Stimulating proactive fault detection in distributed systems

Fault Tolerance is an important issue considered when developing a reliable Distributed System. Reactive fault systems are designed to redistribute the current process on to other machines when failure occurs. In contrast to the conventional method of reactive recovery, an emerging concept in the field of fault tolerance is a proactive approach. This approach exploits pre fault symptoms and initiates fault recovery henceforth. This project is to implement a proactive fault prediction simulator for a distributed system. This will include developing a language for simulation, which allows the user to define a distributed system. The language is further used to develop an environment that integrates two fault prediction algorithms, Wilcoxon s Rank-Sum and DFT (Dispersion Frame Technique). Both these algorithms are presented as alternatives for SMART (Self Monitoring Analysis and Reporting Technology) in this project. The project also includes a comparison metrics for these prediction algorithms in terms of prediction precision and prediction accuracy

Identification of Crash Fault & Value Fault for Random Network in Dynamic Environment

During the past few years distributed systems have been the focus of considerable research in computer science. Fault tolerance in distributed systems is a wide area with a significant body of literature that is vastly diverse in methodology and terminology. Fault tolerance is the ability of a system to perform its function correctly even in the presence of internal faults. An extensive methodology has been developed in this field over the past few years, and a number of fault-tolerant machines have been developed but most dealing with random hardware faults, while a smaller number deal with software, design and operator faults to varying degrees. Our work mainly focuses on the simulation of the system that deals with software faults means the faults that occur because of the failure or error in the internal software component. Our work is restricted to distributed diagnosis in dynamic fault environment. Basically we have created different not-completely connected random networks with number of nodes ranging from 8 to 256.Then we have induced faults to these networks dynamically using poison distribution. Three different algorithms have been implemented to detect the faults and the comparison among these algorithms, based on delay latency and number of message exchanges, has been represented graphically. The software faults that we had dealt with are crash fault and value fault in a distributed system (not-completely connected network). Although many researches have been done in the crash fault area but very less work has been done in diagnosing the value faults in dynamic fault environment

Impact of increased distributed generation on fault levels and the network equipment

Attention towards the development of Distributed Generation (DG) is globally high. UK's concentration is to use sustainable and renewable sources to generate electricity thereby protecting the environment from getting polluted. In this paper, Distributed Generation concept is explored regarding the types, sizes, ratings, locations and benefits. It is very important to connect the developed distributed generator to the distribution network to satisfy the demand but without developing any faults and causing damage to the existing switchgear. Legal contracts that are required to be signed in order to connect the DG to the network and proper Protection Review to be followed in suppressing the faults are also mentioned. To study the impact of increased DG on fault levels, simulation approach is adopted. ETAP 7.1.0 is used to build a case study network and the results obtained are analyzed based on which critical comparison is made. The network comprises of three wind farms, each consisting of six wind turbines and a small hydroelectric plant. Various scenarios are considered and the results obtained are clearly analyzed. Protection is provided for the circuit and Star Device coordination study is performed. © JES 2014

Ground Fault Location of Cable Using Wavelet in DC Microgrid

As the proliferations of distributed generation and power electronic equipment in power systems, more and more researchers put focus on the DC microgrid. This study is based on cables in DC community microgrid. Single ground fault is considered in the cables connected hub garage and participating garages. With long length compared to other cables in the system, it is necessary to study the method to locate the ground fault when the fault happen in the buried cables. Two approaches are studied. The traveling wave method is applied for analysis of transient process when the fault happens while the stable parameter analysis method used for the stable process after the fault already happened. The cable model is defined using precise distributed element concept and packaged as a PLECS model. The simulation is based on the DC microgrid model in the Simulink environment with PLECS blocks. The wavelet packet decomposition is applied in the processing of signal processing procedure. The wavelet packet helps to extract the key signal and eliminate the interference in both methods respectively. The results are analyzed to show the effectiveness of location methods and wavelet packet

Non-linear circuit based model of PMSM under inter-turn fault: a simple approach based on healthy machine data

The paper proposes a fast dynamic mathematical model to evaluate the performances of saturated permanent magnet synchronous machines (PMSM) under stator winding’s inter turn fault. The parameters of the model can be determined using only manufacturer’s data of the healthy machine. Two surface mounted PMSM have been considered to investigate the validity of the proposed approach; with distributed and concentrated winding. It has been shown that the proposed model predicts the fault current with a reasonable accuracy compared to the non-linear Finite Elements analyses and to the experimental results. This model can be incorporated in a global simulation environment of power electronic of electrical device since the computation time is very short

