Transmission Line Modeling and Algorithm Analysis Considering Parameter Asymmetry and Transient High-frequency Components

In this paper, we present the behaviour of the lossless and lossy multiconductor transmission lines in frequency domain. This study is based on a characteristics method, this method is permits modeling the line as a quadripole whose advantage is not to presuppose applied charges conditions in its extreme. This permits it to be introduced easily in the circuit simulators as Spice, Esacap and Saber. Diverse examples of applications, in the literature, are presented to validate these method and to show their interests and to understand the behaviour of a line MTL in the frequency domain.

The transient components are introduced in the extra high voltage (EHV) transmission lines during the faulty conditions. The transients may damage the power system equipments as well as may also lead to the mal-operation of equipments utilized for a specific application in the power network. Analysis of faults in the presence of series compensation in the EHV transmission line may help to design suitable series compensation. This paper addresses the effect of power system faults on the voltage and current waveforms in the presence of series compensation of EHV transmission lines. The detailed simulation study of transmission line faults with and without series compensation has been carried out in MATLAB/Simulink environment. The simulation results show impacts of faults on the system voltages and load currents with and without series compensation of the lines.

<span lang="EN-US">Since transmission lines account for 80–86% of power system problems, protecting transmission lines is a critical concern. This research proposes a method to identify and categorize various short circuit defects on transmission lines. Various operational and fault circumstances on the transmission of high voltage lines, including L-L fault, single phase to earth fault, and double line fault, double line Three fault scenarios triple line fault, triple line to ground fault, and triple line are simulated using MATLAB software. These flaws damage the linked devices to the power grid. The main motto of this work is to analyze various kinds of faults and also to detect the type of the fault in transmission line. In order to simulate and evaluate the various faults, a 100 km transmission line model was created. A sim power system block library had a fault block, and the harmonic content of the various faults was studied using the FFT tool, the effect of faults was observed. Based on the analysis, a hardware model is designed to identify the faults in transmission line using actuating relays and Atmega 328P microcontroller and display the fault type and parameters like fault impedance, and distance at which fault occurred.</span>

Preface. Chapter 1: INTRODUCTION. 1.1 A Brief History of Electric Power Systems. 1.2 The Structure of the Power System. 1.3 Outline of the Text. Chapter 2: BASICS OF ELECTRIC ENERGY SYSTEM THEORY. 2.1 Introduction. 2.2 Concepts of Power in Alternating Current Systems. 2.3 Three-Phase Systems. 2.4 The Per Unit System. 2.5 Electromagnetism and Electromechanical Energy Conversion. 2.6 Permeability and Magnetic Field Intensity. 2.7 Flux Linkages, Induced Voltages, Inductance, and Energy. 2.8 Hysteresis Loop. 2.9 Eddy Current and Core Losses. 2.10 Energy Flow Approach. 2.11 Multiply Excited Systems. 2.12 Doubly Excited Systems. 2.13 Salient-Pole Machines. 2.14 Round or Smooth Air-Gap Machines. 2.15 Machine-Type Classification. 2.16 P-Pole Machines. 2.17 Power System Representation. Problems. Chapter 3: POWER GENERATION AND THE SYNCHRONOUS MACHINE. 3.1 Introduction. 3.2 The Synchronous Machine: Preliminaries. 3.3 Synchronous Machine Fields. 3.4 A Simple Equivalent Circuit. 3.5 Principal Steady-State Characteristics. 3.6 Power-Angle Characteristics and the Infinite Bus Concept. 3.7 Accounting for Saliency. 3.8 Salient-Pole Machine Power Angle Characteristics. Problems. Chapter 4: THE TRANSFORMER. 4.1 Introduction. 4.2 General Theory of Transformer Operation. 4.3 Transformer Connections. Problems. Chapter 5: ELECTRIC POWER TRANSMISSION. 5.1 Introduction. 5.2 Electric Transmission Line Parameters. 5.3 Line Inductance. 5.4 Line Capacitance. 5.5 Two-Port Networks. 5.6 Transmission Line Models. Problems. Chapter 6: INDUCTION AND FRACTIONAL HORSEPOWER MOTORS. 6.1 Introduction. 6.2 Three-Phase Induction Motors. 6.3 Torque Relations. 6.4 Classification of Induction Motors. 6.5 Rotating Magnetic Fields in Single-Phase Induction Motors. 6.6 Equivalent Circuits for Single-Phase Induction Motors. 6.7 Power and Torque Relations. 6.8 Starting Single-Phase Induction Motors. 6.9 Single-Phase Induction Motor Types. Problems. Chapter 7: FAULTS AND PROTECTION OF ELECTRIC ENERGY SYSTEMS. 7.1 Introduction. 7.2 Transients during a Balanced Fault. 7.3 The Method of Symmetrical Components. 7.4 Sequence Networks. 7.5 Line-to-Ground Fault. 7.6 Double Line-to-Ground Fault. 7.7 Line-to-Line Fault. 7.8 The Balanced Three-Phase Fault. 7.9 System Protection, An Introduction. 7.10 Protective Relays. 7.11 Transformer Protection. 7.12 Transmission Line Protection. 7.13 Impedance-Based Protection Principles. 7.14 Computer Relaying. Problems. Chapter 8: THE ENERGY CONTROL CENTER. 8.1 Introduction 8.2 Overview of EMS Functions. 8.3 Power Flow Control 8.4 Power Flow 8.5 Stability Considerations 8.6 Power System State Estimation 8.7 Power System Security 8.8 Contingency Analysis 8.9 Optimal Preventive and Corrective Actions 8.10 Dynamic Security Analysis Chapter 9: THE PRESENT AND FUTURE OF ELECTRIC ENERGY SYSTEMS. 9.1 Introduction. 9.2 Challenges Facing the System. 9.3 Blackouts and their Impact. 9.4 Mitigating and Coping. REFERENCES. INDEX.

