A methodology for performance and compatibility evaluation of an all-digital substation protection system

A power system protection system consists, at least, of an instrument trans- former, a protective device (relay), and a circuit breaker. Conventional instrument transformers bring currents and voltages from power network levels to much lower scaled-down replicas that serve as input signals to protective relays. The relay's function is to measure input signals (or a relationship among them in some cases) and compare them to defined operating characteristic thresholds (relay settings) to quickly decide whether to operate associated circuit breaker(s). Existing protection systems within a substation are based on a hardwired interface between instrument transformers and protective relays. Recent development of electronic instrument transformers and the spread of digital relays allow the development of an all-digital protection system, in which the traditional analog interface has been replaced with a digital signal connected to digital relays through a digital communication link (process bus). Due to their design, conventional instrument transformers introduce distortions to the current and voltage signal replicas. These distortions may cause protective relays to misoperate. On the other hand, non-conventional instrument transformers promise distortion-free replicas, which, in turn, should translate into better relay performance. Replacing hardwired signals with a communication bus also reduces the significant cost associated with copper wiring. An all-digital system should provide compatibility and interoperability so that different electronic instrument transformers can be connected to different digital relays (under a multi-vendor connection) Since the novel all-digital system has never been implemented and/or tested in practice so far, its superior performance needs to be evaluated. This thesis proposes a methodology for performance and compatibility evaluation of an all-digital protection system through application testing. The approach defines the performance indices and compatibility indices as well as the evaluation methodology

Bridges Structural Health Monitoring and Deterioration Detection Synthesis of Knowledge and Technology

