Single-ended Fault Location Method Research Articles

A Single-Ended Fault Location Method for Transmission Line Based on Full Waveform Features Extractions of Traveling Waves

Conventional single-ended traveling wave fault location methods, which commonly depend on partial features of traveling wavefronts, may lead to fault location failure, especially for weak-signal faults such as high impedance or zero-crossing faults and close-in faults. To tackle it, this paper presents a fault location method according to the extracted panoramic features of traveling wave full waveform (TWFW) in time-frequency domains. Firstly, two rules of the TWFW features are probed, that is, the wavefront arrival sequence is varied from fault sections, as well as the frequency distribution of wavefronts is strongly related to the precise fault distance. Ergo, the mapping relationships between the TWFW and fault distance are qualitatively confirmed in order to demonstrate the uniqueness of the TWFW subsequently. Next, a LeNet-5-based convolution neural network (CNN) model is constructed to quantitatively evaluate such mapping relationships. In this model, various TWFW features will be extracted to the convolution channels when the CNN parameters are optimized adaptively, and the mapping relations can be formed in light of these sensitive features to estimate the fault distance. Finally, a Grad-CAM visualization method is deployed in the case study, and the accuracy along with the robustness of the proposed method in various fault conditions can be validated consequently.

A novel noniterative single-ended fault location method with distributed parameter model for AC transmission lines

Fast and accurate fault location methods can save costs and ensure power supply reliability. This paper proposes a novel noniterative single-ended phasor domain fault location method with distributed parameter model for AC transmission lines. Due to the limitation of information, the legacy impedance-based single-ended fault location methods usually are based on assumptions on the line or system to obtain more information. The method proposed in this paper takes advantage of the additional information brought by the operation mode of circuit breakers. The proposed method only needs the local measurements and does not need the measurements and the equivalent source parameters of the remote system. The proposed method only uses single-ended data and is not affected by communication and synchronization. The proposed method is noniterative and there is no risk of non-convergence. In addition, the method proposed in this paper does not rely on the assumptions of legacy methods and considers the distributed parameters, avoiding the disadvantages of the legacy methods. The effectiveness of the proposed method is verified through a lot of case studies in PSCAD/EMTDC, with different fault types, fault locations and resistances.© 2017 Elsevier Inc. All rights reserved.

A Single-Ended Fault Location Method for Grid-Connected Converter System Based on Control and Protection Coordination

Traditional single-ended fault location method is influenced by the fault resistance, and the remote in feed, which reflects as the two equations built by fault phase have four unknowns. And in the grid-connected converter system, the weak feedback characteristic further reduces the performance of the method. To solve it, a single-ended fault location method based on control and protection coordination is proposed in this paper. First, using the high controlled-ability of the converter, the control strategy for fault ride-through (FRT) operation is divided into two stages by switching control modes. Then, according to the electrical quantities under two stages, four uncorrelated equations can be established, and the equations still have four unknown parameters. The fault distance can be calculated by solving them. The simulation results show that the proposed method has high accuracy and is immune to fault resistance and fault location, it solves the problem of insufficient equations in principle.

Research on a New Single-End Fault Location Method for Single-Phase Grounding Faults of Transmission Lines Through Transition Resistance

A single-end fault location method for single-phase nonmetallic grounding faults of transmission lines in a double terminal system is studied and proposed. First, the reason for the poor accuracy of the single-end fault location method in case of single-phase nonmetallic grounding faults is analyzed theoretically, and the necessary conditions for the single-end accurate fault location are put forward. Second, under the necessary conditions of the single-end accurate fault location, according to the topology of fault component networks, the calculation method of the single-end accurate fault location of transmission lines in a double terminal system is studied. Moreover, the influence of line capacitance is considered in this fault location method, and a simple expression for calculating the fault distance is obtained. Finally, the transmission line with a single-phase nonmetallic grounding fault is modeled in PSCAD; therefore, the correctness and the ability against transition resistance of the new single-end fault location method are verified by simulation.

A fast-executing single ended fault location method using transmission line characteristics for wind parks integrated HVDC network

Protection programs against DC faults in the HVDC Networks play a critical role in the development and expansion of integrated HVDC networks. When DC fault happens in HVDC network, every passing second counts huge power loss which makes a fast executing fault detection system necessary. Traditional fault detection methods either lacks accuracy or consume significant time in execution. This paper proposes fast-executing single ended method computing fault location within a few microseconds just after arrival of the first wave front of fault surge at the terminal of the HVDC network. The proposed method utilizes frequency dependent transmission line characteristics and travelling wave wavefront information for determining location of fault. The proposed method's functionality is tested in PSCAD simulation with realistic models. The results have been further compared with existing fault location methods and the proposed method shows suitable accuracy and significantly faster execution.

