Moshe Averbukh - Academia.edu (original) (raw)

Papers by Moshe Averbukh

Machines, Dec 8, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Electronics, Mar 24, 2019

Widespread use of photovoltaic (PV) small and middle-power plants close or inside existing townsh... more Widespread use of photovoltaic (PV) small and middle-power plants close or inside existing townships and villages may cause significant deviations of the grid voltage. Owing to the oscillation of solar irradiation and corresponding power flows these voltage instabilities can damage equipment and must be prevented. Designated for the voltage regulation tap-changers in distribution transformers located in a significant distance of such settlements have a sluggish response time. As a possible answer for their delay is the smoothing energy of flows in PV power installation by intermittent capacitor low-pass filtering (LPF) located near those PV facilities. The application of ultracapacitors (UC) for LPF is remarkable due to their sustainability and relatively low costs of energy storage. The parameters selection of such appliances is a well-designed procedure for linear circuits. However, DC-AC inverters in PV facilities are represented by a power (instead of a voltage) source. As a result, the total circuit including such LPF becomes a non-linear and its transient process and consequently, its efficiency is difficult to assess requiring each time of development the UC storage an application complex numerical procedure. Engineers are usual to work with linear circuits that are describing fine by a time constant is designated as a multiplication of a capacitance times load equivalent resistance. In the case of PV DC-AC inverters, such an approach can be applied as well but a value of a time constant should be corrected. Considering a significant cost of UC storage, the non-optimal selection of a correcting coefficient may cause considerable loses. Submitted in the presented article is an original approximation procedure giving an efficiently approachable technique to select correcting coefficient for describing non-linear dynamic process by its linear analog. This way the development low-pass UC filtering in electrical systems with PV plants becomes more efficient and simpler task.

Micro-grid power system becomes today vital reality for many of energy applications including rem... more Micro-grid power system becomes today vital reality for many of energy applications including remote habitations areas, military bases, and retranslation and communication equipment and so on. One on the central problem during developments of such systems represents the pressing need to optimize a) the structural design of all facilities including renewable sources (solar), controllable sources (diesel-generator), electrical storage (batteries) and b) control of energy flows inside a system providing optimal efficiency and minimum of fossil fuel consumption. Present works provides the simulation modeling of entire micro-grid system having various parameters of all system components. The special accent was made on the simulation of electrical power consumption models, which was developed taking into account significantly stochastic behavior of energy demands. Simulation modeling was realized by the application of MATLAB/Simulink program software. Stochastic models of energy demands and solar energy possibilities were developed on the base of real data were registered during prolonged period of time in the Negev region of Israel.

Energies, Sep 4, 2020

The specific power storage capabilities of double-layer ultracapacitors are receiving significant... more The specific power storage capabilities of double-layer ultracapacitors are receiving significant attention from engineers and scientific researchers. Nevertheless, their dynamic behavior should be studied to improve the performance and for efficient applications in electrical devices. This article presents an infinite resistor-capacitor (r-C) chain-based mathematical model for the analysis of double layer ultracapacitors. The internal resistance and capacitance were measured for repetitive charging and discharging cycles. The magnitudes of internal resistance and capacitance showed approximately ±10% changes for charge-discharge processes. Electrochemical impedance spectroscopy investigations revealed that the impedance of a double-layer ultracapacitor does not change significantly in the temperature range of (−30 • C to +30 • C) and voltage range of (0.3376-2.736 V). The analysis of impedance data using the proposed mathematical model showed good agreement between the experimental and theoretical data. The dynamic behavior of the ultracapacitor was successfully represented by utilizing the proposed infinite r-C chains equivalent circuit, and the reverse Fourier transform analysis. The r-C electrical equivalent circuit was also analyzed using the PSIM simulation software to study the dynamic behavior of ultracapacitor parameters. The simulation study yields an excellent agreement between the experimental and calculated voltage characteristics for repetitive charging-discharging processes.

