Combined Transmission Line Research Articles

A Facile Route Preparation of Fe3O4/MWCNT/ZnO/PANI Nanocomposite and its Characterization for Enhanced Microwave Absorption Properties

AbstractWith increasing concerns regarding the potential health risks associated with microwave‐based technology, researchers have been actively investigating materials with impressive microwave absorption properties. In this study, a synthesis and investigation of a nanocomposite, named Fe3O4/MWCNT/ZnO/PANI, consisting of magnetite (Fe3O4), multi‐walled carbon nanotube (MWCNT), zinc oxide (ZnO), and polyaniline (PANI) as a microwave‐absorbing material, was carried out for the first time. The nanocomposite was prepared through a simple physical mixing approach and demonstrated tunable microwave absorption, making it highly suitable for shielding applications. Structural analysis techniques, including X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy‐dispersive X‐ray analysis (SEM‐EDAX), confirmed the presence of all components in the nanocomposite. Moreover, ultraviolet‐visible spectroscopy (UV‐Vis) further verified the formation of nanocomposite components and revealed an adjustable optical bandgap ranging from 2.86 to 3.34 eV. Impressively, the nanocomposite exhibited promising microwave absorption properties, with a minimum reflection loss (RL) of −32.66 dB for the nanocomposite containing 37.50 % PANI by weight, and a maximum electromagnetic bandwidth (EB) of 2.26 GHz for the nanocomposite containing 44.44 % PANI by weight, indicating its potential as an effective shielding material. Furthermore, a modified theory combining transmission line, Landau‐Lifshits, and Drude‐Lorentz theories was introduced to extract complex relative permittivity and permeability, providing insights into the role of polyaniline in enhancing the microwave absorption properties of the nanocomposite as measured by reflection loss (RL).

A Fault Location Algorithm for Multi-Section Combined Transmission Lines Considering Unsynchronized Sampling

This paper introduces a fault location technique for multi-section combined transmission lines, utilizing unsynchronized fault record data. The approach determines the intersection points of the voltage magnitudes computed using the fault current and voltage records of each terminal and the constant line parameters of each section. Finally, the real fault location is identified based on the calculated inverse angle of equivalent impedance. To evaluate the performance of the proposed algorithm, a three-section combined transmission line is constructed using the PSCAD/EMTDC software version 5.0.0, and various fault scenarios are simulated and tested employing the proposed algorithm. The results indicate that the proposed algorithm is applicable to various types of faults in a multi-section combined transmission line; the estimations are accurate.

A Hybrid EMC Testing Facility: Combining Transmission Line and Reverberation Chamber Measurement System

By combining a transmission line system (TLS) and a reverberation chamber (RC), a hybrid electromagnetic compatibility (EMC) testing facility is designed and constructed. Generally, the lowest usable frequency (LUF) of an RC is limited by its dimension, which limits the application of RCs for EMC testing at low frequencies. Therefore, to improve the field uniformity (FU) of an RC at frequencies lower than the LUF, a TLS is integrated into the RC. After optimizing the load resistance, length, and width of the TLS, the resonant frequency and electric field spikes of the hybrid system are eliminated. The FU of the E-field in the system is greatly improved in the frequency range of 0-30 MHz. Moreover, using an oscillating wall stirrer in the RC, the FU satisfies the standard (IEC 61000-4-21) above 80 MHz. Results show that combining the TLS and the RC testing system could be widely used for EMC testing in the frequency range of 0-30 MHz and 80 MHz-6 GHz.

