Fault locating for traveling-wave accelerators based on transmission line theory

Radio-frequency(RF)breakdown analysis and location are critical for successful development of high-gradient traveling-wave(TW)accelerators,especially those expected to generate high-intensity,high-power beams.Compared with commonly used schemes involving dedicated devices or complicated techniques,a convenient approach for breakdown locating based on transmission line(TL)theory offers advantages in the typical constant-gradient TW-accelerating structure.To deliver such an approach,an equivalent TL model has been constructed to equate the TW-accelerating structure based on the fun-damental theory of the TL transient response in the time domain.An equivalence relationship between the TW-accelerating structure and the TL model has been established via analytical derivations associated with grid charts and verified by TL circuit simulations.Furthermore,to validate the proposed fault-locating method in practical applications,an elaborate analysis via such a method has been conducted for the recoverable RF-breakdown phenomena observed at an existing prototype of a TW-accelerating-structure-based beam injector constructed at the Huazhong University of Science and Technology.In addition,further considerations and discussion for extending the applications of the proposed method have been given.This breakdown-locating approach involving the transient response in the framework of TL theory can be a conceivable supple-ment to existing methods,facilitating solution to construction problems at an affordable cost.

Fault Analysis and Structure Optimization of Traveling Transmission System of Shuttle Car

This paper firstly introduces the common faults of traveling transmission system of shuttle car.Secondly,by analyzing the characteristics of shuttle car structure,the layout of traveling transmission system and the common faults on shuttle car,this paper concludes that"internal holding torque"is the main cause of faults.Finally,this paper proposes a corresponding optimization design scheme to reduce the impact of"internal torque",and calculates the relevant results through the finite element simulation analysis method.Through these analyses and calculations,it is shown that the method can effectively reduce the probability of failure of traveling transmission system of shuttle car.

Transmission line fault-cause identification method for large-scale new energy grid connection scenarios

The accurate fault-cause identification for overhead transmission lines supports the operation and maintenance personnel in formulating targeted maintenance strategies and shortening the time of inspecting faulty lines.With the goal of achieving“carbon peak and carbon neutrality”,the schemes for clean energy generation have rapidly developed.Moreover,new energy-consuming equipment has been widely connected to the power grid,and the operating characteristics of the power system have significantly changed.Consequently,these have impacted traditional fault identification methods.Based on the time-frequency characteristics of the fault waveform,new energy-related parameters,and deep learning model,this study proposes a fault identification method suitable for scenarios where a high proportion of new energy is connected to the power grid.Ten parameters related to the causes of transmission line fault and new energy connection scenarios are selected as model characteristic parameters.Further,a fault identification model based on adaptive deep belief networks was constructed,and its effect was verified by field data.

Fault diagnosis of power-shift steering transmission based on multiple outputs least squares support vector regression

A method of multiple outputs least squares support vector regression （LS-SVR） was developed and described in detail, with the radial basis function （RBF） as the kernel function. The method was applied to predict the future state of the power-shift steering transmission （PSST）. A prediction model of PSST was gotten with multiple outputs LS-SVR. The model performance was greatly influenced by the penalty parameter γ and kernel parameter σ2 which were optimized using cross validation method. The training and prediction of the model were done with spectrometric oil analysis data. The predictive and actual values were compared and a fault in the second PSST was found. The research proved that this method had good accuracy in PSST fault prediction, and any possible problem in PSST could be found through a comparative analysis.

Operation of offshore wind farms connected with DRU-HVDC transmission systems with special consideration of faults

The diode rectifier unit(DRU)-based high-voltage DC(DRU-HVDC) system is a promising solution for offshore wind energy transmission thanks to its compact design, high efficiency, and strong reliability. Herein we investigate the feasibility of the DRU-HVDC system considering onshore and offshore AC grid faults, DC cable faults, and internal DRU faults. To ensure safe operation during the faults, the wind turbine(WT) converters are designed to operate in either current-limiting or voltage-limiting mode to limit potential excessive overcurrent or overvoltage. Strategies for providing fault currents using WT converters during offshore AC faults to enable offshore overcurrent and differential fault protection are investigated. The DRU-HVDC system is robust against various faults, and it can automatically restore power transmission after fault isolation. Simulation results confirm the system performance under various fault conditions.

