Automatic Tracking of the Modal Parameters of an Offshore Wind Turbine Drivetrain System

Abstract

An offshore wind turbine (OWT) is a complex structure that consists of different parts (e.g., foundation, tower, drivetrain, blades, et al.). The last decade, there has been continuous trend towards larger machines with the goal of cost reduction. Modal behavior is an important design aspect. For tackling noise, vibration, and harshness (NVH) issues and validating complex simulation models, it is of high interest to continuously track the vibration levels and the evolution of the modal parameters (resonance frequencies, damping ratios, mode shapes) of the fundamental modes of the turbine. Wind turbines are multi-physical machines with significant interaction between their subcomponents. This paper will present the possibility of identifying and automatically tracking the structural vibration modes of the drivetrain system of an instrumented OWT by using signals (e.g., acceleration responses) measured on the drivetrain system. The experimental data has been obtained during a measurement campaign on an OWT in the Belgian North Sea where the OWT was in standstill condition. The drivetrain, more specifically the gearbox and generator, is instrumented with a dedicated measurement set-up consisting of 17 sensor channels with the aim to continuously track the vibration modes. The consistency of modal parameter estimates made at consequent 10-min intervals is validated, and the dominant drivetrain modal behavior is identified and automatically tracked.

Dynamic Study of a Rooftop Vertical Axis Wind Turbine Tower Based on an Automated Vibration Data Processing Algorithm

“…Since long term monitoring produces a significant amount of data, to facilitate data analysis, the vibration parameters need to be identified using automated procedures. Automated modal analysis procedures based on the stochastic subspace identification (SSI) method were used [33][34][35]. Methods based on clustering adopt a stability diagram; therefore, they can be used concurrently with commercial modal analysis software [33,35].…”

“…Automated modal analysis procedures based on the stochastic subspace identification (SSI) method were used [33][34][35]. Methods based on clustering adopt a stability diagram; therefore, they can be used concurrently with commercial modal analysis software [33,35]. In this study, a new cluster method was adopted for the automated process.…”

Identification of Noise, Vibration and Harshness Behavior of Wind Turbine Drivetrain under Different Operating Conditions

“…The instrumentation was limited to the drivetrain, with 17 accelerometer channels, 14 of which originated from the gearbox. An overview of the measurement set up is given in Reference [10].…”

“…Due to the extreme environment in which wind turbines operate, machines and components are subjected to highly variable operating conditions that cause important mechanical stresses [8]. For this reason, the drivetrain has been already analized for long periods as described in References [9,10]. The referenced works, however, analyze the drivetrain in stand still condition.…”

Health Monitoring and Safety Evaluation of the Offshore Wind Turbine Structure: A Review and Discussion of Future Development

“…In recent years, the OWI-lab also made more contributions to the structural operational modal analysis of OWTs. They tried to construct a complete set of monitoring systems and perfect the automated operational modal analysis method based on the measured data of wind turbines in the Belgian North Sea [115][116][117]. Simultaneously, the comparative studies using different techniques aimed at identifying the modal parameters were presented and the potential benefit of the continued health monitoring and operational modal analysis campaign was discussed [118][119][120].…”