scholarly journals A comparative analysis of the most common deterministic methods for the calculation of electricity losses in industrial networks

2019 ◽  
Vol 21 (5) ◽  
pp. 87-96
Author(s):  
E. I. Gracheva ◽  
Z. M. Shakurova ◽  
R. E. Abdullazyanov
Keyword(s):  
Low Voltage ◽  
Heating Temperature ◽  
Reference Method ◽  
Supply Networks ◽  
Method Of Calculation ◽  
Maximum Loss ◽  
Causes Of Errors ◽  
Load Schedule ◽  
Graphical Integration ◽  
Radial Network

: The work is devoted to the analysis of deterministic most common methods for determining electricity losses in low-voltage industrial power supply networks. The method of graphical integration, the method of calculating electricity losses using the maximum loss time, the method of determining losses by time 2t, the method of calculating electricity losses by the average node loads are considered. The features of the application of each method are revealed. It is shown that for the method of graphical integration, initial data on the dependences of load schedules for each network element are required, and the method of calculating losses by average node loads can be used in networks with relatively constant loads. We consider the methods of calculating the losses based on graphical integration, the time of largest losses, 2t and the root-mean-square loads.At the same time, the errors of the considered methods for calculating electricity losses can be due to such reasons as the neglect of the heating temperature of the conductors, the neglect of the resistances of the contact connections of switching devices, the inaccuracy of determining the values of losses during the highest and lowest power demand, the inaccuracy of determining the time of the largest losses,. disregarding the form of the load schedule of consumers.Using the example of an industrial radial network site with known load graphs of consumers, the electric power losses in the circuit lines with the specified methods were calculated with the determination of the error of each method and the identification of the causes of errors. In this case, the method of graphical integration was adopted as the reference method of calculation. As a result of the calculations, it was established that the method of calculating 2t has the smallest error. It is shown that when choosing a method for determining electricity losses, it is necessary to observe the condition of compliance with methodological and informational errors.

Urban exposure to ELF magnetic field due to high-, medium- and low-voltage electricity supply networks

2009 ◽  
Vol 137 (3-4) ◽  
pp. 214-217 ◽  
Author(s):  
V. Bottura ◽  
M. Cappio Borlino ◽  
N. Carta ◽  
L. Cerise ◽  
E. Imperial
Keyword(s):  
Magnetic Field ◽  
Low Voltage ◽  
Electricity Supply ◽  
Supply Networks ◽  
Elf Magnetic Field

scholarly journals Improvement of the Method of Calculation of Steady-State Modes of Urban Electric Networks Taking into Account Consumer Energy Sources

2019 ◽  
Vol 62 (6) ◽  
pp. 514-527
Author(s):  
M. I. Fursanov ◽  
A. A. Zalotoy
Keyword(s):  
Steady State ◽  
Low Voltage ◽  
Distribution Networks ◽  
Calculation Model ◽  
Automated System ◽  
Electric Networks ◽  
Steady State Mode ◽  
Power Sources ◽  
Electric Network ◽  
Method Of Calculation

The method of calculation of the steady-state mode of the open city distribution electric network with small generation sources is offered. It is shown that the city electric network consists of passive and active physical elements. Passive elements include power transformers and linear regulators, overhead and cable power lines, current-limiting reactors, etc. Active elements of networks are power sources (transformer inputs of low voltage of feeding substations and distributed small generation sources) and loads, mathematical models of which can be various. Power sources in urban distribution networks of 10 kV and below are classified by type and power and can be of two kinds, viz. power feeding centers of the network and small generation sources. Consumer loads are modeled by current sources connected to network nodes. The parameters of the current sources are usually graphs of the change of the module of the actual current value and the power factor in time. The values of these parameters in single-line substitution schemes of 6–10 kV distribution networks with isolated neutral are assumed to be average for three phases. The power centers are transformer inputs of low voltage power substations of the main electric networks of 35 kV and above, equipped with digital devices of the account of the electric power connected to the automated system of control and accounting of power resources. The developed technique allows receiving the refined balanced calculation model of the steady mode of the open city network for the set time of the daily schedule. It includes the sequential distribution of the specified power of each network power supply between its loads, followed by clarification of flows and power losses in the sections, as well as voltages and actual loads in the nodes of the scheme by the overlay method.

scholarly journals Fabrication of Miniature Components from ZrO2 Powder by Combining Electrical-field Activated Sintering Technique and Micro-forming

2018 ◽  
Vol 190 ◽  
pp. 10007
Author(s):  
Hasan Hijji ◽  
Yi Qin ◽  
Kunlan Haung ◽  
Muhammad Bin Zulkipli ◽  
Jie Zhao
Keyword(s):  
Low Voltage ◽  
Heating Temperature ◽  
Processing Parameters ◽  
Holding Time ◽  
Micro Forming ◽  
High Quality ◽  
Electrical Field ◽  
Activated Sintering ◽  
Zro2 Powder ◽  
Wide Range

