The development and utilization of clean energy is becoming more extensive, and wind power generation is one of the key points of this. Occasionally, wind turbines are faced with various extreme environmental impacts such as icing, lightning strikes and so on. In particular, the icing of wind turbines increases icing–wind loads, and results in a reduced power output. And blades broken down lead to large-area shutdown accidents caused by high-speed rotating, which seriously affects the reliability and equipment safety of wind power generation. Relevant institutions and researchers at home and abroad have carried out a lot of research on this. This paper summarizes the formation and influencing factors of wind turbine icing, the influence of icing on wind power generation, and defense technologies. First, it introduces the formation conditions and mechanisms of icing in wind farm regions and the relationship between meteorological and climatic characteristics and icing, and analyzes the key influence factors on icing. Then, the impact of icing on wind turbines is explained from the aspects of mechanical operation, the power curve, jeopardies and economic benefits. And then the monitoring and safety status of wind turbines icing is analyzed, which involves collecting the relevant research on anti-de-icing in wind power generation, introducing various anti/de-icing technologies, and analyzing the principle of icing defense. Finally, this paper summarizes wind turbine icing and its defense technologies, and puts forward the future research direction based on the existing problems of wind power generation icing.

With the implementation of West-to-East Power Transmission Project in China, transmission lines will inevitably pass through high altitude regions with complex atmospheric conditions. The effects of such atmospheric parameters as pressure and humidity on the corona discharge performances of conductors are complicated. Especially as to the effect of air humidity on corona inception voltage, researchers have not reached an agreement. Therefore, by adjusting air pressure and air humidity in a corona cage, the positive direct current corona discharge performances of a smooth steel tube are tested. Results indicate that corona inception voltage increases significantly with the increase of air pressure, and the calculated results by discharge model are in accordance with measured results. Yet, with the increase of absolute humidity, corona inception voltage increases slowly. Under high humidity condition, corona inception voltage decreases because of the condensation on conductor surface, which distorts the surface electric field. In view of the condensation, the calculating model is improved, whose calculated results are in line with measured results. Moreover, it is found that inception discharge is easier to turn into glow discharge under low pressure and low humidity condition. The average pulse amplitude decreases with the increase of humidity, but with the increase of pressure, it decreases first and then increases. The rising time of the discharge pulse presents increasing trend with the increase of both air pressure and air humidity. All the test results are analyzed from microscopic mechanism. Copyright © 2013 John Wiley & Sons, Ltd.

The surfaces of lotus leaves with micro- and nano-waxy cuticle structures are superhydrophobic and possess a self-healing ability to regain hydrophobicity after damage. Inspired by this phenomenon, the problem of water-repellent coatings used in natural environments failing to perform after damage can be solved if these coatings are endowed with rapid self-repair and self-growth functions. However, there has been almost no exploration into the hydrophobicity self-repair process in lotus leaves. The changes in surface morphology during the hydrophobicity recovery process are not understood. There is a lack of research on the hydrophobicity recovery in lotus leaves. In this study, the damage and recovery experiments on lotus leaf surfaces were carried out in an artificial climate chamber, and the water repellency recovery process and typical water repellency roughness parameters regained time were obtained. Upon analyzing the differences in the recovery process of different damage types, the recovery mechanism after lotus leaf surface damage was obtained. Finally, it was found that the microscopic roughness determined the static contact angle (WCA) of the lotus leaf surface, and the nanoscopic roughness determined the rolling angle (SA). The dual factors of the recovery of the extruded epidermal tissue and the regeneration of the epidermal wax crystals determined the hydrophobicity recovery process in damaged lotus leaves.

Wind turbines operating in cold regions are more likely to sustain extreme icing, causing the degradation of aerodynamic performance and the loss of wind energy output. This paper proposed a pneumatic impulse deicing method based on the conventional pneumatic deicing boot. This method’s simplified numerical simulation model was built using the commercial software ABAQUS to explore whether this method can deice. After that, experimental investigations were carried out in an artificial climate chamber to verify the deicing performance of specimens using this proposed method. Numerical and experimental results show that the pneumatic impulse deicing method could eliminate the ice layer with a smaller displacement and shorter time than the conventional pneumatic deicing boot. The ice layer’s thickening and inflation pressure enhancement benefit the deicing performance. Experiment results proved that the pneumatic impulse deicing method performs better under inflation pressures of 1.5 MPa and 2.5 MPa with an ice thickness of 6 mm or 8 mm.

Composite insulators are deployed globally for outdoor insulation owing to their light weight, excellent pollution resistance, good mechanical strength, ease of installation, and low maintenance costs. The core rod in composite long-rod insulators plays a critical role in both mechanical load-bearing and internal insulation for overhead transmission lines, and its performance directly affects the overall operational condition of the insulator. However, it remains susceptible to failures induced by complex actions of mechanical, electrical, thermal, and environmental stresses. This paper systematically reviews the major failure modes of core rods, including mechanical failures (normal fracture, brittle fracture, and decay-like fracture) and electrical failures (flashunder and abnormal heating of the core rod). Through analysis of extensive field data and research findings, key failure mechanisms are identified. Preventive strategies encompassing material modification (such as superhydrophobic coatings, self-diagnostic materials, and self-healing epoxy resin), structural optimization (like the optimization of grading rings), and advanced inspection methods (such as IRT detection, Terahertz (THz) detection, X-ray computed tomography (XCT)) are proposed. Furthermore, the limitations of current technologies are discussed, emphasizing the need for in-depth studies on deterioration mechanisms, materials innovation, and defect detection technologies to enhance the long-term reliability of composite insulators in transmission networks.