INE/AUTC 10.0

Optoelectronic sensors based on molecularly imprinted polymers

La ricerca è stata incentrata sullo sviluppo di sensori ottici (senza impiego di indicatori) basati su fibre ottiche plastiche (POF). Queste presentano caratteristiche vantaggiose come flessibilità, grande apertura numerica e facile lavorazione; essendo inoltre in grado di sopportare curvature più strette rispetto alle fibre di vetro. Pertanto, le POF risultano adatte alla realizzazione di sensori ottici ad alta sensibilità, miniaturizzati, robusti ed a basso costo. Due approcci differenti sono stati impiegati: il primo è stato basato sullo sviluppo dei sensori direttamente sulle fibre ottiche plastiche (POF) (sensori intrinseci) e il secondo prevede l'impiego di diverse guide d'onda ad esempio in PMMA o PET (sensori estrinseci). I due approcci mostrano caratteristiche distinte per la facile preparazione e sono stati studiati al fine di ottenere una migliore riproducibilità. I sensori sfruttano diversi fenomeni ottici: la risonanza plasmonica di superficie (SPR) o l'accoppiamento di onde evanescenti (EWC). Tutti i sensori impiegano recettori biomimetici sintetici, cioè polimeri a stampo molecolare (MIP) per il rilevamento di analiti in matrici complesse acquose o organiche. I bio-recettori comunemente usati, nonostante la loro elevata selettività e sensibilità, soffrono di grossi svantaggi quali la non disponibilità per tutti i substrati, il limite di analisi in condizioni biologiche e la costosa e lunga procedura per il loro utilizzo. Invece i MIP risultano più resistenti, anche in condizioni di analisi più drastiche (elevate T, bassi pH,…), pur mantenendo affinità e selettività elevate, pari a quelle dei bio-recettori. Tali caratteristiche rendendo questi recettori sintetici utili ai fini sensoristici. Sono stati sviluppati MIP specifici, basati su monomeri funzionali che impiegano interazioni non covalenti con comune composizione riguardo il monomero funzionale e il cross-linker. In alcuni casi, la composizione MIP è stata ottimizzata mediante metodi computazionali considerando diversi monomeri funzionali e cross-linker nonché possibili interazioni interferenti. Le caratteristiche dei MIP, come costante di affinità, capacità di assorbimento e selettività sono state valutate mediante procedura di equilibrazione batch e procedura a flusso. Differenti formulazioni di MIP in forma di particelle porose e sferiche sono state considerate. Sono stati sviluppati e caratterizzati MIP per l'analisi delle seguenti molecole: furaldeide (2-FAL) e dibenzildisolfuro (DBDS) data la loro importanza come utili indicatori dell'usura dei trasformatori di media tensione. La 2-FAL è stata considerata anche in matrici acquose, data la sua rilevanza nel controllo qualità degli alimenti. I sensori ottici sono stati caratterizzati determinando le isoterme di adsorbimento sullo strato polimerico, basato sulla risposta del sensore. I sensori SPR risultano promettenti grazie alla elevata sensibilità, al basso costo e alla possibilità di miniaturizzazione impiegando le POF. Inoltre, l'impiego di MIP come recettore garantiscono un'elevata selettività e costante di affinità (Kaff), un basso LOD e la possibilità del riutilizzo. Simili risultati sono stati ottenuti con sensori basati sull'accoppiamento di onde evanescenti (EWC) che tuttavia risultano più promettenti delle piattaforme SPR presentando il vantaggio dell'eliminazione dello strato di oro e quindi una migliore riproducibilità. Inoltre, nuovi materiali per l'imprinting molecolare sono stati considerati per migliorare la biocompatibilità. In particolare, la fibroina della seta è stata esaminata date le sue ottimali proprietà ottiche e meccaniche ed essendo un biomateriale già approvato per applicazioni biomediche. Risultati preliminari sull'imprinting di fibroina con glucosio sono stati promettenti; riscontrando un fattore di imprinting superiore a uno. Tale materiale stampato è facilmente ottenuto come strato sottile adatto allo sviluppo di sensori.The research was focused on the development of marker-free optical sensors based on plastic optical fibers (POF). These are particularly suitable for sensing application because of their exceptional flexibility, large numerical aperture, and easy manipulation. Also, they are able to withstand smaller bend radii than glass fibers. Therefore, POFs are suitable for the realization of low-cost and miniaturized optical sensors both robust and highly sensitive for application with a remote control. Two approaches have been exploited the first in which the optical platform was directly developed on plastic optical fibers (POF) (intrinsic sensors) and the second that employ different waveguides made for example of PMMA or PET (extrinsic sensors). The two approaches show distinct characteristics of easy preparation and have been investigated to obtain a better reproducibility. In both sensors, different optical phenomena have been exploited, in particular, surface plasmon resonance (SPR) and the evanescent wave coupling (EWC). All the sensors employ synthetic biomimetic receptors, i.e. molecularly imprinted polymers (MIPs) for the detection of analytes in complex aqueous or organic matrices. The most commonly used bio-receptors, despite their high selectivity and sensitivity, suffer from great disadvantages as not being available for all the substrate, being limited to the biological condition of analysis and requiring an expensive and time-consuming development procedure. Instead, MIPs are more resistant, even in harsh conditions of analysis, while maintaining the high affinity and selectivity of the biological receptors, so making these synthetic receptors really promising for sensing purposes. Some specific MIPs have been developed, based on non-covalent interactions template-functional monomers, and with the most common composition as far as the functional monomer and the cross-linker are concerned. In some cases, the MIP composition was optimized by computational methods considering different functional monomers and cross-linkers as well as possible interfering interactions. The MIPs characteristics, as the affinity constant, the capacity of uptake and selectivity have been evaluated by batch procedure and the flow procedure. Porous MIP particles and MIP beads have been considered and characterized by batch equilibration. In particular MIPs for sensing the following molecules have been developed and characterized: 2-FAL (2-furhaldehide) and dibenzyldisulfide (DBDS) because of their rising importance as useful markers of health status of the middle tension transformers in the large distribution energy. 2-FAL was considered in aqueous matrices too, in view of its relevance in food quality control. The optical sensors developed have been characterized by determining the adsorption isotherms on the polymeric layer, based on the sensor response. The sensors based on SPR appear to be really promising due to the optimal sensitivity, low cost and possibility of miniaturization by employing POFs. Moreover, a high selectivity and affinity constant (Kaff), a low LOD and the possibility of the re-use are provided by the successful implementation of MIPs as receptors. Similar optimal results have been obtained by the evanescent wave coupling (EWC) moreover this platform presents the advantages of avoiding the use of Au layer, so could be superior to the SPR ones for the better reproducibility. Also, new kinds of molecularly imprinted materials have been considered in order to improve the biocompatibility of the sensing devices. In particular silk fibroin has been examined for its good optical and mechanical characteristics. Moreover, it is a biomaterial already approved for biomedical applications. Preliminary results on the imprinting of fibroin with glucose have been promising, with an imprinting factor higher than one. Moreover, the imprinted material can easily obtain a thin layer, which is particularly suitable for sensor development

