An Imaging Method for Partial Discharge Electromagnetic Signal Based on Polyhedral Sensor Array

Defects and hidden dangers of power equipment can be detected in advance by detecting the partial discharge (PD), and equipment failures and unexpected power outages could be avoided. Therefore, accurate orientation for PD is very important. However, time-delay-based PD electromagnetic signal orientation methods mainly rely on high-frequency sampling systems and high-precision synchronization performance, resulting in high hardware costs and relatively heavy devices. The existing methods based on the amplitude of ultrahigh-frequency (UHF) signal could only be used for 2-D orientation, which is hard to meet the application needs in actual 3-D field situations. Therefore, this article proposed an RSSI-based 3-D PD orientation method for electromagnetic signals, combining the visual image to generate a WYSIWYG detection of PD. First, based on the directional characteristics of the UHF sensor, a regular dodecahedron array structure was designed by simplifying a complex spherical structure. Then, a 3-D orientation model based on the amplitude of UHF signals was established, which included four variables: elevation angle, azimuth angle, maximum amplitude, and attenuation rate. Three-dimensional orientation results were obtained by solving the equation set. The cluster analysis was next employed for multiple 3-D orientation results to obtain the final accurate result. Finally, the accuracy of the proposed method was verified with experimental tests, and then, combined with the video, a PD imaging system was mounted on the UAV for a field test to verify the effectiveness of the actual defect.