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Report RSE 15000374

Study of methodologies and tools for the management and development of lineeelettriche in AC and DC

Report

2014.

Request Document (20.30 MB, .pdf)

J. Borghetto (RSE SpA), M. Garotta (RSE SpA), S. Chiarello (RSE SpA), P. Omodeo Gianolo (RSE SpA), E. Golinelli (RSE SpA), U. Perini (RSE SpA) , R. Malgesini (RSE SpA) , L. Barbieri (RSE SpA), G. Pirovano (RSE SpA) , A. Villa (RSE SpA)

T&D 2014 - Transmission and distribution of the electric energy

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The activity, reported in the Deliverable, is aimed at the study and implementation of tools and products for the management of AC and DC electrical lines, of models of degradation phenomena of components ad of the relevant laboratory and field measurement techniques and methodologies (by monitoring systems), of new testing methodologies for the characterization of innovative line and substation components.

In particular with reference to issues relevant to the insulation of lines and substations the following activities were carried out:

• Assembling, wiring and final implementation of the new system for the measurement of insulator contamination for DC lines.
• The development of accelerated aging tests (and the related test facility) of insulators made of polymeric material in the presence of DC voltages.
• The development of test protocols for polymeric insulators removed from service, in order to quantify the degree of dielectric strength under conditions of high severity of environmental pollution.
• The development and installation of field monitoring systems of the behavior of line and substation insulators, for the evaluation of the performance over time of solutions aimed to increase the withstand of line and station insulators.

For matters related to the increase of the transport capacity of the lines, a survey of the conductors on the market and the ones being introduced in the same, was carried out, also with reference to the activities carried out in the years within RdS. Also in this regard, an analysis was made of pre-normative research in progress (CIGRE) and the standards under definition (IEC, CENELEC, ASTM).

Again with reference to issues related to the increase in transport capacity, the work done in this PAR has led to the creation of a complete prototype of the optical system of measurement of ground clearance (Saglas Safe), through the integration of components developed for the realization of the prototype and functional testing of the complete prototype.

With reference to the problems connected to the measurement of the electric field profiles along composite insulators, the activity of the development of a prototype array of fiber optic sensors has led, in the course of this PAR, to the realization of a complete prototype. The prototype allows the measurement of the electric field simultaneously in 10 points aligned on a length of 70 cm. Based on the project identified in the course of the previous RdS period, the drawings of the prototype were made, the new fiber sensors realized on dielectric support and a dedicated software in Labview environment produced. From the measurements carried out it was possible to highlight that the trends measured by each sensor are not perfectly superimposable for a same position along the insulator. A possible explanation (confirmed by simulations software) to the phenomenon is given by the variation of the dielectric constant between air and the dielectric material constituting the support, which can affect locally the direction of the electric field. To mitigate the effect due to the presence of the rod in the glass fiber it is possible to resort to the use of materials with low dielectric constant for the support of the sensors and for their protection.

With regard to the problems of air discharge phenomena, the work done in this PAR has examined the numerical and experimental methodologies that enable the comparison of the current pulse measured by an electrode in the face of a corona injection in air and its simulation of the phenomenon. Preliminary comparisons between simulations and measurements were performed.

Real scale application of the code has also been carried out; in particular, the code has been used to estimate the leakage current of a length of a high voltage line current.

The research work developed during this implementation plan has allowed us to verify how the structure of the code developed is robust and reliable, but the parameters included in the model should be finetuned in order to obtain more realistic forecasts.

The first simulations in this field have highlighted such as chemical modeling is of primary importance in this field and the absorption of the electrons emitted by the corona effect by neutral particles plays a crucial aspect. The adoption of a refined chemical model is being tested and the first estimates show how the length of distance for the absorption of electrons varies from several meters to a few centimeters.

With reference to the development of the robotic device (ILENA), during the current PAR steps were taken to implement the latest hardware and software changes to the prototype. The changes enabled the robotic device to autonomously overcome a suspension clamp and a compression mid-span joint installed on a span at the laboratory of experimental mechanical tests RSE Brugherio.

The activity demonstrated the feasibility of the implementation of a robotic device of small dimensions able to move independently along a phase conductor of a high voltage power line, passing the fittings that equip the line itself.

In the course of this PAR it was also accomplished the last stage of cooperation envisaged in the RSEACEA on the line and off line diagnostic of cable network of medium voltage (MV). In particular downstream of the activities, which have enabled us to develop and develop measurement techniques and algorithms for the evaluation of the degradation of cables and related components of the line (terminals and joints), at the RSE laboratories, more checks were carried out through the use of mobile laboratories of RSE and ACEA. The checks have allowed to compare the measurement techniques used and to introduce further refinements of the algorithms of evaluation of the state of the components.

Downstream of this phase, we proceeded to the field testing of these measurement techniques through the use of mobile laboratory ACEA and with the collaboration of RSE.

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