Actual Fault Location Research Articles

Traveling wave network location method based on adaptive waveform similarity

High-voltage transmission technology can effectively address the issue of uneven spatial and temporal energy distribution, leading to its rapid development in recent years. To address the challenge of accurately identifying the source of the second traveling wave head in complex transmission network scenarios with existing single-ended fault location methods, a traveling wave network fault location method based on adaptive waveform similarity is proposed. The paper analyzes the propagation process of traveling waves in transmission lines and quantitatively derives the time-domain expression of the traveling wave waveform. The BFS algorithm is enhanced by incorporating the propagation characteristics of traveling waves, allowing for the determination of all paths from any location in the topological network to the measurement points. Based on the path information and the derived expression, the traveling wave waveform at the measurement points for the fault location is calculated. An optimization algorithm is used to iteratively solve for unknown parameters such as fault location, traveling wave speed, and fault point information, with the objective of maximizing the similarity between the adaptive waveform and the real waveform by adaptively adjusting the waveform shape. When the similarity between the adaptive waveform and the real waveform is maximized, the adaptive fault location is identified as the actual fault location. Verified through the PSCAD simulation platform, this method can achieve accurate location under different fault conditions.

Electric Fault Location Methods Implemented on an Electric Distribution Network.

This paper compares two electric fault location techniques, [1]&[2]. Using prefault and fault data (voltages and currents) and a model of the network, the algorithms can give an approximation of the actual fault location. They were chosen because the final aim is to implement them on a real distribution network, where we have registered faults with the prefault and fault information, and where the parameters of the network are known. Both techniques were implemented on simple lines and tested through simulations. The results obtained, showed that Ratan Das algorithm was giving better approximations to the actual fault. On a second step the algorithms were implemented on a real distribution network. The results also showed that Ratan Das algorithm give better results and is less sensible to fault impedance, a parameter that in the majority of cases is unknown. An application with a graphical user interface has been created to execute the methods, but also to execute the necessary previous steps: obtain the phasors of the fault, either through a simulation or loading actual registered faults, graphical representation of waveforms and phasors... In conclusion, the Saha method is easy to implement but an evaluation of the fault resistance is needed, and this let the method to be more sensible at uncertainties.

An extended impedance‐based fault location algorithm in power distribution system with distributed generation using synchrophasors

AbstractAccurately locating power distribution faults reduces the total outage duration and provides better system reliability. Fault location using the traditional impedance‐based method may be very challenging in an active distribution system. However, taking into consideration the ease of implementation and cost effectiveness, a novel impedance‐based method is proposed to locate the fault by using the highly accurate time‐synchronized voltage and current phasors obtained from distribution phasor measurement units. The synchrophasor measurements obtained from the substation and various feeder segments are used in a two‐step algorithm based on the apparent impedance calculation to locate the exact source of the event. The algorithm uses phasor estimates to first identify the faulted feeder sub‐region and later uses measurements from a remote end device to eliminate pseudo‐faulted points to obtain the actual fault location. The effectiveness of the proposed method is realized using IEEE 34 bus system. Based on different fault types simulated at various parts of the system, the algorithm accurately estimates fault location in the range of ±1% of the line length. The proposed method is effective in locating faults for any type of network and topologies, with as many or as few (minimum 2) phasor measurement units in the system.

Electromagnetic Time Reversal Fault Location Method Based on Characteristic Frequency of Traveling Waves

In its application to locate ground faults, the electromagnetic time reversal (EMTR) method uses voltage from only a single point. However, when a high-impedance fault (HIF) occurs, the reflected signal from the fault point is weak, leading to an error between the simulated and actual fault location results. This paper proposes a new EMTR method based on the characteristic frequency of the traveling wave reflecting from the fault point. First, the transient signal spectrum under different fault resistances was analyzed, and the reasons for the inapplicability of the existing EMTR method under HIF conditions were discussed. Subsequently, a single-end signal expression with fault resistance was deduced, and the applicability of the EMTR method, which involves calculating only the energy of the fault current at the characteristic frequency, was verified. A reduced-scale experiment and a simulation in PSCAD were performed, and the EMTR method and proposed method were compared. The results showed that the proposed method can be applied to different complex lines, and it outperforms the conventional EMTR method in the event of HIFs.

