Fault Location Error Research Articles

High impedance grounding fault location method for power cables based on reflection coefficient spectrum

When a high impedance grounding fault occurs in the power cables, the current at the fault point is extremely low and the fault characteristics are too weak to be detected by the reflectometry. Interfered by the multiple reflections, the fault is hard to be located in the field. In order to solve the problem of conventional frequency domain reflectometry, a high impedance grounding fault location method for 10 kV distribution cables is proposed in this paper, which is based on the reflection coefficient spectrum. Firstly, the equivalent model of cable distributed parameters is established, and the reflection coefficient spectrum at the cable head is derived. Then, according to the theorem of integral transformation and generalized orthogonality, the diagnostic function is built in the spatial domain. Besides, the Kaiser window is introduced to improve the location sensitivity. Finally, the feasibility of the method is verified by simulated and experimental results. It is shown that this method can effectively eliminate the impact of multiple reflections, and precisely locate the single- and multi-point grounding faults. The fault location error is within 0.2%.

Teager energy assisted variational mode decomposition‐based fault location technique for STATCOM compensated system

AbstractModern power systems are structurally complex and thus experience transient events. For secure and reliable operation, quick system restoration is required whenever transient phenomenon like line faults occurs. Fault location techniques (FLTs) aid in faster restoration process. However, the accuracy of FLTs gets affected in presence of static synchronous compensator (STATCOM) since STATCOM compensates the dip in measured voltage during fault thereby affecting the fault current signals. Therefore, in this paper, a Teager energy assisted variational mode decomposition (VMD) based traveling wave FLT is developed for transmission lines with STATCOM. The proposed FLT considers two‐terminal instantaneous voltage signals for locating faults. In this FLT, the signals are first decoupled into modal signals and then aerial mode of the signals is chosen for decomposition using VMD. The signals are decomposed via VMD to level three producing mode three signals. Teager energy of the resultant signals is obtained and from the first peak of the energy signals, arrival time of waves (ATWs) is estimated. These estimated ATWs are used to calculate fault location and percentage error. To validate the performance of proposed FLT, several test cases with different fault scenarios are considered and the results are compared with existing techniques. The results prove efficacy of proposed FLT for studied system.

A novel fault monitoring method based on impedance estimation of power line communication equipment

Due to the close relationship between power grid fault and impedance, there is a significant defect in the use of power line communication (PLC) equipment to monitor and locate power grid faults, which is the lack of real-time impedance information. Therefore, this study proposes a new fault monitoring method based on impedance estimation of power line communication equipment. The channel frequency response (CFR) obtained from the PLC receiver is used to estimate the high-frequency input impedance to monitor and locate the ground fault of the power grid in real time. Firstly, based on the multi-conductor transmission line theory, bottom-up channel modeling method and impedance estimation technology, the basic principles of fault monitoring and location methods are clarified. Then, modeling and analysis of cables in different situations are carried out, and the characteristics of the factors affecting the impedance in CFR are extracted by variational modal decomposition (VMD), and the estimation results of impedance are obtained by inversion analysis. Based on this, the impedance change and machine learning algorithm are used to track and identify the abnormal state of the power line to achieve high-sensitivity positioning of the cable fault. The simulation results show that the method has a good identification effect on high and low impedance cable fault, and has a better effect on low resistance fault monitoring. The fault location error is less than 2.13%, and has a good positioning accuracy.

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.

Learning picturized and time-series data for fault location with renewable energy sources

Transmission lines are heavy assets of power systems. Therefore, the rapid and accurate identification of fault locations is important for power grids’ safe and stable operation. Traditional methods based on impedances or traveling waves are facing increasing challenges like uncertain power generation and unknown power electronic device characteristics when modern power systems are transitioning to deeply renewable energy source (RES) penetrated grids. In order to solve the above problems, this paper proposes a high-dimensional time–frequency feature extraction method that does not require expert knowledge of physical features. This paper proposes a fault location framework for learning picturized and time-series data (FltLoc-FPTD) with renewables. The developed loss function is suitable for the classification of faulty lines, considering the challenges of distinguishing faults in adjacent lines. Furthermore, we design an enhanced convolutional neural networks (CNN) subsampling layer with blur kernels to replace the traditional subsampling layer to eliminate the influence of high-frequency noise and improve the robustness against noise. The effectiveness of the method is verified by simulation under two benchmark systems. The average fault location errors with and without environment noises are 0.0189 and 0.0124.

