Frequency Characteristics of Current Transducers in 0-100 kHz

článek ve sborníku ve WoS nebo Scopus

angličtina

AC current in power systems is usually measured by current transducers (CT) (i.e. by instrument current transformers (ICT) or in some minority cases by Rogowski coils (RC)). Both mentioned CT are primarily designed to correctly measure current of the nominal frequency. However, when CT are installed in real power networks, the measured current on the primary side of the CT may be composed of many harmonic and inter-harmonic components and it can also have a DC component. It has been investigated in recent papers that in case of voltage transformers (VT) the presence of components with higher frequency in measured signal may cause serial/parallel resonances of internal circuit elements of VT. These resonances may be the source of distortion of the measured quantity (voltage) on the secondary side of the VT and the voltage readings from such an instrument may be flawed by additional error. The similar effect of resonances can be expected in case of CT, however CTs have not been investigated properly yet. Thus, in this paper the measuring error of CT is investigated when used for measuring currents composed of components with higher frequencies. The possible error is evaluated on the difference between reference measurement of the generated signal on the primary winding by instruments with high precision and compared with readings obtained from the secondary winding of CT. For the evaluation of CT response to currents of higher frequencies, three cases are considered – transfer of signal composed of nominal and higher frequency component, transfer only of signal of higher frequency, and the response to higher frequency component with DC component. The possible error in magnitude and phase measurement for all aforementioned cases is then evaluated (i.e. the transfer of nominal frequency component, the transfer of higher frequency component, and also the influence caused by the presence of DC component in measured signal. The higher frequency current component is generated with frequency ranging up to 100 kHz. The CT measured for the purpose of this paper were both ICT and Rogowski coil. Also, different burdens of ICT secondary were examined.

frequency chracteristics; current transducer; instrument transformer; Rogowski coil; power system measurement; current transformer

VYČÍTAL, V.; DRÁPELA, J.; TOMAN, P.; TOPOLÁNEK, D.

24. 9. 2018

ADEERA

Buenos Aires, Argentina

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