Line Circuit Research Articles

Electromagnetic coupling evaluation of small metal enclosures with apertures using analytical, numerical and measurement analysis

We have presented an analytical analysis of the shielding effectiveness of small metal enclosures with apertures by the Roinson model based on the theory of transmission line circuits, as well as a numerical analysis by the finite-difference time-domain method (FDTD) and finite integgration technique (FIT) under the CST Software software, the results returned by these methods were compared with those provided by the measurement, the comparative study reveals a good agreement between the simulation and the measurement. The study carried out in this article has resulted in very significant results allowing to solve electromagnetic compatibilty (EMC) type problems related to the reduction of the electromagnetic field in an enclosure with apertrures.

Low-dielectric thermosetting resins derived from polysaccharide unsaturated esters

Printed circuit boards (PCBs) contain metals and plastics, with the latter often incinerated after disposal, leading to carbon dioxide emissions. This study focuses on developing biomass-based thermosetting resins derived from polysaccharides. Cellulose and α-1,3-glucan were introduced with unsaturated (2-butenoate) and saturated (hexanoate) ester groups to achieve appropriate properties for PCB applications. The synthesized polysaccharide esters, cellulose-2-butenoate-hexanoate and α-1,3-glucan-2-butenoate-hexanoate, demonstrated thermoformability at 150 °C, suitable for being laminated on circuit lines. After heating at 220 °C for 1 hour, the unsaturated parts of the polymers crosslinked, increasing the glass transition temperature to over 230 °C, making them potentially durable for the soldering process. The dielectric constant and dissipation factor of the crosslinked resins ranged from 2.5 to 2.7 and 0.012 to 0.014, respectively, outperforming conventional epoxy resins to reduce transmission loss. Additionally, the crosslinked films exhibited robust mechanical properties with tensile strengths exceeding 50 MPa. These results indicate that polysaccharide unsaturated esters are promising for use as PCB insulating resins, providing a sustainable alternative to petroleum-based materials.

A microwave sensing system combination of interdigital structure (IDS)-based microstrip line and RF circuits for extracting complex permittivity of liquid samples

In this manuscript, a microwave sensing system for extracting complex permittivity of binary aqueous solutions based on a modified microstrip line with interdigital structure (IDS) etched is proposed. The passive resonance unit and active circuits constitute the microwave sensing system. The passive resonance unit is evolved from conventional microstrip line with the characteristic impedance of 50Ω, then the IDS is etched on the top surface of passive resonance unit to enhance the confinement of electrical field. The modified passive sensor can produce two resonant modes, i.e., odd-mode 1 and odd-mode 2, the electrical fields of these two modes are both concentrating at IDS, and odd-mode 1 with higher density of electrical field is adopted to retrieve complex permittivity of liquid samples. Except for the passive sensor, the sensing system consists of power divider, low noise amplifier (LNA), isolator, orthogonal hybrid coupler, phase shifter, mixer, and low-pass filter (LPF). The proposed microwave sensing system has two output DC voltages, i.e., channel-I and channel-Q. The mathematical relationship between complex permittivity and resonant frequency shift can be transformed into the relation between complex permittivity and two DC voltages by the proposed microwave sensing system, which is beneficial to discard the use of VNA. The two output voltages of microwave sensing system will be changed according to the injections of liquid samples with different complex permittivity, then the mathematical models can be established by summarizing the rule between complex permittivity and DC voltages. Finally, the established mathematical models can be adopted to predict the binary aqueous solutions with unknown complex permittivity. In measurement, the proposed microwave sensing system has the average sensitivities of about 2.478 mV/εr′ and 1.418 mV/εr′ for channel-I and channel-Q, respectively, which are several times higher than other reported ones. Low-cost, high sensitivity, convenient measurement, and easy fabrication are the merits for the proposed sensing system, and it is a good template in the region of detecting liquid samples.