Optoelectronic sensors based on molecularly imprinted polymers

La ricerca è stata incentrata sullo sviluppo di sensori ottici (senza impiego di indicatori) basati su fibre ottiche plastiche (POF). Queste presentano caratteristiche vantaggiose come flessibilità, grande apertura numerica e facile lavorazione; essendo inoltre in grado di sopportare curvature più strette rispetto alle fibre di vetro. Pertanto, le POF risultano adatte alla realizzazione di sensori ottici ad alta sensibilità, miniaturizzati, robusti ed a basso costo. Due approcci differenti sono stati impiegati: il primo è stato basato sullo sviluppo dei sensori direttamente sulle fibre ottiche plastiche (POF) (sensori intrinseci) e il secondo prevede l'impiego di diverse guide d'onda ad esempio in PMMA o PET (sensori estrinseci). I due approcci mostrano caratteristiche distinte per la facile preparazione e sono stati studiati al fine di ottenere una migliore riproducibilità. I sensori sfruttano diversi fenomeni ottici: la risonanza plasmonica di superficie (SPR) o l'accoppiamento di onde evanescenti (EWC). Tutti i sensori impiegano recettori biomimetici sintetici, cioè polimeri a stampo molecolare (MIP) per il rilevamento di analiti in matrici complesse acquose o organiche. I bio-recettori comunemente usati, nonostante la loro elevata selettività e sensibilità, soffrono di grossi svantaggi quali la non disponibilità per tutti i substrati, il limite di analisi in condizioni biologiche e la costosa e lunga procedura per il loro utilizzo. Invece i MIP risultano più resistenti, anche in condizioni di analisi più drastiche (elevate T, bassi pH,…), pur mantenendo affinità e selettività elevate, pari a quelle dei bio-recettori. Tali caratteristiche rendendo questi recettori sintetici utili ai fini sensoristici. Sono stati sviluppati MIP specifici, basati su monomeri funzionali che impiegano interazioni non covalenti con comune composizione riguardo il monomero funzionale e il cross-linker. In alcuni casi, la composizione MIP è stata ottimizzata mediante metodi computazionali considerando diversi monomeri funzionali e cross-linker nonché possibili interazioni interferenti. Le caratteristiche dei MIP, come costante di affinità, capacità di assorbimento e selettività sono state valutate mediante procedura di equilibrazione batch e procedura a flusso. Differenti formulazioni di MIP in forma di particelle porose e sferiche sono state considerate. Sono stati sviluppati e caratterizzati MIP per l'analisi delle seguenti molecole: furaldeide (2-FAL) e dibenzildisolfuro (DBDS) data la loro importanza come utili indicatori dell'usura dei trasformatori di media tensione. La 2-FAL è stata considerata anche in matrici acquose, data la sua rilevanza nel controllo qualità degli alimenti. I sensori ottici sono stati caratterizzati determinando le isoterme di adsorbimento sullo strato polimerico, basato sulla risposta del sensore. I sensori SPR risultano promettenti grazie alla elevata sensibilità, al basso costo e alla possibilità di miniaturizzazione impiegando le POF. Inoltre, l'impiego di MIP come recettore garantiscono un'elevata selettività e costante di affinità (Kaff), un basso LOD e la possibilità del riutilizzo. Simili risultati sono stati ottenuti con sensori basati sull'accoppiamento di onde evanescenti (EWC) che tuttavia risultano più promettenti delle piattaforme SPR presentando il vantaggio dell'eliminazione dello strato di oro e quindi una migliore riproducibilità. Inoltre, nuovi materiali per l'imprinting molecolare sono stati considerati per migliorare la biocompatibilità. In particolare, la fibroina della seta è stata esaminata date le sue ottimali proprietà ottiche e meccaniche ed essendo un biomateriale già approvato per applicazioni biomediche. Risultati preliminari sull'imprinting di fibroina con glucosio sono stati promettenti; riscontrando un fattore di imprinting superiore a uno. Tale materiale stampato è facilmente ottenuto come strato sottile adatto allo sviluppo di sensori.The research was focused on the development of marker-free optical sensors based on plastic optical fibers (POF). These are particularly suitable for sensing application because of their exceptional flexibility, large numerical aperture, and easy manipulation. Also, they are able to withstand smaller bend radii than glass fibers. Therefore, POFs are suitable for the realization of low-cost and miniaturized optical sensors both robust and highly sensitive for application with a remote control. Two approaches have been exploited the first in which the optical platform was directly developed on plastic optical fibers (POF) (intrinsic sensors) and the second that employ different waveguides made for example of PMMA or PET (extrinsic sensors). The