Transmission Line Interconnects Research Articles

P‐76: The Influence of Bending FFC Transmission Line on High‐Speed Signal Channels

Generally, display devices interconnect FFC transmission lines with circuits to form a transmission line network system to achieve data communication between Tcon and Driver. Due to the limitations of the external shape and internal space structure of the display device, the FFC transmission cable presents a curved shape from 0 to 180 degrees during the wiring process. Under the action of spatial electromagnetic fields, the display device will involve the field‐circuit hybrid problem of electromagnetic coupling of the FFC transmission line's bent line and circuit conduction interference, which will cause severe electromagnetic interference(EMI), resulting in deterioration of the high‐speed channel signal at the receiving end and even inability to correctly restore and decode the signal, thus causing signal distortion, which in turn leads to display image distortion or pixel loss.

The impacts of the transmission line length in an interconnected micro-grid on its performance and protection at different fault levels

Power systems, in recent years, have been experiencing a dynamic rise in the amount of power obtained from distributed renewable energy sources leading to the concept of microgrids to address the distributed power grid integration issues. Microgrids, a promising means of facilitating the green transformation of power systems, allow the union operation of distributed energy resources (DER) such as combined heat and power (CHP), renewables like photovoltaic (PV), wind and fuel cells (FC), energy storage systems, diesel generators, and controllable loads, either individually or in combination. The protection of DERs within microgrids can be considered as one of the main challenges associated with such phenomenon. Short and Long power transmission lines, in case of a fault, both have particular impacts on system parameters and may result into subsequent events threatening the microgrid and renewable generation units. On the other hand, The high penetration of microgrids not only can change the power flow within the power network, but it can also affect the fault current levels and may lead to their islanding in case of a fault. Before investing in microgrids, especially those in far places, this paper develops a tool to be used in investigating the influence of the interconnecting transmission line length as well as the type/severity of fault on the microgrid performance. The toolbox was developed using MATLAB/Simulink Toolbox. The developed tool was then validated on a case study microgrid and results show that the length of the interconnecting transmission line and the fault severity directly impact the microgrid performance (i.e. voltage and power deviations). In that case, interconnection or islanded mode is contingent upon the decision of the utility operator which also depends on the sensitivity of the equipment used in the microgrid.

Enhanced Control Designs to Abate Frequency Oscillations in Compensated Power System

The interconnection of transmission, distribution, and generation lines has established a structure for the power system that is intricate. Uncertainties in the active power flow are caused by changes in load and a growing dependence on renewable energy sources. The study presented in this paper employs several controlling strategies to reduce frequency variations in series-compensated two-area power systems. Future power systems will require the incorporation of flexible AC transmission system (FACTS) devices, since the necessity for compensation in the power system is unavoidable. Therefore, a static synchronous series compensator (SSSC) is installed in both areas of our study to make it realistic and futuristic. This makes it easier to comprehend how series compensation works in a load–frequency model. With the integration of electrical vehicles (EVs) and solar photovoltaic (PV) systems, several control strategies are presented to reduce the frequency oscillations in this power system. Particle swarm optimization (PSO) is used to obtain the best PI control. To improve results, this work also covers the design of fuzzy logic control. In addition, the adoption of neural network control architecture is proposed for even better outcomes. The outcomes clearly show how well the proposed control techniques succeeded.

An Improved Thru-Line De-Embedding Technique up to 80 GHz

With the rapid increase of high-speed communications, the frequency range of integrated circuits enters the field of millimeter wave, and the size of devices has become smaller and smaller. In the measurement of microwave devices, the probe cannot contact the device directly. The actual device under test (DUT) is surrounded by metal traces called leads, which provide the interface between the probing pads on the wafer and the DUT itself. The probes are pressed on the pads at both ends of the DUT. The parasitic effect of pads and transmission lines is significant at high frequency. The established technique such as Short-Open-Load-Thru (SOLT) and Line-Reflect-Reflect-Match (LRRM) move the reference plane up to the tip of the probes by means of Cascade Microtech impedance standard substrate (ISS). To obtain accurate parameters of DUT, a deembedding method must be implemented to eliminate the influence of pads and interconnect transmission lines.

