Synchronous-machine standstill frequency-response test data analysis

Frequency response methods used in the development of linear transfer functions representing nonlinear processes are extended to standstill frequency response tests for synchronous machines, thus providing an independent check on the equivalent circuit method of IEEE Standard 115A. By iterative subtraction of three separate transfer function elements from the Bode plot of the experimental data an overall transfer function can be synthesized, leaving a small residue of Bode-plotted data that represent irregularities due to nonlinearities, noise, or erroneous data. Suggested limits for the range of test frequencies and the magnitudes of residual transfer function are given