Dynamic on-line measurement of equivalent parameters of three-phase systems for harmonic frequencies

A method of an on-line measurement of equivalent parameters for harmonic frequencies of a three-phase distribution system with harmonic generating loads is discussed in the paper. The impedances of the supply and the load, the complex RMS (CRMS) values of the load generated current harmonics, and the CRMS values of the distribution voltage harmonics are the subject of the measurement. It is shown that the on-line measurement of these parameters requires that the line voltages and currents are measured at least in three different states of the system. These states of the tested system are changed by disturbing the system with a current harmonics generating device, built in a form of a fast thyristor switch. The method is illustrated with measurements in a physical system