A Novel Diagnostic Feature for a Wind Turbine Imbalance Under Variable Speed Conditions.

Dependency between the conventional imbalance diagnostic feature and the shaft rotational speed makes imbalance diagnosis challenging for variable-speed machines. This paper focuses on an investigation of this dependency and on a proposal for a novel imbalance diagnostic feature and a novel simplified version for this feature, which are independent of shaft rotational speed. An equivalent mass-spring-damper system is investigated to find a closed-form expression describing this dependency.