Defence of dissertation in the field of Electrical Engineering, M.Sc. (Tech.) Janne Seppänen
The title of thesis is “Methods for Monitoring Electromechanical Oscillations in Power Systems”
Electromechanical oscillations are an inherent property of power systems and the damping of the oscillations is the limiting factor for the transmission capacity of certain transmission corridors. In the most severe situations, unstable oscillations may lead to blackouts or even to the collapse of the entire system. Therefore, it is important to monitor the characteristics of the oscillations.
The oscillations can be monitored by using phasor measurement units (PMU). The development of wide area monitoring systems (WAMS) consisting of several PMUs has enabled the use of multiple synchronized measurements received from several locations in the power system to be used for the monitoring of the oscillations.
The thesis presents four new methods for the monitoring of electromechanical oscillatory modes. The methods utilize WAMS measurements for the identification of the modes and are able to continuously identify electromechanical modes from ambient oscillations, which are mainly excited by load variations and are constantly present in power systems. The thesis also illustrates additional analysis tools that can be used to support the modal identification in real power systems.
The thesis shows that the proposed methods are functional for the monitoring of electromechanical oscillations. The thesis also highlights the need of using additional tools, such as spectral analyses, which may significantly help the interpretation of modal identification results. Transmission system operators can use the methods presented in this thesis as building blocks to create applications for the monitoring of electromechanical modes. Consequently, the information given by the methods can be used to improve the security and reliability of power systems.
Opponents: Assistant Professor Herwig Renner, Graz University, Austria and Professor Christian Rehtanz, Technical University of Dortmund, Germany
Supervisor: Professor Matti Lehtonen, Aalto University School of Electrical Engineering, Department of Electrical Engineering and Automation.
Janne Seppänen, +358 40 662 0865, email@example.com