Wide-area Fault Location Research Articles

A Robust Wide-Area Fault Location Method for Transmission Lines With Uncertainties in Measurements and Network Parameters

A Robust Wide-Area Fault Location Method for Transmission Lines With Uncertainties in Measurements and Network Parameters

Generalized wide-area fault detection and location algorithm for transmission system based on optimal PMUs allocation

The transmission system is one of the three major parts besides the generation and distribution systems. Transmission system protection requires a vital especially development it involves in modern wide-area systems. This paper suggests a generalized robust fault detection and location algorithm established on the optimally allocated phasor measurement units (PMUs). The optimum allocation of PMUs ensures the entire observability of all transmission lines, that are included within the zones of protection. The generalized fault detection and location algorithm is based on the roots deduced from the basic transmission line model under normal operation. The algorithm enables to detection of faults closed to buses equipped with PMUs and high impedance single line to ground faults. The algorithm is characterized by generality and independent variable system dynamics. The proposed algorithm can detect simultaneous faults of any type with a high degree of accuracy. To validate the developed algorithm, it is utilized in the IEEE 14-bus system. The simulation study is conducted using Matlab/Simulink® software package. Different fault types are modeled under various fault resistances. The modeled fault cases prove the security of the developed algorithm against external faults with a high degree of dependability in the case of internal faults.

A Generalized Closed-From Solution for Wide-Area Fault Location by Characterizing the Distributions of Superimposed Errors

Wide-area fault location (WAFL) refers to the estimation of fault distance on the faulted line using PMU data. A system of linear equations is formulated for WAFL, taking advantage of both voltage and current synchrophasors. This results in a generalized closed-form solution for the fault distance using the weighted least-squares method. The main contribution of the letter is the rigorous derivation of the equation weights based on the statistical distributions of the superimposed errors, i.e., the differences between the errors of the corresponding pre- and post-fault synchrophasors. The method's effectiveness, robustness against different factors, and superiority over existing methods are demonstrated by extensive simulations and comparison studies conducted on the IEEE 39-bus test system.

An advanced wide-area fault detection and location technique for transmission lines considering optimal phasor measurement units allocation

The transmission system plays a vital role in the electric power system as it links load centers with power generation and, so, it is mandatory to protect this system from any abnormal conditions. This paper proposes a novel reliable fault detection and location technique based on optimally allocated phasor measurement units. The optimal phasor measurement units allocation guarantees the full observability of the system including all transmission lines, which are impeded in the protection zones. The proposed fault detection and location technique depends on the measured positive sequence components. The proposed technique has essential advantage due to its generalization to be valid for different areas’ sizes and configurations. The detection technique relies on calculated admittance, while the fault location is independent on fault resistance. For validation of the proposed technique, it is applied on the IEEE 14-bus system simulated using Matlab/Simulink® software package. Various faults are simulated considering fault resistance. From the simulated fault cases, the proposed technique proves its security against external faults and the dependability with internal faults.

Wide area fault location on transmission systems using synchronized/unsynchronized voltage/current measurements

Wide area impedance-based fault location methods use global positioning system (GPS) for pinpointing the fault position. GPS signal loss occurs repeatedly in power system because of slow communication link or lack of synchronized sampling infrastructure that makes synchronized measurements unavailable in some parts of the grid. To overcome the grid synchronization problem this paper presents a fault location method that integrates synchronized and unsynchronized current and voltage measurements in a system of equation form. In this system the magnitude of measurements is considered for all measurements and the phase angle is considered only for synchronized measurements. On the other hand, any type of measurements (current and voltage) which is done synchronized or unsynchronized can be integrated in the developed system. The integration of GPS synchronized and unsynchronized measurements prevents the GPS signal loss to affect the fault location problem, while many of the previous methods are not applicable under these conditions. Then the formed system is solved with the aim of finding the location of fault utilizing an iterative approach. The line distributed parameter model is used in this paper, which provides more accurate results nearer to real values. The proposed method is validated by WSCC 9-bus and IEEE 39-bus test systems which reveal accurate estimation even in conditions that the GPS signal is not accessible.

