Transmission Line Calculation Research Articles

Short-Circuit Current Calculation of Flexible Direct Current Transmission Lines Considering Line Distribution Parameters

Short-Circuit Current Calculation of Flexible Direct Current Transmission Lines Considering Line Distribution Parameters

Calculation of Transmission Lines and Electrical Equipment of 150kV Main Guluk- Guluk Madura Island East Java, Indonesia

Guluk-Guluk is supplied by a 20 kV system from the Pamekasan GI and Sumenep GI, resulting in a voltage drop of 5 kV. The fall in the voltage on the load side cannot be overcome through the regulation of transformer tapping or the use of bank capacitors, so the possible way is to build a new GI. The construction of GI Guluk-Guluk requires a new transmission line. A good electric power transmission has a low voltage drop, high efficiency and high surge impedance loading (SIL) values. Efforts to improve the voltage by changing the tapping in the power transformer located at the nearest substation only produce a voltage of 166.07 kV. The provision of bank capacitors in Guluk-Guluk produces a voltage of 17,542 kV. The construction of GI Guluk-Guluk requires a new transmission line that connects Pamekasan to Guluk-Guluk, Sampang to Guluk-Guluk and Guluk-Guluk to Sumenep. The construction of a 150 kV network line requires calculations to determine network configurations, conductors, isolators, tower types, and electrical equipment supporting 150 kV transmission systems such as current transformers, voltage transformers, power breakers, and arresters. In this final project, simulation is done with the help of ETAP 12.6 software. The results of calculations and simulations of the transmission line toward Guluk-Guluk give a voltage drop of 4.89 kV, with an efficiency level of 96.74% and a SIL value of 41.225 MW. so these results are sufficient to be used as a reference for GI development in Guluk-Guluk.

A modified incremental gravitational search algorithm for short-term hydrothermal scheduling with variable head

In this study, the solution of short-term hydrothermal coordination problem (STHCP) with variable head was performed. In the manuscript, incremental gravitational search algorithm (IGSA) which was developed as a new method has been applied to two different power problems. One of the systems used as an example is a variable head STHCP which has previously been solved in the literature by neglecting transmission line losses. The second is a lossy system designed as a variable head STHCP, with the purpose of contributing to the literature. In the lossy system, Newton–Raphson AC power flow method was used to calculate transmission line losses. Possible electrical and hydraulic constraints in the solution of the problem were satisfied using the penalty function method. The results obtained from the solutions of the sample systems were compared and discussed.

Design and implementation of an open source transmission line impedance matching educational framework

AbstractDetermining input impedance, assigning reflection coefficient, and matching load impedance are important transmission line problems those involve complex calculation steps because of complex connection architectures in transmission lines. Efficient understanding of such problems in undergraduate and graduate courses should be supported by rich visualization tools. The Smith chart is a convenient tool for transmission line calculations especially for wave propagation and maximum power theory that discusses impedance matching problems. In this context, we can say that Java is a widely used open source educational tool having strong computational environment for research and development aims. In this study, an open source transmission line impedance matching educational framework (TLIME) has been designed to teach efficiently wave propagation and maximum power theory that discusses the impedance matching problems. The success of developed educational framework has been measured by a questionnaire held in courses in the third and fourth years of the electrical and electronics engineering undergraduate program at Sakarya University of Applied Sciences, Turkey. The visual preparation of the problem solutions with rich graphical user interface and simulations of the mathematical representations has been evaluated to contribute to a better understanding of the wave propagation and impedance matching transmission line subjects. The functionality and simplicity of the developed framework scored by over 82% among course enrolled students. The rest of the paper is organized as follows. Section 2 explains transmission line impedance matching problem in the context of maximum power theory. Section 3 discusses transmission line planning and problem solving with Smith chart. Section 4 discusses explanation and usage of developed TLIME framework and last section discusses results.

