Length Of Transmission Line Research Articles

Network topology planning method for interconnecting large-scale renewable generators considering dynamic stability limitations

It is well-known that the connection of renewable generators (RGs) can result in stability issues. However, existing network topology planning methods primarily focus on economic factors and static safety constraints, often neglecting dynamic stability considerations. The aim of this study is to avoid the risk of oscillations at the planning stage, rather than addressing them through damping control after their occurrence. First, an index is proposed for numerically evaluating the impact of different network topologies on the stability of connecting RGs, concluding that parallel connection is the most stable among various topologies. Then, in scenarios involving multiple collection regions of RGs, a method is proposed to select the connection locations of RGs. This indicates that the distribution of wind generators should consider the transmission line length of collection nodes, rather than connecting all wind generators to one of them. Finally, the network topology planning steps from a dynamic stability perspective are summarized. It is meaningful to improve the stability of a power system connected by large-scale RGs without the need for additional damping control. Two case studies are conducted to validate the accuracy of the analyzed results, but in the future, more applicable examinations will be conducted.

Research on a transmission line defect identification method based on voiceprint recognition

Abstract With the continuous development and improvement of China’s power system, the length and coverage of transmission lines are getting larger and larger, making it inevitable that transmission lines will pass through areas with harsh environments and complex geographical environments. If defects are not discovered and handled properly, over time, serious losses will be caused. Traditional manual inspections can no longer meet actual requirements due to low efficiency. This paper proposes a transmission line defect identification method based on voiceprint recognition. First, the sound signal collected by the sensor is divided into frames and windowed for preprocessing. Then, feature extraction is performed based on the Mel frequency cepstral coefficient. Finally, the extracted vector is used to train the nearest neighbor classifier, and the trained classifier can identify defects in transmission lines.

Investigation of grid-forming and grid-following converter multi-machine interactions under different control architectures

The proliferation of converter-interfaced generation necessitates the investigation of novel small-signal multi-machine interactions. The flexibility and lack of standardisation of converter control approaches results in a plethora of potential implementations, bringing different dynamics that can interact with each other and existing elements of the power system. This paper performs a small-signal analysis of power systems with the inclusion of grid-forming and grid-following converters for varying combinations of common control architectures, in terms of cascaded control loops, within the literature. Investigations are performed for a two-machine system and the WSCC 9-bus (three-machine) system. As well as interaction identification and characterisation, the impact of varying transmission line lengths, system loading, and generation dispatch are investigated.

Compact Ultra-Wideband Wilkinson Power Divider in Parallel Stripline with Modified Isolation Branches.

An efficient design method for a compact and ultra-wideband multi-stage Wilkinson power divider in a parallel stripline (PSL) is proposed. To enhance the frequency bandwidth of the proposed power divider while reducing its size, the isolation branch is modified; that is, two capacitors are connected to both sides of a resistor at each isolation branch. For an efficient design process, the PSL power divider is equivalently represented by two microstrip power dividers, and the design equations are derived. Based on the design equations, an in-house algorithm is utilized to optimally determine the design parameters, including the line impedance, resistance, and capacitance of each stage. For example, a three-stage PSL power divider is designed with three λ/4 transmission lines at a base frequency of 5 GHz. To verify the accuracy of the design procedure, 3D EM simulations and measurements are performed, and the results show good agreement. Compared with the conventional three-stage Wilkinson power divider, the proposed PSL power divider achieves a wider frequency bandwidth of 1.16 to 6.51 GHz (139.5%) and a 23% shorter transmission line length of 207°, while exhibiting an insertion loss of 0.7 to 1.4 dB.

