Today, there are many attempts to introduce the Internet of Things (IoT) in high-voltage systems, where partial discharges are a focus of concern since they degrade the insulation. The idea is to detect such discharges at a very early stage so that corrective actions can be taken before major damage is produced. Electronic image sensors are traditionally based on charge-coupled devices (CCDs) and, next, on complementary metal oxide semiconductor (CMOS) devices. This paper performs a review and analysis of state-of-the-art image sensors for detecting, locating, and quantifying partial discharges in insulation systems and, in particular, corona discharges since it is an area with an important potential for expansion due to the important consequences of discharges and the complexity of their detection. The paper also discusses the recent progress, as well as the research needs and the challenges to be faced, in applying image sensors in this area. Although many of the cited research works focused on high-voltage applications, partial discharges can also occur in medium- and low-voltage applications. Thus, the potential applications that could potentially benefit from the introduction of image sensors to detect electrical discharges include power substations, buried power cables, overhead power lines, and automotive applications, among others.

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Application of Image Sensors to Detect and Locate Electrical Discharges: A Review

In order to apply photon count parameter to quantitatively determine discharge intensity, taking 10, 35, and 110 kV composite insulators for examples, we investigated the variation of ultraviolet corona discharge photon count due to varying discharge intensity, imager's gain and observation distance, by using a CoroCAM504 ultraviolet imager. The results show that the photon count is approximately linear to the peak value of current pulse peak, and they both increase with the applied voltage. However, the proportion coefficients between the photon count and the current peak are different for the three kinds of insulators. With the increase of imager's gain, the photon count increases firstly, then decreases, and may increase again after the gain getting high enough; moreover, the gain has more influences on the photon count when the observation distance is smaller. Meanwhile, photon count decreases with the increase of observation distance, and the two approximately fits a power function with power-exponent of 1.1~1.6.

Variation Characteristics of Composite Insulator Corona Discharge Photon Count Based on Solar-blind Ultraviolet Imaging Detection

Ultraviolet image has so small target,low contrast image,district characteristic and real-time demand that it is processed by multi-scale morphology filter technology in this paperResults show that the method can enhance target and weaken noiseThe district corona discharged is processed in the paperThe algorithm is easy to deal in parallel and it can be realized easily by hardware

Corona Solar Blind Ultraviolet Image Detecting Method

A real-time high dynamic range intensified complementary metal oxide semiconductor camera based on FPGA

Due to the recent advances of sensing technologies, high dynamic range (HDR) imaging devices have been developed for the image acquisition of real-world scenes with a wide range of luminance changes. In this article, the hierarchical matching techniques for HDR image pairs are investigated. A bit slicing method is combined with the state-of-the-art stereo matching algorithms for HDR images generated from multiple exposures. Our approach demonstrates that it is possible to use only the most significant 16 bits of the HDR image encoding per pixel to achieve a comparable bad pixel rate on stereo matching. Thus, the computational power and memory constraints can be reduced while benefiting from the HDR images. This makes HDR stereo matching feasible under general resource limited setups. In the experiments, the evaluation and comparison carried out using Middlebury stereo datasets have illustrated the effectiveness of the proposed framework. The source codes are available at: https://github.com/chillwater/HDR_Stereo_Match .

Hierarchical Bit-Plane Slicing for High Dynamic Range Image Stereo Matching

To overcome the ghosting phenomenon of multi-exposure technology, a new high-dynamic range (HDR) image processing method is proposed in this paper, which combines the features from dual-gain channel images. Further, a complete CMOS camera based on the HDR method is implemented, which produces a real-time HDR live video streams. This camera can capture the details of bright and dark areas in the scene completely with an extended dynamic range up to 95 dB. An ALTERA FPGA is the core processing unit of the entire camera, and it completes all the functional modules of the camera efficiently, including dual-channel video capture, image caching, HDR synthesis and tone mapping. Finally, the real-time HDR video flow has a display resolution of 1920 × 1080 and a frame rate of 60 fps.

A high-dynamic range CMOS camera based on dual-gain channels

Ultraviolet detection technology, as immediate area of research focus, has been adopted in the fields of fingerprint identification, corona detection and exhaust plume detection. Low-light CMOS, which can work in even 10 -3 lux, is used in visible light channel. The prominent advantage of the dual-channel Ultraviolet/Low-light CMOS camera is the fusion of UV and wide dynamic range visible light information, which can enrich image details and help observers locate the UV targets in the complicated background around the clock rapidly. The paper studied on the component structure of UV ICMOS, imaging driving, the Ultraviolet/Low-light images fusion algorithm and the photon counting algorithm. The one-inch and wide dynamic range CMOS chip with the coupling optical fiber panel are coupled to the UV image intensifier. In consideration of the ultraviolet detection demand, the driving circuit of the CMOS chips is designed and the corresponding program based on Verilog language is written. After analysis and comparison of the characteristics of UV image and Low-light CMOS image, the improved Laplace pyramid fusion algorithm is applied. UV image and Low-light CMOS image are multiscale decompose, and the features in different frequency layer are chosen from either UV image or Low-light CMOS image. The connected components labeling way is utilized for the UV detection and imaging. At last, the detection experiments of the ultraviolet signal are carried out, and the results are given and analyzed.

Xiangyu Kong

Papers

A high-dynamic range CMOS camera based on dual-gain channels

The dual-channel ultraviolet/low light CMOS camera using image fusion technique