Real-time monitoring system for scour around monopile foundation of offshore wind turbine

Abstract

The monopile foundation, as the main form of offshore wind turbine foundations, may be unstable owing to scouring under reciprocating currents; therefore, inspection and maintenance are needed. In contrast to manual inspection, with a real-time monitoring system, the staff can be informed of the safety condition of the wind turbine foundation in real time and maintain it immediately after a system early warning is received. According to the monopile-supported wind turbine of Jiangsu Rudong Offshore Wind Farm Demonstration Project, a blade–tower–monopile–soil coupling integrated numerical model considering scour was established in this study, and scour warning indicators and warning limits related to two aspects—dynamic characteristics and dynamic response—were obtained through calculation and analysis. For the latter, the effect of the wind speed can be excluded by considering the control system. Furthermore, according to the results of the numerical analysis, a real-time safety monitoring system for scouring around a monopile foundation was established in this study, which is composed of data acquisition, data transmission, and data application layers. An inclinometer and accelerometer were selected as sensors. Time- and frequency-domain analyses of the long-term monitoring data revealed a strong annual periodicity (particularly in the east–west direction) in the tower-bottom inclination. According to the proposed early warning indicators, a safety warning was not triggered in this wind farm, and the two early warning indicators exhibited consistent results. The proposed real-time monitoring system can be easily applied to the monitoring of the foundation scouring of other offshore wind farms.