Design of Series-Fed Circularly Polarized Beam-Tilted Antenna for Microwave Power Transmission in UAV Application

In response to the increasing deployment of unmanned aerial vehicles (UAVs) across various sectors, the demand for efficient microwave power transmission (MPT) systems for UAVs has become paramount. This study introduces series-fed circularly polarized (CP) and passively beam-tilted patch array antennas designed to enhance MPT in UAV applications, with the intention of addressing the needs related to extending flight times and improving operational efficiency. The radiating element of the proposed antennas employs the conventional model of the patch with truncated corners for CP operation, with transmission line lengths optimized for beam tilt to ensure precise energy transfer. Additionally, an open stub is integrated into the broadside series-fed antenna to improve impedance matching, which is crucial for maintaining signal integrity. The proposed design achieves right-hand circular polarization (RHCP) with an axial ratio (AR) below 3 dB across the operating band, indicative of its effectiveness in diverse UAV operational contexts. Prototypes of each proposed antenna were fabricated and measured according to the beam tilting angle. The measured RHCP realized gains of the proposed antennas are 14.59, 13.09, 13.07, and 10.71 dBic at the tilted angles of 0°, 15°, 30°, and 45°, respectively, at 5.84 GHz.

An impedance transformer for UHF RFID and WiFi cross‐technology communication‐based tourism crowd counting

AbstractThis letter proposes a novel cross‐shaped structure‐based parallel coupled line transformer and its application to tag antenna for 920‐MHz radio frequency identification (RFID) and 5‐GHz WiFi Cross‐Technology Communication (CTC). This transformer can be tuned by some lumped capacitors and the equivalent transmission line length for high order harmonic matching. The WiFi is applicable for tourism crowd counting and its counting accuracy may be increased with an additional number of the virtual WiFi Access Points contributed by 5‐GHz resonance of said tags attached with touristic metallic objects. To study the 5‐GHz resonance of these tags the tag antenna is a square patch with a rectangular slot built with 3D acrylonitrile butadiene styrene printing material. The working frequency of the antenna is around 920 MHz, which can achieve a gain of 5.4 dBi and there is also a resonance at 5.6 GHz with a gain of −6.7 dBi. When the capacitor is tuned, the 5‐GHz band of WiFi is varied from 5.2 to 5.6 GHz applicable to emerging WiFi 5 and 6 CTC applications. It is anticipated that the prototype tag provides a flexible tourism crowd counting solution using CTC in the future.

A Telegrapher’s equations-based implicit finite difference solution for fault location with current transformer saturation

This paper introduces a fault location method based on time analysis, utilizing synchronized data collected from both ends of the faulted line. The data is obtained either from Common Format for Transient Data Exchange (COMTRADE) files or Sampled Measured Value (SMV) of the IEC-61850 protocol. The method proposed in this study employs the implicit finite difference solution to the Telegrapher’s equations. In certain fault scenarios, such as when one or both transformers experience saturation, a narrow time window of data can be utilized to accurately pinpoint the fault location. The implicit solution method is unconditionally stable and therefore decouples the choice of the line discretization step from the sampling time interval, which is commonly required to maintain numerical stability of the explicit strategies for fault location. Furthermore, the numerical stability of the implicit process allows for devising a systematic search procedure that improves the accuracy of the calculated fault location, regardless of the transmission line length. By conducting numerical comparisons with an explicit time-domain fault locator and recent frequency-domain algorithms, the superiority of the proposed approach becomes evident. The results highlight the significant improvements achieved through the utilization of this method. Specifically, the results demonstrate that Telegrapher’s Equations implicit finite difference solution maintains accuracy under current transformer saturation, as it can locate the fault using data from a brief interval where the current transformer is not saturated.

Using sampled values in line differential protection – Analyzing the scheme feasibility and protection performance under communication stress scenarios

Line differential protection features great selectivity to isolate equipment under fault conditions. However, this technique has been limited by factors such as transmission line length, communication network delay, use of proprietary protocols, or vulnerability to network failures. The IEC 61850 standard enables the implementation of digital substations, which have proven to be a good option for improving the reliability and efficiency of the electrical system. In this sense, we propose a new scheme for differential protection in transmission lines using SV messages by the IEC 61850 standard. In addition, we carry out a feasibility for differential protection in two 500 kV transmission lines of the Brazilian interconnected system using the Aspen Oneliner software. We evaluate the communication performance of the proposal in a testbed with two SEL 421–7 protection relays capable of sending and receiving SV messages, an Omicron CMC 356 test case, a PTP signal distributor device SEL-2488, an SEL-9524/GNSS antenna, switches for proper formation of communication buses, and hardware to emulate the length of the transmission line communication channel, generate concurrent traffic injection, and also induce package loss scenarios for the SV messages. The results are promising and indicate the viability of the proposal.© 2017 Elsevier Inc. All rights reserved.

