Fault Location Error Research Articles

High‐speed algorithm for fault detection and location in DC microgrids based on a novel time–frequency analysis

AbstractProtecting DC microgrids (DCMGs) from faults is critical due to the rapid current changes that occur in milliseconds. However, ensuring fast and accurate protection in DCMGs is more challenging than in AC systems. This study proposes a novel protection algorithm using traveling waves (TWs) for fault detection and localization. The high‐order synchrosqueezing transform (FSSTH) is applied to precisely identify TWs at the relay location. FSSTH offers a sharp time–frequency representation, enhancing the accuracy and speed of fault detection. This method can accurately detect transient phenomena like TWs in DCMGs, even with noise and variable fault resistance. By using the spectral envelope with FSSTH, ridges in time–frequency representations are extracted, improving fault diagnosis. The approach differentiates external from internal faults and recognizes fault direction by assessing TW polarity. Testing on two different DCMGs showed this algorithm's high efficiency and accuracy, with fault location errors ranging from 1 to 50 meters in low‐voltage and 13 to 64 meters in medium‐voltage DCMGs, even under challenging conditions like high resistance (up to 500 Ω) and low signal‐to‐noise ratio (5 dB). These results demonstrate the method's superior accuracy and robustness compared to existing techniques.

A novel phaselet-based approach for fault detection and location in HVDC lines

Recently, the popularity of direct current (DC) transmission has surged due to a 30 % reduction in power electronics equipment costs over the last decade. High-Voltage Direct Current (HVDC) transmission lines experience fluctuations in both nominal and faulty states, posing challenges for fault location methods, particularly those based on traveling waves, resulting in imprecise outcomes with an average error margin of ±2 %. This paper investigates a novel fault detection and location approach utilizing wavelet and phaselet transforms. The proposed method focuses on traveling waves in HVDC transmission lines, where the phaselet transform effectively eliminates undesired fluctuations in line currents, improving fault detection accuracy by up to 15 %. By leveraging the traveling time in the faulty line, the exact fault location is calculated with an accuracy of 98.5 %, independent of transmission line parameters, making it applicable to any DC line. Additionally, the method's precision is minimally affected by fault resistance, with <0.5 % deviation even in nonlinear scenarios. Sensitivity analysis conducted on various parameters, including mother wavelet patterns, suggests the optimal solution for each fault type, enhancing detection speed by 20 %. The proposed method is validated using the Cigre HVDC benchmark, confirming its accuracy, speed, and robustness in fault detection and location in HVDC lines. The main contribution of this paper is an accurate, fast, and robust phaselet-based algorithm that reduces fault location errors to <1 % and is applicable to all types of bipolar and monopolar HVDC systems, delivering reliable results for both ground and line faults.

A physics-informed data-driven fault location method for transmission lines using single-ended measurements with field data validation

Data driven transmission line fault location methods have the potential to more accurately locate faults by extracting fault information from available data. However, most of the data driven fault location methods in the literature are not validated by field data for the following reasons. On one hand, the available field data during faults are very limited for one specific transmission line, and using field data for training is close to impossible. On the other hand, if simulation data are utilized for training, the mismatch between the simulation system and the practical system will cause fault location errors. To this end, this paper proposes a physics-informed data-driven fault location method. The data from a practical fault event are first analyzed to extract the ranges of system parameters such as equivalent source impedances, loading conditions, fault inception angles (FIA) and fault resistances. Afterwards, the simulation system is constructed with the ranges of parameters, to generate data for training. This procedure merges the gap between simulation and practical power systems, and at the same time considers the uncertainty of system parameters in practice. The proposed data-driven method does not require system parameters, only requires instantaneous voltage and current measurements at the local terminal, with a low sampling rate of several kHz and a short fault time window of half a cycle before and after the fault occurs. Numerical experiments and field data experiments clearly validate the advantages of the proposed method over existing data driven methods.

A parameter-free fault location method for cross-bonding cable based on ranging equations

With the increasing application of long-distance high-voltage cables using the cross-bonding grounding method in urban power grids, the effectiveness and accuracy of the single-phase short-circuit fault location method for cross-bonded cables have gradually gained attention. To reduce positioning errors caused by inaccurate or unknown line parameters, a fault location method independent of line parameters is proposed. Firstly, the changes in sheath circulating current before and after the fault occurrence are analyzed, and based on these changes, a criterion for fault identification is established to determine the approximate range of fault occurrence. Secondly, considering the three-phase electromagnetic coupling of cross-bonded cables, an equivalent model for single-phase short-circuit faults in cross-bonded cables is established based on the double-π model. The along-line voltage and current are calculated by deducing electrical quantities at the ends of the cable. Then, the fault location equations are formulated based on the fault section, and the trust-region algorithm is employed to solve for fault distances and unit-length parameters of the cable in each equation group. Finally, a cable fault model is built using the PSCAD/EMTDC simulation platform, and the influence of different factors on the fault location method is analyzed. The results show that the fault location error of the proposed method is around 0.2 %, demonstrating high accuracy.