VSC-HVDC Fault Location Method Based on Effective Feature and Depth Belief Network

Aiming at the problems that most fault location methods are applied to the high voltage direct current (HVDC) transmission system, such as low location accuracy and vulnerability to noise, a voltage source converter (VSC)-HVDC fault location method based on effective feature and deep belief network is proposed. Firstly, the Karenbauer phase mode transform is used to decouple the original fault current data to eliminate the coupling effect between positive and negative lines. Then, Hilbert Huang (HH) transform is used to obtain six effective features of information from frequency domain and time domain analysis to fully characterize the system fault current signal. Finally, the extracted effective features are input into the depth belief network for learning, so as to estimate the fault location in the transmission line. VSC-HVDC system is built based on the MATLAB platform for experimental analysis. The results show that the fault location obtained by the proposed method has the smallest overall fault location error, and the maximum and minimum errors are divided into about 0.52 km and -0.95 km. Compared with other methods, it has certain advantages in fault location.

Fault Location Method for the Double-circuit Transmission Line Based on Electromagnetic Time Reversal

The current fault location ways for the double-circuit transmission lines on the same tower do not consider the coupling relationship of transmission lines. The fault location accuracy is low in practical application. Therefore, a fault location method for the double-circuit transmission lines on the same tower basing on electromagnetic time reversal is proposed in this paper. The six-sequence component method is used to transform the transmission line’s impedance matrix to eliminate the coupling between the lines of the double-circuit transmission line on the same pole. The positive and negative phase characteristics of the transmission line are analyzed by using the fault section identification function to decide the transmission lines’ fault section. The mirror line is constructed by applying the electromagnetic time reversal to measure the distance of the fault point. The experimental results indicate that the maximum error of fault location is only 0. 01 km for a double-circuit transmission line on the same tower, which has high measurement accuracy and good practicability.

Sensitivity Improvement in Cable Faults Location by Using Broadband Impedance Spectroscopy With Dolph-Chebyshev Window

Cable fault location is generally much more difficult if cable defect has not reached the level of serious breakdown. Traditional methods such as time domain reflectometry (TDR) and partial discharge detection cannot solve this problem well due to their low sensitivity. This paper proposes a new non-destructive detection method based on the impedance spectroscopy (IS), which can effectively locate soft faults in the cable. In this paper, a numerical model for cable with distributed parameters is established firstly. Based on this model, cable faults are extracted from the imaginary part of impedance spectrum with Discrete Fourier Transform (DFT). The Chebyshev window is introduced to suppress interference and enhance signal-to-noise ratio, which improves the sensitivity and accuracy of fault location significantly. Experiments and simulations show that this method can well locate multi-segment defects in cables with good accuracy. The window function successfully amplifies the normalized amplitude of faults and improves the positioning accuracy. Compared with other method, this method reduces distortion points effectively. The fault location error is within 0.53%, which has great potential for field application.

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.

