Online partial discharge (PD) analysis of power transformers is sometimes complex due to the presence of large disturbance and noise as well as to uncertainty in PD source identification. In this paper, a novel approach to PD detection and analysis in online power transformers is presented. The proposed approach provides hardware and software tools to remove disturbance, noise, separate contributions from different sources and, eventually, identify PD sources. Besides, a description of the hardware tools used to assemble the diagnostic system, the tests (in the lab and on real transformers) carried out to build the reference database needed for identification system training will be discussed, providing rules for PD source identification. A number of working cases will be presented to show the effectiveness of the proposed method.

The use of fossil fuels has caused an increase in GHG concentration in the atmosphere, which has a direct effect on global warming. Among the possible technologies to mitigate GHG emissions, carbon capture and storage (CCS) can be applied to existing plants and now it is being accepted officially in order to gain emission reduction certificates. This paper presents a feasible solution for CO2 capture and storage network in Italy from sources that are included in the National Allocation Plan and that are forced to reduce carbon dioxide emissions in the second phase of the implementation of the Kyoto Protocol. The technical aspects of carbon sequestration are derived from industrial applications, while transportation and storage depend on local and geological characteristics. Since Italy has complex geological characteristics, the selection of the most convenient sites should include hydrocarbon reservoirs that are currently used or are depleted. To select these sites, all oil wells that are located in the Italian territory and are managed by UNMIG (National Mining Office for Hydrocarbons and Geothermy) were considered, and a short list was selected among those that have safety and lasting characteristics to ensure a long time permanence. The position of the selected storage sites is drawn on a GIS map containing all the plants included in the National Allocation Plan to be able to identify the optimal networks for carbon dioxide transportation. The case study is located in an area that includes Milan, Pavia and Lodi districts. Knowing the amount of CO2 produced by plants in the selected zone, it is possible to determine the tons of CO2 to capture and the size of transportation and storage systems. Pipelines are, in this case, the most appropriate transport technologies. From emission and sequestration points to storage sites it is necessary to build 122km pipelines for 8MtCO2 capacity. Using this CCS grid it is possible to avoid CO2 emission with economic feasibility close to the cost of carbon trading values. In fact, the market cost of a European Union Allowance (EUA) at the start of the first period of application of Directive 2003/87/CE was about 30 h/tCO2

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In order to improve partial discharge (PD) detection and location in extruded power cables, Ultra-Wide Bandwidth detectors (UWB) can be preferred to wide-and narrowband systems. As UWB systems aim to get the broadest frequency content in PD pulses, it is important to evaluate the frequency attenuation as a function of distance propagated of the cable under test, trying to achieve optimum signal-to-noise ratio (SNR) and large detection sensitivity. Some conventional techniques able to calculate attenuation and dispersion of PD pulses are considered and a fast approximate model is developed in this paper, trying to provide a simple tool to estimate the maximum PD detection length in polymeric cable, in relation to bandwidth measurement system and required sensitivity.

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