Исследование точности определения места повреждения воздушных линий по данным от устройств синхронизированных векторных измерений различных классов и производителей

The technology of synchronized phasor measurements has been widely used in the Russian power system to analyze the parameters of steady-state electrical power modes and to record electro-mechanical transient processes. Issues on fault location based on synchronized phasor measurements have mainly been discussed in foreign publications. A significant drawback of most research papers on this issue is simplified modeling of both overhead lines and current and voltage measurement channel as well as digital filters of phasor measurement units (PMUs). The goal of this research is to develop a fault location algorithm based on synchrophasor measurements and to study its accuracy by using specialized equipment including a real-time digital simulator (RTDS), PONOVO current and voltage amplifiers and production-grade PMUs. A PMU-based double-ended fault location algorithm is developed using long-line equations and well-known electromagnetic transient theory concepts. Currents and voltage oscillograms of both overhead transmission line ends are modelled in the MATLAB/Simulink software package. These oscillograms are saved as COMTRADE files and played back using the RTDS hardware and all-in-one software package RSCAD. In addition, the study uses two production-grade PMUs, the first one is TPA-02, and the second one is a merging unit ENMU acting as a PMU, thus imitating PMUs at the line terminals. To time-align all the measurements and to aggregate PMU data frames, various auxiliary software such as PMU Connection Tester, and hardware is used. A double-ended fault location (FL) method utilizing synchrophasors under a fault has been developed. The method is based on an overdetermined system of nonlinear equations that describes physical processes in an overhead power line and can be applied under various fault types. An integrated study of the efficiency of the developed FL method has been conducted. FL errors have been computed using production-grade PMUs ENMU and TPA-02, along with the RTDS and other equipment. The authors have considered the case of configuring PMUs of different classes at the overhead line terminals, and different phasor reporting rates as well. The conducted experiments make it possible to reveal that the fault location errors do not exceed the thresholds imposed by the standard STO 56947007-29.120.70.241-2017 in 88 % of all the analyzed fault scenarios. The developed FL method makes it possible to achieve the accuracy required by regulatory guide in calculating the distance to the short circuit point in most of the cases examined. Based on the results of numerical experiments for various types of fault cases, it can be concluded that the PMU class and phasor reporting rate do not have a significant impact on the FL accuracy, provided that the fault duration is enough for the PMU filter to approach a steady output.

Location of Faults in Six Phase Transmission Line using a Neuro Fuzzy System

Fault location plays an important role in power systems. It is frequently used in transmission lines to reduce the system damage for growing electrical energy demand. However, the location estimation method itself is easy to be disturbed by different parameters and gives estimation errors. To solve this problem, this paper introduces a scheme that uses neuro fuzzy system (NFS) to locate all types of faults such as shunt faults, transforming faults, series faults and simultaneous faults in six phase overhead line (SPOL). This scheme has been performed on a 68 km, 138 kV, 60Hz, SPOL for all fault types by employing MATLAB software Simulink. Here, Haar wavelet transforms (HWT) are used to extract the current signals in order to evaluate the behavior and characteristics of higher frequency components. Then, the obtained HWT currents data are employed to construct the fault location scheme in SPOL based on NFS. The obtained experimental results confirm that by using the NFS, the maximum fault location error (MFLE) can be reduced by more than 10%. It can further reduce the maximum response time (MRT) for the operator to address the faults and ensure the power system reliability in the future. The test result executed in this investigation indicates that the NFS is resilient to wide changes in fault conditions, and it shows good performance and huge potential for location of faults in SPOL.

