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.

scholarly journals Improvement of Algorithm for Formation of Orthogonal Components of Input Quantities in Microprocessor Protection

2021 ◽  
Vol 64 (2) ◽  
pp. 95-108
Author(s):  
F. A. Romaniuk ◽  
Yu. V. Rumiantsev ◽  
V. Yu. Rumiantsev ◽  
I. V. Novash
Keyword(s):  
High Speed ◽  
Block Diagram ◽  
Short Circuit ◽  
Digital Device ◽  
Measuring Devices ◽  
Input Signals ◽  
Orthogonal Components ◽  
Mode Of Occurrence ◽  
Aperiodic Component ◽  
Microprocessor Protection

The use of orthogonal components (OC) underlies  the construction of measuring elements of  modern protection and automation devices. In most microprocessor-based protections, the orthogonal component of the input signal is extracted using a discrete Fourier transform (DFT). The DFT disadvantages are its low speed, which is more than one period of the fundamental frequency, as well as the sensitivity to the free aperiodic component, which creates significant conversion errors depending on the time constant of its decay. Such a settling time of the true output signal is often unacceptable for the design of high-speed measuring devices. The paper proposes to form the OC of the equivalent signal according to the values of the cosine and sine OC of the fundamental harmonic, formed using the DFT by multiplying them by the resulting correction factor. The developed algorithm for the formation of orthogonal components of input signals in microprocessor protections is characterized by high speed in transient modes and it has wide functionality. So, the proposed digital device for forming the orthogonal components of an equivalent signal, in comparison with digital filter based on the DFT, has an increased operating speed both in the mode of occurrence of a short circuit and during the decay of the monitored signal, while maintaining the same characteristics as in the DFT in other modes. A block diagram of the proposed digital device for forming the OC of an equivalent signal has been developed, all blocks of which can be implemented on a microelectronic and microprocessor element base. A digital model of the specified device has been developed in the dynamic modeling system MatLab-Simulink in accordance with the structural diagram. As a result of the calculations, a significant (up to two times) increase in the performance of the proposed digital device for forming the OC in transient modes has been established in comparison with the shapers based on the DFT.

scholarly journals AUTOMATION OF THE HEAT STATE ANALYSIS PROCESS HIGH-VOLTAGE CURRENT TRANSFORMERS

2019 ◽  
pp. 96-110
Author(s):  
V. M. Kutin ◽  
M. V. Nikitchuk ◽  
V. M. Svitko ◽  
O. O. Shpachuk
Keyword(s):  
Expert Knowledge ◽  
Thermal State ◽  
Statistical Processing ◽  
Electrical Equipment ◽  
Technical Condition ◽  
Mobile Systems ◽  
Electric Networks ◽  
Structural Element ◽  
Operating Life ◽  
Current Transformers

Thermographic control of electrical equipment allows you to draw preliminary conclusions about the technical condition of insulation, contact joints, windings, structural elements and cooling systems of electrical equipment of voltage classes 0.4 ÷ 750 kV. However, it should be borne in mind that the results of temperature measurement and assessment of the thermal state of electrical equipment are influenced by such factors as: environmental conditions, qualifications of personnel performing thermographic control and data interpretation, the need to improve regulatory documents for assessing the thermal state of electrical equipment and develop unified algorithms analysis of the results of thermographic examinations and gradation of the development of defects in electrical equipment. Modern research in the field of thermographic control of electrical equipment is developing in several directions, namely: the use of automated (stationary or mobile) systems for collecting thermographic data; development of algorithms for processing thermal images that reduce the influence of extraneous noise on the values of the measured temperatures, select the image of the object being examined, select the optimal level of contrast of the thermal image to detect thermal anomalies; using statistical processing of thermal fields of thermal monitoring objects and making decisions about the thermal state of equipment using neural networks, machine learning and expert knowledge. Automation of the analysis of thermographic control data is an urgent scientific and practical task, the solution of which will improve the quality of maintenance, repairs, extension of the operating life and operational management of electrical equipment in conditions of a significant level of aging of the main production assets of electric companies and change of generations of staff. Measuring current transformers of voltage classes 330 ÷ 750 kV are critical elements in the distribution schemes of electric power and in electric networks, and their technical condition directly affects the reliability of electric networks and power supply to consumers. The paper considers the reasons for the development of defects in current transformers of voltage classes 330 ÷ 750 kV, and also proposes relationships to take into account the influence of the air flow rate and the actual value of the emissivity of the structural element of the current transformers, as well as elements of the algorithms for analyzing data from thermal imaging surveys to reduce the influence of environmental factors and qualification level of the personnel performing the analysis, diagnostic results.

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.

Investigation on Dynamic Properties of Amorphous Magnetic Core Stimulated by Different Driving Voltages

2019 ◽  
Vol 47 (10) ◽  
pp. 4536-4540 ◽  
Author(s):  
Song Li ◽  
Jingming Gao ◽  
Hanwu Yang ◽  
Xingjun Ge ◽  
Zhaohua Liu ◽  
...  
Keyword(s):  
Dynamic Properties ◽  
Magnetic Core

Topology optimization of magnetic cores for WPT using the geometry projection method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yoshitsugu Otomo ◽  
Hajime Igarashi
Keyword(s):  
Topology Optimization ◽  
Projection Method ◽  
Optimization Method ◽  
Magnetic Core ◽  
Material Distribution ◽  
Coupling Coefficients ◽  
Content Type ◽  
Magnetic Cores ◽  
Geometry Projection ◽  
Topology Optimization Method

Purpose The purpose of this study is to search for an optimal core shape that is robust against misalignment between the transmitting and receiving coils of the wireless power transfer (WPT) device. During the optimization process, the authors maximize the coupling coefficients while minimizing the leakage flux around the coils to ensure the safety of the WPT device. Design/methodology/approach In this study, a novel topology optimization method for WPT devices using the geometry projection method is proposed to optimize the magnetic core shape. This method facilitates the generation of bar-shaped magnetic cores because the material distribution is represented by a set of elementary bars. Findings It is shown that an optimized core shape, which is obtained through topology optimization, effectively increases the net magnetic flux interlinked with the receiving coil and outperforms the conventional core. Originality/value In the previous topology optimization method, the material distribution is represented by a linear combination of Gaussian functions. However, this method does not usually result in bar-shaped cores, which are widely used in WPT. In this study, the authors propose a novel topology optimization method for WPT devices using geometry projection that is used in structural optimization, such as beam and cantilever shapes.