Single-ended line fault location method for multi-terminal HVDC system based on optimized variational mode decomposition

In order to provide a backup plan for double-ended fault location scheme when data communication and synchronization are not effective or available, a single-ended fault location method is proposed using traveling wave (TW) theory. The time-frequency characteristics is utilized to extract fault feature for fault location estimation. Specifically, Variational Mode Decomposition (VMD) is adopted and further improved with singular entropy based parameter optimization and TW arrivals can be clearly identified via intrinsic mode function (IMF) result. In order to solve the issue of highly attenuated TW front, Teager Energy Operator (TEO) is used to visualize the singular points in IMF and the peaks in TEO spectrum indicate the fault TW arrivals. Moreover, frequency-dependent TW propagation velocity is determined by center frequency of selected IMF to enhance accuracy. The fault simulation is performed on the platform PSCAD/EMTDC based on example model of 15-bus CIGRE HVDC system and MATLAB is used for signal processing and algorithm development. The effectiveness and superiority of this method is verified with simulation study considering potential influence.

Single-ended active injection for fault location in hybrid MMC-HVDC systems

The traditional fault location methods on DC lines are facing many challenges such as low reliability and unsatisfied location accuracy. To ensure a more reliable fault recovery of DC line, a single-ended fault location method based on active detection is proposed for hybrid modular multilevel converter based high voltage DC transmission systems. The high controllability of hybrid MMC is utilized to activate the control strategy of injecting a sinusoidal signal. Furthermore, based on parameter identification and compensation methods for the distributed parameter model, the fault location equation with fault impedance parameters is formulated. Finally, the fault location can be identified under different fault scenarios. Simulation results verify the effectiveness and accuracy of the proposed active detection method. The proposed method can pinpoint the fault location with a lower sampling rate, its accuracy is not influenced by increasing of the line length and variation of the fault impedance.

A novel single-ended fault location method for long-distance HVDC transmission lines based on cross-correlation analysis

The transmission line, as the faultiest device in power system, cross many complex areas which will cause worse work condition. This is, both the rate of faulty and the difficulty of the manual fault location are raised. While accurate fault location method could reduce the workload and outage cost, increase the speed of repairing and improve both the reliability and economics of power system. Therefore, it is essential for HVDC systems which have much longer transmission lines. The existing fault location device of HVDC transmission lines are based on the principle of transient travelling-wave. However, due to the interference caused by on-off of power electronic devices and signal resonances, the single-ended travelling-wave method can not be applied in HVDC. The characteristics of clutter interferences of HVDC system and the coupling between double pole lines are analyzed in paper. A novel single-ended travelling-wave fault location method for HVDC transmission lines based on the correlation between two pole lines is proposed. The signal of the non-fault pole line is applied as reference signal; the method suppresses interference through the cross-correlation calculation between the fault and the no-fault pole line. So the reflected wave is enhanced and the identification reliability of the reflected wave is improved. The validity of the method is verified by simulation and on-site data analysis.

A single-ended fault location method for DC lines in bipolar MMC-HVDC system

Fault location of DC grid is one of the crucial techniques for safe and reliable operation of power systems. This paper presents a single-ended fault location method for DC lines in bipolar high-voltage direct current transmission based on modular multi-level converter (MMC-HVDC) system, which focuses on short-distance DC lines. Firstly, the fault path after tripping is considered to be equivalent to a two-order RLC series circuit, and the initial voltage of the fault path is provided by the residual voltage of MMC submodule capacitors. Then, the differential equation of the fault path is established in time domain. Finally, by sampling the voltage and current signal of single-end MMC submodule capacitor and the voltage signal of the MMC bridge arm inductor, the fault distance, as well as the fault resistance, is obtained. A bipolar MMC-HVDC model is built by PSCAD/EMTDC, and the proposed method is verified by MATLAB. The simulation results show that the proposed method can accurately locate the fault position and is almost immune to the fault resistance.

Time‐domain single‐ended fault location method that does not need remote‐end system information

This study presents a single-ended fault location method that does not need the information of the remote-end system. As the foundation of the proposed method, the fault location equations under different fault types are derived based on the fault loops. The fault distance, fault impedance, and equivalent resistance and inductance of the remote-end system are considered as the unknowns of the fault location equation. Then the equation can be solved using the Gauss-Newton method, by which the four unknowns can be obtained. Therefore, the proposed method is not sensitive to the fault impedance and the system parameters. A two-terminal 500 kV ac transmission line test system is built in PSCAD to verify the proposed method. Numerous simulation data of faults of different fault distances, fault impedances, and fault types verify the accuracy and robustness of the proposed method. The proposed method is a time-domain method that can locate the fault using 5 ms data after the faults.

