Double-circuit Transmission Line Research Articles

A ground fault location algorithm in double‐circuit transmission lines with T‐off connection to an industrial microgrid by using current and voltage phasors information of a single terminal

AbstractThe paper presents a ground fault location algorithm (GFLA) in double‐circuit transmission lines (DCTL) with a T‐off connection to an industrial microgrid (IMG) containing electric arc furnaces (EAF), renewable distributed generations (RDG), and static VAR compensator (SVC). The design presented utilizes the information on the current and voltage phasors of one side of the transmission lines (TL) during the fault period, and there is no need for the availability of information on the type of faulty phase(s) and even the faulty section. To find the exact location of the fault in this design, the voltage phasor equations governing the fault point in positive, negative, and zero‐sequence (PNZS) domains, the zero‐sequence current (ZSC) equation of the fault point, and the boundary condition equation of the fault point have been used. The simulation system is implemented in Simulink/MATLAB using accurate modelling of all network components. The algorithm has been tested and evaluated in different fault conditions, including various locations, phase types, phase‐to‐ground connection resistance, occurrence time, and microgrid (MG) operation modes. The successful results of various tests of the proposed design as well as the analysis of various sensitivities confirm the satisfying performance of the suggested algorithm.

Highly efficient relay triggering circuit for fault detection during Power swings

This paper introduces a Discrete Wavelet Transform based very simple and fast acting algorithm with multi-resolution analysis to sense all types of faults in presence of power swings using current signal analyzation. The algorithm confirms very quick and efficient detection of various fault types in the first signal decomposition level of signal. The novelty of proposed algorithm lies in use of special type of Battle Lemarie mother wavelet having an advantage of perfect symmetry ensuring decomposition into B-Spline or same order polynomials capturing excellent speed and time-frequency localization of signal. The algorithm is tested for different fault parameters such as fault resistance, fault distance and time of initiation of faults considering EHV double circuit transmission line network and IEEE 9 Bus system developed in MATLAB environment. The proposed algorithm is capable of detecting all types of faults consistently within minimum time of 0.001 sec.

Simulation Analysis of Electric Field on the Body Surface of Personnel Engaged in Interphase Live Working on 750 kV Double Circuit Transmission Lines on the Same Tower

This article focuses on the assistance of electric lifting devices for phase-to-phase live working. Taking a typical 750 kV double circuit vertical arrangement line on the same tower as the research object, a three-dimensional simulation model of a real tower conductor simulated human is established. The field strength on the human body surface is calculated and analyzed during the process of operators entering the equipotential (conductor) while riding the electric lifting device in order to determine the risk points of the operation and determine the safety protection measures for the human body. Through simulation, it is found that when simulating human entry (exit) and phase-down operations, the human body is located at different distances of 0.4 m-1.5 m directly below the conductor. When not wearing shielding clothing, the maximum field strength of the human head is much greater than the allowable value. If using shielding clothing with a shielding efficiency of 60 dB for safety protection, the surface field strength inside the worker’s clothing can be reduced to 2.25 kV/m, meeting the requirements of live working. Operators should pay attention to the electric field protection at each phase wire when using an electric lifting device to enter (exit) the interphase wire. Equipotential operators must wear a complete set of shielding clothing for 750 kV live working.

Flashover pattern analysis for 275 kV double circuit transmission lines during direct lightning strikes

Lightning overvoltage causes outages of transmission lines (TLs) in tropical countries. Identifying and analyzing the key factors responsible for tripping the lines can improve the performance of the lines. In this work, the flashover patterns due to direct lightning strikes on 275 kV double circuit TLs and towers in Malaysia was evaluated with Electromagnetic Transient Program (EMTP-RV). Three parameters that include lightning current magnitude, power frequency angle and tower footing resistance were analyzed on the line performance during direct lightning strikes. The simulated results found that two key parameters, lightning current at 270 kA and footing resistance at 50 Ω, reveal the highest impact on the insulator flashover. This finding was also verified from multivariate analysis results which is rarely found in the previous works in this field. As a key contribution in this work and in validation to the model, the simulated fault waveform patterns and voltage magnitudes were compared with the actual site data obtained from six different locations in Peninsular Malaysia. The analyzed results show a similar waveform pattern with an overall average voltage magnitude difference of 6.0 % before and after fault. The model is useful to electric utilities for analyzing transient performance of TLs.

