Power Balance Method Research Articles

Investigating the Sommerfeld effect in the rotating shaft with internal and external damping using the Timoshenko beam theory

The Sommerfeld effect is a destructive phenomenon in rotating systems with a non-ideal electrical source, which causes instability in the system by applying a dynamic jump around critical speeds. In this article, the Sommerfeld effect has been investigated for the first time using the Timoshenko beam theory for an eccentric continuous shaft with internal and external damping. After deriving the governing equations and finding displacement functions using the semi-analytical method, the Sommerfeld effect near the critical speeds is detected using the instantaneous power balance method. As confirmation of the correctness of the derived relations, it has been shown that for thin shafts, there is a good consistency between the results obtained from the Euler–Bernoulli and Timoshenko theories in the early modes. However, it was observed that at higher critical speeds, the jump amplitude decreases, and the unstable speed range increases significantly, so the probability of entering the vicinity of the instability range in the next mode is not unexpected. Since no effect has been ignored in this study, the dynamic analysis of the Sommerfeld jump in thick shafts is also possible. Despite the common belief that Timoshenko beam theory is only considered suitable for studying thick shafts, it has been shown that the effects of shear deformation are significant in high-speed systems, even for non-thick shafts, and regardless of them in higher modes, it causes a calculation error in determining the point of occurrence of the Sommerfeld phenomenon.

Potential for Energy Recovery from Boundary-Layer Ingesting Actuator Disk Propulsion

The theoretical benefits of highly integrated propulsion systems are highlighted herein by assessing the potential for energy recovery utilization using actuator disk propulsion. Decomposing aerodynamic forces into thrust and drag for closely integrated bodies, particularly those employing boundary-layer ingestion, becomes challenging. In this work, a mechanical energy-based approach was taken using the power balance method. This allowed the performance to be analyzed through the mechanical flow power in the fluid domain, disregarding the need for any explicit definition of thrust and drag. Through this, the benefit of boundary-layer ingestion was observed from a wake energy perspective as a decrease in the downstream mechanical energy deposition and associated viscous dissipation. From a propulsion perspective, the reduction in power demand necessary to produce propulsive force indicated the possibility of power savings by utilizing the energy contained within the ingested boundary-layer flow.

A Current and Output Power Balance Method Applied in IPT System with Multiple Parallel Pickup Modules for Rail Transit

A Current and Output Power Balance Method Applied in IPT System with Multiple Parallel Pickup Modules for Rail Transit

Distribution Network Balance Method under High Proportion of Distributed Power Penetration Scenario

With the rapid development of various subjects represented by distributed generation, how to implement power balance in a distribution network has become a research direction. The utilization efficiency of a distribution network can be improved by the bidirectional power flow of flexible resources. However, the traditional distribution network power balance method relies on historical data, making it challenging to determine the principle of new subject participation. It does not meet the requirements of bidirectional power flow balance and loses critical information such as complementary load characteristics. We believe that distribution network power prediction needs to transform from single load prediction to multi-resource prediction, from quantitative prediction to quantitative plus characteristic prediction. In comparison to the traditional methods, curve superposition can be better compatible with the research results of different new load forecasting topics and meet the needs of efficiency and precise network planning.

Kinematic analysis and synthesis of cutter movement of slotting machine

The kinematic characteristics of the links and individual points of the mechanism are determined by the method of closed geometric contours and the method of designing plans. The forces of interaction between the links of the mechanism are determined by the method of kinetostatics, and the balancing moment by considering the dynamic equilibrium of the crank and the method of power balance. The drawbacks of the structural scheme of the mechanism are revealed and the ways of their elimination are offered.
 The results of research are presented in the form of graphical dependences of the kinematic parameters of the cutter, reactions or hodographs of forces in kinematic pairs. The moments of resistance forces and inertia forces are determined and the dynamic and mathematical models of the movement of the mechanism are constructed. The technology of determining the power of the electric motor is shown, and its stable area of operation is approximated by a straight line.
 Kinematic synthesis was performed and a modernized mechanism was obtained in which the cutter can move according to a predetermined law, in particular, without soft shocks at the boundaries of the kinematic cycle and with quasi-constant speed (error up to 5%) in the middle of the kinematic cycle

Energy-Based Aerodynamic Analysis on the Blended-Wing-Body Aircraft with Boundary Layer Ingestion

