In order to assist a system design of laser coherent Doppler wind sensor for active pitch control of wind turbine systems
(WTS), we developed a numerical simulation environment for modeling and simulation of the sensor system. In this
paper we present this simulation concept. In previous works, we have shown the general idea and the possibility of using
a low cost coherent laser Doppler wind sensing system for an active pitch control of WTS in order to achieve a reduced
mechanical stress, increase the WTS lifetime and therefore reduce the electricity price from wind energy. Such a system
is based on a 1.55μm Continuous-Wave (CW) laser plus an erbium-doped fiber amplifier (EDFA) with an output power of 1W. Within this system, an optical coherent detection method is chosen for the Doppler frequency measurement in megahertz range. A comparatively low cost short coherent length laser with a fiber delay line is used for achieving a multiple range measurement. In this paper, we show the current results on the improvement of our simulation by applying a Monte Carlo random generation method for positioning the random particles in atmosphere and extend the simulation to the entire beam penetrated space by introducing a cylindrical co-ordinate concept and meshing the entire volume into small elements in order to achieve a faster calculation and gain more realistic simulation result. In addition, by applying different atmospheric parameters, such as particle sizes and distributions, we can simulate different weather and wind situations.
With the availability and maturity of scanning micromirrors, a growing field of applications other than picoprojectors is
emerging. The miniaturization potential of these scan based setups is most attractive for robotic vision and LIDAR
imaging sensors for autonomous guided vehicles. The laser safety concept of picoprojectors is based on the eye blink
reflex and high scanning frequencies (<10 kHz). However, in remote sensing applications, where infrared wavelengths
and very often lower scanning frequencies are a common choice, there is a demand for robust scan failure detection.
According to IEC 60825 the maximum emission time of a 100 mW CW Laser at 900 nm must be below 5 μs to be
classified as a class 1 laser source. State-of-the-art scan-fail devices, which are designed for laser light shows, only
feature reaction times down to 1 ms. Therefore, to enable class 1 operation of a laser scanner, based on micromirrors, a
detailed examination of all possible failure scenarios was performed and consequently a fast scan-fail device with a
reaction time of less than 5 μs was developed. The position of the micromirror is measured optically by focusing a laser
diode to the micromirror and detecting the mirror position with a quadrant photodiode. To determine the current angular
velocity of the micromirror the first derivative of the position signal is evaluated and monitored. This enables the eyesafe
use of reasonably powered infrared lasers in low-cost scanning setups.
A low cost design concept for Fibre-based Coherent Laser Doppler Wind Profiler is presented for supporting an active
pitch control of Wind Turbines (WTs). The system is based on a 1.5μm Continuous-Wave (CW) semiconductor laser
source plus an erbium-doped fibre amplifier (EDFA) with an output power of 1W. A coherent detection method is used
for Doppler frequency measurement. In addition, a concept of wind turbine predictive pitch control system is proposed
for reducing the damage caused by wind turbulence. A mathematical simulation and the experimental result based on a
lab setup are presented to show the calibration of such a system.