Comparative Analysis of 500 kV Double-Circuit Transmission Line Electric Field Intensity: Ethiopian Lines Compliance with ICNIRP

Comparative Analysis of 500 kV Double-Circuit Transmission Line Electric Field Intensity: Ethiopian Lines Compliance with ICNIRP

Impact Study of the Hetauda-Dhalkewar-Inaruwa Transmission Line on the Operation of Integrated Nepal Power System

Despite Nepal’s abundant hydroelectric resources, a substantial disparity exists between its electricity supply and demand. This discrepancy is exacerbated by the absence of high-voltage transmission lines, hindering efficient power evacuation from a handful of generating plants. This not only incurs financial losses for the utility but also compromises the reliability of the power supply. A prime example is the protracted delay in the construction of the 576 KM long Hetauda-Dhalkebar-Inaruwa 400kV double-circuit Transmission Line, primarily due to challenges posed by local residents unwilling to relinquish their land.The Integrated Nepal Power System (INPS) heavily relies on power generation concentrated in the central mid-hills region. The construction of the Hetauda-Dhalkebar-Inaruwa (HDITL) 400kV double-circuit Transmission Line is crucial for routing power to industrialize these areas, potentially bolstering the national GDP and generating employment opportunities. Furthermore, it is essential to connect the current hydropower output of around 2300 MW to the INPS system via a high-voltage transmission line to maximize its utilization. The HDITL project not only reduces line losses but also enhances grid stability. It facilitates energy export and direct transmission of high-generation power, such as the 456 MW from Upper Tamakoshi, thus saving approximately 400 MW of power and preventing losses for both the Government of Nepal (GoN) and the Nepal Electricity Authority. This research not only calculates the reduction in power and energy losses with the commissioning of HDITL but also assesses its monetary benefits. Utilizing INPS data and Digsilent Power Factory 15.1 for power flow analysis, the study estimates that HDITL can prevent a power loss of about 26.276 MW. Furthermore, it demonstrates that HDITL significantly improves the total generation power factor in INPS, from 0.88 to 0.99, and enhances the voltage profile, underscoring its critical role in Nepal’s energy infrastructure development.

Statistical switching method to establish the minimal requirements of insulation coordination in double-circuit transmission lines

Statistical switching method to establish the minimal requirements of insulation coordination in double-circuit transmission lines

Fault location of untransposed double-circuit transmission lines based on an improved Karrenbauer matrix and the QPSO algorithm

Some double-circuit transmission lines are untransposed, which results in complex coupling relations between the parameters of the transmission lines. If the traditional modal transformation matrix is directly used to decouple the parameters, it can lead to large errors in the decoupled modal parameter, errors which will be amplified in the fault location equation. Consequently, it makes the fault location results of the untransposed double-circuit transmission lines less accurate. Therefore, a new modal transformation method is needed to decouple the parameter matrix of untransposed double-circuit transmission lines and realize the fault location according to the decoupled modal parameter. By improving the basis of the Karrenbauer matrix, a modal transformation matrix suitable for decoupling parameters of untransposed double-circuit transmission lines is obtained. To address the difficulties in solving the fault location equation of untransposed double-circuit transmission lines, a new fault location method based on an improved Karrenbauer matrix and the quantum-behaved particle swarm optimization (QPSO) algorithm is proposed. Firstly, the line parameter matrix is decomposed into identical and inverse sequence components using the identical-inverse sequence component transformation. The Karrenbauer matrix is then transformed to obtain the improved Karrenbauer matrix for untransposed double-circuit transmission lines and applied to identical and inverse sequence components to solve the decoupled modal parameter. Secondly, based on the principle that voltage magnitudes at both ends are equal, the fault location equation is expressed using sequence components at each end, and the QPSO algorithm is introduced to solve the equation. Finally, the feasibility and accuracy of the proposed method are verified by PSCAD simulation. The simulation results fully demonstrate that the innovative improvement on the basis of the traditional modal transformation matrix in this paper can realize the modal transformation of the complex coupling parameters of the untransposed double-circuit transmission lines. It causes almost no errors in the decoupling process. The QPSO algorithm can also solve the fault location equation more accurately. The new fault location method can realize the accurate fault location of untransposed double-circuit transmission lines.

