Evaluation model for immersed tunnel health state: A case study of Honggu Tunnel, Jiangxi Province, China

The icing on overhead transmission lines is one of the largest threats to the safe operation of electric power systems. Compared with other security accidents in the electric industry, a sudden ice disaster could cause the most serious losses to electric power grids. Among the numerous de-icing and anti-icing techniques for application, direct current ice-melting and mechanical de-icing schemes require power cuts and other restrictive conditions. Superhydrophobic coating technology has been widely focused for good anti-icing properties, low cost and wide application range. However, the special structure of curved transmission lines, complicated service environments, and variated electric performance could significantly limit the application of superhydrophobic anti-icing coatings on overhead transmission lines. In particular, superhydrophobic surfaces can be achieved by combining the rough micro-nano structure and modification agents with low surface energy. Compared with superhydrophobic coatings, superhydrophobic surfaces will not increase the weight of the substrate and have good durability and stability in maintaining the robust structure to repeatedly resist aging, abrasion, corrosion and corona damages, etc. Therefore, this review summarizes the theoretical basis of anti-icing behavior and mechanisms, influencing factors of anti-icing properties, potential techniques of superhydrophobic surfaces on transmission lines, and, finally, presents future development challenges and prospects of superhydrophobic surfaces in the anti-icing protection of overhead transmission lines.

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A Review on Superhydrophobic Surface with Anti-Icing Properties in Overhead Transmission Lines

Ice storms have significantly impacted power systems in many ways over the past decades, causing serious damage to power generation, transmission, and distribution assets. Such storms have led to massive and extended power blackouts that have disrupted the lives of many communities, thus raising concerns from several electricity sector stakeholders. This paper aims to provide power grid operators, engineers, researchers, and regulators a comprehensive overview and comparison of the existing short- and long-term planning and operational methods to enhance the resilience of power grids against ice storms. Moreover, the paper also discusses several challenges, needs, and opportunities for future research and development, with a special focus on planning and operation mechanisms for power transmission and distribution network operators.

Enhancing Power Grid Resilience Against Ice Storms: State-of-the-Art, Challenges, Needs, and Opportunities

Ice accretion on transmission lines can cause operational difficulties and disastrous events. In this study, a micro/nano-structured epoxy resin/polydimethylsiloxane (EP/PDMS) film on glass, with water droplet contact angles (CA) observed as high as 160° and the water droplet sliding angle (SA) < 1° was fabricated by aerosol-assisted chemical vapor deposition (AACVD). The glaze icing performance of the superhydrophobic EP/PDMS films have been investigated by comparing the bare glass and room temperature vulcanized (RTV) silicon rubber-coated glass substrate representing the glass insulators and silicone rubber insulators, respectively. Compared with the bare glass and the RTV silicon rubber coating, the EP/PDMS superhydrophobic coating showed excellent performance in delaying glaze icing, especially in the early stages of icing. After 20 min of glaze icing with tilting angle of 90° at −5 and −10 °C, 38.9% and 85.7% of the RTV silicon rubber coating were covered, respectively, and less than 3% of the EP/PDMS coating was covered by ice when the blank glass sheet was completely covered. The EP/PDMS films also showed good mechanical robustness and long-term stability, which are important considerations in their widespread real-world adoption.

The Glaze Icing Performance of a Robust Superhydrophobic Film Composed of Epoxy Resin and Polydimethylsiloxane

Constant use over a period damages the bridge pulling cable structure of pulling sling bridges and reduces their durability. Therefore, a comprehensive and accurate durability evaluation of in-service bridge cable-stayed structures is critical to the safe operation and routine maintenance and repair of pulling sling bridges. In this paper, we first establish a three-layered pulling sling durability evaluation index system and then use the combined IAHP and CRITIC methods to assign weights to these evaluation indexes. The UM theory is applied to calculate a comprehensive multi-index evaluation vector for the durability of the pulling sling, which is evaluated according to the confidence criterion. Taking the Jiahui Bridge tension sling as an example, a durability evaluation was carried out, and the final evaluation result showed the bridge to be at level III, which is in line with the actual situation of the project. Finally, by comparing and analyzing using the SPA and MEE methods, we prove that the durability evaluation results of bridge tension cables using this method are more accurate.

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Evaluation of the Durability of Bridge Tension Cables Based on Combination Weighting Method-Unascertained Measure Theory

Overhead transmission line is the main method of power transmission. Conductors, insulators, and towers are the primary electrical equipment of overhead transmission lines. Due to overhead transmission lines work in the natural environment, problems such as icing, corona discharge, contamination deposition, and corrosion will arise. As a result, some accidents may occur, which cause enormous economic losses. The above problems can be solved by coating functional coatings with superhydrophobic, semiconductive, anti-corrosion, and other characteristics on electrical equipment, which has the advantages of low cost and high efficiency. Therefore, functional coatings have become a research hotspot in the field of external insulation in recent years. In view of the various problems of different electrical equipment in overhead transmission lines, distinctive solutions need to be adopted, so this review classifies the coatings according to the usage scenarios and functions. In each category, first briefly outlines the causes of the electrical equipment problem, then introduces the mechanism of using this type of functional coating to solve the problem, next summarizes the development and application status of this type of coating, after summarizes the limitations of this coating, and finally provides a summary of the key issues in the research of functional coatings and gives an outlook on potential future research directions. This review intends to provide readers with a comprehensive overview of the performance principles and current application status of functional coatings for overhead transmission lines.

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A review on mechanism and application of functional coatings for overhead transmission lines

Considering the corrosion degree of reinforcement, the chloride penetration resistance of concrete and chloride concentration distribution in concrete, a health evaluation method for durability of harbor engineering was established by analytic hierarchy process (AHP). Analysis of a harbor in South China demonstrates that the health indicator for durability condition of existing structures can be effectively used to quantitatively health evaluation for durability of practical engineering.

Bo Xiong Tao

Papers

A review on mechanism and application of functional coatings for overhead transmission lines

Health Evaluation for Durability of Harbor Engineering in South China Based on AHP