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Acceleration of exit to steady-state mode when modeling semiconductor converters
(Національний технічний університет "Харківський політехнічний інститут", 2023) Yagup, V. G.; Yagup, K. V.
The purpose of the article is to develop a method and algorithm for the accelerated calculation of steady states of thyristor converters using computer models of converters based on the use of the theory of difference equations in the form of recurrent linear relationships for state variables on the boundaries of the converter periods. Methodology. The article is devoted to the solution of the problem of reducing the cost of computer time to achieve the steady state of the thyristor converter. For this, it is proposed to use difference equations, for which the values of the state variables at the limits of the periods of the converter's operation are taken as variables. These values are accumulated during the initial periods of the transient process of the converter, after which the coefficients of the difference equations are calculated, and the following limit values of the state variables are found using the defined difference equations. A program in the algorithmic language of the MATLAB system is presented, which implements the proposed method and algorithm compatible with the visual model of the converter. Results. The theoretical foundations of the proposed method and the area of its applicability are substantiated. Recommendations are presented for determining the number of periods of the flow process that must be calculated for further implementation of the method. An algorithm for forming matrix relations for determining the coefficients of difference equations with respect to the values of state variables at the boundaries of periods is shown. Matrix equations are given that allow calculating the parameters of the steady state. All stages of the algorithm are illustrated with numerical examples. Originality. The method rationally combines all the advantages of visual modeling based on the numerical integration of equations using the method of state variables for the periods of operation of the converter with the analytical solution of the recurrence relations obtained on this basis for the values of state variables at the boundaries of adjacent periods. Practical value. The proposed method makes it possible to reduce by several orders of magnitude the computer time spent on calculating the parameters of the steady-state mode of the converter and, at the same time, to significantly improve the accuracy of these calculations. The practical application of the method is very effective in research and design of thyristor converters of electrical energy parameters.
Analysis and testing of internal combustion engine driven linear alternator
(Національний технічний університет "Харківський політехнічний інститут", 2023) Arslan, Serdal; Mellah, Hacene
Introduction. Internal combustion engine technology has been considered for the alternator system in the last two decades. Especially when considering fuel diversity, reliability, portability, power density, research studies are increasing day by day. In this respect, interest has been focused on linear generator studies. Purpose. The goal of the research is to investigate the performance of a linear generator and its application to generate electrical energy from an internal combustion engine to solve the range problem of small electric powered vehicles. The generator, unlike a traditional generator, consists of a linear generator with a crank mechanism driven by an internal combustion engine. Originality. The configuration of the linear generator with internal combustion engine crank has not previously been reported. Methods. The numerical solution of the generator was carried out by the finite element method in the Ansys Maxwell software in a cylindrical coordinate system. The effect of stroke length and frequency on voltage and output power was investigated by monitoring an external electrical load. A prototype linear generator has been designed and produced considering the sizing dimensions. The configuration can be used in power-hungry applications and increase the range of small electric vehicles. Results. The results from simulation and practice are largely in agreement. Practical value. A practical mechanical system was built comprising a linear generator connected to a 2.2 kW internal combustion engine via a crank connecting rod for analysis.
Analysis of text augmentation algorithms in artificial language machine translation systems
(Національний технічний університет "Харківський політехнічний інститут", 2023) Havrashenko, Anton; Barkovska, Olesia
The work is devoted to the development of an organizational model of the machine translation system of artificial languages. The main goal is the analysis of text augmentation algorithms, which are significant elements of the developed machine translation system at the stage of improvement of new dictionaries created on the basis of already existing dictionaries. In the course of the work was developed a model of the machine translation system, created dictionaries based on texts and based on already existing dictionaries using augmentation methods such as back translation and crossover; improved dictionary based on algorithms of n-grams, Knuth-Morris-Pratt and word search in the text (such as binary search, tree search, sqrt decomposition). In addition, the work implements the possibility of using the prepared dictionary for translation. Obtained results can improve existing systems of machine translation of the text of artificial languages. Practical significance of this work is the analysis and improvement of text augmentation algorithms by changing the prefix tree type. Compared to the conventional algorithm, the improved algorithm reduced the memory usage by almost 13 times, which allows it to be used on much larger test data. This was achieved by changing the internal system of the node of the prefix tree from constant references to an expandable list.
