Analysis and prevention of the pitching system
The structure and working principle of the pitch system of the wind turbine can cause the following three reasons:
1) Reasons for the battery: It can be concluded from the structure of the pitch system that when the fan is stopped due to sudden failure, it is completely dependent on the battery in the hub to receive the paddle. Therefore, the battery in the hub has insufficient energy storage or the battery is de-energized, so that when the fault occurs, the paddle cannot be returned in time, and the speed is caused. There are two main aspects of battery failure: the damage to the battery charger at the front end of the battery causes the battery to fail to charge until the loss; due to the quality problem of the storage itself, if there are 1-2 batteries in the group, the battery is lost. The voltage measurement is in the normal range, but the battery cell voltage is not normal after the measurement. This battery can not provide normal electric drag force after the failure, which effectively promotes the recovery of the blade, and eventually causes a speeding accident.
2) Reasons for the signal slip ring: Most of the pitch communication failures of this type of fan are caused by poor contact of the slip ring. When the gearbox leaks seriously, the oil enters the slip ring. The oil adheres to the oil film between the slip ring and the pin, which acts as insulation, causing the pitch communication signal to be intermittent, causing the control unit of the main control cabinet to accept and feedback. Dealing with the overspeed signal, the pitch system can not be stopped until the speeding; due to the internal structure of the slip ring, the slip ring track and the probe are in poor contact, which may also cause signal interruption and delay, which does not rule out The needle will be deformed by force.
3) Reasons for the overspeed module: The main function of the overspeed module is to monitor the overspeed of the low speed shaft and blades of the main shaft and gearbox. The module is to monitor the three speed measuring points of the shafting system at the same time, and judge the overspeed state of the shafting system by taking the three logic mode. The three-take two overspeed protection action has an independent signal output that directly drives the device action. With two channels of cooperation, the measurement of the direction of rotation of the shaft and the speed of rotation can be completed. Two gears with phase offset are generated by using a toothed disc with a certain pitch requirement. The phase shift between the A channel monitoring signals obtains the rotation direction, and the B channel monitors the signal cycle time to obtain the rotation speed. When the module software fails or there is a problem with the signal perception, it will cause the fan master to judge the fault and stop in time when overspeeding, which will lead to the speeding.
In order to prevent the occurrence of pitching system accidents, we should take prevention as the main method. The prevention methods are as follows: periodically check the battery cell voltage, periodically perform battery charge and discharge experiments, and control the battery detection time in a reasonable interval. Pay close attention to the power supply quality of the power grid during the process, minimize the impact of large voltage on the hub charger and UPS, avoid unnecessary damage of components as much as possible; thoroughly eradicate the shortcomings of gearbox oil leakage, and regularly carry out the cleaning work of the slip ring. Ensure the normal operation of the slip ring; specifically test the function of the overspeed module KL1904 to avoid the formation of soft faults of the module.
