Inductive proximity sensor in wind turbine can control the yaw angle and yaw rotation direction well in the yaw system, which greatly improves the wind energy utilization rate of wind turbines. Inductive proximity sensors play an important role in wind turbine speed control in terms of safe operation.
Proximity sensor in wind turbine : With the improvement of people’s understanding of the value of renewable energy use and the continuous progress of wind power unit manufacturing, control and other related technologies, wind power generation has developed very rapidly in the past decade.
At the same time, the single unit capacity of wind power units and the total installed capacity of wind farms are also increasing, so the wind energy utilization rate and safe operation of wind farms have also attracted more and more attention.
How proximity sensor in wind turbine works ?
A proximity sensor can detect metal targets close to the sensor without actual contact with the target. Its characteristics are: non-contact detection, which avoids damage to the sensor itself and the target; no contact output, long operating life; stable detection even in harsh environments with water or oil splash; fast response speed; small sensor, flexible installation; can be used as limit, count and positioning control in the automatic control system. and automatic protection link.
Inductive proximity sensors mainly use the mutual inductance principle of metal conductors and alternating electromagnetic fields. Metal materials that can attenuate the magnetic field will produce eddy currents, which will attenuate the energy of the magnetic field and reduce the amplitude. This change in the inductive proximity switch will reverse the corresponding output level.
The inductive proximity sensor consists of high-frequency oscillation, detection, amplification, trigger and output circuits. The oscillator produces an alternating electromagnetic field on the sensor detection surface. When the metal object approaches the sensor detection surface, the eddy current generated in the metal absorbs the energy of the oscillator, weakening the oscillation and even stopping the vibration. The oscillation and stop of the oscillator are converted into electrical signals through shaping amplification and converted into binary switching signals, which are output after power amplification.
Application of proximity sensor in fan yaw
- Introduction to yaw system
The yaw system of the fan is one of the indispensable components of the horizontal axis megawatt-class wind turbine. Its main functions are as follows:
(1) The yaw system can adjust the cabin at any time according to the change of wind direction to keep the impeller at the wind direction, so that the wind turbine is always in the wind state.
(2) it has the yaw brake function and provides the necessary lock. Tight torque to ensure the safe operation of wind turbines.
(3) When the wind turbine is due to yaw action, the cables connecting the engine room to the electrical equipment inside and under the tower will be torsioned and wind, and the winding can seriously damage the cables. When the winding reaches a certain extent, the yaw system can automatically unwind the cable. That is, when the cumulative yaw in a certain direction reaches 720 degrees, the control system will start the automatic unwinding program to avoid the danger of the cable due to excessive new dens.
2. Application Principle of Proximity Sensor in Fan Aw
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The yaw operation sequence of wind turbines is roughly summarized as follows: the wind direction is detected through the wind sensor, and the detected wind direction signal is sent to the main control system. The main control system calculates the angle between the wind direction and the cabin position, so as to determine whether the cabin direction needs to be adjusted and which direction can be adjusted to aim at the wind direction as soon as possible.
When it is necessary to adjust the direction, the main control system sends a signal to the yaw drive mechanism to adjust the direction of the cabin, so as to aim at the wind direction. In this yaw process, the proximity sensor outputs the signal to the main control system, which judges the direction of the yaw rotation and calculates the yaw angle. When the wind is over, the yaw motor stops rotating and the yaw process ends.
We choose the appropriate proximity sensor in wind turbine according to the on-site installation conditions and the speed of the yaw large gear ring. When selecting, pay attention to frequency matching. The frequency of the detected target should be lower than the maximum induction frequency of the proximity sensor, and the material of the detected target should be within the sensing range of the proximity sensor.
Two proximity sensor in wind turbine are installed on the outside of the large gear ring of the yaw bearing. Adjusting the back tighten nut can adjust the distance between the proximity sensor and the top of the yaw gear ring. When installing, the sensor sensor surface should be perpendicular to the gear plane.
The metal gears, tooth grooves and other moving parts of the measured gear ring pass through the front end of the sensor, causing the corresponding change of the magnetic field and making the output pulse signal of the proximity sensor different.
The main control system calculates the yaw angle by collecting the pulse signal and controls the unit’s yaw not exceeding 720 degrees to prevent the cable from being over winded. Through the signals sent by two proximity sensors on one left and one right, the main control system can determine the yaw rotation direction of the yaw system.
There is an indicator light on the proximity sensor in wind turbine. When there is a signal output, the indicator light will be on. When approaching a certain distance, observe whether the indicator light is on. If the indicator light is on, it means that the sensor can work normally.
Application of proximity sensor in wind turbine speed control
- The harm of excessive wind turbine speed
The fan transmission chain includes spindle components, gearbox, couplings, brakes, generators. The wind-blown wind turbine rotates through the spindle to the gearbox, and the low-speed shaft speed is converted into a higher generator speed through the gearbox.
Wind turbine speed and power increase with the increase of wind speed, but excessive wind speed will lead to excessive wind turbine speed and generator overload. In the case of strong wind, the fan is also easy to cause the flying car to lose control and endanger the operation safety of the wind turbine. Therefore, the speed control of wind turbine is particularly important proximity sensor in wind turbine.
2. Principle of wind turbine speed control
We can use proximity sensor in wind turbine to sense the speed of the low-speed shaft. If the speed of the low-speed shaft is too high, we can alarm and then brake.
A proximity sensor in wind turbine is installed at the low-speed shaft of the gearbox. There are a certain number of bolts on the low-speed shaft compaction disk. When there is a bolt surface close to the sensor sensing surface, the proximity sensor will send a pulse signal to the speed relay.
After the speed relay converts this pulse signal into an analog quantity, it is transmitted to the main control system, which is transmitted by the main control system. The rotor speed of the gearbox low-speed shaft is judged. When the speed exceeds the set value, it will cause the unit to stop and ensure the safe operation of the unit.
Overspeed relay is a pulse evaluation system. It receives pulses from a proximity sensor at the low-speed axis, measures the pulse time interval, and calculates the input frequency. Compare this value with the set switch point and turn on the output according to the set parameters. An integrated frequency-current converter converts the input frequency into an analog signal.