Faulted Line Section Research Articles

A Study on Fault Localization Method of Three-Terminal Multi-Section Overhead Line–Cable Hybrid Line Using MEEMD Combined with Teager Energy Operator Algorithm

An improved fault localization method combining total aggregate empirical modal decomposition (MEEMD) and Teager energy operator (TEO) is proposed to address the fault localization issue of three-terminal multi-segment overhead line–cable hybrid transmission lines. This method solves the fault localization problem caused by wave impedance discontinuity in hybrid lines. First, the MEEMD algorithm, which improves modal aliasing, and the Teager energy operator, which reflects transient energy changes, are combined for the accurate detection of faulty traveling wave heads. The fault line section determination condition within the fault branch is used to determine the overhead line section or cable section where the fault is located after determining the faulty branch line. This condition is based on the time difference between the initial traveling wave of the fault arriving at each end measurement point and the T-node. Ultimately, the fault distance is determined using the double-ended traveling wave technique. By combining PSCAD and MATLAB for simulation verification, the accuracy of the ranging method is compared and analyzed, and the results show that the method is able to ensure the accuracy of ranging at different fault locations and transition resistances. Additionally, the localization error is basically kept within 30 m, which significantly improves the accuracy of fault localization.

The online monitoring method of single-phase grounding fault in medium voltage distribution network based on multi-measuring point information

To reduce the error of single-phase ground fault and improve the security and stability of distribution network operation, an online monitoring method for single-phase ground fault in a medium voltage distribution network based on multi-measuring point information is proposed. Based on the analysis of single-phase grounding transient characteristics, the fault location is determined from the information of multiple measuring points according to the characteristics analysis results to realize the fault subsection location, identify the fault line section, and improve the location accuracy. Based on the fault location results, fault monitoring is realized through the “four-in-one” intelligent distribution terminal. The experimental results show that the accuracy of the monitoring results of this method is kept above 95%, and the monitoring error value of grounding fault is kept at about 1%, so the monitoring results have high reliability.

A Fault Location Identification Technique for Active Distribution System

Impedance based fault location schemes using substation measurements are becoming absolute due to the introduction of distributed generation and islanding-mode operating capability of distribution system (DS). In this article, a new fault location algorithm is presented for active distribution systems using microphasor measurement units (μPMU) and smart meter (SM) data. The line current data obtained from the μPMUs in the DS are exploited to divide the system into different zones. To identify the faulted zone, a fault zone identification parameter is devised based on the pre and during fault positive sequence current injection data recorded in the μPMUs. Next, fault location analysis is limited to the identified zone to reduce the computational complexity. To locate the fault within the identified zone, the work proposes two parameters for the identification of bus nearest to fault (BNF) and faulted line section connected to the identified bus. The scheme does not require the information about the type of ground faults and is applicable to balanced, unbalanced, grid connected and as well as islanded distribution systems.

A novel fault location method for hybrid lines based on traveling wave

In this paper, a novel fault traveling wave-based location method for hybrid lines is proposed. According to the refraction characteristics of fault traveling wave (TW) at junction nodes, the node ratio coefficient value Q is defined based on the amplitude of traveling wave. Then, by comparing the Q values of junction nodes and fault points, a fault section identification principle is proposed to determine the fault line section for hybrid lines. After identification of fault line section, a double-ended fault location method is revised via adding the location compensation factors to mitigate the effect of traveling wave velocity changes on fault location for multi-section hybrid lines. Additionally, considering the detection problems of arrival time for TW signals, the extreme-point symmetric mode decomposition (ESMD) method and Teager energy operator (TEO) are proposed. The ESMD method is applied to decompose the sampled fault traveling wave signals into several intrinsic modes to filter out the fundamental frequency and low frequency signals. The TEO is employed to track the characteristics of TW signals. Effectiveness of the proposed method is validated in PSCAD. Results show that the ESMD-TEO can detect TW signals effectively, and the proposed fault location method can determine the fault line section and locate fault positions correctly.

