Standardized Electrical Power Quality Analysis in Accordance with MIL-STD-704 2010-01-1755
MIL-STD-704 defines power quality in terms of transient, steady-state, and frequency-domain metrics that are applicable throughout a military aircraft electric power system. Maintaining power quality in more electric aircraft power systems has become more challenging in recent years due to the increase in load dynamics and power levels in addition to stricter requirements of power system characteristics during a variety of operating conditions. Further, power quality is often difficult to assess directly during experiments and aircraft operation or during data post-processing for the integrated electric power system (including sources, distribution, and loads). While MIL-STD-704 provides guidelines for compliance testing of electric load equipment, it does not provide any instruction on how to assess the power quality of power sources or the integrated power system itself, except the fact that power quality must be satisfied throughout all considered operating conditions. Thus, the standard leaves much room for interpretation while significantly different results can be obtained by adjusting the framework parameters of the power quality analysis. This paper addresses power quality analysis and its ramifications during post-processing of simulation, experiment, and prototype aircraft data. It provides methods to evaluate transient, steady-state, and frequency metrics defined in MIL-STD-704 in addition to several data visualization techniques, in particularly for the distortion spectrum analysis. Further, appropriate data acquisition rates for the analysis of the individual metrics are addressed. The discussion culminates in several recommendations for the analysis of transient and frequency-domain specifications in terms of framework parameters and methods. These recommendations, in one form or the other, are an attempt to amend MIL-STD-704 and further standardize power quality analysis. Finally, a Matlab toolbox is introduced that allows the automated power quality analysis of experimental or simulation data based on the techniques discussed in this paper.