Electrical Operation Mode Research Articles

Enhancing the efficacy of humidifier-dehumidifier desalination in humid regions through the use of an absorption refrigeration cycle (an economic and experimental investigation)

This experimental study investigates the performance of a novel humidifier-dehumidifier (HDH) desalination system integrated with a vapor absorption refrigerator (VAR) and photovoltaic (PV) panels for humid regions. The effects of air mass flow rate (m˙a) and inlet air temperature on key performance indicators were evaluated. Increasing m˙afrom 0.0039 kg/s to 0.0071 kg/s led to a 73 % increase in freshwater output, a 35 % increase in Coefficient of Performance (COP), a 100 % increase in Gain of Output Ratio (GOR), and a 75 % increase in Recovery Ratio (RR), but a 20 % decrease in dehumidifier efficiency. The maximum freshwater production rate of 870 g/h and a GOR of 1.4 were obtained at m˙a= 0.0071 kg/s and inlet air temperature of 50 °C, representing a 117 % increase compared to the lowest temperature and flow rate tested. The cost of freshwater for solar and electric operation modes was 0.075 and 0.094 USD/kg, respectively. The system's novelty lies in the integration of HDH desalination with a VAR and PV system, enabling continuous freshwater production even under cloudy or nighttime conditions. The findings demonstrate the potential of the proposed system for sustainable freshwater production in humid areas.

Dual-input optoelectronic synaptic transistor based on amorphous ZnAlSnO for multi-target neuromorphic simulation

Optoelectronic synapses can perceive both optical and electrical signals, which are critical for the realization of neuromorphic computing. We have rationally designed an optoelectronic synaptic transistor based on amorphous ZnAlSnO for multi-target neuromorphic simulation and recognition. The dual-input models are well operated by applying light pulses on the channel and electric pulses on the gate, and the transformation from short-term potentiation (STP) to long-turn potentiation (LTP) is identified for tunable synaptic plasticity. In the electrical operation mode, a single-layer artificial neural network was established to recognize handwritten digits by LTP/LTD (long-turn depression) modulation, with a recognition accuracy of 89.2 % for the actual device. In the optical operation mode, the processes of repetitive learning, image recognition, and biased/correlated random-walk learning are simulated on the basis of frequency, quantity, and power of light, with an energy consumption per event as low as 4.3 pJ. This work will facilitate the development of future artificial synapses and highlights the potential of amorphous oxide semiconductors for next-generation computer hardware applications.

Emission characteristics and removal of heavy metals in flue gas: a case study in waste incineration and coal-fired power plants.

Heavy metal pollutants such as Hg, As, Pb, Cr, and Cd emitted from coal and waste combustion have received widespread attention. In this study, we systematically investigated the emission characteristics of heavy metals in waste incineration and coal-fired flue gases, focused on testing the removal effect of self-made cold electrode electrostatic precipitator (CE-ESP) on heavy metals in flue gas, and made a comparative analysis with the existing air pollution control devices (APCDs). Test results from waste incineration power plant showed that each APCD showed a certain effect on the removal of heavy metals in condensable particulate matter (CPM), with an average removal efficiency of bag filter was 86%, but its effect on Hg removal was slightly worse. Under the coupled field with electrified cold electrode plate operation mode, the average removal efficiency of CE-ESP on heavy metals in CPM was as high as 93%, including 76% for Hg. The removal efficiency of heavy metals (especially Hg) in CPM increased with the increase of flue gas temperature difference between inlet and outlet of CE-ESP. Test results from this coal-fired power plant showed that heavy metals were enriched in fly ash to a higher degree than in slag, the synergistic control of heavy metals in submicron particulate matter by the dust remover was not obvious, and there was a significant correlation between each heavy metal emission factor and its content in coal. Under the temperature field with non-electric cold electrode plate operation mode, the overall effect of CE-ESP on the removal of gaseous heavy metals was better than that of particulate heavy metals. Under the conventional electric field operation mode, CE-ESP was less effective in removing particulate Cr and gaseous Hg0. Under the coupled field with electrified cold electrode plate operation mode, the average removal efficiencies of CE-ESP for particulate and gaseous heavy metals were 82.37% and 76.16%, respectively.