An impedance-multi-method-based fault location methodology for transmission lines connected to inverter-based resources

This paper is motivated by the growing penetration of Inverter-Based Resources (IBRs) in power systems and their impacts on fault diagnosis systems. Also, a motivating factor is the scarcity of works in the literature that evaluate the effects and provide solutions to impedance-based fault location in lines interconnecting IBRs to the grid. In this context, the performance of ten traditional impedance-based (one- and two-terminal) fault location methods is evaluated, and a multi-method methodology that minimizes the obtained fault location errors is proposed. To conduct the analysis and propose the methodology, the PSCAD software is used to carry out massive fault simulations on two systems with different voltage levels and connection topologies of IBRs to the grid. The results demonstrate that the proposed methodology significantly minimizes the fault location percentage errors, being a very promising proposal, especially for conditions in which communication channels between the line terminals are unavailable.

Многофакторное автоматизированное исследование методов определения места повреждения на модели воздушной линии электропередачи 500 кВ

Fault location is one of the main means of automation of electric power on overhead power lines. Well-timed elimination and organization of maintenance and repair work to put power lines into operation require high accuracy of fault location. Fault location methods based on the parameters of emergency mode using data of electronic (digital or optical) instrument transformers have been developed in Ivanovo State Power Engineering University (ISPU). The use of electronic transformers makes it possible to reduce the instrumental error of fault location due to accurate measurements of electrical quantities during short circuit, including the measurement of the derivative of the primary current. The aim of the study of fault location methods developed by the ISPU team is to evaluate the errors of these methods with a variation of many factors affecting the calculation of fault location in an automated mode using modern modeling tools. A multifactorial automated research of the fault location methods is carried out using a simulation model of an ultra-high voltage network in the Matlab + Simulink software package. One-sided and two-sided fault location methods based on the parameters of emergency mode developed in ISPU are chosen as the studied methods. In the research methodology presented in the article, the values of the factors affecting the measurement of fault location, including the parameters of the network element models, are changed using a program in the MATLAB language with parallel calculations performed on different processor cores. A technique for automated research of fault location methods has been developed including a model of an ultra-high voltage electrical network in Simulink and a simulation model control program in Matlab. More than 100,000 computational experiments have been carried out for each fault location method. According to the study, the influence of transient resistance is excluded, and the influence of the network frequency is practically absent in the two-sided method. The change in the parameters of power transmission lines and equivalent systems is less affected in comparison with the one-sided method. The Monte Carlo method of fault location algorithms has shown that the errors of one-sided method do not meet the requirements of PJSC «FGC UES» standards in less than 20% of cases, and the errors of the two-sided method under the same modeling conditions do not meet the requirements only in 1% of cases. The developed research methodology makes it possible to evaluate the accuracy of fault location methods when changing the set of factors influencing the measurement in an automated mode. The carried-out research of one-sided and two-sided fault location methods based on emergency mode parameters and data of electronic transformers has showed sufficient accuracy on the model of a 500 kV overhead power transmission line with changes in individual factors affecting the measurement of fault location and when randomly setting a set of parameters of the network model.

Extreme learning machine-based fault location approach for terminal-hybrid LCC-VSC-HVDC transmission lines

This paper proposes an Extreme Learning Machine-based fault location method to evaluate the DC transmission line faults of Terminal-hybrid LCC-VSC-HVDC systems. For this purpose, the voltage and current fault signals are firstly measured from the terminals of the hybrid HVDC system. Then, the high-frequency components of the input signals will be extracted and decomposed employing wavelet transform. In the next step, the energy of these extracted signals is calculated and provided to the extreme learning machine as intake train and test data. Finally, the exact location of the fault point will be determined using ELM. The proposed strategy is also applied to the same hybrid system using single-layer and double-layer neural networks, and the results have been thoroughly compared with ELM. The outcomes unequivocally indicate that by increasing the amount of DC filters in the transmission line, the average percentage error of fault location will be remarkably diminished. A ± 100 kV Terminal-hybrid LCC-VSC-HVDC system has been implemented and simulated via MATLAB software to assess the proposed method. It can be perceived that the ELM-based method not only works properly under various fault resistances, fault locations, and types of faults but also has significant superiority over the ANN-based approaches.

Adaptive Fault Locator for High-Voltage Transmission Lines Based on the Estimation of Power System Model Parameters

Abstract This paper presents an adaptive transmission line fault location method, which incorporates fault location devices at both line ends and utilises data import from a supervisory control and data acquisition system without strictly requiring data synchronisation. The developed method aims at achieving a higher degree of robustness, adaptiveness and accuracy. The adaptiveness is achieved by dynamic updating of mathematical models used on the basis of network-wide information, such as data on the state of circuit-breakers and apparent power at load and generation nodes. The robustness and accuracy are enhanced by incorporating two stages of identification of model parameters with the goal of reducing the decision variable space for the stage identifying fault parameters. Furthermore, in addition to utilisation of all measurements available at a particular substation, the developed method partially employs the measurements from the other end of the line by means of result cross-checks, but does not require a full data set, unlike deterministic-model-based methods. An optimisation-based approach, redundancy on the basis of extended measurement set, and cross-checks reduce the risk of fault location errors due to measurement errors or “voids” in the data available. Testing of the developed method demonstrates its accuracy and robustness in a wide range of pre-fault and fault regime scenarios, even when considering various pre-fault contingencies.

