Analysis Of Transient Processes Research Articles

IMPLEMENTATION OF SIMOYU METHOD FOR MODELING OF TRANSIENTS OF CONTROL OBJECT

In this paper transients in the control system are investigated on the basis of experimental data. The construction of the transfer function of the control object using Simoyu method is realized by means of Python language. The model of the control system of the object, selection of the regulator and its settings are implemented using SimInTech modeling environment. Within the framework of the conducted research, methodological approaches to the formation of transfer functions of control objects represented in the form of polynomial expressions of various degrees of complexity, starting with polynomials of the first degree in the numerator and the second degree in the denominator, and ending with polynomials of the second degree in the denominator against the third degree in the numerator, have been developed and tested. A procedure for reading data in CSV format was used to build the Python program interface, which helped to simplify the integration of experimental results with analytical tools, providing a powerful platform for subsequent analysis, visualization, and interpretation of the resulting transfer functions. The procedures of debugging and optimization of the technique of visualization of results and estimation of calculation errors have been carried out, which allowed to provide a visual representation of data and high accuracy of the obtained transfer functions. In contrast to the known analytical studies in the field of differential equations describing transient processes, the use of numerical methods implemented by means of Python libraries and programming environments, in particular SimInTech, allows to simplify the analysis of transient processes of control objects.

Research of the Primary Electric Energy Storage System of a Traction Photovoltaic Module

Purpose. The main idea of the work is that the electric energy generated by photovoltaic installations is supplied in small parts to capacitive energy storage devices of low power, and then these «portions» of energy are supplied to one common, so-called traction storage device. The research is aimed at obtaining time diagrams of current and voltage changes in the proposed system. Methodology. A review of the world literature on the topic of work was conducted. The basis of this research is the analysis of transient processes in the electrical circuits of the system during the transfer of energy from the photovoltaic module to the traction capacitor under the influence of various control signals: series, parallel, combined. The main research method is computer simulation. The Scilab software environment was used to simulate the operation of the electric energy storage system. Findings. The relevance of the research and development of a primary electric energy storage system using a traction photovoltaic module has been proved. The key mathematical dependencies between the parameters of the constituent elements of electrical circuits are established. The structure of a site with electric energy storage with traction photovoltaic modules and a converter-pulse signal unit is proposed. The graphical characteristics of transient processes that occurred during the transfer of energy from low-power capacitive elements to a high-power capacitive element (traction capacitor) were obtained. Originality. For the first time, graphical dependences of energy transfer between system elements were obtained, which allows for a reasonable choice of the parameters of these elements. Also, for the first time, time dependencies describing the law of control of the process of energy transfer between system links were obtained, which will allow determining the rational modes of its operation. Practical value. The results of the research open up new opportunities in the research field in the development of large-scale experimental models of the maglev path structure in the case of the introduction of a system of distributed primary energy storage in a traction photovoltaic module.

Identification of Damages to Electrical Networks through the Spectral Analysis of Transient Processes

Identification of Damages to Electrical Networks through the Spectral Analysis of Transient Processes

The Influence of Pump-Turbine Specific Speed on Hydraulic Transient Processes

The main porpose of this paper is to perform and present at transient process analysis on the influence of different specific speeds (nq) of the three-model pump-turbines that may implemented at the hydropower pump storage plant (HPSP) Bajina Basta, Serbia. The intention is to analyze the operation regimes along the S-shaped characteristic curve, which creates difficulties in calculations during the load-rejection process. These problems are manifested by an unusual increase in water pressure, followed by an increase in machine vibrations, thus threatening the stability of machine operation. The subject of this research is the four-quadrant (4Q) characteristic curves, presented in the form of Suter curves (the head and momentum parameters (Wh and Wm), in dependence of angle (θ)) for different wicket gate openings, of the three pump-turbine models with different specific speeds (nq = 27, nq = 38 and nq = 50). These 4Q characteristics are used as input data for numerical code developed to calculate the simultaneous load rejection of both pump-turbines. The numerical code is based on the method of characteristics and applied to the test case at HPSP. This is especially relevant when dealing with characteristic S-shaped curves that may lead to serious instability in operation during the transient process. The calculation results show changes in the pressure, speed of rotation and discharge of the machine operation regimes, but the important findings are reflected in further application of the results to determine the parametric flow and speed (Q11 and n11) trajectories of the operating points, where the unstable behavior of a pump-turbine operating in turbine mode is presented and periodically the trajectories also pass through the reverse pump zone.

