Fault Location Scheme Research Articles

A Fault Location Scheme for Active Untransposed Distribution Systems Using a Limited Number of Synchronized Measurements

This paper presents a fault location scheme for unbalanced and untransposed distribution systems which contain different types of distributed generation (DG). A general formula has been derived for any fault type using a limited number of synchronized measurement points. To avoid having to synchronize all the measurement points, the voltage and current measured locally at the DGs are processed locally to calculate the equivalent impedance of the DG at the non-fundamental frequencies. This is then used in the fault location process. The IEEE 34-bus feeder is simulated using the distributed parameter model for the lines and is used to validate the proposed scheme. Uncertainties associated with fault type, fault location, fault resistance, inception angle, noise in measurements and load profile are considered in the evaluation. The simulation studies demonstrate that the scheme can have a high accuracy and is robust.

A Literature Review on Methodologies of Fault Location in the Distribution System with Distributed Generation

In the last decade, with increasing power supply from distributed generation (DG) to the distribution system, the traditional passive radial distribution systems transformed into an active multisource system. The nature of fault location schemes designed for the distribution system has traditionally been based on unidirectional power flow assumptions, making them ineffective for a distribution system with a higher level of DG penetration. New grid regulations require DGs to remain connected to the system in the event of a fault to provide support to the grid and improve system reliability. This makes the fault location process important as the timely location of a fault speeds up the restoration process, which improves the system reliability. Herein, providing a comprehensive review of the available techniques for fault location in the distribution system with DG penetration is focused on. An analysis is given on the shortcomings of traditional protection methods when applied to DG‐integrated distribution systems. A comparative analysis is carried out in which the merit and demerit of each technique is assessed. A discussion on some other important technical issues arising due to DG integration, such as effects on the stability of the distribution system, is also given.

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

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

Data-Driven Fault Localization in Distribution Systems with Distributed Energy Resources

The integration of Distributed Energy Resources (DERs) introduces a non-conventional two-way power flow which cannot be captured well by traditional model-based techniques. This brings an unprecedented challenge in terms of the accurate localization of faults and proper actions of the protection system. In this paper, we propose a data-driven fault localization strategy based on multi-level system regionalization and the quantification of fault detection results in all subsystems/subregions. This strategy relies on the tree segmentation criterion to divide the entire system under study into several subregions, and then combines Support Vector Data Description (SVDD) and Kernel Density Estimation (KDE) to find the confidence level of fault detection in each subregion in terms of their corresponding p-values. By comparing the p-values, one can accurately localize the faults. Experiments demonstrate that the proposed data-driven fault localization can greatly improve the accuracy of fault localization for distribution systems with high DER penetration.

Time-domain based fault location for series compensated transmission lines without requiring fault type

Accurate fault location algorithms enable a quicker return to operation of faulted lines. The previously published fault location algorithms for series compensated transmission lines need the fault type and/or the compensator model to be known before fault location estimation. Thus, the accuracy of them is highly related to the fault type classification method and/or modelling of the compensator. This article suggests a fault location scheme for transmission lines compensated by series devices without requiring fault type based on synchronized instantaneous values collected from both ends of the line along with taking advantage of the distributed parameter line model in the time domain. The main advantages of this method are: (1) It not only determines faulty phases, but also estimates the fault location, simultaneously; (2) It is also independent on models of the series devices, so that the scheme is valid for transmission lines compensated by any series compensator. This paper examines the accuracy of the new algorithm for different fault situations with wide variations in system operating conditions in the presence of a Thyristor-Controlled Switched Capacitor (TCSC) and a Static Synchronous Series Compensator (SSSC). The results show that the fault type-classification and location accuracy of the method is high.

Precise Fault Location in Distribution Networks Based on Optimal Monitor Allocation

This article presents a novel fault-location method for unbalanced distribution networks in the presence of distributed generations. By utilizing the linear least square method, the candidate faulty lines are selected, and the injected fault currents are derived from the sparse voltage phasor measurements. According to the obtainability of the fault currents, two types of approaches are adopted for estimating the per-unit fault location. By taking advantage of the precise fault-location scheme, the actual faulted line and the accurate fault location are identified. Also, in order to compromise between the fault-location accuracy and the allocation costs, an optimal monitor-allocation algorithm is developed for determining the Pareto-optimal set of meter placements that have the minimal number of monitors to satisfy the requirements of fault-location accuracy. The proposed optimal allocation algorithm and the two types of fault-location approaches are validated on a modified IEEE 123-node test feeder using Matlab and Simulink.

