Modern Power Engineering Research Articles

Multi Objective Optimization in Charge Management of Micro Grid Based Multistory Carpark

Distributed power supply with the use of renewable energy sources and intelligent energy flow management has undoubtedly become one of the pressing trends in modern power engineering, which also inspired researchers from other fields to contribute to the topic. There are several kinds of micro grid platforms, each facing its own challenges and thus making the problem purely multi objective. In this paper, an evolutionary driven algorithm is applied and evaluated on a real platform represented by a private multistory carpark equipped with photovoltaic solar panels and several battery packs. The algorithm works as a core of an adaptive charge management system based on predicted conditions represented by estimated electric load and production in the future hours. The outcome of the paper is a comparison of the optimized and unoptimized charge management on three different battery setups proving that optimization may often outperform a battery setup with larger capacity in several criteria.

The algorithm diagram of combustion optimizing of a hydrocarbon fuels variable composition in thermal power plants

In modern power engineering, there is a problem of rational and efficient use of hydrocarbon fuels variable composition. The composition of the fuel can vary in time and from different sources. These changes lead to combustion optimum regime shift in thermal power plants. Previously, an algorithm of combustion optimizing of a hydrocarbon fuel variable composition in thermal power plants was developed. According to the algorithm, the fuel and air flows are regulated depending on the outlet temperature of the heat carrier. In this paper, a diagram of the implementation of this algorithm is presented.

The state of modern heat power engineering and increasing the economic efficiency of heat supply

The article analyzes the current state of the Russian heat power engineering and identifies the main problems in its economic development. From the position of an integrated approach, the problems of the Russian heat supply system are divided into three categories: technological, economic and social. The using electricity for the needs of heat supply is determined as an effective way of solution these problems. In this context the electric heat supply is offered as an alternative to the modern heat supply system. The article identifies the main factors of electric heating, showing its economic advantages over other types of heat supply systems. On this basis the authors justify the prospects of electric heating system from the point of view of economic development of the Fuel Energy Complex and the national economy as a whole.

Heat and mass transfer processes at high-temperature media during combustion of low-grade pulverized coal

Abstract. The article is devoted to the complex research processes of heat and mass transfer occurring in the real conditions of solid fuel (coal) combustion. Development of technological processes with economic and ecological advantages are the main purpose for many researches in thermal physics and technical physics. The complex processes of heat and mass transfer in the presence of combustion are non-stationary, strongly non-isothermal with a constant change in the physical and chemical state of the environment. It greatly complicates their experimental study. In this case, studying of heat and mass transfer in high-reacting media with simulation of physical and chemical processes occur during combustion of pulverized coal is important for the solution of modern power engineering industry and ecology problems. In this regard, a comprehensive study of heat and mass transfer processes at high-temperature media observed. Investigations based on the achievements of modern physics by using numerical methods for 3D modeling. Numerical experiments are conducted to describe and study aerodynamic characteristics, heat and mass transfer processes during the burning of pulverized Kazakhstan low-grade coal. The results obtained are of great practical importance, since they allow us to develop recommendations for the improvement and design of new combustion chambers and burners, and also can be useful in optimizing the whole process of burning fossil fuels. G M T Английский Испанский Итальянский Казахский Китайский Трад Китайский Упр Корейский Русский Турецкий Французский Английский Испанский Итальянский Казахский Китайский Трад Китайский Упр Корейский Русский Турецкий Французский Звуковая функция ограничена 200 символами Настройки : История : Обратная связь : Donate Закрыть

The Study of Philosophy in Innovative Power Engineering Post-graduate Course

Training of highly qualified personnel for the innovative high-tech fields of power engineering is one of the most important tasks of modern education. A number of special features of modern power engineering necessitate not only a highly specialized training but a wider approach in teaching postgraduate students of this field. These special features include a high degree of integration of science, industry, economic and social spheres, and the breadth of interdisciplinary connections in high-tech industries. The postgraduate philosophical training plays an important role in the educational process. The breadth of the problem field and the universality of philosophical knowledge reveal the methods and mechanisms of integration of such sub-disciplines that have significant methodological and structural differences: science, logical-mathematical, socio-economic, technological and human knowledge. Appeal to the philosophy at the stage of postgraduate training has a number of reasons. First of all, it is aimed at integrating of the specific content of different areas of knowledge into a holistic worldview. Secondly, it contributes in developing a critical attitude towards reality and science. What is more, the study of philosophy helps young researches to acquire the definition of their ideological position.

