带径向通风沟的大型水轮发电机励磁电流计算

Calculation of Excitation Current of Large Hydro Generator with Radial Ventilation Ducts

励磁电流是大型水轮发电机设计的一个重要参数,直接影响电机的效率、温升等。但受径向通风沟和端部效应的影响,电机铁芯本体磁场沿轴向的分布并不一致。在电机磁路计算时,每一段磁路采用相应的轴向有效长度,很明显该方法并不适用于励磁电流的二维有限元计算。因此,本文提出了电机等效长度计算方法和硅钢片导磁特性等效方法,并将其用于励磁电流的二维有限元计算中。以一台在电站实际运行的真机为例,利用本文提出的方法对其空载和负载励磁电流进行了计算,并与实测结果进行了对比,证明了方法的准确性。

Excitation current is an important parameter in the design of large hydro generator, which directly affects the efficiency and temperature rise of the generator. However, due to the influence of radial ventilation duct and end effect, the distribution of the magnetic field of the core along the axial direction is not consistent. In the magnetic circuit calculation of electromagnetic design, each magnetic circuit adopts the corresponding axial effective length. Obviously, this method is not suitable for the calculation of excitation current using 2D FEM. Therefore, the calculation method of the equivalent length and the magnetic conductivity equivalent method of silicon steel are proposed in this paper, which are used in the 2D finite element calculation of excitation current. Taking a hydro-generator running in the power station as an example, the no-load and load excitation currents are calculated by the method proposed in this paper, and compared with the measured results to prove the accuracy of the method.