Sharif Digital Repository

Utility harmonic impedance estimation is an important stage for the study and control of electrical networks power quality such as harmonic sharing determination between a utility and a customer at a point of common coupling (PCC). In this estimation, non-invasive methods, as compared with invasive methods, are more desirable since they do not need to apply intentional disturbances to the power network and can work based on natural load fluctuations. The only concern about such methods is the method accuracy. These methods require simultaneous and synchronous measurements of the voltage and current at the PCC. However, one of the causes of error in the utility harmonic impedance measurement... 

L-Ascorbate anion electro-oxidation on a silver electrode in hydroxide solution in the absence and presence of sodium polysulfide of concentrations from 1 × 10 -5 to 4.5 × 10 -4 mol/L was studied using cyclic voltammetry and electrochemical impedance spectroscopy. Both hydroxide and polysulfide ions inhibited L-ascorbate ion oxidation, with the poisoning effect of polysulfide ion being more pronounced in the potential range of -0.3 to -0.2 V/SCE. The time constants for L-ascorbate ion oxidation in the absence and presence of polysulfide were, 10 -3 to 1 × 10 -2 s and 1 × 10 -4 to 1 × 10 -2 s, respectively depending on the potential used for the impedance analysis. Based on the cyclic...