Fault Simulation Research Articles

Simulation Research on the Post-arc Dielectric Recovery Characteristics of Multi-break Vacuum Circuit Breakers

The dielectric recovery characteristics are very important for the successful interruption of the vacuum circuit breaker. In order to explore the influence of the post-arc dielectric recovery characteristics of the multi-break vacuum circuit breaker on its breaking, this article establishes a simulation model of the multi-break vacuum circuit breaker and a 750kV short line fault simulation circuit in MATLAB. By adjusting the dielectric recovery characteristics of different breaks, the critical dielectric recovery rate (The minimum dielectric recovery rate of the break when the circuit breaker does not break down) under different conditions is finally obtained. In addition, the influence of the equalizing capacitor on the critical recovery rate is also explored. It is found that the smaller the grading capacitance, the greater the voltage of the break, and the greater the critical dielectric recovery rate.

Deep learning based optimum fault diagnosis of electrical and mechanical faults in induction motor

Among all the motors Induction motor (IM) plays a vital role in industry and the demand for their reliability and safe operation is increasing day by day. They are reliable but they do wear out if not maintained timely which in turn will lead to excessive loss of revenue and also man power and this motivates us to develop an intelligent methodology for diagnostic of incipient faults in Induction Motor. This paper focuses on the development of optimum Deep Learning based diagnostic technique to detect the mechanical and electrical faults in Induction Motor. Here, mechanical and electrical faults of different severity level are being tested on machine fault simulator using acquired current and vibrational signals. In this work, optimum model of Deep Neural Network (DNN) based on critical vibration and current features is developed and finally used to timely and effectively detect that which kind of faults the given IM is dealing with. The results are added and discussed in the result and discussions.

Level Crossing Barrier Machine Faults and Anomaly Detection with the Use of Motor Current Waveform Analysis

Barrier machines are a key component of automatic level crossing systems ensuring safety on railroad crossings. Their failure results not only in delayed railway transportation, but also puts human life at risk. To prevent faults in this critical safety element of automatic level crossing systems, it is recommended that fault and anomaly detection algorithms be implemented. Both algorithms are important in terms of safety (information on whether a barrier boom has been lifted/lowered as required) and predictive maintenance (information about the condition of the mechanical components). Here, the authors propose fault models for barrier machine fault and anomaly detection procedures based on current waveform observation. Several algorithms were applied and then assessed such as self-organising maps (SOM), autoencoder artificial neural network, local outlier factor (LOF) and isolation forest. The advantage of the proposed solution is there is no change of hardware, which is already homologated, and the use of the existing sensors (in a current measurement module). The methods under evaluation demonstrated acceptable rates of detection accuracy of the simulated faults, thereby enabling a practical application at the test stage.

Fault-Tolerant Control Strategy with Asymmetric Phase Currents for Single to Four-Phase Open-Circuit Faults of Six-Phase PMSM

Multi-phase motors and generators are regarded with great fault tolerance capability, especially on open-circuit faults. Various mathematics analytical methods are applied for their fault control. In this paper, a fault-tolerant control strategy with asymmetric phase current for the open-circuit faults with arbitrary phases in the six-phase PMSM (six-phase permanent magnetic synchronous motor, 6P-PMSM) system, is proposed for better electrical and dynamical performance of the machine. An innovative mathematical model for PMSM under one to four-phase-open circuit faults are established considering the asymmetry of the machine. Combining with time-varying relations in machines’ working conditions, targeted decoupling transformation matrixes of every kind of open-circuit faults are settled by voltage equations under different faults. Modified control strategy with a connection between the neutral point and the inverter’s DC side is presented, which aims at increasing the system redundancy and reducing the amplitude of phase currents. Besides, improved control loops with two layers are put forward as well, with which the PMSM system acquires fewer harmonics in phase current and smoother electromagnetic torque. Simulation and experimental results of open-circuit faults are provided for verification of the theoretical analysis.