Fault Location for Radial Distribution Network via Topology and Reclosure-Generating Traveling Waves

Fault location in distribution networks is difficult for multiple discontinuities, such as branches and junction points. This paper proposes a fault location scheme using network topology information and reclosure-generating traveling waves. Based on the topology, the circuit breaker closure-generating normal traveling waves (CNTWs) can be analyzed. When permanent faults occur, the circuit breaker reclosure-generating fault traveling waves (RFTWs) contain the information on fault position. The difference between the CNTWs and RFTWs, defined as reclosing superimposed traveling waves (RSTWs), is calculated. For RSTWs, their initial traveling waves are detected by wavelet transform. The time difference between the reclosing instant and the arrival instant of the reflected traveling wave of the fault point is employed to calculate the fault distance. Moreover, due to large numbers of branches, a fault distance may correspond to many sections. To determine the fault section, a database which contains the RSTWs induced by the faults occur in each section is built. The fault section can be identified by finding the most similar signals in the database by taking advantage of an improved dynamic time warping method. The simulation results indicate that the scheme can locate fault for distributed feeders regardless of grounding system type, load variation, and fault type.

A Wideband Single End Fault Location Scheme for Active Untransposed Distribution Systems

This paper presents a single end fault location scheme for distribution networks with distributed generation (DG). The high frequency transients generated when a fault occurs are used to locate the fault point. An equivalent circuit at high frequencies is derived for both inverter based and synchronous DGs. The voltages and currents measured only at the main substation are used in conjunction with the proposed DG model to create the fault location scheme. The distributed parameter line model is employed in the derivation to account for the line characteristics, e.g., inductive and capacitive mutual coupling and untransposed lines. The inverter based DG model is validated experimentally on a 400 V, three-phase system. The IEEE 34-bus feeder is simulated and used to evaluate the proposed scheme for different operating conditions, e.g., fault resistance and DG conditions. The extensive simulation studies show the accuracy of the proposed scheme with 95.3% of the test cases having an absolute error in estimation of less than 200 m.

Single phase fault diagnosis and location in active distribution network using synchronized voltage measurement

To ensure the safe operation of the active distribution network (ADN), accurate fault diagnosis and location are crucial to improve the reliability indices and reduce the outage time. This paper proposes a characteristic model-based method for the single phase to earth fault in the ADN system. Firstly, the characteristic model of the fault factor extracts the phasor distribution characteristics of the voltage and current along the distribution feeder line and estimates the current contribution of DG units to the fault point. Based on the minimum entropy theory, the solution of nonlinear characteristic model is transformed to a single-objective optimization of the characteristic entropy and the diagnosis criteria is formulated. Then, the two-stage fault location scheme for single phase fault is proposed. The fault diagnosis stage estimates the suspicious fault section to reduce the search area and the fault location stage locates the exact fault distance. The Fibonacci search algorithm is utilized for fault location to the optimize iterative and minimize the respond time. The proposed scheme is general for all DG types and overcomes the requirement of its individual model parameters. The proposed method is validated in the IEEE 34-bus distribution test system using the phasor measurement unit (PMU). Test results of the model-based diagnosis and location method can reveal accurate fault location and rapid response at different fault impedance and small time delay comparing with the radial basis function neural network (RBF), and wavelet neural network (WNN) method.

Novel Fault Detection and Localization Algorithm for Low-Voltage DC Microgrid

Accurate estimation of fault location is highly crucial for swift maintenance and early power restoration. Since faults in dc networks are time critical, this article proposes a new fault detection and localization scheme for a low-voltage direct current (LVdc) microgrid network. Low-resistance faults are detected by observing voltage across the inductor whereas high-resistance ground faults are identified by measuring ground current at the relay location. Thereafter, based on iterative method, fault location is estimated by comparing analytically derived fault current with the measured value of fault current. Genuineness of the suggested technique has been assessed by simulating various internal, external, and simultaneous faults on a typical LVdc microgrid network modeled in power system computer aided design/electromagnetic transients including dc (PSCAD/EMTDC) environment. The proposed method is capable of detecting and locating both low- and high-resistance dc faults without utilizing remote-end quantities. Subsequently, initial guess has minimal impact on the convergence and accuracy of the proposed algorithm. Comparative evaluation of the proposed technique with other techniques clearly proves its superiority in terms of better discrimination against external faults, rapid detection during internal faults, independency on the network topology, and higher accuracy for fault distance estimation against all types of internal faults.

