AC Applications Research Articles

The AC battery – A novel approach for integrating batteries into AC systems

The growing share of renewable energy technology is continuously transforming the energy sector. Using storage capacities becomes crucial to sustainably guarantee stable energy supply. In particular battery storage systems (BSS) are expected to successfully compete with alternative options for energy storage in the near future. Major issues with state-of-the-art BSS include comparatively high costs, limited efficiency as well as reliability, and a low fault tolerance. A leap in power electronics technology might meet these challenges, as the aforementioned characteristics are predominantly determined by existing power converter and BSS architectures.This paper presents the so-called AC Battery – a novel modular multilevel parallel converter based split battery system for AC applications, enabling dynamic switching of battery cells in parallel and in series. Each individual battery cell may be interconnected to its neighbors according to operational needs, e.g. to provide optimum source resistance, lowest state-of-charge (SOC) cycling, and balanced aging, rendering separate battery management systems (BMS) unnecessary. Applying the proposed technology in grid scale BSS may fundamentally change existing system architectures, as it merges battery storage system and power converter. This forms the basis for a highly integrated power electronics unit that includes bidirectional grid connection capability, energy storage, and BMS.

AC Loss Property of Stacked REBCO Superconducting Multifilamentary Tapes under Perpendicular Magnetic Field

For AC applications of high-temperature superconductors, such as REBa2Cu3Oy (REBCO, RE = rare earth) superconducting tapes, an AC loss is a great part of total heat load of cooling systems. In the case of conduction cooling, it may cause a serious temperature rise of the superconducting systems. Therefore, it is very important to reduce the AC loss in superconducting windings and grasp its properties under various conditions. For AC loss reduction, REBCO tapes should be scribed into a multifilamentary structure by the laser-scribing technique. In this study, AC loss properties in the non-scribed and scribed tapes were investigated, especially for Bm < Bp, where Bp is the breaking point of the AC loss curve and corresponds to the penetration field where the magnetic flux penetrates to the center of the tape or filaments. Further, the dependences of Bp on the number of stacking tapes and filaments were investigated from the viewpoint of demagnetization effect. It was cleared that the AC loss for Bm < Bp decrease and Bp increase with increasing number of stacked tapes.

A critical analysis of Z-source converters considering the effects of internal resistances

ABSTRACTNowadays Z-source networks are the most promising power converter networks that cover almost all electric power conversion (dc–dc, dc–ac, ac–dc and ac–ac) applications. However, the controller design is critical for Z-source converter (ZSC) due to the presence right-half-plane zero (RHPZ) in the control-to-capacitor-voltage transfer function. This RHPZ exhibits non-minimum phase undershoot in the capacitor voltage and also in the dc-link voltage waveforms. A perfect small-signal model is required to predict locations of the RHP zero and its dynamics. This paper contributes towards the small-signal analysis of ZSC under continuous conduction mode considering the parasitic resistance of the inductor, equivalent series resistance of the capacitor, internal resistances of active switch and forward voltage drop of the diode. The maximum allowable value of shoot-through duty ratio (STDR) and voltage gain for different values of the internal resistance and load resistance are discussed in this paper. The accuracy of the developed small-signal average model is compared with detailed circuit model in MATLAB/SIMULINK. Finally, the steady-state simulation results of ZSC are validated with hardware results.

Composite Superconducting MgB2 Wires Made by Continuous Process

Previously developed manufacturing technology of a low-cost composite single core based MgB 2 superconductive wires has been investigated in details using monel sheath and titanium diffusion barrier. In this process, Mg and B as well as nanoSiC dopant powders were fed continuously to a “U”-shaped metallic sheath titanium, and subsequently monel sheath. Resulting wires were assembled in a “6 + 1” configuration cable constructed from six 0.75-mm Monel/Titanium/(MgB 2 + 10 wt%SiC) and Monel/Titanium/MgB 2 wires and one central copper wire with two twist pitch arrangements: 13 mm. Undoped and SiC-doped wires were compared in respect of their I c (B, T ) characteristic. Wires were sintered at 700 °C for different times and subsequently were initially tested in a dedicated helium force vapor cooling system at temperatures 20-35 K at 1 T. Systematic and statistic I c (B, T ) measurements of the wires and cables in LHe were conducted at high external magnetic flux density up to 9 T. It was shown that wire feeding, sealing, reduction, and forming technology enable virtually unlimited conductor lengths as well as in-line processing control simultaneously ensuring a high degree of reproducibility and consistent quality of the MgB 2 superconductor. Such generic single core MgB 2 conductors enable manufacture of multifilamentary MgB 2 conductors with desired configurations (e.g., twist pitch for transient losses and ac applications).

