Single Transmission Line Research Articles

Feasibility of DSR applications in transmission grid operation—Control of power flow and imbalanced voltage

Distributed Series Reactors (DSRs) can be used to control power flow to more fully utilize the capacity of a transmission network, delaying investment in new transmission lines. In this paper the IEEE 39 bus standard test system is modified to a 3-phase, unbalanced model consisting of 230kV, 345kV and 500kV lines, where lines of different voltage run in parallel. This model is used to study load growth and the effect of adding DSRs to alleviate resulting overloads, and in particular to alleviate overloads on lines of different voltage running in parallel. The economic benefit of adding DSRs to the network is compared to the addition of new transmission lines in the network. In the second part of the paper the effect of unsymmetrical operation of DSRs on a single transmission line is studied and compared to the symmetrical operation of DSRs. It is found that unsymmetrical operation of DSRs is more economical. Finally the unsymmetrical operation of DSRs to reduce voltage imbalance in the network is considered.

Electric transmission lines: Control and numerical discretization

We are interested in the mathematical modeling and control of electrical power lines. The electric transmission lines under consideration are modeled as directed graph. The evolution of voltage and current is described by a linear 2 2 system of hyperbolic balance laws. Open and closed loop control concepts are investigated for control actions at nodal points in the network. For the modeling of electric transmission lines several mathematical approaches can be found in the literature [1, 3]. A typical control problem is to find the optimal power flow when allowing for power supply at selected nodes. Mathematically, this leads to possibly large scale finite-dimensional nonlinear optimization problem [4]. From those, simplified models are derived, which use linear or mixed-integer programming techniques to determine the optimal flow [7]. Based on those models extensions to oscillator networks are used to capture some effects of time-dependent transmission lines. A typical model for the evolution is given by the spatially one-dimensional telegraph equation supplemented by suitable source terms. For instance, in [9] the power and signal losses in communication systems are determined by the telegraph equation. Depending on the sheeted material sometimes lossless transmission lines may be considered. In this case the telegraph equation reduces to the linear wave equation for the voltage. Mathematically, closed loop control questions for the wave equation have extensively been studied for example in [10]. Closed loop control of a single transmission line including source terms has been established using a Lyapunov function approach. We extend the existing result to more general networks and introduce coupling conditions for the telegraph equation as well. The idea is to derive a closed loop network control relying heavily on the construction of the suitable Lyapunov function for the telegraph equation. Furthermore, we introduce an open loop control concept and numerically compare the arising control actions. This extends recent investigations conducted for other applications [3, 11, 12].

A wide-band magnetic tunable bandstop filter prototype with FeGaB/Al2O3 multilayer films

In this paper, we demonstrate a prototype of magnetic tunable bandstop filter by using magnetic multilayers of [FeGaB 25 nm/Al2O3 5 nm]4 prepared by magnetron sputtering. The multilayer structure exhibits a relatively low coercive field and RF loss compared to the single layer film with the same thickness. By placing a single transmission line on the top of magnetic multilayers, a prototype of tunable bandstop filter was fabricated and operates from 4.5 GHz to 7.08 GHz under very low magnetic bias fields from 100 Oe to 400 Oe. These low loss multilayer films are good candidates for RF/microwave applications.

Power System Based Simulation Study ofUPFC in a Single Transmission Line System

As the complexity of the power system increases the necessity for carefully designed devices becomes a requirement to monitor and control the changes in the transmission line power flow. Unified Power Flow Controller (UPFC) is used in regulating the transmission line power flow by controlling impedance, voltage magnitude and phase angle. The working region of UPFC forms a locus within which it could be operated at any point to control the power flow in the system. This paper discusses the concept of operation of UPFC based on the above mentioned techniques distinctively. The locus of operation of UPFC is found to understand the region of operation for the connected load. The simulations are performed in MATLAB Simulink.

