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JOSÉ MANUEL FRESNO   Mr.  Other 
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JOSÉ MANUEL FRESNO published an article in November 2017.
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G. Robles

51 shared publications

Department of Electrical Engineering, Universidad Carlos III de Madrid, Avda. Universidad, 30, Leganés, Madrid 28911, Spain; s

5
Publications
38
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7
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17
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Distribution of Articles published per year 
(2015 - 2017)
Total number of journals
published in
 
3
 
Publications
CONFERENCE-ARTICLE 18 Reads 1 Citation Planar localization of radio-frequency or acoustic sources with two receivers José Manuel Fresno, Guillermo Robles, Juan Manuel Martínez-T... Published: 14 November 2017
Proceedings, doi: 10.3390/ecsa-4-04892
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In the localization of electromagnetic or acoustic emitters, generally, when a pulse is radiated from a source, the wave will arrive to two receivers at different times. One of the advantages of measuring these time differences of arrival or TDOA is that it is not required a common clock as in other localization techniques based on the time of arrival of the pulse to the receiver. With only two sensors, all the possible points in the plane that would give the same TDOA describe a hyperbola. Using an independent third receiver and calculating the intersection of the three hyperbolas will give the position of the source. Therefore, planar localization of emitters using multilateration techniques can be solved at least with three receivers. This paper presents a method to locate sources in a plane with only two receivers reducing the number of acquisition channels and hence, the cost of the equipment. One of the receivers is in a fixed position and the other describes a circumference around the first one. The TDOA are measured at different angles completing a total turn and obtaining a periodic function, angle versus TDOA, that has all the geometric information needed to locate the source. The paper will show how to derive this function analytically with the distance from the fixed receiver to the source and a bearing angle as parameters. Then, it will be demonstrated that it is possible to fit the curve with experimental measurements to obtain the parameters of the position of the source.

CONFERENCE-ARTICLE 5 Reads 0 Citations <span>The influence of antenna positioning errors on the radio-frequency localization of partial discharges sources</spa... José Manuel Fresno, Guillermo Robles, Brian Stewart, Juan Ma... Published: 14 November 2016
Proceedings, doi: 10.3390/ecsa-3-E003
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Electrical insulation can have imperfections due to manufacturing or ageing. When the insulation is electrically stressed, discharges may happen in these inhomogeneous imperfect locations resulting in partial discharge (PD) which have very fast rise times and short time durations. Since charges are accelerated within PD activity, radiated electromagnetic energy across a wide bandwidth of frequencies can occur. The measurement of the radiated PD energy is widely employed to identify defective insulation within high voltage equipment. Based on assessment of the strength and nature of the emitted PD signals, determination is made to carry out predictive maintenance in order to prevent equipment breakdown. The location of emitted radiated PD signals may be determined using multi-lateration techniques using an array of at least 4 antennas. Depending on the relative position between the antennas and the PD source, the radiated emissions from the PD source arrive at each antenna at different times. The relative time differences of arrivals (TDOA) together with the antennas position are variables used to locate the PD source in 3D space. The effect on the location error of a PD source using TDOA calculations based on acquisition sample time errors is a topic which has previously been studied (see bibliography). This paper now investigates the accuracy on PD location as a consequence of error on the measured positions of the antennas. This paper evaluates the influence of positional antenna error on the possible accuracy of the localization of the PD source. This error is analyzed for 3 different antenna array layouts and for different vector directions from the arrays. Additionally, the least sensitive layout with regard to positioning errors is proposed to assist in improving the location accuracy of PD sources.

Article 4 Reads 5 Citations Antenna Deployment for the Localization of Partial Discharges in Open-Air Substations Guillermo Robles, José Manuel Fresno, Matilde Sánchez-Fernán... Published: 15 April 2016
Sensors, doi: 10.3390/s16040541
DOI See at publisher website PubMed View at PubMed ABS Show/hide abstract
Partial discharges are ionization processes inside or on the surface of dielectrics that can unveil insulation problems in electrical equipment. The charge accumulated is released under certain environmental and voltage conditions attacking the insulation both physically and chemically. The final consequence of a continuous occurrence of these events is the breakdown of the dielectric. The electron avalanche provokes a derivative of the electric field with respect to time, creating an electromagnetic impulse that can be detected with antennas. The localization of the source helps in the identification of the piece of equipment that has to be decommissioned. This can be done by deploying antennas and calculating the time difference of arrival (TDOA) of the electromagnetic pulses. However, small errors in this parameter can lead to great displacements of the calculated position of the source. Usually, four antennas are used to find the source but the array geometry has to be correctly deployed to have minimal errors in the localization. This paper demonstrates, by an analysis based on simulation and also experimentally, that the most common layouts are not always the best options and proposes a simple antenna layout to reduce the systematic error in the TDOA calculation due to the positions of the antennas in the array.
CONFERENCE-ARTICLE 7 Reads 1 Citation Antenna array layout for the localization of partial discharges in open-air substations Guillermo Robles, José Manuel Fresno, Matilde Sánchez-Fernán... Published: 10 November 2015
2nd International Electronic Conference on Sensors and Applications, doi: 10.3390/ecsa-2-E008
DOI See at publisher website ABS Show/hide abstract

Partial discharges are ionization processes inside or on the surface of dielectrics that can unveil insulation problems in electrical equipment. The charge accumulated in the dielectric is released under certain environmental and voltage conditions attacking the insulation both physically and chemically. The final consequence of a continuous occurrence of these events is the breakdown of the dielectric. The electron avalanche provokes a derivative of the electric field close to the damaged insulation creating an electromagnetic impulse that can be detected with antennas. The localization of the source of partial discharges helps in the identification of the piece of equipment that has to be decommissioned. This can be done deploying antennas in open-air substations and calculating the time difference of arrival (TDOA) of the electromagnetic pulses. This parameter is critical in the localization and small errors can lead to a great displacement of the calculated position of the source. Usually, four antennas are used to find the source in space but the array has to be correctly deployed to have minimal errors in the localization. This paper demonstrates theoretically and experimentally that the most common layouts are not the best option and proposes a simple antenna layout to reduce the systematic error in the TDOA calculation due to the positions of the antennas.

Article 4 Reads 14 Citations Separation of Radio-Frequency Sources and Localization of Partial Discharges in Noisy Environments Guillermo Robles, José Fresno, Juan Martinez-Tarifa Published: 27 April 2015
Sensors, doi: 10.3390/s150509882
DOI See at publisher website PubMed View at PubMed ABS Show/hide abstract
The detection of partial discharges (PD) can help in early-warning detection systems to protect critical assets in power systems. The radio-frequency emission of these events can be measured with antennas even when the equipment is in service which reduces dramatically the maintenance costs and favours the implementation of condition-based monitoring systems. The drawback of these type of measurements is the difficulty of having a reference signal to study the events in a classical phase-resolved partial discharge pattern (PRPD). Therefore, in open-air substations and overhead lines where interferences from radio and TV broadcasting and mobile communications are important sources of noise and other pulsed interferences from rectifiers or inverters can be present, it is difficult to identify whether there is partial discharges activity or not. This paper proposes a robust method to separate the events captured with the antennas, identify which of them are partial discharges and localize the piece of equipment that is having problems. The separation is done with power ratio (PR) maps based on the spectral characteristics of the signal and the identification of the type of event is done localizing the source with an array of four antennas. Several classical methods to calculate the time differences of arrival (TDOA) of the emission to the antennas have been tested, and the localization is done using particle swarm optimization (PSO) to minimize a distance function.
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