Analysis of dynamic systems is often carried out at steady state condition. For cyclic systems like rotating machinery, it is not possible to detect this condition by simply monitoring the change rate of their variables, due to their periodicity. This paper focuses on methods for stationary periodic steady state identification of AC electrical systems. An overview of relevant methods is given and mappings of periodic variables to equivalent stationary variables are discussed. Two new periodic steady state monitors based on Short Time Fourier Transformation are proposed. The study was motivated by the need to identify the steady state condition of an aircraft electrical network for power quality checks. An implementation with Modelica tools is demonstrated.
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