Connected Transmission Lines Research Articles

Fault Location Method for STATCOM Connected Transmission Lines Using CCM

Determining the fault location using conventional impedance based distance relay in the presence of FACTS controllers is a challenging task in a transmission line. A new distance protection method is developed to locate the fault in a transmission line compensated with STATCOM with simple calculations. The proposed protection method considers the STATCOM injected/absorbed current to correct the fault loop apparent impedance and accordingly calculates the actual distance to the fault location. The comprehensive equations needed for apparent impedance calculation are also outlined and the performance is evaluated and tested with a typical 400 KV transmission system for different fault types and locations using MATLAB/SIMULINK software. The evaluation results indicate that the new protection method effectively estimates the exact fault location by mitigating the impact of STATCOM on distance relay performance with error less than 0.3%.

Connecting wearable textile transmission lines: all‐textile fabrication solutions and design techniques

A new method for connecting transmission lines is presented without using rigid connectors in order to implement a fully textile interconnecting system appropriate for signal transmission in wearable applications. This method is applied to textile striplines and named ‘complementary overlap’. The proposed method is examined from 1 to 6 GHz covering the frequency bands of the target applications: ISM (WLAN, Bluetooth, ZigBee etc.) and L-band (GPS).

An unequal Gysel power divider based on circuit transformation

ABSTRACTThis article presents an unequal Gysel power divider (UGPD) based on circuit transformation, which is converted from a Π‐ to a T‐type circuit. The Π‐type circuit of a conventional unequal Gysel divider consists of two different value resistors and its connection transmission line. In the proposed T‐type circuit, the dummy transmission line and the other transmission line with shunt resistor at center position is connected in parallel. Theoretical analysis was performed to derive the design equations for the proposed circuit conversion. For the validation of the circuit transformation, the UGPD using a T‐type circuit at the center frequency of 2 GHz was fabricated and measured. The measured characteristics agreed well with the simulation results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1529–1531, 2015

A novel distributed unit transient protection algorithm using support vector machines

Based on fault initial angle and transition resistance, a novel ultra-high-speed distributed unit transient protection algorithm is established to protect a busbar and a connected transmission line simultaneously for EHV (extra high voltage) substation through analysing the direction and instantaneous amplitude of the fault-generated high-frequency transient current by utilizing SVM (support vector machine). The fault direction was first judged during the process, and then the fault location was determined by employing different trained SVMs. In addition, the fault initial angle and transition resistance are imported into the input vector of SVMs, through which their adverse effects on the protection performance can be significantly eliminated. Moreover, the proposed algorithm extracts the fault transient information just relying on one transmission line connected to the busbar rather than overall feeders, thus simplifying the process while ensuring high reliability. Further, only typical fault samples instead of all samples are needed during the SVM training procedure, which makes it quite appropriate for practical projects. According to massive simulation results on a typical EHV transmission system on ATPDraw platform, the proposed algorithm can precisely determine whether the fault occurs within the protected busbar or on the protected line or outside the protected area.

Development of Adaptive Distance Relay for STATCOM Connected Transmission Line with Wavelet Transform and ANN

A new scheme to enhance the solution of the problems associated with Transmission line protection with Statcom connected is presentedin this paper.Static Synchronous Compensator (STATCOM) is a shunt type FACTS device connected at the midpoint of the transmission line to maintain the voltage atdesired level by injecting/absorbing the reactive power. This connection affects the performance of distance protection relay during line faults. Thefault detectionis carried out byusingenergy of the detail coefficients of the phase signals and artificial neutral network algorithm used for fault distance location for all thetypes of faults for transmission line. For each type of fault separate neural network is prepared for finding out the fault location.

Comment on sharp‐rejection and ultra‐wide bandstop filter with five transmission zeros frequencies

In this letter, explicit transmission zero conditions, for the ultra-wide bandstop filter (BSF) with five transmission zeros, are derived using even-odd mode, analysis. The BSF topology is obtained by folding the two connecting transmission lines in a conventional optimum BSF to compose a stub-loaded coupled-line section and using λ g/2 end open-stubs. A necessary and sufficient condition is explored for the crucial coupled-line section to produce three transmission zeros. Further, it is shown that the same five zeros BSF stopband bandwidth and rejection level performance is obtained with compact three zeros BSF (without λ g/2 open-stubs) with improved passband flatness and return loss.