Crosstalk Analysis of Printed Circuit Board Traces With Right-Angled Bent Corners via Time Domain Hybrid Method

Discontinuous impedance exists when bent corners are introduced into the traces of printed circuit board (PCB). By combining transmission line (TL) equations, higher order finite-difference time-domain (FDTD) method, state variable method, and Norton's theorem, an efficient time domain hybrid method is proposed to realize the fast crosstalk simulation of the traces with right-angled bent corners (RABCs) in this work. First, the whole structure of the traces is decomposed into a cascade network, which consists of multiple equal length parallel microstrip lines (EL-PMSLs) and the RABC structures. Then, the crosstalk responses on these EL-PMSLs can be quickly solved by applying TL equations combined with the higher order FDTD method. With the application of Norton's theorem, the equivalent circuit model of whole PCB traces is constructed. Finally, the equivalent circuits of the RABC structures are extracted, and the port voltages of these RABCs are calculated via state variable method and fed back to these EL-PMSLs as boundaries, thus the round-trip transmission of interference signals on the PCB traces is realized. Numerous crosstalk simulations of PCB traces with typical RABC structures, as well as extracted from a practical PCB, are presented and compared with the results of commercial software CST to verify the correctness and efficiency of the proposed method.

Preconceptual Design of the Port Cell Section for the EU DEMO Equatorial EC System

The EU demonstration power plant (DEMO) Tokamak will be equipped with an electron cyclotron (EC) system for plasma heating and magnetohydrodynamic (MHD) control. Up to six launchers will be installed into equatorial ports with the aim to inject maximum 130-MW millimeter-wave (mm-wave) power at dedicated positions into the plasma. The mm-waves will be generated in gyrotrons placed in a distinct building at distant location. From this gyrotron hall, a combined transmission line (TL) system of quasi-optical multibeam mirrors and individual waveguides (WGs) will propagate the mm-waves into the tokamak building. That followed, an optical system, composed of miter bends, diamond windows, valves, and microwave bellows, connects the TL through the gallery and the port cell with the EC launchers. This article presents the preconceptual computer-aided design (CAD) of this latter section of the EC system. Based on its general scheme and the given WG trajectories, the model takes into account the available space in the port cell with respect to required clearance for supply systems, assembly, and maintenance. At the preconceptual state, the design includes CAD models of all relevant mm-wave components in realistic dimensions at a level of details, appropriate to demonstrate the feasibility of the concept.

Application of frequency optimization neural network method on power line communication

The quality of broadband power line carrier communication mainly depends on the carrier communication frequency. However, there is a lack of fast and effective optimal carrier frequency selection method. One frequency selection method based on frequency point optimization neural network is proposed by this paper. This method combines transmission line theory and voltage partial reflection theory to build a power line carrier channel mathematical model of the distribution network. The input frequency point sample set is used as the training set of the frequency point optimization neural network to obtain a neural network model that can predict the local optimal frequency point set. Then the actual distribution network is taken as an example for simulation analysis. When inputting any frequency range, the model outputs the corresponding optimal frequency point set. Simulation results show that the algorithm saves a lot of input impedance or channel strength testing time, while the error rate is limited to about 3%.

A Combination of Transmission Line Models as Design Instruments for Electromagnetically Coupled Microstrip Patch Antennas in the 2.45 GHz ISM Band

This communication presents an analytical framework that combines transmission line models for the design of electromagnetically coupled microstrip patch antennas for the 2.45 GHz industrial, scientific, and medical band. It provides initial values for all dimensions of the antenna, with measured resonance frequency errors below 6%. The initial design is optimized in two subsequent phases to center the resonance frequency and to increase the impedance bandwidth (BW), obtaining measured resonance frequency errors below 0.6% and BW enhancements of more than 1.2 times the original ones, respectively. The model has been validated with antenna prototypes based on rigid and textile materials, exhibiting excellent free-space measured BW of 4% and 5.12%, maximal measured gains of 4.28 and 7.33 dBi, and radiation efficiencies of 63.4% and 71.8%, respectively. Moreover, very stable on-body performance is obtained, with minimal frequency detuning when deploying the textile antenna on the human body. The measured maximum on-body gain for the textile antenna equals 5.5 dBi, with a simulated specific absorption rate of 0.323 W/kg at 2.45 GHz.