Step Frequency TR-MUSIC for Soft Fault Detection and Location in Coaxial Cable

Soft faults in cables may trigger short circuits and open circuits in time, in that, they ought to be detected and thus eliminated at an earliest possible stage, as to ensure safe and stable operation of the cables. A method called the time-reversal multiple signal classification (TR-MUSIC) had been proposed in the literature, which has been demonstrated to be an effective technique for locating soft faults in cables, owing to its high resolution and excellent noise robustness. However, traditional TR-MUSIC relies on a vector network analyzer for measuring the scattering matrix of cables, which adds cost and complexity to its implementation. In this regard, a new way of acquiring the desired scattering parameters is herein proposed. An arbitrary function generator is used to inject incident signals into the cable under test, and an oscilloscope is used to collect the reflected signals. After post-processing, the phase of scattering parameters can be obtained. There’s another key issue in the image of the detection results, ghost traces caused by the periodicity of Green’s function severely impact the vision saliency of the actual fault location, which limits the performance of the fault location. A step frequency variant of TR-MUSIC has been proposed, therefore, to mitigate ghost traces. Experimental results show that the fault location error of the proposed approach is smaller than 0.33% for a 51-m long coaxial cable. Moreover, in the case of introducing noise, the proposed approach can operate in situations with signal-to-noise ratios as low as –6 dB.

Transmission Line Fault Location in MMC-HVDC Grids Based on Dynamic State Estimation and Gradient Descent

This paper proposes a new fault location method for transmission lines in MMC-HVDC grids based on dynamic state estimation (DSE) and gradient descent. The method only requires a short data window of 5 ms after the occurrence of the fault and therefore is applicable for MMC-HVDC grids with high-speed tripping techniques. The method first builds a high-fidelity linear dynamic model of the DC transmission line, which accurately describes physical laws of the transmission line during the fault. Afterwards, the consistency between the measurements and the linear dynamic model is evaluated through the DSE algorithm. Finally, the actual fault location which corresponds to the best consistency is determined via the gradient descent algorithm. Compared to the existing DSE based fault location methods which solve highly nonlinear DSE problems, the proposed method only needs to solve a series of linear DSE problems, which overcomes the issues such as large numerical error and high computational burden especially for transmission lines in MMC-HVDC grids. Numerical experiments validates the effectiveness of the proposed method, with different fault types, resistances and locations. In addition, the method only requires a relatively low sampling rate of 20k samples per second.

Practical Methodology for Two-Terminal Traveling Wave-Based Fault Location Eliminating the Need for Line Parameters and Time Synchronization

This paper presents a practical methodology for traveling wave (TW)-based fault location on homogeneous transmission lines. It provides improvements in the fault location accuracy in real-world scenarios by eliminating the influence of uncertainties in line parameters and data time synchronization errors, which are potentialities not readily available in actual micro-processed fault location devices. A commercially available software for TW analysis is proposed to be used as a support tool to compute auxiliary variables, from which the accurate fault distance is estimated. Real and simulated TW fault records are assessed, from which the proposed fault location procedure is evaluated, highlighting its step by step. The obtained results show that the proposed methodology is straightforward and reliable, being quite useful for field applications.

A Two-Stage Fault Location Identification Method in Multiarea Power Grids Using Heterogeneous Types of Data

This paper proposes a two-stage fault location method for multiarea power systems. It utilizes available heterogeneous types of data consisting of status data (i.e., discrete data) and analog data (i.e., continues data). A distributed casual model-based diagnosis method using P-invariant Petri nets is proposed that utilizes status data to find faulted sections. Each subsystem/area of multiarea power systems has its own diagnostic model and determines the diagnosis solution based on its local net, the local manifestations, and limited information exchange with the neighboring subsystems/areas. Once a short list of possible fault sections is determined, the second stage further improves the estimated fault location using analog data. The actual fault location is estimated by comparing the measured analog data with their associated calculated values in computer programs using short-circuit analysis algorithms. Simulation results demonstrate that the proposed distributed fault location method can diagnose faults in multiarea power systems accurately.

Wavelet‐based EMTR method for fault location of VSC‐HVDC transmission lines

A wavelet-based electromagnetic time reversal method for locating faults in voltage source converter-high-voltage direct current (VSC-HVDC) transmission lines is proposed in this study. This principle, firstly, is to use wavelet decomposition to filter the 1-mode fault currents, which are recorded at ends of the transmission line. Secondly, the filtered currents are mirrored on time axes, which called time reversal. Thirdly, the time-reversed currents are set as current sources at ends of the lossless mirror lines. Through assuming a fault at each point of line, the assumed fault currents are calculated, and the RMS of fault current at actual fault location is maximal according to a strict scientific proof. Theoretically, the Wavelet-based Electromagnetic Time Reversal (WEMTR) method is robust against fault types and resistance. A multilevel converter-HVDC system is established in Power Systems Computer-Aided Design (PSCAD)/Electromagnetic Transients including DC (EMTDC) to verify the feasibility of the proposed method, and the transmission line is simulated by frequency independent phase model. The results show that, the fault location can be calculated exactly without high sampling rates.