Robust Wide Area Fault Location Considering Network Parameters Error

Network parameters error may seriously affect the accuracy of fault location results, even making them unacceptable in extreme cases. This paper proposes a new method that incorporates these errors in wide area fault location problem using phasor measurement units to estimate inaccurate network parameters employing robust state estimation. Our proposed method is composed of two stages. The first stage or the primary stage provides an initial point for the second stage, which is the main contribution of this paper. Additionally, the set of measurements contaminated with bad data could be obtained from the first stage, and its intersection with leverage measurements are then eliminated from the measurement set before feeding it into the second stage. Finally, fault point and faulted line parameters are estimated by the main (second) stage of the method. The proposed method has been applied to two test systems, namely Institute of Electrical and Electronics Engineers (IEEE) 14-bus and IEEE 57-bus systems, to evaluate its accuracy. Simulation results indicate high accuracy and consistency of the proposed method.

Fault Location Schemes for Complex Power Grid Based on Multidimensional Information Fusion

Fast and accurate fault location in complex power grid is crucial to ensure the safe operation of power grid. It is inevitable that fault location is not merely in single transmission line but in complex power grid. This article first describes the correlation properties of multidimensional fault characteristics in complex power grid and reveals the relationship between the multidimensional fault characteristics and the fault distance. Then the optimized clustering analysis algorithm is presented to realize rapid and accurate identification of the fault area based on the multidimensional characteristics of measuring points. All the measuring points are divided into four categories: fault area, fault boundary region, fault transition region, and nonfault region. Location zone is constructed by fault region and fault boundary region. Finally, to get fault location results and fault occurrence time, linear equations are established by correlation properties of spatiotemporal information in location zone and solved by the least square method. At the same time, the applicability and reliability of the proposed method are analyzed. The IEEE 30-Bus System and IEEE 57-Bus System are built in PSCAD/EMTDC software. Compared with the existing method, the positioning accuracy of the proposed method is improved by 70.62%. Large number of simulation results show that the proposed method of wide-area fault location has higher accuracy and adaptability.

Wide-Area Backup Protection Scheme for Transmission Lines Considering Cross-Country and Evolving Faults

Wide-area fault detection and location for cross-country and evolving faults have not been discussed before in the open literature. This paper presents an innovative wide-area backup protection scheme for untransposed transmission lines considering cross-country and evolving faults. Synchronized voltages and currents measurements in the phase domain are used for fault detection and location. The proposed scheme can distinguish transmission line faults from other external faults or different operating conditions. The faulty line is correctly identified, and the locations of all fault types including cross-country and evolving faults are estimated precisely. The proposed scheme is investigated under different fault locations, fault resistances, fault types, and fault inception angles. In addition, the influence of transmission line parameter errors and synchronization errors on the proposed scheme is investigated. Extensive simulation studies are applied to New England 39-bus test system, and the simulation results prove that the proposed scheme yields better performance for all simulated cases.

Optimal placement of voltage measurements for wide area fault location observability considering the uncertainty of network parameters

This paper proposes an optimization method based on genetic algorithm (GA) to determine the number and location of phasor measurement units (PMUs) in order to wide area fault location based on voltage measurement. In the practical condition, due to the uncertainty of network parameters including measurement errors and inaccuracy of line parameter values, the estimation of the fault location may be not accurate. Therefore, the proposed method has been developed to determine the number and location of PMUs in order to achieve an acceptable accuracy with required reliability. Since the number and location of PMU depends on the fault location method, a new fault location method has been developed with minimum required number of PMUs. The new method can determine the fault location by measuring from one side of the fault point instead of two sides. Therefore, the number of required PMUs is minimized at comparison to previously presented methods. The weighted least-square (WLS) method is used to solve the fault location problem by minimizing the measurement errors. To consider unsynchronized condition of measurements, the formulation has been modified using only the magnitudes of voltage measurements. Finally, the method has been applied on New England 39-bus test system, and the results show the efficiency of the proposed PMU placement and fault location methods in the network with the uncertainty of parameters.

WITHDRAWN: WIDE AREA PROTECTION AND FAULT LOCATION: REVIEW AND EVALUATION OF PMU-BASED METHODS

WIDE AREA PROTECTION AND FAULT LOCATION: REVIEW AND EVALUATION OF PMU-BASED METHODS - Withdrawn on 26th October 2018

Wide‐area fault location method considering gross measurement errors

In this study, a wide-area fault-location (FL) method for power transmission lines is proposed. Impractical installation of modern measuring devices (e.g. phasor measurement unit (PMU)) throughout all network buses, due to lack of telecommunication infrastructures or funds, has imposed problems and a growing concern toward the wide-area FL problem with a limited number of measurement devices. In the most related researches, the optimal PMU placement problem for the FL and state estimation issues is separately studied. Also, the existence of occasional gross errors in the measurement set, due to cyber-attacks and various telemetry noise or failure, can bring about the wrong results for the FL algorithms. In the presented study, a PMU placement scheme is proposed for achieving both state and FL observability. Furthermore, by utilising this scheme, a new FL algorithm capable of contemplating gross measurement errors has been proposed. Faulted lines have purposely assumed unknown. In addition, by employing the voltages positive-sequence components, results have shown immunity in regards to fault type and resistance. Comprehensive numerical simulations on the IEEE 14-bus, 57-bus and 118-bus test systems have demonstrated the effectiveness of the proposed method and provided proof to this claim.

