Damping of Power Swings

This chapter investigates the behavior of relative rotor angle oscillations, which are also known as swings. The damping of these oscillations is a complex function of the operating conditions and system parameters. A major cause of the instability of these oscillations is the action of automatic voltage regulators (AVRs). Power swings are primarily associated with the rotor angle and speed of a synchronous machine. Since feedback controllers like AVRs are necessary for important regulation functions, the damping of the swings may be ensured by adding auxiliary feedback loops which modulate the set‐points of the existing controllers in the system. Such feedback controllers are called power swing damping controllers (PSDCs). The actuators for PSDCs are generally power electronic converters, as they have sufficient bandwidth to affect the swing modes, in addition to having the vernier control capability necessary for modulation. The actuator location has a significant impact on the controllability of swing modes.