There is an increased demand for miniature/micro products (such as MEMS) and nanotechnology-based products (such as nano-materials). Micro-manufacturing is a link between Macro-and Nano Manufacturing and an effective means for transferring nanotechnology-product designs into volume production. The micro forming has the potential for low-cost, high volume manufacturing applications. In order to meet the high demands on miniaturised products, a rapid production technique and the system, high flexibility, cost-effectiveness and processing a wide range of materials are needed. Recently, a series of studies have been undertaken to investigate forming miniature/micro-components by using a combination of micro-forming and Electrical-field activated sintering (Micro-FAST). The process uses low voltage and high current density, pressure-assisted densification and synthesis technique, which renders several significant merits. The work to be reported in this paper will be focused on the forming of miniature components from Zirconia (ZrO2) powder, without using binders. Several processing parameters have been investigated, such as pressure, heating rate, heating temperature and holding time, which helped to obtain high-quality parts. Using graphite dies and punches, sample parts (solid cylinders of Ø4.00mm × 4.00 mm) were formed. These were subjected to detailed examinations and analysis, such as analysis of the relative density, hardness at the necks formed among the particles and in the particle bodies, as well as the microstructures. The results showed that directly forming the parts from loose powder is feasible, and by properly designing and control the processing parameters, high-quality parts could be achieved, among which heating temperature and holding time are extremely important. At the same time, due to low conductivity of the powder material, carefully designing the tooling is essentials for ensuring properly heating, pressurisation and cooling.

scholarly journals Influence of low-voltage electrical switching and protecting devices and parameters of electrical equipment on electricity losses in workshop power supply networks

2021 ◽  
Vol 23 (3) ◽  
pp. 3-13
Author(s):  
E. Yu. Abdullazyanov ◽  
E. I. Gracheva ◽  
A. N. Gorlov ◽  
Z. M. Shakurova ◽  
A. G. Logacheva
Keyword(s):  
Power Supply ◽  
Low Voltage ◽  
Electrical Equipment ◽  
Load Factor ◽  
Equivalent Resistance ◽  
Circuit Breakers ◽  
Supply Networks ◽  
Factors Affecting ◽  
Daily Schedule ◽  
Active Power Losses

THE PURPOSE. To develop an algorithm for estimating electricity losses, taking into account the influencing factors in the main circuits of shop power supply. To study the influence of the main parameters of electrical equipment on the equivalent resistance of the distribution busbar. METHODS. We use element-by-element methods for calculating active power losses using equivalent resistance on the example of a section of the main circuit of the shop network. Factors affecting the equivalent busbar resistance, such as the root-mean-square load factor, the load graph shape factor, the resistance of the contact connections of switching devices, and the ambient temperature, are investigated. RESULTS. The values of the resistances of the branch lines from the busbar are calculated taking into account the heating of the conductors and the resistances of the circuit breakers and magnetic starters installed on the line during the element-by-element calculation. The relations in the value of the equivalent resistance of the busbar to the values of the resistances of the contact connections of low-voltage electrical devices installed on the branch lines from the busbar, the values of the resistances of the branch lines taking into account heating, the value of the resistance of the busbar and the values of the resistance due to the heating of the busbar are revealed. CONCLUSIONS. The share of each of the studied parameters in the value of the equivalent resistance of the busbar is determined. The value of the relative error in determining the equivalent resistance of the busbar depending on the number of connected electric receivers and taking into account the studied parameters is calculated. The estimation of the value of the electricity losses of the section of the main scheme of the shop network was carried out in accordance with the daily schedule of the load of consumers.

scholarly journals Flexible biodegradable transparent heaters based on fractal-like leaf skeletons

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Vipul Sharma ◽  
Anastasia Koivikko ◽  
Kyriacos Yiannacou ◽  
Kimmo Lahtonen ◽  
Veikko Sariola
Keyword(s):  
Surface Temperature ◽  
Surface Area ◽  
Sheet Resistance ◽  
Flexible Electronics ◽  
Low Voltage ◽  
Heating Temperature ◽  
Optical Transmittance ◽  
Ag Nanowires ◽  
Significant Change

Abstract We present a facile method to prepare flexible, transparent, biodegradable, and fast resistive heaters by applying silver (Ag) nanowires onto fractal-like leaf skeletons. The fractal-like structure of the leaf skeleton maximizes its surface area, improving the transfer of heat to its surroundings and thus making the heater fast, without compromising transparency. Ag ion layer on the leaf skeleton helps to conformally cover the surface with Ag nanowires. The sheet resistance of the heater can be controlled by the loading of Ag nanowires, without sacrificing the optical transmittance (~80% at 8 Ω sq−1). The heating is uniform and the surface temperature of a 60 mm × 60 mm heater (8 Ω sq−1) can quickly (5–10 s) raise to 125 °C with a low voltage (6 V). The heater displays excellent mechanical flexibility, showing no significant change in resistance and heating temperature when bent up to curvature of 800 m−1. Finally, we demonstrate the potential of the bioinspired heater as a thermotherapy patch by encapsulating it in a biodegradable tape and mounting it on the human wrist and elbow. This study shows that fractal-like structures from nature can be repurposed as fractal designs for flexible electronics.

scholarly journals Research on the Influence of Distributed Generation on Voltage in Rural Distribution Network