Investigation of electron cut-off in a planar diode by the magnetic field of a planar inductor

Abstract—In this paper, the electron cutoff is investigated in a flat diode by the magnetic field of an external planar inductor , using vacuum switches (VS) with flat contacts as an example. The VS are chosen for research because of the high demand for these devices in modern high-voltage power engineering. They outperform the high-voltage circuit breakers with gas and oil insulation in terms of mass-dimension and operational parameters. However, it is necessary to suppress dangerous X-ray radiation from high-voltage VS, which is generated as a result of bombardment of contact with the positive potential by electrons accelerated by the voltage applied to the contacts. Free electrons are formed in the VS during their operation due to field emission, when the distance between the contacts decreases and the electric field strength increases greatly. To prevent electronic bombardment, the cutoff effect (blocking the electron current to the anode) is used, and for its creation a radial magnetic field of the inductor is used in the form of a flat spiral located on the inoperative side of one of the contacts. The crossed fields, the axial electric field and the radial magnetic field with induction which are greater than the critical value, strongly bend the trajectories of the electrons and prevent them from bombarding contact with the positive potential. Because of the difficulties of experimental investigation of this problem, it was performed on the VS model. For this purpose, a physical topological model of VS was developed, based on a self-consistent solution of the fundamental equations that determine the electric and magnetic fields between contacts, taking into account the geometry of VS, the conductivity of the contact material and the secondary magnetic field generated by the eddy currents induced in the contact, as well as the frequency of the pulsed supply of the inductor. Calculations were made of electron trajectories emitted by a contact with a negative potential, and for those electrons that do not reach the opposite contact, the critical current of the inductor is determined, depending on the geometric parameters and operational mode. When calculating the absence or presence of one or more radial slits in contact under the inductor was taken into account. VS with a split contact is recommended. Edge effects were found at the edges of the contacts, where the orthogonality of the electric and magnetic fields is disturbed, and therefore it is proposed further to optimize the configuration of the contacts. It was suggested that the radial magnetic field of a flat inductor would be useful for cutting off electrons during the deionization of a vacuum arc plasma during the opening of contacts and for reducing the thermal effect of bombarding electrons on a positive contact. The developed model can also be used to analyse the conditions for magnetic initiation of a magnetron discharge between plane electrodes in gas discharge devices and sources of charged particles.Ref. 13, fig. 7, tabl. 2.

Bubbling in a power electronic inverter: Onset, development and detection

Power electronic DC/AC converters (inverters) play an important role in modern power engineering for a broad variety of applications including solar and wind energy systems as well as electric and hybrid cars drives. It is well known that the waveform of the output voltage (or current) of an inverter may be significantly distorted by phase restricted high frequency oscillations, frequently referred to as bubbling. However, the reasons leading to the appearance of this undesired effect are still not completely understood. Considering as an example a 2D model of a PWM H-bridge single-phase inverter, the present paper reports the appearance of two different kinds of bubbling. In the first case, the appearance of bubbling occurs suddenly and is related to the change of periodicity. We show that high-periodic, quasiperiodic and chaotic oscillations may exhibit bubbling, and also that solutions with and without bubbling may coexist. In the second case, the appearance of bubbling occurs gradually in the parameter domain where the investigated system undergoes border collisions of so-called persistence type. As a result, the appearance of the bubbling of the second kind does not change the periodicity of the motion but nevertheless disturbs the waveform. We discuss some differences in the properties of the second kind of bubbling from the first one, and present numerical techniques for its detection.