A pilot line protection for MT-HVDC grids using similarity of traveling waveforms

Protection of dc line faults is a major challenge for the operation of multi-terminal high-voltage dc (MT-HVDC) grids. To avoid blocking converter and system shutdown, ultra-fast protection is required to detect and isolate line fault with the application of hybrid dc circuit breaker. This paper proposes a pilot protection scheme based on improved Hausdorff distance to detect the overhead line fault for MT-HVDC grid. Compared with literature, this protection method owns higher withstanding ability of noise interference, start-up delay and data anomaly. Moreover, the fault segment can be correctly identified as independent of fault location, and protection sensitivity is maintained even under internal ground fault with high impedance of up to 1000 Ω. The issue of dead zone fault recognition is considered and solved in this paper with reasonable sacrifice in the sampling frequency requirement. Based on Zhangbei HVDC grid in China, a four-terminal dc grid model is developed in PSCAD/EMTDC environment for fault simulation, and the data processing is performed in MATLAB platform. The feasibility and effectiveness of this protection scheme are verified by a simulation study that considers different scenarios.

Coseismic fault lubrication by viscous deformation

Despite the hazard posed by earthquakes, we still lack fundamental understanding of the processes that control fault lubrication behind a propagating rupture front and enhance ground acceleration. Laboratory experiments show that fault materials dramatically weaken when sheared at seismic velocities (>0.1 m s−1). Several mechanisms, triggered by shear heating, have been proposed to explain the coseismic weakening of faults, but none of these mechanisms can account for experimental and seismological evidence of weakening. Here we show that, in laboratory experiments, weakening correlates with local temperatures attained during seismic slip in simulated faults for diverse rock-forming minerals. The fault strength evolves according to a simple, material-dependent Arrhenius-type law. Microstructures support this observation by showing the development of a principal slip zone with textures typical of sub-solidus viscous flow. We show evidence that viscous deformation (at either sub- or super-solidus temperatures) is an important, widespread and quantifiable coseismic lubrication process. The operation of these highly effective fault lubrication processes means that more energy is then available for rupture propagation and the radiation of hazardous seismic waves. Viscous deformation is a potentially prevalent mechanism of fault lubrication during earthquakes, according to laboratory experiments that simulate seismic faulting of various rock-forming minerals.

Transfer learning based methodology for migration and application of fault detection and diagnosis between building chillers for improving energy efficiency

Faulty operation of HVAC chillers may result in increased energy usage, reduced thermal comfort, and increased maintenance costs. Establishing reliable fault detection and diagnosis (FDD) methods can effectively avoid these adverse effects. Most existing FDD studies only focus on training specific fault diagnostic models for particular chillers. Very few works have been found to address the issue of how to transfer FDD between different chillers, which is a promising but challenging task. This paper presents a generic framework for transferring the prior knowledge of an information-rich source chiller to build the diagnostic model for a new target chiller. Heterogeneous data standardization is firstly presented to standardize the original datasets of different chillers. Domain adaption transfer learning is then applied to overcome the domain shift introduced by the differences of feature distribution across chillers, and domain adversarial neural network is used to generate the diagnostic model for the target chiller where only easy-to-collect normal operation data of the target chiller and the prior knowledge are used for training. To verify the presented transfer learning, two screw chillers are used as the source and target chillers accordingly, and large quantities of fault simulation experiments are performed on them. Results indicate that the transferred diagnostic model for the target chiller yields decent diagnostic performance, the accuracy for the first and second cycles are 81.27% and 74.93%, respectively. In comparison with five conventional machine learning models with accuracy less than 55%, the proposed transfer learning approach has significant performance advantages and practical application potential.

Permanent Fault Location for Three-Core Cable Using Multiconductor Coupling Model

Phase-to-ground faults in underground cables are usually correlated with the metallic sheaths. This work proposes a fault location method for the three-core cable in distribution system using voltage and current measurements at the both terminals. First, a generic model for the three-core cable with independent sheath is constructed by lumped parameter approach. Then, considering the practical measurement restrictions, a simplified yet effective equivalent circuit is proposed on the basis of the generic model. Additionally, the analysis of the earthed strap current is presented. The earthed strap current is used to determine cable fault distance by voltage and current equations. By PSCAD/EMTDC, an effectiveness evaluation of the proposed model is given, and the performance of the proposed algorithm is investigated with extensive fault simulations. The results demonstrate the method is not affected by different fault conditions. Finally, the comparison with other algorithms shows higher accuracy and feasibility of the proposed method for a three-core cable with independent sheath.

