Impact of internal power factor angle on thermal response of stator winding insulation in synchronous generators

The power factor in electric power systems change frequently due to increases in load demand. Consequently, the internal power factor angle (IPFA) of synchronous generators vary under different operating conditions. Accurately understanding the performance of synchronous generators under various IPFAs is of great significance for ensuring the stable and efficient operation of power systems. This paper presents the first investigation of the thermal responses of the stator winding insulation in synchronous generators under different IPFAs. The impacts of the IPFA on the magnetic flux density (MFD), stator current, and losses are comprehensively studied. Unlike other research, this article takes into account the interactions between core—loss—induced heat and copper—loss—induced heat. In addition, it delves into the impact of the IPFA on thermal degradation distribution patterns. Based on the electromagnetic—thermal—structure coupling calculation, the critical points in winding insulation are identified by the distribution of thermal responses under varied IPFAs. Finally, experiments are conducted on a 5 kW prototype generator to verify the accuracy of theoretical analysis and FEA calculation.

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Cite this article

[IEEE Style]

Y. He, J. Yang, K. Sun, W. Wang, X. Zhu, S. Wan, F. Zhang, D. Gerada, "Impact of internal power factor angle on thermal response of stator winding insulation in synchronous generators," Journal of Power Electronics, vol. 26, no. 2, pp. 420-432, 2026. DOI: 10.1007/s43236-025-01073-7.

[ACM Style]

Yu-ling He, Jia-wen Yang, Kai Sun, Wen Wang, Xiaoguang Zhu, Shu-ting Wan, Fengyu Zhang, and David Gerada. 2026. Impact of internal power factor angle on thermal response of stator winding insulation in synchronous generators. Journal of Power Electronics, 26, 2, (2026), 420-432. DOI: 10.1007/s43236-025-01073-7.