Application of Variable Frequency Speed Regulation Technology in Industrial Electrical Automation Control

Before the emergence of frequency conversion speed regulation technology, the industrial electrical automation operation mode has been realized, but in the early operation, the operation mechanism of the automatic control system is relatively simple, that is, according to the unified logic, the start and stop control of electrical equipment, this mode can mainly play a reasonable allocation of electrical equipment operating time and reduce the failure rate of equipment in practical work. However, the simple start-stop control mechanism will affect the capacity level of industrial units, which shows that there are defects in early automation control. So in the context of modern technology, some scholars have proposed the application of frequency conversion speed regulation technology in automatic control, refining the startstop control mechanism to ensure the "relative maximum production capacity" as much as possible, while taking into account the energy efficiency of reducing the failure rate.

Electric Network Operation Mode Optimization According to the Minimum Active Power Loss Criterion

Electric Network Operation Mode Optimization According to the Minimum Active Power Loss Criterion

Free nitrous acid-assisted asymmetrical alternating current electrochemistry (FNA-AACE) for multi-heavy metals decontamination in waste activated sludge

Heavy metal contamination of waste activated sludge (WAS) is a key factor limiting the land application of sludge for nutrients recovery. This study proposes a novel free nitrous acid (FNA)-assisted asymmetrical alternating current electrochemistry (FNA-AACE) process to achieve high-efficiency decontamination of multi-heavy metals (Cd, Pb, and Fe) in WAS. The optimal operating conditions, the heavy metal removal performance of FNA-AACE, and the related mechanisms for maintaining the high performance were systematically investigated. During the FNA-AACE process, FNA treatment was optimal with an exposure time of 13 h at a pH of 2.9 and an FNA concentration of 0.6 mg/g TSS. Then the sludge was washed with EDTA in a recirculating leaching system under asymmetrical alternating current electrochemistry (AACE). The 6-h working and the following electrode cleaning were defined as a working circle of AACE. After three cycles of working-cleaning periods in AACE treatment, the cumulative removal efficiency of the toxic metals Cd and Pb reached over 97% and 93%, respectively, whilst that of Fe was greater than 65%. This surpasses most previously reported efficiencies and possesses a shorter treatment duration and sustainable EDTA circulation. The mechanism analysis suggested that FNA pretreatment provoked the migration of heavy metals for leaching enhancement, as well as reduced the demand for EDTA eluent concentration and increased conductivity, which can improve the AACE efficiency. Meanwhile, the AACE process absorbed the anionic chelates of heavy metals and reduced them to zero-valent particles on the electrode, regenerating the EDTA eluent and maintaining its high extraction efficiency for heavy metals. In addition, FNA-AACE could provide different electric field operation modes, allowing it to have flexibility for the real application processes. This proposed process is expected to be coupled with anaerobic digestion in wastewater treatment plants (WWTPs) for high efficiency of heavy metal decontamination, sludge reduction, and resource/energy recovery.

On the Influence of Organizational and Technical Measures on the Cascade Evolvement of Accidents in Electric Power Systems with Heterogeneous Parameters

The aim of the study is to assess the effect of various organizational and technical measures on the evolvement of emergency cascade processes in electric power systems (EPS) with heterogeneous parameters and to determine the limits of the maximum permissible operation modes. The article presents the results of electrical operation mode calculations in the test configurations of 6, 35, 110, and 500 kV EPS containing 25, 36 and 40 nodes, which illustrate the influence of heterogeneity of the EPS parameters on the evolvement of cascade emergency processes. An approach to taking into account the heterogeneity of EPS parameters in planning and maintaining the EPS operation modes is presented. To enhance the EPS survivability and reduce the risk of cascade emergency processes to occur and evolve, distributed generation facilities of different capacities and FACTS devices were used in the EPS. In addition, power flows were redistributed by changing the loading of existing power plants with different electricity generation costs. The proposed approach was used to analyze the evolvement of a cascade-type system accident that occurred in the EPS of the Republic of Bashkortostan. By using the developed approach, the possibility of cascade emergency processes to occur and evolve can be evaluated in planning and maintaining the EPC operation modes, as well as to develop EPS configuration and operation mode adjustment measures aimed at preventing such emergencies from occurring.

