Simulation and Analysis for Current Transformers with DC Bias and Remnant Flux

2013 ◽  
Vol 765-767 ◽  
pp. 2430-2434
Author(s):  
Xiao Qian Tian ◽  
Bao Shu Li ◽  
Lu Shen
Keyword(s):  
Error Compensation ◽  
Current Transformer ◽  
Scientific Basis ◽  
Current Transformers ◽  
Ratio Error ◽  
Full Wave ◽  
Accuracy Of Measurement ◽  
Dc Bias ◽  
Power Metering ◽  
Fourier Algorithm

The transfer characteristics of current transformers (CT) change due to DC bias, which directly impacts the accuracy of measurement and power metering. Based on equivalent circuit models and core magnetizing characteristic, qualitatively analysis current transformer saturation increase errors of CT. Transfer errors under DC bias and remnant flux are also obtained based on J-A model of CT in PSCAD/EMTDC and full-wave Fourier algorithm to show that the ratio error and phase displacement increase with the DC bias. Based on FFT spectrum analysis to identify remnant flux and DC bias provides scientific basis for error compensation of CT.

Influence of DC Bias and Remnant Flux on Measuring Current Transformers

2013 ◽  
Vol 765-767 ◽  
pp. 2268-2271
Author(s):  
Lu Shen ◽  
Shu Tao Zhao ◽  
Pei Zhang ◽  
Bin Hu ◽  
Xiao Qian Tian
Keyword(s):  
Power Systems ◽  
Electric Energy ◽  
Current Transformer ◽  
Simulation Software ◽  
Ratio Error ◽  
Phase Displacement ◽  
Limit Value ◽  
Exciting Current ◽  
Energy Metering ◽  
Dc Bias

Current transformer (CT) is an important transmission equipment in power systems. DC bias and remnant flux can change the working point of CT in the core magnetization curve and has a direct impact on the accuracy of electric energy metering and measurement. The simulation circuit model is built by using the simulation software PSCAD and the change of ratio error, phase displacement and exciting current with DC bias and remnant flux are analyzed. The results show that DC bias and remnant flux will both increase the ratio error and phase displacement in opposite directions and the error size will be far more than the limit value when DC bias and remnant flux exist in same direction at the same time. Furthermore, the existence of DC bias and remnant flux will also cause the raise of exciting current size, asymmetry of exciting current waveform and appearance of even harmonics. This will seriously affect the transmission accuracy of measuring CT.

Error Analysis for Metering Current Transformer with DC Bias

2013 ◽  
Vol 773 ◽  
pp. 58-61
Author(s):  
Shi Hai Yang ◽  
Ke Qi Zhang ◽  
Zhong Zhuang ◽  
Min Rui Xu ◽  
Min Jian Cao ◽  
...  
Keyword(s):  
Error Analysis ◽  
Power System ◽  
Simulation Model ◽  
Digital Simulation ◽  
Current Transformer ◽  
Angle Error ◽  
Ratio Error ◽  
Dc Bias ◽  
Simulation Results ◽  
Different Levels

DC bias widely exists in power system. In order to analyze its influence on metering current transformer (MCT), a new digital simulation model based on Preisach theory is constructed firstly. Using this digital model, the ratio error and angle error of a running MCT are calculated under different levels of DC bias. Simulation results show that the current DC bias in power system has only little influence on the error of MCT.

scholarly journals The Research on Anti-DC current Transformer of Dual Iron Core Structure with Air Gap

2021 ◽  
Vol 2133 (1) ◽  
pp. 012030
Author(s):  
Zhongai Lin ◽  
Xingyi Zhang ◽  
Biao Tang ◽  
Feng Shen
Keyword(s):  
Electrical Measurement ◽  
Current Transformer ◽  
Air Gap ◽  
System Stability ◽  
Iron Core ◽  
Saturation Current ◽  
Angle Error ◽  
Ratio Error ◽  
Dc Bias ◽  
Dc Current

Abstract Current transformer (CT) is wildly used in electrical measurement and relay protection. In order to improve the power system stability in DC bias, the CT performance of anti-DC is necessarily to be enhanced. Based on the Jiles-Atherton theory, the magnetization characteristics of iron core with different air gap was analyzed in this paper. A simulation model was established using the Simulink toolbox, and the ratio error and angle error were investigated in different air gap length. Simulation result shows that the maximum magnetic density of iron core almost stays uncharged with the addition of air gap. Furthermore the slope of magnetization curve decreased, which leads to the increase of iron core saturation current. Current transformer with closed and air gap iron core possesses a stable measurement error in condition of severe DC bias.