A compact and reconfigurable C-band DGS-based power divider using RF MEMS capacitive switch

This article presents a reconfigurable and compact power divider design that utilizes a combination of defect structures in the ground plane (DGS) and capacitance loading using a unique RF MEMS switch on the sapphire substrate. The combination of these two techniques results in a reduced-size reconfigurable power divider, wherein the length of the quarter-wavelength transmission line is reduced to λ/16 from λ/4, and the higher-order harmonics are suppressed up to 40 GHz. The RF MEMS capacitive switch is designed, and its DC characteristics are simulated in coventorware. The RF characteristics of the designed power divider are simulated in Ansys HFSS 19.2. The power divider utilizing RF MEMS technology has been fabricated through surface micromachining, requiring only four masks for fabrication. According to measurement findings, insertion loss and return loss are 3.57 dB and 24.6 dB (at 4.4 GHz) and 3.82 dB and 22.06 dB (at 5.4 GHz) when the switch is on and off, respectively. The total area of the design is 3.1 mm2 (21.3% of the conventional power divider). The proposed design can suppress harmonics up to the 8th order by 10 dB. These features render it a viable option for employment in Radio Frequency Integrated Circuits (RFICs).

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.

Frequency Stability Analysis of a Dynamic Wind Park in an Integrated Power Grid

In spite of rapidly growing wind power capacities, wind power still only accounted for a small fraction of the electric power supply in the last years. Therefore, research in the area of wind power was mostly focused on the wind generators and wind parks themselves, aiming to maximize their efficiency and stability. But as the weight of wind power grows, their influence on power systems cannot be neglected anymore. That is why recent research like [1], [2] or [3] studies the effects that wind parks have on the dynamic power grids they are connected to. Continuing in this direction, we implement a simulation model of a power grid including a wind park and study its dynamic behavior with varying wind speed. The influence of certain parameters like transmission line length, rated power of the wind park or control depth on the frequency stability in the power system are studied and analyzed. Furthermore, a control scheme to integrate the wind park into the grid frequency control is implemented.

Optimization of losses by switching to higher voltage in distribution networks

The article considers the basis of scientific research in the field of electric power industry the issues of transition to 20 kV voltage in the distribution power grids of Uzbekistan. The main advantages of this method are analysed, as well as the factors affecting power and energy losses in electrical systems and networks. The paper presents a schematic diagram of an electric network section, on which a comparative calculation and analysis of voltage, energy and power losses in 6/10/20 kV networks is carried out. Special attention is paid to the peculiarities of calculation of these parameters, as well as the basic expressions for their calculation and the resulting graphical relationships. From the analysis it can be concluded that it is reasonable to use 20 kV voltage in distribution networks. It allows to reduce power and energy losses, which is an important factor in the efficient operation of electric power systems, to increase line capacity and service range. However, when selecting the optimal voltage for certain conditions, it is necessary to take into account a number of factors, such as the length of transmission lines, the type of wires and transformers used, and the load level of the network.

A Singly Curved Conformal Phased Array with Integrated Particles-Based CRLH Phase Shifters

In this paper, a four unit cell micron-sized magnetic particles embedded composite right/left-handed (CRLH) transmission line metamaterial phase shifter is proposed. The variable phases are achieved by activating the micron-sized magnetic particles along the length of stub transmission lines of the CRLH transmission line structure. This causes to effectively change the inductance of stub transmission lines, which changes the phase of the RF signal. These structures can be activated in a symmetric or asymmetrical manner to obtain wide range of phase shifts. A prototype of cascaded four unit cell CRLH transmission line phase shifter with embedded silver-coated ferrites (magnetic particles) is designed, fabricated and tested for phase shifters applications. The measured phase response of the proposed phase shifter is in close agreement with the simulated phase response. Next, for the performance analysis of proposed phase shifter, a 1 × 4 conformal curved-shaped phased array operating at 5.8 GHz is fed with the four unit cell cascaded phase shifter in CST full-wave simulator. The conformal phased array with proposed integrated phase shifters was simulated for broadside pattern correction and main beam scanning at 20 degree on curved-shaped surface with different bend angles. The radiation pattern results obtained with the proposed integrated phase shifters are in close agreement with those obtained with direct excitation of the array.

