【目的】世界上单机容量最大的1 750 MW核电机组采用的46相无刷励磁机与常见奇数相机型有较大区别。目前，对于超大容量、偶数相无刷励磁机的研究仍相对滞后，处于励磁系统保护中的薄弱环节，迫切需要对46相励磁机进行正常和故障等多种工况的运行机理进行分析，为后续故障保护提供依据。因此，本文提出一种基于偶数相环形无刷励磁机的电枢绕组并联等值模型的分析方法。【方法】首先对46相无刷励磁机电枢绕组的实际结构进行详细分析，进而得出二极管电流、电枢电流和励磁电流的理论波形。然后，根据电枢反应磁势得出正常运行、单管开路、一相开路和两相开路时定子励磁电流的谐波特性。最后，通过仿真与现场试验对比验证所提分析方法的性能。【结果】46相实际机组的真机试验和有限元仿真结果，验证了电枢绕组并联等值模型与多种工况下定子励磁电流谐波特性的正确性。【结论】本文揭示了偶数相环形无刷励磁系统的运行特性以及不同类型二极管开路的故障特征，为进一步研究大容量核电站多相无刷励磁系统的故障诊断提供了参考。

[Objective] The 46 phase brushless exciter used in the 1 750 MW nuclear power unit, which has the largest single unit capacity in the world, is significantly different from the common odd numbered camera types. Currently, research on ultra large capacity and even-phase brushless exciters is still relatively lagging behind, and there is an urgent need to analyze the operating mechanism of the 46 phase exciter under various working conditions, including normal and fault conditions, in order to provide a basis for subsequent fault protection. Thus, this paper proposes an analysis method for the parallel equivalent model of armature winding based on even-phase toroidal brushless excitation machine. [Methods] Firstly, the actual structure of the armature winding of the 46 phase brushless excitation machine was analyzed in detail, and then the theoretical waveforms of diode current, armature current, and excitation current were obtained. Then, based on the armature reaction magnetic potential, the harmonic characteristics of the stator excitation current during normal operation, single-diode open circuit, single-phase open circuit, and two-phase open circuit were obtained. Finally, the performance of the proposed analytical method was validated by establishing a finite element simulation model consistent with the actual physical machine. [Results] The correctness of the armature winding parallel equivalent model and the harmonic characteristics of stator excitation current under various operating conditions were verified based on the real machine experiments and finite element simulation results of the 46 phase actual unit. [Conclusion] This paper investigates the operational characteristics of even-phase annular brushless excitation systems and the fault signatures associated with various diode open-circuit failures. The study provides a reference for further research on fault diagnosis in high-capacity nuclear power plants multi-phase brushless excitation systems.

台山核电合营有限公司资助项目(E23GY00100)