Analysis of the thermal state of the electromagnetic mill inductor with oil cooling in stationary operation modes
(Національний технічний університет "Харківський політехнічний інститут", 2023) Milykh, V. I.; Shaida, V. Р.; Yurieva, O. Yu.
An electromagnetic mill (EMM) for the technological processing of various substances, which is based on the stator of a three-phase induction motor, is being studied. The stator winding has an increased current density, so the mill is provided with a system of forced cooling with transformer oil. Problem. Currently, there are no works on the thermal state calculation of the EMM with the given design and oil cooling. Therefore, the study of such EMMs thermal state is relevant, as it will contribute to increasing the reliability and efficiency of their work. Goal. Formation of a mathematical model of the thermal state of the electromagnetic mill inductor and the analysis of its heating in stationary modes of operation with cooling by transformer oil. Methodology. The problem of calculating the thermal state, namely the temperature distribution in the main parts of the electromagnetic mill, is solved by the equivalent thermal resistance circuit method. The design of the EMM is provided in a sufficiently complete volume, and on this basis, a corresponding equivalent thermal replacement circuit is formed, which is supplemented by an equivalent hydraulic circuit of oil passageways. An explanation is provided for the composition and solution of the equations algebraic system that describes the distribution of temperatures by the constituent elements of the EMM. Results. The thermal calculation results of the electromagnetic mill showed that the maximum heating temperature is much lower than the allowable one for the selected insulation class. According to the hydraulic scheme, the necessary oil consumption, its average speed and the corresponding pressure at the inlet of the intake pipe are determined, which are at an acceptable level. It is noted that the rather moderate temperature state of the inductor and the hydraulic parameters of the oil path are facilitated by such innovations in the design of the EMM as the loop double layer short chorded winding and axial ventilation channels in the stator core. Originality. Now EMM thermal equivalent circuits with air cooling only have been presented. Therefore, the developed thermal circuit of the oil-cooled inductor is new and makes it possible to evaluate the operating modes of the EMM. Practical value. The proposed technical solutions can be recommended for practical implementation in other EMMs. Taking into account the identified reserves of the EMM temperature state, a forecast was made regarding the transition from its oil cooling to air cooling. But the use of air cooling requires a change in the design of the EMM.
Application of a wavelet neural network approach to detect stator winding short circuits in asynchronous machines
(Національний технічний університет "Харківський політехнічний інститут", 2023) Sakhara, S.; Brahimi, M.; Nacib, L.; Layadi, T. M.
Nowadays, fault diagnosis of induction machines plays an important role in industrial fields. In this paper, Artificial Neural Network (ANN) model has been proposed for automatic fault diagnosis of an induction machine. The aim of this research study is to design a neural network model that allows generating a large database. This database can cover maximum possible of the stator faults. The fault considered in this study take into account a short circuit with large variations in the machine load. Moreover, the objective is to automate the diagnosis algorithm by using ANN classifier. Method. The database used for the ANN is based on indicators which are obtained from wavelet analysis of the machine stator current of one phase. The developed neural model allows to taking in consideration imbalances which are generated by short circuits in the machine stator. The implemented mathematical model in the expert system is based on a three-phase model. The mathematical parameters considered in this model are calculated online. The characteristic vector of the ANN model is formed by decomposition of stator current signal using wavelet discrete technique. Obtained results show that this technique allows to ensure more detection with clear evaluation of turn number in short circuit. Also, the developed expert system for the taken configurations is characterized by high precision.
