Inter-Area Oscillation Damping With Non-Synchronized Wide-Area Power System Stabilizer

One of the major issues in an interconnected power system is the low damping of inter-area oscillations which significantly reduces the power transfer capability. Advances in Wide-Area Measurement System (WAMS) makes it possible to use the information from geographical distant location to improve power system dynamics and performances. A speed deviation based Wide-Area Power System Stabilizer (WAPSS) is known to be effective in damping inter-area modes. However, the involvement of wide-area signals gives rise to the problem of time-delay, which may degrade the system performance. In general, time-stamped synchronized signals from Phasor Data Concentrator (PDC) are used for WAPSS, in which delays are introduced in both local and remote signals. One can opt for a feedback of remote signal only from PDC and uses the local signal as it is available, without time synchronization. This paper utilizes configurations of time-matched synchronized and nonsychronized feedback and provides the guidelines to design the controller. The controllers are synthesized using $H_\infty$ control with regional pole placement for ensuring adequate dynamic performance. To show the effectiveness of the proposed approach, two power system models have been used for the simulations. It is shown that the controllers designed based on the nonsynchronized signals are more robust to time time delay variations than the controllers using synchronized signal.