Justification of some field observations of dynamic load behaviors: Analytical and numerical approach

It is known that modeling impedance in distribution networks, including the percentage of induction motor load, is essential to the study of distribution system dynamic responses. In this paper, some field observations of dynamic load behaviors related to distribution network impedance and the percentage of induction motor load are justified using a novel composite load model and output trajectory sensitivity analysis. To provide this justification, we propose a composite load model named Z-ZIP-IM where equivalent distribution network impedance is serially connected to a conventional ZIP-induction motor (ZIP-IM) model. Then parameter values of the proposed composite load model are estimated using actual measurement data from TVA. Finally, output trajectory sensitivity with respect to model parameters at the obtained values is analyzed. In addition, the numerical identifiability of the obtained parameter values is tested.