Nueva metodología de la medida de descargas parciales en cables de alta tensión. Desarrollo de un sensor capacitivo de gran ancho de banda

En la actualidad la medida de descargas parciales constituye una herramiento eficaz para el diagnóstico de fallos de aislamiento. La presente tesis está centrada en los diferentes métodos de ensayo de descargas parciales en cables de media y alta tensión. Principalmente se ha estudiado la influencia de los diferentes métodos de ensayo en la evaluación de la carga de los pulsos de descargas parciales en ensayos off-line (ensayos en lso que se saca el cable fuera de servicio). La tesis analiza las particularidades de los métodos convencionales, y de los nuevos métodos o métodos no convencionales. Los métodos convencionales, empleados desde los años 60 en laboratorios de alta tensión, emplean filtros paso-banda como herramienta para la evaluación de los pulsos de descargas parciales. Los métodos no convencionales emplean sensores con anchos de banda muy superiores a los métodos convencionales pues esto permite la localización de los pulsos por técnicas de reflectometría y el uso de herramientas matemáticas que ayudan a la identificación de los pulsos de descargas parciales. En esta tesis se proponen y comparan diferentes métodos de evaluación de carga para los métodos no convencionales, y se establecen los límites de la incertidumbre en dichas medidas en función del ancho de banda de los sensores y de la longitud de los pulsos de descargas parciales. La tesis aborda el análisis de los transformadores de corriente de alta frecuencia que comúnmente se emplean como sensores de descargas parciales para medidas acopladas por campo magnético, y el estudio de los sensores acoplados por campo eléctrico. La comparativa de ambos sensores permite extraer conclusiones acerca de los anchos de banda obtenidos, de la incertidumbre alcanzada para diferentes longitudes de pulso y métodos de evaluación de carga, y de la sensibilidad de los sistemas de medida que emplean estos sensores. Las medidas experimentales se han realizado empleando diferentes prototipos de sensores acoplados porRodrigo Mor, A. (2012). Nueva metodología de la medida de descargas parciales en cables de alta tensión. Desarrollo de un sensor capacitivo de gran ancho de banda [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/16271Palanci

Design and Characterization of a Magnetic Loop Antenna for Partial Discharge Measurements in Gas Insulated Substations

© 2021 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] A recent investigation explored a new measuring concept used in partial discharges (PD) measurements in gas insulated substations (GIS), consisting of a magnetic loop antenna. The sensor¿s frequency response was characterized up to some tens of MHz. This paper proposes an improved version of the sensor with an extended bandwidth (BW) one order of magnitude higher: a resonance, attributed to a common mode current in the mounting hole, is identified and eliminated employing ferrite beads in the feeder cables. Moreover, this publication proposes an electric circuit model that fully covers the transverse electromagnetic mode (TEM) frequency range in GIS. The electric model is compared against experimental measurements using a 1 GHz bandwidth testbench, giving accurate results. Two contributions are achieved in this research: an improved magnetic loop antenna with extended bandwidth and an accurate electric circuit model. This publication paves the way for further research on time resolution and signal postprocessing techniques for magnetic loop antennas in GIS.Mier Escurra, C.; Rodrigo Mor, A.; Vaessen, P. (2021). Design and Characterization of a Magnetic Loop Antenna for Partial Discharge Measurements in Gas Insulated Substations. IEEE Sensors Journal. 21(17):18618-18625. https://doi.org/10.1109/JSEN.2021.3089084S1861818625211

PEA Electromagnetic Distortion Reduction by Impedance Grounding and Pulsed Voltage Electrode Configurations

[EN] Space charges are one of the main challenges facing the constantly increasing use of extruded high voltage direct current (HVDC) cables. The Pulsed Electro-Acoustic (PEA) method is one of the most common procedures for space charge measurements of insulation. One issue with the PEA method is distortion due to the crosstalk between the applied voltage pulse and the acoustic sensor. This work analyzed two factors involved in the reduction in this distortion: the influence of the exposed semiconductor distance between the injection electrodes and PEA test cell, and the influence of adding a reactance at the grounding circuit of the PEA test cell. The interaction of these two factors with the distortion was analyzed through a series of experimental testing. Moreover, the performance regarding distortion after applying a developed coaxial injection was compared with the standard non-coaxial injection configuration. It was observed that these two factors had a direct impact on distortion and can be utilized for the reduction in distortion arising from the crosstalk of the applied pulsed voltage. The results can be utilized for the consideration of practical aspects during the construction of a PEA test setup for the measurement of full-size HVDC cables.This research was funded by Delt University of Technology.Mier Escurra, G.; Rodrigo Mor, A.; Castro, LC.; Vaessen, P. (2021). PEA Electromagnetic Distortion Reduction by Impedance Grounding and Pulsed Voltage Electrode Configurations. Sensors. 21(17):1-12. https://doi.org/10.3390/s21175837S112211