Performance Comparison of Impedance-Based Fault Location Methods for Transmission Line

Electric transmission lines play a very essential role in transmitting power energy from generation centers to consumption regions. They can be exposed to fault occurrences due to various reasons, such as lightning strikes, malfunction of components, and human errors. Since fault is unpredictable, a fast fault location method is required to minimize the impact of fault in power systems. This paper presents a research work for comparing the performance of the impedance-based fault location methods, in which the impedance parameter of the faulted line section is calculated as a measure of the distance to the fault. To evaluate the capability of the methods for correctly detecting and locating the fault locations, comprehensive simulation results are carried out. This computation is based on modeling and simulating a three-phase 220kV overhead transmission line in the Matlab/Simulink software. Short circuits which occur in various fault resistances and locations along the transmission line are emulated to investigate several case studies and the accuracy of fault location determination is calculated to compare the performance among these fault location methods.

Field experiment using transient energy method to locate a single-phase to ground fault

Distribution networks in China and several other countries are predominantly neutral inefficiently grounding systems (NIGSs), and more than 80% of the faults in distribution networks are single-phase-to-ground (SPG) faults. Because of the weak fault current and imperfect monitoring equipment configurations, methods used to determine the faulty line sections with SPG faults in NIGSs are ineffective. The development and application of distribution-level phasor measurement units (PMUs) provide further comprehensive fault information for fault diagnosis in a distribution network. When an SPG fault occurs, the transient energy of the faulted line section tends to be higher than the sum of the transient energies of other line sections. In this regard, transient energy-based fault location algorithms appear to be a promising resolution. In this study, a field test plan was designed and implemented for a 10 kV distribution network. The test results demonstrate the effectiveness of the transient energy-based SPG location method in practical distribution networks.

Hierarchical faulted line section location method for low‐voltage active distribution network considering information distortion

Distortion of fault monitoring information is an important factor that affects the accuracy of faulted line section location in low-voltage active distribution networks (ADNs). This paper proposes a faulted line section location method that considers the layered solution for monitoring information distortion, to improve the accuracy and efficiency of fault location in low-voltage ADNs. A multi-target fault section location optimization model that considers information distortion, multipoint faults, and multiple information distortion types is formulated. A combination of information distortion factors is introduced to represent various types of information distortion and to transform the original optimization model into an unconstrained 0-1 programming problem. A hierarchical fault location algorithm for segmenting the distribution network is designed to solve the low accuracy and efficiency of direct solutions for fault location models resulting from a large number of active distribution line sections. Simulation results show that the fault location method considering information distortion effectively guarantees the accuracy and solution efficiency of faulted line section location of low-voltage ADN.

Identification of faulted line section in microgrids using data mining method based on feature discretisation

Identification of faulted line section in microgrids using data mining method based on feature discretisation

High-impedance ground faulted line-section location method for a resonant grounding system based on the zero-sequence current’s declining periodic component

The probability of single-phase high-impedance faults (HIFs) in a resonant grounding system is high, and the existing fault detection and line-section location methods have drawbacks such as low accuracy and implementation difficulties. In this paper, an efficient method based on the zero-sequence current’s declining periodic components is presented to locate a high-impedance ground faulted line-section for resonant grounding systems. It analyses the parallel resonance process when a single-phase HIF occurs in a resonant grounding system. The distribution characteristics of the declining periodic component of the zero-sequence current at the fault point are studied. Moreover, we indicate that the zero-sequence current’s declining periodic components upstream and downstream of the fault point have large differences in phase. By utilizing this feature, a novel high-impedance ground faulted line-section location method is proposed. This method uses feeder terminal units (FTUs) to obtain the declining periodic components in phase based on the extended Prony method and a distribution automation master station to estimate the transition resistance; then, the protection criterion established by using the phase difference and fault resistance can be applied to identify the fault line-section. Based on a real-time digital simulator (RTDS) and the FTU developed with a faulted line-section location function, the proposed method is verified. The experimental results show that the scheme has good feasibility.

Location of Single Phase to Ground Faults in Distribution Networks Based on Synchronous Transients Energy Analysis

As a result of small fault current, high level of noise and a large penetration of distributed generators (DG), in the neutral non-effectively grounded medium-voltage (MV) distribution networks, it is quite difficult to locate the faulted line section for single phase to ground faults. In this paper, using a technique based on synchronized measurements in distribution networks, a fault location method based on the analysis of the energy of the transient zero-sequence current in the selected frequency band (SFB) is proposed. The equivalent impedance of the distribution network with lateral branches is studied with an equivalent network, and the phase-frequency characteristics of the equivalent impedance are analyzed. The SFB, within which the transient energy of the faulty line section is larger than that of the healthy line sections is determined. A combined fault-section location criterion is proposed and the implementation scheme is illustrated with the distribution level phasor measurement units. Numerical simulations of the IEEE 34 node system and the field experiments of a 10kV distribution network validate the feasibility and effectiveness of the proposed method.