International Journal of Energy Research, Mar 21, 2019

In this study, we propose an efficient design for a portable energy generator using a parallel-pl... more In this study, we propose an efficient design for a portable energy generator using a parallel-plate capacitor. Analytical calculations show that if charge (Q) is kept constant and dielectric subsequently removed from the capacitor, then electrostatic energy increases by a factor of ε r (permittivity). Initially, a priming charge must be loaded onto the capacitors that are subsequently disconnected from the voltage source. A significant mechanical nonlinear force is needed to remove the dielectric slab. In the proposed configuration, dielectric constitutes the rotor of generator and is located between two pairs of conducting disks, which constitute the stator. The rotor is divided into four dielectric sectors at 60°spacing whereas the stator is divided into six conducting sectors at 30°spacing. In each cycle, two dielectric slabs go inside the capacitor and two other come outside. This specific geometrical arrangement diminishes the extent of mechanical forces and helps to enhance the efficiency of generator significantly. Additionally, this work also relates to generating large amplitude of voltage that can be used as a high voltage source.

Energies, Apr 26, 2022

An application of magnetic amplifiers that were frequently used in the past, still appears in pow... more An application of magnetic amplifiers that were frequently used in the past, still appears in power systems. Despite distinguished benefits of semiconductor electronics, some important advantages of the magnetic amplifier (MA) such as noticeable reliability and sustainability, provide its applications in power control till now. The basic principle of MA is based on a nonlinearity of magnetization curve leading to the effect of saturation in the magnetic circuit. AC coils which are wound on such a core depending on the operating point location may have significantly different impedance one that can provide regulating of power flow. The regulating process is ensured by an additional DC coil which can change working point by controlling DC current flowing through.The common problem of MA operation is inducing in a DC coil of electromotive force (EMF) led by an AC current flowing in the AC winding. This impact creates substantial obstacles in DC current control and should be diminished as much as possible.Several solutions are applicable to resolve this complication among which stands out the use of magnetic coils with perpendicular magnetic fields.In this article presented specially developed perpendicular coils design one inside and another outside novel toroidal magnetic core made thin ferromagnetic ribbon with high ferromagnetic permeability. These windings owing original core design and good ferromagnetic properties can provide substantial amplification coefficient of MA.Two frameworks of magnetic core are investigated in this article. One is made like a serpentine continuously winded ribbon. The other is represented by separated sections of ribbons that wound and then fixed by means of micro-welding. Ribbon segments touching each other with their edges and wound in several layers, the upper layers above the lower ones thus, to close air gaps between the lower lying sections.The investigation results of both these designs are presented in this article.

Electrical storage components such as ultracapacitors (UC) attract enlarged regard in different i... more Electrical storage components such as ultracapacitors (UC) attract enlarged regard in different industry sectors from electric vehicles up to renewable power plants. Among existing storage technologies stand out asymmetric Li-ion hybrid and symmetric double-layer UC. Both devices able to provide prominent charge/discharge current together with extremely prolonged service life. However, Li-ion UC have twofold higher energy density and service life compared to that of conventional double-layer UC. Whereas a double-layer capacitor (DLUC) ensure four-six times lower internal resistance and more stable capacitance which isn’t dependent on UC voltage. This guarantee more stable functionality and higher charge-discharge current.The developer of storage facilities to provide an optimal design should know mentioned above electrical properties of UC.Considering relative novelty of these storage technologies (Li-ion UC is manufactured 6-7 years only, DLUC sim15\sim15sim15 years) two major parameters (internal resistance and capacitance) and their comparison aren’t yet determined for a full range of their applicability.Considering this fact, the current article represents preliminary results of UC dynamic properties. In fact, they are internal resistance and capacitance testing of UC CPQ2300S (2300F, 2.2-3.8V, JSR Co.) and of BCAP3400 (3400F, 2.85V, Maxwell Technologies Co.). As these parameters are significantly changing with current, voltage and capacitor temperature following ranges were chosen: current 20-100A, and a voltage-due to the permissible range.

