Transmission Line Network Research Articles

Design of a free space metamaterial lens based on LC parameters at S-band

A metamaterial lens was designed based on a two-dimensional host transmission line network loaded with inductors and capacitors. The planar negative refractive index (NRI) periodic structure, consisting of a unit cell array with a concave side, works as a curved lens matched to free space operating at S-Band. An equivalent unit cell dispersion relation was developed to determine the transmission characteristics at the operating frequency range. The challenge in the metamaterial lens design is to increase the focal distance. In the simulated system, a high energy level throughout a focal region was observed in the whole frequency range. An equivalent bulky material is used as a resource to reduce computational effort.

Analysis of the Response of Transmission Line Network under Electromagnetic Pulse

Power system transmission line is a very complex network. The response of cable terminal is very different from that of single line. In order to accurately predict the terminal response of the cable under the nuclear electromagnetic pulse, a convenient method is needed to calculate the response of complex network. Based on the state equation method and the extrapolation method, the transmission line is equivalent to the current source or voltage source. Matlab program and Simulink are used to calculate the induced current generated by the cable terminal. The results are compared with those of CST cable studio. The results of CST show that the method is correct.

Localization of a Discharge in Transmission Line Networks using Time Reversal with TLM

The location of an electrical discharge in a transmission line network is found from its recorded transient response by means of a time reversal simulation. The accuracy of the localization procedure depends on how closely the simulator models the wave properties of the network that must be linear, reciprocal, and virtually loss-free. TLM simulations are presented.

EMI Analysis of Multiscale Transmission Line Network Using a Hybrid FDTD Method

A hybrid time-domain numerical method based on the full wave finite-difference time-domain (FDTD) method combined with a modified 1-D FDTD method has been proposed to analyze the electromagnetic interference (EMI) of multiscale transmission line networks in a metallic cabin in this article. This method is implemented through two numerical solvers for full wave and transmission line simulations, respectively, by adopting a set of reasonable physical boundary conditions between external fields and transmission line network. By using Ampere's law, the external fields can be transferred to a voltage source that can be further used as the forcing terms in the telegraph equation of the transmission line network. To overcome the challenge introduced by the multiscale size of the transmission line network, we combine 1-D explicit and implicit FDTD methods together to solve the coaxial cables and interconnects in PCB, respectively. Thus, among different subdomains, the hybrid method can be carried with the same time step without the restriction of the stability condition. Numerical examples show the accuracy as well as efficiency of the proposed method compared with the HSPICE and traditional FDTD method. In addition, the method is used successfully in analyzing the EMI effects of a complex transmission line network inside a cabin illuminated by external electromagnetic wave.

Fault Detection and Protection Schemes for Distributed Generation Integrated to Distribution Network: Challenges and Suggestions

The use of distributed generation has received wide attention due to low maintenance costs, reduced transmission line losses and network congestion, as well as minimal impact on climate change and global warming. However, the distributed generation integrated to the distribution network introduces various protection problems that cannot be solved by conventional protection systems. These obstacles include the bi-directional power flow and the variation in the fault current level during the topology change. Thus, appropriate fault detection and protection scheme are strongly recommended to increase safety and reliability of the distributed network. This paper presents a comprehensive overview of the distributed network fault detection and protection strategies incorporated with distributed generation. This review also investigates the various fault detection approaches concerning types, communication methods, operation mode, constraints and benefits. Additionally, numerous island detection techniques are explored, focusing on generation types, parameters, cost and advantages. Moreover, the review outlines the various protection schemes highlighting categories, operation, constraints, strength and shortcomings. The key issues and challenges are discussed along with selective proposals for future research. All the highlighted viewpoints of this research will hopefully be beneficial to power system engineers and researchers for the advancement of distributed network fault and protection strategies for suitable operation and management of future distributed generation systems.