Soliton solutions of the TWPA-SNAIL transmission line circuit equation under continuum approximation via the Jacobi elliptic function expansion method

Soliton solutions of the TWPA-SNAIL transmission line circuit equation under continuum approximation via the Jacobi elliptic function expansion method

A hybrid intelligent system for protection of transmission lines connected to PV farms based on linear trends

Conventional relays face challenges for transmission lines connected to inverter-based resources (IBRs). In this article, a single-ended intelligent protection of the transmission line in the zone between the grid and the PV farm is suggested. The method employs a fuzzy logic and random forest (RF)-based hybrid system to detect faults based on combined linear trend attributes of the 3-phase currents. The fault location is determined and the faulty phase is detected. RF feature selection is used to obtain the optimal linear trend feature. The performance of the methodology is examined for abnormal events such as faults, capacitor and load-switching operations simulated in PSCAD/EMTDC on IEEE 9-bus system obtained by varying various fault and switching parameters. Additionally, when validating the suggested strategy, consideration is given to the effects of conditions such as the presence of double circuit lines, PV capacity, sampling rate, data window length, noise, high impedance faults, CT saturation, compensation devices, evolving and cross-country faults, and far-end and near-end faults. The findings indicate that the suggested strategy can be used to deal with a variety of system configurations and situations while still safeguarding such complex power transmission networks.

Analysis of hybrid AC/DC transmission system: A Turkey case study

AbstractThe need to transmit energy in the most effective way arises in parallel with the demand for energy in developing countries. As the amount of transmitted power increases, transmission lines can become overloaded, causing a blackout. This study aims to increase the transmission capacity without experiencing right‐of‐way problems by converting Turkey's existing high voltage AC systems to hybrid AC/DC systems. With such a design, it is aimed at providing more efficient and continuous transmission by using the high‐voltage DC system's low‐loss feature at long distances. Using the 400 kV double circuit line structure, the existing electricity transmission system is modelled using real data in the DigSILENT PowerFactory. The electromagnetic fields that will occur due to the use of AC and DC circuits on the same tower in such a transformation situation are analysed with FEMM 4.2, based on the finite element method. The compliance of the electromagnetic fields that will occur with the use of hybrid 400 kV AC and 500 kV DC was determined in the study. In addition, according to the simulation results, it is predicted that in the case of hybrid AC/DC transmission, the current transmission capacity would increase and the losses would decrease.

Physics-Based Impedance Model for Understanding Proton Transport in PEM Fuel Cells

The electrochemical impedance spectroscopy (EIS) diagnostics using H2/N2 operation condition developed for fuel cell is useful tools to estimate the catalyst layer (CL) proton resistance. Currently, the resistance is estimated by fitting the measured EIS data to an equivalent circuit model. However, it is challenging to correctly determine the transmission line circuit and accurately estimate the proton resistance [1]. Moreover, the capacitive and resistance elements in the transmission line model are assumed similar throughout the CL even if there is nonhomogeneous distribution of ionomer. To understand the EIS response in CL, we present a physics-based model. Utilizing the model, we are able to investigate the H2/N2 cell impedance response under various operating conditions. The continuum scale model will be combined with agglomerate scale model to provide a detail study of the electrode parameters like ionomer loading and ionomer coverage The hybrid theoretical model allows us to study the effect of nonhomogeneous CL and its corresponding EIS response. Acknowledgement This research is supported by U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office, through the Million Mile Fuel Cell Truck Consortium (M2FCT).

Mutual inductance parameter measurement and experimental research of double circuit based on different frequency method

AbstractIn order to improve the measurement accuracy of mutual inductance parameters of transmission lines in the environment of double circuit power lines without power outage, this paper establishes simulation models for measuring mutual inductance parameters of transmission lines using the different frequency method in two modes: equal and unequal zero sequence self‐parameters of two circuit lines, using a parallel zero sequence coupling model of double circuit power lines. In the article, simulation analysis is conducted on the line parameters with a coupling coefficient between 0.4 and 0.6 and a line length of 20–50 km. In order to further verify the correctness of the simulation model and measurement methods, a test bench was established based on the principle of line mutual inductance parameter testing in a laboratory dual circuit line without a power outage environment for experimental testing. By comparing the test values under experimental conditions with the standard values, it has been proven that the model and method can meet the actual measurement requirements of engineering.

A new method for synthesis and designing transmissive linear-to-circular polarization converters based on branch line circuit model

This paper proposes a new design method of a linear-to-circular polarization converter based on the branch line circuit model. The series branches are implemented by dielectric spacers and the shunt branches are implemented by anisotropic admittance sheets. The admittance matrix of the anisotropic admittance sheets is derived by even and odd mode analysis. A unit cell consisting of two metal layers and a dielectric spacer is then designed using an iterative algorithm for operation from 15.5 to 23 GHz. Results indicate that the axial ratio and insertion loss of the designed polarizer are better than 3 and 1.5 dB respectively, for incident angles between ±45°. To validate the simulation results, a waveguide-based test setup is designed and fabricated, with measurement results indicating good agreement with simulations. The proposed method can be potentially applied to design other anisotropic structures such as half-plate polarizers and polarization rotators.