MÉTRICAS E DESEMPENHO: A PERCEPÇÃO DE GESTORES E PROFISSIONAIS DE MARKETING

Esse trabalho estuda a relação entre o uso de métricas de gestão de marketing e os resultados obtidos pelas ações nessa área, na percepção de seus gestores e executivos. Foram levantadas junto à literatura sobre prestação de contas em marketing (marketing accountability) e de gestão, diversas métricas que neste artigo foram divididas em métricas de marketing, financeiras e de gestão. Profissionais da área responderam questionário que buscou identificar qual é o grau de utilização dessas métricas e a influência de seu uso sobre o resultado percebido nas ações de marketing. Os dados encontrados sugerem uma contradição, pois, embora os gestores em geral afirmem usar algum tipo de métrica, os resultados da análise estatística não apontaram relação significativa entre esse uso e o desempenho percebido pelos mesmos gestores. Esses resultados corroboram grande parte dos trabalhos na área que apontam haver necessidade de utilização de métricas que comprovem os resultados obtidos pelas organizações em suas ações de marketing. A partir dos dados levantados é possível supor que os gestores levam em conta as métricas em suas ações de marketing no momento de formulação dessas ações. Entretanto, não as utilizam no decorrer ou após a execução de tais ações. A quantidade reduzida de indivíduos da amostra, dada certa dificuldade de contato e participação de gestores de marketing em pesquisas dessa natureza, traz algumas limitações ao estudo, dificuldade também encontrada por trabalhos anteriores na mesma área. O marketing poderia aumentar suas contribuições às organizações, caso a mensuração de seus resultados sejam compreendidas e disseminadas

Long Term Partial Discharge Behavior of Protrusion Defect in HVDC GIS

2022 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] This article investigates the partial discharge (PD) behavior of protrusion defects in real-size high-voltage direct current gas insulated switchgear (HVDC GIS) for SF6 and SF6 alternative gases including fluoronitrile-CO2 mixture (10%) and fluoroketone-dry air mixture (6.6%). The evolution of PD apparent charge and PD repetition rate for all investigated gases is presented and discussed. The measurement results indicate that PD behavior changes as a function of time. The PD apparent charge increases and the PD repetition rate decreases with the increase of voltage application time. This evolution can be related to the change in protrusion tip radius due to electrochemical etching: radius of the protrusion's tip being enlarged. In addition, the pulse sequence analysis (PSA) plots of the PDs caused by this defect are presented. It is observed that the PSA plots change over time. Therefore, for the development of a robust PD monitoring and defect-recognition tool, as well as for the assessment of risks in the operation of HVDC GIS, it is crucial to take these changes into account.This work was supported in part by the Horizon 2020 Progress on Meshed HVDC Offshore Transmission Networks (PROMOTioN) Project under Grant 691714 and in part by the French Government through the frame of "Investissements d'avenir," under Grant ANE-ITE-002-01.Vu, C.; Toigo, C.; Jacquier, F.; Girodet, A.; Riechert, U.; Tuczek, MN.; Rodrigo Mor, A. (2022). Long Term Partial Discharge Behavior of Protrusion Defect in HVDC GIS. IEEE Transactions on Dielectrics and Electrical Insulation. 29(6):2294-2302. https://doi.org/10.1109/TDEI.2022.32067262294230229

Identification of Partial Discharge Through Cable-Specific Adaption and Neural Network Ensemble