Remote fault detection and location of power fiber optic cable based on a logistic regression model

Abstract The current fiber optic communication network presents the characteristics of network scale, complexity, and efficiency, and the use of traditional means for the maintenance of power fiber optic cable has been greatly limited. In this paper, based on the characteristics of simple structure, convenient construction, strong randomness, strong sequence autocorrelation, and good iterative performance of chaos theory in a logistic regression model, a logistic-based remote fault detection and location system for power fiber optic cables is proposed. The fault location test is carried out through with TMS200 series fiber optic cable automatic monitoring management system and GIS method. The fault location error of the logistic-based fault detection method is less than ±3m, that of the GIS method is less than ±10m, and that of the TMS200 series cable automatic monitoring and management system is less than ±15. The comparison shows that this paper’s fault detection and location system is more accurate and can help maintenance personnel have a faster and more comprehensive understanding of the line situation. Realize the rapid repair work of faults, which provides great help to maintain the fiber optic cable lines.

Fault diagnosis in bipolar HVDC systems based on traveling wave theory by monitoring data from one terminal

This paper proposes a method for detecting, classifying and locating incident faults on transmission line (TL) of a bipolar HVDC system. This method is based on the traveling waves theory and uses the redundant discrete wavelet transform to filter voltage signals monitored at only one system terminal. The model represents the Brazilian HVDC system of the Madeira River, which is simulated in the Alternative Transient Program (ATP). Different fault scenarios are analyzed, being generated by varying type, resistance and fault location. Moreover, in order to make the simulation more realistic, the TL is modeled based on frequency dependent parameters. Thereby, the impacts of line parameter uncertainties and transient attenuation on the proposed method are analyzed. From the obtained results, it is concluded that the method correctly detects all fault types through the use of a self-adaptive detection threshold. Furthermore, it is verified that the self-adaptive threshold detects the fault times instants with an efficiency superior to the fixed threshold. In the classification step, all faults were correctly classified through rules elaborated based on the voltage variation level. Finally, the total average errors of fault location represents only 0.047% of the TL extension. Moreover, it is verified that fault location errors for pole:pole faults were inferior to those obtained for pole:ground faults, being the efficiency of the method inversely proportional to the fault resistance.

Analytical multi-section Bergeron model of transmission lines and application to accurate fault location for long HVDC lines

Line Bergeron model is widely adopted for various applications including line fault location. However, it models the line distributed series resistance using a very limited number of lumped resistors, resulting in modeling errors. For long HVDC lines, this modeling error will cause fault location errors. In addition, if high frequency components of measurements are adopted to mitigate the influence of the frequency dependent parameters, the modeling errors of the existing Bergeron model and the fault location errors will be further magnified. To this end, this paper proposes a multi-section Bergeron model to improve line modeling and fault location accuracy. First, the error of the existing Bergeron model is analytically derived to show its limitations. Then, with multiple Bergeron sections in series to well approximate the distributed series resistance, the analytical expression of the multi-section Bergeron model is proposed with rigorously derivations and proofs. Finally, based on the proposed multi-section Bergeron model, a novel fault location scheme for long HVDC lines is presented, where the 1-mode and high frequency components of measurements are utilized to minimize the impact of line frequency dependent characteristics. Numerical experimental results in both LCC and VSC HVDC systems show that the proposed method has higher line modeling accuracy and fault location accuracy than the existing method. The proposed multi-section Bergeron model can potentially be applied to other long transmission line related applications.

High precision improved double-ended travelling wave ranging technology for offshore DC cables

Aiming at the problem of fault location for offshore DC cables, this paper analyses the reasons why the double-ended method is more accurate than the single-ended method in DC transmission lines. We point out that the error in fault location on DC cables using the double-ended method mainly comes from the fact that the difference in wave speed between different segments is ignored. Therefore, based on the traditional double-ended method, this paper proposes an improved double-ended traveling wave ranging method which considers the difference in wave velocity and the actual situation of offshore cables connected in sections using flexible joint technology.

