Influence of total flow rate on complex fluid flow and temperature rise in the rotor region of large Hydrogenerators

摘要

Water is a renewable clean energy, which is an important resource for power generation. Hydropower development depends largely on the development of hydrogenerator. The performance of a large hydrogenerator is largely influenced by temperature rise, so the design of the ventilation cooling system in the large hydrogenerator has become one of the key factors during the design process of large hydrogenerators. As the capacity of large hydrogenerator increases, the heat load and the electromagnetic load which would affect the operating life of hydrogenerators also increase. The heat problem in the hydrogenerator becomes more and more serious. The traditional analytical method for solving the temperature rise of hydrogenerator parts cannot accurately simulate the temperature distribution of hydrogenerator parts, which results in a large deviation to the calculation. Therefore, it is urgent to adopt a novel numerical calculation method to study the heating of the hydrogenerator. The novel numerical calculation method for complex fluid flow and part temperature in the rotor region of a large hydrogenerator is proposed in this study. Two-dimensional mathematical and physical models of the transient electromagnetic field are given by studying a large hydrogenerator for an example in this paper. Two-dimensional transient electromagnetic field equations of the hydrogenerator are solved using the finite element method. The distribution of the electromagnetic field and the losses of the parts in the hydrogenerator are obtained. According to the complex structure characteristics of a large hydrogenerator, taking the effect of rotor rotation into consideration, mathematical and physical models of three-dimensional fluid and thermal coupling of the hydrogenerator rotor region are established. The losses obtained from the transient electromagnetic field calculation are applied to the hydrogenerator parts as heat sources in the fluid and thermal coupling field. Using the finite volume method, the change laws of fluid velocity between the rotor poles of the hydrogenerator are gained at different total flow rates. With the change of total flow rate, the temperature change laws of rotor exciting winding, press plate, rotor damper winding, and rotor end ring are determined. The temperature distribution of rotor exciting winding is studied at different total flow rates. The calculated results match well with measured data.