蒸发冷却水轮发电机定子温度场研究

为了提高大型水轮发电机的运行可靠性，设计人员对电机的冷却系统作了不少改进，其中包括线圈采用液态介质内冷系统等。蒸发冷却技术已在中国数个电站的几台立式水轮发电机中得到应用，并经历了长时间的商业运行考验。为了验证这种新型冷却系统的优越性，应对电机内的温度场进行深入的分析。该文以有限元法计算了采用蒸发冷却系统的大型水轮发电机定子三维温度场，以包括导体、端部绕组及通风沟在内的定子半个齿距全轴向长度为计算域，并考虑蒸发冷却的特点，建立了物理和数学模型。论文以李家峡电站一台400MW蒸发冷却发电机为实例，计算了不同工况下的定子温度分布，计算结果与现场实测数据进行分析比较，验证了计算方法的正确性。论文得出了一些有助于设计和运行的结论。

ANALYSIS OF 3D THERMAL FIELD IN THE STATOR OF LARGE HYDRO-GENERATOR WITH EVAPORATION-COOLING SYSTEM

In order to improve the performance reliability of large hydro-generators, the machine designers have made every effort to improve their cooling system, including application of inner liquid cooling system of the coils. Some evaporation-cooled vertical hydro-generators have been installed in power stations of China and put into commercial operation for long time. The identification of advantages of this new cooling system should be based on detailed analysis of the thermal field in electrical machine. A method to calculate 3D thermal field in the stator of large hydro-generators with evaporation cooling system was developed in this paper. The full length with half of tooth and slot, including conductors, end windings and ventilation ducts, was taken as the calculation area. As an example the 3D temperature distributions under different load conditions of the 400MW evaporation cooling hydro-generator at Lijiaxa Power Station were calculated. The precision of proposed method has been proved by comparison of the results calculated and measured at site. Through the work described in this paper some useful conclusions for generator design and operation can be drawn.