Estimating Speed of Frequency Disturbance Propagation Through Transmission and Distribution Systems

Changes in power system operating conditions cause dynamic changes in angle and frequency. These changes propagate through the system as disturbances in frequency as previously studied (J.S. Thorp, et al., 1998), (L. Huang, et al., 2001). The disturbances in system frequency travel with finite speed across the system area (M. Parashar, et al., 2004). Thus a sudden loss of generation or load in one area would be seen as a frequency disturbance in other areas of the power system. Through use of wide-area frequency measurements these traveling frequency disturbances can be observed and recorded to be used for real time system analysis. Currently the majority of wide area measurements are taken by PMUs and similar devices at the transmission level. This paper focuses on the effects of performing these measurements at the distribution level and how this additional layer of the system can affect the measurements. It is important to note that the relevant effects of machine inertia are not considered in this study. Rather this paper focuses on system/line impedance in the determination of electromechanical wave propagation speed