Ricerc@Sapienza

We investigate the improvement of the lightning performance of overhead power lines through the use of additional ground wires placed below the phase conductors. The analysis of the electrical system is carried out through a method based on the conventional multiconductor transmission-line formalism. In the presence of a direct lightning, both the currents flowing in phase conductors and ground wires and the overvoltages across insulator strings can easily be evaluated. The main effects of such additional ground wires are here pointed out through an accurate numerical analysis.

The improvement of the lightning performance of overhead distribution lines, hit by direct strokes, is investigated considering the use of additional shield wires beneath the phase conductors. The frequency-domain theory of multiconductor transmission lines with periodical grounding is adopted permitting a rigorous evaluation of the phase and shield wire currents and of the overvoltages across insulators. These can be minimized by careful positioning of the underbuilt shield wires.

The proper monitoring and operation and maintenance (O&M) of solar photovoltaic (PV) systems are an integral part of the service tasks required to ensure long-term reliability and prolonged lifetime of the installation. In the recent years, with the end of the feed-in-tariff legislation, the PV stakeholders and operators shifted their focus from the design and construction of utility-scale grid-connected PV plants to the development of monitoring and more efficient O&M practices.

In high voltage transmission lines, the shield wires are often sectionalized for several reasons. This practice may have considerable effects on power line communications in multiconductor transmission lines. A careful simulation is performed in order to put in evidence the relevant channel features.

Real-time monitoring of the operation state of wide-area transmission line links has become possible with the help of phasor meter units. Synchronized information acquired by phasor meter units needs to be adequately processed to permit the accurate estimation of the line constants of the transmission link. In this paper, a novel general rigorous compact procedure for correctly processing the measured voltage and current phasors of uniform multiconductor transmission line systems is proposed.

We study the shielding performance of shield wires in overhead power lines. We propose a novel chain matrix formulation, that employs longitudinally symmetric transmission-line cells to more efficiently, and correctly, simulate the propagation behaviour over the line accounting for the periodical grounding. The analysis is performed in the frequency domain and results in time domain are obtained through inverse Fourier transform. In the case of direct lightning, we can easily compute overvoltages across insulator strings for insulation coordination purposes.