Insulation Structure Design Of High-voltage Generator Stator Bar And Study On Its Properties

Generator with larger unit capacity has better economical performance, but it takes lots of unfavorable factors to the stability of generator insulation system. The rated voltage 24kV²7kV of 1000MW generator machine is the study hotspots of the domestic generator manufacturers. By now, the biggest generator machine is the machine for the three gorges project with the unit capacity of 700MW and rated voltage of 20kV. The bottleneck to manufacture 1000MW generator rests with the insulation system, especially the stator bar insulation system.The dissertation centred on two main research topics, the investigation on insulation materials and the design of the insulation structure of the stator bar. The properties of the straight bar and experimental stator bar as designed were evaluated by dielectric dissipation factor, dielectrical strength, partial diacharge, electric aging test and thermal stability test. As the result, experimental stator bars with excellent properties were obtained.Following results can be concluded. (1) The grouding insulation thickness of stator bars of 24kV and 27kV can be reduced to 5.25mm and 6.20mm, respectively. Such results meet the requirements of insulation design. (2) Thanks to the investigation of insulation materials, the slot-fill rates of 24kV and 27kV Robel bar were increased by 15.4% and 14.8% respectively. (3) The electrical field of stator bar distributes more uniformly with the structure design of the inner anticorona layer when the radius of the bar corner is 2mm and the semiconductive polyester resin was used. (4) In the structure design of internal shielded layer, the electrical properties of the stator bar can be improved when the internal shield layers of 24kV and 27kV stator bar were wrapped in the thickness direction of d₁=1.51mm and d₁=1.71mm, respectively and the length end of the layer is in the middle point of the high-resistance tape end and the leading of stator bar. (5) The electrical properties of the experimental stator bar meet the demand of 1000MW generator insulation system design.