Intelligent Electrical Engineering Automation on Account of Particle Swarm Optimization (PSO) Algorithm

Electrical engineering is closely related to people’s life. Many projects have proved that electrical engineering using PSO algorithm provides more convenient applications for people’s production and life, greatly improves people’s living standards, and makes people’s life and work more relaxed and valid. In many production fields, such as subway engineering, if advanced electrical engineering automation is adopted, the subway engineering can be carried out validly from start to finish, and the workload of workers can be greatly reduced. PSO algorithm further improves the automation performance of electrical engineering, and effectively breaks through the traditional electrical engineering operation mode, improve the operation efficiency. This text studies the concept and work flow of PSO algorithm, introduces the intelligent working principle and internal mechanism of electrical engineering. Data analysis, intelligent electrical engineering automation on account of PSO algorithm effectively improve the intelligent effect of electrical engineering automation.

The effect of complex load on the reliable operation of solar photovoltaic and wind power stations integrated into energy systems and into off-grid energy areas

A mass renewable power stations commissioning, first of all solar photovoltaic stations (SPVS) and wind power stations (WPS) shall be associated with the properly implemented complex load modeling while calculating their electric operation modes. This article deals with the basic failures of standard algorithm of SPVS and WPS invertors/converters, Fault Ride Through (FRT), that has to reduce the active power output and to increase that of reactive power, in case of voltage drop. In order to prevent outages of SPVS and WPS equipment during emergency disturbances, the trip set points of SPVS and WPS inventors/converters shall be adjusted to those of the adjacent power network protective relay. In this article, an approach to selecting methods for complex loads modeling, in industrial energy areas, has been developed. A method for calculating the value of critical voltage across the load bars has been considered, and the relevancy to apply the dynamic scale model of electric motor has been substantiated. The specific aspects of the voltage-dependent and frequency-dependent load static characteristics employment, in calculations of electromechanical transient processes, have been analyzed. Recommendations on representing electric motors integrated into complex load circuits, in various software packages designed for operation modes calculations, have been stipulated. Various methods making it possible to take account of electromagnetic transient processes, in rotors of asynchronous motors, have been described. A proper account of complex loads enables to ensure reliable functioning of SPVS and WPS integrated into energy systems and operating in isolated energy areas avoiding their outages including those disturbances in power supply of power consuming equipment of industrial areas.

Определение рациональных электрических режимов промышленных дуговых сталеплавильных печей

The choice of a rational electrical mode of existing or newly commissioned electric arc furnaces (EAFs) is a very difficult task for process engineers in view of the influence of external disturbing factors. Based on an electric arc heat-transfer model (EAHTM), a method is proposed, using which the problem of determining the optimal electrical operation mode can be solved with the minimal number of simplifications and assumptions, and with taking into account the specific features of a particular EAF. In solving the problem, the following factors are taken into account: the arc heat transfer conditions in the melting space; the influence of the thermal operation conditions of the electrodes and the arc length on the structure of heat fluxes during the heating by arcs, and the effect the chemical composition of the working medium has on the thermophysical properties of the arc column plasma. The radiation from EAF arcs with taking into account the column temperature profile is calculated using the method of universal arc characteristics based on the solution of a system of nonlinear algebraic equations of the EAHTM column cylindrical model. The arc length calculation is based on the EAHTM structural characteristics method and consists of comparing the arc voltage value calculated using the furnace equivalent circuit equation and the arc voltage calculated using the EAHTM. Knowing the arc length, it is possible to calculate the arc radiation power in the EAF melting space. The choice of an electrical operation mode implies specifying an electrical parameter to be maintained by the controller for a certain period of melting. The value of this parameter (arc current or the EAF phase loop impedance) governs the other electrical parameters of the electric furnace installation, such as arc power, electrical losses, power factors, efficiency, etc. In addition, the correct choice of the electrical operation mode has an influence on other important operational characteristics, such as the specific consumption of electrodes, the duration of the interval between repairs, etc.