Propagation of picosecond pulses on superconducting transmission line interconnects *

Interconnects are a major discriminator for superconducting digital technology, enabling energy-efficient data transfer and high-bandwidth heterogeneous integration. We report a method to simulate propagation of picosecond pulses in superconducting passive transmission lines (PTLs). A frequency-domain propagator model obtained from the Ansys high-frequency structure simulator (HFSS) field solver is incorporated in a Cadence Spectre circuit model, so that the particular PTL geometry can be simulated in the time-domain. The Mattis Bardeen complex conductivity of the superconductor is encoded in the HFSS field solver as a complex-conductivity insulator. Experimental and simulation results show that Nb 20 Ω microstrip PTLs with 200 nm interlayer dielectric thickness can support propagation of a single-flux-quantum pulse up to 7 mm and a double-flux-quantum pulse up to 28 mm.

Application of Sine–Cosine Optimization Algorithm for Minimization of Transmission Loss

On recent trends, the reactive power planning problem has received a considerable amount of attention for the allocation of reactive power resources, both static and dynamic such as switchable capacitors and/or reactors, as well as Var compensators, respectively. The reactive power has a significant impact on voltage profile, stability and transmission loss in power systems. In recent years, voltage instability is recognized as a major threat to system operation due to a shortage of reactive power in an interconnected transmission line. These voltage conditions could be analyzed and improved by proper coordination of reactive sources/sink. In this article, the minimization of transmission loss and operating cost is performed by using the sine cosine algorithm (SCA) and quasi-oppositional based sine cosine algorithm (QOSCA) technique for standard IEEE 14 and IEEE 30 and IEEE 57 bus test system of the connected power network. The proposed QOSCA reduces the transmission losses by 6.38% in IEEE 14, 4.56% in IEEE 30 and 12.77% in IEEE 57 bus system. The results obtained by QOSCA and SCA are compared with other popular techniques recently reported in recent state-of-literature. It is observed that QOSCA yields better results in terms of reducing transmission loss, operating costs, and improving the voltage profile of each bus.

Power Transfer Capability Recognition in Deregulated System under Line Outage Condition Using Power World Simulator

The major challenges in deregulated system are determination of available transfer capability on the interconnected transmission lines. Electricity industry deregulation is the required for creating a competitive market throughout the world, which instigate new technical issues to market participants and Power System Operators (PSO). Power transfer capability is a crucial parameter to decide the power flow in the lines for further transactions and the estimation of Transfer Capability decides the power transactions based on the safety and ability of the system. This parameter will decide if an interconnected network could be reliable for the transfer of bulk power between two different areas of the network without causing risk to system consistency. The Power Transfer Distribution Factor (PTDF) is the sensitivity index, which decides the transfer capability in the interconnected network under deregulated power systems. This experiment is conducted on IEEE-6 bus system using Power World Simulator to determine the transfer capability in deregulated system under line outage condition.