Identification of Composite Insulator Criticality Based on a New Leakage Current Diagnostic Index

In this article, a new method is proposed to identify the health condition of composite insulators through investigating the leakage current (LC) along with the electric potential (EP) and electric field stress (EFS) profiles. In this regard, variations of the LC harmonics and the distribution profiles of the EP and EFS are investigated through a series of experimental and simulation analyses conducted on composite insulators under various environmental and pollution conditions. Fast Fourier transform (FFT) and a COMSOL-multiphysics environment are utilized to analyze this variation. The results reveal a strong correlation between the LC harmonics and the insulator health condition. A new diagnostic criticality index based on the third to the fifth harmonic ratios of the insulator LC is proposed to quantify the composite insulator criticality and predict the likelihood of flashover occurrence. The EP and EFS analyses can be used to provide a complementary diagnosis of the insulator's health state under severe pollution and humidity conditions. The proposed analysis enables the transmission line network operator to get an insight into the insulators' functional status, thus improving the network reliability through avoiding insulator failure and adopting a proper condition-based maintenance scheme.

Synthesis design of wideband bandpass filter with narrow notch band

AbstractIn this article, a novel wideband bandpass filter (BPF) with narrow notch band is presented. It is composed of two sets of shunt microstrip‐to‐slotline vertical transitions, a coplanar waveguide (CPW) connecting line, and a meandering half‐wavelength slotline section. Utilizing the synthesis method based on the transmission line network, a four‐pole BPF with Chebyshev equal‐ripple frequency response is realized in the desired passband. The narrow notch band with 3‐dB fractional bandwidth (FBW) of 3% at the center frequency 2.75 GHz is introduced by an embedding meandering slotline stub. To verify the theoretical prediction, the proposed BPF is fabricated and measured. The circuit model and EM simulation are consistent with theoretical calculation and test results, which sufficiently confirm the correctness and feasibility of the design method.

Transporting Biodiversity Using Transmission Power Lines as Stepping-Stones?

The most common ecological response to climate change is the shifts in species distribution ranges. Nevertheless, landscape fragmentation compromises the ability of limited dispersal species to move following these climate changes. Building connected environments that enable species to track climate changes is an ultimate goal for biodiversity conservation. Here, we conducted an experiment to determine if electric power transmission lines could be transformed in a continental network of biodiversity reserves for small animals. We analysed if the management of the habitat located inside the base of the transmission electric towers (providing refuge and planting seedlings of native shrub) allowed to increase local richness of target species (i.e., small mammals and some invertebrates’ groups). Our results confirmed that by modifying the base of the electric transmission towers we were able to increase density and diversity of several species of invertebrates and small mammals as well as number of birds and bird species, increasing local biodiversity. We suggest that modifying the base of the electric towers would potentially facilitate the connection of fragmented populations. This idea would be easily applicable in any transmission line network anywhere around the world, making it possible for the first time to build up continental scale networks of connectivity.

Protection scheme for hybrid transmission system using fuzzy inference system and microcontroller

This paper presents a fuzzy inference system and microcontroller-based protection scheme for a combined underground (UG) cable and overhead (OH) transmission line system. The scheme detects, classifies, and locates the fault occurring either in an UG cable or OH transmission line network. Furthermore, the scheme identifies the faulty section. An existing Indian power network i.e., real power system network of C.G. state, consisting of 132 kV, 50 Hz power transmission network connecting Doma substation 220/132 kV to the 132/33 kV Gas Insulated Substation Rawanbhata through combined transmission network is considered. This real power transmission network is simulated by using MATLAB/Simulink software. In this paper, the hardware implementation is also carried out using an open-source hardware, Arduino, which consists of an Atmel 8-bit AVR microcontroller. Both the simulation and hardware results validate that the proposed scheme is accurately detecting, classifying, and locating the fault in less than a half cycle time. Moreover, the percentage error in determining the location of a fault is less than 0.7%.