Design and Implementation of Hybrid Transmission Line Protection Scheme Using Signal Processing Techniques

A hybrid scheme for transmission line protection (HSTLP) using the Stockwell transform (ST), Wigner distribution function (WDF), and alienation coefficient (ACF) is designed. Current signals are analyzed using the ST, WDF, and ACF to compute the Stockwell fault index (SFI), Wigner fault index (WFI), and alienation coefficient fault index (ACFI), respectively. These fault indexes are used to derive a hybrid signal processing fault index (HSPFI), which is implemented for the detection of transmission line fault events. The peak magnitude of HSPFI is compared with a preset threshold magnitude (TH) to identify the fault. The statistical formulation is proposed for fault location on the power transmission line. Fault classification is achieved using the number of faulty phases. A hybrid ground fault index (HGFI) is used to recognize the involvement of the ground during the fault event. This HGFI is determined by processing zero sequence current using ST and WDF. The performance of algorithm is tested by various case studies for fault impedance variation, variable sampling frequency, fault incidence angle variation, reverse power flow on transmission line, highly loaded line, different fault locations online, and noisy conditions. The algorithm is also validated to detect a fault on a practical transmission line of large area utility grid of Rajasthan Rajya Vidyut Prasaran Nigam Limited (RVPN) in India. The algorithm performs better than the Hilbert–Huang transform (HHT)-based protection scheme and wavelet transform (WT)-based protection scheme available in the literature in terms of mean error of fault location, fault location accuracy, and noise level. The proposed protection scheme efficiently detected, classified, and located the faulty events such as single-phase-to-ground fault (SPGF), two-phase fault (TPF), two-phase-to-ground fault (TPGF), three-line fault (TLF), and three-line-to-ground fault (TLGF). Transmission line fault location accuracy of 99.031% is achieved. The algorithm performs well even with a high noise level of 10 dB SNR.

Enhancing the resiliency of transmission lines using extreme gradient boosting against faults

The study presented in the paper aims to reduce the relaying time associated with detection and classification of fault along with accurate fault location estimation with the help of Teager Kaiser energy operator (TKEO) and extreme gradient boost (XGBoost) algorithm. The complete analysis has been conducted on IEEE 14 Bus transmission network. Four XGBoost modules corresponding to each phase have been developed for fault detection, classification, and similarly four regression modules are developed for fault location estimation depending on the type of fault. The proposed methodology is able to precisely determine the fault, locate it and also recognize the faulty phase(s). Special attention has been paid in determining the high impedance fault (HIF) apart from usual low impedance faults (LIF) while varying the fault parameters such as evolving nature of faults, fault inception angle, power flow angle and change in transmission line parameters etc. Voltage and current measurements recorded at the relay location are utilized. Moreover, the proposed XGBoost algorithm-based approach is able to detect and classify faults in around 1–2 ms time. The absolute error in fault location is around 0–2 km in most of the scenarios. A comparative study clearly states the merits of the proposed scheme.

Rearrangement Method of Reducing Fault Location Error in Tied Uncompleted Parallel Lines

In Tied Uncompleted Parallel (TUP) line, locating faults via single-ended fault location algorithm leads to a considerable final error yielding unacceptable outage time. On the other hand, utilizing modern techniques such as Two-ended Protection method, in these temporarily transmission lines are not economically justified. This paper proposes a rearrangement method of tied uncompleted transmission lines to improve the protection coordination and fault location via single ended fault location. This novel method aims to reduce the error of fault location in the line without imposing an unnecessary financial burden or installing new devices. The proposed technique can locate a fault online, resulting less outage time and more reliability of the network. The simulation results, as well as those of field test, indicate the effectiveness of the proposed method in locating fault according to different constraints such as the protection coordination. This method has already been implemented in the Fars-Iran power system since 2018, and it has yielded outstanding results in practice. The technique is easy to execute and considerably reduces the fault location error and the outage time. Having derived the factors of fault location error, the rearrangement technique suggests a new arrangement based on the fault location error factor reduction. In this paper, it is approved that the proposed algorithm can effectively locate faults in uncompleted transmission lines via simulation results as well as practical experience.