On-Line Evaluation of Voltage Transformer Accuracy

2012 ◽  
Vol 433-440 ◽  
pp. 6071-6076 ◽  
Author(s):  
Xiao Hui Yang ◽  
Dong Yan ◽  
Kai Xie ◽  
Yong Wang
Keyword(s):  
Evaluation System ◽  
Current Transformer ◽  
Test Results ◽  
Voltage Transformer ◽  
Ratio Error ◽  
Key Factor ◽  
On Line ◽  
Power Metering ◽  
Site Test ◽  
Key Techniques

The accuracy of voltage and current transformer (VT and CT) is a key factor in electric power metering. Ratio error and phase displacement calibration of VT and CT is traditionally carried out off-line. As a result of the expansion of the power grid and the increasing metering quality requirements from customer side, the off-line metering of VT and CT becomes more and more difficult. In this paper, a VT accuracy on-line evaluation system is developed, which can evaluate the accuracy of VT under on-line operating status. The principle and adopted key techniques in the development of the VT accuracy on-line evaluation system is introduced. Some on-site test results are also presented and analyzed as application demonstration.

Thermal Overload Protection for AC Asynchronous Motor Based on Complex Morlet Wavelet

2015 ◽  
Vol 740 ◽  
pp. 364-367
Author(s):  
Su Wang ◽  
Lei Sun ◽  
Wei Cong Huang
Keyword(s):  
Asynchronous Motor ◽  
Morlet Wavelet ◽  
Algorithm Analysis ◽  
Full Wave ◽  
Overload Protection ◽  
Dc Component ◽  
Complex Morlet Wavelet ◽  
Fourier Algorithm ◽  
Wavelet Algorithm ◽  
Better Than

Conventionally, the fault signal of motor thermal overload in a non-periodic component is not effectively filtered with Full-wave Fourier Algorithm (or FFA). In this paper, a design which combined Complex Morlet Wavelet Algorithm with Subtraction (or CMWAS) filter is presented. The design gives system model of overload and algorithm analysis It is verified that the new algorithm is better than the FFA algorithm in terms of filtering decaying DC component.

A novel error compensation algorithm for three-current transformer connection

2010 ◽  
Vol 32 (5) ◽  
pp. 416-420 ◽  
Author(s):  
Qing-quan Jia ◽  
Chun-xia Dou ◽  
Chun Wang ◽  
Ning Wang ◽  
Jie Tian ◽  
...  
Keyword(s):  
Error Compensation ◽  
Current Transformer ◽  
Compensation Algorithm

Design and Analysis of PCB Rogowski Coil Current Transformer

2014 ◽  
Vol 672-674 ◽  
pp. 984-988
Author(s):  
Biao Su ◽  
Li Xue Li ◽  
Yi Hui Zheng ◽  
Xin Wang ◽  
Yan Liu ◽  
...  
Keyword(s):  
Power System ◽  
High Sensitivity ◽  
Current Transformer ◽  
Rogowski Coil ◽  
Electromagnetic Current ◽  
Current Transformers ◽  
Coil Current ◽  
Electronic Current ◽  
Rogowski Coils ◽  
Electronic Current Transformers

Electronic current transformers are more suitable for the development of power system compared with traditional electromagnetic current transformers. Rogowski coil current transformer is one of three electric current transformers. According to the measurement principle of Rogowski coils, the equivalent circuit of PCB Rogowski coils is analyzed. By using four PCB Rogowski coils combined, a PCB Rogowski coil current transformer is designed and tested. The results show that the designed PCB Rogowski coil transformer has good linearity and high sensitivity and measurement accuracy and it can meet the requirement of power system.

Measurement Current Transformer Error Compensation by ANN Methodology

2020 ◽  
Vol 101 (3) ◽  
pp. 261-271
Author(s):  
Makarand Sudhakar Ballal ◽  
Manish Ganesh Wath ◽  
Hiralal Murlidhar Suryawanshi
Keyword(s):  
Error Compensation ◽  
Current Transformer

Study of an accurate electronic power measurement technique using modified current transformer and potential transformer

2019 ◽  
Vol 41 (13) ◽  
pp. 3666-3678
Author(s):  
Sirshendu Saha ◽  
Saikat Kumar Bera ◽  
Hiranmoy Mandal ◽  
Pradip Kumar Sadhu ◽  
Satish Chandra Bera
Keyword(s):  
Phase Angle ◽  
Measurement Errors ◽  
Light Emitting Diode ◽  
Current Transformer ◽  
Power Measurement ◽  
Measurement Unit ◽  
Measurement Circuit ◽  
Angle Error ◽  
Ratio Error ◽  
High Tension

In high tension power measurement, potential transformer (PT) and current transformer (CT) are used in order to reduce high tension voltage and current, respectively. But both PT and CT suffer from ratio error and phase angle error, which may produce severe error in power measurement. In the present paper, modified designs of PT and CT are combined to develop an electronic power measurement circuit in order to reduce the measurement errors. The modified PT and CT have reduced phase angle error and ratio error. In the power measurement circuit, the instantaneous product of the outputs of these PT and CT is determined by using a simple light emitting diode (LED)-light dependent register (LDR) or LED-LDR-based product circuit. The operation of the proto type power measurement unit designed in the present work has been experimentally tested and the measured outputs are compared with the readings of laboratory standard wattmeter. The experimental results are reported in the paper. Very good linear characteristics are observed.

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