Recent Status and Progress on HTS Cables for AC and DC Power Transmission in Korea

The direction of the development of large-scale electric power networks has very much coincided with the history of increasing voltage values ever since the advent of Joule heat loss. However, a high-temperature superconducting (HTS) technology has changed the direction of that history. Furthermore, the HTS technology will rapidly accelerate the speed of such change due to its extremely high current density with no Joule heat loss. For these reasons, many different types of HTS electric power transmission applications have been being discussed, and selected items have been developed. Within a few decades, the technology of HTS ac and dc power transmission applications had already been developed and close to the required level for industrialization. Moreover, some of these applications have been installed, energized, and are operating within real power networks. In this paper, we report on the current status and progress in HTS applications of ac and dc power transmission. In particular, this paper focuses on the application field of superconducting cable among various HTS power applications. In South Korea, the Korea Electric Power Corporation, Naju, aims to introduce more new technologies in order to develop the Korean power network, and it believes that an HTS is a key factor in the development of the next generation of power grid, which will be discussed in detail in this paper.

A Highly Efficient Fully Integrated GaN Power Amplifier for 5-GHz WLAN 802.11ac Application

In this letter, a novel compact on-chip output matching network to achieve harmonic impedance matching is proposed. With the proposed matching network, a highly efficient GaN monolithic microwave circuit power amplifier (PA) is designed for 5-GHz wireless local area network 802.11ac application. The implemented PA achieves a maximum power-added efficiency (PAE) of 49.5%–61.3% over the frequency band from 4.9 to 5.9 GHz, with a saturated output power (Psat) of 34.6–36.1 dBm. When tested with 802.11ac VHT80 MCS9 (80 MHz, 256-quadratic -amplitude modulation) signal with 11.3-dB peak-to-average power ratio, the PA achieves an average output power of 23.7–26.3 dBm, with a PAE of 24.9%–30.9%, while meeting the standard error vector magnitude specification of −32 dB.

DEVELOPMENT OF AN EGG INCUBATOR USING LIGHTING CIRCUIT WITH SWITCHING POWER SUPPLY

Chicken eggs are often incubated in complete darkness, obtaining light only fitfully with the incubator opening during the incubation process. There is very little knowledge available as to how light system effect on bird’s production, and no data available as which light type is more energy-efficient in using. Therefore, this paper offers the modification of the design for egg incubator that will be used easily, affordable and simple to maintain and concentrates on aims to give a comprehensive concept of environmental stimuli during incubation can affect the chicken production. Thus, this paper aimed at designing and evaluating the performance of a LED lighting circuit that is applied in an egg incubator, for the ability to increase the hatching rate with the lowest power consumption using a switching power supply.The present study suggests using mosfet, capacitor, and inductor for AC applications, in this circuit that is rectified the output current through a bridge rectifier as well as reduces its ripple. This current is uniform with DC applications which suits to drive LED lighting system. This is a low cost and dynamic circuit and can be used for lamps up their power 40W effectively. To evaluate the effect supplying of the lighting system during the incubation period, it was incubated chicken eggs by an amplitude of 720 eggs under variable luminous flux and different lighting periods compared with incubation in the dark. It was demonstrated that providing LED light during incubation can reduce daily power consumption compared with the other lighting systems as well reduction of the death rate of embryos post-hatch. The results obtained of the test revealed the highest hatchability proportion value was 86.88% with daily power consumption of 154.32 W under luminous flux of 700 lm within 12 h of the lighting period as compared to 77.83% which was incubated in complete darkness, The equation of the trend line related to highest hatchability percentage is The Energy Consumption =78.852 luminous power + 8.58.

Synchronized measurement technology supported AC and HVDC online disturbance detection

In electric power system, disturbance detection has become an important part of grid operation and refers to the detection of a voltage and current excursion caused by the wide variety of electromagnetic phenomena. This paper proposes a computationally efficient and robust algorithm for synchronized measurement technology (SMT) supported online disturbance detection, suitable for AC and HVDC grids. The proposed algorithm is based on the robust median absolute deviation sample dispersion measure to locate dataset outliers. The algorithm is capable of identifying the disturbance occurrence and clearance measurement sample based on the dynamic criteria, driven by present power system conditions. The effectiveness of the proposed algorithm is verified by real-time simulations using a cyber-physical simulation platform, as a co-simulation between the SMT supported electric power system model and underlying ICT infrastructure. The presented results demonstrate effectiveness of the proposed algorithm, making it suitable for an AC and HVDC online disturbance detection application or as a pre-step of backup protection schemes.