Monitoring Contact State of Laboratory Fault with Coda Transmission Waves

We monitored the amplitude changes of coda transmission waves around 500 kHz across the frictional interface of a simulated 1. 5-meter-long fault during normal stress holding test.We find that the amplitude of coda transmission waves increases with the logarithm of stationary contact time. Localized increase amounted to a level ranging from 4% to 16%along the fault is observed during the 1-hour experiment. We discuss that the frictional strength at mesoscopic scale,which is related to the amplitude of coda transmission waves,is responsible for the phenomenon. Combining the reported method with other complementary approaches will enhance the understanding of fault mechanism either at laboratory or on-site applications.

Analysis on the fault characteristics of three-phase short-circuit for half-wavelength AC transmission lines

Half-wavelength AC transmission(HWACT) is an ultra-long distance AC transmission technology, whose electrical distance is close to half-wavelength at the system power frequency. It is very important for the construction and operation of HWACT to analyze its fault features and corresponding protection technology. In this paper, the steady-state voltage and current characteristics of the bus bar and fault point and the steady-state overvoltage distribution along the line will be analyzed when a three-phase symmetrical short-circuit fault occurs on an HWACT line. On this basis, the threephase fault characteristics for longer transmission lines are also studied.

Accurate Fault Location Modeling for Parallel Transmission Lines Considering Mutual Effect

:A new accurate algorithms based on mathematical modeling of two parallel transmissions lines system(TPTLS)as influenced by the mutual effect to determine the fault location is discussed in this work.The distance relay measures the impedance to the fault location which is the positive-sequence.The principle of summation the positive-,negative-,and zero-sequence voltages which equal zero is used to determine the fault location on the TPTLS.Also,the impedance of the transmission line to the fault location is determined.These algorithms are applied to single-line-to-ground(SLG)and double-line-to-ground(DLG)faults.To detect the fault location along the transmission line,its impedance as seen by the distance relay is determined to indicate if the fault is within the relay’s reach area.TPTLS under study are fed from one-and both-ends.A schematic diagrams are obtained for the impedance relays to determine the fault location with high accuracy.

Gear Transmission Fault Classification using Deep Neural Networks and Classifier Level Sensor Fusion

Gear transmissions are widely used in industrial drive systems.Fault diagnosis of gear transmissions is important for maintaining the system performance,reducing the maintenance cost,and providing a safe working environment.This paper presents a novel fault diagnosis approach for gear transmissions based on convolutional neural networks(CNNs)and decision-level sensor fusion.In the proposed approach,a CNN is first utilized to classify the faults of a gear transmission based on the acquired signals from each of the sensors.Raw sensory data is sent directly into the CNN models without manual feature extraction.Then,classifier level sensor fusion is carried out to achieve improved classification accuracy by fusing the classification results from the CNN models.Experimental study is conducted,which shows the superior performance of the developed method in the classification of different gear transmission conditions in an automated industrial machine.The presented approach also achieves end-to-end learning that ean be applied to the fault elassification of a gear transmission under various operating eonditions and with signals from different types of sensors.

Correlation Analysis Algorithm for Transmission Line Fault Location Based on Travelling Wave

This paper introduced correlation method to locate transmission line fault.First it described the principle of transmission line fault location based on traveling waves.The principle of correlation analysis is introduced,then the method using correlation analysis in fault location is given.Transmission line model is established with EMTP-ATP.Basing on the model,some kinds of fault are simulated.The feasibility of this algorithm is proved based on simulation results.By comparing with the classical wavelet analysis,this paper gave the advantages of this algorithm in two cases:noise influence suppression and accuracy of near distance fault location.Experiment is established to simulate transmission line grounding fault.The experiment result showed the correlation algorithm's validity.All the analysis result indicated that the correlation algorithm have a high precision.