A 15–40-GHz Frequency Reconfigurable RF MEMS Phase Shifter

This paper presents a novel frequency reconfigurable phase shifter using the RF microelectromechanical systems (MEMS) technology. The phase shifter is based on the triple-stub circuit topology composed of three stubs that are connected by two transmission lines that are all implemented as distributed MEMS transmission lines. The insertion phase of the circuit is controlled by changing the electrical lengths of the stubs and the connecting transmission lines, while having ideally zero reflection coefficient at all times. The phase shifter has theoretically no specific limits on the frequency; in other words, it can be reconfigured to work at any frequency between 15-40 GHz, with adjustable phase steps, while providing a constant time delay within a 2%-3% instantaneous bandwidth around any selected center frequency in the above-mentioned band. The phase shifter is fabricated monolithically using a surface micromachining process on a quartz substrate and occupies 10.8 mm × 5.9 mm. Measurement results show that the phase shifter has average phase error of 1.6 °, 3.7 °, and 4.7 °, average insertion loss of 3.1, 5, and 8.2 dB and average return loss of 19.3, 15.8, and 13.7 dB at 15, 30, and 40 GHz, respectively. To the best of our knowledge, this paper demonstrates the first phase shifter in the literature that can work at any given frequency in a targeted band with adjustable phase steps.

Design of ultra‐wideband bandstop filter using defected ground structure

A simple wideband bandstop filter which yields equal ripples in the stopband is described. The filter comprises only two resonators and a connecting transmission line. Ultra-wide stopband characteristic is achieved by realising three transmission zeros near the passband edges. Stopband rejection depth and bandwidth can be controlled by impedances of the configuration. The defected ground structure is chosen to realise the high impedance line. To validate the proposed topology, a compact microstrip bandstop filter centred at 1.5 GHz with a measured 20 dB rejection bandwidth of about 139% is fabricated.

병렬 연결된 전송선로를 이용한 비대칭 전력 분배기

본 논문에서는 병렬 연결된 전송선로를 이용하여 고 비율 비대칭 전력 분배기를 설계하였다. 병렬 연결된 전송선로는 마이크로스트립 기술로 구현하기 어려운 낮은 임피던스의 전송선로를 높은 임피던스 전송선로로 구현하는 방법이다. 비율 비대칭 분배기 구현 시 사용되는 낮은 임피던스를 구현하기 위하여 병렬 연결된 전송선로를 이용함으로서 구현을 쉽게 할 수 있었다. 이러한 설계방법의 타당성을 보이기 위해서 중심 주파수 1 GHz에서 10:1 비율의 비대칭 전력 분배기를 제작하였고, 이것의 특성은 시뮬레이션과 거의 동일함을 확인하였다. In this paper, a high dividing ratio unequal power divider using parallel connection transmission line is presented. Because a very low impedance transmission line can't implement a microstrip technology, this can fabricate a parallel connection transmission line with high impedance. When we design a high dividing ratio divider, we need the very low impedance line. The parallel connection transmission line could be implemented to obtain a low impedance line characteristic. To validity this approach, we are implemented a 10:1 unequal divider at center frequency 1 GHz. The performances of power divider agree with simulation results.

An ANN-Based Approach for Lightning-Caused VFT Detection in GIS

This paper introduces an artificial neural network (ANN) approach for the detection and identification of lightning-caused very fast transient (VFT) in gas insulated substation (GIS). VFT in GIS can be due to faults, lightning and switching operations. VFT in GIS has to be located and classified as soon as possible to start the processes of reconfiguration and restoration of the normal power supply. A practical case study is investigated in Talkha 220-kV GIS which represents a critical generation point in the Egyptian Electric Power Network. The layout of the Talkha 220-kV GIS is discussed and modeled using ATP/EMTP. The ANN-based approach is built and trained. Finally, the proposed approach is tested using bolt ground faults, high impedance faults, and lightning on the connected transmission lines. The results ensure the success of the proposed approach to classify and discriminate the faults and the lightning-caused VFT.