An analytical fault location method based on minimum number of installed PMUs

Summary In this paper, a new method is proposed for fault location using minimum number of phasor measurement units (PMUs) in a power network. In this method, all possible fault points over transmission lines are represented as virtual buses, and corresponding bus impedance matrices are calculated. Because capacitive property at the virtual buses is neglected, resulting impedance matrices are linear with respect to fault point distance. Using voltage data provided by PMUs and applying superposition theorem, potential fault points on every single transmission line are extracted, each by solving linear equations, and then, exact fault location is obtained using two predefined rules. In addition, fault type and fault impedance are determined by some criteria involving symmetrical components. Merits of the proposed method include simplified equations, thanks to linearity provided by omitting capacitive effect, as well as minimum required PMUs to be installed in the network. Besides, a set of fundamental rules describing PMU placement constraints, according to required voltage data of different points in the network, are introduced. Employing these rules ends up to a fewer number of required PMUs in comparison with other proposed methods. At the end of this paper, the accuracy of the suggested method has been evaluated by applying it on three test systems, namely Institute of Electrical and Electronics Engineers (IEEE) 30-bus, IEEE 39-bus, and IEEE 118-bus. Simulations, performed by MATLAB Simulink (MathWorks, Natick, MA, USA), indicate high accuracy and consistent results of the proposed method. Copyright © 2015 John Wiley & Sons, Ltd.

Modeling and Analysis of Crosstalk Induced Effects in Multiwalled Carbon Nanotube Bundle Interconnects: An ABCD Parameter-Based Approach

In this paper, the crosstalk effects in both small and large diameter multiwalled carbon nanotube bundle interconnects (MWCNTs) for the future nanoscale integrated circuits are studied with the help of ABCD parameter matrix approach for global levels of interconnects at 22- and 14-nm technology nodes. Here, isolated MWCNTs are modeled using an equivalent single conductor transmission line. The simulation results show that the results are at par with the result of SPICE model. It is observed that performance wise, the large diameter MWCNT bundles are better than both small diameter MWCNT bundles and copper wire for both repeated and unrepeated interconnects. The same trend is observed with the number of inserted repeaters. For repeated wires, the optimized placement of repeaters offsets the delay advantage numbers of MWCNT bundles over copper wire. Technology scaling adversely impacts the delay advantage numbers of small diameter MWCNT bundles. As far as the worst-case crosstalk noise peak voltage is concerned, the large diameter MWCNT bundles also outperform both small diameter MWCNT bundles and copper wire for longer interconnects. However, for shorter interconnects, copper wire and small diameter bundles outclass the large diameter bundles due to their relatively larger time constant. We have compared our crosstalk analysis results with the earlier work to justify the validity of our proposed model and observed that the results with our model are in well conformity with the existing work. It is seen that even the tall Cu vias are not going to significantly affect the performance of MWCNT bundle interconnects. Twice the minimum width global level interconnects are the optimal choice to achieve the maximum delay advantage using MWCNT bundle interconnects in comparison with Cu-based interconnects. Finally, our analysis shows that from the performance and signal integrity perspective, the large diameter MWCNT bundles are a suitable alternative to both small diameter MWCNT bundles and copper interconnects for future integrated circuit technology generations.

Intelligent-search technique based strategic placement of synchronized measurements for power system observability

Synchronized phasor measurements placement problem is commonly solved by formulating it as a mathematical optimization problem, which is limited by huge computational burden especially for larger systems. This paper proposes a novel intelligent search based approach for placement of phasor measurement units (PMUs) in the power system while maintaining complete observability. The proposed approach works in two stages. Stage I utilizes best first search to identify the possible locations of PMUs in order to obtain system observability and these locations are used as inputs to stage II. Stage II determines the optimal locations of PMUs by applying pruning to the inputs received from stage I, such that the system observability is achieved with the minimum number of PMUs. The proposed approach has been further extended to incorporate the presence of conventional flow measurements. An important feature of the proposed placement method is its capability to handle both single as well as multiple flow measurements connected to a bus. The proposed method has been tested on IEEE 14-bus, IEEE 30-bus and a practical 246-bus Indian networks for system intact condition as well as during single transmission line and single PMU loss. The effectiveness of the proposed method has been demonstrated by comparing the numerical results obtained using the proposed method with the existing methods.