Power systems are becoming increasingly complex due to the integration of several power electronic devices. Protection of such systems and augmentation of reliability and stability depend on limiting the fault currents. Analysis of faults is essential for the selection of appropriate relays and other safety systems. In this research work fault analysis, fault detection, and data prediction of long transmission lines are discussed. Different parameters are analyzed at each point of distance using MATLAB/Simulink for long transmission lines. Through these results, it is concluded that with the increase in distance, the parameters change, so the detection response of the Mho relay also varies. Moreover, in this research work, the Mho relay response at different points is tested through Simulink software for long transmission lines. As it is concluded that manually it is very difficult to test the response of Mho relay at each point, the artificial intelligence technique of long short-term memory (LSTM) is used for the prediction of the data for the next long transmission line. Lastly, in this work, a long short-term memory network is used to predict the parameters. The LSTM is then used to find the predicted data of subsequent transmission line from previous data. The artificial intelligence technique successfully utilized for the detection of long transmission line fault.

Transmission line (TL) parameters are the basis of power system calculation. In recent years, artificial intelligence has been widely applied and plays a great role in the power system. However, artificial intelligence is rarely applied to transmission line parameter identification. Therefore, from the perspective of line model and artificial intelligence, combined with median estimation and modified Supervisory Control And Data Acquisition (SCADA) data based on TL model, this paper proposes a robust method for parameter identification of TL based on Radial Basis Function (RBF) neural network and modified SCADA data. Firstly, the line parameter identification method based on RBF neural network is proposed. Then, the training set is established through the π-equivalent model in consideration of different operating conditions and different circuit parameters. Furthermore, the input data of RBF neural network is construed by modifying the SCADA data based on TL model. In addition, the median estimation robust method, which can estimate the final result and reduce the noise interference, is introduced. Finally, the validity and practicability of the proposed method are verified by simulation data and measured SCADA data respectively.

This paper presents an analysis of resonant faults and their transient responses on half-wavelength lines. This type of transmission line has been studied for many years in countries that need alternatives for bulk power transmission over very long distances. An important issue for this technology is the occurrence of critical faults, which produce peculiar behavior in the main electrical entities and can jeopardize line insulation and compromise system stability. Here, the main factors influencing the severity of faults are analyzed: the type of fault and fault location. This paper shows that faults involving positive and negative sequences are the most critical when applied at specific regions and produce high voltage and power with a high rate of rise. The necessity for a mitigation method that removes this severe resonant fault condition until the operation of a protection system is discussed, and such a method is established. A method using two spark gaps with a new and improved location criterion is proposed, tested and evaluated, providing promising results for controlling voltage and power at terminal substations. Digital simulations are performed with PSCAD/EMTDC.

The test and analysis of the power quality of some 1000kV UHV transmission lines and 500kV EHV transmission lines is carried out. It is found that there is harmonic voltage excess problems when the power supply of the UHV and EHV voltage line is single-ended or single-loop, the problem basically disappeared after the operation mode change, different operating conditions, the harmonic current has not been greatly affected, indicating that the harmonic voltage changes mainly caused by the system harmonic impedance. With the analysis of MATLAB Simulink system model, it can be seen that there are specific harmonic voltage excess in the system under the specific operating mode, which results in serious distortion of the specific harmonic voltage. Since such phenomena are found in 500kV and 1000kV systems, it is suggested that the test evaluation work should be done under the typical mode of operation in 500kV, 1000kV Planning and construction process to prevent the occurrence of serious distortion and the regional harmonic current monitoring and suppression work should be done.

