Search results for "Head"

Future coastal hazard scenarios. A case study in NE Sicily (Italy)

2012

The coastal dynamics is the result of several causes that contribute to change the balance of beach deposits over time. The beach system is not always able to maintain coastal balance: the factors contributing to this phenomenon are to be found in both natural and anthropogenic spheres. In this context we present the analysis of marine geology and coastal geomorphological data of a sector between Rocca di Caprileone and Tindari (north-eastern Sicily) with the aim to: i) determine their onland-offshore area relationships, ii) analyze which natural features may contribute to coastal retreat, iii) present coastal hazard scenarios. Until fifty years ago the natural balance of this coastal area …

Evaluation of the shear connection strength of precast hybrid steel-trussed-concrete composite beams

2015

In last decades, significant efforts have been carried out by the scientific community to evaluate the main technical issues of Hybrid Steel-Trussed-Concrete beams, investigating both the first opera-tive phase, i.e. before the concrete casting, when only the bare truss works, and, the second phase, i.e. after the concrete curing, when the beam works as a composite element. In the present study, the attention is focused on the evaluation of the shear strength of the connection between the bottom plate of the steel truss and the concrete core proposing a mechanical model able to predict its ulti-mate resistance. The proposed mechanical formulation is mainly based on the extension of existing…

Maximizing energy transfer and RES integration using dynamic thermal rating. Italian TSO experience

2019

The production of electricity from wind and other renewable sources is rapidly increasing all over the world, causing significant changes in the management of electrical systems. The current structural asset is not adequate to manage this growing generation of energy. The hypothesis of construction of new power lines would mean taking into consideration economic, political and social problems. The following paper reports the experience gained by the Italian TSO, Terna S.p.A, on the use of the DTR (Dynamic Thermal Rating), which is able to dynamically calculate the real transport capacity of an overhead power line. The results obtained are en- couraging as they show how it is possible to inc…

Safety Concerns on Ground Fault Application Transfer Phenomenon in HV Installations

2007

When a fault to ground occurs in HV/MV substations supplied by a combined overhead-cable line, most of the fault current can be transferred and injected into the soil several kilometers far away from the fault location. This phenomenon is called "fault application transfer" and mostly concerns transition stations, where cables are connected to the overhead line. If the transition station is a dead-end steel pole structure, usually accessible to the general public, the local ground electrode could be inadequate to maintain ground potential rise within safety limits. Hence, dangerous touch and step voltages may appear at exposed locations. In the paper results of various computer simulations …

No-Load Energization of Very Long EHV Mixed Overhead-Cable Lines

2010

Methodologies to uprate an overhead line. Italian TSO case study

2013

The amount of wind power and other time-variable non-dispatchable electricity generation is rapidly increasing across the world, causing a significant change in the electrical system configuration. The existing structural asset isn't adequate to dispatch these new power that have a priority in the energy dispatching. In addiction the outage of substations on the grid and the increase of consumptions have caused growing load currents. In order to satisfy these needs, TSOs have adopted new measures on existing power lines and N-1 criteria to ensures the electrical grid security. These particular devices are Dynamic Thermal Rating (DTR) systems. After introducing thermal resistant conductors a…

Dynamic thermal rating for overhead lines: Self-adaptive protection device

2013

The increase in the consumption of electricity, the stringent environmental restrictions and the need to keep costs, make ever more meaningful the need for a flexible operation of existing overhead lines. This paper studies the possibility to use a dynamic thermal rating for overhead line starting from the analysis of the mathematical model and the ability of the latter to reflect the temperature of an overhead conductor in different ambient condition; then it simulates the thermal behaviour of a conductor both in steady state and dynamic one. Finally the paper shows a method for a self-adaptive thermal protection system.

Transient behaviour of a “mixed” overhead-cable EHV line under lightning events

2009

Recently, in many countries have been undergone or are planning links with AC extra-high voltage (EHV) underground cables. Cable lines offer the possibility of a reduced environment impact and for this reason they are often the only alternative for the reinforcement or the expansion of power system accepted by public opinion. The coexistence of overhead and cable line in the so called ¿mixed¿ lines, however, raises several questions regarding their behaviour both in steady state and in transient. The purpose of this work is to investigate the transient behaviour of a mixed overhead-cable EHV line under lightning events, describing the effects of the following overvoltages on the system. The…

Transient stability assessment of SMIB System with Mixed overhead-cable line – Sensitivity analysis

2009

Uprating an overhead line. Italian TSO applications to increase system N-1 security

2013

This paper analyzes innovative devices to optimize the energy flows transmission on existing overhead lines. Indeed sometimes the structural asset isn’t adequate to manage energy generated by Renewable Energy Source (RES) in particular operating conditions. In addiction the outage of primary substations on the grid and the increase of consumptions have caused growing load currents. In order to satisfy these needs, TSOs have adopted new measures on existing power lines and N-1 criteria to ensures the electrical grid security. These particular devices are Dynamic Rating systems. After introducing thermal resistant conductors and Dynamic Rating (DR) solutions, paper reports two different appli…