Lightning Fault Rate Calculation of Transmission Lines Taking Statistical Variation of Arching-Horn Flashovers into Account

Lightning Fault Rate Calculation of Transmission Lines Taking Statistical Variation of Arching-Horn Flashovers into Account

Robust Identification Method for Transmission Line Parameters That Considers PMU Phase Angle Error

Accurate transmission line parameters are the basis of power system calculations. The measured phasor measurement unit (PMU) phase angle data at both ends of a line may contain large errors caused by synchronization problems, which can seriously affect the accuracy of parameter identification. This paper proposes a robust PMU-based method for calculating transmission line parameters from PMU data at both ends of a line in such a way that a synchronization error between the ends does not degrade the results. Specifically, a $\pi $ -equivalent model for the transmission line is established, and a least square objective function with nonlinear equations for positive parameter identification is derived. Furthermore, to reduce the impact of noise and biased data, median estimation is used to obtain the final result. Finally, a simulation shows the effectiveness and robustness of the proposed method, and its practicality is demonstrated in a case study using measured PMU data.

Negative lumped element matching technique for performance enhancement of ultra-wideband LNA

The paper aims at designing of two stage cascaded ultra-wideband (UWB) low noise amplifier (LNA) by using negative image amplifier technique. The objective of this article is to show the performance improvement using negative image amplifier technique and realization of negative valued lumped elements into microstrip line geometry. The innovative technique to realize the negative lumped elements are carried out by using Richard's Transformation and transmission line calculation. The AWR microwave office tool is used to obtain characteristics of UWB LNA design with hybrid microwave integrated circuit (HMIC) technology. The 2-stage cascaded LNA design using negative image amplifier technique achieves average gain of 23dB gain and low noise Figure of less than 2dB with return loss less than −8dB for UWB 3–10GHz. The Proper bias circuit is extracted using DC characteristics of transistor at biasing point 2V, 20mA and discussed in detail with LNA layout. The negative image matching technique is applied for both input and output matching network. This work will be useful for all low power UWB wireless receiver applications.

Application of adaptive sampling algorithm in solving the scattering field of UHVAC/DC transmission lines

Using MBPE technology can quickly predict the approximation of the frequency response of transmission lines' scattering field. However, equal interval sampling method is usually used in the calculation of transmission lines' scattering field, it results a possibility that the sampled data may be with lack of important points, which makes the fitting results difficult to control, or samples duplicated information to increase the amount of calculation. In order to calculate more accurately, the adaptive sampling algorithm is introduced here. In the fast solution of frequency response of transmission lines' scattering field, it greatly improved the accuracy of results. Finally, compared with those of the traditional interval sampling methods, the results of using adaptive sampling algorithm were in line with the actual situation.

Mutually Coupled Transmission Line Parameter Estimation and Voltage Profile Calculation Using One Terminal Data Sampling and Virtual Black-Box

In this paper, an accurate parameter identification algorithm is proposed for transient voltage profile calculation of the unknown transmission lines. This method is based on the virtual black-box method and uses single-ended data sampling, where the input data include voltage and current samples obtained by measuring at one end of the line in transient mode. A mathematical formulation is proposed to separate the sampled data and form a virtual black-box system with virtual inputs and outputs. The virtual black-box is designed, such that the system coefficients relating the virtual outputs and inputs are the known functions of transmission line parameters in the real world. The coefficient values are then calculated by employing the recursive least squares estimation method, which minimizes the sum of squared errors of observations. Using this method, transmission line parameters and transient voltage profile are calculated from only one terminal data with no need of measuring devices, data synchronization, and communication devices at both sides. The efficiency of the proposed method is tested and proved through the EMTP simulations.

Fractal‐based lightning model for shielding failure rate calculation of transmission lines

In this study, performance of lightning shielding system of transmission lines is investigated by means of a new fractal-based model of simulated lightning. A new lightning downward stepped leader based on fractal approach is introduced in this study. The zigzag movement of lightning downward leader as well as branching nature are simulated using the proposed model. Moreover, a new charge distribution is proposed for branched lightning channel. In addition, the branch fading during lightning downward movement is also simulated in order to simulate the lightning closer to reality. The proposed method is applied for calculating the striking distance for a transmission line and the results are compared with those of leader progression model and different models of electrogeometric model. Furthermore, the shielding failure rate of some practical structures obtained by the proposed method is compared with the field observations. The results are discussed and superiority of the proposed simulated lightning model is concluded.