Modern Travelling Wave Based Fault Location Techniques for HVDC Transmission Lines

The modern travelling wave based fault location principles for transmission lines are analyzed.In order to apply the travelling wave principles to HVDC transmission lines,the special technical problems are studied.Based on this,a fault locating system for HVDC transmission lines is developed.The system can support modern double ended and single ended travelling wave princi- ples simultaneously,and it is composed of three different parts:travelling wave data acquisition and processing system,communication network and PC based master station.In the system,the fault generated transients are induced from the ground leads of the over-voltage suppression capacitors of an HVDC line through specially developed travelling wave couplers.The system was applied to 500 kV Gezhouba-Nanqiao(Shanghai)HVDC transmission line in China.Some field operation experiences are summarized,showing that the system has very high reliability and accuracy,and the maximum location error is about 3 km(not more than 0.3%of the total line length). Obviously,the application of the system is successful,and the fault location problem has finally been solved completely since the line operation.

Fault Location Method for STATCOM Connected Transmission Lines Using CCM

Determining the fault location using conventional impedance based distance relay in the presence of FACTS controllers is a challenging task in a transmission line. A new distance protection method is developed to locate the fault in a transmission line compensated with STATCOM with simple calculations. The proposed protection method considers the STATCOM injected/absorbed current to correct the fault loop apparent impedance and accordingly calculates the actual distance to the fault location. The comprehensive equations needed for apparent impedance calculation are also outlined and the performance is evaluated and tested with a typical 400 KV transmission system for different fault types and locations using MATLAB/SIMULINK software. The evaluation results indicate that the new protection method effectively estimates the exact fault location by mitigating the impact of STATCOM on distance relay performance with error less than 0.3%.

Guaranteed Cost Active Fault-tolerant Control of Networked Control System with Packet Dropout and Transmission Delay

The problem of guaranteed cost active fault-tolerant controller （AFTC） design for networked control systems （NCSs） with both packet dropout and transmission delay is studied in this paper. Considering the packet dropout and transmission delay, a piecewise constant controller is adopted. With a guaranteed cost function, optimal controllers whose number is equal to the number of actuators are designed, and the design process is formulated as a convex optimal problem that can be solved by existing software. The control strategy is proposed as follows： when actuator failures appear, the fault detection and isolation unit sends out the information to the controller choosing strategy, and then the optimal stabilizing controller with the smallest guaranteed cost value is chosen. Two illustrative examples are given to demonstrate the effectiveness of the proposed approach. By comparing with the existing methods, it can be seen that our method has a better performance.

Classification of Transmission Line Ground Short Circuit Fault Based on Convolutional Neural Network

Ground short circuit faults in current transmission lines are common in the power systems.In order to prevent the power system from aggravating the accident caused by short-circuit faults of transmission lines,a novel convolutional neural network(CNN)model is constructed to identify the short-circuit fault of the transmission line in the power system.The CNN model is mainly consisted of five convolutional layers,three max-pooling layers,one concatenate layer,one dropout layer,one fully connected layer,and a Softmax classifier.This method uses a fixed time window to intercept system short-circuit fault data,extracts the deep features of these data from the training samples,and then corresponds the extracted features to labels one-to-one.Finally,in PSCAD/EMTDC,the new England 10 machine 39 nodes are taken as an example to realize the simulation.The experimental results show that the CNN model can quickly and accurately identify the short-circuit fault types,and the optimal model accuracy rate reaches 99.95%.The results of this manuscript-have positive effect on enhancing the disaster prevention capability and the operation stability of transmission lines.

Online One-End Fault Location Algorithm for Parallel Transmission Lines

Fault location and distance protection are essential smart grid technologies ensuring reliability of the power system. This paper describes an accurate algorithm for locating faults on double-circuit transmission lines. The proposed approach is capable of identifying the faulted circuit of a parallel transmission line by checking the estimated fault location and fault resistance. Voltage and current measurements from only one of the terminals of the faulty line are used. No pre-fault data are required for the estimation. The lumped parameter line model considering shunt capacitance is utilized for the derivation of the algorithm. It’s assumed that line parameters are known and transmission lines are fully transposed. The method is applicable to all types of faults. It’s evinced by evaluation studies that the proposed algorithm can correctly determine the faulted circuit in most cases. For exceptional cases, the current waveforms during the fault can be used to help identify the faulted circuit. The proposed algorithm generates quite accurate fault location estimates, and may be suitable for distance relaying.