Modeling of informative features based on the amplitude-phase frequency response during bioimpedance studies at a biological facility

The purpose of research is to develop and test a technique for forming informative features using descriptors for neural networks designed to assess medical risks based on the analysis of transient processes in biomaterial in a living organism (in vivo).Methods. Studies suggest the use of test electrical effects on areas of the body with unusual conductivity to obtain the amplitude-phase-frequency characteristic of the impe-dance of the biomaterial on which the specified effect was performed. The coordinates of the Cole graph of this biomaterial were used as key para-meters. To form the Cole graph, the Carson transform was used, based on transient data obtained using a four-terminal, where the main element is the impedance of the studied biomaterial. The input signals for the four-terminal were a sequence of sinusoidal pulses.Results. Based on the E20-10 data collection system manufactured by L-Card CJSC, a software and hardware complex has been developed for digitizing transient processes in four-terminal circuits, the element of which is the impedance of biomaterial in anatomical areas with abnormal electrical conductivity. Software in the Delphi programming language was developed to generate test signals and record biomaterial responses to these exposures. A theoretical model was also proposed explaining the conversion of the samples of the transition characteristic of the four-terminal with the impedance of the biomaterial to the Cole graph of this biomaterial.Conclusion. The study confirms that the use of a linear biomaterial impedance model contributes to the formation of descriptors based on the amplitude-phase-frequency characteristic, taking into account its dissipative properties. Building a Cole graph taking into account these dissipative characteristics allows us to develop classifiers of medical risks of socially significant diseases.

Inversion Calculation and Analysis of Transient Process for Pumped Storage Power Station

Abstract In order to more accurately evaluate the transition process characteristics of pump turbine in pumped storage power station, this paper summarized a systematic inversion calculation and analysis method. Using this inversion calculation method, this paper calculated and analyzed the pressure changes for different load conditions of the same unit, similar conditions of other units in the same hydraulic unit and similar conditions of similar units in other hydraulic units based on the actual measured data of load rejecting test in a pumped storage power station. The inversion calculation results are in good agreement with the experimental measured data, which proves that it is feasible to predict the transient pressure by using this method for inversion calculation.

Methodology for Transient Stability Enhancement of Power Systems Based on Machine Learning Algorithms and Fast Valving in a Steam Turbine

This study presents the results of the development and testing of a methodology for selecting parameters of the characteristics of fast valving in a steam turbine for emergency power system management to maintain dynamic stability based on machine learning algorithms. Modern power systems have reduced inertia and increased stochasticity due to the active integration of renewable energy sources. As a result, there is an increased likelihood of incorrect operation in traditional emergency automation devices, developed on the principles of deterministic analysis of transient processes. To date, it is possible to increase the adaptability and accuracy of emergency power system management through the application of machine learning algorithms. In this work, fast valving in a steam turbine was chosen as the considered device of emergency automation. To form the data sample, the IEEE39 mathematical model was used, for which benchmark laws of change in the position of the cutoff valve during the fast valving of a steam turbine were selected. The considered machine learning algorithms for classifying the law of change in the position of the steam turbine’s cutoff valve, k-nearest neighbors, support vector machine, decision tree, random forest, and extreme gradient boosting were used. The results show that the highest accuracy corresponds to extreme gradient boosting. For the selected eXtreme Gradient Boosting algorithm, the classification accuracy on the training set was 98.17%, and on the test set it was 97.14%. The work also proposes a methodology for forming synthetic data for the use of machine learning algorithms for emergency management of power systems and suggests directions for further research.