Economical Setting-Free Double-Ended Fault Locator for Transmission Lines: Experiences From Recent Pilot Installations

Locating fault precisely on power transmission line is highly beneficial to utilities and accurate fault location can expedite the repair of the faulted components, speed-up restoration, and reduce outage time. In this paper, a setting-free double ended fault location method for power transmission line is proposed using both end voltage and current measurements. This algorithm estimates the required setting parameters using pre-fault data and fault location is calculated using estimated parameters and during fault data. The proposed method is verified using the EMTDC simulations for lines connected with conventional and inverter-based renewable resources. The method is not affected by the error in line parameters and renewable integration. The method is implemented in Intelligent Electronic Device (IED) using 1kHz sampling rate and successfully installed on a 400 kV, 233.07 km line from Power Grid Corporation of India (POWERGRID), India and on a 220 kV, 265.6 km line from Svenska Kraftnat (SVK), Sweden. This paper presents laboratory test results as well as field experimental results in which line patrolling crews found the actual location. Pilot installation results match the performance demonstrated with laboratory experimental results. The method gives average fault location error of ~ 0.1 %. The method can locate the fault within two-tower span distance (~300m) which is comparable with traveling wave-based method that requires 1000 times higher sampling rate, high-cost hardware, more complex commissioning, and settings. These geographically diverse pilot installation results stand as testimony to the fault location accuracy of the proposed setting-free fault location solution.

New ground fault location method for three-terminal transmission line using unsynchronized current measurements

This paper presents a new ground fault location method for a three-terminal transmission line using unsynchronized current measurements. The faulty line section is identified utilizing the polarity of the second traveling wave that arrived at each terminal. Then, the fault is discriminated as either before or after the middle of the faulty line-section by observing the change in polarity among the first two consecutive traveling waves. Finally, the fault location is estimated at a particular terminal on which the faulty line-section is connected. The three-terminal transmission line model is simulated in PSCAD/EMTDC software. Various fault conditions are considered with wide variation in fault and system parameters to authenticate the proposed method. The obtained results depict the effectiveness of the proposed method for locating all types of internal ground faults. Further, the comparative analysis with several existing methods shows the supremacy of the presented method in terms of the fault location error for high resistance faults at different fault locations. Besides, its accuracy is minimally affected by the saturation of current transformers (CTs), errors in line parameters, and noise in the acquired signals.

선형 스플라인 보간법을 활용한 교류철도 고장점표정 보정기법에 대한 고찰

In this paper, we compare and analyze the characteristics of the boosting current ratio, which occurs differently depending on the ground configuration of the traction line, to derive the main causes of the fault location error. To this end, the Power system analysis program (PSCAD/EMTDC) is utilized to derive the characteristics of the boosting current ratio due to the other-line absorption phenomenon through modeling and simulation. Furthermore, to derive problems from existing calibration methods, we analyze facial expression errors by classifying single linear interpolation calibrations into multiple cases. We present a correction technique using linear spline interpolation to improve the accuracy of the fault point representation even under the nonlinear boost current ratio characteristic conditions due to integrated ground and other line absorption phenomena.

Data-Driven Probabilistic Fault Location of Electric Power Distribution Systems Incorporating Data Uncertainties

Current distribution system outage management is to separately use digital relays at the substation for estimation of fault location and use meter information to infer the activated protection device. The lack of holistic utilization of available data in the distribution operating center results in lost opportunities for accurate fault diagnosis. To solve this issue, this study proposes a data-driven probabilistic fault location methodology based on comprehensive sensing measurement from digital relays at substations, Intelligent Electric Devices (IEDs) along primary feeders, SCADA sensors in the feeder circuit, and smart meters at customers' premises. Statistics of historical fault location accuracies by digital relays and IEDs are used to estimate fault location errors with probability in real time. Multiple-hypothesis analysis is implemented to handle the uncertainties from SCADA sensors and smart meters. The spatial correlation between the potential fault location and collected sensor data is modeled as a mixed integer linear programming (MILP) problem. By solving the proposed optimization for generated hypotheses, a list of potential fault locations with possibilities is provided to system operators in decision-making for facilitated fault isolation and service restoration. Simulation results with a utility feeder validate the efficacy of the proposed approach for fault diagnosis.