On the Effect of Grain Fragmentation on Frictional Instabilities in Faults With Granular Gouge

AbstractThe evolution of frictional strength during stick‐slip dynamics of a fault system is key to understanding earthquake nucleation and rupture patterns. In mature faults, granular gouge is produced by wear, comminution or fragmentation during tectonic movements. In this work, we introduce a fragmentation model in the simulation of a sheared granular fault to explore the influence of grain breakage on the stick‐slip dynamics. With fragmentation of highly stressed particles, the fault frictional strength increases accompanied by many small slip events triggered by particle breakage. The small fragments produced by particle breakage are not only stronger and more difficult to break, but they also change the distribution of contact forces, leading to the strengthening of the fault system. Based on statistical analyses on the size distribution of slip events with different particle strengths, we find that with lower particle strength, slip events become more correlated with particle fragmentation events and that the number of large slip events decreases. In addition, our analyses on the relationship between slip and particle fragmentation events reveal three types of correlations: In the first and second types, particle fragmentation events trigger micro or major slips, respectively. In the third category, large‐scale particle fragmentations take place at the end of large slip events owing to stress localization during post‐slip particle rearrangements. Our results in this work highlight the role of micromechanics of particle fragmentation in the failure of fault damage zones and help in understanding the relation between particle breakage and frictional failures.

Fault Detection Analysis for Three Phase Induction Motor Drive System using Neural Network

One of the most important components of the industrial process is known to be the three-phase induction motor. This device, however, is prone to electrical and mechanical faults, which may cause a substantial component or financial losses. The fault analysis received growing attention due to a need to increase reliability and to decrease potential output loss due to machine breakdown. Thus, the purpose of this paper is to present a simple and reliable fault analysis based on the Neural Network (NN) is proposed. The NN method is a simpler approach without a diagnostic professional to review data and diagnose issues. Various fault disputes of induction motor are developed and analysed using the NN method. The main types of faults considered are over-voltage, under-voltage, and unbalanced voltage faults. The trained network is tested with simulated fault current and voltage data.

Busbar Differential Protection Using an Alternative Generalized Alpha Plane

This paper describes an alternative busbar differential protection function based on the generalized alpha plane. This approach faithfully maps several currents in two equivalent currents such that it preserves the original restraint and operation signals. The original formulation was applied to multi-terminal transmission lines protection but the number of terminals can be small if compared with the number of bays connected to busbars. For this reason, this first method is initially assessed in order to verify its suitability for busbar protection purposes. After that, an alternative algorithm to map the currents in the same plane is described and tested by using a double-bus-single-breaker 220 kV busbar configuration, modeled in ATPdraw. The simulations of internal and severe external faults, as well as evolving faults, are performed for a wide variety of scenarios including fault times, fault resistances and fault types. The results bring up a greater robustness and shorter response time if compared with original alpha plane approach, thus it represents an alternative as a busbar protection function which provides high reliability and it can be easily implemented in a commercial relay due to its mathematical simplicity.

Cross-Country faults in resonant-grounded networks: Mathematical modelling, simulations and field recordings

Cross-Country Faults (CCFs) are defined by the occurrence of two Single Phase-to-Ground faults taking place simultaneously in different phases and at different locations of the galvanically connected network. Few studies about these faults in MV systems have been done so far, particularly with real fault data and simulations. In this work, first a mathematical model is derived to understand basic properties of CCFs. Then, simulations in RSCAD/RTDS® using real data obtained from an utility in Scandinavia are discussed and validated with two real faults measured in the field for resonant-grounded networks in Sweden and Norway. The mathematical calculations proved to have a good accuracy and showed important properties of CCFs such as the dependency of both faults of each others fault resistance and location. Furthermore, it was observed that such faults can be very different from more common types of faults in the power system. Interesting behaviors can appear particularly when feeders are connected in ring, where an extra current with smaller magnitude and 180∘ appears on the measurement point, as well as in lines with double infeed where a very large difference is detected depending on the fault location which influences directly both ends of the line.

