Double-circuit Transmission Line Research Articles

A single-end directional relaying scheme for double-circuit transmission line using fuzzy expert system

The faults occurring in different sections are difficult to identify using the traditional techniques. This paper investigates a fuzzy expert system for directional relaying, classification, and location of faults in double-circuit transmission lines. The current magnitudes measured at only one terminal of the double-circuit transmission line are used to compute discreet Fourier coefficients. Thus, this scheme does not involve any communication channel. The presented fuzzy expert system is achieved from the structure of MAMDANI system in LabVIEW software. Test case studies show the effectiveness of the presented scheme. The simulation results attest that the directional relaying, classification, and location estimation is very accurate. This scheme is adaptive to the change of fault location, fault resistance, fault inception angle, and fault type.

Improved Distance Relaying for Double-Circuit Lines Using Adaptive Neuro-Fuzzy Inference System

Utilizing double-circuit lines may represent a challenge for distance relaying functions owing to the significant impacts of the mutual coupling among the adjacent conductors. This paper proposes a new adaptive distance relaying scheme for double-circuit transmission lines using fuzzy logic tuning. The scheme depends on two basic steps. First, the impacts of the mutual coupling of the adjacent conductors on the accuracy of the distance relaying core are minimized based on the decoupling feature of modal transformation. Then, a dedicated online intelligent tuning mechanism is utilized to precisely improve the relay reach. The adaptive neuro-fuzzy inference system is employed to realize an optimum design of the aimed tuning mechanism. A thorough investigation of the proposed scheme is performed utilizing a detailed modeling of a typical 400-kV interconnection system with both single- and double-circuit line segments. The electromagnetic transient program (ATP-EMTP) is employed for modeling the considered power system, whereas the protection scheme is constructed and tested using MATLAB. Finally, the performance of the proposed relaying scheme is investigated under different load conditions, various fault types and fault locations to visualize its efficacy precisely. As compared with conventional distance relaying core, the proposed adaptive distance scheme has a precise fault distance estimation with a reach error less than 6% of the total line length. Accordingly, a corrected declaration of the faulted zone is realized along the entire range of the protected line despite the added fault resistance, loading condition and fault type.

Fault location on double–circuit transmission lines by phase correction of fault recorder signals without accurate time synchronization

Fault recorders (FRs) are widely adopted to display signal waveforms. However, accurate time synchronization may not be available to the FRs mounted at substations. By phase correction of the phasors recorded by the FRs at the remote terminal, a novel fault location (FL) scheme for double circuit lines is proposed. In the scheme, six-sequence component transform (SCT) is firstly used to decouple the line. A corrected phase difference is introduced into the phases of the co-rotating positive sequence (CPS) voltage and current phasors at the remote terminal prior to the fault. Based on the distributed parameter model, the corrected phase is then determined by calculating the CPS voltage phasors along the line using the phasors acquired by the FRs at both terminals. Finally, considering the reverse positive sequence (RPS) circuit of the line, the corrected RPS phasors at both terminals after the fault are utilized to construct the voltage absolute difference function. By searching the minimum value of the function, the FL can be estimated. A double circuit line is established by PSCAD/EMTDC. Various simulations demonstrate that the proposed scheme is barely affected by fault type, resistance, inception angle, distance, noise, asynchronous phase and circuit breaker operation.

Adaptive Autoreclosing Scheme for Line-to-Line Nongrounded Faults on Double-Circuit Transmission Lines Based on Phase-to-Phase Reactive Power

Double-circuit transmission lines play a very important role in electric power transmission. When a line-to-line nongrounded fault occurs on double-circuit transmission lines, for traditional tripping and reclosing methods, tripping of all six phases may cause power system instability, and fixed time autoreclosing may reclose the double-circuit transmission lines to a nonextinguished fault. In this paper, a novel tripping strategy is proposed; when a line-to-line nongrounded fault occurs, some part of the electric power can be transmitted after tripping, and many kinds of nongrounded faults can be equivalent to a single-phase to ground fault. Furthermore, reactive power characteristics are adopted to determine the fault extinction. Finally, an adaptive autoreclosing scheme for line-to-line nongrounded faults on double-circuit transmission lines based on phase-to-phase reactive power is proposed. The accuracy and feasibility of the propose method are verified by relevant simulation experiments, and multiple operation conditions are considered.