A New Theory for Locating Line Fault in Power System: Theoretical Part

This paper proposes a theory for locating line fault based on the basic principle of time reversal. The proof has five steps. First, the theoretical voltage and current at the ends of the line are calculated based on the transmission equation of the line in the additional network after line fault occurred. Second, the loss and lossless mirror line are established according to the parameters of the actual line. Third, the values of the implemented sources at the ends of the mirror line are calculated based on the conjugate complex of the theoretical values of voltage and current in the first step. Fourth, the RMS value of the fault current is calculated by assuming that fault occurs at every point of the mirror line. Finally, we should identify that there is only one peak value among all the RMS values and it exists at the actual fault location. In this paper, the fault location theory is proved with and without reflected waves by using the transmission equation of a single line. It is further proved in the mixed line that consists of two lines of different parameters considering the reflections.

Low Voltage Zones to Support Fault Location in Distribution Systems With Smart Meters

This paper proposes to combine the voltage monitoring capability of smart meters with impedance-based fault location methods to provide an efficient fault location approach improving service restoration. The first step of the proposed methodology is to apply an impedance-based method to obtain a rough estimation of fault location. Since the result is an estimated distance to the fault, multiple branches can be indicated due to the typical distribution systems topologies. Therefore, the challenge is: how to recognize the actual fault location? To solve this problem, voltage measurements from smart meters are used to build the low voltage zones (LVZs). The main contributions of the proposed fault location technique are to decrease the multiple estimations associated with impedance-based methods, to propose a systematic approach to build the LVZs, and to explore the presence of smart meters for fault location. The proposed method was tested through intensive and extensive simulations in a real distribution system, proving its efficiency.

Real-Time Adaption of Dead Time for Single-Phase Autoreclosing

An approach for a real-time adaption of the dead time for autoreclosing on high-voltage lines was proposed. The objective was the optimal adaption of the dead time of a currently running single-phase autoreclosing cycle by calculating the secondary arc current based on measurements. The algorithms for optimization were performed for real-time applications. For this purpose, the fault location plus the load currents of the parallel nonfaulty conductors were measured. The measurement and the calculation of the dead time took place during the fault and the dead-time period. In this way, an optimized dead-time setting with regard to the actual fault location and loading conditions were achieved. This approach results in an online determination of the minimum necessary dead time of a successful reclosing under consideration of the fault location and prevailing loading conditions. Analytical calculations and numerical examples as well as high-voltage field tests verified the results.

One-end impedance based fault location in double-circuit transmission lines with different configurations

• One-end impedance based fault location method for double-circuit transmission lines with eight different configurations. • Developed in phase coordinates and does not require six-order sequence component transformation. • Fault data for verification are obtained using MATLAB – Simulink. • Results shown that the method is accurate and robust. A one-end impedance based fault location method suitable for double-circuit transmission lines with different end configurations is presented in this paper. The effect of mutual coupling of the circuits is taken care of in developing the algorithm. The method is developed in phase coordinates and hence it does not require the complicated six-order sequence component transformation. It is applicable to both symmetrical and unsymmetrical lines. Depending on the terminations at both ends of the line, eight different cases are discussed. The fault data required to evaluate the effectiveness of the method are obtained by simulating faults in different types of double circuit lines using MATLAB/Simulink. The accuracy of the proposed technique is evaluated by comparing the computed fault location with the actual fault location in the simulated models. It is shown that the method is accurate and robust for small errors in estimated equivalent source impedances.

Fault Simulation of Relay Valve Based on AMEsim

This paper analyzes the principle and structure of the relay valve, and AMEsim software is used to build up a relay valve model which can be used to simulating fault. And the model has been verified by comparing to the routine test data. Considering failure mechanism of various components of the relay valve, a modified relay valve model which can simulate some kinds of typical fault is built up. The braking system performance is researched under different kinds of fault. By analyzing and classifying the characteristics of brake cylinder pressure curve, piston displacement curve under kinds of fault condition, the fault reasons and actual fault location can be detected, which provides help for the relay valve maintenance and fault detection.