Investigation of the plane wave coupling to a linearly loaded transmission line network

The article is concerned with a complex investigation of the influence of the plane wave coupling with a certain function of time, incident direction and polarization to a linearly loaded transmission line network comprised of three single-wire conductors with different lengths connected in the center. Line load is represented as 50 Ω resistors connected to all terminations of the transmission line network. The exemplary network was modeled on a computer and experimentally investigated in a gigahertz transverse electromagnetic GTEM cell, which allows creating an electromagnetic field of a certain direction. The coupled voltage at the terminals of the network was investigated in the frequency and time domains. To conduct an experiment in the frequency domain, both to create an electromagnetic field inside the GTEM camera and to measure the induced voltage at the terminations of the network, a vector network analyzer VNA was used. To conduct an experiment in the time domain for the sake of creating an electromagnetic field, a high-voltage voltage generator was used, whereas a strobing oscilloscope was used to measure the induced voltages. The simulation was performed in the LTspice software - a tool for calculating electrical and electronic circuits, and Matlab. It is also examined to show the compliance with the experimental results. On the basis of obtained results, the author was able to identify the main aspects that may be useful in modeling and predicting the electromagnetic processes occurring in linearly loaded conductors, power supply and / or data transmission systems.

Fault classification in power system distribution network integrated with distributed generators using CNN

Fault detection is the critical stage of the relaying system and their successful completion in minimum time is expected for fault clearance. With the increasing usage of distributed generators (DGs) in a distribution network, the conventional relaying methods are becoming inappropriate due to changing fault current levels. This paper presents a deep learning algorithm i.e. Convolutional Neural Network (CNN) customized for fault classification in the distributed networks integrated with DGs. This is first time that CNN has been used for fault detection using raw and sampled-data of three-phase voltage and current signals of various fault classes and no-fault class. The 10-fold cross-validation is used to demonstrate the performance of the proposed model in terms of different metrics such as accuracy, sensitivity, specificity, precision, and F1 score. The proposed model has attended an average 10-fold cross-validation accuracy of 99.52% for all the tested fault cases. This featureless proposed method has been compared with conventional approaches from literature and has shown better performance in terms of accuracy and computation burden. Further, a similar fault study is conducted on a mixed transmission line and distribution network with PV as DG using the proposed method and found performance accuracy of 99.92% and 99.97%, respectively.

Compact wideband microstrip‐slotline bandpass filter with sharp selectivity and suppressed spurious harmonic

AbstractA novel compact wideband microstrip‐slotline bandpass filter (BPF) with roll‐off cutoff slop and extended upper stopband is proposed, which consists of two cascaded microstrip‐to‐microstrip vertical transitions. Under the influence of interdigital capacitor, a pair of transmission zeros (TZs) at both sides of passband are generated to effectively enhance shirt selectivity, the mechanism of cross‐coupling structure is theoretically interpreted in detail based on equivalent transmission line network. In order to well suppress the upper stopband spurious harmonic, there are additional five TZs are introduced by properly adjusting the electrical length of open‐ended slotline sections and etching a set of spurlines on the feeding lines. For experimental validation, two broadband BPFs with/without spurlines are designed, fabricated, and measured. The measured results demonstrate that the BPF with spurlines have more excellent electric performances compared with the one without spurlines. The return loss ≥17.38 dB, insertion loss ≤0.82 dB with the 3‐dB fractional bandwidth (FBW) of 134.52%, the extended upper stopband is up to 3.86 times center frequency with rejection level better than 20.63 dB, the spurious harmonic is significantly suppressed without increasing additional circuit dimension, the compact effective circuit size is only 0.95λg*0.29λg, λg is guided wavelength at center frequency. Finally, the theoretical analysis is well verified by measured and simulated results, excellent agreement between them is achieved.

GIS bio-waste assessment and suitability analysis for biogas power plant: A case study of Anambra state of Nigeria

