New Technology – Blade vision of SSB Wind Systems enables full-field wind measurement
salt mountains. While the efficiency of a gas turbine, for example, can be determined very accurately, that is until now not possible for a wind turbine. The main reason for this is the discontinuity of the “fuel” wind. Constantly changing wind speeds and directions, vertical and horizontal heavy winds and turbulence makes this fuel unpredictable and therefore ready to date technologies available in a more exact assessment of the performance and the energy yield of a wind turbine major problems. To make matters worse, the current production forecasts involve a number of possible sources of error.
Insufficient data based on wind direction and velocity
The performance of an investment is determined primarily on performance curves. They are based on data from the nacelle anemometer mounted on one and the 10-minute average of the generated power. However, these data (performance-to-wind speed) are ambiguous because the wind measurement is not taken into account by the anemometer wind shear, wind direction and the rotation of the wind direction. The actual efficiency of a wind turbine thus can not be determined in this way. Another problem is the determination of the energy yield. The possible causes for losses in this area are varied and are sometimes insufficient to determine the wind direction by the wind vane. Since the wind vane is mounted on the nacelle behind the rotor blades, it is in a turbulent flow, so that values for wind direction over a longer period must be determined in order to obtain usable data. In addition, the wind vane measures only at a point in the flow field of the swept area of the rotor and therefore can not accommodate all the important data. Add to this the influence of the wind vane by the flow conditions in the engine house itself, which further measurement errors.
Possible sources of error of prediction
24-hour forecasts for the generated amount of energy a wind turbine are divided generally into a weather forecast for the plant site and the calculation of the power output under specific conditions. Forecasts for the next day are mostly based on numerical simulations, which are projected onto a grid whose nodes approximately one to two kilometers apart. An estimated 70 percent of the forecast error may be due to this process, because let passages of weather fronts is very difficult to predict in the forecast area. Around 30 percent of forecast errors can also result from the so-called downscaling, in which the predicted wind direction is transmitted to the nodes on each plant location.
Unique analysis and arguments impossible
Unique and so really accurate statements, whether an investment will perform as promised or whether potential for improvements and optimizations were made, so far as impossible, as an effective root cause analysis to quantify the deficits in the generation of a wind turbine closer. Against this background complicate expected earnings and revenue volatility also the financing of wind farm projects under good conditions.
Journal deformation forms the basis for groundbreaking solution
By a full-field wind measurement with Blade vision of SSB Wind Systems, these problems can now get a grip. The basis for this new development a technology that is based on measurements of the deformation of rotor blades in combination with an advanced signal analysis and evaluation. A digital camera captures here the leaf deformations by recording the deflections of reflectors that are located deep in the interior of the rotor blades. The evaluation and processing of the recorded signals is then carried out in real time on a PC in the turbine building. The system can be averaged over the swept area of the rotor blades, measure the wind with an accuracy that is comparable to a tire mounted on a rotor blade hub LIDAR. Here, both wind speed, wind direction, rotation of the wind direction, vertical and horizontal wind shear and vertical wind speeds and turbulence up to 0.03 Hz are measured. Wind signals are averaged for a period of 15 seconds, the wind allow convection corresponds approximately to the equivalent to the rotor diameter, which is determined every second. The bending moments that occur during each revolution of the rotor blades are calculated every 50 milliseconds.
More accurate performance curves
Blade vision enables an immediate and full wind field measurement and thus creating much more precise power curves. Based on the information on the complete wind field conditions not only the wind speed, but particularly factors such as wind shear, turbulence level and the wind direction at the time of power are determined. This allows the power measured according to the factors listed in categories divide, and represent each categorized wind field condition in power curves. The result is a unique power curve based on 15-second data instead of 10-minute data, and thus the current efficiency of the system much better description.
Actual efficiency of a wind turbine determine
The accuracy of a clearly defined power curve and the knowledge of all prevailing wind field conditions during the measurement thus make it possible to assess the actual efficiency of a wind turbine. About accurate performance curves, a higher energy production and improved 24-hour forecasts addition is realized by Blade vision of SSB Wind Systems also a more accurate condition monitoring of rotor blades. (Press release dated 01/10/2014)
Source: SSB Wind Systems GmbH & amp; Co. KG | Photo: SSB Wind Systems