Comprehensive optimization framework for transmission expansion planning with fractional frequency transmission system

AbstractThe Fractional Frequency Transmission System (FFTS) operates with low frequency to decrease the electrical length of AC transmission lines, consequently enhancing transmission capacity. The integration of renewable energy sources via FFTS will significantly impact power system planning. This paper presents a Fractional Frequency Transmission Expansion Planning (FF‐TEP) model, which considers the interaction between FFTS and the industrial‐frequency power grid. This model addresses the challenges posed by the integration of offshore wind power through FFTS, and takes several key factors into account, including the active power coupling of Modular Multilevel Matrix Converter (M3C), inverter capacity, and converter transformer capacity. To address the non‐convexity caused by AC power flow, this paper introduces a Genetic‐Particle Swarm Optimization algorithm (G‐PSO) with dynamic penalties tailored to the M3C structure. This approach incorporates both crossover and mutation operators from Genetic Algorithms (GA) into Particle Swarm Optimization (PSO). The penalty function dynamically adapts according to the M3C structure, resulting in improved global optimization while maintaining computational efficiency. The results of two case studies demonstrate that FFTS can significantly enhance transmission capacity while reducing cable charging power. This reduces investment costs and decreases voltage offset issues.

A Line Length Independent, Pseudo-Transmission Permittivity Sensor Basing on Dielectric Waveguides

This contribution introduces a novel, dielectric waveguide based, permittivity sensor. Next to the fundamental hybrid mode theory, which predicts exceptional wave propagation behavior, a design concept is presented that realizes a pseudo-transmission measurement approach for attenuating feed-side reflections. Furthermore, a transmission line length independent signal processing is introduced, which fosters the robustness and applicability of the sensor concept. Simulation and measurement results that prove the sensor concept and validate the high measurement accuracy, are presented and discussed in detail.

Electrification of the Orenburg village in 1959-1965

Relevance. The enormous scientific significance of this topic is caused by the correlation of the processes of electrification and modernization of the Soviet village: the widespread use of electricity allowed not only to improve the living conditions of peasants, but also to increase labor productivity. All this together had an impact on the overall level of economic development and contributed to scientific and technological progress. The 1950s and 1960s. They became crucial in relation to the topic under consideration, because it was then that quantitative and qualitative changes took place in comparison with the previous period: the continuous electrification of the village began by connecting collective farms and state farms to high-voltage centralized power plants. This process was most active during the implementation of the seven-year plan for the development of the national economy, which determines the choice of chronological framework.The purpose of the study: to study the process of electrification of the Orenburg village in 1959-1965. Rural electrification in this work is understood as the process of distribution and use of electricity in rural areas: in industrial needs, in households, household premises, cultural, educational and medical institutions.Objectives: to make a periodization of the electrification process of the Orenburg village in the era of the "thaw"; to identify the dynamics of the provision of collective farms and state farms of the Orenburg region with electricity; to trace the development of centralized power supply of the Orenburg village in 1959-1965 and the increase in the length of power transmission lines; to determine changes in the total electricity generation in the Orenburg region during the period under review.Methodology. The work used a set of general scientific and special methods and principles: the principle of objectivity, historicism, historical-comparative, chronological, statistical and other methods.Results. In the course of the study, the process of electrification of the Orenburg village in 1959-1965 was comprehensively studied, its features, results and difficulties were revealed.Conclusion. The continuous electrification of the Orenburg village, despite a number of difficulties, allowed the Orenburg Region not only to overcome the lag behind other administrative-territorial subjects of the Southern Urals, but also to fully provide collective farms and state farms with electricity.

