ACCELERATING OF THE ELECTRONS OF ELECTRON BUNCHES IN A WAVEGUIDE LOADED DIELECTRIC STRUCTURE

The paper presents some results of experimental studies of the excitation of wake fields and the acceleration of electrons in waveguide-dielectric structures (DS) upon injection of a sequence of electron bunches into them. Exper-iments have shown an increase in the amplitude of the wake wave and the acceleration of a small fraction of elec-trons when the wavelength of the excited field is equal to the doubled bunch length. A simple physical model of the observed phenomenon is given. Also, the paper proposes a method for accelerating a part of each electron bunch in the steady-state mode of the resonator dielectric structure. Some of the electrons are “cut out” by the collimator and enter the accelerating phase of the previously excited wake wave. The wave is displaced due to the difference in the distances traveled by the wave and the accelerated part of the electrons.

Nonlinear load influence on single-phase fault current in shipboard electric networks

Описаны результаты исследований влияния показателей качества электроэнергии на токи однофазных замыканий в судовых электроустановках. Выявлены основные элементы бортовых электроустановок, влияющие на качество электроэнергии. Проанализировано формирование высших гармоник в токе однофазного замыкания. На физической модели электроустановки проведены исследования влияния нелинейной нагрузки на ток однофазного замыкания. Результаты экспериментов подтвердили установленные закономерности. Выявлено, что в установившемся режиме ток однофазного замыкания определяется не только величиной фазной емкости и напряжением сети, но и несинусоидальностью тока нагрузки. Экспериментально показано, что высшие гармоники, присутствующие в токе нагрузки, усиливаются в токе однофазного замыкания. При этом увеличение их амплитуд пропорционально номеру гармоники и ее амплитуде в токе нагрузки. Экспериментально установлено, что формирование высших гармоник в токе однофазного замыкания в результате эмиссии нелинейной нагрузкой приводит к увеличению его действующего значения. The paper represents the research results of the power quality indicators influence on the currents of single-phase ground faults in ship electrical installations. The main elements of on-board electrical installations that affect the quality of electricity are identified. The process of higher harmonics formation in the single-phase ground fault current is analyzed. Studies of the nonlinear load influence on the single-phase fault current are carried out on the physical model of the electrical installation. The experimental results confirmed the established patterns. For the steady-state mode it was discovered that the single-phase ground fault current is determined not only by the phase capacitance value and the mains voltage, but also by the non-sinusoidality of the load current. It has been shown experimentally that the higher harmonics of the load current are amplified in the single-phase ground fault current. In this case, the increase at their amplitudes is proportional to the harmonic number and its amplitude in the load current. It has been experimentally established that the formation of higher harmonics at a single-phase ground fault current as a result of emission by a nonlinear load leads to an increase in its effective value.

Modeling of automatic control system for air supply to a bio-reactor using fuzzy control

The stages of modeling the automatic control system (ACS) for air supply to aeration with the use of fuzzy control are considered. The investigated control algorithm is based on the combination of a nonlinear controller with approximating control (CAC), whose parameters are corrected using fuzzy logic. The algorithm for correcting the CAC parameters for transient and steady state modes is based on the application of two simple rulebases (RB) with three and five linguistic terms, respectively. As a result, the required speed in the transient mode and accuracy in the steady state mode are provided. It is proved that switching the RB according to the logic of the multi-mode system is less demanding on the number of rules, structure and setting parameters of the membership function than using the extended RB. The differences between the proposed ACS with different BP for the main operating modes of the system are shown. These include: improvement of quality indicators due to the implementation of different BP in different modes; more rigorous justification of the mechanism for ensuring insensitivity to the switching moments of BP when changing modes due to the CAC of the direct circuit of the ACS. Effective implementation of the stages of ACS modeling and fuzzy controller design is possible using the Fuzzy Logic Toolbox system of the Simulink MATLAB modeling environment.

Method of Switching on and Off a Power Transformer with a Capacitor Bank in an Electrothermal Installation

The article is devoted to issues related to increasing the energy efficiency of industrial electrothermal installations, both in starting and stationary operating modes due to the use of capacitors and thyristor starters with special control. The results of a significant reduction in the duration of the transient process, elimination of surges and asymmetry of starting currents and voltage drawdowns are presented. The results of full compensation of the reactive power of the network in the steady-state mode are also presented. It is shown that the starting currents do not exceed their steady-state values and that the shutdown of the electrothermal installation is performed without the occurrence of an arc and switching losses at the contacts of the switches. Researches of an electrothermal installation with a capacity of 750 kV⋅A and a voltage of 380 / 80 V are made on the model in the Matlab environment.

Voltage Stability Evaluation in the Nigeria 44 Bus Grid Network using Modal Analysis

This paper focused on the application of modal analysis method to determine the voltage stability of the Nigeria 44 bus 330kV transmission grid network and to determine the network’s weakest buses. Modal method calculates the smallest eigenvalue and all the associated eigenvectors of the reduced Jacobian matrix, JR using steady state mode. The network model was developed in PSAT-MATLAB and load flow was performed on the network. Results and analysis showed that the Nigeria 44 Bus grid network was found to be unstable as the modal analysis revealed the presence of eigenvalue with a negative real part. Gombe, Damaturu and Yola buses were also discovered to be the vulnerable buses since their voltage profile fell below the IEEE standard voltage level of (0.95-1.05) pu. Yola bus was spotted as the weakest bus based on the analysis of the participating factors.

