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Author(s):  
V. A. Novobritsky ◽  
D. S. Fedosov

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.


Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 92
Author(s):  
Andrzej Gecow ◽  
Laszlo Barna Iantovics

Up until now, studies of Kauffman network stability have focused on the conditions resulting from the structure of the network. Negative feedbacks have been modeled as ice (nodes that do not change their state) in an ordered phase but this blocks the possibility of breaking out of the range of correct operation. This first, very simplified approximation leads to some incorrect conclusions, e.g., that life is on the edge of chaos. We develop a second approximation, which discovers half-chaos and shows its properties. In previous works, half-chaos has been confirmed in autonomous networks, but only using node function disturbance, which does not change the network structure. Now we examine half-chaos during network growth by adding and removing nodes as a disturbance in autonomous and open networks. In such evolutions controlled by a ‘small change’ of functioning after disturbance, the half-chaos is kept but spontaneous modularity emerges and blurs the picture. Half-chaos is a state to be expected in most of the real systems studied, therefore the determinants of the variability that maintains the half-chaos are particularly important in the application of complex network knowledge.


2022 ◽  
Vol 17 (01) ◽  
pp. P01019
Author(s):  
J. Maestre ◽  
C. Bahamonde ◽  
I. Lamas Garcia ◽  
K. Kershaw ◽  
N. Biancacci ◽  
...  

Abstract Beam Intercepting Devices (BIDs) are essential protection elements for the operation of the Large Hadron Collider (LHC) complex. The LHC internal beam dump (LHC Target Dump Injection or LHC TDI) is the main protection BID of the LHC injection system; its main function is to protect LHC equipment in the event of a malfunction of the injection kicker magnets during beam transfer from the SPS to the LHC. Several issues with the TDI were encountered during LHC operation, most of them due to outgassing from its core components induced by electron cloud effects, which led to limitations of the injector intensity and hence had an impact on LHC availability. The absorbing cores of the TDIs, and of beam intercepting devices in general, need to deal with high thermo-mechanical loads induced by the high intensity particle beams. In addition, devices such as the TDI — where the absorbing materials are installed close to the beam, are important contributors to the accelerator impedance budget. To reduce impedance, the absorbing materials that make up the core must be typically coated with high electrical conductivity metals. Beam impact testing of the coated absorbers is a crucial element of development work to ensure their correct operation. In the work covered by this paper, the behaviour of several metal-coated absorber materials was investigated when exposed to high intensity and high energy proton beams in the HiRadMat facility at CERN. Different coating configurations based on copper and molybdenum, and absorbing materials such as isostatic graphite, Carbon Fibre Composite (CfC) and Silicon Carbide reinforced with Silicon Carbide fibres (SiC-SiC), were tested in the facility to assess the TDI's performance and to extract information for other BIDs using these materials. In addition to beam impact tests and an extensive Post Irradiation Examination (PIE) campaign to assess the performance of the coatings and the structural integrity of the substrates, extensive numerical simulations were carried out.


ACTA IMEKO ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 46
Author(s):  
Pier Paolo Amoroso ◽  
Claudio Parente

Bathymetric surveys are carried out whenever there is a need to know the exact morphological trend of the seabed. For a correct operation of the echo sounder, which uses the principle of acoustic waves to scan the bottom and determine the depth, it is important to accurately determine the sound velocity in water, as it varies according to specific parameters (Density, Temperature, and Pressure). In this work, we want to analyse the role of sound velocity determination in bathymetric survey and its impact on the accuracy of depth measurement. The experiments are conducted on data set provided by “Istituto Idrografico della Marina Militare Italiana” (IIM), the official Hydrographic Office for Italy, and acquired in the Ligurian sea. In our case, the formulas of Chen & Millero (UNESCO), Medwin, and Mackenzie were applied. The introduction of errors on chemical-physical parameters of the water column (Temperature, Pressure, Salinity, Depth) simulating inaccurate measurements, produces considerable impacts on sound velocity determination and subsequently a decrease of the depth value accuracy. The results remark the need to use precise probes and accurate procedures to obtain reliable depth data.


2021 ◽  
Vol 28 (3) ◽  
pp. 360-377
Author(s):  
Juan J. Diaz ◽  
José A. Fernández

The objectives of this study were to develop a realistic simulation tool to analyze solar thermal cooling systems driven by Fresnel collectors and carry out a case study in which the performance of a solar cooling system of 190 kW located in Riyadh is simulated to demonstrate the functionality and potentiality of the developed tool. This tool is based on an integrated mathematical model that considers the ambient conditions, the thermal loads of the building, the pre-sizing data of each of the components of the system and the simultaneous interaction among them, to conduct a realistic, simple, and precise analysis. A demonstrative simulation example was performed. During the month of July, with a solar opening area of 704 m2 and a tank of 35200 L, a total amount of 47,5 MWh of cooling energy was obtained, with a reduced contribution of the auxiliary system (5,6 MWh) and a minimum number of solar collector system deactivation hours (0,7 %). The daily COP of the absorption machine remained above 0,69. The obtained results from the case study with the simulation tool allowed to verify its functionality, capabilities and correct operation to carry out hourly and parametric studies of this type of systems.


