Three-phase Transmission Line Research Articles

Recursive Estimation of Three Phase Line Admittance in Electric Power Networks

Synchronized phasor measurements in power transmission and distribution networks enable real-time monitoring of voltage and currents. Such measurements can be used to monitor power flow, but also to monitor important electric parameters of the network. In this paper, it is shown how synchrophasor measurements can be used for real-time monitoring of the admittance of the connections between buses in a power network, typically the three-phase transmission or distribution lines. The objective is to formulate admittance monitoring capabilities in which changes in three-phase line admittance can be monitored in real-time and achieved by the formulation of synchrophasor-based recursive estimation techniques over short time intervals.

An alternative procedure to obtain the ABCD matrix of multiphase transmission lines: Validation and applications

This paper presents an alternative procedure for obtaining the ABCD matrix of a generic multiphase transmission line. The ABCD matrix is obtained from the open and short-circuit responses of the line calculated in the frequency domain. The proposed procedure was used to obtain the ABCD matrix of a typical 440 kV overhead three-phase transmission line. To ensure that the proposed procedure was developed correctly, the ABCD matrix was used to represent the transmission line in simulations of electromagnetic transients resulting from switching and lightning. These simulations were also carried out with two known models that yielded identical results. The comparisons showed that the proposed methodology was developed correctly and that its main advantage is that it can be applied to generic multiphase transmission lines, whereas the existing methodology in the literature is restricted to three-phase lines with vertical planes of symmetry.

Magnetic-Field-Sensing-Based Approach for Current Reconstruction, Sag Detection, and Inclination Detection for Overhead Transmission System

Noncontact monitoring technique of mechanical and electrical states is increasingly attractive for the overhead transmission system. This paper proposes a new technique to detect the tower inclination and transmission line sag, and measure transmission current simultaneously. The key of this technique is to use the ground magnetoresistive (MR) sensor to measure the magnetic flux density along the center line from the three-phase transmission lines. Moreover, the magnetic field (MF) calculation formulas for a tilted tower are given in this paper. Finally, with MF calculation formulas, an algorithm based on artificial immune system (AIS) is applied to estimate the transmission line sag and tower tilt angles, and reconstruct currents. Model simulations of an overhead transmission system are carried out to verify the idea. The simulation results validate the feasibility of this noncontact approach to estimate mechanical parameters and reconstruct electrical parameters for overhead transmission system.

Application of modal‐phase domain relations to estimate transmission line parameters

The accuracy of transmission line parameters (TLPs) allows the proper response to faults or load variations and the monitoring of common fault indicators, such as the conductor's temperature and sag. TLP estimation methodologies based on modal decomposition theory are restricted to specific tower configurations in which the transmission line transformation matrix is known. This paper proposes a non-linear system of equations to estimate the parameters of a generic three-phase transmission line while using modal-phase relations for an unknown transformation matrix and known voltages and current phasors at the terminals of the line. The Newton–Raphson (NR) method is implemented to solve this proposed system of equations and accurately estimate the TLPs. The relative error of the estimated parameters shows the methods’ accuracy and the influence of the line representation as lumped elements. The results demonstrate the robustness and efficiency of the proposed method for transmission lines of different lengths.

Fault Detection on a 132kV Transmission Line Using Artificial Neural Network

This paper utilises an artificial neural network (ANN) technique for fault detection on a 132kV transmission line system. A Feed-forward network with backpropagation algorithm was used in the fault recognition process for the Uyo to Eket 132kV transmission line on the Nigerian Power System under review. Due to a dearth in real-time data from the transmission line system under review, faults values (current and voltage) were generated using power system computer-aided design (PSCAD)/electromagnetic transient design and control (EMTDC) software model of the transmission line, with variations in fault resistance, distance and inception angle. The generated fault and no-fault data set were extracted using MATLAB software. The neural network toolbox in MATLAB was utilised for training the ANN-based relay system to detect faults on the three-phase transmission line system. The results obtained showed that the trained network with hidden layers architecture [15 15 10 5] has the best performance with mean square error (MSE) value of 0.000145 and correlation coefficients for validation and testing of 0.99998 and 0.99953 respectively. These results justify the reliability and accuracy of ANN-based protection relays for transmission lines fault detection.

Calculation of Power Frequency Electric Field Around Ultra-High Voltage AC Transmission Lines

Under the increasingly stringent situation of environmental protection management, it is necessary to research the distribution law of power frequency electric field around Ultra-High Voltage (UHV) AC transmission lines to provide technical basis for the design of transmission lines and the environmental impact assessment. Firstly the basic principle of equivalent charge method and its mathematical model are introduced in this paper. Then it is researched how to use equivalent charge method to analyze the electric field near the transmission lines. Based on the three-phase double-circuit overhead transmission line model, the influences of several factors on the power frequency electric field have been analyzed. These factors include the conductor-to-ground height, the phase sequence arrangement, the number of split conductors and the split spacing. Finally the frequency electric field of parallel UHV AC transmission lines is discussed. The results can provide reference for engineering design of UHV AC transmission lines.

