Study on Capacitive Leakage Error of Current Transformer in Distribution Network: Theory and Testing

Xiong, Kui; Yue, Changxi; Yu, Jicheng; He, Li; Zhu, Kai

doi:10.1109/ispec48194.2019.8974986

Cited by 2 publications

(2 citation statements)

References 4 publications

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“…The construction-related current errors associated with ferromagnetic parameters, leakage inductance, secondary-side impedance requirements, and stray capacitance between turns are widely known and analyzed in detail [ 11 , 13 , 14 ]. On the other hand, the stray inter-winding capacitances and their limiting effects on CT’s operation are rarely analyzed in detail [ 15 , 16 , 17 , 18 , 19 , 20 ]. In particular, no details on the control design of the assisting electronic unit, its tuning recommendations or both are provided.…”

Section: Introductionmentioning

confidence: 99%

Current Ratio and Stability Issues of Electronically Enhanced Current Transformer Stimulated by Stray Inter-Winding Capacitance and Secondary-Side Disturbance Voltage

Zajec

2022

Sensors

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Electronically enhanced current transformers (EECT) have gained much interest in power quality assessment. Their magnitude and phase angle error, which mainly relates to the properties of the ferromagnetic materials used, the impedance of the secondary load, and the inter-turns capacitance, are thoroughly analyzed. In contrast, the capacitance between the windings, i.e., inter-winding capacitances and their limiting effects on EECT operation, are rarely analyzed in detail—in particular, no details on the control design of the assisting electronic unit, its tuning recommendations, or both are provided. In this paper, the capacitive coupling between indication and compensating winding of EECT with simplified feedthrough construction is analyzed thoroughly in terms of current ratio error and stability of the implemented configuration of the trans-conductance amplifier. The preliminary assumption about the adverse effect of the inter-winding capacitance shunting both ends of the original amplifier, composed of two series-connected inverting amplifier stages, was confirmed and resolved within a modified amplifier with the help of a simplified simulation model and was experimentally proven with measurements on a custom-built EECT prototype. Furthermore, the analyzed phenomena were linked to trans-conductance amplifier parameters, explicitly with its compensating networks, and summarized in their design guidelines. Throughout the paper, the EECT features obtained with original and modified amplifier designs are compared with the plain composite current transformer to demonstrate the benefits of the modified amplifier, especially its robustness against inter-winding capacitance variations.

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Section: Introductionmentioning

confidence: 99%

Current Ratio and Stability Issues of Electronically Enhanced Current Transformer Stimulated by Stray Inter-Winding Capacitance and Secondary-Side Disturbance Voltage

Zajec

2022

Sensors

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“…The leakage current measurement method described in [17] is further improved by measuring the fundamental component rather than the root-mean-square current [24] and by measuring the phase between primary current and leakage current as well [25]. Both improvements were compared to the conventional comparison method of simultaneously applying current and high potential, though the reference CT ratios were still assumed to have negligible voltage dependency.…”

Section: Introductionmentioning

confidence: 99%

Voltage Dependence of the Reference System in Medium- and High-Voltage Current Transformer Calibrations

Brom

Leeuwen

Rietveld

et al. 2021

IEEE Trans. Instrum. Meas.

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A sampling current ratio measurement system has been developed to calibrate the voltage dependence of the ratio error and phase displacement of current transformers (CTs) used for medium-voltage (MV) and high-voltage (HV) applications. The influence of the voltage-induced leakage current on the apparent ratio error and phase displacement of the reference circuit was unambiguously demonstrated using a novel measurement method. Measurement results for voltages up to 24 kV show that the observed leakage current is purely capacitive and caused by the shielded cable capacitance of the HV cable used to feed the current. The maximum ratio error and phase displacement were found to be about 100 parts in 10 6 and 100 μrad for the smallest current of 100 A used for these investigations. Since these values scale linearly with the applied voltage and inversely proportional with current, the assumption of negligible voltage dependence used in other reference systems presented in literature is questionable. Using the corrected reference circuit, a commercial class 0,2S MV CT with 2500 A nominal current was calibrated at voltage levels up to 24 kV. The voltage dependence of the ratio error and phase displacement for primary currents up to 500 A was demonstrated to be capacitive as well, with a maximum impact on the current ratio of almost 0.9 % for a primary current of 100 A (corresponding to 3.6 % at 1 % of nominal current). This value is beyond the limits of in-force standards, which emphasizes the necessity of implementing voltage dependence testing in those standards.

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Study on Capacitive Leakage Error of Current Transformer in Distribution Network: Theory and Testing

Cited by 2 publications

References 4 publications

Current Ratio and Stability Issues of Electronically Enhanced Current Transformer Stimulated by Stray Inter-Winding Capacitance and Secondary-Side Disturbance Voltage

Current Ratio and Stability Issues of Electronically Enhanced Current Transformer Stimulated by Stray Inter-Winding Capacitance and Secondary-Side Disturbance Voltage

Voltage Dependence of the Reference System in Medium- and High-Voltage Current Transformer Calibrations

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