Environmental concerns have increased over environmental hazards associated with fossil energy source, transition to renewable energy sources have been emphasized, this however requires relevant data for informed decision making. Critical analytical methods in situating bioenergy plants for bioenergy production are advantageous from environmental, economic and sustainable perspectives. A study therefore was undertaken to provide relevant data on biogas renewable energy source using Anambra State of Nigeria as a case study. The study was carried out using the power of Geographical Information System (GIS) technology. Several GIS thematic layers were obtained considering important factors in bioenergy plant location analysis. GIS-based thematic maps used for the production of the suitability map include political boundary map layer, road network layer, Land Use and Land Cover (LULC) layer, Digital Elevation Map (DEM) layer, river layer, slope layer, electric transmission line network layer, biomass potential density layer etc. Considering the fact that bioenergy plant is dependent on heat energy source which is also abundant in the tropics, hill-shade layer was integrated into the GIS location suitability analysis. Various economic and socio-environmental factors were considered and utilized in the development of economic, land suitability and bio-resource spatial density maps. These thematic maps were overlaid to obtain the final suitability map index. The most suitable sites identified were located in Njikoka, Onitsha North and Dunukofia Local Government Areas (L.G.As) of the Study area. The annual cumulative bio-wastes generated from the three LGA are 9,133,220 kg, 3,992,735 kg, and 6,909,450 kg respectively. It is recommended that government and stake-holders should take this study as a veritable tool in green energy technology implementation plan.

A Closed Time-Reversal Cavity for Electromagnetic Waves in Transmission Line Networks

A closed time-reversal (TR) cavity has been considered a purely theoretical concept whose experimental realization was assumed to be impossible. In this article, we demonstrate that it is, in fact, possible to realize a closed TR cavity using a network of transmission lines. The network is excited by either lumped voltage or current sources at arbitrary locations, and it is terminated on matched impedances. This system is an exact closed TR cavity in the sense that, in the backward-propagation stage, by back-injecting time-reversed measured responses (voltage or current) generated by a source at each line terminal, a time-reversed copy of the current and voltage distribution in the forward-propagation stage is obtained. We report for the first time an experimental realization of a TR cavity formed by a network of inhomogeneous transmission lines, in which the spatial and temporal signal distribution along the network is reproduced as in a sequence of the system state (i.e., voltages and or current along the lines) being played in reverse. We also discuss the interfering effect of the so-called diverging wave for observation points in the vicinity of the source. An active realization of a TR sink is proposed to effectively overcome the interfering effect caused by the diverging waves.

Integrating Dynamic Line Rating in Security Constrained Optimal Power Flow Considering Wind Power Generation. (Dept. E )

Traditional optimal power flow (OPF) problem is solved considering static line rating (SLR) of the transmission lines which are constant values of power flow limits. This led to underutilization of the network and higher locational marginal prices (LMPs). Dynamic line rating (DLR) is one of the active solutions to enhance ampacity for overhead transmission lines (OHTL), especially with the penetration of high wind power without investing in an additional transmission line network. This paper investigates the effect of integrating the DLR on power dispatch with uncertainty levels due to renewable energy sources (RES) generation. The model propose is a multi-period security-constrained OPF based on particle swarm optimization (SCOPF/PSO) that takes into consideration the steady-state heat-balance equation (SS-HBE) of the OHTL and the ramp-up time of generation units. The problem is a multi-objective optimization one; the main objective is to maximize the social welfare (SW) by minimizing total system operation cost and maximizing the revenue from the energy consumers, whereas the second objective is to minimize the thermal emissions. To demonstrate the effectiveness of the proposed model, a case study is applied to the modified IEEE 30-bus test system. The results expound on the effectiveness of the proposed approach.

Electromagnetic transient modeling of grounding electrodes buried in frequency dependent soil with variable water content

The increasing demand for electricity over the past few decades has been continuously urging for more reliable power systems. Power transmission line networks, due to their vast physical dimensions, are the most critical components of a complex power system concerning the direct lightning strike. Grounding systems are widely used to mitigate the transient overvoltages for the protection of electrical component and human safety. The goal of this paper is to investigate the effect of frequency dependence of soil electrical parameters on the performance of vertical and horizontal grounding electrodes subjected to direct lightning strike, considering a variable water content of soil. Four soil models that take into account the variation of soil water content are reviewed and compared. The numerical simulations are performed using a full-wave electromagnetic model based on the Finite Element Method (FEM) in the frequency range from 1 kHz to 5 MHz and applying different soil models with varying water content. Then, electromagnetic transient (EMT) compatible equivalent circuits of grounding electrodes are developed using Fast Relaxed Vector Fitting (FRVF). Typical first and subsequent return stroke current waveforms measured at two different locations are adopted. The results of this paper demonstrate the importance of considering the variation of soil water content in the transient response of grounding electrodes. Simulation results demonstrate that the frequency dependence of the soil parameters lead to a decrease of the potential rise of the grounding electrodes compared to the case where the soil parameters are assumed constant. The effect of soil water content on the grounding performance is also shown to be dependent on the soil type, value of soil water content, and length of electrode.

