METHOD AND DEVICE FOR MEASURING HARMONIC CHARACTERISTICS

摘要

PROBLEM TO BE SOLVED: To improve measuring performance by precisely removing the noises of existing order-to-order harmonies in a system from measured values for a voltage and a current of the order-to-order harmonies in the power system during filling. SOLUTION: The noises of the existing filling frequency of the system are found from the digital frequency analysis of a voltage and a current in the power system sampled in synchronization with the system fundamental waves during non-filling at least either before or after filling. The noises are subtracted from the measured values by correcting the phase of the noises during non-filling to the phase during filling or the phase of the measured values during filling to the phase during non-filling. An equivalent circuit constant for the order-to- order harmonies of the filling frequency is calculated by removing the noises from the measured values.