Tower Vibration-Based Icing Detection on Operational Wind Turbines

Abstract

Ice accretion on wind turbines poses a significant safety risk, especially in densely populated areas. Ice built up on the blades can be thrown towards people and infrastructure and cause potential damage and harm. This risk is known and, as such, several solutions exist in today’s market to detect ice accretion on the blades and timely shut down the system. The industry consensus is that icing detection systems installed directly on the blades offer more reliable detection. However, (post-) installation of hardware on the blades poses some practical limitations, impacting the overall cost and maintainability. To complement existing technology this study proposes monitoring the whirling modes, which are the natural frequencies associated with the wind turbine rotor, through a sensitive accelerometer mounted on the tower. The working principles rely on the concept that the increase of mass due to ice will lower the natural frequencies of the rotor. Observing this phenomenon from the tower implies a similar working principle as some blade mounted systems, while having a sensor installed on the tower simplifies installation and maintenance. Utilizing SHM data from tower, an ice indicator was made during standstill and operation which provided a proof of concept for this method.