Finite Element Modeling of Large Turbine Generators; Calculations Versus Load Test Data

In support of EPRI Program 1288-1, Improvement in Accuracy of Prediction of Electrical Machine Constants, generator parameters at load have been calculated by the finite element method, in two dimensions. These calculated parameters are compared with test data obtained under EPRI Program RP 997-2, Determination of Synchronous Machine Stability Study Constants. An iterative procedure was used to match the calculated terminal voltage with the test value, for a given armature current and power factor. The test/calculated values for field current, the various angles, and Xq are then compared. Good agreement in all the above parameters is obtained for six diverse load points. Reactances are also compared. Considerable saturation effect is found, and is confirmed by test data in the case of X4. The results of this systematic comparison are judged to be a confirmation of the power of the finite element method.