Underground Cable Fault Detection Using IOT

Abstract: The objective of this project is to determine the distance of underground cable fault from base station in kilo meters using an Arduino. The underground cable system is a common practice followed in many urban areas. An issue may happen in an underground cable just because of earth tremors or any burrowing procedure. Since the area of the issue happened is obscure it is very hard for the fixing procedure. This hindrance is handled with the assistance of optical fibre framework. A lot of optical strands is put alongside the force cables. While a fault occurs for some reason, at that time the repairing process related to that particular cable is difficult due to not knowing the exact location of the cable fault. The proposed system is to find the exact location of the fault. The project uses the standard concept of Ohms law i.e., when a low DC voltage is applied at the feeder end through a series resistor (Cable lines), then current would vary depending upon the location of fault in the cable. In case there is a short circuit (Line to Ground), the voltage across series resistors changes accordingly, which is then fed to inbuilt ADC of Arduino to develop precise digital data for display in kilometres. The project is assembled with a set of resistors representing the cable length in km and the fault creation is made by a set of switches at every known km to cross check the accuracy of the same. The fault occurring at a particular distance, the respective phase along with the distance is displayed on the LCD. The same information is also sent over IOT, interfaced to the Arduino. Further this project can be enhanced by using capacitor in an ac circuit to measure the impedance which can even locate the open circuited cable, unlike the short circuited fault only using resistors in DC circuit as followed in the above proposed project.

An online detection method for the mechanical fault of circuit breakers of rural distribution lines based on continuous wavelet transform and vibration signal characteristics

Rural distribution lines are widely distributed and dispersed, involving numerous circuit breaker equipment. Detecting mechanical faults on each circuit breaker requires significant time and human resources. It can bring significant interference and power outage risks to the operation of the line. Therefore, an online detection method is studied for mechanical faults in rural distribution line circuit breakers. Continuous wavelet transform technology is used to extract the characteristics of circuit breaker vibration signals. This feature is used to locate the faulty section. The PNN neural network is introduced to identify fault feature samples and achieve online detection of mechanical faults. To test the application performance of this method, a comparative experiment is designed. The results verified that when using this method to extract the vibration signal of circuit breaker mechanical faults, the error is low, and the fault detection accuracy is high.

Pressure safety approach for PIP-II cryogenic distribution system and cryomodules

The Proton Improvement Plan-II (PIP-II) is a superconducting linear accelerator being built at Fermilab that will provide 800 MeV proton beam for neutrino production. The linac consists of a total of twenty-three (23) cryomodules of five (5) different types. Cooling is required at 2K, 5K and 40K. The Cryogenic Distribution System (CDS) consists of a Distribution Valve Box, ~285 m of cryogenic transfer line, modular Bayonet Cans to interface with cryomodules, and a Turnaround Can. The cryogenic system must provide protection from over-pressure by sizing pressure relief devices for all volumes and process line circuits. The cryomodule cavity circuits have dual pressure ratings, 4.1 bara when cold and 2.05 bara when warm (T>80K). Worst case relieving cases will be identified. The methods for determining heat flux will be presented. For the relieving occurring in the linac tunnel, flow must vent to outside to avoid an oxygen deficiency hazard. Also, we will present vacuum vessel relief sizing to protect the cryogenic distribution system vacuum shells from over pressure during an internal line rupture. The project is funded by US DOE Offices of Science, High Energy Physics.

The Indirect Effect of Lightning Electromagnetic Pulses on Electrostatic, Electromagnetic Fields and Induced Voltages in Overhead Energy Transmission Lines

