INFLUENCE OF THE REMNANT MAGNETIZATION OF THE CURRENT TRANSFORMER CORES UPON THE COMPLIANCE OF THEIR TECHNICAL CHARACTERISTICS WITH THE REQUIREMENTS FOR MICROPROCESSOR TYPE PROTECTIVE RELAYS

2021 ◽  
Vol 2021 (3-4) ◽  
pp. 77-84
Author(s):  
Sergey Morozov ◽  
Andrey Morozov
Keyword(s):  
Circuit Breaker ◽  
Current Transformer ◽  
Remnant Magnetization ◽  
Current Transformers ◽  
Saturation Time ◽  
Backup Protection ◽  
Technical Requirements ◽  
Protective Relays ◽  
Dc Component ◽  
Methods Analytical

Work objective is finding rational technical and economic solutions for examining current transformers for techspecs compliance satisfying the requirements of reinstalled microprocessor type protective relays and automation devices manufactured by NP EKRA LLC, taking into account DC component. Research methods: analytical methods for calculating the time of remnant magnetization in the core of a current transformer. Research results and novelty: it is understood that the saturation time of current transformers of the basic and backup protections, according to the results of the analytical method, was more than 25 ms, and for current transformers of differential bus bar protection was more than 5 ms. The obtained saturation time values for all types of current transformers built into oil circuit-breaker bushings (HV line) of 110 kV and bus bar coupling connector (BCC) of 110 kV (main protection, backup protection, differential bus protection), both in the absence and in the presence of remanent induction magnetic in CT cores with three-phase and single-phase short circuits, satisfy completely technical requirements either of microprocessor type protective relays or CT differential bus bar protection. Conclusion: built into CT BCC circuit-breaker bushings of 110 kV and oil circuit-breaker bushings (HV line) of 110 kV Foundry substations do not necessitate a mandatory replacement in case of non-complex redesign of microprocessor type protective relays and automation devices. When replacing oil circuit breakers with gas-insulated ones, it is recommended to use CT with similar characteristics.

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.

Simulation Model for Assessing Operational Performance of Current Transformers

2007 ◽  
Vol 18-19 ◽  
pp. 71-77
Author(s):  
I. Sule
Keyword(s):  
Simulation Model ◽  
Current Transformer ◽  
Operational Performance ◽  
Current Transformers ◽  
Correct Operation ◽  
Operational Conditions ◽  
Secondary Current ◽  
Protection Scheme ◽  
The Core ◽  
Instrument Transformers

In determining the correct operation of relays of a protection scheme, proper representation of instrument transformers and their behavior in conditions where there can be saturation, is very critical. The main objective of this paper is to develop simulation model for assessing the operational performance of Current Transformer (CT). In order to test the validity of the developed model, three cases of CT operational conditions were considered, with data collected from Gombe, 330/132/33kV PHCN substation. The simulation results revealed various configuration performance responses that could affect relay protective schemes to different degrees. The CT responses revealed that the secondary current and voltage were distorted when the core flux linkages exceeded the set 9.2 pu saturation limit. It is concluded that the model developed for the CT of interest yield satisfactory results.

Error Calculating and Compensating Method of All-Optical Fiber Current Transformer in ± 10 kV DC Distribution Network

2019 ◽  
Vol 14 (11) ◽  
pp. 1606-1615
Author(s):  
Jicheng Yu ◽  
Changxi Yue ◽  
Jun Li ◽  
Dengyun Li ◽  
He Li
Keyword(s):  
Optical Fiber ◽  
Distribution Network ◽  
Current Transformer ◽  
Electromagnetic Current ◽  
Current Transformers ◽  
Wave Plate ◽  
Remote Transmission ◽  
Dc Distribution ◽  
All Optical ◽  
Database Technology

Current transformer is one of the main equipment in ±10 kV DC distribution network. Traditional electromagnetic current transformer has poor anti-jamming capacity and poor insulation, so it cannot realize transient protection. The emergence of all-optical fiber current transformer brings solutions to these problems, which has attracted more and more attention. In this study, aiming at the problem of error and compensation of λ/4 waveform of all-fiber current transformer, the fabrication method of λ/4 waveform is studied, the mathematical model of the waveform is established, the influence of the waveform error on the scale factor is analyzed, and a calculating device of angle difference and ratio difference to compare the error is designed. The device adopts the principle of traceability of quantities to collect the state data of the wave plate. At the same time, in order to collect data for errors, database technology and network technology are used to realize remote transmission of monitoring data. The error of the λ/4 wave plate is compensated, the bidirectional principle generated by the birefringence in the fiber ring is analyzed, and the data logic description of the transformer sensitive ring is performed. The phase delay and the angle of the shaft are selected as the main factors causing the error. Compensation is performed by means of peak segmentation and variable cancellation. In the experimental process, compared with the error sampling of the traditional transformer, the error calculated by the current amplitude and phase angle parameters obtained by the all-fiber current transformer is more accurate, and the compensation scheme can suppress the size of the birefringence and improve sensing accuracy of fiber optic current transformers. This study provides a powerful reference for the error analysis of all-fiber current transformer λ/4 wave plates, which is beneficial to promote the better application of such current transformers.