Assessment of reliability of an overhead transmission line with a split back-up phase

Transmission of electrical energy is the most important component of an electric power system. Optimization, modernization of the electric power transport system, increasing the capacity, as well as variability of connection arrangements, while maintaining the required level of reliability and safety, is regarded today as an urgent task for the energy industry as a whole. The article is devoted to the problem of determining the efficiency of the circuit design solution for a double-circuit three-phase power transmission line with an additional mode of operation — «with a split back-up phase» and determining its main reliability indicators. A circuit design solution for a double-circuit power transmission line with expansion of operating modes is presented in detail. The functional redundancy of the transmission line in accordance with the circuit design solution is based on switching of a conventional double-circuit power transmission line in the emergency mode to the single-circuit split-phase mode, which is the second working circuit. The ways of increasing the natural power of a double-circuit power transmission line are considered. The results of calculation of the capacity of a line with a split back-up phase and a comparison of the main parameters of overhead transmission lines with an additional mode of operation — with a split back-up phase — and power lines in conventional modes of operation, are presented. The results of calculations of reliability indicators are presented, such as the probable relative number of hours of interruption of power supply and the undersupply of electrical energy. A comparison of options have shown that the probable relative under-supply of the electric power of a double-circuit overhead transmission line with an additional operating mode — with a split back-up phase, is lower by approximately 13% than that of a conventional double-circuit power line, which will positively affect the maneuverability and reliability of the entire system.

Research on Transmission Line Voltage Measurement Method Based on Improved Gaussian Integral

Currently, there are two non-contact measurement methods of the transmission line voltage based on field sensor: one is calculation with the inverse problem of electric field for the solution, and the other is to solve by the numerical integration algorithm. In general, the first one is confronted with data equation solving problems and difficulties in accurate calibration as well as low precision, while the second one is troubled by the complexity of algorithm equation and unsatisfactory integration node. In view of the above problems, this paper improves on the basis of the Gaussian integral algorithm to seek better nodes, in order to reduce the difficulty of solving and improve the measurement accuracy of the integral algorithm. First, starting from the Gaussian integral algorithm and making research to improve the Gaussian integral algorithm theory. Then, the finite element simulation of three-phase transmission line through Maxwell software is built, and the space electric field distribution data is acquired to calculate an integral node as well as its corresponding weights. Finally, the three-phase transmission line voltage measurement test platform with D-dot sensor voltage measurement system is built to test verification. The text results show that the voltage measurement method based on the improved Gaussian Integral has characteristics of a simple solution, better integral node, and higher precision, and all the measured voltage errors are less than 0.45%.

Enhanced R package-based cluster analysis fault identification models for three phase power system network

The main objective of this research work is to develop an R-based fault identification model for power system in a cluster analysis environment. Cluster analysis-based data mining techniques model has been implemented to locate the three-phase transmission lines fault in IEEE 30 bus power system. Power World version 18 software was used to simulate the IEEE 30 bus power system and the three-phase transmission lines fault. The bus voltages at fault were collected and import to R statistical software to identify the faults at buses. Through cluster analysis using squared euclidean distance method, fault has been identified at each bus. Then the data also imported to R statistical package to compute the cophenetic distance of dendrogram and check the accuracy of clustering. This meant that the application of data mining techniques yields a huge potential in solving complex problems related to power system, it not only yield an accurate result but also fast computation. The proposed innovative successful model was able to locate the fault at each bus by bus nominal voltage comparison method.

Enhanced R package based Cluster Analysis Fault Identification Models for 3 Phase Power system Network

The main objective of this research work is to develop an R-based fault identification model for power system in a cluster analysis environment. Cluster analysis-based data mining techniques model has been implemented to locate the three-phase transmission lines fault in IEEE 30 bus power system. Power World version 18 software was used to simulate the IEEE 30 bus power system and the three-phase transmission lines fault. The bus voltages at fault were collected and import to R statistical software to identify the faults at buses. Through cluster analysis using squared euclidean distance method, fault has been identified at each bus. Then the data also imported to R statistical package to compute the cophenetic distance of dendrogram and check the accuracy of clustering. This meant that the application of data mining techniques yields a huge potential in solving complex problems related to power system, it not only yield an accurate result but also fast computation. The proposed innovative successful model was able to locate the fault at each bus by bus nominal voltage comparison method.

