Broadband Blended Multitaper Antipodal Vivaldi Antenna for Partial Discharge Detection

Abstract

The electromagnetic ultra-high frequency (UHF) method is gaining popularity due to its noninvasive nature, immunity to low-frequency noise, and fault localization. It has wide applicability in gas-insulated substations (GIS), power transformers, and other power equipment during site acceptance tests or other online diagnostic routines when the usage of standard IEC 60270 method is not possible. In this article, a broadband blended multitaper anti-podal Vivaldi antenna (AVA) having a bandwidth between 500 MHz and 10 GHz is designed and successfully tested for partial discharge (PD) measurement. The antenna design and optimization are discussed, and the results of computer simulations and laboratory measurements are presented. These consist of impedance BW, surface current distribution, group delay (less than 2 ns), and gain in $E$ - and $H$ -planes (ranging from 0 to 9 dBi). Subsequently, the PD detection performance of the proposed antenna is comprehensively verified using a fast pulse generator, corona, surface, and internal cavity discharge. The time-domain waveforms are compared with a commercial horn antenna (used as a reference), and it is demonstrated that the proposed AVA sensor performs at par with the reference. Additionally, separate performance comparisons are carried out with published literature based on antenna and PD detection parameters. It is observed that the proposed PD sensor outperforms others in frequency coverage, fractional BW, gain, and group delay in terms of antenna performance metrics. Moreover, it also displays superior performance in capturing PD pulse rise time with high phase linearity and detection sensitivity. The proposed antenna has the potential to be used in GIS applications as an external sensor placed in front of unshielded observation windows or barrier insulator spacers to detect the leaked PD-induced EM waves.