Monitoring and Detection of Vehicle Emissions on Steady State Mode using Internet of Things

This project is to develop a compact system to identify and display pollutants in a vehicle. The level of emissions can be monitored and inspected by this system. Database of each vehicle emissions test can be recorded and the report can be obtained to create an awareness to the drivers and owners about the pollution caused by the vehicle. An IoT (Internet of Things) based air pollution observing framework incorporated a MQ series sensor interfaced to a node MCU set with an ESP8266 WLAN connector to send the sensor reading to an Ubidots cloud. This outline is used for noticing pollutions in demeanour of specific territory and to get the air peculiarity or property examination. The obligated framework will focus on checking the air pollutants concentration with the help of a mixture of internet of things with wireless sensor systems. The investigation of emissions should be possible by figuring out the air quality index (AQI).

One-step coupled calculations (Serpent-OpenFOAM) for a fuel rod of the IPR-R1 triga reactor

In this work, a single step of coupled calculations for a fuel rod of IPR-R1 TRIGA was performed. The used me-thodology allowed to simulate the fuel pin behavior in steady-state mode for different power levels. The aim of this paper is to present a practical approach to perform coupled calculations between neutronic (Monte Carlo) and thermal-hydraulic (CFD) codes. For this purpose, is necessary to evaluate the influence of the water thermal-physical properties temperature variations on keff parameter. Besides that, Serpent Nuclear Code was used for the neutronics evaluation, while OpenFOAM was used for thermal-hydraulics. OpenFOAM si- mula-tions were made by using a modified chtMultiRegionFoam solver, developed to read Serpent output correctly. The neutronic code was used without any modifications. The results shows that this coupled calculations were consistent and that leads to encouraging further methodology development and its use for full core simulation. Also, the results shows good agreement with calculations performed using other version of OpenFOAM and Milonga as neutronic code.

Evaluating the impact of Khanh Son power plant on Danang Distribution Network

Today, the expansion of power sources is the main task to meet the development of demand. Therefore, Da Nang City has been approved to build the Khanh Son waste incineration power plant in the near future. The Khanh Son power plant project not only helps to reduce a large amount of waste in the area but also provides electricity supply directly to the city, increasing the budget for that locality. However, the connection of this power plant to the system will modify the operating parameters of the grid which may cause some negative impact on the regional power system. Therefore, the main aim of this paper is to simulate various operation modes of the system such as steady-state mode, short circuits, and transient to evaluate the impact of the connection of the new power plant on the national power. The result shows that the Khanh Son power plant helps to reduce the overload of the main cable during the high load scenario, the stability of the system is enhanced significantly. Based on the simulation results, some recommendations to ensure the stabilizing of the grid have been proposed as well.

Autothermal Reforming of Diesel Oil for PdCeCrFeCu/Al2O3-Catalyzed Hydrogen Production

Zero-dimensional two-stage SOFC stacks dynamic model was developed to investigate the effect of operating parameters on stacks performance. The model resolves spatially thermal and thermo-electrochemical behaviour for electrochemical reactions, Catalytic Partial Oxidation and Steam Reforming processes. Design variables and thermo-electrochemical properties were obtained from in-house-fabricated SOFCs carried out by project partners. The completed SOFCs based Combined Heat and Power, CHP, system model was validated by data18 and numerical results obtained at steady-state mode showing its high-fidelity. A parametric study with respect to key operating parameters including changes in fuel utilization, lambda number and current density values was conducted. The global CHP system dynamic response, in term of the current/voltage delivered by two-stage SOFC stacks, under a fixed fuel utilization, has been determined resulting in greater variations in the voltage of a single cell in the first stack in comparison to the corresponding values in the second stack.

A mathematical model of two-stage Solid Oxide Fuel Cell, SOFC, stacks for dynamic simulation of Combined Heat and Power system fed by natural gas

Zero-dimensional two-stage SOFC stacks dynamic model was developed to investigate the effect of operating parameters on stacks performance. The model resolves spatially thermal and thermo-electrochemical behaviour for electrochemical reactions, Catalytic Partial Oxidation and Steam Reforming processes. Design variables and thermo-electrochemical properties were obtained from in-house-fabricated SOFCs carried out by project partners. The completed SOFCs based Combined Heat and Power, CHP, system model was validated by data18 and numerical results obtained at steady-state mode showing its high-fidelity. A parametric study with respect to key operating parameters including changes in fuel utilization, lambda number and current density values was conducted. The global CHP system dynamic response, in term of the current/voltage delivered by two-stage SOFC stacks, under a fixed fuel utilization, has been determined resulting in greater variations in the voltage of a single cell in the first stack in comparison to the corresponding values in the second stack.