Modeling of low-grade pulverized coal combustion

The article is devoted to the complex research processes of heat and mass transfer occurring in the realconditions of solid fuel (coal) combustion. Development of technological processes with economic andecological advantages are the main purpose for many researches in thermal physics and technical physics.The complex processes of heat and mass transfer in the presence of combustion are non-stationary,strongly non-isothermal with a constant change in the physical and chemical state of the environment. Itgreatly complicates their experimental study. In this case, studying of heat and mass transfer in highreactingmedia with simulation of physical and chemical processes occur during combustion of pulverizedcoal is important for the solution of modern power engineering industry and ecology problems. In thisregard, a comprehensive study of heat and mass transfer processes at high-temperature media observed.Investigations based on the achievements of modern physics by using numerical methods for 3Dmodeling. Numerical experiments are conducted to describe and study aerodynamic characteristics, heatand mass transfer processes during the burning of pulverized Kazakhstan low-grade coal. The resultsobtained are of great practical importance, since they allow us to develop recommendations for theimprovement and design of new combustion chambers and burners, and also can be useful in optimizingthe whole process of burning fossil fuels.

Экспериментальное исследование самостабилизации частоты вращения одноцилиндрового пневматического поршневого двигателя

Generation of electricity by standalone sources is one of leading-edge avenues in the development of modern power engineering. Good-looking prospects of developments in this field are stemming from the fact that the use of nothing else but centralized power grids and generating capacities in Russia becomes impossible under the conditions of market economy in the country. Wide use of stand-alone generation of electricity on the basis of well-known heat engines is held back by impossibility to ensure highly accurate stabilization of voltage frequency (at a 50 ±0.2 Hz level) unless expensive equipment is used. The article considers an approach to solving this problem by using a generating set equipped with an expansion piston (reciprocating) engine operating in the rotation frequency self-stabilization mode (RFSS). This phenomenon is studied by taking a pneumatic piston engine as an example. Air is considered as a modeling working fluid. Steam will be used as an actual working fluid in a real cogeneration plant. One of distinctive features pertinent to operation of a piston engine with RFSS is that the working fluid flowrate remains constant irrespective of the load power, which is a positive feature during its operation in a cogeneration mode. This feature eliminates the need to use an adjustable bypass line or a separate boiler and ensures normal operation of the heat supply system when the electrical load decreases. The main objective of the study is to compare the experimental data on the generating set operation with the theoretical data (the latter were obtained on a piston engine’s simplified dynamic model in transient modes). It has been shown that this model describes the real piston engine with accuracy sufficient for engineering purposes. Owing to this circumstance, taken in combination with simplicity of the dynamic model, it became possible to derive for the first time an engineering analytical formula for the overshoot of piston engines with RFSS at a step-wise variation of load. The study results opened the possibility to reliably determine how the rotation frequency of a piston engine with RFSS deviates in response to a step-like change of load. This quantity uniquely determines deviation of the frequency of voltage generated by the electrical generator driven by such engine. The authors have created prerequisites for determining the advisable application field of piston engines with RFSS in cogeneration power supply systems.

Cascades of alternating pitchfork and flip bifurcations in H-bridge inverters

Power electronic DC/AC converters (inverters) play an important role in modern power engineering. These systems are also of considerable theoretical interest because their dynamics is influenced by the presence of two vastly different forcing frequencies. As a consequence, inverter systems may be modeled in terms of piecewise smooth maps with an extremely high number of switching manifolds. We have recently shown that models of this type can demonstrate a complicated bifurcation structure associated with the occurrence of border collisions. Considering the example of a PWM H-bridge single-phase inverter, the present paper discusses a number of unusual phenomena that can occur in piecewise smooth maps with a very large number of switching manifolds. We show in particular how smooth (pitchfork and flip) bifurcations may form a macroscopic pattern that stretches across the overall bifurcation structure. We explain the observed bifurcation phenomena, show under which conditions they occur, and describe them quantitatively by means of an analytic approximation.