Application of whale algorithm optimizer for unified power flow controller optimization with consideration of renewable energy sources uncertainty
(Національний технічний університет "Харківський політехнічний інститут", 2023) Laifa, Abdelaziz; Ayachi, Bilel
Purpose. In this paper an allocation methodology of Flexible Alternating Current Transmission Systems (FACTS) controllers, more specifically, the Unified Power Flow Controller (UPFC) is proposed. As the penetration of Renewable Energy Sources (RESs) into the conventional electric grid increases, its effect on this location must be investigated. Research studies have shown that the uncertainty of RESs in power generation influences the reactive power of a power system network and consequently its overall transmission losses. The novelty of the proposed work consists in the improvement of voltage profile and the minimization of active power loss by considering renewable energy sources intermittency in the network via optimal location of UPFC device. The allocation strategy associates the steady-state analysis of the electrical network, with the location and adjustment of controller parameters using the Whale Optimization Algorithm (WOA) technique. Methodology. In order to determine the location of UPFC, approaches are proposed based on identification of a line which is the most sensitive and effective with respect to voltage security enhancement, congestion alleviation as well as direct optimization approach. The optimum location of UPFC in the power system is discussed in this paper using line loading index, line stability index and optimization method. The objective function is solved using the WOA algorithm and its performance is evaluated by comparison with Particle Swarm Optimization (PSO) algorithm. Results. The effectiveness of the proposed allocation methodology is verified through the analysis of simulations performed on standard IEEE 30 bus test system considering different load conditions. The obtained results demonstrate that feasible and effective solutions are obtained using the proposed approach and can be used to overcome the optimum location issue. Additionally, the results show that when UPFC device is strategically positioned in the electrical network and uncertainty of RES is considered, there is a significant influence on the overall transmission loss and voltage profile enhancements of the network.
Bipolar DC output fed grounded DC-AC converter for photovoltaic application
(Національний технічний університет "Харківський політехнічний інститут", 2023) Sindhuja, R.; Padma, S.
Introduction. In recent years the usage of electricity has increased tremendously as the electrical needs and loads got increased. Hence the researchers focused on the electricity generation from renewable sources in order to promote sustainable green environment. Owing to the lesser cost and more reliable high efficiency system with reduced use of equipments became prominent for the grid connected photovoltaic single phase systems. The novelty of this proposed converters are to reduce total power loss and to analyze the performance of the converter under various modulation index and to have lesser harmonics using sinusoidal pulse width modulation technique for both T-type and F-type inverter. Interest of the work is to merge two DC-DC converters which have same output voltage in order to have transformer less utilization of power. This has given pathway to develop a new DC-DC converter network by merging the common input nodes of CUK and SEPIC converter. Purpose. This similar structure of both converters made it easy to combine the input stages of and to get bipolar output. Methods. Here we can get bipolar output without the utilization of transformer which minimizes the overall size of the proposed system. In this paper, a combined CUK-SEPIC based grid connected transformerless inverter for photovoltaic application is suggested. Results. The suggested converter is simulated using MATLAB and the results were discussed. Further the circuit is extended with a 1 kW F-type inverter to demonstrate grid connection of the converter. Practical value. This converter can be implemented for photovoltaic applications for obtaining the bipolar DC output from the DC source.
Cascade sliding mode maximum power point tracking controller for photovoltaic systems
(Національний технічний університет "Харківський політехнічний інститут", 2023) Hessad, M. A.; Bouchama, Z.; Benaggoune, S.; Behih, K.