Research on the Measurement of Zero Sequential Equivalence Impedance of Double-circuit Transmission Lines

The measurement of transmission line parameters is often affected by adjacent lines, especially the measurement of zero-sequence impedance parameters is affected by mutual inductance between lines, thus affecting the measurement results. This paper establishes the double-circuit transmission line model to verify the change of zero-sequence impedance parameters of transmission lines when the spatial layout of double-circuit transmission line in different interference signal carriers and the size of interference signal are different. The variation law of zero-sequence impedance parameters of transmission line affected by interference lines is summarized. It provides a reference for the subsequent setting of relay protection devices for transmission lines.

New Fault-Location Algorithm for Series-Compensated Double-Circuit Transmission Line

This paper proposes a new fault location algorithm to accurately locate the faults of series-compensated double-circuit transmission line and improve the stability of power system operation, which is not affected by fault types. The proposed algorithm is based on asynchronous voltage and current at both ends of the line, the pre-fault voltage and current are used to synchronize time. The six-sequence component transformation is introduced, and with the help of the phase-sequence selection rule, the proposed algorithm eliminates the non-linear impedance of metal oxide varistor (MOV). Simultaneously, to confirm the robustness of the algorithm, different fault types, different fault initial angles and different fault resistances are taken into account in the system simulation. Not only that, the influence of series capacitors (SCs) installation positions, line parameter errors, different sampling rates and measurement errors are also tested. In general, the proposed fault-location algorithm has excellent performance. PSCAD/EMTDC and MATLAB are used in simulation studies, the results show that the maximum estimated error of fault-location does not exceed 1.8631%.

Optimization of 400kv Transmission Line Towers

Paper Setup Electric power plays an important role in the life of the community and the development of various sectors of economy. Developing countries like India therefore give a high priority to power development programmes. Wind pressure on conductor, insulator and ground wire and the wind load on the tower has been arrived based on IS 802 – 1995 by taking into consideration of the following factors like average height of the conductor above the ground, drag coefficient of conductor, insulator and ground wire, position of different panels, total surface area of members in each panels, height from C.G to the ground level. Different loading conditions like Reliability condition, safety, security and anti cascading condition will be considered in different aspects which will be used in analysis and design. This project deals with “optimization of 400KV double circuit transmission line towers” in which the design can be executed by using STAAD PRO. The design and optimization of the tower can be carried out by altering the tower base width. By altering the base width of the tower, the corresponding members, bracing sizes and material properties of the members are being changed for analyzing the economical section. Depending upon the modified tower base width, the member and bracing sizes are suitably provided for different effective base width trials so as finalize the output of economical modified base width tower. The best optimized tower can be determined and recommended for safety and economy of steel

Adaptive neuro fuzzy inference system-based fault location technique in double circuit transmission line against simultaneous faults

The conventional distance protection technique malfunctions in case of a double circuit transmission line during simultaneous faulty conditions. To mitigate this problem, an adaptive neuro fuzzy inference system with different membership functions and discrete Fourier transform-based technique has been presented in this paper. A 400 kV, 50 Hz double circuit transmission line is simulated in PSCAD software, while the fault location technique is implemented in MATLAB software. The fundamental components of phase voltages and phase currents are fed as inputs to the proposed technique. The proposed technique is investigated under various fault inception angles and fault locations as well as all possible fault cases including shunt and series faults. Its effectiveness is checked through PSCAD simulations, and the results prove that it can be employed in the simultaneous fault locating of double circuit transmission line. The simulation study with mathematical validation promises the validation of the technique for all fault cases.

