Synchronized Versus Non-Synchronized Feedback for Speed-Based Wide-Area PSS: Effect of Time-Delay

Wide-area power system stabilizers (WAPSSs) based on time-synchronized signals are known to be relatively effective in damping inter-area oscillations. However, the use of wide-area signals introduces time-delay in the feedback loop due to the time taken in fetching the feedback information. In general, delays in the feedback loop are detrimental to the performance of the controller and may lead to instability if the control is not sufficiently robust to tolerate the delay variation. It may be the case that one opts for using non synchronized signals (not time-synchronized) for WAPSS. This paper investigates and compares the effect of delay in synchronized and non-synchronized feedback-based WAPSS. The analysis is carried out using eigenvalue computation for time delay systems and applied to two study systems. It is shown that non-synchronized signals are less sensitive to delay from the systems stability viewpoint even though comparable damping can be achieved.