Robles G., Febbo M., Machado S.P., García B. (2020) Piezoelectric Energy Harvesting System to Detect Winding Deformation in Power Transformers. In: Ball A., Gelman L., Rao B. (eds) Advances in Asset Management and Condition Monitoring. Smart Innovation, Systems and Technologies, vol 166. Springer, Cham.
Open Access available at https://link.springer.com/content/pdf/10.1007%2F978-3-030-57745-2.pdf
Abstract – One common use of energy harvesting systems is the installation on applications where the access to conventional sources of energy is difficult due to availability, space constraints, environmental hazards or sealed equipment. In this work, we propose an alternative use of an energy harvesting system based on a piezoelectric that takes the vibration of a transformer tank due to winding deformations and hence helps to monitor the condition of the equipment. The system consists on a cantilever piezoelectric beam with a mass tuned to the resonant frequency of the vibration. The output of the piezoelectric is connected to a quadrupler, a low-drop regulator and a capacitive storage. The harvested voltage is planned to supply a low power microprocessor that detects changes in the vibration measurements to determine an abnormal behavior of the transformer. This work introduces the causes of abnormal vibration of transformers, describes the installation of the piezoelectric on a model that generates the same acceleration as the vibration of a transformer tank and studies the capability of charging capacitors to determine the feasibility of the method.
Keywords – Condition monitoring, Energy harvesting, Piezoelectrics, Power transformers, Vibration analysis
Muhammad Shafiq, Guillermo Robles, Amjad Hussain, Kimmo Kauhaniemi, Matti Lehtonen, Identification and Location of Partial Discharge Defects in Medium Voltage AC Cables. 5 August 2019. Proceedings of the 26th Nordic Insulation Symposium NORD-IS, Trondheim (Norway), pp 22-27. ISSN 2535-3969.
Open access available athttps://doi.org/10.5324/nordis.v0i26.3269
Abstract – The presence of partial discharge (PD) in electrical equipment is the confirmation or indication of an ongoing degradation of its dielectric insulation. PD study is a widely used tool for condition monitoring of medium voltage (MV) cables. The location of the defects can be considered as one of the most important tasks of diagnosis in underground installations of MV cables. A lot of references can be found on the location of single PD sources along the cable. However, several PD defects can be active simultaneously along a cable section. This paper presents an experimental study on a MV cable having two PD sources and noise. Adopting one end measurement technique, a high frequency current transformer (HFCT) is used to capture the PD current pulses. A simple approach of identification of the PD signals originated from different PD sources is presented based on wave-shape study along with a time domain reflectometry analysis. The presented measurement methodology and time domain analysis technique provides a convenient way for detection and location of more than one PD sources along a cable section.
M. G. De La Calle, J. M. Martínez-Tarifa, Á. M. Gómez Solanilla and G. Robles, “Uncertainty Sources in the Estimation of the Partial Discharge Inception Voltage in Turn-to-Turn Insulation Systems,” in IEEE Access, vol. 8, pp. 157510-157519, 24 August 2020.
Electronic ISSN: 2169-3536
Abstract — Partial discharges (PD) are one of the main causes of premature failure in low-voltage motors driven by variable-speed drives. The use of these control systems are being quite extended due to new applications, such as the more electric aircraft (MEA) or hybrid and electric vehicles, and this has pushed research towards appropriate designs of electric motors to avoid, as much as possible, the presence of PD within their windings. This article presents a model to predict the partial discharge inception voltage (PDIV) in the insulation of low-voltage machines. A value for the secondary ionization coefficient based on a statistical study is also proposed. The deviations of the model are also studied by obtaining the uncertainty of the value of that coeficient and the predicted values of the PDIV for a set of wires. This uncertainty will be compared with other error sources such as generator harmonics and humidity. Finally, the tests are done for different temperatures extend the model applicability.
Keywords — Insulation design, inverter-fed machine, partial discharges, Paschen’s law, temperature, Townsend’s coefficients.