Fault-Tolerant Load Management for Real-Time Distributed Computer Systems

This paper presents a fault-tolerant scheme applicable to any decentralized load balancing algorithms used in soft real-time distributed systems. Using the theory of distance-transitive graphs for representing topologies of these systems, the proposed strategy partitions these systems into independent symmetric regions (spheres) centered at some control points. These central points, called fault-control points, provide a two-level task redundancy and efficiently re-distribute the load of failed nodes within their spheres. Using the algebraic characteristics of these topologies, it is shown that the identification of spheres and fault-control points is, in general, is an NP-complete problem. An efficient solution for this problem is presented by making an exclusive use of a combinatorial structure known as the Hadamard matrix. Assuming a realistic failure-repair system environment, the performance of the proposed strategy has been evaluated and compared with no fault environment, through an extensive and detailed simulation. For our fault-tolerant strategy, we propose two measures of goodness, namely, the percentage of re-scheduled tasks which meet their deadlines and the overhead incurred for fault management. It is shown that using the proposed strategy, up to 80% of the tasks can still meet their deadlines. The proposed strategy is general enough to be applicable to many networks, belonging to a number of families of distance transitive graphs. Through simulation, we have analyzed the sensitivity of this strategy to various system parameters and have shown that the performance degradation due to failures does not depend on these parameter. Also, the probability of a task being lost altogether due to multiple failures has been shown to be extremely low

Design and simulation of advanced fault tolerant flight control schemes

This research effort describes the design and simulation of a distributed Neural Network (NN) based fault tolerant flight control scheme and the interface of the scheme within a simulation/visualization environment. The goal of the fault tolerant flight control scheme is to recover an aircraft from failures to its sensors or actuators. A commercially available simulation package, Aviator Visual Design Simulator (AVDS), was used for the purpose of simulation and visualization of the aircraft dynamics and the performance of the control schemes.;For the purpose of the sensor failure detection, identification and accommodation (SFDIA) task, it is assumed that the pitch, roll and yaw rate gyros onboard are without physical redundancy. The task is accomplished through the use of a Main Neural Network (MNN) and a set of three De-Centralized Neural Networks (DNNs), providing analytical redundancy for the pitch, roll and yaw gyros. The purpose of the MNN is to detect a sensor failure while the purpose of the DNNs is to identify the failed sensor and then to provide failure accommodation. The actuator failure detection, identification and accommodation (AFDIA) scheme also features the MNN, for detection of actuator failures, along with three Neural Network Controllers (NNCs) for providing the compensating control surface deflections to neutralize the failure induced pitching, rolling and yawing moments. All NNs continue to train on-line, in addition to an offline trained baseline network structure, using the Extended Back-Propagation Algorithm (EBPA), with the flight data provided by the AVDS simulation package.;The above mentioned adaptive flight control schemes have been traditionally implemented sequentially on a single computer. This research addresses the implementation of these fault tolerant flight control schemes on parallel and distributed computer architectures, using Berkeley Software Distribution (BSD) sockets and Message Passing Interface (MPI) for inter-process communication

Distributed Fault-Tolerant Algorithm for Wireless Sensor Networks

Wireless Sensor Networks (WSNs) are a set of tiny autonomous and interconnected devices. These nodes are scattered in a region of interest to collect information about the surrounding environment depending on the intended application. In many applications, the network is deployed in harsh environments such as battlefield where the nodes are susceptible to damage. In addition, nodes may fail due to energy depletion and breakdown in the onboard electronics. The failure of nodes may leave some areas uncovered and degrade the fidelity of the collected data. Therefore, establish a fault-tolerant mechanism is very crucial. Given the resource-constrained setup, this mechanism should impose the least overhead and performance impact. This paper focuses on recovery process after a fault detection phase in WSNs. We present an algorithm to recover faulty node called Distributed Fault-Tolerant Algorithm (DFTA).The performance evaluation is tested through simulation to evaluate some factors such as: Packet delivery ratio, control overhead, memory overhead and fault recovery delay. We compared our results with referenced algorithm: Fault Detection in Wireless Sensor Networks (FDWSN), and found that our DFTA performance outperforms that of FDWSN

Loosed coupled simulation of smart grid control systems

Smart grids rely on the integration of distributed energy resources towards an intelligent and distributed manner to organize the electrical power grid enabled by a bidirectional flow of information to improve reliability and robustness, fault detection and system operation, and plug-and-playability of energy devices. The integration of information and communication technologies (ICT), one of the key enablers of smart grids, will ease the deployment of intelligent and distributed systems implementing the automation functions. In this context, there is a need to assess how these systems, developed using these emergent technologies, e.g., multi-agent systems, data analytics and machine learning, will behave and affect the working conditions of the power grid. This paper aims to explore the development of a transparent and loose-coupled interface between the behavioral control system and the physical or simulated power system environment, in a coupled simulation perspective, aiming to assess and improve the development of such systems during the design phaseinfo:eu-repo/semantics/publishedVersio