A method for identifying the discrete instantaneous angular speed of electromechanical systems in which electrical rotating machinery is used and in which at least one electrical
signal is measured during an operation of the electromechanical
system. The method includes measuring analog
stator current signals and analog
stator voltage signals for at least one phase A, B, C, converting the measurements into a digital
discrete form, transmitting the digital discrete signals to a
computer device wherein
data analysis is performed in a processor unit on the basis of a simplified
mathematical model of the dynamics of the motor or generator. During the
data analysis an average
rotor time constant is calculated, an average supply frequency value is identified, an average angular speed is obtained, and an
instantaneous phase difference between the discrete
stator current signals and the discrete
stator voltage signals is determined. The discrete instantaneous angular speed is identified by combining the average supply frequency value, the
instantaneous phase difference between the discrete stator current signals and the discrete
stator voltage signals, the average
rotor time constant, and a number of pole pairs of the
electric motor, given by the user. The result of combining the data is stored in a memory of the processor unit.