scholarly journals Nonlinearity of Magnetic Core in Evaluation of Current and Phase Errors of Transformation of Higher Harmonics of Distorted Current by Inductive Current Transformers

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 118885-118898
Author(s):  
Michal Kaczmarek ◽  
Ernest Stano
Keyword(s):  
Magnetic Core ◽  
Current Transformers ◽  
Higher Harmonics ◽  
Phase Errors

scholarly journals Formation of Orthogonal Components of Input Currents in Microprocessor Protections of Electrical Equipment

2021 ◽  
Vol 64 (3) ◽  
pp. 191-201
Author(s):  
F. A. Romaniuk ◽  
Yu. V. Rumiantsev ◽  
V. Yu. Rumiantsev ◽  
I. V. Novash
Keyword(s):  
Dynamic Properties ◽  
Electrical Equipment ◽  
Magnetic Core ◽  
Degree Of Saturation ◽  
Current Transformers ◽  
Input Action ◽  
Magnetic Cores ◽  
Orthogonal Components ◽  
Aperiodic Component ◽  
Microprocessor Protection

The methods used in the microprocessor protection of electrical equipment for forming orthogonal components of input currents ensure their reliable isolation after changing the mode followed by one or more periods of the fundamental frequency. This is due to the inertia of the functional elements, in particular, digital frequency filters, as well as the saturation of the steel magnetic cores of current transformers. To increase the speed of the selection of orthogonal components of the input currents, it is proposed to form them as equivalent ones in terms of the cosine and sine components obtained using digital Fourier filters by multiplying by the resulting coefficient. The method that has been developed for determining the specified coefficient provides compensation for the delay caused by the inertia of digital filters, as well as the saturation of the steel of magnetic cores of current transformers. The proposed method of forming orthogonal components is highly effective in the modes of strong saturation of the magnetic core with a complex input action in the presence of an aperiodic component with a large damping time constant. The evaluation of the efficiency of the proposed method was performed using a complex digital model implemented in the dynamic modeling environment MatLab-Simulink. As a result of the performed studies, it was found that in the absence of saturation of the magnetic core of current transformers, as well as in the presence of a small and medium degree of saturation, the proposed method for forming equivalent orthogonal components of input currents has dynamic properties close to the ones of those that had been previously proposed. With a strong saturation of the magnetic core of current transformers, the speed of obtaining reliable values of these components is increased by 1.5–2 times.

The Fault Signal Extraction Research in the Electric Power Metering System

2015 ◽  
Vol 743 ◽  
pp. 555-559
Author(s):  
J.J. Zhao ◽  
Wei Liang ◽  
H.J. Ge
Keyword(s):  
Electric Power ◽  
Magnetic Core ◽  
Signal Extraction ◽  
Détection Signal ◽  
Current Transformers ◽  
Detection Circuit ◽  
Power Frequency ◽  
Power Metering ◽  
Secondary Side ◽  
Detection Signal

On the basis of the resistance model of high voltage electric power metering system, we make a study on the saturation of the measuring CT when the load is heavy. Through experiments on measuring current transformers, we chose high-quality power frequency magnetic core of the least saturation. On the secondary side of the measuring CT, circuit debugging was carried on and through experiments, optimal circuit parameters were determined to optimize the detection circuit which reduced the resistance of the secondary side of the measuring CT to the utmost to decrease the magnetic flux in the magnetic core to weaken saturation. Through FIR filter we extract detection signal from the fault signal to diagnose the fault. The practical test show the extracted detection signal can accurately judge the fault.

Magnetic Flux Density under Single Harmonic Distortion

2021 ◽  
Vol 1034 ◽  
pp. 151-157
Author(s):  
Michał Kaczmarek ◽  
Ernest Stano
Keyword(s):  
Magnetic Flux ◽  
Flux Density ◽  
Phase Angle ◽  
Harmonic Distortion ◽  
Magnetic Core ◽  
Magnetic Flux Density ◽  
Higher Harmonics ◽  
Secondary Voltage ◽  
Magnetizing Current ◽  
Higher Harmonic