This study is aimed at evaluating the energy saving benefit and its limitation of the boundary layer ingestion (BLI) applied to a transonic blended-wing-body (BWB) aircraft. The power balance method is adopted in the aerodynamic performance analysis of the aircraft. We further improve the one-dimensional analysis framework by adding the pressure volumetric work term in the power balance equation for the application in compressible flow with shock wave regions. A determining expression for the power-saving coefficient (PSC) of the BLI effect is also deduced, which is related to a BLI fraction, the airframe dissipation component ratios, and the specific thrust of the propulsor. This expression provides a way for the preliminary evaluation and comparison of BLI benefits applied in different aircraft configurations. The flow quantities of three different configurations are obtained by 3D Reynolds-averaged Navier–Stokes (RANS) numerical simulations for the calculation of aerodynamic dissipation components. The grid refinement and domain size study shows that the calculated force coefficients and total dissipation coefficient have a good convergence characteristic with the mesh refinement and are insensitive to the variation in domain size. The evaluated PSC of the BWB aircraft with a BLI propulsor is 5% using the previously developed determining expression. The maximum of PSC is 18.8%. The following comparison of dissipation components for the power-on and power-off cases shows that the benefit of BLI is slightly underestimated by the determining expression of PSC. The reason is that the variation in the boundary layer velocity profile at the trailing edge of the center body part is neglected, which is due to the installation of the propulsor. Furthermore, when the BLI propulsor is applied to a BWB aircraft, the variation in trailing edge vortex dissipation and volumetric pressure work term should be studied in detail.

An improved grid integration technique for SPV-based CHB-MLI in distribution network

The growing power electronics-based nonlinear load increases harmonic contribution in the power system leads to deterioration in the quality of power. The unbalance loading in three phase four wire (3P4W) system allows a neutral current flow, which is an escalating concern for the utility. In this paper, the instantaneous power balance method is employed for solar photovoltaic (SPV)-based nine-level cascaded H-bridge multilevel inverter (CHB-MLI). A modified instantaneous power balance method (PBT) is proposed for integrating SPV-based CHB-MLI with the arrangement specified here as solar photovoltaic shunt active power filter (SPV-SAPF). The zero sequence components have a significant effect on an unbalance 3P4W system, considered as a utility in this paper. FFT analysis done for different voltage levels of CHB-MLI shows that total harmonic distortion (THD) is within a permissible limit. Besides, simulation, experimental results are also provided to validate the performance of the proposed scheme.

Matematička i kompjuterska simulacija pojave udubljenja tokom hladnog kombinovanog izvlačenja

The article is considered a comparative analysis for predicting defect such as dimple by energy method of power balance, upper bound method and finite element method. The upper bound method takes into account the geometrical position and dimension of the dimple, the criterion for the formation in dimple by energy method of power balance is the presence of a minimum point in the function of relative pressure on the relative velocity of metal outflow in the vertical direction. New engineering calculations for the relative pressure are developed in combined radialbackward extrusion process by using a kinematic module with fillet. A comparative analysis of the obtained data has been carried out by energy method of power balance, upper bound method, computer simulation by Qform 2/3D program and experimental data. Rationality of using the energy method of power balance in view of its efficiency and the possibility of taking into account various friction conditions and the presence of fillet on the matrix, as well as smaller deviations from the results of finite element simulation and experimental data have been defined. Providing more conditions that are favorable for friction in the bottom of the billet and in the flange area in comparison with the friction conditions on the glass wall contribute to delay in the dimple appearance. It was found that the radius of fillet makes it possible to delay the dimple appearance by the approximately (0,4 ÷ 0.5R) mm for the entered radius of fillet R. This allows us to expand the possibilities of obtaining parts with a flange by combined radial-backward extrusion without the formation of a defect such as dimple.

A new modulation strategy and power balance method of unsymmetrical CHB inverter

There exist the problems of the low utilization rate of DC voltage, power imbalance and current backflow in the modulation process of traditional unsymmetrical cascaded units. In view of these, a pulse width modulation strategy with an improved trapezoidal wave as the modulation wave and its corresponding power balance method are proposed. First, through double Fourier analysis of the output line voltage, an appropriate sine coefficient δ is obtained. Second, the waveform of the modulation wave is determined according to δ. Third, through the simple logic operation of the initial driving signals of the switch transistors, the required switch driving signals are obtained, and the power balance of each unit with the same voltage level is realized. In order to verify the effectiveness of the strategy and the method, a simulation and experiment platform are built, and a large number of simulations and experiments are carried out. The results show that compared with the traditional sinusoidal modulation method, the utilization rate of DC voltage obtained by the method can be improved by 22.28% and compared with the trapezoidal wave modulation method, the waveform distortion coefficient of the output voltage can be significantly reduced, and the utilization rate of DC voltage can be further improved. Meanwhile, the power balance can be achieved within one voltage cycle and the phenomenon of current backflow is eliminated.