2021 ◽  
Vol 233 ◽  
pp. 01017
Author(s):  
Shen Zeyuan ◽  
Song Wei ◽  
Zhao Haibo ◽  
Li Chunhui ◽  
Shen Zebo ◽  
...  
Keyword(s):  
Power Plant ◽  
Low Voltage ◽  
Distribution Network ◽  
Influence Factors ◽  
Voltage Distribution ◽  
Power Station ◽  
Network Analyses ◽  
Photovoltaic Power ◽  
The One ◽  
Radial Network

With the development of photovoltaic projects for poverty alleviation, large number of distributed photovoltaic power plant is incorporated rural grid. On the one hand, photovoltaic poverty project can increase the income of farmers, on the other hand, it can improve the low voltage problem of rural distribution network. While photovoltaic power plant incorporating makes the distribution network from traditional radial network become active network, and causes a change of voltage distribution in feeder. Rural grid distribution network is the weakest link in the entire grid. So that it is necessary to analyse the influence factors of voltage distribution and the interconnection principles of photovoltaic power station. In this paper, through the modeling and simulation of distributed photovoltaic access to rural distribution network, analyses the law of the capacity and access location of photovoltaic power integration in the distribution network, and summarizes the interconnection requirements of the photovoltaic power station. The results show that only reasonable and proper use the distributed photovoltaic power plant, can play the role of voltage support and solve the problem of low voltage in rural distribution network.

Processing of human melanoma cells for correlative TEM, LVSEM, and LM

1991 ◽  
Vol 49 ◽  
pp. 106-107
Author(s):  
Marek Malecki ◽  
J. Victor Small ◽  
James Pawley
Keyword(s):  
Electron Microscopy ◽  
Low Voltage ◽  
Fluorescent Microscopy ◽  
Blood Stream ◽  
Surface Topology ◽  
Integrin Receptors ◽  
Transmission Electron ◽  
Develop Technology ◽  
Voltage Scanning ◽  
Mechanisms Of Adhesion

The relative roles of adhesion and locomotion in malignancy have yet to be clearly established. In a tumor, subpopulations of cells may be recognized according to their capacity to invade neighbouring tissue,or to enter the blood stream and metastasize. The mechanisms of adhesion and locomotion are themselves tightly linked to the cytoskeletal apparatus and cell surface topology, including expression of integrin receptors. In our studies on melanomas with Fluorescent Microscopy (FM) and Cell Sorter(FACS), we noticed that cells in cultures derived from metastases had more numerous actin bundles, then cells from primary foci. Following this track, we attempted to develop technology allowing to compare ultrastructure of these cells using correlative Transmission Electron Microscopy(TEM) and Low Voltage Scanning Electron Microscopy(LVSEM).

High-pressure freezing of cells in suspension for low-voltage scanning electron microscopy (LVSEM)

1991 ◽  
Vol 49 ◽  
pp. 64-65
Author(s):  
Marek Malecki ◽  
James Pawley ◽  
Hans Ris
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Low Voltage ◽  
Culture Media ◽  
Cell Structure ◽  
Freeze Substitution ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Cell Culture Media ◽  
Voltage Scanning

The ultrastructure of cells suspended in physiological fluids or cell culture media can only be studied if the living processes are stopped while the cells remain in suspension. Attachment of living cells to carrier surfaces to facilitate further processing for electron microscopy produces a rapid reorganization of cell structure eradicating most traces of the structures present when the cells were in suspension. The structure of cells in suspension can be immobilized by either chemical fixation or, much faster, by rapid freezing (cryo-immobilization). The fixation speed is particularly important in studies of cell surface reorganization over time. High pressure freezing provides conditions where specimens up to 500μm thick can be frozen in milliseconds without ice crystal damage. This volume is sufficient for cells to remain in suspension until frozen. However, special procedures are needed to assure that the unattached cells are not lost during subsequent processing for LVSEM or HVEM using freeze-substitution or freeze drying. We recently developed such a procedure.

Development of a conical anode Fe-gun for low voltage SEM

1988 ◽  
Vol 46 ◽  
pp. 978-979
Author(s):  
T. Miyokawa ◽  
S. Norioka ◽  
S. Goto
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Low Voltage ◽  
Irradiation Damage ◽  
Cold Cathode ◽  
Virtual Source ◽  
Source Position ◽  
Electrostatic Lens ◽  
Electrostatic Lenses ◽  
Wide Range

Field emission SEMs (FE-SEMs) are becoming popular due to their high resolution needs. In the field of semiconductor product, it is demanded to use the low accelerating voltage FE-SEM to avoid the electron irradiation damage and the electron charging up on samples. However the accelerating voltage of usual SEM with FE-gun is limited until 1 kV, which is not enough small for the present demands, because the virtual source goes far from the tip in lower accelerating voltages. This virtual source position depends on the shape of the electrostatic lens. So, we investigated several types of electrostatic lenses to be applicable to the lower accelerating voltage. In the result, it is found a field emission gun with a conical anode is effectively applied for a wide range of low accelerating voltages.A field emission gun usually consists of a field emission tip (cold cathode) and the Butler type electrostatic lens.

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