Improved Fault Location Research Articles

Undersea observation network fault location method considering the ocean circuit

Due to the harsh marine environment, submarine cables in the undersea observation networks are easily damaged which leads to the fault and power failure. An accurate fault location method is required for the fast power recovery and repairment for the undersea observation networks. Most of the fault location methods for undersea power system ignore the ocean circuit, which result in a decrease in fault location accuracy. This paper proposes a fault location model for undersea observation system based on steady-state post-fault power system operation data considering ocean circuits. The ocean as an equipotential body is considered as a node for calculation. According to Kirchhoff's current law, the current vector can be reconstructed and the influence of the current error of each branch on the fault location can be eliminated, which improves the accuracy of fault location method. A simplified model of NEPTUNE is simulated in PSCAD to prove that the proposed method is available to locate multi types of faults in the undersea observation network power system. The results show that the improved fault location method is more precise than the original method.

Improved fault location method for AT traction power network based on EMU load test

The autotransformer (AT) neutral current ratio method is widely used for fault location in the AT traction power network. With the development of high-speed electrified railways, a large number of data show that the relation between the AT neutral current ratio and the distance from the beginning of the fault AT section to the fault point (Q–L relation) is mostly nonlinear. Therefore, the linear Q–L relation in the traditional fault location method always leads to large errors. To solve this problem, a large number of load-related current data that can be used to describe the Q–L relation are obtained through the load test of the electric multiple unit (EMU). Thus, an improved fault location method based on the back propagation (BP) neural network is proposed in this paper. On this basis, a comparison between the improved method and the traditional method shows that the maximum absolute error and the average absolute error of the improved method are 0.651 km and 0.334 km lower than those of the traditional method, respectively, which demonstrates that the improved method can effectively eliminate the influence of nonlinear factors and greatly improve the accuracy of fault location for the AT traction power network. Finally, combined with a short-circuit test, the accuracy of the improved method is verified.

An Improved Noniterative Parameter-Free Fault Location Method on Untransposed Transmission Lines Using Multi-Section Models

This paper proposes an improved noniterative fault location method on untransposed transmission lines without utilizing line parameters. Two-end three phase voltage and current phasor measurements before and during the fault are typically required. First, the parameter-free fault location problem is formulated through multi-section transmission line models, and the necessary condition of noniterative solutions is carefully investigated to determine the maximum possible section number of the multi-section line model. Afterwards, with the determined section number, the analytical solution of the fault location is derived with full utilization of the inherent characteristics of the line parameter matrices. Instead of solving all the parameters, two key variables inside the parameter matrices are extracted and the fault location is obtained by analytically solving a polynomial equation. The method provides a closed-form analytical solution, and therefore avoids convergence issues of iterative algorithms. In addition, line asymmetry of untransposed transmission lines are fully considered to minimize fault location errors. Extensive numerical experiments show that the proposed method has improved fault location accuracy compared to the existing method, with different fault types, locations and impedances.

The improved fault location method based on natural frequency in MMC-HVDC grid by combining FFT and MUSIC algorithms

The fast and accurate fault location is extremely important for effective fault clearance in the power system. And in HVDC grid, the natural-frequency based fault location method is quite promising. Therefore, in this paper, the applicability of the traditional natural-frequency based method in MMC-HVDC grid is analyzed. Then the improved method suitable for MMC-HVDC grid is proposed. In the proposed method, the second natural frequency is discriminated and extracted to calculate the fault distance, because the first natural frequency is very low and used data window is very short in MMC-HVDC grid. In addition, the scheme combinedly utilizing FFT and MUSIC algorithms is designed, to avoid influence of traditional MUSIC false frequency phenomenon. A four-terminal meshed dc grid model is built based on PSCAD/EMTDC, and the simulation cases are carried out to verify the correctness of theoretical analysis and superiorities of proposed method. Compared with traditional method, the proposed one calculates fault distance based on a shorter data window, thus being more suitable for MMC-HVDC grid. And the influence of the MUSIC false frequency phenomenon is avoided, further guaranteeing the fault location accuracy.

The improved fault location method for flexible direct current grid based on clustering and iterating algorithm

The fault location method based on the natural frequency of the fault travelling wave has outstanding superiority in high-voltage dc system, because of high operation speed, acceptable sampling rate, and so on. However, in flexible dc grid, the natural-frequency characteristic is quite different from that in conventional high-voltage dc system, meaning the existing fault location method cannot be directly used. This paper analyses the distance-frequency characteristics in different stages of fault period (from fault occurrence to fault isolation) in flexible dc grid, to find a suitable stage for fault location. On the basis of this, the improved fault location method based on clustering and iterating algorithms is proposed. Compared with the traditional method which directly uses the multiple signal classification algorithm to estimate the natural frequency for fault location, the proposed method can effectively eliminate the large error caused by signal dimension fluctuation and false spectrum peak of multiple signal classification algorithm. Finally, simulation cases are carried out to prove the feasibility and superiority of the proposed method.

