In China, nearly 10000 units of doubly fed wind turbines have experienced varying degrees of high oil temperature alarm faults in their gearboxes, which basically cover all doubly fed wind turbines. The high oil temperature faults in the gearboxes have brought many challenges to the daily operation and maintenance of wind farms.
1. The current situation and hazards of high oil temperature faults in gearboxes
The doubly fed unit is the mainstream model of wind power generation, and the gearbox is one of the most important and valuable components of the doubly fed wind turbine. The operational stability of the gearbox is crucial for the stable operation of the wind turbine, and the normal operation of the lubrication system is a critical factor for the long-term operation of the gearbox. With the extension of running time, many gearbox cooling systems of doubly fed fans have gradually encountered the problem of high oil temperature. After cleaning and repairing the heat sinks, the problem of high oil temperature in the cooling system still cannot be completely solved.
(1) Power limited operation: Gear oil overheating causes the fan to operate at limited power or shut down due to overheating, resulting in serious loss of power generation and affecting the economic indicators of the fan.
(2) The service life of lubricating oil is shortened: According to research by professional institutions in the industry, for every ten degrees increase in gear oil temperature, the service life is nearly halved. Long term operation of lubricating oil in high temperature environments can lead to accelerated oxidation, blackening, increased viscosity, precipitation, and corrosion of tooth surfaces.
(3) Affects the overall ventilation capacity of the cabin. Excessive oil temperature can cause the cabin temperature to be significantly higher than the ambient temperature, making the components in the cabin more prone to aging and causing other malfunctions. During the high temperature period in summer, various electrical equipment failures occur frequently in the fan. pln ple
2. Analysis of the causes of high oil temperature faults
(1) The regulating device of the circulatory system is malfunctioning. This type of malfunction is often caused by damage to control valves such as temperature control valves. The flow of lubricating oil through the cooler decreases, and the oil does not cool sufficiently before entering the gearbox for lubrication. The accumulation of heat ultimately leads to the gearbox oil temperature exceeding the limit fault.
(2) The operating conditions of the gearbox deteriorate, the wear of the gear mechanism intensifies, the transmission efficiency decreases, and the overall heat generation of the equipment increases. This type of malfunction often occurs in equipment where the viscosity temperature characteristics of lubricating oil deteriorate and the operating efficiency of gear mechanisms decreases.
(3) After the cooler is blocked, the cooling capacity does not meet the cooling load requirements, and the heat exchange capacity of the cooler decreases. This type of malfunction is very common, mainly because some brands use high resistance external fins, which have the advantages of compact structure and high heat transfer efficiency, but the disadvantages are complex structure, high internal resistance, and easy blockage.
(4) Oil and air pollution in the cabin caused blockage of the cooler. This phenomenon is a common problem in the operation of wind turbines. The air quality in the construction area of wind power projects cannot achieve sufficient cleanliness, and there will inevitably be dust and plant-based fibers. At the same time, there is oil leakage in the gearbox, and various oil stains leaked in the cabin will gradually evaporate into oil and gas, which will be sucked in by the cooler. When mixed with dust, it is easy to cause blockage of the wing passage.