Introduction. Constant increases in power consumption by both industrial and individual users may cause depletion of fossil fuels and environmental pollution, and hence there is a growing interest in clean and renewable energy resources. Photovoltaic power generation systems are playing an important role as a clean power electricity source in meeting future electricity demands. Problem. All photovoltaic systems have two problems; the first one being the very low electric-power generation efficiency, especially under low-irradiation states; the second resides in the interdependence of the amount of the electric power generated by solar arrays and the ever changing weather conditions. Load mismatch can occur under these weather varying conditions such that maximum power is not extracted and delivered to the load. This issue constitutes the so-called maximum power point tracking problem. Aim. Many methods have been developed to determine the maximum power point under all conditions. There are various methods, in most of them based on the well-known principle of perturb and observe. In this method, the operating point oscillates at a certain amplitude, no matter whether the maximum power point is reached or not. That is, this oscillation remains even in the steady state after reaching the maximum power point, which leads to power loss. This is an essential drawback of the previous method. In this paper, a cascade sliding mode maximum power point tracking control for a photovoltaic system is proposed to overcome above mentioned problems. Methodology. The photovoltaic system is mainly composed of a solar array, DC/DC boost converter, cascade sliding mode controller, and an output load. Two sliding mode control design strategies are joined to construct the proposed controller. The primary sliding mode algorithm is designed for maximum power point searching, i.e., to track the output reference voltage of the solar array. This voltage is used to manipulate the setpoint of the secondary sliding mode controller, which is used via the DC-DC boost converter to achieve maximum power output. Results. This novel approach provides a good transient response, a low tracking error and a very fast reaction against the solar radiation and photovoltaic cell temperature variations. The simulation results demonstrate the effectiveness of the proposed approach in the presence of environmental disturbances.
Determination of the scope of the experimental-calculation method for measuring the touch voltage
(Національний технічний університет "Харківський політехнічний інститут", 2023) Koliushko, D. G.; Rudenko, S. S.; Saliba, Abdel Nour
The work is devoted to the improvement of methods for determining the normalized parameters of the grounding system (GS) of operating power stations and substations. The aim of the work is determination of the scope of the experimental-calculated method for measuring the touch voltage, depending on short-circuit (SC) current value for the given dimensions of the GS and the type of soil. Methodology. The study analyzed the non-linear effect of the SC current value on the touch voltage, taking into account such factors as the GS size and the soil type. The calculation used statistical data on the GS size and the characteristics of the soil obtained by monitoring the GS state of 585 operating electrical substations with a voltage class of 110-750 kV using the induction method and the method of vertical soil sounding, respectively. For the calculation, a mathematical model of a non-equipotential GS located in a three-layer semiconductor space with plane-parallel boundaries was used, this model was developed using the method of integro-differential equations. Results. To determine the scope of the method, in this work it is proposed to use the linearity criterion, which is determined due to the ratio of the constant of reduced touch voltage to the current value. The example shows the method for determining the threshold minimum and maximum values of the measuring current of the soil, in the range between which the measurements by experimental-calculated methods are impossible. A table of threshold current values has been formed and recommendations have been developed on the possibility of using experimental-measuring methods for determining the touch voltage depending on the GS size and soil characteristics.
Direct power control using space vector modulation strategy control for wind energy conversion system using three-phase matrix converter
(Національний технічний університет "Харківський політехнічний інститут", 2023) Boukadoum, A.; Bouguerne, A.; Bahi, T.
Wind energy conversion system is getting a lot of attention since, they are provide several advantages, such as cost competitive, environmentally clean, and safe renewable power source as compared with the fossil fuel and nuclear power generation. A special type of induction generator, called a doubly fed induction generator is used extensively for high-power wind energy conversion system. They are used more and more in wind turbine applications due to the advantages of variable speed operation range and its four quadrants active and reactive power capabilities, high energy efficiency, and the improved power quality. Wind energy conversion systems require a good choice of power electronic converters for the improvement of the quality of the electrical energy produced at the generator terminals. There are several power electronics converters that are the most popular such as the two stage back-back converter. Because of the disadvantage of these converters to produce large harmonics distortions, we will choose using of three-phase matrix converter. Purpose. Work presents a direct power control using space vector modulation for a doubly fed induction generator based wind turbine. The main strategy control is to control the active and reactive powers and reduce the harmonic distortion of stator currents for variable wind speed. The novelty of the work is to use a doubly fed induction machine and a three pulses matrix converter to reduce the low cost, volume and the elimination of the grid side converter controller are very attractive aspects of the proposed topology compared to the conventional methods such as back-to-back converters. Simulation results are carried out on a 1.5 MW of wind energy conversion system connected to the grid. The efficiency of the proposed system has been simulated and high results performances are evaluated to show the validity of the proposed control strategy to decouple and control the active and reactive power for different values of wind speed.