The impact of a lightning electromagnetic pulse (LEMP) on a power line or power station produces an effect similar to that of switching between a significant power source and a power line circuit. This switch closure causes a sudden change in routing conditions, creating a transient state. This situation has been studied in terms of electrostatic and electromagnetic induction, as well as overvoltage changes. Appropriate mathematical models were used to analyze these changes. While vertical electric field analysis has been carried out in a few studies, magnetic field and horizontal electric field vectors have not been studied. In this study, the Rusck formulation and the Heidler current formulation are combined at the current level, developed and analyzed. This is because the Rusck expression can sometimes give incorrect results at the current level. Also, in the analysis, electromagnetic field formulations based on accelerating charges are used instead of the dipole approximation to eliminate the need for interpolation in the graphical results. In contrast to other studies in the literature, this study proposes the use of moving and accelerating load techniques to better understand the effects of LEMPs on power transmission lines. Also, in this study, the double exponential problem of the current form in Rusck’s formulation is addressed in order to obtain a close approximation of the physical form of the LEMP. Additionally, the field–line (coupling) relationship is studied according to a unique closed formulation, leading to important determinations about the overvoltages generated on a line depending on the propagation speed of the LEMP sprout and the electrical changes in the area where the LEMP first occurs.

On Increasing the Reliability of Line Circuit Breakers when Disconnecting Overhead Power Lines in Conditions of Slightly Negative Ambient Temperatures

On Increasing the Reliability of Line Circuit Breakers when Disconnecting Overhead Power Lines in Conditions of Slightly Negative Ambient Temperatures

Laser-Induced Selective Metallization on Aluminum Nitride for Fine Line Circuits

The technology of laser direct selective metallization on aluminum nitride substrate was investigated for manufacturing fine line circuits. In laser direct structuring, laser activation and electroless copper plating were used. The feasibility was evaluated by analyzing the sieving, contrast, and fine linewidth patterns, and the results showed that the width of the feasible fine reached 100 μm. A near-field communication (NFC) antenna circuit of the width of 400 μm was fabricated on the aluminum nitride substrate. The measured resonance frequency was close to the NFC specification frequency.

A novel approach to retrograde autologous priming for infant, pediatric and adult populations undergoing congenital heart surgery.

Retrograde Autologous Priming (RAP) of cardiopulmonary bypass (CPB) circuits is an effective way to reduce prime volume, commonly through the transfer of prime into separate reservoirs or circuit manipulation. We describe a simple and safe technique for RAP without the need for any circuit modifications or manipulations. For this technique, a separate roller pump for ultrafiltration (UF) is used. After adequate heparinization and arterial cannulation, the UF pump is initiated slowly, removing prime through the effluent of the UF, replacing with the patient's blood from the aortic cannula. Once the arterial line and UF circuit are autologous primed, the arterial head displaces reservoir crystalloid toward the UF circuit at a flow rate equal to the UF pump, displacing the crystalloid prime with blood from the UF circuit, autologous priming the boot and oxygenator with blood, crystalloid again being removed by the effluent. After venous cannulation, the venous line prime is replaced with autologous blood, the crystalloid removed by the effluent of the UF circuit via the arterial head. During RAP, if the patient becomes hypovolemic, either autologous volume is transfused back to the patient, or CPB is initiated, without the need for circuitry modifications. The patient population in this sample consisted of 63 patients ranging between 6.1kg and 115.6kg. The smaller the patient, the less blood volume available for RAP and therefore the less prime volume able to be removed. Overall percent removal increases as our patients size increases compared to total circuit volume. This RAP technique is a safe and effective way to achieve a standardized asanguinous prime for many regardless of patient or circuit size in the absence of contraindications such as low starting hematocrit, emergency surgery or physiologic instability. Most importantly, this potentially reduces the amount of hemodilution patients see from CPB initiation and therefore the lowest nadir hematocrit and consequently the amount of required homologous blood products needed during surgery.

A novel design methodology for asymmetric coupled line passive devices and its application in impedance transformers

ABSTRACT This article presents a novel design methodology for asymmetric coupled line passive devices. Based on the extraction of distributed parameters of coupled lines from S-parameters, we re-derived modal characteristic parameters and Z matrix of four-port asymmetric coupled lines in inhomogeneous mediums. Then, Z matrices of ten two-port asymmetric coupled line circuits are derived and their frequency responses are analyzed. Inspired by the image parameter method, image impedances are adopted for two-port device designs. Data diagrams which connect geometric parameters with impedances are provided to simplify design processes. Two impedance transformers utilizing the open-ended and short-ended coupled line circuits, respectively, producing high transforming ratios of 100 (50 Ω to 0.5 Ω) and 40 (50 Ω to 2000 Ω) are fabricated to verify the proposed analysis and design method. Excellent agreement between the simulation and measurement result proves the unique superiorities of asymmetric coupled lines with better initial values.