Fault Localization Strategy for Modular Multilevel Converters Under Submodule Lower Switch Open-Circuit Fault

The modular multilevel converter (MMC) is an attractive option for high-voltage and high-power applications. Fault localization is one of the most important challenges for the MMC consisting of a large number of power electronic switches. Existing literature has not provided a complete fault localization strategy for the MMC under submodule (SM) lower switch open-circuit fault, which only considers the MMC in inverter mode and neglects the MMC in rectifier mode. This article proposes a fault localization strategy for the MMC under SM lower switch open-circuit fault, which is suitable for the MMC not only in inverter mode but also in rectifier mode. This article analyzes the MMC fault characteristics under SM lower switch open-circuit fault, which considers the MMC in inverter and rectifier mode, respectively. Based on two modes' common fault characteristic that the capacitor is charged all the time during the period when the arm current is positive, the faulty SM can be effectively located by the proposed fault localization strategy. The proposed strategy is not only implemented in simulation with professional tool PSCAD/EMTDC but also verified with a downscale MMC prototype in the laboratory. The results confirm the effectiveness of the proposed strategy.

Data-Driven Fault Location Scheme for Advanced Distribution Management Systems

There is now an increased interest among electric utility companies to implement advanced distribution management system (ADMS) software platform in their regular operational activities. ADMS provides smart grid functionalities, such as conservation voltage reduction, demand response, fault location, isolation, and service restoration (FLISR), etc. The ADMS platform improves power quality, increases reliability and resiliency, and manages the integration of distributed energy resources (DERs) effectively. This paper proposes a fault location scheme as a part of the FLISR program based on measurement from wireless sensors and smart meters deployed throughout the feeder. Sensors and smart meters use wireless sensor network and advanced metering infrastructure (AMI), respectively. The fault location scheme also considers the bi-directional power flow complexities with the integration of PV-based DERs at the edges of the grid. Initially, a modified depth first search is utilized to reduce the search space to find the faulty zone(s) bounded by two sensor buses; next, a voltage profile analysis is conducted in the specified zone(s) to find the actual faulty section(s). To demonstrate the robustness, the entire algorithm is tested in a utility scale feeder with various loading, DER penetration, and fault resistance condition using Monte-Carlo method.

Fault location in multilateral distribution network with electric vehicle charging load

AbstractIn a multilateral distribution network, faults at different locations can generate the same voltage and current at the substation; hence, the calculated fault location can correspond to several places in the network. To avoid this major problem, a two‐terminal travelling wave‐based fault location method is presented in this article, which at first identifies the faulted lateral in the distribution network and then estimates the exact fault location. The proposed fault location scheme uses wavelet energy entropy of the recorded three‐phase current signals and the magnitude of ground mode component wavelet modulus maxima (WMM) for fault detection and fault type identification in the network. After that, the faulted lateral identification followed by the exact fault location is performed using the aerial mode component WMM of the fault‐generated current transients. Since the integration of electric vehicle (EV) charging load is increasing day by day to the distribution network, the performance of the proposed algorithm is tested with EV charging load along with distributed generation integrated into the distribution network. Modeling and simulation of the distribution network and EV load are performed in MATLAB/SIMULINK. The simulation results show that the proposed method can accurately locate fault under different operating conditions.

Negative-Sequence Network Based Fault Location Scheme for Double-Circuit Multi-Terminal Transmission Lines

The fault resistance and infeeded currents from tapped transmission lines are the two main challenges to establish correct fault location estimation in multi-terminal transmission lines. Also, fault location estimation in double-circuit lines is more complicated than single-circuit lines due to the effect of mutual coupling and inter-circuit faults. This paper proposes a negative-sequence network-based method to estimate the fault location of double-circuit multi-terminal transmission lines. In the presented method, signals are measured in the relay location and then, communication links are not required as it uses only one end measurements. Also, in conventional distance relays, six elements are needed to calculate the fault location in all types of faults. Furthermore, in this method, by using only one element for each transmission line, accurate fault location can be estimated. Also, high fault resistance, mutual coupling, and infeeded currents from tapped transmission lines do not have impact on the performance of the presented scheme. To investigate the effects of the line shunt capacitances on the proposed method, a PI model of the transmission lines is used in all the investigations. Simulation results carried out using MATLAB software indicate that the proposed scheme is able to produce excellent performance for the fault location estimation.

Accurate fault location and faulted section determination based on deep learning for a parallel‐compensated three‐terminal transmission line

Parallel flexible AC transmission systems (FACTS) devices affect the performance of protection relays and conventional phasor-based fault location schemes in transmission lines. This study focuses on both multi-terminal and parallel-compensated lines, not investigated simultaneously in previous works. An algorithm based on deep neural networks is proposed for fault location in a three-terminal transmission line with the presence of parallel FACTS device. The line model and fault occurrence are simulated in SIMULINK and features are extracted from voltages at the three terminals by wavelet transform. The generated features are used to train a deep neural network which determines faulted line section and fault distance simultaneously. The adopted intelligence-based approach has the advantage of not requiring pre-knowledge of line specifications, FACTS devices modelling and the uncertainty in compensator parameters. A large number of fault scenarios are investigated. The faulted section is recognised correctly in 100% of test cases. The algorithm performance is acceptable for both symmetrical and unsymmetrical fault types, small fault inception angles and high fault resistance. The accuracy of fault location is improved compared to previous schemes (total mean error of 0.0993%). The proposed algorithm provides an accurate, fast and robust tool for fault location in parallel-compensated three-terminal transmission lines.