УДОСКОНАЛЕННЯ ПРОЕКТУВАННЯ ТЕХНОЛОГІЧНОГО ПРОЦЕСУ ТОЧНОГО ОБ’ЄМНОГО ШТАМПУВАННЯ ВИДАВЛЮВАННЯМ НА ОСНОВІ РОЗВИТКУ ЕНЕРГЕТИЧНОГО МЕТОДУ БАЛАНСУ ПОТУЖНОСТЕЙ

Improvement of technology design in precision forging process based on development of energy method with power balance and development of recommendation with the rational use of systematized based on kinematic modules in complex configuration to make calculated schemes for power mode assessments and shaping of part in cold forging extrusion process with subsequent software implementation are considered. Methodology. Energy method of power balance is considered based on kinematic module method that will be systematized the results of investigation for expanding in cold forging extrusion process with the definition of the power mode in deformation and features of semi-finished product shaping to make hollow and rod parts with flange such as sleeves and glasses. Results. Development results of recommendation with the rational use of systematized based on kinematic modules in complex configuration to make calculated schemes including with the ability to quickly take into account changes in the configuration of the tool have been determined. This made it possible to define the several factors for controlling the shaping of the semi-finished product in combined and sequential combined cold forging extrusion processes. Scientific novelty. Energy method of power balance is considered such as an effective method of preliminary analysis to determine the area of rational use in cold forging process based on process technology design to make complex parts. Practical significance. Software product development with extended systematization based on kinematic modules, complex of calculation models in cold forging extrusion with power mode assessments and to predict shaping of part and defect formation such as dimple defect will contribute more active implementation in the manufacturing industry for combined cold forging extrusion processes.

Potential for Energy Recovery of Unpowered Configurations Using Power Balance Method Computations

New aircraft developments are made to improve aircraft performance and efficiency. One such method is integrating propulsion into the airframe. This allows for boundary-layer ingestion, which shows promise of significant power benefits. However, these benefits are difficult to quantify as the propulsion system and aircraft body become meticulously integrated. The thrust and drag are coupled and cannot be defined separately, making conventional performance analysis methods inapplicable. The power balance method (PBM) addresses this by quantifying aircraft performance in terms of mechanical flow power and change in kinetic-energy rate. The primary focus of this work was to perform computational studies implementing the PBM on unpowered aerodynamic bodies to evaluate their respective drag contributions. A secondary study was also conducted to quantify the energy recovery potential of various bodies using a potential for energy recovery factor. The computational fluid dynamics case studies showed that drag obtained using the PBM agreed to within 2% of conventional momentum-based approaches. Maximal energy recovery potential was consistently observed at the trailing ends of the geometries, with values ranging between 9 and 12%.

Cold Atmospheric Pressure Plasma Technology for Modifying Polymers to Enhance Adhesion: A Critical Review

This review summarizes the results of cold atmospheric pressure plasma technology application in polymers surface treatment. Attention is given to results of changes in the hydrophilic property of polymer surfaces by incorporation of polar functional groups when exposed to atmospheric pressure plasma, depending on the time of treatment, applied voltage, gas flow rate, and distance from the surface. We have successfully developed a plasma device that is able to generate cold atmospheric pressure argon plasma of low temperature (20 – 26) ° C downstream using a high-voltage power source which can be widely used in materials processing. Therefore, a cost-effective system of generating a plasma jet at atmospheric pressure with potential applications has been developed. Cold atmospheric pressure plasma jet (CAPPJ) has shown a lot of applications in recent years such as in materials processing, surface modification, and biomedical materials processing. CAPPJ has been generated by a high voltage (0-20 kV) and high frequency (20-30 kHz) power supply.<br/> The discharge has been characterized by optical and electrical methods. In order to characterize cold atmospheric pressure argon plasma jet, its electron density, electron temperature, rotational temperature, and vibration temperature have been determined using the power balance method, intensity ratio method, Stark broadening method, and Boltzmann plot method, respectively. The improvement in hydrophilicity of the cold plasma-treated polymer samples was characterized by contact angle measurements, surface free energy analysis, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). Contact angle analysis showed that the discharge was effective in improving the wettability of polymers after the treatment. Furthermore, atmospheric plasma can be effectively used to remove surface contamination and to chemically modify different polymer surfaces. The chemical changes, especially oxidation and cross-linking, enhance the surface properties of the polymers.