A Novel Protection Algorithm for Phase to Phase Faults in Double Circuit Transmission Lines

The selection of robots used for industry purpose is a crucial practice where various parameters have to be considered during appropriate selection process. The decision strategy of robot selection has a potential research direction to justify the necessity of industrial needs. We have compared three different mathematical models and selected the best method for choosing the a targeted application. In addition to the mathematical methodologies applied here, the performance characteristics for selecting the robot is examined by assessment of statistical errors namely Mean Square Error (MSE), Root Mean Square Error (RMSE), and R-Squared Error (RSE)

Development of the wave method of calculation operational parameters of a double-circuit power transmission line with known values of output voltages and currents at the end of the line

Electrical energy from the place of its generation is transmitted to consumers of various capacities. The distance from the source of electrical energy to the consumer can vary from several meters to several thousand kilometers. In this regard, the accurate determination of the operating parameters of the power transmission line (PTL) is a mandatory and necessary condition for the PTL normal functioning. In the current-carrying parts of the double-circuit PTL there are six incident and six reflected waves of the electromagnetic field. They determine voltages and currents. A scheme is proposed for the distribution of these waves along linear wires of a homogeneous section of a double-circuit PTL. This scheme shows that the current-carrying parts of the adjacent wires have a significant impact on voltages and currents in one wire. This scheme illustrates the distribution of the amplitude values of electromagnetic field waves, defined as the integration constant. Using the integration constants, the propagation constants of electromagnetic waves along the linear wires of the PTL and the corresponding wave impedances, one can obtain the amplitude values of the incident and reflected waves at any point of the double- circuit PTL, and hence the currents and voltages in the double-circuit PTL. The article presents a method for determining the currents and voltages in a double-circuit PTL according to the load. The proposed method will allow determining the qualitative and quantitative indicators of electrical energy (induced voltage) appearing from each wire separately and provide the possibility of their elimination, which will improve the quality of electrical energy.

An Enhanced Fuzzy Rule Based Protection Scheme for TCSC Compensated Double Circuit Transmission System

ABSTRACT This paper introduces a fault detection and faulty phase selection technique for a double-circuit transmission line with thyristor-controlled series capacitor (TCSC). In a transmission system, the nonlinear operation of TCSC during switching modes distorted the voltage and current signals. The effect is more if the fault occurred at zero fault inception angle. An advanced protection approach to overcome these issues based on dynamic phasor estimation of current from local measurements is proposed in this work. The maximum transient component obtained from three phases is used as an index to accomplish the detection task. However, due to the nonlinear operation of different accessories connected to the controller unit such as metal oxide varistor (MOV) and thyristor circuit, identification of the exact faulty phase is still a challenge. To mitigate this issue, fuzzy decision-based rules are framed so that identification of exact faulty phases is possible. For validation, the method is tested on a 400-kV, 50-Hz power system model developed using EMTDC/PSCAD. Results obtained from simulation indicate that the method is reliable and a secure unit protection can be effectively provided to a double-circuit transmission system equipped with TCSC.

Fault location estimation for series-compensated double-circuit transmission line using EWT and weighted RVFLN

In this paper, empirical Wavelet transform (EWT), Hilbert transform (HT) and weighted random vector functional link network (WRVFLN) are integrated for fault detection, classification, and location estimation in a series capacitor compensated double circuit transmission line (SCCDCTL). The full cycle current signals from the point of fault inception are decomposed using EWT to extract three band-limited modes (BLMs). The four efficacious instantaneous features namely energy, Shannon entropy, the standard deviation of the magnitude, and crest factor are computed from the Hilbert transformed array of the BLMs to construct the feature vector. A diagonal matrix W is computed from the zero sequence current of original six current signals as a weighting factor to categorize the ground fault accurately. Numerous faults are generated with a wide variation of the system conditions such as fault resistance, fault inception angle, fault distance, percentage compensation level, source impedance, line parameters, load angle, and inter-circuit fault in MATLAB/Simulink environments. An efficient WRVFLN computational intelligence technique is proposed to recognize and estimate the location of the faults by taking the extracted suitable feature vector with weight factor as an input. The performances of WRVFLN are compared with the recently developed advanced classifiers such as least-square support vector machine (LSSVM) and extreme learning machine (ELM) in the MATLAB interface. The lesser computational complexity, faster learning speed, superior classification accuracy, accurate fault location estimation, and short event detection time prove that the proposed EWTHT–WRVFLN method can be implemented in the real power system for online fault diagnosis. Finally, the developed system architecture is implemented on the reconfigurable digital field programmable gate array (FPGA) in ISE design suite 14.5 environments to verify the cogency of the proposed method in real-time. The feasibility of the proposed method is tested and validated by using the fast FPGA digital circuitry in a loop.

