Determination of electromechanical eigenvalues based on analysis of different disturbance waveforms of a power system

The paper presents the calculation results of the power system state matrix eigenvalues associated with electromechanical phenomena (i.e. electromechanical eigenvalues). There is compared the accuracy of eigenvalue calculations performed on the basis of the analysis of disturbance waveforms of instantaneous power, angular speed and power angle of generators of particular generating units of the power system. The method used for eigenvalue calculations consists in approximation of the disturbance waveforms of generating units with waveforms being a superposition of modal components whose parameters depend on the searched eigenvalues and their participation factors. A hybrid optimisation algorithm, being a serial combination of genetic and gradient algorithms, is used for minimisation of the objective function defined as a mean square error between the approximated and approximating waveforms. In order to increase the calculation accuracy, computations were repeated many times. The computation results were averaged.