Open Access
Structural health monitoring of solar trackers using distributed fiber optic sensors
(SPIE, 2019) Mariñelarena Ollacarizqueta, Jon; Mompó Roselló, Juan José; Zurita Gabasa, Jesús; Urricelqui Polvorinos, Javier; Júdez Colorado, Aitor; López-Amo Sáinz, Manuel; Jiménez Romero, Sergio; Achaerandio, Álvaro; Loayssa Lara, Alayn; Institute of Smart Cities - ISC; Gobierno de Navarra / Nafarroako Gobernua, 0011-1365-2017-000122; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We demonstrate the application of a novel type of distributed fiber optic sensors (DFOSs) to dynamically monitor the effects of wind on solar tracker structures used in photovoltaic power stations. This DFOS is based on the stimulated Brillouin scattering nonlinear optical effect in optical fiber, which can be used to measure the distribution of strain and temperature along a given structure. However, contrary to existing solutions, the sensor provides dynamic real-time measurements with hundreds or even thousands of full simultaneous measurements for all positions in the fiber each second. Moreover, high-precision and high spatial resolution are obtained. This so-called dynamic Brillouin optical time-domain analysis (D-BOTDA) sensor provides real-time monitoring of the bending and torsion of the structure of solar trackers in response to wind load. This helps the solar tracker manufacturer asses and improve the mechanical designs so as to introduce corrective measures and develop cost-effective components that properly withstand the effects of wind at any given location. We experimentally demonstrate the application of a D-BOTDA sensing system to measure distributed bending and, for the first time to our knowledge, also distributed torsion along the stressed beam of the solar tracker. For this purpose, we have developed a procedure to instrument the torsion beam with two optical sensing fibers that are fixed helically wound along the beam in opposite directions, so that any common-mode thermal or bending effects are removed. We initially performed tests in a laboratory facility in which sections of the torsion beam could be subjected to controlled moments. Static and dynamic loads were applied and the measured deformations were compared to those obtained with fiber Bragg gratings, which just provide point measurements of strain. In both cases, full agreement was demonstrated. Finally, the system was installed in an operational solar park.
Open Access
Egituren egoeraren monitorizaziorako zuntz optikoan oinarritutako sentsore sinplifikatua
(Udako Euskal Unibertsitatea, 2015) Iribas Pardo, Haritz; Sagüés García, Mikel; Mariñelarena Ollacarizqueta, Jon; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Brillouin hedatuko denbora eremu optikoaren analisian (BOTDA) oinarritutako sentsoreak, estruktura handien (100 km luzerako estrukturak) deformazioa eta tenperatura neurtzeko gaitasuna dute. Lan honetan, BOTDA konfigurazio sinplifikatua aurkezten dugu. Erabilitako konfigurazioaren helburua sentsorearen prezioa murriztea da, detekzio prozesuan parte hartzen duten seinale optikoen sortze prozesua sinplifikatuz. Proposatutako teknika hau, iturri optiko bati irrati-maiztasun (IM) pultsu modulatu bat aplikatuz sortutako osagai espektralen iragazketa optiko pasiboan oinarritzen da. Laborategiko esperimentuek frogatzen dute tenperatura hedatuko neurriak 1,1 metroko erresoluzioarekin 5 km zuntz optikoan zehar
Open Access
Detrimental effects in Brillouin distributed sensors caused by EDFA transient
(Optical Society of America, 2017) Feng, Cheng; Iribas Pardo, Haritz; Mariñelarena Ollacarizqueta, Jon; Schneider, Thomas; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
We investigate the deleterious effect and the error in Brillouin optical time-domain analyzers induced by the combination of a low extinction ratio pulse generation with the transient behavior of erbium-doped fiber amplifiers.
Open Access
In-field torsion measurements on solar trackers using fiber optic sensors
(Optica, 2020) Leandro González, Daniel; Bravo Acha, Mikel; Júdez Colorado, Aitor; Mariñelarena Ollacarizqueta, Jon; Falcone Lanas, Francisco; Loayssa Lara, Alayn; López-Amo Sáinz, Manuel; Jiménez, S.; Achaerandio, Álvaro; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Gobierno de Navarra / Nafarroako Gobernua
In-field torsion measurements on solar trackers using fiber Bragg gratings are presented. 45 FBG sensors have been deployed in an operational solar energy plant to study the mechanical response of the structure to wind.
Open Access
Fiber-optic brillouin distributed sensors: from dynamic to long-range measurements
(CRC Press, 2018) Loayssa Lara, Alayn; Urricelqui Polvorinos, Javier; Iribas Pardo, Haritz; Mompó Roselló, Juan José; Mariñelarena Ollacarizqueta, Jon; Estadística, Informática y Matemáticas; Ingeniería Eléctrica, Electrónica y de Comunicación; Estatistika, Informatika eta Matematika; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This chapter focuses on Brillouin optical time-domain analysis (BOTDA) sensors because they are the most successful Brillouin distributed sensors (BDS) type in terms of performance and practical applications. Distributed sensor featuring can be done in the time, coherence, or frequency domains, giving rise to the three main analysis BDS types: BOTDA, Brillouin optical correlation-domain analysis (BOCDA), and Brillouin optical frequency-domain analysis (BOFDA). The distance range of measurements performed using a BOTDA sensor is given by the length of sensing fiber that the system is able to measure with a specified performance in terms of measurement precision and time. The chapter reviews the fundamentals and the research directions in BDSs. The applications of the technology are multiple and in diverse fields¿for instance, in the oil and gas industry, where BDSs have been applied to measure temperature and strain along the umbilical cables used for subsea wells.