Scanning of the Near-field Focused Beam by Changing Frequency

A new antenna array system is introduced which enables the movement of a near-field focused beam by change of frequency. The shift in the beam is achieved by using multi-wavelength transmission lines between successive elements of the array. At the designed frequency the beam is focused at the focal point. Due to the differences in the transmission line lengths feeding the antenna elements, a progressive phase change occurs between these elements. These phase differences between the elements cause a shift in the beam position. An 8×8 patch antenna array system was designed at 2.4 GHz on a microstrip to implement the proposed system. Two substrates were used: one for the patch antenna array and the other one for the feed network and transmission lines. A full-wave simulation model was used to analyze this design and demonstrate the movement of the beam. For this design, the focused beam is moved 310 mm by changing the frequency from 2.2025 GHz to 2.5750 GHz.

Transmission line fault cause identification method based on transient waveform image and MCNN-LSTM

Power system operators commonly employ fault recorders to record and analyze transmission line faults. However, the length of transmission lines, the number and location of power sources and the sampling frequency of fault recorder will influence the characteristics of the fault waveform leading to fault identification error. This paper proposed a multi-head convolutional neural network with long short-term memory (MCNN-LSTM) using transient waveform image as input for transmission line fault type and fault cause classification. First, the characteristics of transmission line faults were analyzed. Second, MCNN-LSTM is designed by considering interaction between electrical signal. Finally, the modified IEEE-39 node power network was adopted to test the proposed method. The test results show that: this method can improve the identification accuracy of transmission line faults even if there is class unbalance in fault sample set, and shows strong adaptability when transferred to small-size fault samples of transmission lines.

Transmission Line Instance Segmentation Algorithm Based on YOLACT

In the field of intelligent power patrol inspection, the transmission line is an important identification and detection target. The measurement of line spacing and ground distance are key technologies in the field of inspection. Therefore, it is necessary to quickly and accurately segment transmission lines. The transmission lines occupy a large span and vary widely in length. To improve the segmentation rate and accuracy of the transmission lines, we adopted EfficientNet as the main network. With the same accuracy, the number of parameters is reduced by 80% compared with ResNet 101. The network training cost is reduced, and the detection rate of the model is improved. To deal with the influence caused by the large change in transmission line length, we introduce adaptive anchor box calculation and the FPN + PAN structure. At the same time, multiple transmission lines are often overlapped, so the traditional NMS makes it easy to cause the omission or confusion of lines. We improve the NMS. Finally, we adopted the modified CIoU loss function to optimize the loss function. From the experimental results, our model has good performance for instance in segmenting transmission lines.

Use of electrical measurements for non-invasive estimation of plasma electron density in the inductively coupled SPIDER ion source

SPIDER (source for the production of ions of deuterium extracted from RF plasma) is the full-scale prototype of the ITER neutral beam injector ion source. The plasma heating takes place inside eight drivers via inductive coupling, through the radiofrequency (RF) coil. To achieve optimum conditions during source operation it is necessary to know the plasma behavior under various operational conditions. One of the essential parameters is the plasma electron density. It is possible to experimentally measure this parameter and, currently, different methods are being explored, such as the estimations coming from a Langmuir probe and optical emission spectroscopy. However, these methods are either available for temporary measurements or require dedicated analyses with large uncertainties. In this regard, alternative, reliable, and fast diagnostic tools will be beneficial for the estimation of the order of magnitude of electron density inside the driver. Two models for the estimation of electron density are recalled, discussed, and further modified in this work: one is based on the classical power balance equation, and the other is recently described in the literature and relies on classical plasma conductivity. Both models use equivalent electrical parameters of the driver derived from available electrical measurements at the output of the RF generator and through the knowledge of the matching network and the transmission line length. This work explicitly focuses on the application of these models to estimate the plasma electron density in a single driver of SPIDER. Furthermore, the estimations are compared with the first experimental results obtained from temporary electrostatic probe measurements and are found to be in good agreement in terms of magnitude and trends.