Dynamic measurement of magnetic characteristics of switched reluctance motor
(Національний технічний університет "Харківський політехнічний інститут", 2023) Fan, Jiayi; Lee, Yongkeun
Introduction. Switched reluctance motor (SRM) is a type of electric motor featuring nonlinear magnetic characteristics. The flux linkage or inductance profile of SRM is usually required for the purpose of high control performance, and can be normally obtained through conventional static test by using DC or AC method when the rotor is locked. Problem. However, it is not practical to use the conventional method of measurement when the specific apparatus for locking the rotor is unavailable. Besides, due to the magnetic nonlinearity of SRM, the saturation effect makes it difficult to obtain the saturated magnetic characteristics, and the conventional static AC test fails to address this problem. Novelty. In this paper, a dynamic measurement method of the magnetization curves of SRM is proposed which allows the measurement take place while the motor is running with load. Methodology. Based on the conventional static AC test, the proposed measurement handles the saturation problem successfully by introducing a DC offset in the high frequency AC voltage. Phase inductance with different rotor positions and currents can be obtained by analyzing simple equivalent circuit. Practical value. Simulation is conducted in MATLAB/Simulink environment and the results have verified that the proposed dynamic measurement can effectively obtain the magnetic characteristics of SRM.
Efficiency enhancement strategy implementation in hybrid electric vehicles using sliding mode control
(Національний технічний університет "Харківський політехнічний інститут", 2023) Ibrar, Anas; Ahmad, Sohaira; Safdar, Ayla; Haroon, Nazo
Introduction. Hybrid electric vehicles are offering the most economically viable choices in today's automotive industry, providing best solutions for a very high fuel economy and low rate of emissions. The rapid progress and development of this industry has prompted progress of human beings from primitive level to a very high industrial society where mobility used to be a fundamental need. However, the use of large number of automobiles is causing serious damage to our environment and human life. At present most of the vehicles are relying on burning of hydrocarbons in order to achieve power of propulsion to drive wheels. Therefore, there is a need to employ clean and efficient vehicles like hybrid electric vehicles. Unfortunately, earlier control strategies of series hybrid electric vehicle fail to include load disturbances during the vehicle operation and some of the variations of the nonlinear parameters (e.g. stator's leakage inductance, resistance of winding etc.). The novelty of the proposed work is based on designing and implementing two robust sliding mode controllers (SMCs) on series hybrid electric vehicle to improve efficiency in terms of both speed and torque respectively. The basic idea is to let the engine operate only when necessary keeping in view the state of charge of battery. Purpose. In proposed scheme, both performance of engine and generator is being controlled, one sliding mode controllers is controlling engine speed and the other one is controlling generator torque, and results are then compared using 1-SMC and 2-SMC's. Method. The series hybrid electric vehicle powertrain considered in this work consists of a battery bank and an engine-generator set which is referred to as the auxiliary power unit, traction motor, and power electronic circuits to drive the generator and traction motor. The general strategy is based on the operation of the engine in its optimal efficiency region by considering the battery state of charge. Results .Mathematical models of engine and generator were taken into consideration in order to design sliding mode controllers both for engine speed and generator torque control. Vehicle was being tested on standard cycle. Results proved that, instead of using only one controller for engine speed, much better results are achieved by simultaneously using two sliding mode controllers, one controlling engine speed and other controlling generator torque.