Wide-Area Backup Protection Algorithm Based on Earth Impedance Comparison Principle

2014 ◽  
Vol 513-517 ◽  
pp. 858-862
Author(s):  
Zhen Xing Li ◽  
Qiu Li ◽  
Tao Zhang
Keyword(s):  
Area Measurement ◽  
Wide Area ◽  
Differential Protection ◽  
Circuit Breakers ◽  
Backup Protection ◽  
Wide Area Measurement System ◽  
Component Identification ◽  
Current Differential Protection ◽  
Protective Relays ◽  
Bus Voltage

A novel algorithm is proposed for the purpose of improving the reliability and sensibility of fault component identification of wide area backup protection. The algorithm, called earth impedance comparison protection (EICP), is realized by comparing the ratios of different nodes, and the ratio is obtained by the bus voltage to the differential current. The advantages of EICP are verified in this paper using the measurement function of wide-area measurement system. The results of case studies show that EICP is superior to the current differential protection in terms of the sensitivity and to the directional pilot protection in terms of the dependability. The satisfactory results can be obtained when the EICP method is applied in the event of abnormal operations of protective relays and circuit breakers, measurement error scenarios or substation DC failure.

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.

DESIGN AND TEST OF A NEW HIGH-CURRENT ELECTRONIC CURRENT TRANSFORMER WITH A ROGOWSKI COIL

2014 ◽  
Vol 21 (1) ◽  
pp. 121-132 ◽  
Author(s):  
Ming Zhang ◽  
Kaicheng Li ◽  
Shunfan He ◽  
Jun Wang
Keyword(s):  
Dynamic Range ◽  
Partial Evaluation ◽  
Current Transformer ◽  
Rogowski Coil ◽  
High Current ◽  
Current Transformers ◽  
Electronic Current Transformer ◽  
Electronic Current ◽  
Electro Magnetic ◽  
Electronic Current Transformers

Abstract This paper describes the design and test of a new high-current electronic current transformer based on a Rogowski coil. For better performances, electronic current transformers are used to replace conventional electro-magnetic inductive current transformers based on ferromagnetic cores and windings to measure high-current on the high voltage distribution grids. The design of a new high-current electronic current transformer is described in this paper. The principal schemes of the prototype and partial evaluation results are presented. Through relative tests it is known that the prototype has a wide dynamic range and frequency band, and it can allow high accuracy measurements.

Electrical Network Modeling and Electrical Transfer Simulation of C.N. Asco´ I and C.N. Asco´ II, to Obtain Voltage and Frequency Limit Values Allowing the Electrical Transfer From the Main Generator to the External 110 kV Power Grid

2009 ◽  
Author(s):  
Alberto Ban˜o´ Azco´n ◽  
Jose´ Mollera Barriga
Keyword(s):  
Power Supply ◽  
Power Grid ◽  
Circuit Breaker ◽  
Operating Mode ◽  
Electrical Network ◽  
Limit Values ◽  
Electric System ◽  
Future Design ◽  
Turbo Generator ◽  
Protective Relays

Broadly speaking, a simple electrical diagram of Asco´ I and Asco´ II power nuclear plants could be two power supply bus bars for general equipment classified No-1E, three power supply bus bars class No-1E for the Reactor Coolant Pumps (RCP) and two more bus bars classified 1E for safety related equipment. In normal operating mode, all the five power supply bus bars class No-1E are connected to the main generator (GP1) through two unit transformers (TAG1/2), while the two class 1E power supply bus bars are always connected to an external 110 kV power grid through two auxiliary transformer (TAA1/2). The main generator supplies power to an external 400 kV grid through the main transformer (TP1). The main circuit breaker is placed between the high voltage side of the main transformer and the 400 kV grid. With this configuration, the appearance of an abnormal condition that originates the trip of the main generator and the opening of the main circuit breaker from the external network, involves an electric transfer of the supply bus bars connected to the turbo generator to the external 110 kV power grid. The electric transfer to the external 110 kV power grid will be only possible if the frequency and voltage values are within the allowed range allowed by the grid’s protective relays. Two kinds of electrical transfers are possible: fast transfers and slow transfers. It will be necessary then to evaluate the limit values of voltage and frequency of the power grid that makes the electrical transfer possible in each case. In order to obtain the limit values previously mentioned, the electric system of the plant has been modeled. Different scenarios have been analyzed, taking into account the dynamic behavior of the system components and the delay of the protective relays actuation, verifying the electrical transfer for those situations. This analysis will give enough information to take the correct decisions for future design modifications, and it will assure that the electrical transfer will be done always with success.

