scholarly journals A differential operation principle of the automatic bus transfer system pickup unit as a way of decreasing the emergency clearing time.a

2022 ◽  
Vol 1211 (1) ◽  
pp. 012009
Author(s):  
Nikolay Danilov ◽  
Sergey Tsyruk ◽  
Alexandr Timonin ◽  
Karam Sharafeddine
Keyword(s):  
Power Supply ◽  
High Speed ◽  
Short Circuit ◽  
Open Circuit ◽  
Synchronous Motors ◽  
New Device ◽  
Study Results ◽  
Automatic Bus Transfer ◽  
Operation Algorithm ◽  
Emergency Events

Abstract A proper choice of the design and operation algorithm of emergency control devices like high-speed bus transfer (HSBT) is only possible proceeding from a study and analysis of steady-state and transient processes in emergency modes of operation (short-circuit faults, power supply disconnection, or phase open-circuit fault). The numerical experiments for studying such modes that were carried out, using the Matlab Simulink software package, on the mathematical models of an industrial power supply system involving synchronous motors connected to it made it possible to synthesize a new differential HSBT pickup unit featuring a high-speed response to emergency events. In doing so, special attention was paid to an analysis of transient operation modes with the aim of minimizing the probability of false actuations. The obtained study results have found practical application in the HSBT devices installed at the facilities of PJSC MOSENERGO. The experience gained from the operation of a new device jointly with high-speed circuit breakers produced by the Tavrida-Elektrik state-owned corporation has demonstrated essential advantages in comparison with the conventional HSBT designs.

Fluttering Amplitude Amplification by Utilizing Flapping Moment in Flutter-Driven Triboelectric Nanogenerator

2021 ◽  
Author(s):  
Yi Zhang ◽  
Ka Chung Chan ◽  
Sau Chung Fu ◽  
Christopher Yu Hang Chao
Keyword(s):  
Flow Velocity ◽  
High Speed ◽  
Aerodynamic Force ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Energy Output ◽  
Small Scale ◽  
Triboelectric Nanogenerator ◽  
Peak Value

Abstract Flutter-driven triboelectric nanogenerator (FTENG) is one of the most promising methods to harvest small-scale wind energy. Wind causes self-fluttering motion of a flag in the FTENG to generate electricity by contact electrification. A lot of studies have been conducted to enhance the energy output by increasing the surface charge density of the flag, but only a few researches tried to increase the converting efficiency by enlarging the flapping motion. In this study, we show that by simply replacing the rigid flagpole in the FTENG with a flexible flagpole, the energy conversion efficiency is augmented and the energy output is enhanced. It is found that when the flag flutters, the flagpole also undergoes aerodynamic force. The lift force generated from the fluttering flag applies a periodic rotational moment on the flagpole, and causes the flagpole to vibrate. The vibration of the flagpole, in turn amplifies the flutter of the flag. Both the fluttering dynamics of the flags with rigid and flexible flagpoles have been recorded by a high-speed camera. When the flag was held by a flexible flagpole, the fluttering amplitude and the contact area between the flag and electrode plates were increased. The energy enhancement increased as the flow velocity increased and the enhancement can be 113 times when the wind velocity is 10 m/s. The thickness of the flagpole was investigated. An optimal output of open-circuit voltage reaching 1128 V (peak-to-peak value) or 312.40 V (RMS value), and short-circuit current reaching 127.67 μA (peak-to-peak value) or 31.99 μA (RMS value) at 12.21 m/s flow velocity was achieved. This research presents a simple design to enhance the output performance of an FTENG by amplifying the fluttering amplitude. Based on the performance obtained in this study, the improved FTENG has the potential to apply in a smart city for driving electronic devices as a power source for IoT applications.

scholarly journals Mil-Std 1553 Cable Modeling for Fault Detection

2020 ◽  
Vol 9 (4) ◽  
pp. 1648-1655
Keyword(s):  
Fault Detection ◽  
Public Transportation ◽  
High Speed ◽  
Power Transmission ◽  
Detection System ◽  
Short Circuit ◽  
Detection Algorithm ◽  
Open Circuit ◽  
Test Signal ◽  
Prototype Development

