Research On Bearing Shaft Current Damage Of Wind Turbine

Bearing is the key component of the wind turbine, but also easy to damage parts,especially, wind power generator has been in an extreme climate environment for a long time, which has been subjected to a large mechanical load, and bearing is very easy to have mechanical and electrical damage. Because the output voltage of the inverter is in the stator winding of the generator, the common mode voltage can be induced on the motor shaft, and then the axial current is induced. The continuous action of the axial current and the mechanical load caused serious damage to the bearing, which affected the normal operation of the fan. Therefore, it is of great practical value to improve the service life of the bearing of the generator by analyzing the damage mechanism of the bearing shaft of the wind turbine, and the main research is as follows:The mechanism of bearing shaft current generation in wind turbine is expounded.Based on the electrical performance of the wind turbine, integration of the main components of motor bearing, a stator, a rotor, etc. established bearing equivalent common mode circuit model, analysis the shaft current causes and forming process,and the bearing of a wind power generator shaft current simulation modeling and research the operation characteristics of shaft current.Study on the bearing shaft current early damage mechanism. Based on the EHL(Elastohydrodynamic lubrication, EHL, elastohydrodynamic lubrication) of oil film thickness calculation method obtained under different conditions of oil film thickness and the threshold voltage, and analyzes its effect of injury on the shaft current; when the shaft current generated, in the bearing rolling road surface formed of many tiny pitting; based on Hertz contact theory derived formulas for calculation of the number of pitting attack damage, analysis the relationship between bearing early pitting attack damage and the number of axis current, draw inner bearing and an outer roller surface pitting attack damage distribution and analysis of its causes.The formation mechanism of corrugated groove of bearing shaft current damage is proved. Along with the increase of the axial current action time, under the action of external load, a corrugated groove with a certain distance is formed on the bearing roller path. Through the analysis of the formation of the corrugated groove of the bearing factors proposed surface rippled groove width and spacing of the calculation method of roller bearing, obtained under different conditions, bearing rolling bodyand the inner and outer rings of Hertz contact area is different, to the resulting inner raceway and the outer rolling surface formed on the corrugated groove spacing is also different.Analog experiment and analysis of shaft current damage of bearing is carried out.Design of shaft current simulation test-bed of injury, the shaft current damage simulation test, verify the bearing shaft current damage mechanism; analysis test and measurement of the corrugated groove spacing average value and theoretical calculation deviation of a value within the allowable error range, and the outer ring raceway of wave pattern distance slightly larger than the inner ring raceway spacing between the corrugated groove, and theoretical research results are consistent. The test found only in bearing shaft current effect of roll surface can be formed on the washboard shaped rippled groove, no bearing of shaft current role is not the formation of this kind of bearing fault.