Research on Resistance Enhancement Coefficient and Thermal Dissipation of Stator Strands in Huge Synchronous Generator

Likun Wang,Baoquan Kou,Wei Cai

doi:10.1109/access.2020.2975830

Abstract

For large generators, accurate assessment for the resistance enhancement coefficient (REC) and thermal dissipation is of great significance. With the development of design and manufacturing technology for large generators, the different cross section of the upper and lower strand becomes an effective method to reduce the heat losses. In current electromagnetism design, the eddy current analysis does not take the strand structures into account. In this paper, the REC of strands with special structures of a 150MW turbo-generator is derived by an analytic algorithm. Besides that, a mathematical model of the stator slot is established and the heat losses distribution and REC of strands are calculated by finite element method (FEM). On this basis, the stator REC and thermal dissipation of a 1000MW power turbo-generator are investigated with hollow and solid strands. The calculated results match the experimental data. All of these could provide an important theoretical basis and reference for the design of stator windings in high-power generators.

Highlights

For traditional high-power turbo-generators, double layer windings with lap coils are often adopted for the stators
Researchers have studied eddy current losses and ac resistance for the windings, but few do the research on resistance enhancement coefficient (REC) of strands with special construction and thermal dissipation in large power turbo-generators
ANALYTIC AND NUMERICAL ALGORITHMS FOR REC WITH SPECIAL STRAND CONSTRUCTION Aiming at the different number and cross section area between the upper and lower winding strands, the REC of strands are derived by the following process

Summary

INTRODUCTION

For traditional high-power turbo-generators, double layer windings with lap coils are often adopted for the stators. Researchers have studied eddy current losses and ac resistance for the windings, but few do the research on REC of strands with special construction and thermal dissipation in large power turbo-generators. Eddy current losses of winding strands under rated load operation with special structures, where both the strands number and the cross section area are not the same, are derived by analytic algorithms. ANALYTIC AND NUMERICAL ALGORITHMS FOR REC WITH SAME STRANDS AREA For an AC electrical machine, the stator current and leakage magnetic flux are alternating. B. ANALYTIC AND NUMERICAL ALGORITHMS FOR REC WITH SPECIAL STRAND CONSTRUCTION Aiming at the different number and cross section area between the upper and lower winding strands, the REC of strands are derived by the following process.

Rac Rdc

CONCLUSION