Research Of The Electromagnetic Design Process For A Megawatt-class Powerformer

Powerformer is a new type of high voltage generator, which combines modern high voltage cable technique and generator technique. The High-voltage cross-linked polyethylene (XLPE) cables are used as stator windings in Powerformer, and the high voltage can be outputted by the new type structure, which can be connected to the HV network directly. However, Powerformer stator structure lamination is different from classical generator greatly because cables are used as stator winding directly, it is very necessary to research electromagnetic design process for Powerformer systematically. In this paper, determining method of primary dimensions and electrical load of cable windings in the process of Powerformer electromagnetic design are studied in depth.The development background of Powerformer and its research status are introduced firstly, based on which the significance for the study on Powerformer is analyzed.Then, refer to that of traditional generator, the determination method of primary dimensions in design process of Powerformer is researched systematically base on the existing structure of classical generator, in which the mechanical properties and electrical properties of XLPE windings are considered comprehensively. From this study, the determination methods for stator inner and external diameter, pole distance, core length, and frame size are proposed, by using which the dimensions of a megawatt-level Powerformer are calculated.For the stator windings in Powerformer are formed by high-voltage cables directly, the determination for electrical load in traditional generator would not suit for it. After the analysis on the selection of power cable conductor cross section and the calculation of temperature in it, the determine methods for current load and temperature rise for cables windings in Powerformer is proposed, which may improve the calculation accuracy of electrical load in the design process of Powerformer electromagnetic design.Finally, based on the electromagnetism design process of traditional generator, using the methods proposed in this paper for determinations for primary dimensions and electrical load, the electromagnetic design of a megawatt-level Powerformer is carried out.The obtained conclusion could supply of reference to the reasonable and reliable design for Powerformer, and has certain significance both in theoretical and practical issues.