Transient stability analysis of dual excited synchronous generator with excitation control

A Dual Excited Synchronous Generator (DESG) has two field windings. The stability enhancement of the power system can be achieved with felicitous control of these two field windings independently. Most of the work covered in the literature is on the stability analysis of DESG and the independent control of field windings. The independent control allows different amounts of current in field windings, which leads to unequal field losses and uneven rotor heating. The drawback is minimized in this work by keeping a predetermined angle between the excitation voltages. A simple excitation control similar to IEEE static exciter, regulates the d-axis and q-axis components of voltage, termed as Excitation type-1 (ET1), is presented in this paper. Also, the excitation system presented in the literature termed in this paper as Excitation type-2 (ET2) for comparison. The modified versions of both ET1 and ET2 are also presented to get overall improvement after a disturbance. The DESG connected to an infinite bus through a double-circuit transmission line is the system under study. Transient stability analysis of DESG with both types of exciters as well as Conventional Synchronous Generator for several disturbances in the system are presented, and also the results are compared.

A protocol for selecting viable transmission line arrester for optimal lightning protection

Direct lightning strikes on overhead lines and towers causes power system outages. Optimal surge arrester placement is a practical and economical protection technique. From research trends, three types of transmission line arresters are in practice: Non-Gapped Line Arrester (NGLA), Externally Gapped Line Arrester (EGLA) and Multi Chamber Insulator Arrester (MCIA). This study proposed a simplified guide for selecting the most suitable line arrester considering the placement configurations, double circuit outage prevention and energy capabilities. Electromagnetic Transient Program was implemented to analyze back flashover performance of a typical 275 kV double circuit transmission line in Malaysia. Critical flashover parameters considered are lightning current magnitude, tower footing resistance, and power frequency angle. Analyzed results from the three arresters found that installing four arresters, two per circuit, at the lower and upper phases respectively, is the most optimal and universal double outage mitigation technique. Energy comparison reveals that MCIA discharges 54% and 44% less energy than NGLA and EGLA respectively. Also, from 132 kV system results, MCIA discharges 74% and 22% lesser energy respectively. From further validation of the simulation model, NGLA discharged 23.8% more energy than EGLA from experimental results. The proposed guide is applicable to double circuit lines below 275 kV.

Reliable protection for static synchronous series compensated double-circuit transmission lines based on positive sequence active power calculations using PMUs

Static Synchronous Series Compensator (SSSC) allows dynamic control capabilities of transmitted power. Unfortunately, inserting SSSC in transmission lines (TLs) disturbs impedance-based distance relays as their directionality and reachability are affected by overreaching or underreaching. This paper proposes an approach for protecting double-circuit TLs compensated with SSSC. It relies on the centralized wide-area protection architecture to calculate a proposed driven index: the rate of change of positive sequence active power difference. Phasor measurement units (PMUs) at TL ends estimate voltage and current phasors to calculate the positive sequence active power at TL ends and send them to the system protection center that evaluates the index and gives the trip decision or not. Ensuring the sensitivity, dependability, and security of the approach is essential. So, the overall scheme integrates two other algorithms. One is based on the polarities of the incremental power at both ends to determine whether the fault is internal or external. The other evaluates the phase angle of the integrated impedance to deactivate the power swing-blocking function for fault detection. The scheme's effectiveness is validated comprehensively through extensive simulation tests for fault and system conditions. The results show that the proposed approach is fast, secure, selective, and reliable.

Unsynchronized Parameter-Free Fault Location for Two or Three Terminal Double-Circuit Transmission Lines Sharing the Same Tower via Unscented Kalman Filter

This paper proposes a novel phasor domain fault location method for two or three terminal double-circuit transmission lines sharing the same tower without requiring line parameters. First, the models of the two and three terminal double-circuit lines with faults are derived. The line models fully consider the mutual coupling between the two line circuits, distributed line parameters, asymmetry of line structures, and extensive fault types. Through the modeling procedure, the fault location, line parameters, unsynchronized phase angle, fault resistance and other internal states of the line are introduced as unknown variables, resulting in a highly nonlinear problem. Afterwards, the line model is solved via the state estimation algorithm. Compared to the existing least square type algorithms such as Gauss-Newton and Levenberg Marquardt methods, the proposed Unscented Kalman Filter based algorithm greatly improves the convergence region. Compared to the existing parameter-free fault location method on double-circuit transmission lines, the proposed method more accurately presents the physical laws of the line and is compatible with common or split bus configurations. The proposed method is verified via numerous simulation experiments, proving that it can accurately locate faults for different fault resistances, locations and types. The method is also validated via field data experiments.