A New Single Ended Fault Location Method for Transmission Line Based on Positive Sequence Superimposed Network during Auto Reclosing

This paper presents a new single ended fault location method for transmission line based on positive sequence superimposed network during auto-reclosing. The proposed method only requires local measurement data and can not only eliminate but also quantify the negative effects of fault resistance, fault distance, and unknown remote end source impedance, which are marked as the most challenging problems in single ended fault location algorithms. In this paper, by analyzing the operation of auto-reclosing, the transmission line model using positive sequence superimposed network during both fault time section and reclosing time section has been developed to establish the system equations regarding fault position and local measurement data of each discrete time section. In order to retrieve converged and accurate fault location from resulting nonlinear equations, the trust-region reflective algorithm is applied in this paper. Various case studies and evaluations based on EMTP/ATP and RTDS simulations have been carried out to illustrate the effectiveness of the proposed method. The proposed new fault location method is also potentially economical as it can be relatively straightforward to implement in the standard protection hardware platform.

Six-sequence Component Based Single Ended Fault Location Method of Transmission Line

Six-sequence component based single ended fault location method of transmission line went forward on the basis of line distributed parameter model. The same and reverse direction component can be obtained through the decoupling of the same tower, Based on the reverse current and voltage boundary conditions of different faults, the fault location algorithm of double circuit lines can be obtained. (Single line three phase fault and the cross line fault with the same name are excluded) The principle of the algorithm is not affected by transition resistance, system impedance and distributed capacitance. Besides, the algorithm only uses the current, hence it won’t be affected by the transmission characteristics of the voltage transformer. The precision of ranging is not affected by the characteristics of the current transformer is also theoretically proved. There is no pseudo root for the ranging equation and it has unique solution. The simulation results show that the proposed algorithm has high accuracy and can meet the ranging requirements of high voltage and ultrahigh voltage transmission lines.

海底电缆–架空线B型混合线路行波故障测距新方法

分析了海底电缆–架空线混合线路发生故障以后行波的传播特性，并提出了一种针对海底电缆–架空线B型混合输电线路的行波测距方法。首先把原有的B型三段混合输电线路分解组合成两段A型混合输电线路，先利用每段A型混合线路两端监测装置监测到的故障初始行波浪涌到达监测点的时间差与整定时间进行比较，对故障区段初步判断，依据监测点接收行波的时间再根据单端原理得出准确的测距结果。此方法不但可以消除单端测距方法故障区段判别中对第二个波头性质的识别的难题，并且可消除双端测距方法计算故障距离时两端间不能精确同步和线路长度对测距结果的影响。PSCAD仿真实验表明，本文所提出的关于海底电缆–架空线混合输电线路故障行波测距方法是可靠的，且测距精度得到了有效提高。 After analyzing the propagation characteristics of the traveling wave after the failure of the sub-marine cable-overhead line hybrid line, a fault location method through traveling wave for the hybrid transmission line is proposed. First, the original B type hybrid transmission line is decom-posed into two hybrid transmission lines of type A. Then the time difference between the two monitoring device located in the endpoints of each A type hybrid line is used to make a preliminary judgment of the fault section. Finally an accurate fault location result is made according to the principle of single-end method. This method eliminates the difficult problem of the identification of the second wave heads in the single-end fault location method, and it also eliminates the influence of the out-sync of time and the influence of the line length which is given of the two double-end fault location method. PSCAD simulation experiments show that the presented the Fault Location Method through Traveling Wave for the Submarine Cable-Overhead Line Hybrid Line is reliable, and the accuracy of fault location has been effectively improved.

A traveling wave natural frequency-based single-ended fault location method with unknown equivalent system impedance

SUMMARY Single-ended traveling-wave fault location methods have difficulties in identifying the incident traveling wave and its corresponding reflection from the fault point. Thus, the algorithms' accuracy is always affected by wave-front identification. In this paper, a novel single-ended fault location method based on traveling wave natural frequencies is proposed for transmission line. The key of this method is to extract natural frequency and to achieve system parameters, of which system equivalent impedance is difficult to obtain accurately in practical application. By means of analyzing the influence mechanism of system impedance in the existing location algorithms based on natural frequencies, and assuming that the system resistance and inductance are parameters to be identified, a nonlinear objective function is constructed by several natural frequencies, then its local optima is solved by Nelder–Mead search algorithm to get the computing impedance. The correct system reflection angle under corresponding frequency can be attained by this computing impedance and accurate fault location can be finally estimated. The reliability and adaptability of the proposed method are verified by PSCAD/EMTDC-based simulation. Fault location result is independent of fault distance, fault type and transition resistance; meanwhile, during the computing process the accuracy of fault location can be evaluated. Copyright © 2015 John Wiley & Sons, Ltd.

