This paper deals with the possibility of installing gas-insulated transmission lines (GILs) in dedicated or shared structures. The applications involve railway galleries (both in the proper galleries and in service or pilot tunnels), highway networks, and gas lines. The high GIL power capability together with very low power losses configures these applications as high transmission efficiency corridors. Some issues of this application will be shown in this paper (steady-state regime of the line, voltage drops, power losses, voltage unbalance factor, ampacity, electromagnetic field impact, and limit lengths). Moreover, this paper discusses the necessary studies to be carried out and the problems that have to be faced in order to develop this kind of application toward a feasible technical solution

In this paper, a single-ended travelling wave-based fault location algorithm is presented with reference to HV (i.e. 60 kV) overhead unearthed operated lines. The main novelty of this contribution lies in the method of calculating the speed of the earth mode component of the travelling wave, which exploits the wave impedance and wave capacitance, and of simplifying the fault location procedure. The developed procedure has been applied to a real double-circuit overhead line modelled by EMTP-rv, whereas the fault location algorithm has been implemented in Matlab environment. In order to validate the proposed method, a sensitivity analysis has been performed by varying the fault position, the fault resistance and the fault inception angle. The proposed approach has proven to be independent of all these parameters.

This paper deals with an integral numerical method suitable to predict the current density distribution in typical multiconductor systems represented by gas-insulated lines (GIL) or by isolated phase MV bus ducts, highlighting their proximity effect. Besides the prediction of power density distribution due to Joule losses, the integral approach makes the evaluation of the external flux density easy. The simplicity of the approach, the conciseness of the matrix algebra applied, and the close-to-reality procedure make this method extremely attractive for self-made software implementation on any commercially available math packages such as Matlab. For the sake of comparison, a finite-element method (FEM) model of the system has been implemented. In this model, a coupling between electric circuit and electromagnetic model has been used in order to take into account the real power supply conditions.

This paper deals with the analysis of carrier signal transmission in medium-voltage (MV) distribution networks. A multiconductor matrix procedure based on the bus admittance matrix, which accounts for the earth return currents, enables predicting the high-frequency behavior of the distribution networks and, hence, the effectiveness of transmitted signals. To this aim, suitable models have been implemented based on the Carson's theory for overhead lines with ground return and Wedepohl's theory for cable lines. A comparison with the modal analysis demonstrates the advantages of the multiconductor matrix algorithm with respect to the modal analysis. In order to validate the theoretical results, two measurement campaigns have been carried out on real MV networks. A good agreement between measured and computed values has been verified. Since distribution networks are generally unlike each other, the procedure becomes a valuable tool, which makes it easy to assess the feasibility of distribution line carrier (DLC) applications in any system. In particular, a protection system to prevent the islanding of dispersed generators is proposed. In addition, in a foreseeable hypothesis of allowed islanding operation of portions of distribution networks (microgrids), DLCs are proposed as communication control of the interface device at the point of common coupling