Papers by Author: Ming Qin

Abstract: Wind turbine generator (WTG), with a large inertia in the time-domain, has a significant restraint to the high-frequency fluctuations of the wind speed. When analyzing and modeling the wind turbines electrical and controlling processes, its needed to quantify or estimate this inhibition. To estimate the WTGs inertia parameters, a digital filter is introduced to approximate the inertia transfer model of WTGs blade, drive chain and the generators rotor, by analyzing the correlation of the filters output and the generators rotor speed, the time window with the best correlation probability is selected as the restraint performance indicator of the blade, drive chain and generators rotor. The proposed method is finally verified by the simulation using the SCADA data.

Abstract: A gearbox condition assessment method for the Wind Turbine Generator (WTG) is proposed. Vibration signal’s Intrinsic Mode Functions (IMF) are decomposed by Empirical Mode Decomposition (EMD). Normalized Hilbert-Huang and Direct Quadrature (DQ) method are used to determine the instantaneous frequency. The HHS of vibration signals is plotted and then is shifted to match the pre-defined faulty gear condition by the Iterative Closest Point (ICP) algorithm to diagnose their similarities. The principle and effectiveness of the proposed method are illustrated by simulation, the fault types of gearbox can be identified by ICP algorithm effectively.

Abstract: To enhance heat exchange between the rotor and external environment, many ribs are arranged on the cover of the machine. The air cooling condition for 1.5MW wind rotor is evaluated by Computational fluid dynamics(CFD). It is found that the density of the air, the flow velocity and the arrangement of the ribs on the rotor cover is the main factors impacting the air cooling effect of the rotor. Under the same running power, the air cooling condition becomes worse with the decrease of air density and becomes better with the increase of wind speed. To improve the cooling condition of the wind rotor, the arrangement of the ribs on the cover is optimized. The results show that the width ratio of the ribs and channels plays an important role in the heat convection. In all our cases, 0.5 is the best. Considering the manufacture processing, the arrangement of 400 ribs is selected in our optimization.

Abstract: The water cooling system of 1.5MW rotor is evaluated using Computational Fluid Dynamics (CFD). 48 cooling holes are opened on the rotor stator to arrange the water cooling pipes, the temperature of inlet of the cooling water is 50 C with the velocity 1.2m/s. It is found that the air gap between the cooling pipes and holes on the stator hinders the heat exchange extensively. For this reason, the cooling system can't meet the design requirement. In order to solve this problem, the pourable silicone is filled in the gap between the cooling pipes and holes to enhance thermal conductivity. Based on this idea, ten kinds of piping arrangements are proposed, among which, nine kinds can achieve the cooling requirement.

Abstract: With the large-scale direction development of wind turbine, the vibrations of wind turbines, which are rigid-flexible coupled multi-body systems, can be easily excited. Control system can be improved to reduce the vibration amplitude and load levels. Fluctuation-suppression pitch control strategy has been improved in this paper. The reference input rotation speed, which is normally constant, is required to change with rotation acceleration in pitch control in this new control strategy. Theory and simulation show that Fluctuation-suppression pitch control (FSPC) strategy can improve the vibration characters of wind turbine and suppress rotation speed and power fluctuation, and it is also quite effective for gust situation