Structural Analysis of the US ITER ECH Transmission Line System

The electron cyclotron heating (ECH) and current drive system is one of the main plasma heating systems for ITER. It uses high-power microwave beams with the power deposition location steerable across the plasma cross section. Microwave power is conveyed via transmission lines (TLs) that run from the gyrotrons in the radio frequency building through the assembly hall and tokamak building to the ECH launchers within the tokamak vacuum vessel. The ECH system includes a vast array of interconnected TL waveguides, in-line components, and support structures. Finite element (FE) modeling provides an essential means of simulating the system, applying loads and determining deflections, rotations, forces, moments, and stresses in order to evaluate various structural and microwave transmission performance metrics. A representative FE model of the overall ECH TL system is developed in ANSYS®. This top-level model defines the centerline of the waveguide system. Waveguide segments are represented by line elements (beams and pipes) with equivalent section properties, and support structures are represented by boundary conditions. A systematic approach is used to model each ECH component with lumped masses and structurally equivalent stiffness matrices or ANSYS superelements. The top-level TL FE model is used to evaluate the various loads (thermal, vacuum, seismic, etc.) and operating scenarios. The top-level model directly calculates stresses in the straight aluminum waveguide segments. The model provides the forces and moments acting on the in-line components for detailed submodel assessments. Displacement results from the top-level analysis feed into a separate microwave performance model to help determine operational efficiency. All TL performance and thermal-structural requirements are met, as specified by the applicable codes and standards, and successfully documented in numerous technical reports and demonstrated at the final design review.

(Invited) Flexible and Stretchable Microwave Electronics

he development of microwave electronics has greatly advanced applications including communication, sensing, detection, and so on. The recently emerging markets like wearable devices, biomedical sensors, and foldable large-area microwave systems impose new requirements on microwave electronics, including flexibility, low weight, small size, and even stretchability. The unique mechanical properties of flexible and/or stretchable electronics renders them perfect candidates for applications like biomedical sensors and wearable devices, where the device needs to be attached or wrapped on nonplanar surfaces. Microwave electronics in flexible and/or stretchable form can substantially expand the application of these devices by eliminating lengthy connection wires and implementing modern wireless techniques. Therefore, flexible/stretchable electronics including fundamental components, functional circuits, and complete systems have attracted great interest from both academia and industry. The development of flexible microwave electronics has focused on fundamental flexible components like transistors and passive components in the past decades. As the heart of modern electronics, conventional semiconductor-based transistors have transformed into the flexible form through various mechanisms including substrate removal and exfoliation of the active layer on the surface. Silicon (Si), the most widely studied semiconductor material, has been extensively investigated for flexible microwave transistors. By employing technologies like strained channel and nanoimprinting, flexible Si thin-film transistors (TFTs) with excellent high-frequency performance were obtained. In addition, to extend the application of flexible transistors toward higher frequency and higher power, compound semiconductor-based flexible microwave transistors attracted increasing attention due to their superior material properties like high electron mobility, wide bandgap, and so on. The flexible GaInP/GaAs heterojunction bipolar transistor (HBT) and flexible AlGaN/GaN high electron mobility transistor (HEMT) have shown higher operating frequency than flexible Si TFTs. Besides superior high-frequency performance, flexible GaN HEMTs also show great potential for high-power flexible microwave electronics due to their wide bandgap and excellent thermal stability. The demonstrated flexible GaN HEMT can sustain a dissipation power of 0.5 W while achieving maximum oscillation frequency of 115 GHz. Besides the flexible transistors, flexible passive components operating at the GHz range, i.e. necessary parts of microwave circuits, are demonstrated as well. The operating frequency of inductors and capacitors have been pushed to beyond 10 GHz with optimization in device design. As the flexible microwave fundamental components continue to improve, flexible integrated circuits (ICs) consisting of fundamental components are being developed as well. Simple flexible circuits like switches and filters have been demonstrated by integrating Si or Ge diodes and passive components like inductors and capacitors. Flexible rectifiers, the critical component of wireless power transferring, are demonstrated using membrane GaAs Schottky diodes and flexible capacitors, which can harvest electromagnetic energy at WLAN band. Recently, a flexible power amplifier operating at 5.5 GHz with output power around 10 dBm has been reported. A reliable fabrication process flow has been developed to integrate small membrane GaN HEMT and flexible inductors and capacitors on polyimide thin film. Due to the excellent thermal reliability of GaN HEMT and heat spreader based on large coplanar copper ground plane, the amplifier can retain reliable operation with GaN membrane size as small as 0.5 mm by 0.5 mm. Compared to the rapid advancement of flexible microwave electronics, the development of stretchable microwave components is quite restricted due to the increased fabrication complexity and degraded device performance. The existing stretchable microwave components focus on passive components, especially the interconnect transmission lines. Due to the rigidness and fragility of semiconductor materials, stretchable microwave devices are typically made by connecting compact high-performance rigid/flexible semiconductor devices with stretchable interconnects. We have demonstrated a stretchable transmission line using a twisted structure, which can operate up to 50 GHz with minimized electromagnetic leakage. Recently, we successfully fabricated stretchable inductors operating at the GHz range. By connecting polyimide encapsulated compact spiral inductors with serpentine interconnects, the stretchable inductors inherit the high performance of a spiral inductor as well as the stretchability of serpentine lines. Although several key issues, including effective thermal management and enhanced reliability of the devices, require further research, flexible and stretchable microwave electronics have shown great promise in reshaping the existing electronics.