Studi Kelayakan Water Pumped Energy Storage Sebagai Penyimpanan Energi PLTS Mandiri Pada Daerah Terisolir

Research and development on the implementation of renewable energy is growing rapidly, especially about photovoltaic (PV) and energy storage. Water pumped energy storage (WPES) is an alternative storage media in a standalone solar power system because of its longer technical life than chemical storage types, such as batteries. To assess the feasibility of WPES implementation as an energy storage in the standalone solar power plant system, the process of sizing the system components needs to be carried out by considering technical and economic aspects. This research will discuss the sizing process of standalone solar power system using WPES with closed loop reservoir systems and its economic analysis. The sizing process is carried out by the method of power balance, energy balance, and volume balance while economic viability is seen from the capital cost, O&M cost, and revenue from electrical energy absorbed by the load. In this study, the daily load profile with energy demand of 79 kWh and peak load of 4.36 kW. The analysis shows the need of 56 kWp PV system, 3800 m³reservoir capacity with 20m head. The calculation shows the technical efficiency of the system is 28.2%. From the economic analysis, the sistem’s payback period is 24 years, assuming the reservoir technical age is 50 years with net present value of Rp 2,072,823,731.86 and return of investment 105%.

Wireless power distributions in multi-cavity systems at high frequencies.

The next generations of wireless networks will work in frequency bands ranging from sub-6 GHz up to 100 GHz. Radio signal propagation differs here in several critical aspects from the behaviour in the microwave frequencies currently used. With wavelengths in the millimetre range (mmWave), both penetration loss and free-space path loss increase, while specular reflection will dominate over diffraction as an important propagation channel. Thus, current channel model protocols used for the generation of mobile networks and based on statistical parameter distributions obtained from measurements become insufficient due to the lack of deterministic information about the surroundings of the base station and the receiver-devices. These challenges call for new modelling tools for channel modelling which work in the short-wavelength/high-frequency limit and incorporate site-specific details—both indoors and outdoors. Typical high-frequency tools used in this context—besides purely statistical approaches—are based on ray-tracing techniques. Ray-tracing can become challenging when multiple reflections dominate. In this context, mesh-based energy flow methods have become popular in recent years. In this study, we compare the two approaches both in terms of accuracy and efficiency and benchmark them against traditional power balance methods.

Investigation on Parameters of Atmospheric Pressure Plasma Jet by Electrical and Optical Methods

The atmospheric pressure plasma jet works under atmospheric pressure condition, has been developed for surface treatment and biomedical applications. The produced jet has been characterized by electrical and optical methods. To characterize cold atmospheric argon plasma discharge, its electron density, and electron energy (temperature) at various conditions have been estimated by using different techniques such as power balance, stark broadening, and intensity ratio methods respectively. Atmospheric pressure plasma jet (APPJ) has drawn much attention all over the world due to its applications in material processing, biomedical material processing, and thin film deposition. APPJ has been produced, using a high voltage and high frequency power supply (0-20 kV) and an operating frequency of 20 kHz. Results showed that the electron density was of the order of 1014 cm-3 and 1016 cm-3 as determined by power balance, intensity ratio, and stark broadening methods respectively while electron temperature was estimated to be about 0.46 eV and 0.53 eV at 3 kV and 4 kV respectively by using intensity ratio method. The energy dissipation per cycle of the discharge was also estimated by using the Lissajous figure method. Our results confirmed that the parameter such as electron temperature and density depend on the applied voltage, gas flow rate, and electrode distance as well.

