Using spectral analysis and modal estimation for identifying electromechanical oscillations: A case study of the power system in northern Norway and northern Finland

This paper analyses electromechanical oscillations in the northern area of the Nordic power system. Both spectral analysis and modal identification methods are used to analyze signals received from the phasor measurement units (PMU) installed in the system. Spectrograms are used to analyze the characteristics of electromechanical oscillations and to support the interpretation of the modal identification methods. The results indicate that these methods are effective in presenting the oscillatory characteristics of the system. In addition, the results show that the spectrograms help in interpretation of the modal estimates.