Locating Faults on Untransposed, Meshed Transmission Networks Using a Limited Number of Synchrophasor Measurements

The method of symmetrical components is not effective for fault location in the case of untransposed lines, due to potential couplings between the sequence circuits. This paper proposes a non-iterative algorithm in the phase-coordinates for wide-area fault location on untransposed transmission networks. In doing so, first, an improved two-terminal method is suggested to accurately locate faults on untransposed lines. Next, an algorithm is proposed to infer voltage and current phasors at the faulted line ends without direct measurements, by taking advantage of the data provided by phasor measurement units (PMUs). Accordingly, the adverse effect of close instrument transformers transients on the estimation accuracy is minimized. Being highly nonlinear in terms of fault distance and impedance, the fault equations are derived and made linear in this paper by defining six suitable auxiliary variables. The resulting system of equations is solved using the least-squares method to obtain three-phase voltages and currents at the faulted line ends. A main feature of the proposed algorithm is that it only requires a limited number of current and voltage synchrophasors. An additional advantage of the proposed algorithm is that the faulted line is not required to be known a-priori. The proposed algorithm is validated using extensive simulation studies on the New England 39-bus test system, accounting for different fault locations, types and resistances.

Wide-area Fault Location of Transmission Lines by Hybrid Synchronized/Unsynchronized Voltage Measurements

Global positioning system (GPS) has been deployed in phasor measurement units and protective relays to provide synchronized measurements across the grid. Synchronized measurements, however, may not be available throughout the network either due to GPS signal loss (GSL) or basically lack of required infrastructure for synchronized sampling. This paper presents a novel method for wide-area fault location incorporating both synchronized and unsynchronized voltage measurements. Complex calculus is utilized to develop a system of equations based on phase angles of synchronized measurements and magnitudes of both synchronized and unsynchronized measurements. The distributed-parameter model of the transmission lines are considered and therefore the obtained results are also valid for long transmission lines. Moreover, the proposed formulation locates the fault irrespective of fault type. Electromagnetic transient simulations for WSCC 9-bus and a 22-bus sub-network of the IEEE 118-bus test system reveal that in the face of GSL, unsynchronized measurements significantly improve fault-location estimation when the synchronized measurements are sparse.

Wide-area fault location based on optimal deployment of the traveling wave recorders

Summary With the development of wide-area measurement technology, it is possible to synchronously obtain the traveling waves from different measuring points in a complex power grid. Considering fault-generated traveling wave transmits along the shortest path in the power grid and timestamps of wave fronts can be acquired by phase-mode transformation and wavelets, this paper proposes an optimal deployment scheme of traveling wave recorders (TWR) in the power grid based on the extended double-end fault-location method. Then the fault-location methodology is presented. It is critical to guarantee that the double-end method is applied to the power grid and recognizes the specialized measuring combinations preciously and quickly, and the fault can be located consequently wherever it occurs. At last, fault-location accuracy is improved by the correction approach. All simulations are carried out in PSCAD/EMTDC, and the proposed procedure is applied to the IEEE 30& 57-bus test system to exam its validation. The results show that it can accurately locate a fault with 13 TWRs in IEEE 30-bus test system and 16 TWRs in IEEE 57-bus test system, and absolute error is less than 20 m. Copyright © 2015 John Wiley & Sons, Ltd.

A Wide-Area Scheme for Power System Fault Location Incorporating Bad Data Detection

Phasor measurements have found many applications in modern power systems. Wide-area fault location utilizing the bus-impedance matrix and available measurements is a recent achievement in the context of smart transmission grid. This paper aims at developing a wide-area fault-location scheme capable of detecting and identifying erroneous measurements. As a result, while multiple available measurements contribute to fault location in order to increase accuracy, the reliability of fault location is not compromised as the proposed scheme detects, identifies, and removes erroneous measurements. The transfer impedances between the fault location and the phasor measurements, which can be remote from the faulted line, are utilized to formulate fault location as a nonlinear fitting problem. Having estimated the fault location and total fault current, we employ statistical hypotheses testing to detect, identify, and remove bad data. In the case of unsynchronized measurements, the fitting problem is modified to include only the magnitude of measurements. The proposed method considers the distributed parameter model of the transmission lines and, therefore, the obtained results are also valid for long transmission lines. Electromagnetic transient simulations for the WSCC 9-bus and a 41-bus subnetwork of the IEEE 118-bus test system reveal successful fault location by synchronized as well as unsynchronized measurements.