SCC Initiation for X80 Pipeline Steel Under AC Application in High pH Solution

SCC Initiation for X80 Pipeline Steel Under AC Application in High pH Solution

SCC Initiation for X80 Pipeline Steel Under AC Application in High pH Solution

SCC Initiation for X80 Pipeline Steel Under AC Application in High pH Solution

Comparison of AC Losses of YBCO Circular Pancake Coils and Infinitely Long Stack Approximation

High-temperature superconducting (HTS) coils are key parts of many large-scale AC applications, such as transformers, superconducting magnetic energy storage, and motors. The estimation of AC losses of pancake coils is necessary for optimizing the design of HTS devices and cryogenic systems. To speed up the computation of AC losses, the numerical model of an infinitely long HTS stack is often utilized. An HTS stack is a good approximation of the circular coil only if the coil radius is sufficiently large, since AC losses will exhibit a stronger asymmetry along the radial direction for small values of coil radii. To assess the validation of an infinitely long stack approximation, the comparisons of AC losses between infinitely long stacks and circular coils with different radii are presented. The turn number varies from 10 to 80. We find that the AC losses of HTS circular coils will gradually increase to the same value as an infinitely long stack with increasing coil radii. A new parameter is proposed to quantitatively describe the correctness of infinitely long stack approximation. Finally, a method of AC loss estimation of HTS pancake coils is proposed.

Tracking and erosion resistance of LSR and HTV silicon rubber samples under acid rain conditions

Assessment of the material degradation in laboratory similar to field conditions is still a challenge. In the present work an attempt is made to study the effect of environment conditions in service life of polymeric insulators on tracking and erosion resistance. Evaluation of tracking and erosion resistance of Silicone Rubber insulating samples of high temperature vulcanized (HTV) rubber and liquid silicone rubber (LSR) are carried out under AC and positive polarity DC voltage. The samples are treated under normal contaminants as per IEC 60587 and acidic contaminant solution simulating acid rain. The conditions of pollution/ contamination severity level are taken into consideration by maintaining the conductivity approximately 2.5 mS/cm for both solution to observe the effect of acidity alone on the samples, the acidity level is varied to understand the material behavior under acidic case with AC and DC stress application. A new experimental arrangement is set up based on IEC 60587 and ASTM D-2303 standards. The constant voltage method is employed to find the relative tracking performance of silicone rubber samples for different chemical composition. Physico-chemical analysis involving SEM, EDAX and FTIR is carried out on treated samples to understand the surface morphology and chemical changes. A comparative analysis is carried out for the acid rain solution and the standard solution of NH 4 Cl. Further leakage current performance and analysis is carried under both AC and DC stress.

Hasil Belajar dan Aktivitas Siswa Setelah Diterapkan Pembelajaran Guided Inquiry Pada Materi Penerapan Listrik DC dan AC

&#x0D; This study aims to determine the results of student learning after applied physics learning using guided inquiry model and student activities during the process of physics-based learning guided inquiry in high school on the material Application of AC and DC Power. Implementation of this learning using one group pretest-posttest design, the first step to make measurements as the initial test, then subject to treatment within a certain time, then performed the final test. After doing teaching and learning activities on the material application of DC electricity and AC classical completeness reached 91.7%. The average student learning outcomes after guided inquiry based learning activities increased from 34.2 to 85. The most frequent student activity in the guided inquiry learning phase was experimentation and listening to teacher's explanation of 14%.&#x0D;

Numerical study on AC loss reduction of stacked HTS tapes by optimal design of flux diverter

High temperature superconducting (HTS) coils are key parts of many AC applications, such as generators, superconducting magnetic energy storage and transformers. AC loss reduction in HTS coils is essential for the commercialization of these HTS devices. Magnetic material is generally used as the flux diverter in an effort to reduce the AC loss in HTS coils. To achieve the greatest reduction in the AC loss of the coils, the flux diverter should be made of a material with low loss and high saturated magnetic density, and the optimization of the geometric size and location of the flux diverter is required. In this paper, we chose Ni-alloy as the flux diverter, which can be processed into a specific shape and size. The influence of the shape and location of the flux diverter on the AC loss characteristics of stacked (RE)BCO tapes is investigated by use of a finite element method. Taking both the AC loss of the (RE)BCO coils and the ferromagnetic loss of the flux diverter into account, the optimal geometry of the flux diverter is obtained. It is found that when the applied current is at half the value of the critical current, the total loss of the HTS stack with the optimal flux diverter is only 18% of the original loss of the HTS stack without the flux diverter. Besides, the effect of the flux diverter on the critical current of the (RE)BCO stack is investigated.

Frequency Dependence of Low-Voltage Electrowetting Investigated by Impedance Spectroscopy.