Adaptive fault identification and classification methodology for smart power grids using synchronous phasor angle measurements

Smart power grids (SPGs) entail comprehensive real-time smart monitoring and controlling strategies against contingencies such as transmission line faults. This study proposes a novel methodology for identifying and classifying transmission line faults occurring at any location in a power grid from phasor measurement unit measurements at only one of the generator buses. The proposed methodology is based on frequency domain analysis of equivalent voltage phase angle and equivalent current phase angle at the generator bus. Equivalent voltage and current phase angles are the angles made by three-phase equivalent voltage and current phasors with respect to reference axis. These angles are estimated through Park's transformation and frequency domain analysis is performed over a fixed time span equal to inverse of system nominal frequency using fast Fourier transformation. The proposed methodology can be utilised for relaying purposes in case of single transmission lines as well as for system protection centre (SPC) applications in power grid. The significance of the fault information from the methodology is for assisting SPC in SPGs for transmission line fault detection and classification to restore the transmission lines at the earliest and initiate wide-area control actions to maintain system stability against disturbances generated by occurrence and clearance of fault.

Simulation, Modeling, and Analysis of Soliton Waves Interaction and Propagation in CNN Transmission Lines for Innovative Data Communication and Processing

We present an innovative approach to study the interaction between oblique solitons, using nonlinear transmission lines, based on Cellular Neural Network (CNN) paradigm. A single transmission line consists of a 1D array of cells that interact with neighboring cells, through both linear and nonlinear connections. Each cell is controlled by a nonlinear Ordinary Differential Equation, in particular the Korteweg de Vries equation, which defines the cell status and behavior. Two typologies of CNN transmission lines are modelled: crisscross and ring lines. In order to solve KdV equations two different methods are used: 4th-order Runge-Kutta and Forward Euler methods. This is done to evaluate their accuracy and stability with the purpose of implementing CNN transmission lines on embedded systems such as FPGA and microcontrollers. Simulation/analysis Graphic User Interface platforms are designed to conduct numerical simulations and to display elaboration results. From this analysis it is possible both to identify the presence and the propagation of soliton waves on the transmission lines and to highlight the interaction between solitons and rich nonlinear dynamics. With this approach it is possible to simulate and develop the transmission and processing of information within large brain networks and high density sensor systems.

Decision tree‐induced fuzzy rule‐based differential relaying for transmission line including unified power flow controller and wind‐farms

The paper presents a decision tree (DT) induced fuzzy rule-based intelligent differential relaying scheme for transmission lines including unified power flow controller (UPFC) and wind-farms. The conventional distance relaying scheme fails miserably in protecting transmission lines including flexible AC transmission systems controllers such as UPFC and further, the protection issues become more challenging when wind-farm is integrated. The proposed protection scheme extracts features from the instantaneous voltage and current signals from both ends of the transmission line using discrete Fourier transform based pre-processor and computes corresponding differential features. The differential features are used to build the fault classification tree using a data-mining algorithm known as DT. Further, the fuzzy membership functions are drawn using the DT thresholds and the corresponding fuzzy rule-base is developed for final relaying decision. The proposed technique has been extensively tested (in MATLAB environment) for single circuit and double circuit transmission lines including UPFC and wind-farms with wide variations in operating conditions. The test results indicate that the proposed DT-induced fuzzy rule-based relaying scheme is highly reliable and robust for protection of complex transmission line including UPFC and wind-farm.

A novel transmission line relaying scheme for fault detection and classification using wavelet transform and linear discriminant analysis

This paper proposes fault detection and classification scheme for transmission line protection using WT and linear discriminant analysis (LDA). Current signals of each phase are used for the detection and identification of faulty phases and zero sequence currents are used for the detection of ground. Current signals are processed using discrete wavelet transform with DB-4 wavelet up to level 3. Approximate coefficients are reconstructed using wavelet reconstruction. Performance of the proposed based scheme is tested by variations of parameters such as fault type, location, fault resistance, fault inception angle and power flow angle. The scheme is applicable for both single circuit and double circuit transmission line. All shunt faults and multi-location faults which occur in different locations at the same time are also detected and classified by the proposed scheme within one cycle time. The simulation results show that the proposed scheme is not affected by non-linear high impedance fault and CT saturation.