Efficient and reliable electricity transmission is a fundamental requirement for modern power systems, particularly for long-distance networks where transmission losses and voltage regulation challenges significantly impact overall system performance. This study proposes an enhanced ABCD parameter-based transmission line model, integrating an equivalent π -model, to improve the accuracy of power loss calculations, voltage regulation, and transmission efficiency. Unlike traditional models, this approach accurately captures the effects of temperature variations, aging infrastructure, and real-time load conditions, ensuring more precise power system analysis. Extensive simulations in MATLAB/Simulink validate the model’s effectiveness, demonstrating an efficiency improvement of up to 88.8% for long transmission lines, ensuring compliance with IEEE standards. Furthermore, the model features an automated alert system that warns users if efficiency drops below 95%, making it a practical tool for grid operation and planning. These findings underscore the model’s potential for optimizing transmission line design, particularly in rural electrification projects and renewable energy integration, where efficient power delivery is crucial.

This paper presents a novel non‐unit protection scheme for the protection of LCC‐HVDC transmission lines. The fault‐generated travelling waves at the faulty line ends are filtered by a filter–reactor unit. The filtered current waveforms are then processed by a multi‐resolution morphological gradient and are used by a fast non‐unit protection scheme for LCC‐HVDC transmission lines. The proposed method does not require communication links between transmission line ends and uses only current signals with a low sampling rate of 10 kHz. In addition, the proposed scheme is computationally efficient, making it suitable for practical applications. The performance of the proposed protection scheme is validated by comprehensive simulation studies as well as field data on a bipolar LCC‐HVDC system. Both simulation and field data test results verify the accurate performance of the proposed method for different internal fault conditions, including high fault resistances up to 1000 Ω. Furthermore, the proposed scheme is robust against external DC and AC faults, change of sampling frequency and data window length, non‐ideal faults, change of power flow, change of DC filter parameters and smoothing reactor, change of operation mode, and measurement noise.

This paper presents detection of plastic landmines and characterization of subsurface and the target using ground penetrating radar (GPR) measurements. The inverse transmission line (TL) modeling approach is used to analyze the characteristics of practical GPR system operating above non-uniform ground. The modeling approach considers the presence of surface roughness, natural clutter, targets and soil moisture. With this model, the time domain signature of electromagnetic (EM) propagation can be assessed. The inverse TL modeling is applied to estimate the characteristic parameters (such as conductivity, magnetic permeability and permittivity) of the subsurface and buried plastic landmines. TL modeling is applied to obtain the reverse solution of the electromagnetic equations. Different scenarios were considered and test signals of the B-scan data are used to test the effectiveness of the method. Simulations of the real data analysis showed the effectiveness of the model and its application to target detection and characterization of the subsurface. Performance of the modeling is analyzed using receiver operating characteristic (ROC) analysis of the four hypotheses and it has found that 99.5% detection has achieved as the cost of 12% of false alarm. Keywords : Dielectric properties; EM wave propagation; GPR; Parameter estimation; Inverse transmission line.

Flexible heat exchanger network design for chemical processes with operation mode changes

In power systems, analysis of critical faults, mainly, different types of simultaneous faults on transmission lines, is a sensitive issue. To identify the accurate fault place during a simultaneous fault condition, all major algorithms fail to provide the desired results. In this paper, an analysis of simultaneous faults called broken and fallen to earth conductor fault conditions is carried out. With the help of an equivalent sequence components network, generalized impedance equations are derived to determine the accurate fault place on the transmission line during the simultaneous broken and fallen to earth conductor’s fault condition. For authentication of the derived method, simulation has been done using MATLAB tool with two different medium transmission lines. Simulation outputs manifest the accuracy of the proposed generalized impedance equations by showing 98% accuracy for identifying precise fault places. The derived fault analysis method uses the sequential network formation technique, which can be easily understood by researchers.

Investigation on the limitation of closed-form expressions for wideband modeling of overhead transmission lines

This paper presents a rigorous field theoretical analysis of slow wave mode propagation in coplanar waveguide (CPW) metal-insulator-semiconductor (MIS) transmission lines with a laterally confined doping profile. Two types of transmission line structures are investigated-bulk silicon and semiconductor-on-insulator (SOI). In both cases a Gaussian profile of the doping depth is assumed. It was found that an optimum lateral width of the doping region exists for which both structures exhibit a much better slow wave factor at lower losses than traditional thin-film MIS transmission lines. The abrupt transition between MIS, CPW, and CPW on a normal insulating substrate was investigated as well. It was found that the reflection coefficient increases significantly with frequency and when the lateral width of the doping region is extended over the whole cross section of the CPW. The investigation was carried out using the frequency-domain transmission line modeling (TLM) (FDTLM) method.