Measurement of Oscillatory and Dissipative Characteristics of Solid-state Wave Gyroscope Resonators: Algorithms Based on the Analysis of Transient Processes of Free Oscillations

Measurement of Oscillatory and Dissipative Characteristics of Solid-state Wave Gyroscope Resonators: Algorithms Based on the Analysis of Transient Processes of Free Oscillations

Transient Process Analysis of Oscillating Motion in Oscillating Heat Pipes

Abstract During the startup phase, oscillating heat pipes (OHPs) exhibit a transient process in which the working fluid moves erratically until a steady-state oscillatory flow is attained. Understanding the transient process is important to predict how long it takes an oscillating heat pipe to reach normal operation and realize its heat transfer potential after it is started. In this paper, we perform a theoretical study of the transient process of oscillating heat pipes. Based on a one-dimensional mathematical model, we obtain an analytic solution that allows us to predict transient process characteristics of oscillating motions in an oscillating heat pipe, as well as the impact that different design and operating parameters have on this transient process.

Analysis of various operating modes of the microhpp asynchronous generator using the matlab simulink program

This article analyzes changes in efficiency and power factor, as well as various operating modes in the capacitor element excitation method, which is increasingly used in asynchronous generators. In this case, the sinusoidal voltage and frequency produced by the induction generator are within the rated values and different operations are compared. The studies were carried out along with the parameters obtained using the simulation model as well as real experimental verification. The simulation model was built in the Matlab Simulink package, which consisted of a rectifier, filter circuit, IGBT transistors and included a control system. In the real experiment, an asynchronous generator with a low-power squirrel-cage rotor was chosen, and sensors for measuring current and voltage were installed on the experimental stand. As a result of the analysis of transient processes occurring in different operating modes of the generator, it was found that the values of voltage, current and frequency changed from the nominal value. The results were achieved by adjusting the speed through a variable speed drive to obtain the rated speed taking into account the speed supplied to the rotor from the hydraulic turbine. At the end of the study, it was concluded that the induction generator has a number of advantages over other types of generators, including simplicity of design, low cost, and the fact that it does not consume a direct current source.

COMPARATIVE ANALYSIS OF THE SUSTAINABILITY OF FINANCIAL PROCESSES IN JSC «UKRSIBBANK» AND JSC «PRIVATBANK» USING METHODS OF MODELING ECONOMIC DYNAMICS

Objective. The objective of the present article is to conduct a comparative analysis of the stability of financial processes in JSC «Ukrsibbank» and JSC «PrivatBank» using methods of modeling economic dynamics. Methods. The following methods were used to analyze the areas of application of economic dynamics modeling methods to compare the stability of financial processes in JSC «Ukrsibbank» and JSC «PrivatBank»: the basics of the mathematical apparatus for the analysis of transient processes, correlation and autocorrelation analysis, the methodology for determining the coefficients of impulse-transitional and transient functions, methods of constructing differential models, Laplace transformation and obtaining transition functions, the basics of mathematics of imaginary quantities, methods of obtaining amplitude-phase and frequency characteristics of the object under study, methods of stability analysis of controlled dynamic processes. Results. According to the results of a comparative analysis of the stability of financial processes in JSC «Ukrsibbank» and JSC «PrivatBank», it was established that the impulse-transitional and transitional functions for JSC «PrivatBank» have a more pronounced oscillatory character, which indicates a greater level of seasonality and cyclicality of financial processes in this particular bank, in addition, it reaches higher absolute values, which indicates a greater effect of the multiplier of investments for obtaining income of this bank. It is substantiated that since the line of the amplitude-phase-frequency characteristic for both banks does not cover the point (-1;0), this indicates the stability of the studied profit-making processes and their ability to self-leveling in the event of random disturbances and force majeure circumstances. On the basis of the schedule of amplitude-phase-frequency characteristic for PrivatBank JSC, it was determined that for this bank there is a certain limit of minimum values, below which the change of the investigated influential variables (the size of the loan portfolio, the total volume of contributions and deposits of individuals) does not affect the change in net profit. For JSC «Ukrsibbank» there is no such limit at any minimum values of the selected influential variables. The expediency of applying the mathematical apparatus of analysis of transient processes (in particular, construction of a differential model, transfer, impulse transient and transient function) for researching the process of obtaining a bank's net profit depending on the dynamic changes of its other financial indicators is substantiated. By constructing the amplitude-phase-frequency characteristic of the simulated transient process of changes in bank profit, the stability of the studied process was assessed and it was determined to what extent the existing dependence between the dynamic states of the net profit indicator is resistant to external disturbances and force majeure circumstances.