Investigation of the dependency of JET midplane separatrix density as a function of engineering parameters

AbstractMidplane separatrix density is a crucial parameter in tokamaks since it strongly impacts divertor conditions. Scaling midplane separatrix density, ne, SEP, and pedestal density, ne, PED, as function of engineering parameters such as auxiliary heating Pinjected, toroidal magnetic field BT, and plasma poloidal current Ip are relevant to observe the effect of tuning these parameters on, for example, quality of confinement and divertor regime governed by ne, PED and ne, SEP, respectively. Thus, a dataset of JET H‐mode pulses performed with Iter like wall (ILW) has been analysed. Midplane density data are collected from an HRTS (high‐resolution Thomson scattering) diagnostic and ne, SEP is determined using the power balance method. Parallel heat flux model is chosen using transport code SOLEDGE2D (S2D) applying power balance method over a simulated ne, SEP and Te, SEP profiles to obtain separatrix positions. The parameters are averaged over time windows with order of (85–185 ms) and the magnetic configuration has been fixed to avoid divertor geometrical effect on ne, SEP determination, configuration chosen is corner–corner. A ratio between separatrix density and pedestal density at outer midplane ranges between 0.3 and 0.7 on the data set. A scaling law of ne, SEP/ne, PED is obtained as function of Pinjected, BT, and IP.

Modified Modulation Strategy of 1: 1: 2 Asymmetric Nine-Level Inverter and Its Power Balance Method

The three unit nine-level inverter can output more voltage levels with fewer h-bridge units, while having better output waveform quality. However, in the conventional hybrid frequency modulation strategy, only one low-voltage unit adopts pulse width modulation (PWM), which causes the problem of switching loss and uneven heat distribution between the two low-voltage units. At the same time, the output power of the conventional modulation strategy is unbalanced. Aiming to resolve the above problems, a modified hybrid modulation strategy and a power balance control method under the strategy is proposed in this paper. The modulation strategy achieves output power balance between the three units and an even distribution of switching losses between the two low voltage units while maintaining the same output power quality. Simulation and experimental results verify the feasibility of the modulation strategy.

Design and Simulation of Current Sensor based Electronic Load Controller for Small Scale Three Phase Self Excited Induction Generator System

In standalone renewable energy systems, the power balance methods must exist to match the generated power and load demand; otherwise the excess power creates the disturbance in terms of voltage and frequency fluctuations. This paper presents a design and simulation of an electronic load controller (ELC) for the power balance in constant power prime mover-coupled three phase self-excited induction generator (SEIG) system. A current sensor based ELC is designed in such a way that to operate the generator unit always at its full capacity by coordinating between the two load systems termed as main and dump load. The controller unit has an uncontrolled 3-phase full-bridge rectifier circuit, a logically controlled insulted-gate bipolar transistor (IGBT) chopper switch, and a current sensor. The current sensor provides the feedback signal to the gate trigger circuit of IGBT and which inevitably controls the ON/OFF position of the switch. The ON condition of switch means a partial or full portion of generation power is diverted to the dump load, and the sum of both loads is equal to the rated capacity of SEIG. The proposed system is simulated in MATLAB, and the power balance is achieved with help of ELC. The voltage regulation of SEIG is addressed by adding extra reactive power (VAR) compensation. Further, in this study, the basic configuration of SEIG and the importance of self-excitation phenomena for voltage generation are also highlighted.

Electrical Characterization of an Atmospheric Pressure Plasma Jet

In this work, a plasma jet has been generated with capillary tube having external diameter 4.0 mm and thickness 1.0 mm. Argon has been used as a working gas. The electrical characteristics of this device like instantaneous power, and discharge current have been measured. The effects of applied voltage on the dissipated power of the device have been investigated. The current is measured with the current probe whereas the voltage is measured from the locally fabricated voltage divider having ratio 1201:1. The electron density has been found out using power balance method. In addition, the power consumption during the discharge has also been studied with the help of Lissajous Figures. The calculated power consumption has been compared with other manual as well as I-V plots.

Study of Dielectric Barrier Discharge in Air and Estimation of Electron Density and Energy Deposition

This paper reports the electrical behaviors of atmospheric pressure plasma reactor with Dielectric Barrier Discharge (DBD) in air medium. The DBD discharge was generated in air at atmospheric pressure using Disc Electrode Geometry (DEG) reactor powered by ac voltage (0-7kV) at a frequency of 24kHz. The glass plates of thickness 1.0mm and 3.0mm were used as dielectric. The current-voltage characteristics were studied for two air gap of 2.0mm and 3.0mm by varying the applied voltages. The numbers of filamentary micro discharges were found as increased in each half cycle with increase in power. The observations of Lissajous figure of applied voltage versus electric current was used for measuring energy deposited by discharge and also compared with calculated value. Lissajous figures clearly show that the energy deposited by discharge was dependent on applied voltage. The electron density of discharge was measured by power balance method. Electron density was found in the order of 1017 per cubic meter.