Advanced technology of transformer winding condition control based on nanosecond probing impulse

One of the prospects of resource-effective technologies in power industry is control of electric equipment condition. Effectiveness of any electrical energy system strongly depends on stable work of power supply equipment. It, in turn, is defined by timely and reliable control of equipment condition. Power transformers are the key element of an electrical energy system.Winding defects caused by short circuit currents are the reason for an emergency situation. Reliable control of winding condition is an urgent task of modern power engineering technology. This paper deals with the experimental research of pulsed method of transformer winding control. A new approach to the winding condition control technology is described. The proposed method is based on short nanosecond range (compared to typical pulsed technology) probing impulse andfront impulse durations. Experimental results of sensitivity growth at the nanosecond probing impulse duration are shown. Experimental equipment and measurements are described. Comparison of experimental results of the proposed pulsed method and FRA is given. It is shown that probing impulse of nanosecond duration allows upgrading sensitivity of diagnostics procedure. The main proposals are confirmed by measurement results obtained in the electric energy system transformer for different types of winding defects.

Advanced technology of transformer winding condition control based on nanosecond probing impulse

Abstract One of the prospects of resource-effective technologies in power industry is control of electric equipment condition. Effectiveness of any electrical energy system strongly depends on stable work of power supply equipment. It, in turn, is defined by timely and reliable control of equipment condition. Power transformers are the key element of an electrical energy system. Winding defects caused by short circuit currents are the reason for an emergency situation. Reliable control of winding condition is an urgent task of modern power engineering technology. This paper deals with the experimental research of pulsed method of transformer winding control. A new approach to the winding condition control technology is described. The proposed method is based on short nanosecond range (compared to typical pulsed technology) probing impulse and front impulse durations. Experimental results of sensitivity growth at the nanosecond probing impulse duration are shown. Experimental equipment and measurements are described. Comparison of experimental results of the proposed pulsed method and FRA is given. It is shown that probing impulse of nanosecond duration allows upgrading sensitivity of diagnostics procedure. The main proposals are confirmed by measurement results obtained in the electric energy system transformer for different types of winding defects.

A Comparative Analysis of Technologies for Covering Peak Loads in the Power System

One of the key and so far completely unsolved problem of modern power engineering is minimizing the cost of compensating for the imbalance between the generated and consumed powers in power systems. In addition to traditional regulation methods using hydroelectric and thermal power plants, the possibilities of storing power in different forms, including stationary electrochemical storage systems, are being more and more widely used at present. It is planned in future to use the on-board storage batteries of electric vehicles (V2G technology) for this purpose. Traditional and promising future technologies for compensating load fluctuations in electric power systems have their own niche applications and costs under different operating conditions. In this paper we provide comparative estimates of the specific costs when compensating load fluctuations of different duration using traditional technologies, which use flexible power units and peak power plants, and also technologies based on the use of electrochemical electric power storage. The costs for 1 kW h of peak electric power and the costs in theory per 1 kW of peak power are estimated. As follows from the results of the calculations, the use of electrochemical storage is economically useful for continuous operating times of less than 1 h. To cover longer electric consumption fluctuations, the most suitable technologies remain flexible gas turbine systems and simple-cycle and gas-piston equipment under peak conditions.

Development of pulsed method for diagnostics of transformer windings based on short probe impulse

Insulation destruction is one of many failure reasons of power transformers which belong to the most expensive and strategically important components of any electrical energy system. Insulation damage due to short circuit currents can cause an emergency situation at any moment. Thus, the reliable control of winding state is an important task of a modern power engineering technology. The paper deals with the experimental research of the pulsed method of transformer winding control. A new approach to winding state control technology is described. The proposed method is based on short (compared with a typical pulsed technology) probe pulse and front pulse durations. The experimental results of sensitivity growth at decreasing front pulse duration are shown. The experimental equipment and measurements are described. A comparison of the experimental results of the proposed pulsed method and FRA is given. It is shown that shorter front of probe pulse duration allows upgrading sensitivity of the diagnostic procedure.

Thermophysical properties of the products of low-grade fuels thermal recycling

The relevance of the work is caused by reorientation of the modern power engineering to use of local low grade fuel resources. Some types of low grade fuels (peat, brown coal, sapropel, wood chips) are considered in this work. Thermotechnical characteristics of the investigated fuels and products of their thermal recycling are determined. Thermal recycling process is accompanied by release of fuel dissociation heat (0.33-3.69 MJ/kg). The results of thermal low grade fuel recycling are solid carbonaceous product (semi-coke) with a calorific value higher in 1.5-7 times than the value of natural fuels; pyrolysis resin with calorific value 29.4-36.8 MJ/kg; combustible gas with calorific value 15.16-19.06 MJ/m3.