scholarly journals The.main types of wind turbines-generators in the power supply system

2022 ◽  
Vol 23 (5) ◽  
pp. 71-85
Author(s):  
V. A. Novobritsky ◽  
D. S. Fedosov
Keyword(s):  
Second Harmonic ◽  
Short Circuit ◽  
Separation Of Variables ◽  
Harmonic Component ◽  
Relay Protection ◽  
Short Circuit Current ◽  
Current Transformer ◽  
Correct Operation ◽  
Protection Devices ◽  
Dc Component

THE PURPOSE. This paper considers the problem of relay protection functioning when the current transformer reaches the saturation mode which is provided by transient processes.METHODS. MATLAB Simulink software environment allows reproducing the method of statespace representation by using structural blocks. The model is verified by comparison the time to saturation, obtained by calculation and according to the graphical data of the model. The separation of variables method extracts and graphically displays the investigated components.RESULTS. This paper reveals that applying the requirements of IEC 61869-2:2012 standard, which determines the worst combination of series of unfavorable factors for current transformers in transient mode, can influence a serious impact on the correct operation of relay protection based on current, reactance or differential principle of action. Saturation of the current transformer can lead to both negative results: false operation of relay protection devices and their failure.CONCLUSION. According to the results of the study, it was determined that the presence of a DC component in the primary short-circuit current has the greatest effect on the protection operation. The delays in the restoration of the RMS value of the short-circuit current reached up to 0.3 seconds, which is comparable with the response time of the second protection zones for microprocessor-based relay protection devices. The DC component of the primary current and the presence of residual magnetic induction of the current transformer provides the largest content of the magnetization current, the largest angular error and also the largest content of the second harmonic component in the secondary short-circuit current.

scholarly journals Use of statistical analysis methods in processing population survey data

2021 ◽  
pp. 58-60
Author(s):  
Vasilij Kalinchik ◽  
Vitaliy Pobigaylo ◽  
Vitaliy Kalinchyk ◽  
Daniil Filjanin
Keyword(s):  
Total Error ◽  
Current Transformer ◽  
Measuring Channel ◽  
Measuring Circuit ◽  
Metrological Characteristics ◽  
Measuring Instruments ◽  
Voltage Transformer ◽  
Current Transformers ◽  
Collection Device ◽  
Communication Lines

The article analyzes the structures of the measuring channels of electricity metering systems. It is shown that such a structure is determined by the types of measuring instruments used and the scheme of their connection, in particular, by the types of electricity meters installed at the metering points. Moreover, the counters can have a pulse or interface information output. It is shown that the path for measuring and metering electricity includes a measuring circuit consisting of measuring current and voltage transformers, an electricity meter, communication lines, a metering device and a data collection device. The applied method is based on the standardization of the metrological characteristics of individual elements of the measuring path and their synthesis based on the metrological characteristics of the entire electricity metering system. To calculate the total error of the measuring channel, a formula is used that takes into account only the errors of the measuring circuit. It is shown that in recent years there has been a tendency when measuring current transformers and, accordingly, electricity meters operate in the mode of low current loads. In this case, the errors of the elements of the measuring path are poorly studied. The graphs of errors of current transformers depending on load currents are given. It is shown that the values of the errors of current transformers vary with the magnitude of the load current and are in the region of negative values. Therefore, the wrong choice of current transformers can lead to a significant underestimation of electricity. The errors of voltage transformers depend mainly on the load on the secondary winding and do not significantly affect the total error. The resulting error of the measuring path current transformer - voltage transformer - electricity meter in the area of low loads is given. A change in errors in the area of low loads leads to serious metrological losses (underpayment of electricity). In the automation of electricity metering, graphs of changes in errors in the area of low loads are presented, which can serve as a basis for correcting the error of the measuring paths.

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