In this paper, the design and development of a bio-inspired UHF sensor for partial discharge detection in power transformers is presented. The UHF sensor was developed for external use in dielectric windows of power transformers. For this purpose, a microstrip antenna was designed with a radiating element shape based on the leaf of the Jatropha mollissima (Pohl) Baill plant. Then, an epoxy coating and an aluminium enclosure were developed to protect the antenna against corrosion and to provide mechanical support, external noise immunity, and a lifetime compatibility with power transformers. In order to verify the electrical parameters of the developed sensor, measurements of the gain and the reflection coefficient were performed in an anechoic chamber. Lastly, the antenna sensitivity for denominated partial discharge (PD) detection was compared with the IEC 60270 standard method. For this purpose, simultaneous tests were carried out in a partial discharge generator setup, composed of an oil cell with needle-plane electrodes. The experimental tests demonstrated the effectiveness of the sensor for detecting PD signals with apparent charge values higher than 35 pC.

In this paper, a biologically inspired design methodology to develop directional leaf‐shaped printed monopole antennas (PMA) for applications in the fourth‐generation (4G) of mobile telecommunications technology is presented. Bio‐inspired in the leaf shapes of a sugar cane plant, compact directional PMA are designed (with partial ground planes and flat rectangular reflectors) to cover the Brazilian 4G 700 MHz regulated band (698–806 MHz), with broadside radiation patterns and maximum directive gain up to 7.7 dBi. Simulated and measured results are presented for the proposed leaf‐shaped antenna prototypes, and obtained results are compared with a square PMA. The use of bio‐inspired leaf‐shaped radiators and flat reflectors provides a fine tuning of ultra‐wideband commonly presented by a conventional PMA, and the lowest resonant mode can be adjusted to cover the 700 MHz band. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1529–1533, 2016

Wearable antennas present flexible dielectric and microstrip antenna normally used in Wireless Body Area Network systems with medical and no‐medical applications. This article presents a new wearable printed monopole antenna for second generation (2G), third generation (3G), and fourth generation (4G) systems on textile material and laminate cooper to flat cable. The bioinspired geometry of a gynkgo biloba leaf was generated by Gielis formula. The proposed antenna presents a bandwidth of 2.70 GHz, covering the ranges of 2G, 3G, and 4G systems, with an omnidirectional radiation pattern, 3.10 dBi gain, and a HPBW of 102°. Measurements were performed with the antenna nearly on the head, on hand and in the pocket of trousers. The biggest difference, in the resonance frequency, was observed with the antenna on hand, and the antenna nearly on head, showed greater difference in bandwidth. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2818–2823, 2016

A new, bio-inspired printed monopole antenna (PMA) model is applied to monitor partial discharge (PD) activity in high voltage insulating systems. An optimized sensor was obtained by designing a PMA in accordance with the characteristics of the electromagnetic signal produced by PD. An ultra-wideband (UWB) antenna was obtained by applying the truncated ground plane technique. The patch geometry was bio-inspired by that of the Inga Marginata leaf, resulting in a significant reduction in size. To verify the operating frequency and gain of the PMA, measurements were carried out in an anechoic chamber. The results show that the antenna operating bandwidth covers most of the frequency range of PD occurrence. Moreover, the antenna presented a good sensitivity (mean gain of 3.63 dBi). The antenna performance was evaluated through comparative results with the standard IEC 60270 method. For this purpose, simultaneous tests were carried out in a PD generator arrangement, composed by an oil cell with point-to-plane electrode configurations. The developed PMA can be classified as an optimized sensor for PD detection and suitable for substation application, since it is able to measure PD radiated signals with half the voltage levels obtained from the IEC method and is immune to corona discharges.

This paper presents an algorithm for the localisation of partial discharge (PD) sources in power transformers based on the electromagnetic waves radiated by a PD pulse. The proposed algorithm is more accurate than existing methods, since it considers the effects of the reflection, refractions and diffractions undergone by the ultra-high frequency (UHF) signal within the equipment tank. The proposed method uses computational simulations of the electromagnetic waves generated by PD, and obtains the time delay of the signal between each point in the 3D space and the UHF sensors. The calculated signals can be compared with the signals measured in the field, so that the position of the PD source can be located based on the best correlation between the simulated propagation delay and the measured data. The equations used in the proposed method are defined as a 3D optimisation problem, so that the binary particle swarm optimisation algorithm can be used. To test and demonstrate the proposed algorithm, computational simulations were performed. The solutions were sufficient to identify not only the occurrence of defects, but also the winding and the region (top, centre or base) in which the defect occurred. In all cases, an accuracy of greater than 15 cm was obtained for the location, in a 180 MVA three-phase transformer.