2021 ◽  
Vol 12 (1) ◽  
pp. 70
Author(s):  
Esteban Ruiz de Oña ◽  
María Sánchez-Aparicio ◽  
Susana Del Pozo ◽  
Diego González-Aguilera

Photovoltaic solar plants are one of the main facilities away from urban centers for the generation of clean energy. Since its appropriate maintenance ensures its suitable operation, optimizing their maintenance tasks in a preventive way is key. This article presents a spatial data infrastructure called INSPECTORMAP that, based on the analysis of free satellite images within the optical spectrum, can detect unusual vegetation and bodies of water in the vicinity of photovoltaic plants that can affect their correct operation. Thanks to the implementation of a monitoring and alert system, it is possible to know and map the status of the photovoltaic plant in terms of unusual coverages appearing, both natural and artificial, at any moment. Thus, maintenance workers would travel to the solar plant to carry out their maintenance tasks in this regard only when the system detects a risk.


Author(s):  
Artem Tret'yakov

The basic information about "IM View" software, necessary hardware for its correct operation is given. The main directions of further development of the program are outlined.


Author(s):  
Patryk Wąsik

This paper presents a fast, reliable and portable method for measuring electromagnetic disturbances in LV circuits (overcurrent circuit breakers). The experiment was carried out under conditions reflecting the real measurement environment. The method was verified and confirmed by a series of measurements with passive components reducing the disturbance. The results of the measurements made it possible to obtain suitable EMI reduction solutions, which can be used to protect commutators or end consumers. The results obtained make it possible to apply the method to measurements of multichannel circuit breakers, in which measuring the turn-on time of individual channels is important for the correct operation of the devices.


Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8444
Author(s):  
Jacek Feliks ◽  
Paweł Tomach ◽  
Dariusz Foszcz ◽  
Tomasz Gawenda ◽  
Tomasz Olejnik

The paper presents the results of research on the vibrating motion of a laboratory screen with a rectilinear (segmental) trajectory of vibrations during its start-up and braking. The investigations were carried out on a modernized stand equipped with a system of two vibrating motors applied in newer solutions of industrial screens, which are mounted directly on the riddle. The tests were carried out for three different frequencies using three-axis acceleration sensors. The analysed parameter was the increase in the amplitude of vibrations in transient states compared to the amplitude during the stable operation of the device. The maximum multiplication of the vibration amplitude of the classic drive system during start-up was 9.7 (mm/mm) in the vertical direction and 5.7 (mm/mm) for the new system. During braking, the maximum multiplication of the vibration amplitude of the classic drive system was 6.9 (mm/mm) vertically, while for the drive system with vibration motors, it was 11.4 (mm/mm). The absence of flexible couplings in the drive system reduces the damping of vibrations and increases the value of amplitude during the start-up and free braking of the machine. This does not have a major influence on the correct operation of the machine in a steady state. However, the use of the new drive system resulted in a significant reduction in power demand and shortened the start-up time, which has a positive effect on the operating costs of the machine.


Electronics ◽  
2021 ◽  
Vol 10 (23) ◽  
pp. 3046
Author(s):  
Emmanuel Hernández-Mayoral ◽  
Efraín Dueñas-Reyes ◽  
Reynaldo Iracheta-Cortez ◽  
Eduardo Campos-Mercado ◽  
Vicente Torres-García ◽  
...  

Most power quality problems for electrical grids connected to Doubly-Fed Induction Generators (DFIGs) include flicker, variations of the RMS voltage profile, and injected harmonics because of switching in power converters. These converters have different topologies with the back-to-back (B2B) topology being the most exploited in high-powered three-phase systems. Therefore, in this article a model of a DFIG connected to the B2B power converter is proposed to which different switching techniques are implemented for interharmonic propagation studies. The switching techniques that are implemented include the Sinusoidal PWM (SPWM), the third harmonic injection PWM (THIPWM), and the space vector PWM (SVPWM), to reduce the Total Harmonic Distortion (THD) index of voltage and current in both windings of the machine. MATLAB-Simulink® software is used for modeling and simulating the B2B power converter and the switching techniques. The proposed model is validated with an experimental prototype that includes a 3-kW DFIG, a 10 HP motor, a gear-box with a transmission ratio of 4.5: 1, a B2B power converter, and a three-phase transformer connecting the system to the electrical grid. Finally, it is shown that the results obtained from the experimental tests corroborate the correct operation of the proposed model.


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