State Monitoring Of Wind Turbine Gearbox Based On Oil Analysis

As a new energy source with mature technology and low cost,the cumulative installed capacity of wind power has been increasing exponentially in recent years.However,the performance of single-unit wind turbines has not been greatly improved.Gearbox is one of the transmission components that causes the whole machine to shut down for the longest time,which is expensive to maintain.Therefore,it is necessary to study the condition monitoring and fault warning technology of wind turbine gear box.At present,the wind turbine gearbox condition monitoring method mainly includes the vibration condition monitoring and the oil condition monitoring,the latter which can reflect the wear condition of the gearbox earliest,this paper mainly researches on the wind turbine gearbox condition monitoring technology based on oil analysis.The paper summarizes the necessity,method and content of oil condition monitoring of wind turbine gearboxes.Through oil off-line analysis method,a more comprehensive and continuous sampling of wind turbine gearbox oil in running is carried out in a wind farm.According to the analysis results,The viscosity of the gear oil has been reduced,the reduction rate of about 3%-9%,water values are below 150 ppm,acid value is between 0.4-0.7mg KOH/g,none of them exceeded the wind power industry experience early warning value.But the pollution degree of the oil sample is higher,the test results show that the pollution degree of most of the gear oil samples has far exceeded the standard value of the ISO pollution degree of the running wind turbine.And the intelligent analysis of the iron spectrum results show that there is a promotion effect between different wear forms.Therefore,it is considered necessary and important for the on-line monitoring of metallic wear debris in the gearbox lubrication system.For the oil on-line wear debris monitoring technology,this subject set up an evaluation test bench for the metallic wear debris sensor,the experiment found that the electromagnetic induction type metallic wear debris sensor used in this experiment can reflect the change trend of the number of metal wear debris in the oil channel more accurately and is more sensitive to the change of the amount of wear debris in the oil,but should pay attention to internal cleaning,select the appropriate flow rate and prevent external electromagnetic environment interference.In the meantime,this paper uses a self-made small-scale gear simulation test stand to study the influence of metallic wear debris with different grain sizes on the wear state of gears.The results show that under the same conditions,the effect of 60-100 um abrasive grain on the wear of gear during the subsequent operation is most serious,0-60 um particle size and 100-200 um particle size secondly.Although the appearance of more than 200 um particles has little influence on the subsequent wear of gear,the appearance of itself has proved that the gearbox has appeared more serious wear.The influence of the particles on the wear of the gear is mainly to promote the generation of the small particle size below 50 um,and then continue to accelerate the wear.The wear forms are mainly in the form of severe sliding wear and fatigue wear.The influences of different particle sizes on the wear are different.Therefore,The method of setting the warning value of the metallic wear debris sensor based on the total amount of the metal particles is inaccurate,and the method of setting the integrated warning value combining different particle sizes and their corresponding numbers should be established.The effect of gear oil on the wear state under different temperatures was studied by using SRV friction and wear tester.The experimental results show that the gear oil temperature has a great influence on the wear state.Under the normal operating conditions of the gearbox,the temperature should be controlled at 25-55 ?,when the temperature reaches above 60 ?,the abrasion of the gearbox may be accelerated due to the destruction of the adsorption layer on the surface of the friction pair.