An electrowetting-on-dielectric (EWOD) electrode was developed that facilitates the use of low alternating voltages (≤5 VAC). This allows online investigation of the frequency dependence of electrowetting by means of impedance spectroscopy. The EWOD electrode is based on a dielectric bilayer consisting of an anodic tantalum pentoxide (Ta2O5) thin film (d = 59.35 nm) with a high relative permittivity (εd = 26.3) and a self-assembled hydrophobic silane monolayer. The frequency dependence of electrowetting was studied using an aqueous μL-sized sessile droplet on the planar EWOD electrode in oil. Experiments using electrochemical impedance spectroscopy and optical imaging indicate the frequency dependence of all three variables in the Young-Lippmann equation: the voltage drop across the dielectric layers, capacitance per unit area, and contact angle under voltage. The electrowetting behavior induced by AC voltages is shown to be well described by the Young-Lippmann equation for AC applications below a frequency threshold. Moreover, the dielectric layers act as a capacitor and the stored electrostatic potential energy is revealed to only partially contribute to the electrowetting.

Magnetic Properties of Metal - Polymer Composites for Ac Applications at High Frequencies

This paper presents the soft magnetic properties of the Fe-, Ni-, Co- and Fe-Co-Ni polymer composites. The composites were ob-tained with Fe, Ni and Co powders (99.9% purity) with particle sizes of 150, 10 and 2 mm, respectively. Ring-shaped samples were ob-tained using uniaxial compaction at 91 MPa. The Fe-Co-Ni-polymer composite has the highest value of the magnetic permeability (μ=54) at 107 Hz and saturation magnetization (Ms=10000 Am2Kg-1) higher than the Ni-polymer composite (4100 Am2Kg-1).

WITHDRAWN: OPTIMIZATION OF CAPILLARY TUBE DIMENSIONS USING DIFFERENT REFRIGERANTS FOR 1.5 TON MOBILE AIR CONDITIONER

Abstract Capillary tube is one of the commonly used throttling devices in the refrigeration and the air conditioning systems. The capillary tube is made up of copper tube of very small internal diameter. It is of very long length and it is coiled to several turns so that it occupies less space. The internal diameter of the capillary tube used for the refrigeration and AC applications varies from 0.5 to 2.28 mm (0.020–0.09 inches). Capillary tube used as the throttling device in the refrigerators, deep freezers, water coolers and air conditioners. The objective of this research was to evaluate the optimum size of a capillary tube dimensions in a Air Conditioning system and to determine the Pressure drop across the capillary tube. The optimization was determined by mathematical calculation to evaluate increment length.

A Compact Hybrid Multiband Antenna for Wireless Applications

This paper presents design of Compact Hybrid Multiband Antenna (CHMA) for various wireless applications. The projected antenna geometry is designed by integrating moore and gosper curves and their characteristics are investigated. The antenna reveals multiband behavior along with satisfactory values of all performance parameters in spite of less complexity and compact size. The small cost simulated antenna is designed on FR4 substrate, which shows gain of 16.65 dB along with return loss of −18.39 dB and VSWR of 1.27 at 2.4 GHz frequency. Simulated results exhibits six operational bands that cover various significant frequency bands like Air traffic control RADAR (0.96–1.215 GHz), GSM (1.85–1.99 GHz), Wi-Fi (2.4 GHz for 802.11b, 802.11n and 802.11g), WLAN 802.11a/b (5.15–5.35 GHz), WLAN 802.11ac (5.5 GHz) and military satellite applications (7.9–8.4 GHz). The simulation results of antenna in terms of antenna parameters like Return Loss (RL), radiation pattern, Voltage Standing Wave Ratio (VSWR) and Gain (G) are evaluated using HFSS (High Frequency Structural Simulator); v13 software. The hybrid antenna is designed with line feed having compact size of 55 mm (L) × 60 mm (W) × 1.6 mm (H) on FR4_epoxy substrate with er 4.4. Both simulated and measured results are analyzed, compared and presented in the paper. Proposed antenna operates from 0.98 to 8.1 GHz and covers L, S, C and X band applications.

Spark-Discharge Plasma as a Method to Produce Low AC Loss Multifilamentary (RE)Ba2Cu3 O7 Coated Conductors

If coated conductors are to be used in large-scale ac applications such as motors and generators, energy losses must be minimised. Hysteretic ac losses can be reduced by dividing the coated conductor into filaments. In this study, a new method for producing filamentary coated conductors is presented. An electrical spark discharge was used to selectively degrade regions of superconducting tape. The robust, noncontact and scalable method was used to striate tapes into four filaments. The filamentary samples had lower ac losses than nonstriated tapes with less than a 7% reduction in current carrying capacity.

Decomposition of benzene using wire-tube AC/DC discharge reactors

Decomposition of benzene was investigated using single and two-stage stainless steel reactors with application of high-voltage AC and DC currents. Benzene removal, CO, and CO2 were measured as a function of reactor diameter, applied voltage, and stage of reactor configuration. The results showed that, benzene removal and CO2 selectivity improved in two-stage configuration and reached up to 59% and 97.8% respectively, where the gap size was 8.5 mm. Formation of OH, N-H and N=O function groups were seen in the exhaust gas. Subsequently, organic acids, phenols, and alcohols were identified as the main byproduct of benzene decomposition considering GC-MS analysis.