Finite Element Analysis On 3D Eddy Current Field In End Zone Of Large Air-cooled Turbogenerator

In recent years, with the technique of design and manufacture and technological level for air-cooled turbogenerator improved, its technology and economical target also improved. The air-cooled turbogenerator with high reliability, high efficiency and high capacity has gradually been a choice to many generator groups, so the improving of capacity of air-cooled turbogenerator became more and more significant. But the capacity of air-cooled turbogrnerator is improved mainly by adding electromagnetic load of the bar, and loss of the bar will be rasied when adding electromagnetic load, the end region eakage will be enhanced, the eddy current losses of end zone structures will also be increased. The temperature of the generator will increase even above the allowable temperature, and also the reliability of generator be affected. In order to ehance radiating and to reduce losses, the structure of generator must be designed properly. Thus the accuracy of end region field computation of large air-cooled turbogenerator is essential to resolve above issues.Problems in turbogenerator end zone magnetic field were put forward many years ago, but because of the characters of the end zone, it hasn't been settled perfectly. Firstly, against to problems existed in calculation of electromagnetic field in the end region of large air cooled turbogenerator. A full mathematic model used to calculate end field of large turbo-generator by A ,? ?A3D FEM is presented. The model combined end zone with stepped stator core, expanded solved region into the stator and the rotor core. The end structures spatial location, the actual shape of end coil and theirs influence to end field calculation are considered accurately. The stator and rotor coils as well as current carried in coils are included in the model, and simulated accurately. With combined 2D and 3D magnetic field method, the boundary condition is determined. Taking QF-150-2 air-cooled turbogenerator for example, the end field is calculated at no-load and at full load with eddy current taking into account. Then the formula of stator end-leakage reactance is derived, the stator end-leakage reactance is calculated. At last, the parameterization finite element programme of the exciting current parameters is programmed.Then compare the calculation results with the test results, the reliability of the method presented in this paper is verified. It can provide basis for the design of structure of air-...