T-Shaped Transmission Line Fault Location Based on Phase-Angle Jump Checking

In order to effectively solve the dead-zone and low-precision of T-shaped transmission line fault location,a new T-shaped transmission line fault location algorithm based on phase-angle jump checking is proposed in this paper.Firstly,the 3-terminal synchronous fundamental positive sequence voltage and current phasors are extracted and substituted into the fault branch distance function to realize the selection of fault branch when the fault occurs;Secondly,use the condition of the fundamental positive sequence voltage phasor at the fault point is equal to calculate all roots(including real root and virtual roots);Finally,the phase-angle jump check function is used for checking calculation,and then the only real root can be determined as the actual fault distance,thereby achieving the purpose of high-precision fault location.MATLAB simulation results show that the proposed new algorithm is feasible and effective with high fault location accuracy and good versatility.

Fault location of two-parallel transmission line for double phase-to-earth fault using one-terminal data

An accurate algorithm for fault location of double phase-to-earth fault on transmission line of direct ground neutral system is presented. The algorithm, which employs the faulted phase network and zero-sequence network as fault-location model in which the source impedance at the remote end is not involved, ef-fectively eliminates the effect of load flow and fault resistance on the accuracy of fault location. The algorithm achieves accurate location by measuring only one local end data and is used in a procedure that provides automatic determination of faulted types and phases, and does not require the engineer to specify them. Simulation results showed the effectiveness of the algorithm under the condition of double phase-to-earth fault.

Evaluating transmission towers potentials during ground faults

During ground faults on transmission lines,a number of towers near the fault are likely to acquire high potentials to ground.These tower voltages,if excessive,may present a hazard to humans and animals.This paper presents analytical methods in order to determine the transmission towers potentials during ground faults,for long and short lines.The author developed a global systematic approach to calculate these voltages,which are dependent of a number of factors.Some of the most important factors are:magnitudes of fault currents,fault location with respect to the line terminals,conductor arrangement on the tower and the location of the faulted phase,the ground resistance of the faulted tower,soil resistivity,number,material and size of ground wires.The effects of these factors on the faulted tower voltages have been also examined for different types of power lines.

Single Ended Fault Location Estimation for EHV Transmission Systems

A novel numerical algorithm for fault location estimation of single-phase-to-earth fault on EHV transmission lines is presented in this paper. The method is based on one-terminal voltage and current data and is used in a procedure that provides the automatic determination of faulted types and phases, rather than requires engineer to specify them. The loop and nodal equations comparing the faulted phase to non-faulted phases of multi-parallel lines are introduced in the fault location estimation models, in which source impedance of remote end is not involved. Precise algorithms of locating fault are derived. The effect of load flow and fault resistance,on the location accuracy, are effectively eliminated. The algorithms are demonstrated by digital computer simulations.

Effects of Un-transposed UHV Transmission Line on Fault Analysis of Power Systems

The conventional fault analysis method based on symmetrical components supposes that the three-phase parameters of un-transposed transmission line are symmetrical in case of fault. The errors caused by the method with the symmetrical distributed parameter circuit model as the equivalent circuit of the un-transposed ultra high voltage(UHV) transmission line were studied under both normal operation and fault,and the corresponding problems arising were pointed out. By contrast with electromagnetic transient and power electronics(EMTPE) simulation results with the asymmetrical distributed parameter circuit model of un-transposed line, it is shown that the conventional method cannot show the existence of negative and zero sequences before fault happening and there are many errors on voltage and current after fault happening which are different with fault types. The error ranges of voltage and current are 2.13%-81.13% and -7.82%- -86.15%, respectively.