Differential equation fault location algorithm with harmonic effects in power system

About 80% of faults in the power system distribution are earth faults. Studies to find effective methods to identify and locate faults in distribution networks are still relevant, in addition to the presence of harmonic signals that distort waves and create deviations in the power system that can cause many problems to the protection relay. This study focuses on a single line-to-ground (SLG) fault location algorithm in a power system distribution network based on fundamental frequency measured using the differential equation method. The developed algorithm considers the presence of harmonics components in the simulation network. In this study, several filters were tested to obtain the lowest fault location error to reduce the effect of harmonic components on the developed fault location algorithm. The network model is simulated using the alternate transients program (ATP)Draw simulation program. Several fault scenarios have been implemented during the simulation, such as fault resistance, fault distance, and fault inception angle. The final results show that the proposed algorithm can estimate the fault distance successfully with an acceptable fault location error. Based on the simulation results, the differential equation continuous wavelet technique (CWT) filter-based algorithm produced an accurate fault location result with a mean average error (MAE) of less than 5%.

Fault location of flexible grounding distribution system based on multivariate modes and kurtosis calibration

Aiming at the problems of large fault location errors when the traditional traveling wave fault location is applied to flexible ground distribution systems. This paper proposed the fault location of flexible grounding distribution system based on multivariate modes and kurtosis calibration. Firstly, a disturbance signal is generated by putting a small resistor in parallel. This signal reaches the fault point and undergoes a sudden change, generating an aerial mode traveling wave signal. Secondly, it used the multivariate variational mode decomposition algorithm to decompose the aerial mode current and extracts the fault features. Then, the discrete kurtosis value is calculated for the highest frequency intrinsic mode function component. The moment of maximum kurtosis is the arrival time of the aerial mode current. Finally, it adopted the head-end detection device to calculate the fault distance. For the complex topology of the flexible ground distribution systems, the localization equation of the overhead line, cable line, and hybrid lines are studied, and the pseudo-fault points are excluded by adding auxiliary devices at the branch end. The simulation results demonstrate that the proposed method can accurately locate faults and is not affected by the fault's initial phase angle, transition resistance, and location.

Estimating the Error of Fault Location on Overhead Power Lines by Emergency State Parameters Using an Analytical Technique

Fault location on overhead power lines achieved with the highest possible accuracy can reduce the time to locate faults. This contributes to ensuring the stability of power systems, as well as the reliability of power supply to consumers. There are a number of known mathematical techniques based on different physical principles that are used in fault location on overhead power lines and whose errors vary. Fault location on overhead power lines uses techniques based on the estimation of emergency state parameters, which are referred to as distance-to-fault techniques and are widely used. They are employed in digital protection relay terminals and power-line fault locators. Factors that have a significant impact on the error of fault location on overhead power lines by emergency state parameters are design, manufacturing, and operation. The aim of this article is to analyze the existing techniques and to present a new analytical technique for estimating errors of fault location on overhead power lines by using emergency state parameters. The technique developed by the authors makes it possible to properly take into account a set of random factors, including various measurement errors of currents and voltages in the emergency state, which have a significant impact on the fault location on overhead power lines error. The technique allows one to determine more accurately the fault location and the size of the inspection area, which is necessary to reduce the time it takes to carry out emergency recovery operations. The proposed technique can be applied in fault locators and digital protection relay terminals that use both single-end, double- and multi-end sensing of currents and voltages in the emergency state.

On the Accuracy of Correlation Estimator Based Fault Location Methods in Transmission Lines via Polynomial Chaos and Regression Analysis

The electromagnetic time reversal (EMTR) method has recently shown a novel advantage in locating faults along transmission lines. Under the ideal condition for EMTR, the key parameters in the transmission line between the direct and reversed phases are assumed to be identical. Thus, the fault position can be pinpointed via the cross-correlation matching theory. However, due to natural and geographical causes, the parameters vary along the line; therefore, accurately obtaining the parameters is difficult. In this article, we first investigate the impact of uncertain parameters on the performance of EMTR-based fault location methods. It has been observed that the performance is insensitive to the variation of the parameters in the lossless case of transmission lines. But in the case of the overhead line above the lossy ground, a significant error in fault location is witnessed. So, under parameter uncertainty, a novel approach to finding the confidence fault interval is proposed, based on utilizing the polynomial chaos and regression analysis. A simulation case with uncertain parameters for different scenarios is presented to validate the performance of the proposed approach.

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

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

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%.