Abstract
The blade mass imbalance fault is one of the common faults of the DFIG (Doubly-Fed Induction Generator) wind turbines (WTs). In this paper, considering the spatiotemporal distribution of natural wind speed and the influence of wind shear and tower shadow effect, the influence of blade mass imbalance faults on the electrical characteristics of DFIG WTs is analyzed. Firstly, the analytical expressions and variation characteristics of electromagnetic torque and electromagnetic power under blade mass imbalance are derived before and after consideration of the spatiotemporal distribution of wind speed. Then simulations on the MATLAB/Simulink platform were done to verify the theoretical analysis results. The theoretical analysis and simulation results show that, considering the spatiotemporal distribution of wind speed and the influence of wind shear and tower shadow effect, the blade mass imbalance fault will cause fluctuation at the frequency of 1P (P = the frequency of rotor rotation), 3P, and 6P on electromagnetic power. Fluctuation at 1P is caused by mass imbalance while fluctuation at 3P and 6P are caused by wind speed spatiotemporal distribution; the amplitude of fluctuation at 1P is proportional to the degree of the imbalance fault. Since the equivalent wind speed has been used in this paper instead of the average wind speed, the data is more suitable for the actual operation of the WT in the natural world and can be applied for fault diagnosis in field WT operation.
Highlights
The blade mass imbalance of wind turbines (WTs) is a kind of fault that often occurs in the operation of WTs.WTs mostly operate in outdoor or offshore environments where the environment is relatively harsh, and sand or ice deposits may cause blade mass imbalance
The results showed that electromagnetic power signal contained the first-harmonic component and second-harmonic component of the motor rotation, and amplitude increased as the unbalanced mass increased. [15] was simulated in MATLAB/Simulink, and the output power of the DFIG WTs fluctuated when the blade mass imbalance was verified by the experiment
Equation (17) shows that the fluctuation of electromagnetic torque and electromagnetic power caused by blade mass imbalance fault and equivalent wind speed—including wind shear and tower caused by blade mass imbalance fault and equivalent wind speed—including wind shear and tower shadow effect—will appear at 1P, 3P, and 6P; The fluctuation at 1P is caused by the blade mass shadow effect—will appear at 1P, 3P, and 6P; The fluctuation at 1P is caused by the blade mass imbalance, and the fluctuations at 3P and 6P are caused by the equivalent wind speed
Summary
On the basis of considering the spatiotemporal distribution of practical natural wind speeds, this paper studies the electrical characteristics and the fault diagnosis of the DFIG WTs when there is blade mass imbalance, and finds the fault diagnosis basis to assist the early detection and diagnosis of the fault.
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