2013. — 8 c.Wide-area monitoring systems (WAMS) offer the possibility of supervision of power system dynamic phenomena. They are based on phasor measurement units, which are most often synchronized using a global positioning system (GPS) clock to provide time-synchronized voltage and current phasor, as well as frequency measurements with synchronization accuracy better than microseconds.
This paper describes a new damping estimation application that employs WAMS data to estimate the damping of oscillatory modes from ambient data before a disturbance [5-7]. This can give an indication of the damping of transient oscillations that will follow a disturbance, once it occurs. The application is based on a system identification procedure that is carried out in real-time using a sliding measurement window. If the transfer between two grid areas is limited by inadequate damping, the damping monitor can assist in maximizing the power transfer capability by providing a faster and more accurate view of the current situation than one obtained via off-line dynamic simulations. This is possible since the PMU measurements are not subject to modeling errors that are potentially present in the off-line simulation models. Such modeling errors could lead to definition of overly conservative or even inadequate transfer limits. The new damping monitoring application also identifies the parts of the power system that participate in a detected oscillation through modal activity information that can be used to determine the root cause of a poorly damped oscillatory mode, and serve as starting point for the definition of improvement measures.
Furthermore, any fast power electronic devices able to directly or indirectly modulate electric power flows (such as FACTS, HVDC or the excitation systems of synchronous generators), can be used as actuators to improve poor damping, provided they are equipped with appropriate controller extensions.
