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The damage detection of the wind turbine (WT) blade is an important aspect of its health situation monitoring. In order to catch small damages, it is necessary to stitch the multi segment images of the blade to obtain a high resolution image. In image stitching, a blurring of the image is carried out to reduce the influence of noise. However, the preprocessing may decrease the amount of feature points and cannot avoid the interaction of feature points in the background and the target parts. To overcome these problems, a preprocessing method based on background removal is proposed. The idea of the method is to carry out image segmentation to get the background part, then the intensities of pixels in background part are replaced by a same value, such as average intensity. Employing the proposed preprocessing method, the image stitching is implemented on several groups of WT blade images. Feature points extraction result are compared between the proposed and the blurring preprocessing, which shows that the proposed method is more robust to the parameters in image stitching process. Moreover, the capability about image stitching and multi-image stitching of the proposed method is well verified by the experiment results.

Wind energy, as a renewable energy source, has attracted great attention of many countries. It is converted into electricity by the important machine, wind turbine (WT). With the fast growing of WT capacity in the world, the costs of monitoring and maintaining increase year by year. One necessary part of these costs is for blades health situation monitoring, which directly affects effectiveness and safety of WT. Thus, the damage detection of the blades is of great significance. The blades suffer from sunshine, acid rain, sand attack, and others, which may cause kinds of damages, such as skin abscission, surface crack, and sand hole. Aiming at surface damage detection of the blades, the paper proposed a method based on variational image segmentation model. At beginning, an idea that objects in an image are left along with detection of the background part is present, and it is changed into an optimization problem by using the level set method and 1-D Heaviside function. Then the corresponding gradient descent minimization algorithm is derived. In the experimental part, a large number of blade images with surface damages are tested by applying the proposed method, and damages are all detected successfully. Moreover, the segmentation results of the noise images show that our method is robust to noise. This paper can provide effective technical support for surface damage detection of WT blades in-service.

The rapid and accurate detection of partial discharge (PD) in AC metal enclosed switchgear (switchgear cabinet) is of great significance to ensure the safe operation of power grid and improve the reliability of power supply. At present, the main methods used to detect PD signal in high voltage (HV) switchgear cabinet are transient earth voltage (TEV), ultra high frequency (UHF) and ultrasonic emission (AE). Based on a simple comparison of the above three methods, this paper reviews the TEV detection method which is widely used and has formed many standards. The physical principle, instrument composition and requirements of TEV detection method and field technical standards are summarized. The related applications including comprehensive application analysis, multi-technologies joint detection, discharge power verification and positioning, PD transmission simulation and robot application are introduced. Finally, the technology prospect of integrated composite sensor and Internet of things (IOT) is given.

Each magnetic field power supply is consists of three-phase full bridge thyristor converters on HL-2A Tokamak. To enhance and improve the performance of the control system of power supply system, a varying frequency three phase signal circuit has been design based on digital signal processor, which was used to control power supply on HL-2A Tokamak. This synchronous system has many advantages and is successfully applied to the operation of the power supply system in plasma discharge.