Development of a High-Performance Induction Generator for Wind Power and Small-Scale Hydropower Plants

最近，风力发电和小规模水力发电作为有助于环境保护的可再生能源已被广泛采用。在这样的发电厂中，感应发电机被广泛使用，因为它们可以直接连接到电网，并且不需要太多的附加设备，同时在成本和维护方面是有利的。然而，感应发电机需要来自电网的磁化电流，这基本上导致功率因数和效率的降低。因此，感应发电机的性能需要进一步提高。在本研究项目中，开发了一种新型的感应发电机，称为“永磁感应发电机（PMIG）”。PMIG有一个自由旋转的永磁转子（PM转子），安装在与轴相连的鼠笼转子内。定子与普通感应发电机的定子相同。设计并制造了一台2.2 kW的样机。为了建立一个指导方针，创造一个最佳设计的PMIG，稳态分析的技术也被开发。在样机上进行的实验验证了所开发技术的有效性和PMIG的实用价值。结果发现，由PM转子产生的内部自励磁有助于减少磁化电流，并提高功率因数和效率。

Recently, wind power and small-scale hydropower have been extensively introduced as renewable energy sources that contribute to environmental protection. In such power plants, induction generators are widely used because they can be directly connected to a power grid and do not require much additional equipment while being advantageous in terms of cost and maintenance. However, the induction generators require a magnetizing current from the power grid, which essentially causes a decrease in power factor and efficiency. Therefore, the performance of the induction generators needs further improvement.In this research project, a new type of induction generator termed the "Permanent-Magnet Induction Generator (PMIG)" was developed. The PMIG has a permanent magnet rotor (PM rotor) rotating freely that is mounted within a squirrel-cage rotor linked to the shaft. The stator is the same as that of usual induction generators. A 2.2-kW prototype machine was designed and built. To construct a guideline for creating an optimum design of the PMIG, a technique for the steady-state analysis was also developed. The validity of the developed technique and the practical value of the PMIG were confirmed through experiments performed on the prototype machine. As a result, it was found that the internal self-excitation by the PM rotor contributes to a decrease in the magnetizing current and improves the power factor and efficiency.