Power System Monitoring and Control

3Small-Signal Stability Assessment

Power system stability can be affected by many factors, such as the growth of demand, the use of more large-capacity generators installed at remote locations from the demand center, longer transmission lines, the heavier power flow on tie-lines, especially the penetration of renewable energy sources with large power fluctuations, and so on. The risk of synchronous generator outage or a wide-area power blackout should be reduced even in such severe conditions. The techniques of monitoring and estimation of power system stability are key issues to prevent power outages.

In recent years, various methods of online monitoring have been proposed [1–6]. These methods place emphasis on the adaptive wide-area control to address complicated system state changes. For this purpose, in order to grasp the behavior of the whole power system in real time, wide-area data acquisition is required. To implement such real-time monitoring and control based on wide-area data acquisition, some parameters such as phase angle, bus voltage, frequency, and line power flow at multiple sites should be measured simultaneously.

This chapter introduces basic concepts of the power system small-signal stability assessment. As described in Chapter 2, interarea low-frequency oscillations can be considered as characteristic phenomena in large-scale interconnected power systems. The electromechanical dynamics of interarea oscillations with poor damping characteristics in an interconnected ...