Identification of temporal anomalies of spectrograms of vibration measurements of a turbine generator rotor using a recurrent neural network autoencoder

A method is proposed for recognizing pre-emergency conditions of rotary installations based on the use of the Hamming window and advanced Deep Learning techniques in retrospective analysis of the results of accounting for the factors of operation of a turbine generator, diagnostics and control under critical impacts. A program of experimental studies on the model of a turbine plant with simulation of faults and receiving vibration signals has been developed. An experiment based on the homostatic method of checking the signal with Hamming windows, in the frequency, time and modulation domains and common initial data, allows one to determine the most promising signal characteristics for identification. A method has been developed for monitoring the state of turbine generators in an automatic mode for timely notification of the CHPP personnel about the appearance of signs of pre-emergency situations, as well as about the nature of faults by the method of predicting the state of a pre-emergency situation using convolutional neural networks implemented in the form of a recurrent autoencoder. Clustering is applied and clusters are identified that correspond to the spectrograms of pre-emergency situations. The effectiveness of the use of the homostatic method in combination with correlation analysis is based on the decision-making model described in more detail in other works.

Improved Hausdorff Distance Based Pilot Protection for Multi-terminal HVDC system

In order to overcome the weakness of dc line protection under high impedance fault, a traveling wave similarity based pilot protection method is proposed using improved Hausdorff Distance algorithm. The issue of asynchronous data, noise and anomalies are solved with the improved Hausdorff Distance algorithm. The instantaneous frequency based wave head detection method is used to overcome the problem of delay in protection start-up. Based on this protection scheme, external fault can be distinguished from internal faults regardless of fault impedance, fault location and fault type. Moreover, the faulty pole and fault direction are recognized via ratio of transient energy at line terminals. Taking the Zhangbei high voltage dc transmission project as an example, a four-terminal ring type dc grid model is developed in PSCAD/EMTDC platform for fault simulation and the data processing is performed in MATLAB platform. Based on the theoretical analysis and simulation study, the proposed pilot protection is verified with excellent fault impedance withstanding ability and robustness against noise, abnormal data and asynchronous data.

Frictional properties of basalt experimental faults and implications for volcano-tectonic settings and geo-energy sites

We performed a suite of experiments aimed at examining the frictional properties of unaltered basalts at conditions considered to be representative of slip at shallow depths in volcano-tectonic environments and in-situ geo-energy basaltic sites. Scientific drilling and field studies on exhumed subsurface faults and fractures analogues suggest that, frictional sliding in basalts can occur in shear zones within a volume of wear debris or along localized joint surfaces. To illuminate how microstructural heterogeneities affect the nucleation of slip instabilities in basalts, we sheared simulated fault gouge and bare rock surfaces at low normal stresses (4–30 MPa) at ambient temperature, under room-dry and wet conditions. We performed velocity steps (0.1–300 μm/s) and slide-hold-slides (30–3000 s holds) to determine the frictional stability and healing properties of basalts. In all the tests, we observed high friction coefficient associated with important frictional restrengthening. Overall, our results show that microstructural heterogeneities strongly affect the friction velocity dependence of basalts: while for normal stresses ≥10 MPa, shear localization accompanied by cataclasis and grain size reduction favors the transition to velocity weakening behavior of powdered samples, on bare surfaces gouge production during shearing promotes a transition to a velocity strengthening behavior. Our results imply that at the tested conditions, friction instabilities may promptly nucleate in shear zones where deformation within (unaltered) basaltic gouge layers is localized, such as those located along volcanic flanks, while joint surfaces characterized by rough rock-on-rock contacts are less prone to unstable slip, which is suppressed at velocities ≥10 μm/s.

Fault Diagnosis via Neural Ordinary Differential Equations

Implementation of model-based fault diagnosis systems can be a difficult task due to the complex dynamics of most systems, an appealing alternative to avoiding modeling is to use machine learning-based techniques for which the implementation is more affordable nowadays. However, the latter approach often requires extensive data processing. In this paper, a hybrid approach using recent developments in neural ordinary differential equations is proposed. This approach enables us to combine a natural deep learning technique with an estimated model of the system, making the training simpler and more efficient. For evaluation of this methodology, a nonlinear benchmark system is used by simulation of faults in actuators, sensors, and process. Simulation results show that the proposed methodology requires less processing for the training in comparison with conventional machine learning approaches since the data-set is directly taken from the measurements and inputs. Furthermore, since the model used in the essay is only a structural approximation of the plant; no advanced modeling is required. This approach can also alleviate some pitfalls of training data-series, such as complicated data augmentation methodologies and the necessity for big amounts of data.

