The effects of nonlinear loading upon the Space Station Freedom 20 kHz power system

The Space Station Freedom power distribution system, which consists of dual redundant 20 kHz, 440 V RMS, single-phase power systems, is discussed. The effect of a typical space station nonlinear load on the measurement of RMS current and voltage at various points in the Space Station power system has been investigated using the Electromagnetic Transients Program (EMTP). The load current distortion at the user interface, its effect on the distribution system, and its relationship to power factor have been studied. Modeling results are compared to test data. The differences under nonlinear loading are evaluated and presented as a measure of distribution voltage distortion and current measurement accuracy.<<ETX>>