Efficient method for transformer models implementation in distribution load flow matrix
(Національний технічний університет "Харківський політехнічний інститут", 2023) Kadri, M.; Hamouda, A.; Sayah, S.
Most distribution networks are unbalanced and therefore require a specific solution for load flow. There are many works on the subject in the literature, but they mainly focus on simple network configurations. Among the methods dedicated to this problem, one can refer to the load flow method based on the bus injection to branch current and branch current to bus voltage matrices. Problem. Although this method is regarded as simple and complete, its drawback is the difficulty in supporting the transformer model as well as its winding connection types. Nevertheless, the method requires the system per unit to derive the load flow solution. Goal. In the present paper, our concern is the implementation of distribution transformers in the modeling and calculation of load flow in unbalanced networks. Methodology. Unlike previous method, distribution transformer model is introduced in the topology matrices without simplifying assumptions. Particularly, topology matrices were modified to take into account all winding types of both primary and secondary sides of transformer that conserve the equivalent scheme of an ideal transformer in series with an impedance. In addition, the adopted transformer models overcome the singularity problem that can be encountered when switching from the primary to the secondary side of transformer and inversely. Practical value. The proposed approach was applied to various distribution networks such as IEEE 4-nodes, IEEE 13-nodes and IEEE 37-nodes. The obtained results validate the method and show its effectiveness.
Energy characteristics for nanosecond current interrupter of semiconductor-magnetic pulse generator’s terminal stage
(Національний технічний університет "Харківський політехнічний інститут", 2023) Khrysto, O. I.
A semiconductor diode based on reverse current interruption is used to increase a pulse amplitude and peak power delivered on the process load. Usually, a current interrupter is located in the last stage of semiconductor-magnetic pulse generator (SMPG) and is connected in parallel to the load. Problem. Most of publications on this topic mostly concern with analysis of physical processes in the diode structure itself within its oscillating circuit, which is separated from previous SMPG’s pulse compression stages under condition of unidirectional energy transfer from the generator to the load. In this sense, the efficiency of conversion should be determined by the joint of electromagnetic interaction between non-linear compression stages, current interrupter and process load. Goal. Develop a mathematical model of nanosecond current interrupter to determine its electrical and energy characteristics as a part of high-voltage parallel circuit with magnetic pulse compression, depending on the duration and moment of current interruption, the equivalent circuit for load resistance, and to set the most optimal modes of its operation. Methodology. In this work, it is proposed to use a comprehensive approach aimed at the study of electromagnetic processes in the SMPG’s circuits with a nanosecond current interrupter, which takes into account the topology of circuit, the design parameters of saturable reactor, the magnetization curve, the equivalent load’s resistance, as well as the time parameters of power switches. Results. Analytical expressions describing the electrical and energy characteristics of the interrupter when it operating on the active load are obtained. A numerical simulation of interrupter in the SMPG’s double-loop pumping circuit is carried out, taking into account a nonlinearity of SR’s magnetization curve. Three operation modes of interrupter is described, depending on the initial moment of reverse conduction current interruption. The analysis of interrupter operation on the load with an active-capacitive component is carried out. Practical meaning. The results of research can be applied in development of high-voltage SMPG scheme with improved energy-dynamic parameters.
Energy management based on a fuzzy controller of a photovoltaic/fuel cell/Li-ion battery/supercapacitor for unpredictable, fluctuating, high-dynamic three-phase AC load
(Національний технічний університет "Харківський політехнічний інститут", 2023) Ayat, Y.; Badoud, A. E.; Mekhilef, S.; Gassab, S.
