Monitoring and Control of Power System Oscillations using FACTS/HVDC and Wide-area Phasor Measurements

摘要

Power oscillations are a growing concern among power system operators worldwide. Traditionally, themain countermeasure against dangerous power oscillations has been the installation of power systemstabilizers (PSS). Essentially, the potential for inter-area power oscillations depends on the strength ofthe tie lines between different areas and the load on the ties. From a European perspective, with theanticipated integration of remote renewable energy sources such as offshore wind power from theNorth-sea region and solar power from southern Europe or Africa, we can expect the averagetransmission distances to grow and consequently also tie line flows. Unless tie lines are also reinforcedwe expect more oscillation events in the European grid in the future.From an operational point of view, it is of high priority to be able to estimate the damping ofoscillatory modes reliably in real-time in order to take appropriate and timely measures in casedamping becomes poor. Recent developments in wide-area phasor monitoring have resulted in a newpower oscillation monitoring algorithm that uses multiple measurements from different locations inthe grid. An equivalent system model of the power grid is estimated in real-time and based on thismodel, the damping and frequency as well the activity of oscillatory modes can be determined fromambient process variations. As basis for this, a wide-area measurement system (WAMS) can providetime synchronized signals from phasor measurement units (PMUs) that can measure voltage, currentand frequency with adequate accuracy and resolution in time. This paper shows results from pilotoperation of the new application at swissgrid, including recordings from an actual and representativeevent in the continental ENTSO-E interconnected power system. This example demonstrates theperformance of the new application as well as provides information about the oscillatory modespresent in the continental ENTSO-E system today.Furthermore, FACTS and HVDC systems can serve as powerful actuators to control inter-areaoscillations, provided they are equipped with appropriate controller extensions. Particularly for thecontrol and management of inter-area oscillations, remote measurements have proven useful. Thepaper outlines the technical aspects and suggests a design procedure for controller extensions based onlocal or remote measurement for the purpose of inter-area oscillation damping.