Plasmonic Grid Array of Gold Nanorods for Point-to-Point Optical Communications

A novel wire-grid array of nanorods is introduced. The array consists of five gold radiating rods and four gold perpendicular connecting rods. Each rod represents a plasmonic transmission line supporting single Surface Plasmon Polariton mode guided to the interface between the metal and surrounding dielectric. The propagation characteristics of this single strip plasmonic transmission line are studied using an integral equations formulation solved using the Method of Moments. The new array is designed for operation at a wavelength of 1.55 μm, which is commonly used by optical communication systems. The overall physical and electrical sizes of the array are (0.68-by-1.05 μm) and (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> -by-3λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> /2), respectively. The maximum directivity of the proposed wire-grid nantenna array on top of a substrate with refractive index of 2 reaches 15.24 dBi. The proposed wire-grid nantenna array has a symmetric radiation pattern with reasonable side-lobe-level and extremely low cross-polarization level.

Research on Frequency Electromagnetic Field of Parallel Transmission Line

At present the study mainly for frequency electromagnetic field which is based on a single transmission line meanwhile the value must be in line with the requirements of the workers in the country frequency electromagnetic field. However, for parallel transmission line the maximum of frequency electromagnetic field is still to meet the provisions of the state, therefore in this paper studied the parallel transmission lines. Taking the multiple parallel power lines of China Three Gorges University as an example, the values of electric and magnetic field are calculated and the electromagnetic field is measured based on National standards. Then, compare the measured value with theoretical value, verified the correctness of the superposition algorithm.

SU‐E‐T‐512: Electromagnetic Simulations of the Dielectric Wall Accelerator

Purpose:To characterize and parametrically study the key components of a dielectric wall accelerator through electromagnetic modeling and particle tracking.Methods:Electromagnetic and particle tracking simulations were performed using a commercial code (CST Microwave Studio, CST Inc.) utilizing the finite integration technique. A dielectric wall accelerator consists of a series of stacked transmission lines sequentially fired in synchrony with an ion pulse. Numerous properties of the stacked transmission lines, including geometric, material, and electronic properties, were analyzed and varied in order to assess their impact on the transverse and axial electric fields. Additionally, stacks of transmission lines were simulated in order to quantify the parasitic effect observed in closely packed lines. Particle tracking simulations using the particle‐in‐cell method were performed on the various stacks to determine the impact of the above properties on the resultant phase space of the ions.Results:Examination of the simulation results show that novel geometries can shape the accelerating pulse in order to reduce the energy spread and increase the average energy of accelerated ions. Parasitic effects were quantified for various geometries and found to vary with distance from the end of the transmission line and along the beam axis. An optimal arrival time of an ion pulse relative to the triggering of the transmission lines for a given geometry was determined through parametric study. Benchmark simulations of single transmission lines agree well with published experimental results.Conclusion:This work characterized the behavior of the transmission lines used in a dielectric wall accelerator and used this information to improve them in novel ways. Utilizing novel geometries, we were able to improve the accelerating gradient and phase space of the accelerated particle bunch. Through simulation, we were able to discover and optimize design issues with the device at low cost. Funding: Morgridge Institute for Research, Madison WI; Conflict of Interest: Dr. Mackie is an investor and board member at CPAC, a company developing compact accelerator designs similar to those discussed in this work, but designs discussed are not directed by CPAC.Funding: Morgridge Institute for Research, Madison WI; Conflict of Interest: Dr. Mackie is an investor and board member at CPAC, a company developing compact accelerator designs similar to those discussed in this work, but designs discussed are not directed by CPAC.

Forced Vibration of Overhead Transmission Line: Analytical and Experimental Investigation

An analytical model of a single line transmission line carrying a Stockbridge damper is developed based on the Euler–Bernoulli beam theory. The conductor is modeled as an axially loaded beam and the messenger is represented as a beam with a tip mass at each end. Experiments are conducted to validate the proposed model. An explicit expression is presented for the damping ratio of the conductor. Numerical examples show that the proposed model is more accurate than the models found in the literature. Parametric studies indicate that the response of the conductor significantly depends on the excitation frequency, the location of the damper, and the damper parameters.