Assessment of photovoltaic generation penetration effect on the maximum loadability of the system

This paper proposed a method to investigate the effect of increasing PV penetration on the voltage stability of an IEEE 14-bus test system considering maximum PV penetration and system loadability limit. The critical bus of the test system has been decided based on nose curve analysis. The solar PV system is deployed with the most critical bus of the system. The effect of increasing PV penetration on the improvement in the loading capacity of various power system components like transmission lines, transmission line transformers, and generators is investigated over the adopted test system. Based on solar PV penetration up to 100 MW, the maximum loadability limit of the IEEE 14-bus test system increases, as shown by the results. Bus 14 is found to be the most severe bus of the test system using the continuation power flow (CPF) method. However, in some cases, overloading situations develop after a certain limit of PV penetration in the power system. In this condition, the overloading of the power system equipment is improved by the use of a Static Synchronous Compensator (STATCOM) at bus number 14, a double circuit line in the critical line (9–14), and Static Synchronous Series Compensator (SSSC) in the most severe line (9–14) in the system. The maximum loadability of the system gets maximum enhanced from 4.0349 p.u. to 4.5602 p.u. under simultaneous use of solar PV generation, SSSC, and STATCOM at the most critical bus and in most severe line of the system. As evidence, the enhancement in maximum loadability of the system found using the proposed method has been also compared with the existing research. The maximum system loadability has been also enhanced under normal and (N-1) contingency conditions by the use of PV penetration in the system. PSAT/MATLAB software is used for simulation and maximum loadability has been investigated by continuation power flow (CPF) method.

A graphene-based THz selective absorber with absorptivity 95 % and wide-range electrical tunability

A growing adoption of Terahertz (THz) frequency across various applications is witnessed in the recent years. This specific frequency range is said to yield a breakthrough in high-speed electronics and communications, besides its significant role in the medical field regarding scanning and treatment. As frequency absorbers are one of the common blocks in the mentioned applications, they were the focus of many research work. In this paper, we present a theoretical model for a selective THz frequency absorber that has more than 90 % absorptivity and can reach 95 % and near unity absorptivity at some frequencies. The structure is based on monolayers of nanoribbons of graphene, MoS2, and phosphorene. The utilization of the surface plasmon oscillations of these two-dimensional (2D) materials, in addition to the impedance matching, is employed to achieve maximum absorptivity. The structure has an electrically tunable selective frequency from 1.3 THz to 10 THz that nearly covers the whole THz range, and a bandwidth ranging from 0.9 THz to 1.3 THz. Electrical tunability is done through varying the applied voltage on the MoS2/graphene heterostructure (0.2 V ∼ 5 V) based on the tunable conductivity of graphene. In addition to the voltage tunability of the design, the absorption frequency is also swept by varying the nanoribbons widths (20 nm ∼ 160 nm). The proposed design surpasses previous ones by its simple structure and high absorption through the entire THz range, besides its low cost of fabrication. The structure is ultrathin (∼10 nm) that it can fit in ultrathin electronics. It has a relatively small bandwidth compared to previous work, that represents the basis for narrowband absorbers. The structure is simulated using the finite element method (FEM) and verified using the transmission line circuit theory which demonstrated the validity of the structure for higher frequency ranges. The possibility of future synthesis is also discussed.

Anomalies in the magnetostrictive modulation of love surface acoustic waves

A magnetic surface acoustic wave (SAW) sensor is built by growing a 100 nm galfenol (Fe72Ga28) film by sputtering between the interdigitated transducers of a SAW delay line. Love waves are produced when the shear waves excited on the piezoelectric substrate are guided by a 3.1 μm layer of amorphous SiO2. Due to the magnetostrictive nature of galfenol deposited on top, the application of magnetic fields modulates the propagation of the mechanical excitations along the sensor by the strain coupling. By introducing the delay line in a feedback loop circuit, these changes are studied as resonant frequency variations. Magnetic field cycles of ±40 mT are applied to the sample and the resonant frequency shift is tracked simultaneously. The sensor exhibited hysteretic frequency behavior that depends on the orientation of the applied magnetic field relative to the direction of Love wave propagation. In the configuration in which the wave vector and the applied field form an angle of 45°, the resonant frequency seems to increase with the magnetization induced by the external field. When the wave vector propagation is parallel to the field, two positive peaks appear close to the coercive field of the film, which has not been reported before. This is probably due to a more complex relationship between the acoustic wave and the magnetic state of the film which could be exploited to give rise to new models of magnetic sensors.