Methodology for Analyzing ESD-Induced Soft Failure Using Full-Wave Simulation and Measurement

An analysis methodology is presented to investigate soft failures in electronic devices. This methodology combines transmission line pulse (TLP) full-wave simulations with system-level and TLP measurements. Information on susceptible parts in the device under test (DUT) and/or soft failure sensitivity of the integrated circuits (ICs) are obtained from the measurements. Then, the TLP current spreading within the printed circuit board (PCB) of the DUT is simulated. The susceptible signals can be determined by comparing the simulated voltages and/or currents at the signal terminations with the measured threshold values. If the simulated voltages and/or currents are higher than the threshold values, the signal is considered susceptible and a soft failure may occur in the DUT. Using the obtained information from simulations and measurements, the root causes of soft failures can be identified. Further, by utilizing full-wave simulations, the design of the product can be modified to reduce the electrostatic discharge (ESD) noise on the susceptible signals, and consequently prevent soft failures. The proposed analysis methodology is applied to a tablet which suffers from soft failure. The root cause of the soft failure is identified, and countermeasures are designed against the ESD-induced soft failure.

Multi‐layer power system tearing methodology for EMT‐TS hybrid parallel simulation

Due to the fast development of UHVDC, the power transferring through HVDCs takes a great part of the power from West China to East China. The response for multiple-coupled HVDCs can only be simulated through EMT programmes. To increase the simulation accuracy, the EMT-TS Hybrid simulation has been used in studies of the power system operation. Currently, the EMT-TS hybrid simulation speed is too slow to be unaffordable. This paper presents a novel power system tearing technology to greatly improve the simulation speed in EMT-ST Hybrid Simulation. The TS network is teared according to obtain network islands as many as possible, while the EMT network is teared through the combined transmission line and electric nodes. An algorithm is supposed to form the EMT-ST sub-network groups, which has no coupling with each other. Then, a novel parallel programme structure is proposed to use this EMT-ST sub-network groups to realise the parallel simulation and speedup the simulation. The case studies of the grids with seven HVDCs and 3000 nodes show that the proposed method could greatly improve the simulation speed without lowering precision.

Two-terminal AF location scheme for multi-segment combined transmission lines using unsynchronized measurements

Arcing faults (AFs) have probabilistic and nonlinear nature which is related to environmental parameters. Thus, the conventional fault location methods can not locate the AFs, accurately. This article puts forward a novel and precise AF location technique for multi-segment combined transmission lines which uses unsynchronized measurements from two terminals of the line. The method consists of stages; the number of them is equal to the number of segments plus one. This scheme does not need to employ a selector to identify the faulty segment of the line. Finally, the case studies are carried out using MATLAB/Simulink with variations of fault conditions including fault distance, type, incidence angle and faulty segment of the line, and also with variations of synchronization angle which show that the presented method provides a high accuracy in AF location under various situations.

Study of the effect of atmospheric overvoltages on overhead lines of medium voltage classes

The article is devoted to the effect of atmospheric overvoltages on the operation of overhead lines of electrical distribution networks with protected and bare wires. The article deals with the methods of protection and their effectiveness in lightning storms used in Ukraine and in the world. The influence of lightning and line parameters on the probability of a direct lightning strike in the overhead line is considered. The technique for calculating direct lightning strikes in a line is analyzed. A new approach to the simulation of overhead lines affection by direct lightning strikes is applied by modeling the height of the orientation of the lightning. It is described the creation of a large-scale model for conducting experimental studies, with the possibility of changing the parameters of lightning (lightning current) and overhead line parameters (line voltage, type of wire). The data allowing to determine the zone of the zipper capture for the lines with the protected wires and the bare wires by the experimental method are obtained. Due to the obtained data, it is possible to more accurately determine the number of direct lightning strikes in overhead lines. The possibility of creating an overhead transmission line using a combination of bare wire and protected wires is considered. With this configuration, the striking effect of lightning on bare wires will be significantly reduced, and the bare wire in addition to the phase conductor will act as a lightning protection cable. An experimental model of a combined power transmission line has been created and its effectiveness has been experimentally confirmed. Conclusions are made about the possibility of using an overhead power line with combined wires for medium voltage classes