Adaptive traveling wave-Based algorithm for time alignment of transmission line fault records

In this paper, an adaptive traveling wave (TW)-based algorithm for time alignment of transmission line fault records is presented. The solution analyzes only the arrival times of incident and fault-reflected TWs at both line terminals, adapting itself to the line travel time. As a result, it overcomes the need for line travel time settings, as required by earlier TW-based time synchronization approaches, leading the proposed method to be more robust to line parameters uncertainties. To evaluate the proposed algorithm, simulated and real fault records are assessed, considering different time alignment error levels. The results demonstrate that the proposed approach is reliable and able to synchronize local and remote line fault records with accuracy of few microseconds.

Practical assessment of POTT and DCB teleprotection schemes using computer environment

Several tools are used for evaluating teleprotection schemes in transmission lines, however, there is no concern about the cost-benefit ratio of the use of these methodologies. In this paper, six tools applied in these methodologies commonly used for teleprotection evaluation are compared, seeking to achieve the best possible cost-benefit ratio. The most cost-effective tool is used to solve a complex testing problem with realistic relay models from different manufacturers, in order to evaluate the POTT and DCB teleprotection schemes. To do so, CAPE fault simulations were carried out in a 230 kV/60 Hz power system. From the obtained results, the DCB scheme has proved to be more efficient than the POTT for the evaluated scenarios with the use of CAPE software, which in turn presented itself as a reliable alternative to high-cost loop hardware methodologies for the evaluation of teleprotection schemes.

RESEARCH STATUS OF CIVIL ENGINEERING STRUCTURES ACROSS FAULTS AND THE DEVELOPMENT OF EXPERIMENTAL DEVICES FOR FAULT SIMULATION

How to ensure the safety of structures and facilities across seismic faults and to mitigate losses due to fault dislocation are of a great significance in the development of resilient engineering systems. With the transfer of the construction of major and mega-projects to the deep ground, the deep sea and the central and western regions, the safety problem of civil engineering across faults has become increasingly prominent. This paper reviews the characteristics of faults and structural damage states related to the large earthquakes within recent years, and points out the necessity and urgency of carrying out destructive tests on crossing-fault structures and facilities, as well developing associated simulation programs. In addition, this study summarizes the state-of-the-art research progress on typical damaging mechanism of crossing-fault structures and facilities and discusses the limitations of simulating cross-fault damages by using currently available shaking tables. The objective of the study is to provide a reference and a guidance for the development of fault simulation device, and for the related researches on equipment manufacture, and for experimental design and planning.

Research on Fault Vibration Signal Features of GIS Disconnector Based on EEMD and Kurtosis Criterion

Gas insulated metal enclosed switchgear (GIS) has been widely used in the world because of its compact structure and adaption to the environment. However, due to frequent operation and other reasons, GIS disconnector is prone to mechanical failure with poor contact, leading to abnormal vibration signals. In this paper, a GIS disconnector contact fault simulation platform is built to collect vibration signals in three states: normal contact, moderate poor contact and severe poor contact of disconnector contact. The Ensemble Empirical Mode Decomposition (EEMD) method is used to decompose the vibration signals, and the IMF decomposition signals are screened by Kurtosis criterion (a numerical statistic method). Finally, the vibration signal features of GIS under different conditions are obtained by reconstructing the screening signals. The results indicate that, under the normal contact, the frequency of GIS vibration signal mainly presents the distribution of 100 Hz and its integer multiple frequency component, when there is a contact defect, the high frequency component in the vibration signal spectrum increases significantly, and the tripling frequency component is present, and the amplitude of component will increase with the severity of the fault. Therefore, this study provides a theoretical reference for on‐line monitoring of GIS disconnecting switch contact fault. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.