Adaptive Mho Distance Protection for Interconnected Transmission Lines Compensated with Thyristor Controlled Series Capacitor

This paper proposes an adaptive dynamic Mho distance relay based on a phase comparator scheme for protecting interconnected transmission networks compensated with a Thyristor Controlled Series Capacitor (TCSC). The proposed relay uses an impedance index factor to initiate the fault detection subroutine. The RMS of the positive sequence current of the faulted loop and the TCSC terminal current are compared for TCSC zone identification. A phase comparator for ground and phase distance elements is proposed, relying on the positive sequence voltage as a polarized memory quantity, while the operating and polarizing quantities are developed using estimated TCSC impedance to mitigate its negative impact. The proposed scheme is easy in implementation and independent on synchronized data transfer, as minimum communication requirements are needed. To evaluate the performance of the proposed scheme, extensive simulation studies were carried out on an IEEE9 bus system compensated with TCSC for different firing angles covering four modes of TCSC operations, different fault types, and fault locations. In addition, an IEEE-39 bus network, as a large interconnected system, is tested for validation purposes. The achieved results designate the precision of the proposed scheme. Moreover, the results indicate its effectiveness for fault resistance tolerance, close-in three phase faults, and stable power swing phenomenon compared with conventional relays.

Design of K-band modified hairpin filter with harmonic suppression using GaAs MMIC process

PurposeThe purpose of this paper is to present a K-band modified hairpin bandpass filter on a planar circuit with harmonic suppression and compact size.Design/methodology/approachThe inter-connect transmission lines of conventional hairpin filter are replayed by T-shaped open stub to achieve transmission zero for second harmonic. This filter is simulated and optimized by using electromagnetic simulation software and tested on-chip.FindingsThis proposed filter shows the return loss of better than −10dB, the insertion loss of better than 2 dB in pass-band and suppression of more than 40 dB at second harmonic.Originality/valueThe proposed filter can be designed on monolithic microwave integrated circuit, PCB or LTCC and it is useable for microwave and microwave and millimeter-wave systems.

Signal Balancing in Unbalanced Transmission Lines

Balanced lines operating as transmission line interconnects are subjected to differential-mode to common-mode conversion (and vice versa) in situations where symmetry imbalances (e.g., caused by line bends) are unavoidable. In this paper, a technique to compensate for such symmetry imbalances, providing pure differential-mode signals at the differential output port of the line, is presented. Such technique uses a rat-race balun (to generate the differential-mode signal) with the isolated port conveniently loaded, and it is based on the modification of the characteristic impedance of one of the unbalanced lines. A detailed analysis that justifies this compensation technique (valid for any arbitrary four-port network) and provides the design equations is presented. The approach is validated through simulation and experiment, by demonstrating that common-mode signals are not transmitted to the differential output port of a bended (i.e., unbalanced) line pair.