Reduction of the dependence of the frequency of a passive resonant surface acoustic wave sensor with magnetic coupling on the angle of rotation of the shaft

The effect of connecting a rotating ring joint on the frequency of a passive contactless surface acoustic wave resonant sensor with the combined use of a model based on connected transmission lines and its equivalent electric circuit with lumped elements is analyzed. The considerable reduction in the dependence of the frequency of the sensor on the angle of rotation of the shaft and the reduction in the error of measurements carried out on the shaft when both rotating ring joints are completely symmetrically connected are demonstrated.

Enhanced Microwave Multiplexing Network

A new approach for designing a microwave multiplexing network is presented in order to improve channel performance. Through design and optimization of the connecting transmission line structure, the new approach ensures that an extra pole is formed in the passband of each channel. The channel filter order is therefore increased by one without additional resonators. Significant improvement in the performance of the multiplexer is achieved without the penalty of increased size or weight of the hardware, which is extremely important for applications in communication satellite. Simulation and measurement results are used to demonstrate the feasibility of such enhanced microwave multiplexing networks.

A NEW WIDE-STOPBAND LOW-PASS FILTER WITH GENERALIZED COUPLED-LINE CIRCUIT AND ANALYTICAL THEORY

A generalized coupled-line circuit is introduced to construct a wide-stopband low-pass fllter in this paper. This circuit conflguration includes two-section coupled lines and a connected transmission-line stub. Due to the symmetry of this proposed structure, closed-form equations for scattering parameters are investigated. The transmission zeros and poles locations for difierent circuit parameters are discussed, and the corresponding design curves are given. For theoretical veriflcations, four typical numerical examples are designed, calculated and illustrated. Furthermore, two single-stage low-pass fllters (LPF 1 and LPF 2) with the 1-dB cutofi frequencies of 0.72GHz and 1.45GHz are fabricated and measured. The implemented LPF 2 has 19-dB stopband rejection in the range of 2.05 to 6.36GHz. Finally, two LPF cells (LPF 1 and LPF 2) and an additional connected transmission line are used to construct a new two-stage low-pass fllter (LPF 3) with extended stopband. The measured 16-dB stopband of LPF 3 is up to 7.5GHz while the 1-dB passband range is from DC to 0.67 GHz. The advantages of this proposed low-pass fllter are avoiding any lumped elements and compact layout structure.

Double resonant stub bandstop filter with pseudo-elliptic response

A simple wideband bandstop filter that yields equal ripples in both the pass- and the stopbands is described. The filter comprises only two resonant stubs and a connecting transmission line and has a transmission response almost identical to that of a third-order elliptic function filter. The practical bandwidth is limited to 130–160%.

Compact Multi-harmonic Suppression LTCC Bandpass Filter Using Parallel Short-ended Coupled-line Structure

This paper presents a novel simple filter design method based on a parallel short-ended coupled-line structure with capacitive loading for size reduction and ultra-broad rejection of spurious passbands. In addition, the introduction of a cross-coupling capacitor into the miniaturized coupled-line can create a transmission zero at the second harmonic frequency for better frequency selectivity and attenuation level. The aperture compensation technique is also applied to achieve a strong coupling in the coupled-line section. The influence of using the connecting transmission line to cascade two identical one-stage filters is studied for the first time. Specifically, such a two-stage bandpass filter operating at 2.3 GHz with a fractional bandwidth of 10% was designed and realized with low-temperature co-fired ceramic technology for application in base stations that need high power handling capability. It achieved attenuation in excess of −40 dB up to 4f0 and low insertion loss of −1.2 dB with the size of 10 mm × 7 mm × 2.2 mm. The measured and simulated results showed good agreement.

