Doubly-fed asynchronous wind turbine shaft current analysis

Doubly-fed asynchronous wind turbine shaft current analysis - 2019 07 - 21 rui-fang liu Ren Xue jiao Chen Jiayao 1 leads doubly-fed induction generator is one of the current mainstream wind power models, however, the common-mode voltage of the converter by stray capacitance on the motor rotor induction motor shaft voltage and shaft current, caused the bearing early failure, caused by wind turbines down and burned, affects the safe and stable operation of wind power system. Predict double-fed induction wind generator shaft current and look for ways to suppress is of great significance to reduce the incidence of such failures. This paper has established the analysis model of double-fed induction wind generator shaft current, and gives the generator numerical calculation and measurement method of stray capacitance. For a 1. 5 mw doubly-fed induction generator is analyzed, found that only considering the rotor side common-mode voltage of shaft voltage, the influence of shaft current simplified model can be obtained. Shaft voltage sensitivity analysis shows that reducing the stray capacitance between the rotor winding and the rotor core Crwr is an effective way to restrain shaft voltage and shaft current. 2 background bearing inner and outer raceway bearing voltage than the lubricating oil film between the threshold voltage and breakdown occurs, discharge current is produced. Heat released by the instantaneous discharge caused by grease composition denaturation and deterioration and the bearing surface pitting corrosion, lead to bearing failure. Frequency conversion power supply ac motor shaft current problems have long been recognized in the industry application. In the field of new energy power generation, with the widely application of the double-fed induction wind generator, the shaft current problems also appear constantly, through statistical found bearing electric erosion problems in the doubly-fed wind power generator is most serious. 3 papers to solve problems and significance according to statistics, in the 1 ~ 2 mw wind turbine bearing failure accounted for 70%, and wind turbines are installed in high above the ground, the maintenance and overhaul is complex and expensive. So predicting shaft voltage and shaft current of doubly-fed wind power generator bearing corrosion problem of study has important significance. In order to accurately predict the shaft voltage and shaft current, the need to build an accurate analysis model of the motor shaft current. This paper established the doubly-fed asynchronous wind turbine shaft current equivalent analysis model, and put forward based on electromagnetic field numerical calculation and test of motor parameters of stray capacitance extraction method. By testing the shaft electric current of the simplified analysis model, and the capacitor voltage sensitivity analysis was made on the influences of the parameters on the axis, put forward a kind of inhibition of doubly-fed induction generator shaft current of the new scheme. 4 paper method and innovation point 1) By the doubly-fed wind power generator, the distribution of stray capacitance in a complete analysis of doubly-fed induction generator model, as shown in figure 1. Figure 1 doubly-fed induction generator shaft current analysis complete model 2) Put forward the doubly-fed motor stray capacitance calculation and measurement methods. From the perspective of the electric field of the motor there are four parts in the conductor, respectively for the stator winding and rotor winding and the rotor iron core/rotor and stator core/chassis. Based on partial capacitance theory, using the finite element numerical calculation in the stray capacitance motor can be obtained. Actual test, using the capacitance meter two pens and pick any two of four equivalent conductors, measuring the equivalent capacitance between them. Six is obtained by motor stray capacitance distribution circuit equivalent capacitance and stray capacitance relations in motor, for simultaneous solution can be obtained in the stray capacitance of motor. 3) For a 1. 5 mw doubly-fed induction generator is analyzed, found that the doubly-fed induction generator stator side common-mode voltage caused by shaft voltage is very small, can be ignored. So figure 1 model can be simplified, only consider the rotor side common-mode voltage, as shown in figure 2. Figure 2 doubly-fed induction generator shaft current simplified model (4) By stray capacitance on the shaft voltage sensitivity analysis, found the capacitance between the rotor winding and the rotor core Crwr is a key parameter to affect the bearing pressure ratio, as shown in figure 3. Reduce Crwr can inhibit the shaft voltage and shaft current. Figure 3 CRWR and Crf changes for the bearing pressure than five conclusions in this paper the influence of doubly-fed induction generator has established the complete shaft current equivalent model, and gives the motor stray capacitance parameter calculation and testing method. Analysis of the specific example, found that the model only considering the rotor side of shaft voltage, the influence of common-mode voltage can be used to simplify shaft current equivalent circuit analysis. Shaft voltage sensitivity analysis results show that decrease the capacitance between the rotor winding and the rotor core Crwr is inhibition of shaft voltage and shaft current of an effective way. This paper reference: rui-fang liu, Ren Xue jiao, Chen Jiayao. Doubly-fed asynchronous wind turbine shaft current analysis [ J] 。 Journal of electrical engineering technology, 2018 ( 19) : 4517 - 4525. Author introduction: Beijing jiaotong university institute of electrical engineering shaft current research group directed by rui-fang liu associate professor, research the current bear the national natural science fund project shaft current of double-fed induction wind generator bearing damage degree and the development tendency and strategic research (inhibition 51777008). 。 Rui-fang liu female, born in 1971, associate professor, doctoral supervisor, research interests include power electronics and electrical system integration analysis, electromagnetic field theory and numerical calculation. Ren Xue jiao female, born in 1991, master graduate student, research interests include power electronics and motor system integration analysis. Source: journal of electrotechnics