Investigation of Sinusoidal Phase Voltage Effect on SFR Calculation of HVAC Transmission Lines

Objectives: In this paper, the conductor\'s voltage effects on shielding failure calculation of high voltage transmission lines are investigated. A new criterion for distinguishing the stable upward leader formation is also proposed. Methods/ Statistical Analysis: Charge simulation method is used for modeling of the 3-D stepwise movement of lightning downward leader. For determination of striking point and Shielding Failure (SF) calculation, a new criterion for distinguishing the stable upward corona-leader system formation is proposed. The proposed criterion is developed in a way that the effects of operating voltage including the magnitude, phase and the sign of voltage are considered in the stable upward leader formation. Findings: The results of the simulated lightning, using the proposed criterion show that the proposed model simulates the lightning stroke phenomenon close to reality. The amount of the required electric field for stable upward leader inception from the phase wires with various voltage levels and signs, are calculated by proposed criterion. The results, in line with field experiments, revealed that the probabilities of upward leader inception and also lightning strokes change with variation of operating voltage of conductors. In the conductors with positive voltage, the required electric field for upward leader inception is far lower than the conductors with zero or negative voltage. Moreover the SF of a 500KV-HVAC transmission line is obtained and compared in two cases i.e., with consideration and without consideration of voltage effects. The result showed that SFR and maximum return stroke current increase 19% and 14%, respectively, by consideration of phase voltage effects. Which means voltage has great effects on SF calculation and should not be neglected. Novelty/Improvements: The proposed method improved SF Calculation by 1-Considering the effects of operating voltage including the magnitude, phase and sign of voltage2-Accurate modeling of downward leader and its charge in space. Keywords: Lightning, Leader Progression Model, Shielding Failure Calculation, Sinusoidal Voltage of HVAC Transmission Line

Study on Reactive Power and Harmonic Characteristics of DC Ice-melting Technology based on RTDS Simulation and Field Test

To study the characteristics of reactive power and harmonic of 500kV DC de-icer, the ice-melting technologies including the calculation method of critical ice-melting current, ice-melting time and maximum ice-melting current are clarified. The detail ice-melting methods and strategies for the 500kV transmission lines are proposed. Based on the ice-melting current calculation of Kang-Ding substation transmission lines in Sichuan, China, the 500kV/150MVA DC de-icer is deployed for the 500kV transmission lines. The effectiveness and feasibility of the ice-melting algorithm is validated by the RTDS simulation and the field test results. It is proved that the harmonic distortions of voltage and current are increased with the increasing ice melting current, which can be improved by the installation of passive filters.

Multipactor threshold calculation of coaxial transmission lines in microwave applications with nonstationary statistical theory

This paper presents a statistical theory for the initial onset of multipactor breakdown in coaxial transmission lines, taking both the nonuniform electric field and random electron emission velocity into account. A general numerical method is first developed to construct the joint probability density function based on the approximate equation of the electron trajectory. The nonstationary dynamics of the multipactor process on both surfaces of coaxial lines are modelled based on the probability of various impacts and their corresponding secondary emission. The resonant assumption of the classical theory on the independent double-sided and single-sided impacts is replaced by the consideration of their interaction. As a result, the time evolutions of the electron population for exponential growth and absorption on both inner and outer conductor, in response to the applied voltage above and below the multipactor breakdown level, are obtained to investigate the exact mechanism of multipactor discharge in coaxial lines. Furthermore, the multipactor threshold predictions of the presented model are compared with experimental results using measured secondary emission yield of the tested samples which shows reasonable agreement. Finally, the detailed impact scenario reveals that single-surface multipactor is more likely to occur with a higher outer to inner conductor radius ratio.

Development of a Software Tool for Calculating Transmission Line Parameters and Updating Related Databases

Abstract Transmission lines are essential components of electric power grids. Diverse power system applications and simulation based studies require transmission line parameters including series resistance, reactance, and shunt susceptance, and accurate parameters are pivotal in ensuring the accuracy of analyses and reliable system operation. Commercial software packages for performing power system studies usually have their own databases that store the power system model including line parameters. When there is a physical system model change, the corresponding component in the database of the software packages will need to be modified. Manually updating line parameters are tedious and error-prone. This paper proposes a solution for streamlining the calculation of line parameters and updating of their values in respective software databases. The algorithms used for calculating the values of line parameters are described. The software developed for implementing the solution is described, and typical results are presented. The proposed solution is developed for a utility and has a potential to be put into use by other utilities.