Numerical studies of interchip pulse transmission for complex RSFQ systems

As the complexity of superconducting digital systems increases, the necessity of a careful design of interconnecting structures becomes more and more evident. Especially in the communication between chips, discontinuities are inevitable. Deriving a high frequency characterization of critical regions is therefore a crucial step for a design-oriented microwave modeling. We employed the finite-difference time-domain technique based on the discretization of Maxwell's equations for the numerical analysis of typical interconnect components, e.g. flip chip connection pads, vias, and transmission line discontinuities. The peculiar properties of superconductors are taken into account by incorporation of the London equations and the two-fluid model into the numerical scheme. Computer simulations have been carried out for various arrangements. Their results show in the time-domain how the shape of a rapid single flux quantum (RSFQ) pulse is affected by passing a discontinuity in the interchip signal path. Furthermore, frequency domain characterizations are obtained in terms of scattering parameters providing information about the bandwidth of the structure under investigation.

95/04794 Fundamental engineering problems and opportunities in operating powet transmission grids of the future

Based on fault initial angle and transition resistance, a novel ultra-high-speed distributed unit transient protection algorithm is established to protect a busbar and a connected transmission line simultaneously for EHV (extra high voltage) substation through analysing the direction and instantaneous amplitude of the fault-generated high-frequency transient current by utilizing SVM (support vector machine). The fault direction was first judged during the process, and then the fault location was determined by employing different trained SVMs. In addition, the fault initial angle and transition resistance are imported into the input vector of SVMs, through which their adverse effects on the protection performance can be significantly eliminated. Moreover, the proposed algorithm extracts the fault transient information just relying on one transmission line connected to the busbar rather than overall feeders, thus simplifying the process while ensuring high reliability. Further, only typical fault samples instead of all samples are needed during the SVM training procedure, which makes it quite appropriate for practical projects. According to massive simulation results on a typical EHV transmission system on ATPDraw platform, the proposed algorithm can precisely determine whether the fault occurs within the protected busbar or on the protected line or outside the protected area.

Transmission line routing for reduced external field disturbance

When immersed in a disturbing electromagnetic field, electronic systems are subject to interference due to the energy injected by the external field into the system through the electronic units and, especially, through the transmission lines connecting units one another. The issue of reducing the unwanted energy injection through connecting transmission lines is addressed in this contribution from the point of view of the routing, i.e. of the disposition of the connecting lines that minimizes the injection. The problem is formulated as an optimization problem, dealt with by the simulated annealing minimization technique combined with an efficient way of computing the field coupling to the lines. Results are reported for various cases, and the relation between the characteristics of the interfering field and the efficiency of the reduction is discussed.

Superdirective cascaded dipole array

With a view to realizing a superdirective antenna, an endfire array consisting of parallel dipole elements is analyzed. As a feeding method, a cascaded connection of all elements by transmission lines is proposed. A possibility of a superdirectivity and a basic design guideline are found for the case where an element spacing and the characteristic impedance of the connecting transmission lines are set arbitrarily. As the element spacing is reduced, the antenna becomes smaller and the gain increases, although the feeding becomes more difficult. Hence, the case of a finite-element spacing is discussed. First, it is demonstrated that the maximum gain as a superdirective antenna is obtained by adjustment of the element lengths and the lengths of the connecting transmission line. Further, it is shown that the optimum element length for the maximum gain is near the half-wavelength even if all elements have an identical length for ease of design and that such a structure works as a superdirective antenna. Based on the findings, a quarter-wavelength spacing, three-element array is designed. The validity of the present method is demonstrated since the experimental results for the input impedance, gain, and directivity agree well with the theoretical prediction.

Electromagnetic Transients in a Line-Transformer Cascade by a Numerical Laplace Transform Technique

The purpose of this work is to present a method for studying electromagnetic transients appearing in a power network consisting of a long transmission line and a transformer connected in cascade. An exact equivalent circuit representation of the system is developed using distributed element analysis in the s-domain. The proposed model assumes distributed inductances and self and mutual capacitances within the transformer windings. In addition, the new model can easily account for various connections of the transformer neutral. The line, which can be of any length, is represented by a single exact two-port network which is derived from distributed parameter theory. The new model yields closed form expressions in the s-domain for the transient potential distributions along the turns of the transformer winding as well as the connecting transmission line.