Corrections to “Time Domain Hybrid Method for the Coupling Analysis of Oblique Transmission Line Network Excited by Ambient Wave”

In [1], Fig. 5 is incorrect. The correct figure is provided as follows. Fig. 5. Interpolation scheme for the electric fields at the starting or ending points of each segment of oblique transmission line.

A Structural Characterization of Market Power in Electric Power Networks

We consider a market in which capacity-constrained generators compete in scalar-parameterized supply functions to serve an inelastic demand spread throughout a transmission constrained power network. The market clears according to a locational marginal pricing mechanism, in which the independent system operator (ISO) determines the generators' production quantities to minimize the revealed cost of meeting demand, while ensuring that network transmission and generator capacity constraints are met. Under the stylizing assumption that both the ISO and generators choose their strategies simultaneously, we establish the existence of Nash equilibria for the underlying market, and derive an upper bound on the allocative efficiency loss at Nash equilibrium relative to the socially optimal level. We also characterize an upper bound on the markup of locational marginal prices at Nash equilibrium above their perfectly competitive levels. Of particular relevance to ex ante market power monitoring, these bounds reveal the role of certain market structures---specifically, the \emph{market share} and \emph{residual supply index} of a producer---in predicting the degree to which that producer is able to exercise market power to influence the market outcome to its advantage. Finally, restricting our attention to the simpler setting of a two-node power network, we provide a characterization of market structures under which a Braess-like paradox occurs due to the exercise of market power---that is to say, we provide a necessary and sufficient condition on market structure under which the strengthening of the network's transmission line capacity results in the (counterintuitive) increase in the total cost of generation at Nash equilibrium.

Time-Domain Software Correction of Nonlinear Faulty Lossy Transmission Line Networks

In this article, we use Newton's method and the nonlinear least squares method to solve a nonlinear problem in electromagnetic compatibility. Both techniques provide a way to identify the temporal profile of a voltage source that would produce a target voltage over a given time interval at a point of the transmission line network presenting nonlinear components. After comparing the results of a test problem, the most efficient method is considered to identify the temporal source in order to bring a software correction to a nonlinear faulty lossy transmission line network. The software correction process may cancel any unintentional perturbations produced by one or more faults regardless of their type and location.

Implementation of a compact dual-band bandpass filter using signal interference technique on paper substrate

This paper exhibits the design and implementation of a compact dual-band bandpass filter on paper substrate. The proposed filter which works on the principle of signal interference technique has a parallel combination of short-circuited coupled line and an H-shaped network of transmission lines with open stubs. Due to the superposition of signals of the two transmission paths, a second order dual-band bandpass response with four transmission zeroes is achieved. To validate the proposed design, theoretical analysis using the lossless transmission line model is carried out and acknowledged. The developed dual-band filter prototype with center frequencies 1.17 GHz and 4.06 GHz has 3-dB fractional bandwidths of 82.56% (0.69–1.656 GHz) and 20.59% (3.645–4.481 GHz), respectively. The simulated and experimental results are in good congruence with each other. The proposed dual-band bandpass filter can be used in various wireless applications, for example, Global System for Mobile Communications (880–915 MHz), Aircraft surveillance (960–1215 MHz), Indian Regional Navigation Satellite System (1.164–1.188 GHz), Amateur radio (1.24–1.30 GHz), Global Positioning System (1.559–1.61 GHz), Satellite phones (1.616–1.626 GHz), and Satellite communication (3.7–4.2 GHz).