A Straightforward Method for Wide-Area Fault Location on Transmission Networks

Local practices in fault location require measurements from one or more terminals of the faulted line to be available. On the other hand, the nonlinearity of circuit equations associated with wide-area fault location makes their solving process iterative and computationally demanding. This paper proposes a non-iterative method for wide-area fault location by taking advantage of the substitution theorem. Accordingly, a system of equations is constructed which can be easily solved using the linear least-squares method. The distributed-parameter line model is considered to provide a highly accurate estimation. Besides, due to inherent errors of current transformers, the current data is not taken into account to preserve the accuracy. In order to avoid uncertainties in relation with construction of zero-sequence network, just positive- and negative-sequence networks are exploited. Nonetheless, the method still is capable of pinpointing all types of short-circuit faults by using a restricted number of synchronized pre- and post-fault voltage phasors. Numerous simulation studies conducted on the WSCC 9-bus and New England 39-bus test systems verify the effectiveness and applicability of the proposed fault location method, even with limited coverage of synchronized measurements.

A Sparse-Data-Driven Approach for Fault Location in Transmission Networks

This paper proposes an efficient wide-area fault location method to find single- and double-fault locations in transmission networks. Unlike earlier conventional fault location methods, we only require capturing the phasors in a limited number of buses by phasor measurement units (PMUs). The measured voltage phasors and impedance matrix of the system yield an underdetermined system of equations that can be solved by sparse representation recovery methods. The solution gives a sparse fault current vector whose nonzero elements assign the probable faulty zones. For areas with no faults, current phasors measured by PMUs are sufficiently accurate to calculate the adjacent bus voltages. The new calculated voltages and the measured data are used to estimate the faulted lines accurately. The substitution theorem and least-squares method are used to calculate the differences between pre- and during-fault voltages, and currents in both ends of the faulted lines. Transmission line equations developed based on distributed line parameters are then used to pinpoint the fault location along each faulted line. We demonstrate the satisfactory performance of our noniterative methodology and its low computational load using simulations of the IEEE 39-bus test system with noisy measurements, multiple combinations of all fault types, and different resistances.

A Traveling-Wave-Based Methodology for Wide-Area Fault Location in Multiterminal DC Systems

While in many applications, multiterminal dc (MTDC) systems are potentially appropriate substitutes for their ac counterparts, their protection problems still require more attention. This paper proposes a novel traveling-wave-based methodology for fault location in MTDC systems. The traveling-wave principle, along with two graph theory-based lemmas, is deployed to locate the fault by sectionalizing the graph representation of the MTDC system. Accordingly, the system of equations relating the fault inception time, fault point, and first arrival time at different converter locations would be derived and solved. The method merely needs the first surge arrival times, thereby eliminating the practical problems in relation to identifying subsequent traveling waves. More important, it successfully determines the fault location, regardless of the network topology complexity, that is, the number of its meshes and radial lines. To demonstrate the effectiveness of the method, it is applied to some complicated MTDC systems containing meshes and radial lines. Numerous simulation studies carried out for different conditions verify high accuracy, robustness against fault impedance, and noise immunity of the proposed method.

Robust fault location of transmission lines by synchronised and unsynchronised wide‐area current measurements

This study presents a novel method for fault location of transmission lines by multiple fault current measurements. In contrast to conventional methods, it is proposed to utilise several current measurements, which may be far from the faulted line. The circuit equations of the network are used to express each fault current as a function of fault location. Fault location is then estimated using a least-squares estimation technique. To achieve a robust estimation of fault location, statistical hypotheses-testing is employed for identifying erroneous measurements. The method is applicable to both synchronised and unsynchronised measurements. Moreover, fault location can be estimated regardless of fault type and fault resistance. Furthermore, the method considers the distributed parameter model of transmission line and therefore the results are highly accurate. Electromagnetic transient simulations for the western systems coordinating council 9-bus and a 22-bus test system reveal accurate wide-area fault location as well as successful removal of erroneous measurements.