Wind farms run on sensors. They make condition monitoring and SCADA systems possible. Without sensors, no system can be controlled. One pearl of wisdom often dropped by control engineers says that a control is only as good as what it measures, and an event cannot be controlled if it cannot be measured. For wind professionals, the most important sensors are vibration, temperature, and pressure. There are others, such as debris monitors for oil, leak detectors built into seals, and strain gages and algorithms that tell when blades have iced up so turbines can shut down.
Expect to find sensors in more places in part because they are getting cheaper and MEMS manufacturing techniques are making them smaller. In addition, more powerful, less expensive sensors will allow their use in more places than previously possible. Smart sensors will allow making controlbased decisions at nodes, such as turning on devices, flipping circuit breakers, or sending trend data.
Sensors come in all sizes. A laser-based wind sensor, for instance, sits in a pod and mounts to the top of a nacelle to detect wind directions 200 to 300 m ahead of the turbine.
Such sensors can signal adjustments to yaw misalignment. When a turbine runs below rated power, a 10° yaw misalignment reduces power output by about 5%. Sensors (strain gages and controls) that provide data on mass and aerodynamic imbalances allow early action to maximize power generation and avoid damage. Sensors can also tell of damage affecting the structural or aerodynamic performance of a blade, allowing early remedial action.
By identifying small degradations in performance, sensors and software in recent controls can schedule preventive maintenance and even component replacement during scheduled downtime.
Particle sensors look for debris in oil to control contamination. Most use lasers to shine a beam into an oil path to analyze the reflected light by particles. Some have algorithms that discount bubbles in the oil. A few features on one particle sensor includes monitoring contamination trends, and early warning LEDs or digital-display indicators that tell of low, medium, or high contamination levels.
Leak detectors on seals are a recent development. Onboard electronics provide some analysis and can send results to a computer or telephone. This allows remotely monitoring a seal and scheduling an exchange when necessary in a normal maintenance interval. DIN 3760 standards describe function and lifespan for such seals. The sensor-seal combination is available in many different dimensions.
Filed Under: Sensors