A fault-location method for VSC-HVDC transmission lines based on natural frequency of current

This paper presents a novel method for locating fault on VSC-HVDC transmission line using one terminal current data. The proposed method is developed based on the natural frequency of distributed parameter line model. In the presence of the large shunt capacitor at both terminals of the VSC-HVDC line, the high frequency traveling wave is approximately totally reflected at the terminals. It is found that the value of natural frequency of VSC-HVDC transmission line is only related to fault distance and wave speed. Using this characteristic, a single-end fault location method is developed. The natural frequency can be obtained by the PRONY algorithm. Compared with traveling wave method, this approach can use any section of the in-fault data to locate fault, without having to capture the instant at which wave-front arrives, which requires higher sampling rate. A short data window is sufficient for extracting natural frequency accurately in practice. The proposed method is verified using the frequency-dependent line model in EMTDC. The simulations have demonstrated validity, rapidity and accuracy of the proposed fault location algorithm.

A single-ended fault location method for segmented HVDC transmission line

This paper presents a single-ended traveling wave-based fault location method for segmented high voltage DC (HVDC) transmission lines; an overhead line combined with an underground cable. DC transient voltage and current signals at the sending-end of the overhead line are assumed to be available. Discrete Wavelet Transformation (DWT) is then applied to the DC voltage and current signals. The wavelet energies of voltage and current transients over 16ms (i.e. 1-cyle in 60-Hz frequency) are calculated and then normalized. The normalized energies are used as the input to a binary Support Vector Machine (SVM) classifier for faulty section identification (underground cable or overhead line). Once the faulty section is identified, the faulty-half is determined by comparing polarity of the first two current traveling waves. Bewley diagrams are finally observed for the traveling wave pattern and the wavelet coefficients squared of DC voltage are used to locate the fault. The transient voltage and current for different fault locations are simulated using the ATP software. MATLAB is used to process the simulated transients and apply the proposed method. The performance of the proposed method is evaluated for different fault locations and fault resistances. The impacts of non-linear high impedance faults (NLHIF) and cable aging are also studied.

A new single ended fault location algorithm for combined transmission line considering fault clearing transients without using line parameters

In this paper a new single ended fault location method is proposed for underground cable combined with overhead lines. In this algorithm fault clearing high frequency transients are used instead of fault-generated transients and the line parameters are not needed. In the proposed algorithm, samples just from voltage transients generated by fault clearing action of circuit breaker are taken from the sending end of the cable line. Applying wavelet transform, the first three inceptions of traveling waves to the fault locator are detected. Using these, the proposed algorithm at first identifies fault section, overhead or cable, and then wave speed is calculated and at last location of fault is determined accurately. Because of using only voltage samples taken from one terminal, it is simple and economic and does not need to GPS and data communication and synchronization. Extensive simulations carried out using SimPowerSystem toolbox of MATLAB, confirm the capabilities and high accuracy of the proposed method under different system and fault conditions.

Travelling wave time–frequency characteristic-based fault location method for transmission lines

Single-ended travelling wave fault location methods have the advantages of avoiding the complexities and costs of the remote-end synchronisation. However, the determination of the arrival time of the travelling wave and its corresponding propagation velocity is a difficult problem which is apt to limit the algorithms’ accuracy. A novel single-ended fault location method based on travelling wave time–frequency characteristics for transmission lines is proposed in this study. The time–frequency characteristics of the travelling wave signal are described by the Lipschitz exponent. The Lipschitz exponent of the second transient wave-front signal is estimated by using the wavelet transform and the least square method. Afterwards the frequency component of the travelling wave, which is best for fault location, and its corresponding arrival time and propagation velocity can be determined. Then the proposed method calculates the fault distance precisely based on the determined time and velocity. Extensive simulations have been carried out in PSCAD/EMTDC, and the results demonstrate that the accuracy of the proposed fault location method is significantly improved comparing with that of the traditional travelling wave fault location method. The proposed method is insensitive to different fault conditions, and it adapts to both transposed and untransposed lines well.

A New Single-Ended Fault Location Method Based on Bergeron Model

On EHV transmission lines, the impact of distributed capacitance is necessary to be considered in case of fault location. A novel fault location method for single-phase grounded fault of transmission lines is presented based on the distributed parameter model of transmission line. In this method only the voltage and current of single end is used. The residual phase voltage at the fault point should have the same phase angle as the current through fault branch due to the pure resistive characteristics of the fault path impedance. By virtue of searching the minimum phase angle differ-ence between the phase voltage along the transmission line and the fault-component current meas-ured at the side equipped with protection, the fault distance can be located. ATP simulations are used to generate data that are supplied as inputs to the fault location algorithm.