In the paper the change of the magnetic flux density under single harmonic distortion is discussed. Presented results show the dependence of the value of the magnetic flux density in the toroidal magnetic core made from the Ni80Fe20 tape of the phase angle of higher harmonic in relation to the main harmonic of distorted magnetizing current. Moreover, the influence of higher harmonic depends from it frequency and it becomes undetectable above 15th higher harmonic, even if its level reaches 50% of the RMS value of the main harmonic of distorted magnetizing current. Laboratory tests were carried out for the magnetic toroidal core of iCT with a current ratio equal to 300 A / 5 A. The oscilloscope is used to measure waveforms of the excitation current and the secondary voltage through the voltage probes. Build in numerical integration is used to determine the magnetic flux density from secondary voltage. In the case of tested 5th higher harmonic the highest value of the magnetic flux density is obtained for phase angle equal to 90° between main and higher harmonics, while the lowest is obtained for 270°. This depends from the initial phase of the magnetic field strength and results from the integration of distorted secondary voltage with the particular content of higher harmonics.

scholarly journals Why Should We Test the Wideband Transformation Accuracy of Medium Voltage Inductive Voltage Transformers?

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4432
Author(s):  
Michal Kaczmarek ◽  
Ernest Stano
Keyword(s):  
Low Power ◽  
Magnetic Core ◽  
Sinusoidal Voltage ◽  
Higher Harmonics ◽  
Medium Voltage ◽  
Phase Displacement ◽  
Secondary Voltage ◽  
Instrument Transformers ◽  
Multiple Frequencies ◽  
Limiting Values

In this paper the results of the tests of the wideband transformation accuracy of medium voltage (MV) inductive voltage transformers (VTs) in the frequencies range from 50 Hz up to 5 kHz are presented. The values of voltage error and phase displacement for transformation of the harmonics of distorted primary voltages are determined. In the case of a typical 50 Hz-type inductive VT with a rated primary voltage equal to (15/Ö3) kV and (20/Ö3) kV manufactured by an international company the limiting values of the accuracy classes extension for quality metering required by the standard IEC 61869-6 for the Low Power Instrument Transformers (LPIT) were not exceeded. While, in the same test other MV inductive VTs show poor accuracy and even resonance at multiple frequencies. Unfortunately, this problem also arises from nonlinearity of the magnetization characteristic of their magnetic core. Therefore, for transformation of the sinusoidal voltage in the secondary voltage significant but not easily detectable values of the low order higher harmonics are present. Moreover, for transformation of harmonics of distorted primary voltage the influence of connected capacitance on the obtained values of voltage error and phase displacement was tested.

An electronically enhanced magnetic core for current transformers

1991 ◽  
Vol 40 (2) ◽  
pp. 410-414 ◽  
Author(s):  
P.N. Miljanic ◽  
E. So ◽  
W.J.M. Moore
Keyword(s):  
Magnetic Core ◽  
Current Transformers

scholarly journals Comparison of Mathematical Methods for Compensating a Current Signal under Current Transformers Saturation Conditions

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7273
Author(s):  
Ismoil Odinaev ◽  
Aminjon Gulakhmadov ◽  
Pavel Murzin ◽  
Alexander Tavlintsev ◽  
Sergey Semenenko ◽  
...  
Keyword(s):  
Magnetic Core ◽  
Electromagnetic Current ◽  
Measured Signal ◽  
Current Signal ◽  
Secondary Circuit ◽  
Mathematical Methods ◽  
Current Transformers ◽  
Advantages And Disadvantages ◽  
The Stability ◽  
A Current

Current measurements from electromagnetic current transformers are essential for the construction of secondary circuit systems, including for protection systems. Magnetic core of these transformers are at risk of saturation, as a result of which maloperation of protection algorithms can possibly occur. The paper considers methods for recovering a current signal in the saturation mode of current transformers. The advantages and disadvantages of methods for detecting the occurrence of current transformers core saturation are described. A comparative analysis of mathematical methods for recovering a current signal is given, their approbation was carried out, and the most promising of them was revealed. The stability and sensitivity of recovery methods were tested by adding white noise to the measured signal and taking into account the initial flux density (remanent magnetization) in the current transformers core. Their comparison is given on the basis of angular, magnitude, and total errors at a given simulation interval.

Alternate Current Transformers

1896 ◽  
Vol 42 (1084supp) ◽  
pp. 17330-17331
Author(s):  
J. A. Fleming
Keyword(s):  
Alternate Current ◽  
Current Transformers
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