PROTECTION OF WIND-FARM INTEGRATED SERIES CAPACITOR COMPENSATED THREE-PHASE TRANSMISSION LINE USING DAUBECHIES-10 WAVELET TRANSFORM

This work presents a Db7WT (Daubechies-7 wavelet transform)-based fault recognition technique for wind farm-integrated series capacitor-compensated three-phase transmission line (WFISCCTPTL). The single-side recorded fault currents of the WFISCCTPTL are used to evaluate the amplitudes of Db7WT coefficients. The fault factors of WFISCCTPTL are varied. It is investigated that the Db7WT well detects every type of fault. It is also explored that the Db7WT is robust to the variation in fault factors of WFISCCTPTL.

Utilization of PMU Measurements for Three-Phase Line Parameter Estimation in Power Systems

A new method is developed for synchrophasor-based estimation of three-phase transmission line (TL) impedance parameters, applicable for both fully transposed and untransposed TLs. The method is based on accurate time-synchronized measurements of the voltage and current phasors at both ends of a TL. The method estimates the line impedance values using a robust estimator with the property that the influence of outliers on the final results is minimized. A robust estimator is chosen as an alternative to well-known ordinary least-squares estimators which are highly sensitive to outliers. The performance of the method has been evaluated using a laboratory setup simulating real power system conditions. The necessary conditions for algorithm convergence as well as the requirements for measurement accuracy have been studied. In addition, this paper describes validation results of the proposed method in real high-voltage power system conditions by measuring voltage and current phasors with two phasor measurement units installed on both terminals of a 400-kV fully transposed overhead TL.

Calculation of Parameters of Six-Phase Transmission Line Using Carson’s Line Model

In this paper calculation of parameters of a six-phase transmission line is presented. The calculation is carried out by extending the Carson’s line model in three-phase system. An existing three-phase double-circuit transmission line with two ground wires of Malaysian network, which belongs to TNB (Malaysian power utility), is chosen as a case study. The result of calculation of parameter of the line revealed that the positive sequence inductive reactance is somewhat higher for 6-phase single-circuit line than for a 3-phase double-circuit line.

Sampling Rate Impact on Estimation of Untransposed Transmission Line Parameters Based on Fault Records

This paper highlights the sampling rate impact over an estimation method based on modal analysis techniques applied on untransposed three-phase transmission line. The analysed method represents a transmission system in the modal domain as three independent propagation modes that are modelled as three single-phase transmission lines using a suitable $$\pi $$ equivalent. The estimation procedure is carried out in the modal domain, without the explicit modelling of the phase mutual parameters, which means a significant simplification on the calculation process using the least-square solution method. Since the modal parameters are identified, the self- and mutual parameters can be calculated using the same modal transformation matrix during the line decoupling. The method estimation accuracy is evaluated for a range of sampling rate associated with the relays records.

Анализ и расчет пропускной способности воздушных линий электропередачи

Power transport is the most important component of an electric power system. Modernization and optimization of its operation, increase in capacity, as well as variation in connection circuitry with maintained or improved reliability is a crucial objective for the whole energy industry. The paper is about crea­ting a circuit-technical solution for a dual-circuit three-phase power transmission line whereby we define a new operating mode “with a split backup phase”. We herein describe conventional and non-conventional types of AC transmission such as overhead transmission lines, six-phase power lines, and flexible alternating current transmission systems (FACTS). We further analyze ways to improve the efficiency of overhead power transmission lines using structural and functional redundancy. A circuit-technical solution for a dual-circuit power transmission line with expanded operating modes is considered in detail. Possible operating modes of dual-circuit power lines are described. We also consider ways to increase the natural capacity of such lines. We have calculated the capacity of split backup phase lines and present the results of our calculations herein along with an analysis of such capacity in comparison to that of conventional transmission lines.

Calculation methodology of current distribution in traction networks of AC current

