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The effect of nanoclay on various material properties like damping and strength of typical thermoset polymers, such as epoxy and vinyl ester, was investigated. Different environmental conditions typical for high-voltage transmission pylons made of composite materials were taken into account. Resin samples were prepared with various clay weight fractions ranging from 0% to 3%. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and rheological analysis were used to study the morphology and the structure of the nanocomposites. For all nanoclay-modified thermoset polymers, the morphology was found to be of exfoliated structure mainly. Static, uniaxial tensile tests showed that the addition of nanoclay to thermoset polymers led to a beneficial effect on the stiffness, whereas the tensile strength and ductility significantly decreased. When exposed to different environmental conditions, nanoclay was found to have a positive influence on the dynamic properties, analysed by a dynamic mechanical thermal analysis. The addition of nanoclay to the thermoset resin led to an increase of the damping properties by up to 28% for vinyl ester and up to 6% for epoxy at 220°C. The dielectric properties were evaluated by electrical breakdown strength tests resulting in 11% better insulating behaviour for nanoclay-modified vinyl ester.

In recent years, the global energy environment has become increasingly severe, and the problems such as global warming, soaring carbon emissions, and excessive use of petrochemical energy have attracted increasing attention from all walks of life. The construction industry, which accounts for about 30% of the total energy consumption, needs to effectively manage and use renewable energy. The application of building information model (BIM) in the evaluation of retrofitting schemes of existing buildings is one of the main research issues in the field of building digital twins at present. The method of this research is to use 3D laser scanning technology to efficiently create the building energy model (BEM) of existing buildings and to identify and evaluate the feasibility of existing building retrofitting schemes. The purpose of this research is to evaluate the retrofitting scheme of existing buildings based on the concept of nearly zero-energy buildings (nZEBs), aiming to improve the energy efficiency of existing buildings and use clean energy to satisfy building energy demand. According to the case study in this paper, an nZEBs solution suitable for the building can reduce building energy costs by 14.1%, increase solar photovoltaic power generation by 24.13%, and reduce carbon dioxide emissions by 4306.0 kg CO2eq/a.

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A design of a fully composite pylon has been proposed for new-generation 400 kV transmission towers to save line corridors and to reduce visual impact. Correspondingly, a method of external down-leads is proposed to bring grounding potential to the shield wires, together with a plan that not all pylons are grounded called 'partially grounded transmission lines' (PGTLs). This paper investigates backflashover performance of a partial grounding scheme of overhead lines (OHLs) supported by composite pylons. The transient analysis was carried out in PSCAD based on Monte Carlo method. For OHLs with every pylon grounded, reducing footing resistance and soil resistivity can improve backflashover performance effectively, but for PGTLs, these two methods do not have obvious effect and increasing insulation distance has limited effect. When lightning strikes at PGTLs, overvoltage is mainly dependent on the distance to the nearest grounded pylon and a longer distance will cause overvoltage with larger amplitude and longer wave front duration. Therefore, backflashover rate also increases along with the distance to the nearest grounded pylon until reaching a value limited by the inceptive condition of flashover. A coefficient recommended by CIGRE TB 63 to estimate backflashover rate is discussed and modified when using in PGTLs.