Development of a Power Systems Protection Laboratory through University-Industry Partnership

At the 2007 National Science Foundation workshop on ‘The Future Power Engineering Workforce’ participants from US government, academia, and the private sector discussed the looming shortage of power engineering graduates to replace large numbers of projected retirees in the power engineering sector. The group identified the key drivers of this shortage and suggested a series of measures which, if implemented, would add to the ongoing renaissance in power engineering. Some of these measures have been adopted and reflected in the development of a power system protection lab at Penn State Harrisburg. With the support of local utility industry a new lab has been developed that integrates the latest devices and software in the electric utility industry into power systems courses. Instructional modules on key aspects of the new lab are developed to assist both the course instructor and future students enrolled in Power Systems Analysis courses. This paper outlines the facilitation and design process in the development of a modern power engineering laboratory.

Energy saving at operation of outdoor swimming pools

Purpose. Energy saving is a major problem in modern power engineering and various energy-consuming devices. They include outdoor swimming pools. In order to maintain them in working condition, especially in winter period, it takes significant amount of thermal energy. Task of heat loss substantial decrease in open swimming pools is considered in the article (on DNURT example). Methodology. The method of determining the mass and heat loss on the basis of criteria equations of heat and mass transfer theory is used. Findings. Calculations of the actual DNURT pool heat loss for different seasons, as for natural convection both for air forced motion above the free water surface are performed. It is shown that for the adiabatic evaporation conditions of water from the pool in winter during blow-off with wind the heat loss can be up to 2 kW/m2 on surface. To reduce these losses it is offered to cover water surface in a pool with a special material with low thermal conductivity on the basis of porous polyethylene during the time when the pool is not used for other purposes. It is shown that the implementation of these standards will reduce the actual heat loss, at least 5-6 times. Originality. The solution of important environmental and energy problem thanks to reducing heat losses by the pool in different times of a year and correspondingly lower emissions of power generating enterprises. Practical value. It is shown that the coating surface of the pool with poorly heat-conducting and easy to install coating will let, at a minimum, to reduce the actual heat loss on 5-6 times and reduce the emissions of power plants generating energy for pool heating.

An approach to modeling and thermodynamic analysis of modern power engineering systems

An approach to modeling and thermodynamic analysis of modern power engineering systemsThe new efficient method of modeling and thermodynamic analysis of power engineering systems has been presented. With its help a comparison of different structures and investigation of the influence of a particular constituent process onto the whole system efficiency is possible. The shaft work or the exergy is the main thermodynamic quantity taken into account in analyses, and the appropriate dimensionless modeling parameter has been introduced.

Radiation swelling of modified austenitic steels

Problems of synthesis of radiation-resistant austenitic steels for nuclear reactors now in operation and those of new generations to be used in future are considered. An analysis of the state-of-the-art and prospect for solving this problem demonstrates that, despite significant efforts of researchers all over the world, the economically required levels of operation of nuclear reactors have not yet been achieved. This is determined to a large extent by the insufficient radiation resistance of the main structural materials, namely, of corrosion-resistant austenitic steels. The main problem of supplying materials for modern nuclear power engineering and that to be used in future is a study of microstructural evolution and its influence on degradation of the initial physical-mechanical characteristics. The influence of the structural state of alloyed steels on the radiation resistance is examined.

Electric power quality: a tutorial introduction

Electric power quality is an aspect of power engineering that has been with us since the inception of power systems; however, topics in power quality have risen to the forefront since the advent of high power semiconductor switches and networking of transmission and subtransmission systems. Also, the trends in modern power engineering have been to extract the most from the existing installed power system, and this too has placed stress on issues of sinusoidal waveform fidelity, absence of high and low voltage conditions and other AC waveform distortion. A tutorial introduction to the concepts of electric power quality is presented in this paper.