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.

Fault location of transmission lines connecting with short branches based on polarity and arrival time of asynchronously recorded traveling waves

Due to complex reflection and refraction at line terminals, traditional single-end traveling wave (TW) fault location (FL) cannot be directly applied to transmission lines connecting with short branches. This paper presents an improved single-end TW FL method for this special case. Three TW recorders are required to be mounted at local, middle and remote terminals of the transmission line but accurate synchronous sampling is not required. In the proposed method, combined with the defined polarity coefficients of current TW wave fronts (WFs), the absolute difference of the time differences of arrival (TDOAs) of the modulus TWs at both terminals is firstly utilized to determine whether the fault occurs in the transmission line. If the fault is detected in the transmission line, the fault line section can be then determined by the ratio of the TDOAs of the modulus TWs recorded at both terminals. Finally, the TDOAs of the first two WFs at the three TW recorders are calculated and compared with the theoretical ones to determine the source of the second WF. The corresponding single-end accurate FL formula is selected to pinpoint the fault. A simulation model of a transmission line connecting with short branches is constructed by PSCAD/EMTDC. Various faults are simulated to verify the proposed FL method. The calculation results demonstrate that the method is not affected by FLs, impedances, inception angles, noises and longer lines to a certain extent.

Fault detection and location algorithm for DG‐integrated distribution systems

The overcurrent protection on the traditional distribution system uses local measurements and settings as a basis for decision-making. However, connection of multiple distributed generators with different short-circuit characteristics makes the local measurements unpredictable, leading to possible loss of protection coordination. In order to solve this problem, this study proposes an algorithm that achieves its protection function through load flow and sensitivity calculations based on voltage measurements. The algorithm is built on a modelling approach that splits the distribution network into a series of overlapping protection zones. The overlapping feature is realised logically through peer-to-peer communications between intelligent agents located in adjacent zones. A sensitivity-based electrical signature was identified that is generated when a fault occurs within a zone. Simulation results show that the proposed protection algorithm is able to identify the zone in which the fault has occurred and the specific faulted node or line section in that zone. The fault current contributions, or no contributions, of the distributed generators (DGs) do not impact the operation of this algorithm.

Power line signalling based earth fault location

Fault location in power networks is important as accurate information about the faulted line section expedites system restoration following a fault occurrence. A number of fault location methods have been proposed. Methods based on injecting a signal into the network and tracking it along the feeder appear to have received limited attention. In this study, fault location methods based on network signalling are examined. Two different types of approaches are presented. The first one is based on injection on a very low-frequency band, whereas the second one is based on utilising modern modulation technologies on low-frequency band, under 500 kHz, implemented on software-defined radios. The simulation results indicate the capability of the proposed methods in determining the location of a single phase-to-earth fault in medium-voltage distribution networks.

Voltage-Sag-Profiles-Based Fault Location in High-Speed Railway Distribution System

Operation parameters of the high-speed railway distribution system can be obtained from remote terminal units installed in box-type substations. Therefore, the voltage sag profiles may be utilized for fault location. This paper proposes a novel strategy for fault location in a high-speed railway distribution system by measured voltage data of existing box-type substations. The proposed method makes use of the difference between the calculated voltage and measured voltage at the end of the lines to locate the fault. Assuming that the fault occurs at any possible box-type substations along the lines, the faulted line section is identified with the defined difference sequence, and then the exact fault location can be obtained with a searching procedure in the identified fault section. Considering the effect of equivalent capacitance, each line section is modeled with the π model to improve accuracy of fault location. The validity of the proposed method is tested extensively in the simulation model of a real high-speed railway distribution system. The proposed method is not affected by fault type and fault resistance. Furthermore, comparing with the offline detection method of underground cables, it does not need any additional devices and will not interrupt the system operations.