A Study on the Development of a Fault Location Algorithm in Combined Transmission Lines using Fault Recording Data

Recently, combined transmission lines have been increasing according to technological development and rapid urbanization. Protection schemes for combined transmission lines are therefore required. Auto reclosing is the protection scheme widely used to protect transmission lines and is therefore also applied to combined transmission lines. However, caution is required when reclosing a combined transmission line because this involves an underground cable line. The fault on the cable line is permanent, which can cause serious problems when reclosing, and therefore reclosing for the fault on the cable line is prohibited. In a combined transmission line, then, fault location is an important factor in applying auto reclosing, requiring close consideration.BR In this paper, a simple fault location algorithm is proposed using the difference between fault occurrence time and voltage fluctuation time when disturbance occurred. The proposed algorithm solely uses the DFR’s fault recording data so it has the advantage of being a very simple method. In this paper, the proposed algorithm is verified by various simulation conditions using an ElectroMagnetic Transient Program (EMTP).

A laser-assisted process to produce patterned growth of vertically aligned nanowire arrays for monolithic microwave integrated devices

An experimental process for the fabrication of microwave devices made of nanowire arrays embedded in a dielectric template is presented. A pulse laser process is used to produce a patterned surface mask on alumina templates, defining precisely the wire growing areas during electroplating. This technique makes it possible to finely position multiple nanowire arrays in the template, as well as produce large areas and complex structures, combining transmission line sections with various nanowire heights. The efficiency of this process is demonstrated through the realisation of a microstrip electromagnetic band-gap filter and a substrate-integrated waveguide.

Cross‐bonding cable and box model based on pulse reflection measurement

Transients from lightning strikes can enter underground cables at overhead line to power cable transitions. Possible overvoltages on these surges at cross-bonding connections of the cable screens are of major concern. A model is developed for modelling overvoltages from transient signal propagation through a combined cross-bonding cable and box. This model is applied to the first Dutch 400 kV cable connection. Such model incorporates model parameters whose values depend on design details of the cross-bonding box. The values for these model parameters are extracted from the measured transmission and reflection signal on steep pulses injected into the actual cross-bonding box configuration. The model combines transmission line description for the cross-bonding cables with mainly inductive behaviour of the cross-bonding box. The obtained results are verified by measurements. The model is applied to investigate overvoltages induced at the cross-bonding cable and box on 1.2/50 ?s impulse voltage injection representing a lightning impulse voltage applied to the core conductor of the cross-bonding cable. Furthermore, the effectiveness of surge arresters to reduce overvoltages at the cross-bonding cable screen is demonstrated by simulations with this model in PSCAD.

A new single ended fault location algorithm for combined transmission line considering fault clearing transients without using line parameters

In this paper a new single ended fault location method is proposed for underground cable combined with overhead lines. In this algorithm fault clearing high frequency transients are used instead of fault-generated transients and the line parameters are not needed. In the proposed algorithm, samples just from voltage transients generated by fault clearing action of circuit breaker are taken from the sending end of the cable line. Applying wavelet transform, the first three inceptions of traveling waves to the fault locator are detected. Using these, the proposed algorithm at first identifies fault section, overhead or cable, and then wave speed is calculated and at last location of fault is determined accurately. Because of using only voltage samples taken from one terminal, it is simple and economic and does not need to GPS and data communication and synchronization. Extensive simulations carried out using SimPowerSystem toolbox of MATLAB, confirm the capabilities and high accuracy of the proposed method under different system and fault conditions.

345kV급 가공송전선로와 GIL이 연계된 혼합송전계통에서 개폐과전압 해석 및 검토

This paper describes switching surge analysis for reclosing decision in 345kV combined transmission line with GIL. Reclosing operation should be decided based on the detailed technical analysis in combined transmission line because this line includes power cable section which is week on insulation. Insulation of power cable can be breakdown at the week point in case of reclosing moment. Therefore the detailed analysis has to be carried out by considering several conditions such as charging rate, inserting resistance, arrester, length ratio of power cable section, grounding resistance, etc. Analysis is performed by EMTP/ATP.