Fault location estimation for series-compensated double-circuit transmission line using parameter optimized variational mode decomposition and weighted P-norm random vector functional link network

In this paper, both the proposed parameter optimized variational mode decomposition (POVMD) and weighted P-norm random vector functional link network (WPRVFLN) are integrated for fault detection, location estimation, and classification in a series capacitor compensated double circuit transmission line (SCCDCTL). The required number of decomposition is determined from the magnitude spectrum of full-cycle current signals from the point of fault inception. An entropy index is used to obtain the optimum value of data-fidelity factor for extracting the most suitable band-limited intrinsic mode functions (BLIMFs). The four efficacious features namely standard deviation of the magnitude, energy, Renyi entropy and crest factor are computed from the Hilbert transformed array of the BLIMFs to construct the feature vector. A diagonal matrix W is computed based on zero sequence current of the original current signals as a weighting factor to categorize the ground fault accurately. Numerous faults are generated with a wide variation of the system conditions in MATLAB/Simulink simulation environment. An efficient WPRVFLN computational intelligence technique is proposed to recognize the fault by taking the extracted feature vector with weight factor, and its performances are compared with the recently developed classifiers in the MATLAB interface. The lesser computational complexity, faster learning speed, superior fault location estimation accuracy, and short event detection time prove that the proposed POVMD–WPRVFLN method can be implemented in the real power system for online fault recognition. Finally, the feasibility of the proposed method is tested and validated by using the fast FPGA digital circuitry in a loop.

New Algorithm for Protection of Double Circuit Transmission Lines Using Modal Currents

This paper presents a new protection algorithm for double circuit transmission lines using the sum of ratios of modal currents. Relay-operating characteristics is proposed using the complex ratio of modal currents. The proposed algorithm estimates modal domain line parameters and identifies the faulty phases for single pole-tripping applications even during inter-circuit faults. The scheme is sensitive to high resistance internal faults and also detects internal faults with outfeed. The proposed scheme is immune to mutual coupling and is found robust to uncertainties in parameter estimation due to measurement inaccuracies. The scheme is tested for its effectiveness to deal with current transformer saturation and synchronisation error. The scheme protects series compensated double circuit transmission lines even in the presence of current inversion. Exhaustive case studies in electromagnetic transient program (EMTP)/alternate transient program are performed on 400 kV, 300 km, double circuit transmission lines and the proposed protection algorithm is implemented in MATLAB. The results confirm the superiority of the proposed scheme.

Research on Windage Yaw Flashovers of Transmission Lines under Wind and Rain Conditions

Windage yaw flashovers under strong wind and rain conditions leave a negative impact on the safe operation of transmission lines. However, the mechanism behind this is not well known yet. Therefore, this paper proposes a systematic method, including three basic parts described as simulation of wind and rain loads, calculation of windage yaw, and flashover analysis, to analyze windage yaw flashovers of transmission lines. The YanMeng-particle swarm optimization (YanMeng-PSO) algorithm is proposed to enhance the simulation accuracy. Unlike the conventional approach, the windage yaw status of conductors and insulator strings is dynamically described with key nodes and the breakdown voltage of their clearances rather than windage yaw angle. Furthermore, in the second part, a new method named key-node method (KNM) is proposed to calculate the conductors’ windage yaw. Moreover, the rain effect is also considered in this paper. This paper then presents a case study on a 110 kV double-circuit transmission line section that suffered severe collapse when the typhoon Rammasun landed in Hainan island. Particular focus was placed on the windage yaw flashover before the structural failure of the transmission line. The results validated the significant rain effect and found that conductors/ground suffer more severe windage yaw flashover than insulator strings. Finally, constructive solutions such as interphase spacers, reasonable conductor arrangement in the design phase, and regular measurements and adjustments of conductor sag in the maintenance phase are proposed to improve the design of transmission lines to enhance their capacity against windage yaw flashovers.