Ground-Wave Propagation Effects on Transmission Lines through Error Images

Electromagnetic transient calculation of overhead transmission lines is strongly influenced by the natural resistivity of the ground. This varies from 1–10K (Ω•m) depending on several media factors and on the physical composition of the ground. The accuracy on the calculation of a system transient response depends in part in the ground return model, which should consider the line geometry, the electrical resistivity and the frequency dependence of the power source. Up to date, there are only a few reports on the specialized literature about analyzing the effects produced by the presence of an imperfectly conducting ground of transmission lines in a transient state. A broad range analysis of three of the most often used ground-return models for calculating electromagnetic transients of overhead transmission lines is performed in this paper. The behavior of modal propagation in ground is analyzed here into effects of first and second order. Finally, a numerical tool based on relative error images is proposed in this paper as an aid for the analyst engineer to estimate the incurred error by using approximate ground-return models when calculating transients of overhead transmission lines.

Fractional Lumped Parameter Modeling of Transformer Windings under VFTO

Very fast transient overvoltage (VFTO) is very dangerous for the transformer which is directly connected to gas insulated substations (GIS). At the same time, due to the continuous increasing of operating frequency in the power system, under the high frequencies of the transmission line calculation and simulation process, it is necessary to consider the frequency-dependent properties of the parameter. In order to study the voltage distribution in transformer windings under VFTO, a new Lumped parameter model which takes into account the fractional characteristics is proposed, named fractional lumped parameter model (FLP). The model divides each turn of transformer windings into proper sections, whose parameters are all lumped parameters. Finally it shows the correctness and validity of the model through the comparation of the experiment datas and simulation results.

Frequency-Dependent Transmission Line Fractional Model and its Solution Based on Skin Effect

Due to the continuous increasing of operating frequency in the power system and the transmission speed, under the high frequencies of the transmission line calculation and simulation process, it is necessary to consider the frequency-dependent properties. At present, the frequency-dependent transmission line modeling has a variety of methods, but in the modeling and calculation of frequency variable term, processing is relatively complicated. This article will introduce transmission line equation of fractional calculus, intuitive representation of frequency varying parameters, and by a time-domain fractional solution, simplify the operation, improve the computational efficiency. Application of this algorithm for fractional differential equations can be obtained the voltage and current responses at any point in the transmission line. Thesis also by comparison with actual example, confirmed the validity and feasibility of the algorithm. At the same time, proposed algorithm can be extended to the multiple conductor transmission lines of fractional order model, also has certain applicability.

Modification of the Perrine–Baum Diagram to Improve the Calculation of High-Voltage Transmission Lines

Throughout the history of electrical engineering education, vector and phasor diagrams have been used as a fundamental learning tool. Currently, computational power has replaced these with long data lists, the result of solving equation systems with numerical methods. In this sense, diagrams have been relegated to an academic background topic that, although theoretically explained, is not used in practice. This fact may work against the understanding of the complex behavior of electrical power systems by students. This paper proposes a modification of the classic Perrine-Baum diagram construction to allow both a more practical representation and a better understanding of the behavior of a high-voltage transmission line under different load levels. A tool capable of evaluating the moment in time when demand exceeds the line's carrying capacity is also introduced. In addition, the impact of this tool on the learning process is evaluated.

The Electromagnetic Environmental Impact of High-Voltage Transmission Line and its Prevention Methods

This paper calculates frequency electric field intensity by the equivalent charge method, and analyzes the main factors affecting the electromagnetic environment of the 500kV Double Circuit Transmission Lines. In the same electromagnetic transmission line calculation parameters, optimization of phase sequence can effectively reduce the frequency electric field intensity; with the increase of the distance, the line frequency electric field intensity significantly reduces away from the center line within 25m. Finally, the paper obtains the phase sequence arrangement with minimal impact on the electromagnetic environment and the minimum ground clearance meeting the environmental requirements.

Analysis on the Electromagnetic Environmental Factors of 500kV Double Circuit Transmission Line

This paper calculates frequency magnetic field strength by the Ampere's law, and analyzes the main factors affecting the electromagnetic environment of the 500kV Double Circuit Transmission Lines. In the same electromagnetic transmission line calculation parameters, optimization of phase sequence can effectively reduce the frequency magnetic field strength; with the increase of the distance, the line frequency magnetic field strength significantly reduces away from the center line within 25m. Finally, the paper obtains the phase sequence arrangement with minimal impact on the electromagnetic environment and the minimum ground clearance meeting the environmental requirements.