Search results for " Fault"

Ground Fault Current Distribution in Substations Supplied by Nonuniform Multi-Section Lines

2007

he paper presents a general method for computing the distribution of substation ground fault current. The feeding line can be entirely homogeneous along its whole length or consisting of two or more different sections, i.e. part overhead and part underground cable. Based on the two-port theory, the proposed method allows to take into account all the relevant conductively and inductively coupled parameters which take part to the distribution of the fault current and can be easily implemented in a computer program. Numerical examples demonstrate the high efficiency of the proposed method.

Practical tables for the design of the grounding systems in distribution networks in presence of metallic interconnection

2009

The present paper deals with the dependence of the ground current, due to a single-line-to-ground fault in a secondary substation, on the electrical and geometrical parameters of a Medium Voltage distribution network in which a metallic interconnection between the grounding systems is realized. Examining different situations, some easy-to-use tables are provided for a practical approach to the design of the ground electrodes of the secondary substations in these networks. The relevance of the work is due to the lack in the international standards of specific indications on how to consider the presence of the interconnection elements in distribution networks.

Approccio allo Sviluppo di Sistemi Diagnostici per il Funzionamento Fault Tolerant delle Micro-grid

2009

Il progressivo aumento del livello di penetrazione della generazione distribuita(GD) è destinato a provocare un profondo mutamento nelle esistenti reti di distribuzione che non sono più considerate come terminazioni passive del sistema elettrico complessivo. Una soluzione possibile è quella relativa alla realizzazione di piccole reti, le micro-grid, che riproducono, al loro interno, la struttura del sistema di produzione e distribuzione dell’energia elettrica. Per ottenere una adeguata affidabilità della micro-grid risulta importante la individuazione e la gestione dei guasti ai fini del perseguimento dell’esercizio "fault tolerant" della micro-grid stessa. Nel presente lavoro, dopo aver in…

A New Protection Strategy for Electrical Distribution Systems

2010

In this paper, the authors propose a new protection strategy for electrical Medium Voltage distribution networks, based on a distributed intelligence system composed of a central unit and of many local processing units. The distributed intelligence system can precisely identify and locate faults in suitably limited times. Each local processing unit is composed of a data acquisition system and a data analysis system. The first allows the accurate reconstruction of the fundamental using only 1.5 cycles of under fault transient electrical quantities. The second performs suitably precise on-line fault diagnosis based on the data provided by the data acquisition module. The data acquisition algo…

DESIGN OF A FAULT AND PARTIAL DISCHARGES LOCATION DEVICE FOR CABLE POWER NETWORK

In this thesis, a digital device for fault and on line partial discharge location is presented. The device employs the traveling wave method for two or multiple ends. The designed prototype shows interesting features connected to the low cost and to the possibility to collect data from different locations thus providing additional functionalities deriving from pre-fault and data analysis, relating the existence of defects to the subsequent fault event. The device also enables the acquisition of the temperature on the cable section where the sensor is installed. Such installation can also support DSO and TSO for carrying out both on-event and condition based maintenance, discovering the caus…

METABOLIC NETWORKS ROBUSTNESS: THEORY, SIMULATIONS AND RESULTS

2011

Metabolic networks are composed of several functional modules, reproducing metabolic pathways and describing the entire cellular metabolism of an organism. In the last decade, an enormous interest has grown for the study of tolerance to errors and attacks in metabolic networks. Studies on their robustness have suggested that metabolic networks are tolerant to errors, but very vulnerable to targeted attacks against highly connected nodes. However, many findings on metabolic networks suggest that the above classification is too simple and imprecise, since hub node attacks can be by-passed if alternative metabolic paths can be exploited. On the contrary, non-hub nodes attacks can affect cell …

Modeling and Verification of Symbolic Distributed Applications Through an Intelligent Monitoring Agent

2022

Wireless Sensor Networks (WSNs) represent a key component in emerging distributed computing paradigms such as IoT, Ambient Intelligence, and Smart Cities. In these contexts, the difficulty of testing, verifying, and monitoring applications in their intended scenarios ranges from challenging to impractical. Current simulators can only be used to investigate correctness at source code level and with limited accuracy. This paper proposes a system and a methodology to model and verify symbolic distributed applications running on WSNs. The approach allows to complement the distributed application code at a high level of abstraction in order to test and reprogram it, directly, on deployed network…

ARC FAULT DETECTION EQUIPMENT AND METHOD USING LOW FREQUENCY HARMONIC CURRENT ANALYSIS

2012

An arc fault detection circuit includes a current sensing circuit coupled to a line conductor carrying a current. The current sensing circuit operates to sense current and output data indicative of the sensed current. A processing circuit implements a frequency transform algorithm to transform the output data to frequency data in a low frequency range and with a high spectral resolution where a minimum short time observation window is concerned. The processing circuit identifies an arc fault condition on the line conductor by identifying differences in said frequency data between at least two subsequent observation windows and identifying characteristics which exceed thresholds.

Granular packings and fault zones

2000

The failure of a two-dimensional packing of elastic grains is analyzed using a numerical model. The packing fails through formation of shear bands or faults. During failure there is a separation of the system into two grain-packing states. In a shear band, local ``rotating bearings'' are spontaneously formed. The bearing state is favored in a shear band because it has a low stiffness against shearing. The ``seismic activity'' distribution in the packing has the same characteristics as that of the earthquake distribution in tectonic faults. The directions of the principal stresses in a bearing are reminiscent of those found at the San Andreas Fault.

The extensional Messaria shear zone and associated brittle detachment faults, Aegean Sea, Greece

2005

Structural, thermochronological and metamorphic data are used to elucidate the tectonic nature and evolution of the ductile extensional Messaria shear zone and the associated brittle Messaria and Fanari detachment faults, which exhumed their footwall from mid-crustal depths on the island of Ikaria in the Aegean. Thermobarometric data indicate that the Messaria shear zone formed at 350–>400 °C and 3–4 kbar (i.e. at a depth of c . 15 km). Normal faulting was accompanied by the intrusion of two granites, which together with the thermobarometric data indicate a relatively high thermal field gradient of 25–35 °C km −1 . Zircon and apatite fission-track and apatite (U–Th)/He ages demonstrate rapi…