Расчет параметров режима электрической сети с учетом изменяющегося реактивного сопротивления фазосдвигающего трансформатора

The aim of the work is to study the effect the variation of the phase-shifting transformer (PST) reactance has on the accuracy of calculating its control angle and the electrical network operating parameters obtained as a result of this control. The operating parameters, in particular, active power flows in the electrical circuit branches, are controlled by changing the PST angle; however, in view of the PST design features, this control entails a change of its reactance. Depending on the design features of different PST models and the control angle value, the PST reactance may be constant or vary in a significant range. In connection with a growing use of PSTs in industrially developed countries and with the fact that the first samples of this equipment have emerged in the CIS countries, including Russia, an increased attention is paid to this topic in a number of domestic and foreign publications. In particular, matters concerned with the stability of electric operation modes are considered in view of the fact that the PST reactance depends on its control angle, and the effect this dependence has on the operating parameters is estimated. The necessity of taking into account the varying PST reactance in calculating its control angle for controlling active power flows is considered for different cases. Forced redistribution of active power flows in the closed loops of an electrical network by means of a PST can be used to reduce active power losses and to maintain the required loading of the power lines for various reasons, for example, for commercial purposes or in the case of transit power flows between different countries. In view of the complexity of calculations, constant values of the PST reactance are usually assumed, but this approach is valid not for all types of PST designs. In the majority of PSTs, their reactance varies with increasing the control angle. Therefore, calculations carried out without taking this feature into account may yield a fortiori incorrect correspondence between the control angle and the transformer reactance value. In turn, an error will be introduced in the accuracy of the PST control angle calculations, as well as in the calculations of the operating parameters that should be obtained from the control action.

All-electrical switching and electrothermo-optical response of a tristable smectic-A liquid crystal

A unique switching mechanism in the smectic-A (SmA*) phase involving textural change between any two among the planar, homeotropic and focal conic states is investigated. Exploiting the temperature-dependent textural transition characteristics of a SmA* liquid crystal (LC), we proposed a multi-stable switching scheme relying on AC voltage to induce the dielectric effect and pseudo-dielectric heating. This mechanism exhibits desirable properties for LC cells with anti-parallel planar surface treatment. Compared with the electrical operation mode of conventional SmA devices, the optical states enabled by this approach show superior qualities in both transmittance and haze value. The revealed features, including the in-phase switching, tunable operating temperature and excellent optical performance, show great potential for applications in smart glass and other energy-saving devices.

The Influence Of The Led Luminaires Electrical Parameters On Their Correlated Colour Temperature During Operation Mode

The article describes the results of comprehensive study aiming at increase of quality of LED luminaires and definition of the nature of changes in their correlated colour temperature (CCT) in the course of operation. Dependences of CCT of LED luminaires with remote and close location of phosphor for 10 thousand hours of operation in different electric modes were obtained; the results of comparison between the initial and final radiation spectra of the luminaires are presented; using mathematical statistics methods, variation of luminaire CCT over the service period claimed by the manufacturer is forecast; the least favourable electric operation modes with the highest CCT variation observed are defined. The obtained results have confirmed availability of the problem of variation of CCT of LED luminaires during their operation. Possible way of its resolution is application of more qualitative and therefore expensive LEDs with close proximity of phosphor or LEDs with remote phosphor. The article may be interesting both for manufacturers and consumers of LED light sources and lighting devices using them.

Electric vehicle operation modes with reactive power support using SMC in distribution generation

In this work, a single phase 120 V rms, 60 Hz on-board Electric Vehicle (EV) battery charger with capacity 100 Ah for operation in Grid to Vehicle (G2V) and Vehicle to Grid (V2G) with Reactive Power Support using Sliding Mode Controller (SMC) is presented. The controller is chosen for its robustness and steady tracking precision. State space models of G2V and V2G of EV are derived and good stability margins are obtained using frequency response characteristics. SMC is found to be good in tracking the dc voltage in G2V and grid current in V2G with less steady state error. THD in grid current is 0.645 % during G2V and 1.95 % in V2G which are comparatively less than in Proportional plus Integral (PI) and Proportional plus Resonant (PR) controllers. Dynamic nature of SMC is found to be robust during grid frequency variations. It delivers less steady state error of 1.52 % and settling time of 0.1 s during charging and discharging operations. Phase planes are presented to understand finite convergence of SMC. Reactive power support to the grid operation is presented without affecting the state of charge (SOC) of the battery. Solar based charging circuit is discussed for EV charging. The SOC depicts changeover state from normal to solar charging reaching 100% within short period. SMC was designed to be robust against bounded perturbations and also guarantee stability and finite convergence. PSCAD v4.6 software is used.