Simulation of photovoltaic station interfacing scada within transmission line

In this paper, a developed simulation of a photovoltaic (PV) station that includes a PV module, a grid-connected inverter, a maximum power point tracking (MPPT) system, and a DC link capacitor was discussed. The MPPT uses a proportional integral derivative (PID) incremental conductance controller. Due to make it simple to control and monitor the PV station, Simulink dashboard is used to develop an interface that resembles a supervisory control and data acquisition (SCADA) system. Then the faults circumstances were simulated on one of the circuits of the double circuit transmission line using the faults combo box that is accessible in the interface. Then the cases were developed to examine the impact of various faults on the operation and control of the solar station. The developed cases namely normal circumstance, single-phase to ground fault circumstance, double-phase fault circumstance, and three-phase to ground fault circumstance, respectively. Three-phase voltage and current at given fault conditions have been measured to control voltage sag and swell. The active and reactive power are also measured due to obtain that they are injected or absorbed the power from and to the transmission line and maintain toward their setpoint values as indications while the faults occurred.

Multi-Phase Power System Simulation

Abstract: Six Phase Transmission System has the capacity to increase the transmission capacity by 1.732 times the existing Three Phase System. It is possible to convert existing Three Phase Double circuit transmission line into compact Six Phase transmission line within the existing Right-of-way. Forecasting the demand and supply of Electrical energy gives the alternative solution is Six Phase Transmission system in addition to its several advantages like reduced phase voltage, less corona, declined magnetic field etc. This paper presents the study and analysis of design of transformer for six phase system. Comparison by system count per unit use MATLAB and PSCAD/ EMTDC simulation implemented for both system. Analysis of data carried out for parameters as value phase difference, voltage, current and power in transmission line. Apart from that assessment choosing the best transformer design for six phase system also implemented. From the analysis data performed found line system six phase have successfully produced ascendant as many as 73% in the division transmission line over system double three phase circuit. Apart from obtain that the best connection six phase system to acquire stated ascendant is delta Star delta inverted Star connection and diametrical connection

Single fuzzy inference based fault detection and classification protection scheme for different types of short circuit faults on double circuit transmission lines

ABSTRACT An intelligent protection scheme based on the single fuzzy inference system and discrete Fourier transform is proposed for the faulty phase detection and classification of faults on the mutually coupled double circuit transmission lines. This proposed protection technique uses the magnitude of the pre-processed current information of the sending end bus only. This is implemented in the MATLAB/Simulink environment on a 400 kV, 50 Hz, and 300 km double circuit power system model. The efficacy of the proposed scheme has been tested by performing a wide range of simulation studies concerning different types of faults (common short circuit faults, cross-country and evolving faults, and high impedance faults) and typical fault scenarios (current transformer saturation, noisy environment, and fault during power swing conditions) with variations in different fault parameters and operating conditions. The results presented confirm that the proposed method detects/classifies all the faults within one cycle time and is reliable with a detection/classification accuracy of 99.75%. It is immune to variations in fault parameters, and different operating conditions, and is not affected by the zero sequence mutual impedance. It does not require any training and communication link. Further, the performance is also appraised with other training-based protection schemes.

A current-based algorithm for one-end fault location in series capacitor compensated double-circuit transmission lines

Fault location is essential in series capacitor compensated double-circuit transmission lines regarding their capacity in transferring large amounts of power. The main challenge in the fault location of these lines is the nonlinear behavior of the metal-oxide varistor (MOV) in protecting the series capacitor against overvoltage during faults. In this paper, considering the MOV model and zero-sequence mutual coupling impedance between the two circuits, a new algorithm is presented for the location of single-line-to-ground faults, using currents measured at one end of the line. In this algorithm, first, a fault location is obtained for each data window, and then the exact location is calculated using statistical techniques. The proposed algorithm is independent of the measured voltages, and as a result, no error in the voltage measurement affects its accuracy. In addition, needing no telecommunication channel to access the data of the remote substation leads to reliability increasing and cost reductions. Not requiring pre-fault data is another advantage of the algorithm. The results indicate that the algorithm is independent of fault location and resistance, fault occurrence time, load conditions, and compensation level. In addition, the fault location error in all scenarios is within the standard range.