Optimal placement of faulted circuit indicators in power distribution systems

AbstractPower distribution utilities often use impedance-based methods for locating faults along their feeders. For feeders with laterals, these techniques may identify different possible locations for the same fault. This leads to higher costs and longer restoration time. In order to improve impedance-based methods, faulted-circuit indicators (FCI) can be allocated along the feeder to reduce, or even eliminate, the uncertainty about the fault location. This paper proposes a technique for optimally allocating a given number of FCIs along distribution feeders using the Chu–Beasley genetic algorithm to solve the optimization problem. The proposed objective functions measure the number of locations that are suspected to be the actual fault location or the distance among them. Additionally, it is possible to consider the presence of priority areas. We present results for the IEEE 34-bus system and for a 475-bus actual system. The results show the effectiveness of the proposed technique in improving impedance-based fault location methods.

A Novel Fault-Locator System; Algorithm, Principle and Practical Implementation

This paper presents a novel fault-locator system for radial distribution feeders based on the feeder architecture and voltage and current measurements at a subtransmission substation (63/20 kV). The proposed algorithm determines the fault location precisely by considering the variable characteristic of the load, unbalanced condition, and unsymmetrical nature of distribution feeders. Load variations affect the accuracy of fault-locator systems significantly. Real-time load estimation is implemented to reduce the differences between the calculated fault location and the actual fault location. In addition, self-supervisory characteristics are added to the system to increase the accuracy of the collected data. Actual test results demonstrate the effectiveness of the system in practical applications.

Automated fault location and diagnosis on electric power distribution feeders

This paper presents new techniques for locating and diagnosing faults on electric power distribution feeders. The proposed fault location and diagnosis scheme is capable of accurately identifying the location of a fault upon its occurrence, based on the integration of information available from disturbance recording devices with knowledge contained in a distribution feeder database. The developed fault location and diagnosis system can also be applied to the investigation of temporary faults that may not result in a blown fuse. The proposed fault location algorithm is based on the steady-state analysis of the faulted distribution network. To deal with the uncertainties inherent in the system modeling and the phasor estimation, the fault location algorithm has been adapted to estimate fault regions based on probabilistic modeling and analysis. Since the distribution feeder is a radial network, multiple possibilities of fault locations could be computed with measurements available only at the substation. To identify the actual fault location, a fault diagnosis algorithm has been developed to prune down and rank the possible fault locations by integrating the available pieces of evidence. Testing of the developed fault location and diagnosis system using field data has demonstrated its potential for practical use.

Efficient fault location for globally controlled and comparison-based multistage interconnection networks

Procedures for fault location in globally controlled and comparison-based multistage interconnection networks (MINs) are presented. The number of tests is constant or depends logarithmically on the network size. The tests are independent of the actual fault location and type which yields reduced time consumption and simple implementation. Furthermore, these procedures are well suited to be implemented for a built-in self test.

Transmission line fault location using digital fault recorders

A technique for the location of transmission line faults using voltage and current measurements from one end of the faulted line is presented. The method differs from past approaches in that a time domain rather than a frequency domain representation of voltage and current is used. A phase network model is used, permitting explicit treatment of self and mutual impedance effects for either a single three-phase circuit or two parallel three-phase circuits. The algorithm will be used as one of the analysis functions for a digital fault recorder. Test results are presented to illustrate the performance of the algorithm under various system conditions and configurations. Results compare favorably with those obtained using previously reported fault location methods. Estimated fault locations are within 3 to 4% of the actual fault location. Most cases show errors within 2% of the actual fault location. >

Computer aided feature selection for enhanced analogue system fault location

A digital computer based technique for the selection of optimum test frequencies for fault diagnosis of analogue systems is presented. Gain and phase deviations from the nominal system response for changes in component values are evaluated and the recognition matrix is established which in turn is normalized and made sparse. The heuristic optimization technique developed is applied to the sparse recognition matrix to select the best subset of features via a discriminatory index of measurement points by adding or discarding features until the optimum is found. The efficiency of the selected feature set is measured by the confidence level formally incorporated in the algorithm and which is found to correlate well with the actual diagnosability of faults for a simulation of varying fault levels and including varying production tolerances for the non-faulty components. Actual fault location is implemented using the nearest neighbour rule, which is complimentary to the feature selection technique. Only three measurements are found to be sufficient to achieve a high level of diagnosability. The simulation of 91,000 faulty 7 component passive circuits has been undertaken to verify the procedure, which may now be applied equally well to larger scale systems using input-output measurements only, or, alternatively on sub-systems of comparable size to the sample circuit which have been isolated by special electronic partitioning devices as recently proposed for the fault location in television receivers during the manufacturing process.