Nowadays, environmental pollution becomes an urgent issue that undoubtedly influences the health of humans and other creatures living in the world. The growth of hydrogen energy increased 97.3 % and was forecast to remain the world’s largest source of green energy. It can be seen that hydrogen is one of the essential elements in the energy structure as well as has great potential to be widely used in the 21st century. Purpose. This paper aims to propose an energy management strategy based a fuzzy logic control, which includes a hybrid renewable energy sources system dedicated to the power supply of a three-phase AC variable load (unpredictable high dynamic). Photovoltaic (PV), fuel cell (FC), Li-ion battery, and supercapacitor (SC) are the four sources that make up the renewable hybrid power system; all these sources are coupled in the DC-link bus. Unlike usual the SC was connected to the DC-link bus directly in this research work in order to ensure the dominant advantage which is a speedy response during load fast change and loads transient. Novelty. The power sources (PV/FC/Battery/SC) are coordinated based on their dynamics in order to keep the DC voltage around its reference. Among the main goals achieved by the fuzzy control strategy in this work are to reduce hydrogen consumption and increase battery lifetime. Methods. This is done by controlling the FC current and by state of charge (SOC) of the battery and SC. To verify the fuzzy control strategy, the simulation was carried out with the same system and compared with the management flowchart strategy. The results obtained confirmed that the hydrogen consumption decreased to 26.5 g and the SOC for the battery was around 62.2-65 and this proves the desired goal.
Evaluation of system controlled parameters informational importance, taking into account the source data inaccuracy
(Національний технічний університет "Харківський політехнічний інститут", 2023) Raskin, Lev; Sukhomlyn, Larysa; Sokolov, Dmytro; Vlasenko, Vitalii
The purpose of the study is to improve the standard methodology for controlled parameters information value assessing. The proposed method is based on the controlled parameters value probabilities analysis falling into the subintervals of the interval of possible values for different states of the system. When the value of the controlled parameter falls into the left or right boundary subintervals of the compatibility interval for any state of the object, the conclusion about its state is made taking into account possible errors of the first or second kind in this case. When the controlled parameter value enters the central subinterval, useful information appears if the corresponding probabilities for the states H₁ and H₂ are differ significantly. Thus, it is shown that taking into account the probabilities of fuzzy values of the controlled parameter falling into the compatibility interval for various states of the object significantly increases its informational value.
Exploration and mitigation of power quality problems in radial distribution system by placing distributed generation through voltage stability index
(Національний технічний університет "Харківський політехнічний інститут", 2023) Manohara, M.; Veera Reddy, V. C.; Vijaya Kumar, M.
Introduction. Distributed generation has played an important role in many aspects of sustainability, such as improving voltage profiles and reducing power losses, in the distribution network. Problem. Frequent variation of loads causes many complications while placing and sizing of distributed generation in the radial distribution network, via quality of supply, and stability of the system. Goal of the paper is to investigate and mitigate the power quality issues towards stabilizing the system during distributed generations placed in the system under various loading conditions. Methodology. The line voltage stability index analyses and enhances the performance of the radial distribution network by effective sizing and location of distributed generation towards the objective function. Practical value. A standard test system IEEE-69 bus radial distribution network is used to understand through MATLAB environment.
Extended mixed integer quadratic programming for simultaneous distributed generation location and network reconfiguration
(Національний технічний університет "Харківський політехнічний інститут", 2023) Tami, Youcef; Sebaa, Karim; Lahdeb, Mohamed; Usta, Omer; Nouri, Hassan
Introduction. To minimise power loss, maintain the voltage within the acceptable range, and improve power quality in power distribution networks, reconfiguration and optimal distributed generation placement are presented. Power flow analysis and advanced optimization techniques that can handle significant combinatorial problems must be used in distribution network reconfiguration investigations. The optimization approach to be used depends on the size of the distribution network. Our methodology simultaneously addresses two nonlinear discrete optimization problems to construct an intelligent algorithm to identify the best solution. The proposed work is novel in that it the Extended Mixed-Integer Quadratic Programming (EMIQP) technique, a deterministic approach for determining the topology that will effectively minimize power losses in the distribution system by strategically sizing and positioning Distributed Generation (DG) while taking network reconfiguration into account. Using an efficient Quadratic Mixed Integer Programming (QMIP) solver (IBM ®), the resulting optimization problem has a quadratic form. To ascertain the range and impact of various variables, our methodology outperforms cuttingedge algorithms described in the literature in terms of the obtained power loss reduction, according to extensive numerical validation carried out on typical IEEE 33- and 69-bus systems at three different load factors. Practical value. Examining the effectiveness of concurrent reconfiguration and DG allocation versus sole reconfiguration is done using test cases. According to the findings, network reconfiguration along with the installation of a distributed generator in the proper location, at the proper size, with the proper loss level, and with a higher profile, is effective.