Scientific Reports, Jul 10, 2023

One of the greatest challenges for widespread utilization of solar energy is the low conversion e... more One of the greatest challenges for widespread utilization of solar energy is the low conversion efficiency, motivating the needs of developing more innovative approaches to improve the design of solar energy conversion equipment. Solar cell is the fundamental component of a photovoltaic (PV) system. Solar cell's precise modelling and estimation of its parameters are of paramount importance for the simulation, design, and control of PV system to achieve optimal performances. It is nontrivial to estimate the unknown parameters of solar cell due to the nonlinearity and multimodality of search space. Conventional optimization methods tend to suffer from numerous drawbacks such as a tendency to be trapped in some local optima when solving this challenging problem. This paper aims to investigate the performance of eight state-of-the-art metaheuristic algorithms (MAs) to solve the solar cell parameter estimation problem on four case studies constituting of four different types of PV systems: R.T.C. France solar cell, LSM20 PV module, Solarex MSX-60 PV module, and SS2018P PV module. These four cell/modules are built using different technologies. The simulation results clearly indicate that the Coot-Bird Optimization technique obtains the minimum RMSE values of 1.0264E-05 and 1.8694E−03 for the R.T.C. France solar cell and the LSM20 PV module, respectively, while the wild horse optimizer outperforms in the case of the Solarex MSX-60 and SS2018 PV modules and gives the lowest value of RMSE as 2.6961E−03 and 4.7571E−05, respectively. Furthermore, the performances of all eight selected MAs are assessed by employing two non-parametric tests known as Friedman ranking and Wilcoxon rank-sum test. A full description is also provided, enabling the readers to understand the capability of each selected MA in improving the solar cell modelling that can enhance its energy conversion efficiency. Referring to the results obtained, some thoughts and suggestions for further improvements are provided in the conclusion section.

Applied sciences, Sep 26, 2019

Electro-conductive carbon felt (CF) material is composed by bonding together different lengths of... more Electro-conductive carbon felt (CF) material is composed by bonding together different lengths of carbon filaments resulting in a porous structure with a significant internal surface that facilitates enhanced electrochemical reactions. Owing to its excellent electrical properties, CF is found in numerous electrochemical applications, such as electrodes in redox flow batteries, fuel cells, and electrochemical desalination apparatus. CF electro-conductivity mostly arises from the close contact between the surface of two electrodes and the long carbon fibers located between them. Electrical conductivity can be improved by a moderate pressing of the CF between conducting electrodes. There exist large amounts of experimental data regarding CF electro-conductivity. However, there is a lack of analytical theoretical models explaining the CF electrical characteristics and the effects of compression. Moreover, CF electrodes in electrochemical cells are immersed in different electrolytes that affect the interconnections of fibers and their contacts with electrodes, which in turn influence conductivity. In this paper, we investigated both the role of CF compression, as well as the impact of electrolyte characteristics on electro-conductivity. The article presents results of measurements, mathematical analysis of CF electrical properties, and a theoretical analytical explanation of the CF electrical conductivity which was done by a stochastic description of carbon filaments disposition inside a CF frame.

Sensors, Feb 13, 2023

The use of low-pass filters for smoothing energy flows in different applications is remarkable. H... more The use of low-pass filters for smoothing energy flows in different applications is remarkable. However, in the case of a power (instead of a voltage) source, this circuit becomes non-linear and its transient process is difficult to assess. Such cases are typical for renewable (PV and wind turbine) plants being equipped with DC-AC power converters.Submitted in the presented article is an approximation procedure, which gives a linearization and an efficiently approachable technique to compare real current (voltage) curves with estimated results. As a result, the development of low-pass filter fed by power source becomes relatively simple task.