Amongst major industries, the aircraft industry has gained momentum not only in public transportation, but also in defence, business and space sectors. The electrical, mechanical and electronic systems of an aircraft are all interconnected by different types of cables like hook up wires, cables for high speed data transmission, cables for power transmission, fire resistant cables, co-axial cables etc , with each type of cable having its own specifications. Military Standard 1553 (Mil-Std 1553) is one such cable primarily used for on-board aircraft sub-system communication and monitoring. Mil-Std 1553 protocol defines the physical and electrical properties of the cable. Mil-Std 1553 is a dual redundant bus, that is, there are two channels for a single bus communication. Mil-Std 1553 is prone to faults like opens or shorts because of its continuous wear and tear in aircraft environment. If a faulty cable is operated, then it possesses a high risk to the aircraft system .As of now ,there is no automatic fault detection system employed on Mil-Std 1553. Hence there is a need for automatic fault detection system on Mil-Std 1553 cables before the entire system collapses. In this regard, modeling of Mil-Std 1553 is very important since the developed model can be used for testing of the fault detection algorithm and further prototype development. Here, the Mil-Std 1553 cable has been modeled using SIMULINK/MATLAB. The cable is modeled under two different scenarios: considering only the Test Signal , considering both Test Signal and Data Signal. The cable is modeled considering all its electrical characteristics for three conditions, namely, No Fault condition, Open circuit condition and Short circuit condition. PI section is used as an elemental block for modeling of Mil-Std 1553.

Design of Flow Adjusting Device in Diffuser of Open-Circuit Wind Tunnel with Low Speed Based on CFX

2015 ◽  
Vol 799-800 ◽  
pp. 640-644
Author(s):  
Xiao Yi Wang ◽  
Chong Gao ◽  
Fu Qiang Chen ◽  
Yu Hua Zhang ◽  
Zhi Zhen Qiu
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
High Speed ◽  
Reference Frames ◽  
Open Circuit ◽  
Analysis Model ◽  
Low Speed ◽  
Guide Plate ◽  
Study Results ◽  
Field Quality

The diffuser in wind tunnel plays a vital role to improve flow field quality. Many flow adjusting devices in diffuser were studied by lots of researchers in the world to inhibit flow separation. However, most of them were applied on closed-circuit wind tunnel with high speed. It is necessary to design appropriate flow adjusting device for diffuser in open-circuit wind tunnel with low speed which was increasingly used in aerodynamic experiment. The structure of a new open-circuit wind tunnel with low speed was firstly introduced in this paper. The flow adjusting device was designed, which was composed of three parts, namely contracting cone, air guide plate and screen. On the basis of analysis model for diffuser, the influences of contracting cone, air guide plate and screen on flow field quality were respectively given by CFX simulation that was using multiple reference frames and RNG k-ε turbulence model. Case study showed that the role of single part was limited, combined effect of three parts in flow adjusting device could greatly improve quality of flow field in diffuser. The study results mentioned above are useful for designing flow adjusting device in diffuser of practical open-circuit wind tunnel with low speed.

scholarly journals Optimizing and Implementing the Switching of Motor Loads to Backup Power

2021 ◽  
Vol 21 (1) ◽  
pp. 68-74
Keyword(s):  
Mathematical Modeling ◽  
Power Supply ◽  
High Speed ◽  
Short Term ◽  
Residual Voltage ◽  
Synchronous Motors ◽  
Electromagnetic Moments ◽  
Asynchronous Motors ◽  
The Subject ◽  
Bench Testing

Current and electromagnetic moments of synchronous and asynchronous motors need to be below the star­ting values when such motors are self-starting after triggering a high-speed automatic transfer switch; this is the subject matter of this paper. A mathematical model is applied herein to find the range of permissible angle of backup power fed to asynchronous and synchronous motors exposed to short-term power deviations; the range is a function of the angle between the residual voltage of the main power supply and the voltage of the backup. The paper further proposes methods of switching to backup power that keep the currents and electromagnetic moments of self-starting motors below the starting values; these methods can be implemented in high-speed automatic transfer switch (ATS) microprocessors. Bench testing and mathematical modeling prove the proposed methods effective.

Multiphase High-Frequency Isolated DC–DC Converter for Industrial Applications

2014 ◽  
Vol 15 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Rakesh Maurya ◽  
S. P. Srivastava ◽  
Pramod Agarwal
Keyword(s):  
Power Supply ◽  
High Frequency ◽  
Control Method ◽  
Low Voltage ◽  
Short Circuit ◽  
Welding Process ◽  
Industrial Applications ◽  
Open Circuit ◽  
Operating Conditions ◽  
Prototype Model

Abstract Industrial applications such as welding, plasma cutting, and surface hardening require a large DC current at low voltage. In such applications, the rating of power supply varies from few kilowatts to hundreds of kilowatts. The power supply employs in such applications particularly in arc welding process is expected to operate from open-circuit (no-load) to short-circuit (when the electrode sticks to the workpiece for a short span of time) quickly. In this paper, high-frequency isolated multiphase DC–DC converter is proposed which is well suited for aforementioned applications. Based on mathematical analysis, a simulation study with 5 kW, 5 V/1,000 A proposed model is carried out using Simulink block set and Sim Power System tool box and its performances are evaluated under symmetrical control methods. To verify the simulation results, scaled prototype model of rating 1.5 V/100 A is developed and tested with aforementioned control method under different operating conditions. In comparison with conventional welding power supply employed in many industries, the performance of proposed converter is improved significantly in terms of size and weight, efficiency and dynamic response.