Distinguishing Dielectric Loss From Superconductor Loss Using Flexible Thin-Film Superconducting Resonator Structures

Flexible interconnects with superconducting (SC) traces and polyimide dielectric can provide low signal loss and low thermal conductivity at cryogenic temperatures, and are expected to find use in densely integrated cryogenic electronics systems. The ultra-low loss of SC interconnects at microwave frequencies can be accurately characterized through the use of weakly coupled SC resonators. The high-quality factor resonators provide sensitive measurements of the aggregate loss properties of the conductor and dielectric, as functions of frequency, temperature, and signal power. In this work, resonators with different linewidths were fabricated and tested to study how the linewidth impacts the overall internal resonator loss, in order to better characterize and separate the individual loss components (i.e., dielectric loss vs. conductor loss). The results of this work are important for understanding loss and transmission properties of similarly designed and fabricated transmission line interconnects.

False Data Injection Attacks With Limited Susceptance Information and New Countermeasures in Smart Grid

In this paper, we consider false data injection (FDI) attacks with limited information of transmission-line susceptances and new countermeasures in smart grids. First, we prove that the adversary could launch FDI attacks to modify the state variable on a bus or superbus only if he/she knows the susceptance of every transmission line that is incident to that bus or superbus. Based on this observation, we provide a new countermeasure against FDI attacks, i.e., to make the susceptances of n-1 interconnected transmission lines that cover all buses unknown to the adversary (e.g., by proactively perturbing transmission-line susceptances through distributed flexible AC transmission system (D-FACTS) devices), where n is the total number of buses. This new countermeasure can work alone or in conjunction with traditional ones to reduce the number of meter measurements/state variables that are to be secured against FDI attacks. The implementation of FDI attacks with limited susceptance information and the effectiveness of new countermeasures are demonstrated by using an illustrative 4-bus power system and the IEEE 9-bus, 14-bus, 30-bus, 118-bus, and 300-bus test power systems.

Performance Improvement of Various Types of Induction-based Wind Farms Using Center-node Unified Power Flow Controller

In this paper, we propose the use of center-node unified power flow controller (C-UPFC) for improving the performance of different types of wind farms and mitigating their negative impacts on the grid. C-UPFC is considered one of the modernist members on Flexible AC Transmission System (FACTS). C-stocktickerUPFC has the ability to control several system parameters; the active and reactive power at both ends of the interconnected transmission line and the voltage at the midpoint. Three different induction-based wind farms are considered; 1) Squirrel Cage Induction Generator (SCIG), 2) Doubly Fed Induction Generator (DFIG), and 3) a combination of SCIG and DFIG turbines, i.e., Combined Wind Farm (CWF). C-stocktickerUPFC is comprehensively modelled for the first time in MATLAB Simulink, then the performance of the three wind farms is assessed with and without this device during three phase faults. Probabilistic voltage stability index (Probabilistic VSI) is used to measure the stability of the studied systems. In addition, the performance of three wind farms integrated with C-UPFC is compared with their performance when they integrated with Static synchronous compensators (STATCOM). The results show that C-UPFC has the ability to enhance the performance of wind farms during the three phase fault. C-UPFC is capable to remain the connection between SCIG wind farm and the interconnected grid during the fault. The voltage of CWF is greatly enhanced in the case of using C-UPFC. C-UPFC also improves the output powers of DFIG and CWF, especially after fault clearance.

A Novel Dual-Sided Fly-By Topology for 1–8 DDR With Optimized Signal Integrity by EBG Design

A novel dual-sided fly-by topology is proposed for one controller to multiple memory systems by choosing interconnected transmission line sections of alternate impedance and length. After suitable big data analysis of automatic simulation, peak distortion analysis for eye height, followed by artificial neural network optimization, the best design guideline can be deduced, which is found to be consistent to the electromagnetic bandgap (EBG) theory. The topology may greatly enhance the eye height by 20%–100% while the total length is reduced by half, compared with the conventional fly-by topology. The general design method, relevant simulation, and analysis from EBG are also provided. Measurement has been performed to validate the new design, demonstrating 53% improvement in eye height over the conventional one.