ПРИМЕНЕНИЕ ЧИСЛЕННОГО МОДЕЛИРОВАНИЯ ДЛЯ ОЦЕНКИ ЭЛЕКТРОТЕПЛОВЫХ РЕЖИМОВ РАБОТЫ ЭЛЕМЕНТОВ КОНТАКТНОЙ СЕТИ ПОСТОЯННОГО ТОКА

The paper proposes a method for assessing electric and thermal operation modes of direct current catenary elements that allows determining electric and thermal loads in operation conditions. The main principle is the determination of the most loaded section in the intersubstational zone and calculation of electric and thermal characteristics in conditions of real train schedule. The method is assumed to be used at digitalization of railways as a digital copy of direct current catenary.

Neural Network Identification of Operating Modes of a Robotic Platform Electric Drive

This paper considers an approach to identifying electric motor operation modes by means of neural networks. It is shown that the amplitude–frequency response (AFR) of current in the motor windings can serve to achieve this goal. The two neural network models that are proposed cover AFR approximation and mode identification, respectively. Potential emergency situations are considered that can be identified using the suggested approach. The proposed neural network is taught to recognize these situations by the current consumption characteristics of the platform’s motors. It is shown that a motor’s running mode affects the wave characteristics of its windings, which allows creating a model to identify the motor’s running mode by measuring the values associated with the processes in the windings.

Гибридная трехфазно-однолинейная режимная модель для оценки состояния электроэнергетической системы

The article considers a new formulation of the state estimation problem, i.e., calculating the electric power system operation mode based on remote measurement data. The suggested approach implies the possibility of computing the electric operation mode parameters in a three-phase formulation for the grid parts equipped with three-phase measurement instruments. As regards the grid parts that are not fitted with such instrumentation, but in which single-line measurements are available, or which are characterized by an insignificant imbalance of operation mode parameters, their state is estimated in the single-line formulation. A distinguishing feature of such problem formulation is that the AC power flows in the grid circuit branches are used as the sought variables. The use of this approach essentially simplifies the problem and brings about additional advantages that are especially important for distribution networks. A hybrid three-phase and single-line operation mode analysis model for solving the state estimation problem is proposed and described. Owing to the use of AC power flows in the grid circuit branches as independent variables (a flow model), it becomes possible to use the phase or line form of the described model depending on the available measurement information in the grid part or component and the requirements posed to the problem being solved. The change over from one system of coordinates to another is made without making essential changes in the analysis model itself. The model errors were analyzed on a test network circuit. The analysis results have shown that the proposed model can be used for calculating the electric operation mode if the phase voltages at the interface between the three-phase and single-line grid submodels do not differ from each other by more than 10%.

Прогнозирование энергопотребления в период плавки шихты в дуговых сталеплавильных печах

A solution to the problem of selecting the operating arc current at which the minimum amount of electricity is consumed for melting the furnace charge with the specified parameters of the steelmaking electric arc furnace (EAF) equivalent circuit is proposed based on the developed methods of universal and structural characteristics of the arc heat-transfer model (AHTM) is proposed. In solving the problem, the following factors were taken in consideration: the arc heat-transfer conditions in the melting space, the influence of the electrode thermal operation conditions, the influence of arc length on the heat flux structure in heating the charge by arcs, and the effect the chemical composition of working medium has on the thermophysical characteristics of the arc column plasma. The main specific feature of heating by arcs in the EAF melting space is a complex pattern of furnace charge heating due to radiation from arcs and convection as a result of plasma motion in the arc columns. The wide variation range of the ratio of the radiation power to the power transferred by convection has an effect on the furnace charge melting rate and on the amount of electricity consumed in the course of melting. The furnace charge melting intensity depends to a significant extent on the arc radiation power level. The radiation from EAF arcs was numerically analyzed with due regard to the column temperature profile using the arc universal characteristics method by solving the system of nonlinear algebraic equations of the column cylindrical model (ATHM). The arc length is calculated using the ATHM structural characteristics method and consists in comparing the arc voltage calculated from the furnace equivalent circuit equation with the arc voltage calculated using the ATHM. Knowing arc length, it is possible to calculate the arc radiation power in the EAF melting space. After calculating the arc radiation power performance characteristic and the furnace useful power characteristic according to the proposed technique, it is possible to predict the amount of electricity consumed for melting the solid furnace charge and the time of its melting with the furnace being energized. The calculated values of the solid furnace charge melting time for small- and large-capacity EAFs during their energized operation show good agreement with the experimental data. The proposed method for predicting the specific consumption of electricity for melting solid furnace charge in arc furnaces opens the possibility to select — in developing the EAC electric operation mode and in adjusting its operation---the arc operating current at which the maximum solid furnace charge melting rate is achieved and, thereby, to achieve a smaller consumption of electricity in the furnace operating cycle.