Including Shield Wires in the Analysis of Transient Processes Occurring in HVAC Transmission Lines

The article presents an analysis of electromagnetic transient processes in long ultra-high voltage transmission lines, taking into account shield wires. It was shown that EMTP and Matlab/Simulink software are currently widely used in the study of transient processes in power lines. The EMTP software package uses the finite element method when integrating the equation that mathematically models the distributed parameter transmission line. The Matlab/Simulink software uses the d’Alembert method. In both cases, it is not known how the boundary conditions for the partial differential equation that mathematically models the transmission line are determined. The power line is analyzed as a distributed parameter system, described by a second-order partial differential equation. The advantage of the proposed method of calculating the boundary conditions for the abovementioned equation is the use of boundary conditions of the second and third types of Neumann and Poincaré, which allowed us to take into account the mutual influence of shield wires and phase conductors of the line in one power system. On this basis, the methodology for obtaining time domain graphs, spatial distributions, and traveling wave distributions of voltages and currents for phase conductors and line shielding wires is presented. The results of a computer simulation of transient processes when switching on the power line, taking into account controlled phase commutation and under single-phase earth fault conditions, are presented. All calculation results of transient processes presented in the article were obtained exclusively using numerical methods.

TRANSIENT PROCESSES IN ELECTRICAL COMPLEX OF PRODUCTION WELL WITH DOWNHOLE COMPENSATOR OF REACTIVE POWER

Link for citation: Glazyrin A.S., Isaev Yu.N., Kopyrin V.A., Timoshkin V.V., Kladiev S.N., Khamitov R.N., Kovalev V.Z., Losev A.F., Leonov A.P., Popov E.I. Transient processes in electrical complex of production well with downhole compensator of reactive power. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 5, рр.168-180. In Rus. The relevance. At the present time at routine complication of technological processes to increase efficiency of production processes due to introduction of new equipment conflicts between functional capabilities of various technical means and their ability to function with specified quality, in specified electromagnetic environment and do not create inadmissible electromagnetic interference to other technical means. The electrical engineering complex for oil production includes a combination of ground and submersible electrical equipment assembled for receiving, transforming electrical energy, controlling its flow, converting electrical energy into mechanical energy and transmitting it to a submersible pump, including various electrical and electronic devices: a control station with a frequency converter, a step-up transformer, a cable line, a submersible electric motor, a downhole reactive power compensator and other devices. Any change in the layout of electrical systems for extracting oil or technical characteristics of the equipment used requires careful analysis of transient processes between the operating modes of electrical equipment in order to prevent the risks of false triggering of electrical equipment protection devices. The purpose: analysis of transient processes in the electrical system of the production well with the downhole reactive power compensator when the power supply is disconnected in order to prevent the risks of false operation of the compensator protection devices. The object: section of a power supply system for a cluster of oil producing wells equipped with electric centrifugal pump installations with downhole reactive power compensators. Methods: positions of theoretical bases of electrical engineering, theory of electric drive, theory of differential equations, numerical methods. Results. The authors developed the mathematical model of the electrical system of the submersible unit for oil production with a downhole reactive power compensator, which enables to investigate transient processes in start-up and shutdown mode of the submersible induction motor. Characteristics of transient processes are obtained in elements of electrical complex of submersible plant for oil production when power supply is switched on and disconnected. It is established that the maximum current surge in the downhole reactive power compensator is 2,56 times with the parameters of the electrical system of the production well accepted in the study. The inventive measures for reducing the number of false actuations of the protection devices are also disclosed.

