中文摘要：

十二相同步发电机整流系统能够提供高品质直流电能，但是发电机模型复杂，解析分析困难。为此，推导了十二相整流发电机的等效三相降阶模型和状态空间平均模型，简化了模型复杂程度，提高了仿真计算效率。等效三相发电机模型能够同时适用于大、小扰动，经突加突卸负载、调整励磁电压以及突然短路验证，能够正确反应十二相电机运行特性。状态空间平均模型在小扰动时能够准确模拟十二相电机计算结果，进一步提高计算效率，并为整流发电机系统的理论分析奠定了基础。最后，在PSCAD中建立了十二相电机的三相等效模型和平均模型，通过对其进行大、小扰动仿真对比，验证了降阶后模型的正确性。

英文摘要：

The twelve-phase synchronous generator-rectifier system can offer high-quality DC power, but its mathematical model is quite complicated, which makes the analytic computations difficult. To solve this problem, the equivalent three-phase reduced model and the state-space average model are derived to simplify the original model and to promote the computation efficiency. The equivalent three-phase model can be applied under both large and small disturbances, and is validated by simulations on suddenly applying and shedding loads, adjusting of excitation voltage, and short circuit. The state-space average model is applied under small disturbance to make the computation more efficient, and lays the foundation for theoretical analysis of the generator-rectifier system. The equivalent three-phase model and the state-space average model are built in PSCAD. The large and small disturbances on the models are simulated and the results are compared, and the correctness of the simplified models is validated.