Improved Fault Location Algorithm for Radial Distribution Network Based on Power Failure Information

As the scale of the distribution network continues to increase, the importance of distribution network is getting higher and higher. Therefore, it is necessary to achieve fault location and restore it as soon as possible after the fault occurs. This paper proposes a new fault location algorithm for the radial distribution network, which is improved on the basis of traditional matrix algorithm. First, the power failure incidence matrix (PFIM) and power interruption information matrix (PIIM) is constructed based on the topological connection and fault information at each node. The fault location matrix (FLM) is then obtained through PFLM and PIIM to realize the fault location. Second, the accuracy of the proposed algorithm is verified by mathematical derivation. Finally, an 11-node radial distribution network is illustrated to testify the proposed algorithm. Results show that the improved fault location matrix algorithm proposed in this paper can effectively achieve fault location in radial distribution network.

Fault location method based on three-phase asymmetric phase current fault component and Euclidean distance

When a single-phase ground fault occurs in the distribution network, the three-phase current fault components of the fault path and the non-fault path in the system will be difference which can be used as a criterion for fault line selection. However the three-phase load current in the system is much larger than the fault component current, the three-phase phase fault component current is not obvious, which will cause the failure of the method. This paper proposes an improved fault location method based on the three-phase phase current: the fault component of the three-phase current of the system is obtained by subtracting the phase current before the fault occurs from the after. And then the zero-sequence current of this line is subtracted from the fault component to enhances the difference between the lines, and the fundamental amplitude of the result is obtained. The algorithm uses the three-phase fundamental amplitude as the coordinate axis to establish a coordinate system. The difference between the fault path and the non-fault path is enhanced by calculating the Euclidean distance of the three-phase current fundamental amplitude. And the location of the fault section can be judged locally by comparing the overall differences between the lines. In this paper, the specific fault section location process and criteria are proposed, and the feasibility of the method is verified by simulation experiments and actual field data.

Surge Compression for Improved Fault Location Accuracy in Full Transient-Based Methods

This paper proves that the accuracy of single-ended fault location techniques based on the correlation of fault transients in power lines can be significantly improved by inverse-filtering transients first. The reason for this improved accuracy is found in the reduction of the duration of the fault surge signal, thus increasing the sensitivity of fault-location metrics to the fault position. Reported results show that by using the proposed filtering strategy, faster sampling rates systematically and significantly improve the location accuracy, as opposed to the case when no filter is applied, for which virtually no improvement is observed. Because of its higher spatial selectivity, the proposed fault-location technique required the development of a new synchronization method, which ensures a precise transient synchronization without the need for high-speed sampling. It is concluded that by jointly using the proposed transient filtering and synchronization solutions, correlation-based fault location can be significantly improved even when using sampling rates as low as 100 kHz. Extensive numerical simulations for a three-phase transmission line confirm an improvement exceeding one order of magnitude in the fault location accuracy, for both low- and high-impedance faults.

Improved fault location algorithm for MV networks based on practical experience

Improved fault location algorithm for MV networks based on practical experience

Improved fault location algorithm for multi‐location faults, transforming faults and shunt faults in thyristor controlled series capacitor compensated transmission line

Fault location estimation in series compensated transmission lines is quite difficult because a non-linear current dependent circuit appears between the substation and fault point. In particular, the faults which occur at different locations at the same time in different phases known as multi-location faults has not been addressed by researchers. Other types of fault that may occur in transmission lines are transforming faults where one type of fault transforms to another type fault after some time. In this study, a fault location estimation scheme using artificial neural network (ANN) is presented for multi-location faults, transforming faults as well as for commonly occurring shunt faults in thyristor controlled series capacitor (TCSC) compensated transmission line. DB-4 wavelet is used for pre-processing of the three-phase current and voltage signals. The shunt capacitance of the line is considered based on distributed parameter line model. Feasibility of the ANN-based fault location algorithm is tested under a wide variation of parameters, such as fault type, location, fault resistance and fault inception angle. Fault location errors are within 0.001–1% range.