Accurate fault location algorithm for shunt-compensated double circuit transmission lines using single end data

This paper introduces an accurate fault location algorithm for double-circuit transmission lines compensated by Static Var Compensator (SVC). The proposed algorithm is based on the negative-sequence circuit of the transmission system and it depends only on the current data available from one end of the line. Since only magnitudes of current signals are required, there is no need for data synchronization. The proposed technique uses the COMTRADE fault files available from digital distance relays and it can effectively locate the all types of unbalanced faults, regardless the high fault resistance, effect of mutual coupling and SVC current injection information. As one formula can be used for all types of fault, classification of fault types and phase selection are not required. The shunt capacitances of the line are considered by utilizing the distributed parameters model of the transmission lines. The proposed algorithm is rigorously investigated for various fault scenarios in SVC compensated transmission system. The simulation cases in the MATLAB environment verifies that the proposed scheme has excellent performance. Test results are compared with a conventional fault location technique to illustrate the accuracy of the proposed algorithm.

Fault location identification of double circuit transmission line using discrete wavelet transform

<span lang="EN-GB">The importance of supplying undisturbed electricity keep increasing due to modernization and lifestyle. Any disturbance in the power system may lead to discontinuation and degradation in the power quality. Therefore, detecting fault, fault type and fault location is a major issue in power transmission system in order to ensure reliable power delivery system. This paper will compare two prominent methods to estimate the fault location of double circuit transmission line. Those methods are Discrete Wavelet Transform algorithm and Fast Fourier Transform algorithm. Simulations has been carried out in MATLAB/Simulink and a variety of fault has been imposed in order to analyse the capability and accuracy of the fault location detection algorithm. Results obtained portrayed that both algorithms provide good performance in estimating the fault location. However, the maximum percentage error produced by the Discrete Wavelet Transform is only 0.25%, 0.6% lower than maximum error produces by Fast Fourier Transform algorithm. As a conclusion, Discrete Wavelet Transform possesses better capability to estimate fault location as compared to Fast Fourier Transform algorithm.</span>

Fast Current-Only Based Fault Detection Method in Transmission Line

When a fault occurs in transmission lines, first, it is detected, then classified, and finally, located by a distance protection. Having a fast fault detection approach helps saving the required time for the whole protection procedure. In this paper, a novel method for fault detection of transmission lines based on the summation of squared three-phase currents (SSC) and a moving average technique is proposed. The SSC is constant during a normal condition of the network, while it has considerable variation under a fault condition. Using a moving average concept, a criterion is defined, by which fault occurrence can be detected. The proposed fault detection method is evaluated in four different systems: a typical 5-bus system, a typical double-circuit transmission line, WSCC 9-bus system, and a laboratory small-scaled system. The results confirm a high degree of accuracy and speed of the proposed approach. Moreover, the performance of the method is compared with some other similar methods from different aspects.

Induced Voltage and Current Simulations, Safety Criterion, and Mitigation for EHV Transmission Lines in Close Proximity

One of the benefits of double-circuit transmission lines is that line maintenance work can be performed on a de-energized circuit while the other circuit remains energized. However, induced voltages and currents can be generated on the de-energized line due to electrostatic and/or electromagnetic coupling effects and the close proximity to energized conductors. In order to mitigate the safety concern related to high induced voltages or currents, line discharging grounding switches (LDGS) may be installed. Since this can be an expensive solution, the magnitude of induced voltage and current is the key for defining safety criteria to judge whether or not a costly mitigation plan is needed. This paper presents the theory of induced voltage and current and a sensitivity analysis of influential parameters that impact each. In addition, a safety criterion using arc reach calculation is proposed to determine when LDGS are required. A case study is included.

A protection technique for series capacitor compensated 400 kV double circuit transmission line based on wavelet transform including inter-circuit and cross-country faults

In this paper, wavelet transform based technique is introduced to detect and classify the faults in a series capacitor compensated double circuit transmission line. The three phase currents of both circuits measured at only one end of the series compensated double circuit transmission line are used to calculate the approximate and high frequency detail coefficients including wavelet energy content of each phase current signal. To evaluate the performance of proposed fault detection technique, simulation studies have been carried out on a series capacitor compensated double circuit transmission line test system. The major advantage of this proposed scheme is that it offers protection to entire transmission line length using one end fault current data only. The test results prove that all types of faults are correctly detected and the faulty phase is accurately identified using proposed technique. This technique is robust to the variation in fault type, fault inception time, fault resistance, ground resistance and fault location.Keywords: Fault detection, fault classification, series capacitor compensated double circuit transmission line, wavelet transform