Magnetic Field Calculation under Normal and Abnormal Conditions of Overhead Transmission Lines

Ground level magnetic field from overhead transmission lines (OHTLs) is of increasingly important considerations in several research areas due to their harmful effect on human health and environment. This paper computes the ground level magnetic field, under normal and abnormal conditions of Egyptian 500-kV single circuit transmission line, in three dimension (3-D) coordinates by using 3-D integration technique. Abnormal conditions include symmetric fault, un-symmetric faults, direct stroke, and indirect stroke on the OHTL. Where, ATP software is used to simulate the OHTL under all faulty and lightning conditions. Varying time magnetic fields under normal and abnormal conditions, at certain points that located at mid-span, tower height and right-of-way (ROW), are also computed that to indicate the worst case. DOI : http://dx.doi.org/10.11591/telkomnika.v12i5.5151

Study on statistical evaluation method of arrangements of interphase spacers for galloping of single conductor transmission lines

Study on statistical evaluation method of arrangements of interphase spacers for galloping of single conductor transmission lines

Classification of Faults on Transmission lines using EMTP and Wavelet Multiresolution Analysis

This paper presents a technique for classification of faults on single circuit transmission line using Wavelet Multiresolution Analysis.EMTP (Microtran) is used to perform simulations which generate time domain input signal on a 400KV, 300km transmission line fed from one end. Daubechies eight (D-8)wavelet transforms of the three phase currents on a transmission line fed from one end are used for fault analysis in this work. The summation of the 1 level output of MRA detail signals of current in each phase extracted from the original signals generated are employed in fault classification algorithm. Simulation results show that the proposed method is effective and simple and give accurate results irrespective of fault location, fault inception angle and fault impedance.

Analysis of Different 500kV HVAC Transmission Lines Lightning Shielding

The lightning shielding of different 500 kV HVAC-TL high voltage AC transmission lines was analyzed. The studied transmission lines were horizontal flat single circuit and double circuit transmission lines. The lightning attractive areas were drawn around power conductors and shielding wires. To draw the attractive areas of the high voltage transmission lines, transmission line power conductors, shielding wires and lightning leader were modeled. Different parameters were considered such as lightningslope, ground slope and wind on lightning attractive areas. From the calculated results, the power conductors voltages affected on attractive areas around power conductors and shielding wires. For negative lightning leader, the attractive area around the transmission line power conductor increased around power conductors stressed by positives voltage and decreased around power conductors stressed by negative voltage. In spite of this, the attractivearea of the transmission line shielding wire increasedaround the shielding wire above the power conductor stressed by the positive voltage and decreased around the shielding wire above the power conductor stressed by negative voltage. The attractive areas around power conductors and shielding wires were affected by the surrounding conditions, such as lightning leader slope, ground slope. The AC voltage of the transmission lines made the shielding areas changing with time.

Novel compact inverted U‐shaped directional coupler using parallel dual transmission lines technique

ABSTRACTA novel compact design of a 3‐dB inverted U‐shaped directional coupler using dual parallel transmission lines on double layer substrates is presented in this article. Dual parallel transmission lines technique is used as a replacement of the conventional single transmission line. Hence, a smaller size and wider bandwidth of directional coupler is successfully achieved. The proposed coupler is highly adaptable to various microwave applications for microwave circuitry such as the Butler Matrix (BM) beamforming network. The reduction in size gives better flexibility for the integrated structure of BM system. The proposed 2.45‐GHz coupler successfully obtaining size reduction up to 40% compared to the rectangular multilayer directional coupler. In addition, 25% bandwidth performance was achieved. Dimension and S‐parameter performance comparison has been made between the proposed coupler which use dual parallel transmission lines technique in multilayer structure and rectangular multilayer coupler. The measurement results are in good agreement with simulated ones in terms return loss, coupling, through and isolation. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:251–256, 2014