0000000000149727
AUTHOR
A.e. Emanuel
Current transformers effects on the measurement of harmonic active power in LV and MV networks
The harmonic active power is used to determine the location of polluting loads, the direction of harmonic power flow and to estimate how consequential a certain current harmonic source is. The highest uncertainties, when measuring harmonic active power, are introduced by the current and voltage transducers. This paper presents experimental results which show the impact of current transformers (CTs) on the accuracy of the harmonic power measurements. An expression for the evaluation of the power error in distorted conditions was developed which can be easily utilized in the case of linear current transducers. It is shown how CTs cannot be considered linear transducers and how the higher the …
Characterization and Error Compensation of a Rogowski Coil in the Presence of Harmonics
This paper reports the results of an experimental study dealing with a commercial Rogowski coil current transducer (RCCT) in the presence of harmonic distortion. The RCCT was observed under two conditions: 1) sinusoidal excitation with frequencies from 50 to 750 Hz and 2) nonsinusoidal excitation using fundamental frequency and one harmonic, with adjustable amplitude and phase shift. The experimental results show only a weak dependence of the harmonic current ratio error and phase displacement on the amplitude and phase shift of the excitation harmonic. The phase displacement is also independent of the conductor position within the Rogowski coil window. An error compensation method, based o…
Characterization of clamp-on current transformers under nonsinusoidal conditions
This paper reports the performance of clamp-on current transformers under nonsinusoidal conditions. A set of experimental measurements helped to determine the ratio and the phase errors under two conditions: 1) sinusoidal excitation with frequencies from 45 to 1000 Hz and 2) nonsinusoidal excitation using the fundamental frequency and one harmonic, with adjusted phase shift. It was found that ratio and phase errors are affected by the phase angle between the harmonic and the fundamental and the harmonic amplitude. The effects of conductor location in the current transformer's window and of the air-gap width were also investigated. It was concluded that harmonic phase and ratio errors measur…
Frequency response of Measurement Current Transformers
In this paper the frequency response of two CTs is experimentally evaluated in the range of 30-600 Hz. A theoretical analysis of CTs behavior has been developed by means of the equivalent circuit. It was shown, by an experimental test, that, for the frequency range analyzed, the transformer equivalent circuit is a valid tool for the evaluation of CT performances.
A novel approach to current transformer characterization in the presence of harmonic distortion
The current transformer (CT) performance under distorted waveform conditions is usually characterized by means of the frequency-response test. In this paper, a new way to characterize CTs, closer to real operation conditions, is proposed. The harmonic phase-angle and ratio errors are measured using a nonsinusoidal current composed of fundamental and one harmonic with adjustable phase shift. The new method was tested by determining the performance of two metering class CTs commonly used by the Italian power company. The errors measured using the proposed approach are larger than the ones obtained with the frequency response. This result suggests that the frequency-response approach for the e…
Characterization of Current Transformers in the Presence of Harmonic Distortion
The CTs performance under distorted conditions are usually characterized by means of the frequency response test. In this paper a new way to characterize CTs, closer to real operative conditions, is proposed. The harmonic phase angle and ratio errors are measured when the CTs are excited with a nonsinusoidal current composed of a fundamental and one harmonic, with adjustable phase shift. The errors measured using the new approach were found larger than the ones obtained with the frequency response. This suggests that frequency response is not a reliable method to evaluate the CT performance under distorted conditions.