Wind Turbine Blades as a Strain Energy Source for Energy Harvesting

Abstract

Structural health monitoring of wind turbine blade mechanical performance can inform maintenance decisions, lead to reduced down time and improve the reliability of wind turbines. Wireless, self-powered strain gages and accelerometers have been proposed to transmit blade data to a monitoring system located in the nacelle. Each sensor node is powered by a strain Energy Harvester (EH). The amplitude and frequency of strain at the blade surface (where the EH is mounted) must be sufficient to enable data transfer. In this study, the strain energy available for energy harvesting is evaluated for three typical wind turbines with different wind conditions. A FAST simulation code, available through the National Renewable Energy Lab (NREL), is used to determine bending moments in the wind turbine blade. Given the moment data as a function of position along the blade and time (i.e. blade rotational position), strain in the blade is calculated. The data provide guidance for optimal design of the energy harvester.

Wireless monitoring algorithm for wind turbine blades using Piezo‐electric energy harvesters

“…The residuals (23) and (31) take a similar form as that given in Equation (7). Figure 3 shows a sample case of the three energy residuals calculated from experimental strain data ( 300 amplitude at 0.2 Hz for a 2.5 MW turbine 18 ) such as subplots in the top of Figure 1. In the sample figure, the residuals are shown as if blade 3 is damaged and blades 1 and 2 are healthy.…”

“…The load magnitude is such that strain amplitude zz at the root of the beam is approximately 400 -strain-a strain level comparable with strain that occurs for full scale wind turbines under operational conditions. 18 The model output includes stresses, strains, rotation and displacement at all element nodes. Figure 4 shows the strain amplitude of a damaged beam along the length of the beam for the case where the damage area is 1 m 1.1 m and the extent of damage ratio E 0 E is 0.6.…”

“…In our prior work, 18,19 we demonstrated that the low frequency strain energy associated with turbine blade flexure is sufficient to power a wireless strain sensor node. The strain sensor node is comprised of a PZT energy harvester (EH), capacitor and telemetry unit.…”

Wireless Structural Health Monitoring of Wind Turbine Blades Using an Energy Harvester as a Sensor

“…In our earlier work 15 , the strain energy available was estimated for three wind turbines (a CART3 600 kW, a WindPact 1.5 MW and a 5MW offshore wind turbine) and various wind conditions (6 to 24 m/s at high and low turbulence). For the range of wind turbine sizes and wind conditions considered, the P avail ranges from 1 to 30 W/m 3 .…”

A novel method for autonomous remote condition monitoring of rotating machines using piezoelectric energy harvesting approach

“…Moreover, in some studies, it was shown that a wireless connection can be powered by these self-powered sensors for transferring data or sending a pulse [18], [19]. In the research by Lim et al [20], piezoelectric patches were installed on wind turbine blades to demonstrate that the patches can provide power for wireless connection from blade strain energy. In the existence of a structural imperfection or a fault in the system, introduced vibration on these smart materials will be different and, hence, this concept can be used for condition monitoring or structural health monitoring.…”