Emulations of synaptic plasticity in the planar transistor configuration for neuromorphic computing

Due to the expansion of data information, computers based on the traditional von Neumann architecture have been unable to store or flexibly handle large amounts of information. Compared to this, the highly parallel nonlinear information processing the capability of brain reveals an attractive advantage, which is considered as the target of computing development. The human brain is composed of neuronal networks which are connected by 10 14 –10 15 synapses. Synapses are the connection channels for the exchange of information between neurons, characterized by synaptic plasticity. Synaptic plasticity functions play a crucial role in the transmission of neural signals in the brain and it is the molecular basis of biological learning and memory. In order to emulate neuronal networks, it is essential to design a physical device possessing the functions of biological synapses, so that the neuromorphic circuits which can functionally emulate the brain-like behaviors can be realized. The transdisciplinary researches integrated the novel insights of neuroscience, physics, chemistry, materials science and engineering are performed. Researchers have shown that in the transistor structure with adjustive memristive characteristics, considered as the signal transmission and regulation modules, the conductive channel and gate function are analogous to ionic conduction and neurotransmitter release process in the biological synapse, respectively. In most researches, voltage pulses applied on the gate electrodes are used to simulate the presynaptic spikes or external stimuli, the channel conductance is considered as synaptic weight. So the simulation of biological synapses can be realized in such field effect transistors. Meanwhile, as a considerably popular platform with memory effect, the electron-type transistor memory which is designed for binary data storage is fabricated characterized by gentle process of charge trapping, where the relaxation tendencies of OFF (ON) state in electrical operation mode can be utilized to simulate the biological facilitating (depressing) activities, respectively. So, we can emulate the functions of biological synapses in the electron-type transistor memory, too. In this paper, recent simulations of synaptic plasticity functions in transistor synapses with planar structures are summarized, including short-term synaptic plasticity (such as paired-pulse facilitation and inhibition, dynamic filtering (high-pass filtering/low-pass filtering), spatiotemporally correlated signal processing, adaptation, etc), long-term synaptic plasticity, and the transition between them, spike-timing-dependent plasticity, shunting inhibition, and so on. The characteristics and different simulation methods of these functions are illustrated, the mechanisms and advantages of the planar transistor configuration are explained, current weaknesses and challenges of transistor synapses are pointed out, the future development in this field are also prospected.

Experimental study on heating characteristics and control strategies of ground source heat pump and radiant floor heating system in an office building

In building energy consumption, the proportion of heating in energy consumption is very large. From the point of view of energy saving and thermal comfort, radiant floor heating system needs to be popularized and applied. This study takes the ground source heat pump and radiant floor heating system of an energy-saving demonstration building as the experimental plat-form. The indoor temperature of the operating system is obtained by the instrument at different heights. Indoor temperature fluctuation and distribution and the heating characteristics of the system can be obtained. Results show that the indoor temperature of the heating system meets human thermal comfort, and the indoor temperature of room which receives the solar radiation can still be maintained more than 18 °C in work time within two days when the sys-tem is closed. Moreover, valley electric operation and storage tank system operation mode makes the ground source heat pump and radiant floor heating system more efficient. The sys-tem is worth widely being used.