 2 x 0.85 (2x) – – 33.6 kV4.16 1300 – 5000 2 x 2.2 2 x 1.1 (2x) – – 38.9 kV2 x 4.16 4700 – 9100 – – 2 x 2.2 2 x 2.2 (2x) 38.9 kV6.0/6.6 660 – 2000 2 x 1.2 2 x 0.6 (2x) – – 53.0 kVPlease note:Transformers and commutating reactors are notincluded in the converter scope of supply!1) The voltages stated are the necessary test voltages to earth for thetransformer secondary windings. As the transformer windings usuallyincorporate temperature evaluation circuits, test voltages for reinforcedinsulation must be applied. If there are no control circuits in the windings,test voltages for basic insulation are sufficient.2) Please note: Transformers and commutating reactors are not included inthe converter scope of supply!3) Instead of the two three-winding transformers one five-windingtransformer can be used (to be clarified with the transformermanufacturer).4) No-load voltageSiemens DA 63 · 2004 6/17