Calculation of Short-Circuit Fault Currents in an Electric Traction Network with Double Ended Power Supply

2019 ◽  
Vol 5 (5) ◽  
pp. 19-23
Author(s):  
Leonid A. GERMAN ◽  
◽  
Alexandr S. SEREBRYAKOV ◽  
Aleksey B. LOSKUTOV ◽  
Vladimir L. OSOKIN ◽  
...  
Keyword(s):  
Power Supply ◽  
Short Circuit ◽  
Fault Currents ◽  
Traction Network ◽  
Electric Traction ◽  
Short Circuit Fault

Lock-in Thermography-Based Local Efficiency Analysis of Solar Cells

2012 ◽  
Author(s):  
Otwin Breitenstein
Keyword(s):  
Solar Cells ◽  
Short Circuit ◽  
Efficiency Analysis ◽  
Open Circuit ◽  
Local Defect ◽  
Whole Cell ◽  
Local Efficiency ◽  
Cell Efficiency ◽  
Lock In ◽  
Efficiency Data

Abstract The electronic properties of solar cells, particularly multicrystalline silicon-based ones, are distributed spatially inhomogeneous, where regions of poor quality may degrade the performance of the whole cell. These inhomogeneities mostly affect the dark current-voltage (I-V) characteristic, which decisively affects the efficiency. Since the grid distributes the local voltage homogeneously across the cell and leads to lateral balancing currents, local light beam-induced current methods alone cannot be used to image local cell efficiency parameters. Lock-in thermography (LIT) is the method of choice for imaging inhomogeneities of the dark I-V characteristic. This contribution introduces a novel method for evaluating a number of LIT images taken at different applied biases. By pixel-wise fitting the data to a two diode model and taking into account local series resistance and short circuit current density data, realistically simulated images of the other cell efficiency parameters (open circuit voltage, fill factor, and efficiency) are obtained. Moreover, simulated local and global dark and illuminated I-V characteristics are obtained, also for various illumination intensities. These local efficiency data are expectation values, which would hold if a homogeneous solar cell had the properties of the selected region of the inhomogeneous cell. Alternatively, also local efficiency data holding for the cell working at its own maximum power point may be generated. The amount of degradation of different cell efficiency parameters in some local defect positions is an indication how dangerous these defects are for degrading this parameter of the whole cell. The method allows to virtually 'cut out' certain defects for checking their influence on the global characteristics. Thus, by applying this method, a detailed local efficiency analysis of locally inhomogeneous solar cells is possible. It can be reliably predicted how a cell would improve if certain defects could be avoided. This method is implemented in a software code, which is available.

Ensuring electrical safety of power supply systems of electrified AC railways for highspeed lines

2018 ◽  
Vol 77 (6) ◽  
pp. 337-346 ◽  
Author(s):  
A. B. Kosarev ◽  
A. V. Barch ◽  
E. N. Rozenberg
Keyword(s):  
Power Supply ◽  
High Speed ◽  
Structural Features ◽  
Electrical Safety ◽  
Safe Operation ◽  
Ballastless Track ◽  
Conventional Structure ◽  
Artificial Earth ◽  
Earth Connection ◽  
Supply Systems

Abstract. High-speed railways are fast-growing and promising type of traffic. In Russia development of high-speed railway service is associated with the solution of a number of problems, including infrastructure. Authors propose to use earth connection of the railway catenary with the help of an artificial earthing switch on currently designed high-speed line Moscow—Kazan for 2×25 kV power supply system. Taking into account requirements for electrical safety conditions for maintenance of the track and earthed catenary supports, paper justifies method for calculating allowable voltages of rail—earth points and supports of catenary. Methods takes into account structural features of ballastless track superstructure used for high-speed lines. It is estimated that the voltages admissible under the electrical safety conditions are random in nature and distributed logarithmically normal. When calculating probability of safe operation, one should take into account random nature of both permissible stresses and those actually occurring on the track. It is estimated that the probability of safe operation in traction networks of sections with ballastless track superstructure does not exceed a similar value in electrified sections with the conventional structure of a ballast prism. Feasibility of using a 2×25 kV earth system using an artificial earth connection is confirmed, recommendations on its use are given. Authors substantiate allowable values of the rail—earth voltage and catenary supports, which practically exclude the occurrence of hazardous situations for personnel maintaining the track in sections with ballastless track superstructure.

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