Fault diagnosis in a five-level multilevel inverter using an artificial neural network approach
(Національний технічний університет "Харківський політехнічний інститут", 2023) Parimalasundar, Ezhilvannan; Senthil Kumar, Ramanathan; Chandrika, Vanitha Selvaraj; Suresh, Krishnan
Introduction. Cascaded H-bridge multilevel inverters (CHB-MLI) are becoming increasingly used in applications such as distribution systems, electrical traction systems, high voltage direct conversion systems, and many others. Despite the fact that multilevel inverters contain a large number of control switches, detecting a malfunction takes a significant amount of time. In the fault switch configurations diode included for freewheeling operation during open-fault condition. During short circuit fault conditions are carried out by the fuse, which can reveal the freewheeling current direction. The fault category can be identified independently and also failure of power switches harmed by the functioning and reliability of CHB-MLI. This paper investigates the effects and performance of open and short switching faults of multilevel inverters. Output voltage characteristics of 5 level MLI are frequently determined from distinctive switch faults with modulation index value of 0.85 is used during simulation analysis. In the simulation experiment for the modulation index value of 0.85, one second open and short circuit faults are created for the place of faulty switch. Fault is identified automatically by means of artificial neural network (ANN) technique using sinusoidal pulse width modulation based on distorted total harmonic distortion (THD) and managed by its own. The novelty of the proposed work consists of a fast Fourier transform (FFT) and ANN to identify faulty switch. Purpose. The proposed architecture is to identify faulty switch during open and short failures, which has to be reduced THD and make the system in reliable operation. Methods. The proposed topology is to be design and evaluate using MATLAB/Simulink platform. Results. Using the FFT and ANN approaches, the normal and faulty conditions of the MLI are explored, and the faulty switch is detected based on voltage changing patterns in the output. Practical value. The proposed topology has been very supportive for implementing non-conventional energy sources based multilevel inverter, which is connected to large demand in grid.
Fault diagnosis of power converters in a grid connected photovoltaic system using artificial neural networks
(Національний технічний університет "Харківський політехнічний інститут", 2023) Mimouni, Amina; Laribi, Saadi Souad; Sebaa, Morsli; Allaoui, Tayeb; Bengharbi, Abdelkader Azzeddine
Introduction. The widespread use of photovoltaic systems in various applications has spotlighted the pressing requirement for reliability, efficiency and continuity of service. The main impediment to a more effective implementation has been the reliability of the power converters. Indeed, the presence of faults in power converters that can cause malfunctions in the photovoltaic system, which can reduce its performance. Novelty. This paper presents a technique for diagnosing open circuit failures in the switches (IGBTs) of power converters (DC-DC converters and three-phase inverters) in a grid-connected photovoltaic system. Purpose. To ensure supply continuity, a fault-diagnosis process is required throughout all phases of energy production, transfer, and conversion. Methods. The diagnostic approach is based on artificial neural networks and the extraction of features corresponding to the open circuit fault of the IGBT switch. This approach is based on the Clarke transformation of the three-phase currents of the inverter output as well as the calculation of the average value of these currents to determine the exact angle of the open circuit fault. Results. This method is able to effectively identify and localize single or multiple open circuit faults of the DC-DC converter IGBT switch or the three-phase inverter IGBT switches.

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