[EN] This paper proposes to administer a multi-step artificial intelligence approach with an ensemble of adaptive neural networks (NNs) trained on 50000 samples to identify partial discharge (PD) diagnostic measurements for in-service medium voltage (MV) power cables. To evaluate the performance of the algorithm, a case study was performed on cables deliberately selected to contain both uncomplicated measurements and disruptive irregularities representative of conditions during field testing. The experimental test results prove that the proposed cable-specific adaptation improves PD identification accuracy, with further increment through the NN ensembles. The main contribution of the approach is in both the cable-specific adaption and the NN ensemble being applied to MV cable field measurements.Yeo, J.; Jin, H.; Rodrigo Mor, A.; Yuen, C.; Tushar, W.; Saha, TK.; Seng Ng, C. (2021). Identification of Partial Discharge Through Cable-Specific Adaption and Neural Network Ensemble. IEEE Transactions on Power Delivery. 1-10. https://doi.org/10.1109/TPWRD.2021.3093670S11

Diagnóstico del aislamiento principal de bobinas estatóricas sometidas a esfuerzos termoeléctricos en laboratorio

El estudio de los mecanismos de degradación del sistema de aislamiento del estator de máquinas eléctricas de alto voltaje es la base fundamental para la propuesta, validación y aplicación de criterios de diagnóstico en campo. A nivel mundial la principal herramienta para la reproducción controlada de los mecanismos de degradación del aislamiento ha sido la implementación de programas de envejecimiento acelerado. En estos, se someten bobinas de prueba a esfuerzos tipo TEAM (térmicos, eléctricos, ambientales y mecánicos) y por medio de técnicas de medición se estiman las probables causas que llevaron a la obtención de los resultados de las mediciones. Por décadas, los centros de investigación han aplicado esta metodología lo cual ha llevado al establecimiento de los criterios de diagnóstico hoy empleados en campo. Esta investigación doctoral contribuyó al estado del arte con el desarrollo de un nuevo índice para evaluación de la degradación del aislamiento que permitió relacionar las pruebas de capacitancia/factor de disipación y descargas parciales, cuyos resultados predominantemente se han interpretado de forma independiente. Así mismo, la investigación aplicó técnicas de medición no convencionales, como el análisis fisicoquímico, buscando complementar la información de diagnóstico que se puede extraer con las técnicas convencionales: mediciones dieléctricas

Metrological Qualification of PD Analysers for Insulation Diagnosis of HVDC and HVAC Grids

On-site partial discharge (PD) measurements have turned out to be a very efficient technique for determining the insulation condition in high-voltage electrical grids (AIS, cable systems, GIS, HVDC converters, etc.); however, there is not any standardised procedure for determining the performances of PD measuring systems. In on-line and on-site PD measurements, high-frequency current transformers (HFCTs) are commonly used as sensors as they allow for monitoring over long distances in high-voltage installations. To ensure the required performances, a metrological qualification of the PD analysers by applying an evaluation procedure is necessary. A novel evaluation procedure was established to specify the quantities to be measured (electrical charge and PD repetition rate) and to describe the evaluation tests considering the measured influence parameters: noise, charge amplitude, pulse width and time interval between consecutive pulses. This procedure was applied to different types of PD analysers used for off-line measurements, sporadic on-line measurements and continuous PD monitoring. The procedure was validated in a round-robin test involving two metrological institutes (RISE from Sweden and FFII from Spain) and three universities (TUDelft from the Netherlands, TAU from Finland and UPM from Spain). With this round-robin test, the effectiveness of the proposed qualification procedure for discriminating between efficient and inappropriate PD analysers was demonstrated. Furthermore, it was shown that the PD charge quantity can be properly determined for on-line measurements and continuous monitoring by integrating the pulse signals acquired with HFCT sensors. In this case, these sensors must have a flat frequency spectrum in the range between several tens of kHz and at least two tens of MHz, where the frequency pulse content is more significant. The proposed qualification procedure can be useful for improving the future versions of the technical specification TS IEC 62478 and the standard IEC 60270.Peer reviewe

Diagnosis, Prognosis and Treatment of Canine Cutaneous and Subcutaneous Mast Cell Tumors

Mast cell tumors (MCTs) are hematopoietic neoplasms composed of mast cells. It is highly common in dogs and is extremely important in the veterinary oncology field. It represents the third most common tumor subtype, and is the most common malignant skin tumor in dogs, corresponding to 11% of skin cancer cases. The objective of this critical review was to present the report of the 2nd Consensus meeting on the Diagnosis, Prognosis, and Treatment of Canine Cutaneous and Subcutaneous Mast Cell Tumors, which was organized by the Brazilian Association of Veterinary Oncology (ABROVET) in August 2021. The most recent information on cutaneous and subcutaneous mast cell tumors in dogs is presented and discussed