Interconnection of Transmission Lines with Different Imbalance Factors and Mode Conversion

Interconnection of Transmission Lines with Different Imbalance Factors and Mode Conversion

Origin and mitigation of increased electric fields at high voltage transmission line conductors

In this paper analysis of the origin and mitigation measures of increased electric field at high voltage transmission lines in the electric power system of Bosnia and Herzegovina is given. In the analyzed period (2010–2017) in the electric power system of Bosnia and Herzegovina increased values of power frequency voltages was registered. The performed analysis shows that the increased voltages in the 400 kV nodes of the electric power system of Bosnia and Herzegovina are occurring during the night, mainly in the minimum consumption regimes. Increased voltages can occur throughout the year, but are most frequent during the spring and summer months. In the coming years, four 400 kV interconnection transmission lines to Serbia and Croatia will be built. Increasing of the voltage value causes the formation of the corona as well as energy losses. Taking into account the values of the energy losses due to the corona, it is important to determine the values of the electric field on the surface of the conductors and their immediate vicinity as well as the value of the corona onset electric field in order to know their values in the electric power system and to explore ways to mitigation them from the aspect of maintenance and management costs.

Interconnected Multi-1-D FADI- and FLOD-FDTD Methods for Transmission Lines With Interjunctions

This paper presents the interconnected multi-1-D (IM1-D) fundamental alternating-direction-implicit finite-difference time-domain (FADI-FDTD) and fundamental locally 1-D finite-difference time-domain (FLOD-FDTD) methods for transmission lines with interjunctions. The proposed methods are unconditionally stable and capable of treating multiple main transmission lines and stubs interconnected at various interjunctions using time step larger than Courant–Friedrichs–Lewy limit. Fundamental scheme-based IM1-D FADI- and FLOD-FDTD methods are derived to enhance the efficiency with matrix-operator-free right-hand sides. The methods involve one-step update procedure optimized for simulation of main transmission lines and stubs on mobile device. Using proper treatments at the interjunctions for various interconnection conditions, the electromagnetic fields in all interconnected main transmission lines and stubs can be updated cooperatively and efficiently to solve practical problems. A microstrip line loaded with stubs and a branch-line coupler are simulated to show the accuracy and efficiency of the proposed methods. To extend the applicability for handling the couplings between two transmission lines via gaps, a microstrip circuit with gaps is simulated using the proposed methods incorporated with equivalent circuit models involving capacitances. Real-time simulations of these numerical examples provide much intuitional insight for one to observe the electromagnetic waves propagation in time domain on computer or mobile device.

100 Gbps (4 × 25 Gbps) Optical Receiver Module Packaged in Chip-on-Board Based on Germanium Photodetector

100 Gbps (4 × 25 Gbps) optical receiver (Rx) module is demonstrated using Germanium (Ge) photodetector (PD) which is fabricated through Silicon-photonics process using 750 ohm-cm of high-resistivity silicon oxide insulator (SOI) wafer. Trans-impedance amplifier (TIA) and Ge PD are packaged with chip-on-board (COB) manner on a printed circuit board (PCB). High speed PCB for the assembly of both electronic and photonic devices in COB package is precisely designed from the material selection to the device footprint layout and transmission line design. The layout on PCB is optimized using high frequency simulation tool of HFSS to minimize RF loss happening in the transmission line and electrical interconnection points of bond wires. Electrical-optical (EO) S-parameter measurement for the Ge PD shows 22 GHz of transmittance (S21) 3dB bandwidth. Photocurrents of the photodetector induced by the optical input power are analyzed for signal integrity both TIA ON and OFF states. Photocurrent changes by the misalignment of the lensed optical fiber coupled to the edge coupler of the Ge PD shows that 3dB misalignment tolerances are 5.5 µm in the longitudinal and around +/-1 µm in the lateral directions. This COB packaging technique of optical Rx module can be applied for the integration and assembly of the optical module of higher data rate of 100 Gbps and beyond.