A new single end wideband impedance based fault location scheme for distribution systems

This paper proposes an improved impedance based fault location scheme based on system analysis at non-fundamental frequencies. The fault is treated as a voltage source that injects high frequency components into the system and the analysis is carried out using these injected components. The proposed method only requires local measurements at the substation and therefore is classified as a single end method. The new contribution is that the proposed method uses the distributed parameter line model to account for inductive and capacitive effects of the line. It has been evaluated on the IEEE 34-bus feeder which is based on an actual distribution system which has the typical features such as non-homogeneous feeder sections, asymmetrical line configurations, unbalanced loads and single and three-phase laterals. The fault point, fault resistance and fault inception angle have been varied to check their influence on the accuracy of the method. The simulation results demonstrate the accuracy of the proposed method where for most cases, the error in fault location is less than 50m.

High-speed fault detection and location in DC microgrids systems using Multi-Criterion System and neural network

This paper presents a new protection method for LVDC ring-bus microgrid systems based on Multi-Criterion System (MCS) and Neural Network (NN). The proposed method aimed at high-speed detecting line-to-ground (LG) and line-to-line (LL) low impedance faults without using a definite threshold of differential current by using specific rules and multi-criterion system. MCS protection showed speed and accuracy compared to differential protection. Also, NN estimated fault location in percent of line length acceptably as a secondary controller. In order to evaluate the reliability and the enforceability of fault detection and location schemes, simulated network and protection algorithms are implemented and tested in laboratory-scale. The implementation results indicate that the MCS and NN protection scheme can consistently detect and estimate fault locations in the order of a few milliseconds. To reach this goal, a loop type LVDC microgrid with proper power electronic equipment like solid-state bidirectional breakers and the multi-level inverter is fulfilled.

A Novel Fault-Location Algorithm for AC Parallel Autotransformer Feeding System

In general, an autotransformer (AT) is used to improve the voltage sag and inductive interference in power lines and communication lines in the Korean ac electric railway feeding system. In particular, the Korean AT feeding system has a different configuration compared to those of the other countries, such as Japan or France; therefore, it has certain distinctive characteristics. However, a fault locator imported from the other countries has been used in Korea, and the settings of these equipment should be modified and reflect the distinct characteristics of the Korean AT feeding system. Thus, the development of a novel fault-location scheme for the Korean railway system is required. Herein, we analyzed the fault current and developed a specific relationship for use in our new algorithm. We presented the current magnitude of each branch, expressed by the boosting current of the ATs; further, the novel fault-location scheme using this relationship is developed. The novel scheme performance is verified through power system computer aided design/electromagnetic transients including DC (PSCAD/EMTDC) and the field measured data.

Fault Location Method in Power Network by Applying Accurate Information of Arrival Time Differences of Modal Traveling Waves

Faults may be generated in power networks as a result of bad weather, human activities, or some other factors. The complex structure of power network adds to the difficulty of fault location (FL). This paper presents a novel FL scheme by utilizing the information of the time differences of arrival (TDOAs) of modal traveling waves (MTWs) asynchronously sampled in the network. First, the fault area is determined by searching the minimum TDOA of MTWs. Then, by applying the fictitious fault point method in the fault area, the minimum accumulated difference is used to detect the fault line. Finally, the accurate FL is estimated by solving the objective function of the absolute distance between the FL and multiple FL candidates. Various simulations are carried out in the IEEE 30-bus system. The calculation results demonstrate that the method is not affected by fault impedance, inception angle, location, and noises to a certain extent.

PMU Based Fault Detection in 14 Bus System

Accurate location of a fault on a line is extremely important to restore the parameters line in the shortest time as possible, which directly affects the operational cost and system reliability. This paper presents an accurate and fast strategy for fault location based on well-known state estimation method. The proposed method employs PMU measurements records line parameters during the fault (before the circuit breakers open). Those measurements are used for determination of the fault currents flowing on the faulted line and locating the fault using Weighted Least Squares (WLS) estimator. The proposed method reduces the required number of measurements for the solution of the fault location problem by making use of the fast refresh rates of the PMUs.