Analytical determination of transient current flowing through a human in contact with conductive objects under high voltage power lines

The paper inhere presents an approach for calculation of transient currents flowing through a human in contact with conductive objects under high voltage (HV) power lines by means of analytical expressions derived for that purpose. Three different case studies have been investigated and their respective equivalent circuit’s parameters have been specified and implemented: contact of an insulated from earth person with the steel-tower pole of an outdoor high voltage power line; contact of a non-insulated from earth person with a vehicle under a high voltage power line; contact of an insulated from earth person with a vehicle under a high voltage power line. The derived mathematical models and expressions have been obtained using the Mirror images method and Maxwell’s potential coefficients and the transient current trough the human body has been calculated using the Classical method for analysis of transient processes in linear electrical circuits. Conclusions have been made in regard with the degree of danger of electric shock for the three discussed case studies depending on the rated voltage and the geometrical properties of the most often met high voltage power lines in EU.

Determination of a damaged connection in single-phase earth fault

Subject of research: single-phase earth faults in electrical networks of medium voltage class.
 Purpose of resarch: the development of a simulation model for the analysis of transient processes that occur during a "metallic" single-phase earth fault in a 35 kV electrical network.
 Object of research: distribution electrical networks 6-35 kV operating in isolated neutral mode.
 Main results of research: a simulation model was developed in the Matlab Simulink environment, which makes it possible to analyze the oscillograms of currents and voltages during a single-phase earth fault in networks with an isolated neutral. A method for determining the outgoing line with an earth fault is presented, based on the superimposition of non-power frequency currents. The source frequency is determined based on the condition for the occurrence of a resonant mode. Oscillograms are presented, from which it follows that the current in the damaged phase increases by more than 2 times, which makes it possible to selectively determine the damaged connection.

АНАЛІЗ СИСТЕМИ ПАРАЛЕЛЬНОГО НЕЙРОУПРАВЛІННЯ ДИНАМІЧНИМИ ОБ'ЄКТАМИ

The article analyzes the effectiveness of the neural network control system, which together with the PIDcontroller implements the principle of parallel control of a dynamic object. As a rule, most industrialfacilities are characterized by non-linear dependencies, the presence of uncontrolled noise anddisturbances, frequent changes in equipment operating modes, and the presence of significant non-linearities. The model of the blowing subsystem of a water-tube steam boiler was used as an object ofresearch. The training of the neural network controller (NMC) and neuroemulator (emulator) was carriedout on the ACS model with a PID controller using the method of expert adjustment of tuning coefficients:proportionality, constant integration and differentiation based on the analysis of the quality indicators ofthe transition process. The change in the values of the object model parameters along the control anddisturbance channels corresponded to the dynamic modes of operation of the steam boiler in the range ofsteam load (25-110%) from the nominal one. The analysis of transient processes obtained on the basis ofcomputer modeling allows us to assert that the trained neural network control system compensates fordisturbances over the entire range of changes in the values of the object parameters along the control anddisturbance channels (simulation of changes in the steam load), as well as when the parameter values ofthe models go beyond the range study sample. Thus, the neural network controller can successfully perform the functions of an adaptive circuit tuned tothe most unfavorable disturbances in the ACS of parallel action by a complex production facility. And theimplementation of a neural network system of parallel action together with typical regulators in thetechnological processes of heat energy can reduce emergency situations associated with frequent changesin the steam load of power units caused by military actions in our country.