A distance Protection/Fault location algorithm for Double-Circuit transmission lines with asymmetrical circuits during Cross-Country faults

The impedance-measuring elements and fault locators in distance relays suffer from measuring the correct fault impedance and fault location when facing cross-country faults (CCFs). During such atypical faults, this paper proposes a distance protection along with a fault location algorithm for double-circuit lines with asymmetrical circuits. This is fulfilled through instantaneous fault-branch currents innovatively derived from the line six-phase circuit model analysis on a time-domain basis. The currents derived lead to the relations that are mathematically linear combinations of designated vectors. This makes the possibility of establishing vector-input adaptive linear combiners (VI-ALC) in accordance with the relations derived. Being fed from the vectors of instantaneous measurements at the relaying side, the VI-ALCs with a distinctive capability of online training would swiftly give an accurate estimation of the fault distances during CCFs. The estimations are exploited in a logical procedure for both of the distance protection and fault location functions, taking account of different position status of the CCFs’ comprising LG faults. The proposed algorithm is feasibly implementable and is independent of the system configuration. It operates robustly in high-ground resistance and noisy conditions. Through extensive simulation studies in PSCAD/EMTDC, performance of the proposed algorithm would be investigated and verified in a variety of fault scenarios.

Reliable Protection for Static Synchronous Series Compensated Double-Circuit Transmission Lines Based on Positive Sequence Active Power Calculations Using Pmus

Reliable Protection for Static Synchronous Series Compensated Double-Circuit Transmission Lines Based on Positive Sequence Active Power Calculations Using Pmus

Comprehensive research on hybrid energy storage strategies of park microgrids with optical storage and DC microgrids

The multi-circuit coupling transmission mode is an inevitable trend of power grid construction, mainly with partially coupled multi-circuit lines. Affected by the local coupling between lines, the existing fault location methods have large errors. To this end, fault analysis and fault location methods are carried out on partially coupled double-circuit transmission lines. According to the structure and characteristics of the partially coupled double-circuit transmission line on the same tower, the voltage and current interface equations at the coupling demarcation point of the partially coupled double-circuit transmission line are established using line decoupling theory. On this basis, a time-domain analysis model of fault location for each coupling section is constructed, and a time-domain method for fault location of partially coupled double-circuit transmission lines is proposed. Finally, the electromagnetic transient simulation software is used to construct a partially coupled double-circuit transmission line model on the same tower, and a comprehensive simulation verification is performed. The results show that the proposed method has high accuracy.

A novel line parameter adaptive phasor domain fault location method for double-circuit transmission lines

• Accurate phasor domain fault location for double-circuit transmission line. • Fault location without acquiring information of line parameters. • Uniqueness and convergence of the fault location equation solution. Phasor domain methods had been commonly used in power transmission line fault location. To improve the accuracy and line parameter adaptive ability of phasor domain fault location, this paper studies a two-terminal phasor domain line parameter adaptive fault location method. First, this paper analyses the convergence issue of original multi-dimensional non-linear fault location equations. Then, by regarding the four complexes consist of fault distance and line parameters as the new unknowns and thereby supplementing a constraint equation about the new unknowns, a quadratic fault location equation set is reconstructed. Furthermore, it is mathematically proven that the four new unknowns are all within the first quadrant. Therefore, the elements in the Jacobian matrix of the reconstructed equation set are all proven to be of symbolic invariance within the solution space. Thus, by using Newton-Raphson method and setting the initial iteration value of the four unknowns to any complexes within the first quadrant, the iteration solution of the reconstructed equation set will converge to the true solution. Finally, electro-magnetic fault simulations are used to evaluate the proposed method. The test results demonstrate that the proposed method is able to guarantee fault location accuracy under different circumstances without knowing line parameters.