Fault analysis in TCSC-compensated lines using wavelets and a PNN

This paper describes an algorithm to detect, localize and classify fault events in overhead transmission lines compensated with a thyristor-controlled series capacitor (TCSC). During a fault event, a complex pattern of traveling wave reflections and refractions is generated at the point of fault inception. The proposed algorithm uses the discrete wavelet transform combined with a probabilistic neural network to analyze all this information and determine whether a fault condition exists in the line, the fault type and also the fault distance. In order to assess the algorithm performance, several studies were carried out under varied conditions. The obtained results demonstrate that the algorithm accuracy for calculating the fault distance is smaller than 1% of the total line length, and a 100% efficiency for determining the fault type. The algorithm is also immune to harmonic interaction due to low-frequency harmonics generated by the TCSC. A comparative advantage over previous algorithms for TCSC-compensated transmission lines is the fact that the proposed algorithm not only identifies the faulted line section but also localizes accurately the distance to the fault, using only measurements at one end of the line.

Control and protection sequence for recovery and reconfiguration of an offshore integrated MMC multi-terminal HVDC system under DC faults

A comprehensive process of the control and protection against a DC fault in a voltage source converter (VSC) based high-voltage direct current (HVDC) system typically includes fault detection, fault isolation and system recovery. Regarding an offshore wind farm (OWF) integrated modular multilevel converter (MMC) based multi-terminal HVDC (MTDC) system with two control paradigms, i.e. master-slave control and droop control under DC faults, this paper presents the fault isolation, including the isolation of the faulted line section, with detailed control and protection sequence, which would be useful for practical engineering. The control and protection sequence at the system recovery/reconfiguration phase is comprehensively investigated, which includes: (1) when to start the recovery/reconfiguration control; (2) the sequence between deblocking the MMCs and reclosing the AC circuit breakers (AC CBs); and (3) the recovery sequence of each HVDC terminal. Based on the analysis of the system characteristics, a preferred recovery/reconfiguration scheme is proposed. Simulation results on the real-time digital simulator (RTDS) validate the proposed scheme and demonstrate the advantages through comparison with a different recovery sequence. The impact of transient and permanent DC faults on the system recovery/reconfiguration control is discussed. In addition, the recovery/reconfiguration control of the MTDC in radial and meshed topologies is compared and demonstrated. Based on the analytical and simulation studies, a general guideline on the recovery/reconfiguration control of MMC MTDC systems is proposed.

An Automatic Faulted Line Section Location Method for Electric Power Distribution Systems Based on Multisource Information

This paper presents an automatic faulted line section location method for distribution systems. It can be divided into two parts: faulted line section location method for medium-voltage distribution feeders and faulted area identification technique for low-voltage distribution systems. In the first part, an adjacency list that shows the adjacency relationship and status of fault indicating devices is developed. Then, an iterative search technique is devised to traverse the adjacency list to determine the faulted line section. In the second part, a relational table that shows the association relationship between smart meters, meter boxes, and distribution transformers is developed. Based on the table and the voltage of smart meters received from the customer electric information acquisition system, the faulted area can be located. Several test cases studied in a real distribution system demonstrate the effectiveness of the proposed method.

Fault Location Using Local Mean Decomposition on Traveling Waves with Three Current Measurements in an Overhead Conductor

A fault-location scheme based on local mean decomposition on traveling waves with three current measurements in an overhead conductor is presented herein. In the fault-location scheme, local mean decomposition is used to detect the arrival time of the initial traveling wave at each measurement. To obtain more accurate wave velocity, a third Rogowski coil current transformer is used to measure the fault current in the midway of a transmission line besides a couple of measurements used by the two-ended traveling-wave method at both its ends. The faulted line section can be identified by comparing the phase angles of the measured current data at its two ends; wave velocity can then be calculated by the ratio of the length of the non-faulted line section to the time that the fault wave travels through this line section. The proposed scheme can reduce the errors of previous methods on wave velocity determination. After wave velocity is determined, the fault distance can be calculated according to the two-ended traveling-wave method. The proposed fault-location scheme is tested by many simulations, and the results demonstrate it has higher accuracy than those using wavelet transform and Hilbert–Huang transform.

Complete power distribution system representation and state determination for fault location

<p>The impedance-based approaches for fault location in power distribution systems determine a faulted line section. Next, these require of the estimation of the voltages and currents at one or both section line ends to exactly determine the fault location. It is a challenge because in most of the power distribution systems, measurements are only available at the main substation. This document presents a modeling proposal of the power distribution system and an easy implementation method to estimate the voltages and currents at the faulted line section, using the measurements at the main substation, the line, load, transformer parameters and other serial and shunt connected devices and the power system topology. The approach here proposed is tested using a fault locator based on superimposed components, where the distance estimation error is lower than 1.5% in all of the cases. </p>