RESUMO
This paper presents an algorithm for the localisation of partial discharge (PD) sourcesin power transformers based on the electromagnetic waves radiated by a PD pulse. The proposedalgorithm 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 equipmenttank. The proposed method uses computational simulations of the electromagnetic waves generatedby PD, and obtains the time delay of the signal between each point in the 3D space and the UHFsensors. The calculated signals can be compared with the signals measured in the field, so thatthe position of the PD source can be located based on the best correlation between the simulatedpropagation delay and the measured data. The equations used in the proposed method are definedas 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. Thesolutions were sufficient to identify not only the occurrence of defects, but also the winding and theregion (top, centre or base) in which the defect occurred. In all cases, an accuracy of greater than15 cm was obtained for the location, in a 180 MVA three-phase transformer.
RESUMO
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.