A 16-kV HBM RF ESD Protection Codesign for a 1-mW CMOS Direct Conversion Receiver Operating in the 2.4-GHz ISM Band

A decreasing-sized π -model electrostatic discharge (ESD) protection structure is presented and applied to protect against ESD stresses at the RF input pad of an ultra-low power CMOS front-end operating in the 2.4-GHz industrial-scientific-medical band. The proposed ESD protection structure is composed of a pair of ESD devices located near the RF pad, another pair close to the core circuit, and a high-quality integrated inductor connecting these two pairs. This structure can sustain a human body-model ESD level higher than 16 kV and a machine-model ESD level higher than 1 kV without degrading the RF performance of the front-end. A combined on-wafer transmission line pulse and RF test methodology for RF circuits is also presented confirming previous results. The front-end implements a zero-IF receiver. It has been implemented in a standard 2P6M 0.18-μm CMOS process. It exhibits a voltage gain of 24 dB and a single-sideband noise figure of 8.4 dB, which make it suitable for most of the 2.4-GHz wireless short-range communication transceivers. The power consumption is only 1.06 mW from a 1.2-V voltage supply.

EMTP/ATPDraw를 이용한 가스절연송전선로(GIL)의 과전압 분석

Nowadays, it is becoming difficult to secure a transmission line route when a new transmission line is constructed due to social environment and resident complaints. As existing urban areas are expanded and new cities are constructed, the necessity of high-capacity underground power transmission has been increasing because of load concentration in downtown areas. In North America, Europe and Japan, the research has been carried out for 2nd generation gas insulated transmission lines(GIL) which is more environmentally friendly and economical compared to previous GILs. The new GILs have been applied to real power systems from early 2000s. In South Korea, GIL is being considered as a possible solution for replacing 345kV high-capacity overhead transmission lines with underground transmission ones, so KEPCO is planning to develop and apply a new 362kV rated GIL underground transmission lines instead of overhead transmission lines. In this paper, the overvoltage generated at the combined transmission line adapting GIL was reviewed using EMTP.

154㎸ 혼합송전선로 재폐로 결정에 관한 연구

This paper describes switching surge analysis on reclosing decision in 154㎸ combined transmission line with power cables. Reclosing should be operated in combined transmission line based on the technical evaluation because of insulation problem of power cable section. If the surge strikes on power cable, the breakdown can occur at week point of cable insulation. Therefore the detailed analysis is required by considering several conditions such as length ratio of power cable, arrester, fault resistance, charging rate and grounding resistance, etc.. In addition, sheath voltage on IJ(Insulated Joint) is analyzed to confirm the protective level. Simulation is performed by EMTP/ATP. Analysis results show that reclosing can be operated without any special problem by the single line-to-ground fault with fault resistance of 1Ω to 50Ω occurred at the overhead transmission section in 154㎸ combined transmission lines and trap charge of 100% and 110%.

Effects of Reclosing for Insulation Coordination in 345kV Combined Transmission Lines

This paper describes switching surge analysis for reclosing decision in 345kV combined transmission line with XLPE power cable. Reclosing operation should be decided based on the detailed technical analysis in combined transmission line because this line includes power cable section which is week on insulation. Insulation of power cable can be breakdown at the week point in case of reclosing moment. Therefore the detailed analysis has to be carried out by considering several conditions such as length ratio of power cable section, arrestor, inserting resistance, charging rate, grounding resistance, etc.. On the other hand sheath voltage on IJ(Insulated Joint) is analyzed to check dangerous condition on cable cover. Analysis is performed by EMTP/ATP. Analysis results show that reclosing can be operated as the single line-to-ground fault occurs on overhead line in 345kV combined transmission line, if the inserting resistance is considered before the operation of main circuit breaker.