Improved fault location algorithm for radial distribution systems with discrete and continuous wavelet analysis

Abstract This paper presents a novel wavelet based approach for fault location using voltage transient waveforms in power distribution systems. The proposed method includes two main stages. Firstly, the approximate location of the fault or fault section is determined using a new algorithm with discrete wavelet transform. The difference between arriving times of transient components in different measurement units is used for this purpose. The accurate location of the fault is determined in the second stage. Depending on the determined fault section, the difference between arriving times of transient components in different measurement units or the frequency content of the voltage transients are used. The time difference and frequency content are calculated using discrete and continuous wavelet transform (DWT and CWT) respectively. The proposed technique is implemented on an unbalanced 34 bus distribution system with two distributed generation units which is simulated in ATP–EMTP. The comparison of the results of the proposed method with previous works verifies its better accuracy and more robustness to fault conditions including fault inception angle and fault resistance.

Improved Fault Location Through Analysis of System Parameters During Autoreclose Operations on Transmission Lines

This paper describes a novel single-ended impedance-based fault-location method for transmission lines, which is based upon the analysis of voltage and current during discrete system states that arise during the operation of single- and three-phase autoreclose schemes. A fault-location estimation algorithm, using the data measured during various system states and is capable of locating the fault types involving one fault resistance (i.e., single-line-to-ground fault or line-to-line fault), is developed and presented. The proposed fault-location technique is shown to have high accuracy; results are presented and compared with the well-established Takagi method and the performance of the algorithm is analyzed and discussed. The proposed technique can reduce or negate limitations associated with conventional single-ended methods and can also estimate other factors associated with the fault (e.g., fault resistance and remote source impedance). In addition, it is a potentially economic solution, since it is relatively straightforward to implement on a standard protection relay hardware platform. The proposed method is demonstrated using Electromagnetic Transients Program/Alternate Transients Program simulation models for a variety of different cases. This paper concludes with an overview of ongoing and future work that has the intention of moving the work forward toward implementation within commercially available relay hardware.

DEVELOPMENT AND DETERMINATION OF VOLTAGE-FAULT-LOCATION AND LINE-FAULT-LOCATION (LENGTH OF LINE) ON LONG TRANSMISSION-LINE (200 MILE = 320 KM) (IFLM).

Abstract Fault location and fault-voltage problems have been presented as a major challenge in electrical power system analysis, most of these methods uses voltage and currents measurements at either one ends or both ends of a transmission line. This work presents a faultlocation/fault-voltage problems. An improved fault location model (IFLM) are developed to search for fault location in a long transformation line say (200 mile), thereby determining a set of values for a set of unknown system state variables, based on certain criterion making use of the measurements mode from the system under consideration.

Improved Fault Location on Distribution Feeders Based on Matching During-Fault Voltage Sags

A fault location algorithm for distribution feeders based on matching during-fault voltage sags is presented. The basic principle of the algorithm is based on the fact that when a fault occurs on the feeder, voltage sags propagate presenting different characteristics for each feeder node. Knowing the voltage sag characteristics, it is possible to locate the faulty node or the faulty area of the feeder. This voltage-based approach ensures the efficiency and robustness of the algorithm, which provides suitable and accurate results. An overhead, three-phase, three-wire, 13.8 kV, 134-node, real-life feeder model is used to evaluate the algorithm. Test results show that the algorithm is quite suitable due to not only the faulted point being located, but also a faulted area being identified providing important information to direct the maintenance crew seeking to repair any fault inflicted damage.

Development of Waveform Reconstruction Method with Current Transformer Saturation

This paper presents a new technique of waveform reconstruction method with CT (Current Transformer) saturation in power system. The authors have developed the method of waveform reconstruction using secondary current waveform of CT during a non-saturation. It is the method to identify variables of a mathematical model of primary current waveform of CT. We applied this technique to real current waveform in the fault of 66kV transmission line and confirmed the effectiveness. And we report the result that applied the proposed method to fault location of transmission line. In verification of fault location, we confirmed that the proposed method has improved fault location precision.

Use of time delays between modal components in wavelet based fault location

This paper presents an improved fault location method based on the traveling wave theory of the transmission lines. Fault transients recorded at one end of a transmission line are processed to determine the distance from the fault location. Wavelet transform is utilized for this purpose. The proposed method also takes advantage of the different travel times of the modal components in differentiating between close-in and remote end faults. The approach has the advantages of being independent of the fault impedance, mutual coupling effects and series compensation capacitors. The method's performance for typical faults is illustrated using transient simulations obtained by an electromagnetic transients program.