Research on Transmission Line Fault Location Based on the Fusion of Machine Learning and Artificial Intelligence

After a transmission line fails, quickly and accurately find the fault point and deal with it, which is of great significance to maintaining the normal operation of the power system. Aiming at the problems of low accuracy of traditional traveling wave fault location methods and many affected factors, this paper relies on distributed traveling wave monitoring points arranged on transmission lines to study methods to improve the accuracy of traveling wave fault location on transmission lines. First, when a line fails, a traveling wave signal that moves to both ends will be generated and transmitted along the transmission line. We use the Radon transform algorithm to process the traveling wave signal. Then, this paper uses ant colony algorithm to analyze and verify the location and extent of transmission line faults and then optimizes high-precision collection and processing. Finally, the simulation distance measurement is carried out on double-terminal transmission lines and multiterminal transmission lines (T-shaped lines) with branches. The results show that, for double-ended transmission lines, the algorithm increases the speed of matrix calculations and at the same time makes the fault location error of the transmission grid still maintain the improved effect.

Impact of Resistive Superconducting Fault Current Limiter and Distributed Generation on Fault Location in Distribution Networks

Resistive Superconducting Fault-Current limiters (r-SFCL) appear as a new attractive technology to address faults in power grids. Based on a new generation of superconductors, referred to as High-Temperature Superconductors (HTS), they could offer economical benefits compared to more conventional technologies. To understand their impact on the electrical networks, two models of r-SFCL, differing by their complexity, were built to conduct short-circuit analysis. Different fault locations in distribution networks were studied in the standard IEEE 13-node and 34-node test feeders. Both models were validated against experimental data and then cross-checked in the IEEE 13-bus distribution system to determine their relative accuracy when used in practical power grids. Subsequently, using the simplest electrical model of r-SFCL, the 34-bus test system incorporating Distributed Generation (DG) was used to analyze short circuits. It was found that the presence of r-SFCL increases the error of the fault location algorithm. However, it was also demonstrated that a single r-SFCL enables the incorporation of several additional DG in a distribution network by reducing the fault current level by at least 45% depending on its design characteristics and the number of added DG. Finally, an improved algorithm is presented. This algorithm takes into account the r-SFCL resistance in order to reduce the fault location error.

Single-phase ground fault location method for distribution network based on traveling wave time-frequency characteristics

The traditional traveling wave fault location methods only consider the information about time domain or frequency domain characteristics, so it is difficult to ensure the location accuracy. Through the research of relationship between traveling wave characteristic parameters and frequency, this paper proposes a single-phase grounding fault location method based on traveling wave time-frequency characteristics. Firstly, determine the time during which the traveling wave reaches the busbar by using the quadratic B-spline wavelet analysis modulus maximum detection algorithm with denoising factor.. Then, according to the improved matrix pencil algorithm, extracte the frequency of traveling wave arriving at the bus measuring point, and the corresponding velocity of incident wave is obtained. Finally, the fault distance can be calculated using the location equation of modulus wave velocity difference. The simulation results show that this method proposed in this paper has higher accuracy than the traditional method, and in the terms of different grounding resistance, fault initial angle and fault distance, the error of fault location is smaller.

A Novel Fault Location Approach for Scientific Cabled Seafloor Observatories

The maintenance of scientific cabled seafloor observatories (CSOs) is not only extremely difficult but also of high cost for their subsea location. Therefore, the cable fault detection and location are essential and must be carried out accurately. For this purpose, a novel on-line fault location approach based on robust state estimation is proposed, considering state data gross errors in sensor measurements and the influence of temperature on system parameter variation. The circuit theory is used to build state estimation equations and identify the power system topology of faulty CSOs. This method can increase the accuracy of fault location, and reduce the lose form shutting down a faulty CSO in traditional fault location methods. It is verified by computer simulation and the laboratory prototype of a planned CSO in the East China Sea, and the fault location error is proved to be less than 1 km.