Open Access
Non-local effects in Brillouin optical time-domain analysis sensors
(MDPI, 2017) Iribas Pardo, Haritz; Urricelqui Polvorinos, Javier; Mompó Roselló, Juan José; Mariñelarena Ollacarizqueta, Jon; Loayssa Lara, Alayn; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Brillouin optical time-domain analysis (BOTDA) sensors have great potential to provide distributed measurements of temperature and strain over large structures with high spatial resolution and measurement precision. However, their performance ultimately depends on the amount of probe and pump pulse power that can be injected into the sensing fiber, which determines the signal-to-noise ratio of the detected measurement signal. The probe wave power is constrained by the generation of noise induced by spontaneous Brillouin scattering and at lower power by the so-called non-local effects. In this work, we focus on the latter. We review the physical origins of non-local effects and analyze the performance impairments that they bring. In addition, we discuss the different methods that have been proposed to counteract these effects comparing their relative merits and ultimate performance. Particularly, we focus on a technique that we have devised to compensate non-local effects which is based on introducing an optical frequency modulation or dithering to the probe wave. This method is shown to provide a comprehensive solution to most of the impairments associated with non-local effects and also to enable some side benefits, such as amplification of the pump pulses to compensate the attenuation of the fiber.
Open Access
Enhancement of the dynamic range in slope-assisted coherent brillouin optical time-domain analysis sensors
(IEEE, 2017) Mariñelarena Ollacarizqueta, Jon; Urricelqui Polvorinos, Javier; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We present two techniques that provide an extension of the dynamic range of coherent Brillouin optical time-domain analysis (BOTDA) sensors for dynamic measurements. This type of BOTDA sensors rely on self-heterodyne detection of a phase-modulated probe wave and the dynamic range for fast measurements is limited to the linear region of the RF phase-shift spectrum measured. The first method for range extension that we introduce is based on launching pump pulses containing multiple frequency components. This makes the Brillouin spectra generated by each component to overlap, providing a wider linear region of the detected RF phase-shift spectrum and allowing to measure larger Brillouin frequency shift variations. The second method relies on shortening the length of the pump pulses, which leads to the broadening of the detected RF spectra. The theoretical fundamentals of both range enhancing techniques are presented. Moreover, we experimentally demonstrate that they provide a threefold to fourfold enhancement in the dynamic range. Finally, the factors limiting their performance are determined: for the multi-frequency pump pulse technique, it is the worsening of Kerr non-linear effects due to the simultaneous propagation of multiple spectral components in the fiber, and, for the pulse-shortening method, it is the signal-to-noise ratio penalty linked to the reduction of the magnitude of the Brillouin interaction.
Open Access
Pulse coding linearization for Brillouin optical time-domain analysis sensors
(Optical Society of America, 2018) Mariñelarena Ollacarizqueta, Jon; Iribas Pardo, Haritz; Loayssa Lara, Alayn; Institute of Smart Cities - ISC
We introduce a simple method to extend the performance of pulse coding techniques in their application to Brillouin optical time-domain analysis sensors (BOTDA). It is based on applying a simple logarithmic processing on the detected probe wave that compensates the deviation from linearity of the sensor response for long code lengths. The technique ensures that the accumulated effect of a sequence of pulses is equal to the linear addition of the effects of the individual components, which is the essential condition to ensure a correct decoding of the probe gain measurement. We experimentally demonstrate the compensation of the Brillouin frequency shift error induced by the accumulated gain nonlinearity. Furthermore, a proof-of-concept 80 km sensing link within a total 200 km fiber loop demonstrated a better than 2 MHz precision with 2 m spatial resolution.
Open Access
Investigation on the working point of slope-assisted dynamic Brillouin distributed fiber sensing
(SPIE, 2019) Feng, Cheng; Mariñelarena Ollacarizqueta, Jon; Schneider, Thomas; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In this paper, an investigation on the working point of slope-assisted dynamic distributed Brillouin sensing is presented. A comparison has been carried out between the sensing performances achieved at the inflection point and the 3 dB point of the Brillouin gain spectrum. Besides the intrinsic 13.1% frequency-to-amplitude sensitivity enhancement and a higher signal level, the dynamic sensing at the inflection point can achieve a doubled in maximum and in average a 36.8% wider dynamic range with much better working point symmetry. Simulations with strain signals also demonstrate that, compared to the 3 dB point, the average error at the inflection point can be significantly reduced to only 27.7%. As shown in this work, by a simple shift of the working point from the 3 dB to the inflection point, slope-assisted dynamic sensing can be well enhanced.
Open Access
Zuntz optikoan oinarritutako sentsoreen prestazioen muga-efektu berria, egituren egoera monitorizatzea helburu
(Udako Euskal Unibertsitatea, 2017) Iribas Pardo, Haritz; Mariñelarena Ollacarizqueta, Jon; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Brillouin denbora-eremu optikoaren analisian (BOTDA) oinarritutako sentsoreak estruktura handien (120 km luzerako estrukturak) deformazioa eta tenperatura neurtzeko gaitasuna dute, metro bateko bereizmen espazialarekin. Lan honetan, sentsorearen merkatu-prezioa handitu gabe bereizmen espazial txikiagoa lortzeko beharrezkoa litzatekeen teknika erabiltzeak dituen efektu kaltegarriak aztertu egin dira. Izan ere, pultsu azkar bat sortzeko beharrezkoak diren Mach-Zehnder modulagailu elektrooptikoek iraungitze-ratio (ER) txikia dute. Horiek horrela, aztertu egin da pultsatutako seinalea sortzeko sorgailuak duen ERaren eragina BOTDA sentsoreen prestazioetan, akats handiak sortzen direla ondorioztatuz.