On the Problem of Selecting and Replacing Current Transformers for Relay Protection Devices

2020 ◽  
Vol 63 (6) ◽  
pp. 72-82
Author(s):  
Stanislav Kuzhekov ◽  
◽  
Andrey Degtyarev ◽  
Nikolay Doni ◽  
Aleksey Shurupov ◽  
...  
Keyword(s):  
Power Systems ◽  
High Speed ◽  
Short Circuit ◽  
Relay Protection ◽  
Electric Power Systems ◽  
Current Transformers ◽  
Magnetic Cores ◽  
Protection Devices ◽  
Short Circuits ◽  
The Stability

In connection with cases of incorrect operation of high-speed relay protection devices (RPD) in case of short circuits outside their range, the issue of replacing current transformers (CT) of class P with more ad-vanced current converters is relevant. The article shows that the decision to replace existing class P CTs with CTs with a non-magnetic gap should be made taking into account the probability of saturation of the magnetic cores of the latter in a transient short-circuit mode, as well as an increase in their dimensions compared to class P CTs. The issue of using optoelectronic current converters should be resolved after the latter are put into mass production, taking into account the difficulty of integrating the latter with the RPDs implemented using an Electromechanical base. In many cases, the correct functioning of high-speed RPDs without replacing existing CTs of class P can provide the following measures: the use of algorithms that increase the stability of the oper-ation of high-speed RPDs when the CT is saturated; taking into account in the calculations of the settings the rectangular characteristic of the CT magnetization in transient modes and the permissible deceleration of pro-tections under the condition of the dynamic stability of electric power systems; refusal to use CT connection groups (physical sum of currents, delta and star).

Automatic addition

1963 ◽  
Vol 10 (3) ◽  
pp. 127-132
Author(s):  
Franz E. Hohn
Keyword(s):  
Magnetic Tape ◽  
Number System ◽  
Magnetic Core ◽  
The Other ◽  
Binary Number ◽  
Magnetic Cores ◽  
Related Machines

Computers and related machines employ devices such as switches, electron tubes, transistors, magnetic cores, magnetic tape, and so on to do their work of storing, processing, and computing numbers. Since a switch is either open or closed, a tube or transistor is either conducting electricity or not conducting electricity, and a magnetic core or a spot on a magnetic tape is magnetized either “positively” or “negatively,” that is, since one of two opposite conditions is always present, it is natural that the internal operation of such machines should be based on the binary number system, which counts by twos. One of the two conditions is used to represent the number 1, the other to represent the number 0.

Superhydrophobic magnetic core–shell mesoporous organosilica nanoparticles with dendritic architecture for oil–water separation

2020 ◽  
Vol 4 (7) ◽  
pp. 2184-2191 ◽  
Author(s):  
Baixian Wang ◽  
Yingzhen Wei ◽  
Qifei Wang ◽  
Jiancheng Di ◽  
Shiding Miao ◽  
...  
Keyword(s):  
Magnetic Core ◽  
Core Shell ◽  
Water Separation ◽  
Magnetic Cores ◽  
Mesoporous Organosilica ◽  
Oil In Water ◽  
Oil Water Separation ◽  
Oil Water

Superhydrophobic dendritic mesoporous organosilica nanoparticles with magnetic cores were fabricated, realizing the efficient adsorption of oils from oil-in-water emulsions.

Characteristics of Fe-Si-B-Cr-C Powders Synthesized by the Spinning Water Atomization Process (SWAP) and its Application in Magnetic Core

2015 ◽  
Vol 749 ◽  
pp. 101-105
Author(s):  
Shih Fan Chen ◽  
Shih Hang Huang ◽  
Shea Jue Wang ◽  
Jin Shyong Lin ◽  
Shih Hsun Chen ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Saturation Magnetization ◽  
Quality Factor ◽  
Magnetic Core ◽  
Atomization Process ◽  
Magnetic Cores ◽  
Water Atomization ◽  
Quality Factor Q ◽  
Maximum Permeability

The application properties of magnetic cores made of Fe72.8Si11.2B10.8Cr2.3C2.9 powders was studied. The amorphous Fe72.8Si11.2B10.8Cr2.3C2.9 powders were prepared by a spinning water atomization process (SWAP), and the cores further were fabricated from those powders by a hydraulicpressing process. The particle size distribution of powders was about 10 to 20 μmand the alloy powders would crystallize during milling. For the cores, the maximum permeability μi was 14 and quality factor Q was 84 between 100kHz - 2000kHz for 1 wt.% Na2SiO4solidified with H-epoxy at 300°C. The minimum coercivityHcwas 0.22 Oe at 1 wt.% Na2SiO4 with PVB consolidated at 150 °C, and the maximum saturation magnetization Bm was 7.64×102 G for 2 wt.% Na2SiO4 with H-epoxy at 300 °C.

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