Online Oscillation Detection based on PMU-Data in the Control System

In this paper, we introduce an online oscillation detection tool based on Phasor Measurement

Unit (PMU) data embedded into a modular control system environment allowing for real-time estimation of power system oscillatory modes during operation and further processing of information within the control system. This enhances the monitoring and assistance functionalities of modern control systems enabling the operator to act immediately on critical situations, thus directly addressing the topic “Monitoring and control of power system dynamics in the control room, including wide area systems” of C2 PS3.

The modular architecture of the control system is presented and the data stream from field measurements to the final visualization of mode estimation results within the control system is illustrated. Moreover, the architecture and workwise of the oscillation detection tool is elaborated. We identified two mode estimation methods based on ambient power system measurements as particularly suitable, the (modified extended) Yule-Walker [4] and the

Kalman filter method [5]. For mode shape estimation we make use of an approach based on the power spectrum of the signals [6]. All applied methods are briefly described, before an extensive investigation of the oscillation detection tool within the control system environment is presented. We perform some benchmark tests with anonymous PMU-data from the

Hungarian and Czech transmission systems and compare the results with the ones obtained by

WAMtool [7]. We find that the results are in good agreement. Moreover, computational times from online application of the developed oscillation detection within the control system environment indicate that the tool is suitable for real-time application during operation. We conclude the paper with an extensive discussion and outlook, stressing the need to combine conventional control system functionalities with PMU-data based tools. This will enhance not only the monitoring capabilities but also allow for, e.g., countermeasure validation due to the availability of grid topology, models and parameters within the control system itself.