Energies, Nov 23, 2022

Simulation, Sep 26, 2012

An approach allowing the creation of parameter uncertainties and external disturbances without an... more An approach allowing the creation of parameter uncertainties and external disturbances without any hardware parts supplementary to the nominal system is proposed in this manuscript. The emulating signal, reflecting the plant variations, essential for testing of controllers, is created in software and added to the plant input, forcing the nominal system output to resemble the output of a system with actual uncertainties and disturbances, thus allowing us to test the controller’s robustness prior to an actual field test. In addition, the full state vector of the emulated system may be reconstructed and fed back to the controller, if necessary. The proposed methods allow simultaneous emulation of any combination of time-varying parameter variations and external disturbances. The method can be related to a class of enhanced hardware-in-the-loop simulations, since the nominal hardware is present in the setup in addition to the controller under test. The proposed techniques can be used to test the performance of advanced control algorithms before their mass production. Extended simulation results are reported to confirm the feasibility of the proposed approaches.

Electronics, Jan 28, 2021

Materials, Jul 5, 2023

Electrification of Israel railroads is a successful project being realized during present time. A... more Electrification of Israel railroads is a successful project being realized during present time. Among the well-known advantages of electric train exploitation are high energetic efficiency, regenerative breaking, diminished pollution, flexibility of traffic control and improved transportation dynamics. However, the use of electric train is accompanied with some specific hurdles caused by significantly stochastic power flows. While in transit between stations an electric train has different phases of movement, during some consuming energy, but from time to time throughout braking processes they become generators transmitting energy back into the electric grid. This circumstance may produce voltage instability in distribution lines, which should be kept inside permissible limits to allow normal operation of electric equipment. Tap-changers on distribution transformers considered for a voltage regulation have sluggish response of ~7-8 sec. Therefore, fast changes of power stream can cause significant voltage deviations. If the voltage overcome explicit allowable level a trigger of a protection system is engendered disconnecting vehicles from a grid. The last causes extremely dangerous detriments and should be maximally prevented.Rapid and considerable changes in train power consumption, in addition may cause network frequency instability which in turn can violate electricity supply.Present article provides an original examination of the future stability of network frequency and distribution voltage which may be assumed when 420 km of Israel railroads will be electrified in the following 5–10 years. For such study special algorithm based on simulation approach was developed and applied. Predicting scenarios for frequency and distribution lines voltage control are represented below in the following text.

European Conference on Power Electronics and Applications, Sep 1, 2018

Local and distributed PV solar plants become more and more widespread power generating facilities... more Local and distributed PV solar plants become more and more widespread power generating facilities providing significant percentage of electricity supply. Together with numerous advantages massive rooftop PV installations (up to 5–10 kW) and utility-scale local plants of 5–20 MW in the low (LV) and middle (MV) voltage distribution networks produce a problem for voltage regulation. Rapid deviations in PV power inherent in this type of energy generate uncertainty in voltage control. Tap changers which are applicable to this purpose have sluggish reaction and occasionally couldn't be able to compensate fast changings of solar electricity. Together with the fluctuations of the consumer's power demands such disturbances can cause dangerous voltage instabilities. As a result, the protection system should disconnect PV stations from electricity supply what negatively affects electricity costs and reliability of the network. One of the possible solutions for mitigation voltage deviations is intermittent energy storage based on ultracapacitors (UC) usage. UC application can improve the voltage stability hence increasing complexity of energy equipment and energy costs. Therefore, the selection of UC bank should be done suitably considering technical and economic aspects of the problem. Current work represents a solution for improving the situation with local voltage regulation based on the appropriate selection of UC bank.

District heating networks are commonly addressed in the literature as one of the most effective s... more District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand-outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations.

The correct selection of appropriate induction motor for a specific electric drive represents an ... more The correct selection of appropriate induction motor for a specific electric drive represents an important issue, especially when VFD is applied for the motor supply. A number of different approaches were suggested for this aim. Methods of motors selection that founded on assessment and minimization of energy losses in the motor are preferable, since they provide optimal selection of a motor with a prolonged service time and maximum energy efficiency. There are three different kinds of losses in the motor: cooper resistive losses, mechanical and iron (core) losses. The present work describes the approach of iron losses estimation for a VFD FC51 of Danfoss Company. The method is based on the representation of supplied voltage (current) by the Fourier Transform and analytical description of iron losses by interpolation polynomials.