Measurement and Analysis of Transient Process of Electrowetting Liquid Lens

Measurement and Analysis of Transient Process of Electrowetting Liquid Lens

Non-standard analysis in electrical engineering. Transient analysis in second-order electrical circuits with violation of switching laws

For the first time, the authors proposed the use of the mathematical apparatus of non-standard analysis to solve certain non-trivial problems of theoretical electrical engineering. It was established that the axiomatics of non-standard analysis allows to simplify the analysis of transient processes in high-order electric circuits when the switching laws are violated. It is shown that the application of non-standard analysis methods in theoretical electrical engineering provides an opportunity to use the traditional classical method of transient processes analysis of circuits with violation of switching laws. Only by using methods of non-standard analysis, it is possible to strictly prove the fulfillment of the law of energy conservation in such schemes. Also, examples of solving such tasks are given. It is recommended to expand the scope of application of non-standard methods of analysis in problems of various branches of science and technology, which use differential calculus and boundary transitions, and the solution of which is limited or impossible by standard approaches.

Memory surfaces separating the processes of monotonous and cyclic loads

The processes of elastoplastic deformation of structural materials can consist of a sequence of monotonous and cyclic loading regimes, in which peculiar effects and features arise. Mathematical modeling of such processes, as well as resource assessment and forecasting, is a very difficult task. In addition, the analysis of transient processes from cyclic to monotonous and from monotonous to cyclic shows the need to separate these processes. Based on the analysis of the results of experimental studies of samples of stainless steel 12Х18Н10T under a rigid (controlled deformation) deformation process, which is a sequence of monotonic and cyclic loading modes, under conditions of uniaxial tension-compression at normal temperature, the features and differences in the processes of monotonic and cyclic loading are revealed. To describe these features and separate the processes of monotonic and cyclic loading modes in the theories of plastic flow with combined hardening, various variants of memory surfaces are introduced. An analysis of the results of experimental studies of stainless steel showed that in the space of the plastic strain tensor, the size of the memory surface is determined by the range of plastic strains, and the position of the center is determined by the values of average plastic strains under cyclic loading. Various variants of the memory surface are considered, their capabilities and disadvantages are identified, and the most adequate variant of the memory surface is determined. To confirm the operability of this version of the memory surface, together with the equations of the Bondar plasticity model, the calculated and experimental results were compared and a reliable agreement was obtained between these results both in terms of the kinetics of the stress-strain state and in terms of the number of cycles to failure.

Influence of the Electrode-Electrolyte Interface on the Product Distribution of the HMF Electroreduction

The electrochemical reduction of 5-hydroxymethylfurfural (HMF), a biomass-based platform chemical, is a promising route towards the defossilization of the transportation sector. It yields fuels, such as 2,5-dimethylfuran (DMF), and fuel precursors, such as 2,5-dihydroxymethylfuran (DHMF) and 5,5’-bis(hydroxylmethyl)hydrofuroin (BHH), while requiring only renewable resources. In order to control the selectivity of this reaction and to optimize the yield of the desired target compound, it is important to understand the reaction mechanisms towards the individual products and the influence of various system parameters. We utilize two complementary methods, namely electrochemical real-time mass spectrometry (EC-RTMS) and quantitative batch electrolysis in a flow reactor, to obtain further insights into the electrochemical HMF reduction mechanisms and the interplay between the electrode and electrolyte. While EC-RTMS is a fast screening technique, which allows for the analysis of transient processes, the batch electrolysis in the flow reactor enables product quantification by high-performance liquid chromatography (HPLC) and gas chromatography (GC) and the calculation of reaction selectivities and faradaic efficiencies. With these techniques, we were able to investigate the influence of various system parameters, such as the electrode material, the applied potential and the composition of the electrolyte, on the product distribution and propose reaction mechanisms towards the individual products.[1] References [1] R. Kloth, D. V. Vasilyev, K. J. J. Mayrhofer, I. Katsounaros, Electroreductive 5-Hydroxymethylfurfural Dimerization on Carbon Electrodes ChemSusChem 2021, 14, 5245. Figure 1