Several publications have been devoted to the development of traction power supply for alternating current [1, 2]. They set the task of considering the resistance of the external power supply system and power traction transformers when calculating the current distribution in traction networks. With all the merits of the existing methods for calculating these resistances, there are discrepancies in the published sources in determining the parameters of the equivalent circuit for the traction power supply system [3, 4, 5, 6]. In the present work, the authors propose a technique for calculating reduced to a voltage of 27.5 kV equivalent resistances of an external power supply system and a power traction transformer. An equivalent circuit for replacing the traction power supply system is substantiated, allowing to take into account the voltage drop on the overall resistance of the external power supply system from the traction currents of the considered and adjacent feeder zones, as well as transit currents flowing through the power lines. Using the method of symmetrical components it was obtained that when calculating the internal resistance of a traction substation consisting of the resistances of the longitudinal power supply line and the power traction transformer, it is necessary to use the calculated formulas obtained when taking into account the actual current distribution in the secondary (traction) winding of the power traction transformer. It is shown that the traction network equivalent circuit for the calculation of short-circuit currents, given in [1, 2], does not reflect the real current distribution relationships in traction networks. The main reason for the inconsistency of the scheme proposed by a number of experts with the existing traction power supply system is determined by an unjustified transition from an asymmetric system “three-phase transmission line - transformer - power supply system - single-phase traction network” to a single-line calculation scheme. When calculating the current distribution according to this scheme, there is no metallic connection of the track with one of the phases (more often phase C ) of the power traction transformer. The absence of this connection leads to the flow of traction currents between the district and traction substations, short-circuit current on the ground, which is not permissible.

Power Quality Conditioning in Railway Electrification: A Comparative Study

Electric transportation systems are a challenging load for three-phase transmission lines due to load variations, reactive power, imbalance, and harmonic pollution. Many power quality conditioners and compensation technologies have been developed to ensure compatibility with power systems. The most important ones are investigated, identifying parameters and performances for comparison, including evaluation of cost and size. A reference case is used for simulation, focusing on three-phase current intensity, current rate of rise, dc-link voltage, and dynamic response under various combinations of traction line load. The objective is to identify key characteristics supporting the selection of the appropriate compensation strategy for a new electrified railway system.

Estimation of zero sequence parameters of mutually coupled transmission lines from synchrophasor measurements

The authors consider the problem of estimating zero sequence parameters of a transmission line using synchrophasor data. When a set of three-phase transmission lines share, partial or complete, right of way, then their zero sequence models exhibit mutual coupling. As such the zero sequence parameters cannot be estimated by linear least squares or total least squares (TLS) technique which are the preferred methods when dealing with the positive sequence line parameter estimation problem. Further, method design has to factor the constraint of a sparse data set when dealing with zero sequence phasors. Therefore, the authors propose orthogonal distance regression approach for solving the zero sequence parameter estimation problem. This generalises the method of TLS to the non-linear parameter estimation problem considering noise in both the voltage and current synchrophasor measurements. Extensive case studies and comparative evaluations are presented to demonstrate the efficacy of the proposed approach.

Protection scheme for power transmission lines based on SVM and ANN considering the presence of non‐linear loads

The proliferation of non-linear loads in recent times has a strong bearing on power quality due to the presence of harmonics in the power system. Harmonics lead to erroneous measurement and malfunctioning of protective relays, thus reducing the efficacy of transmission line protection. With the aim of improving the dependability of the protection scheme under varying non-linear loading condition, the study presents a hybrid support vector machine (SVM), artificial neural network (ANN) and Kalman filter based algorithm using voltage harmonics for the protection of three-phase transmission line. The post-fault voltage signals are processed by a Kalman filter to estimate the harmonic components, which serve as feature vectors for performing the fault detection and classification by SVM and zone identification as well as the location by ANN. The harmonic information discriminates faults from disturbances based on variations in the fundamental component, to improve the selectivity and accuracy. Considering the stochastic nature of fault occurrence in power systems, the efficacy of the proposed scheme is validated using Monte Carlo simulation. The experimental results confirm the superiority of using voltage harmonics for improving the dependability of transmission line protection.

Modal decoupling of overhead transmission lines using real and constant matrices: Influence of the line length

The Clarke’s matrix is a well-known real and constant transformation matrix used for modal transformation in three-phase transmission lines modeling. Although modal analysis has been widely discussed in the technical literature on power system modeling, a new content is approached in this research proving that the approximation using an exact and constant modal transformation matrix depends on both the frequency-dependent parameters and transmission line’s length. As an important conclusion, the approach using the Clarke’s matrix leads to more accurate results considering long transmission lines. There are two methods for modal decoupling in power systems modeling. The first uses only a single constant and real transformation matrix during the entire modeling/simulation routine. The second uses the frequency-dependent transformation matrix for parameters decoupling into the propagation modes and the Clarke’s matrix for mode-to-phase transformation of voltage and current values during simulations. The accuracy of these two modeling/simulation processes are evaluated, in the time and frequency domains, based on results obtained from a reference routine that employs the exact frequency-dependent matrix in modal transformations and numerical transforms for simulation in the time domain. The proposed analysis proves that the accuracy of both methods varies with the line length during electromagnetic transient simulations that leads to peak errors up to approximately 10%. The influence of the line length in modal analysis techniques was not approached in previous references on power system modeling, which represents the original contribution of this paper.