Analysis of Weak Section of Submarine Cable inside J-tube of Offshore Wind Farm

Global warming and environmental issues have necessitated ecofriendly energy generation from offshore wind farms. In this context, submarine cables for offshore wind farms and weak sections of the submarine cables inside the J-tube, which transmit power to offshore substations from the wind turbine generator, have been especially researched. The temperature profiles of the cable inside the J-tube of the offshore wind farm are categorized into three sections: section 1 is the high-temperature region exposed to the air. Section 2 is the temperature-change region, where the cable is repeatedly exposed to the air owing to the rising and falling seawater. Section 3 is the-low temperature region because of the cooling effect of the seafloor. We developed an accelerated aging system for submarine cables and used it to evaluate and analyze the aging characteristics of the submarine cables inside the J-tube. This study presents the different temperature profiles of the three sections of a submarine cable inside a J-tube by applying thermal, electrical, and water stress to the test sample using the developed aging system. The experimental results show that the precision of the accelerated aging system was ±1% for 1 cycle. After aging over 60 cycles, the dielectric strength of the insulation in section 2, where the temperature changes were extreme owing to the rising and falling water level, was decreased by 9% when compared with that before aging. Therefore, section 2 is considered the weak section of the J-tube and requires priority monitoring and diagnosis during cable operation.