With the ongoing rise in renewable energy demand, offshore wind farms are rapidly expanding, increasing the need for advanced development and diagnostic techniques for submarine cables. These cables are essential for efficient and reliable power transmission. A critical issue with these submarine cables is the formation of internal hot spots, which can deteriorate the insulation’s performance and negatively impact the overall reliability of offshore wind energy infrastructure. This research focuses on developing an innovative real-time monitoring system to detect hot spots within submarine cable insulation under varying electrical loads. Experimental tests were conducted on a 66 kV-grade wet-type submarine cable specifically designed for offshore wind applications, applying incremental current loads ranging from 200 A to 500 A. Temperature changes within the insulation due to the generated heat were continuously monitored using Distributed Temperature Sensing (DTS). Additionally, to evaluate the DTS system’s precision, repeatability, and overall reliability, the measured temperatures were compared against values obtained from validated spot-type sensors. Experimental results showed a discrepancy of less than 1% between DTS and spot-type sensor measurements at a reference temperature of 60℃, demonstrating the high accuracy and reliability of the developed DTS-based monitoring system. The outcomes of this study suggest that the proposed monitoring system can significantly enhance the capability for early detection and continuous monitoring of hot spots, thereby improving the operational reliability of submarine cables employed in offshore wind energy installations.

This study investigates the insulation performance of a 66 kV dry-type submarine cable used in offshore wind farms under mechanical aging. During installation and operation, submarine cables are subjected to various mechanical stresses, including tension, compression, and bending, which can lead to insulation deterioration. In this study, XLPE samples extracted from a submarine cable were prepared and subjected to controlled tensile strain below the yield strain to evaluate their mechanical and electrical performance. Changes in tensile strength, elongation, and tan δ (dielectric loss factor) were measured to assess the extent of aging. The results indicate that as the applied strain and exposure duration increased, tensile strength and elongation decreased, while tan δ values increased, signifying a decline in electrical insulation performance. A strong negative correlation (R = -0.809) was observed between tan δ and tensile strength, demonstrating that mechanical aging significantly affects electrical properties. These findings highlight the importance of minimizing excessive mechanical stress during the installation and operation of submarine cables. The results provide valuable insights for enhancing the reliability of submarine cables in offshore wind farms and emphasize the necessity of optimized design and maintenance strategies to mitigate the effects of mechanical aging.

The increasing demand for renewable energy is driving the rapid expansion of the offshore wind industry, leading to intensified research on subsea cables. These cables endure combined thermal, electrical, and mechanical stresses, with mechanical stress being a critical failure factor. Environmental changes, such as seabed scouring, free spans, and seismic activity, accelerate cable degradation by introducing additional dynamic loads. Conventional monitoring systems primarily track thermal stress, lacking the ability to assess mechanical impacts. This study develops a system to simultaneously measure thermal and mechanical stress in subsea cables. Laboratory experiments confirm the system’s reliability, showing a temperature measurement error within 0.8% at 60℃ and a strain measurement error within 13% at 378 με. The proposed system aims to enhance failure prediction and maintenance strategies for offshore wind subsea cables.

With the expansion of offshore wind farms, research on power cables for delivering electricity from offshore to onshore has become increasingly important. In offshore wind farms, submarine cables are introduced and secured to the platform through J-tube conduits. During this process, the cables are exposed to three distinct thermal profiles: high temperatures in the upper section, temperature fluctuations due to water level changes in the middle section, and low temperatures in the seabed region. This study investigates the impact of thermal variations on the insulation performance of submarine cables. To analyze this effect, accelerated aging tests were conducted on both insulation specimens and actual cables. Additionally, dielectric breakdown tests were performed to quantitatively assess insulation degradation. Experimental results revealed that the insulation performance of the specimens exposed to periodic temperature fluctuations due to water level changes deteriorated by up to 7.5%. Based on these findings, the vulnerable sections of submarine cables in offshore wind farms were identified. Furthermore, this study emphasizes the necessity for monitoring and protective measures to mitigate insulation degradation in these critical regions.

Research on aged insulation of cables by stress is constantly being considered for reliable and stable power transmission of offshore wind farms. This study aimed to evaluate the insulation characteristic of aged XLPE (cross-linked polyethylene) insulation for application of offshore wind farms. In this study, The XLPE insulation of cable was set as various mechanical strains. The XLPE insulation is exposed to the mechanical stress below yield strain of 5%, 10%, and 20%. Aged samples were tested by using the method of AC BDV (alternative current breakdown voltage), tensile strength, elongation, and SEM (scanning electron microscope) to obtain insulation characteristics. The experimental results show that the dielectric breakdown of the sample with a strain 20% was 50% lower than the unaged sample; thereby, demonstrating that the mechanical strain that occurred in the submarine cables can weaken the insulation characteristics. Therefore, mechanical strain should be monitored when laying and operating submarine cables for offshore wind farms.

Demand and necessity for eco-friendly offshore wind farms have been increasing. Research on submarine cables is constantly being considered for a reliable and stable power transmission. This study aimed to evaluate the thermal aging characteristic of submarine cables inside the J-tube of offshore wind farms. In this study, a submarine cable was set in three sections: The first is the part exposed to the air above the sea level at high temperature. The second is the section exposed to repeated temperature fluctuation as the sea level rises and falls. The third is the part submerged at low temperature below the sea level. Aged samples were tested by using the method of electrical evaluation to obtain insulation characteristics. The experimental results show that the dielectric breakdown of the sample with temperature fluctuation was 7% lower than the sample with a constant temperature; thereby, demonstrating that the section where the temperature fluctuation occurred in the submarine cables was weaker than the other. The sections of submarine cable with temperature fluctuations are believed as a weak point during operation; therefore, this part should be monitored preferentially.

The wind power generation is an eco-friendly clean energy that produces almost zero CO2emission, and has a good economic feasibility. As for the location, the installation of large turbines and construction of large-scale wind farm is easier on the offshore than on the land. In Korea, it is inevitable to generate offshore wind power through the offshore wind farm, and the radio interference of larger wind power generators and offshore wind power farm to broadcasting, communication and radars is becoming a core issue for constructing the offshore wind farm. In this study, the wind power generation status and rotor blade technology trend were presented, along with the technical trend of radar radio interference reduction relating to construction of the offshore wind farm.