two approaches show distinct characteristics of easy preparation and have been investigated to obtain a better reproducibility. In both sensors, different optical phenomena have been exploited, in particular, surface plasmon resonance (SPR) and the evanescent wave coupling (EWC). All the sensors employ synthetic biomimetic receptors, i.e. molecularly imprinted polymers (MIPs) for the detection of analytes in complex aqueous or organic matrices. The most commonly used bio-receptors, despite their high selectivity and sensitivity, suffer from great disadvantages as not being available for all the substrate, being limited to the biological condition of analysis and requiring an expensive and time-consuming development procedure. Instead, MIPs are more resistant, even in harsh conditions of analysis, while maintaining the high affinity and selectivity of the biological receptors, so making these synthetic receptors really promising for sensing purposes. Some specific MIPs have been developed, based on non-covalent interactions template-functional monomers, and with the most common composition as far as the functional monomer and the cross-linker are concerned. In some cases, the MIP composition was optimized by computational methods considering different functional monomers and cross-linkers as well as possible interfering interactions. The MIPs characteristics, as the affinity constant, the capacity of uptake and selectivity have been evaluated by batch procedure and the flow procedure. Porous MIP particles and MIP beads have been considered and characterized by batch equilibration. In particular MIPs for sensing the following molecules have been developed and characterized: 2-FAL (2-furhaldehide) and dibenzyldisulfide (DBDS) because of their rising importance as useful markers of health status of the middle tension transformers in the large distribution energy. 2-FAL was considered in aqueous matrices too, in view of its relevance in food quality control. The optical sensors developed have been characterized by determining the adsorption isotherms on the polymeric layer, based on the sensor response. The sensors based on SPR appear to be really promising due to the optimal sensitivity, low cost and possibility of miniaturization by employing POFs. Moreover, a high selectivity and affinity constant (Kaff), a low LOD and the possibility of the re-use are provided by the successful implementation of MIPs as receptors. Similar optimal results have been obtained by the evanescent wave coupling (EWC) moreover this platform presents the advantages of avoiding the use of Au layer, so could be superior to the SPR ones for the better reproducibility. Also, new kinds of molecularly imprinted materials have been considered in order to improve the biocompatibility of the sensing devices. In particular silk fibroin has been examined for its good optical and mechanical characteristics. Moreover, it is a biomaterial already approved for biomedical applications. Preliminary results on the imprinting of fibroin with glucose have been promising, with an imprinting factor higher than one. Moreover, the imprinted material can easily obtain a thin layer, which is particularly suitable for sensor development

An optic fiber sensor for partial discharge acoustic detection

Partial discharge (PD) is a very common problem in operating power transformers and is one of the factors that could lead to failure of power transformers, leading to power outage and expensive repairs. The acoustic wave induced by PD can be measured and used for monitoring, diagnosing, and locating potential failures in power transformers. The effects of the temperature of the transformer and transformer oil are one of the very important parameters in PD and these effects are investigated in detail. The Fast Fourier Transform (FF1\u27) is used to synthesize the measured data and results show that for periodic PD events, the dominant components of the energy of the PD shift to higher frequencies as the temperature increases. The experimental results are consistent with theoretical expectations. Fiber optic-based sensors have been shown to be attractive devices for PD detection because of a number of inherent advantages including small size, high sensitivity, electrical nonconductivity, and immunity to electromagnetic interference (EMI). A fiber optic sensor based on a Fabry-Perot interferometry is constructed by a simple micromachining process compatible with MEMS (Microelectromechanical system) technology. The sensor is used in a transformer to measure PD acoustic waves. The experimental results show that the sensor not only has an inherent high signal to noise capability, but is able to accurately localize the PD sources inside the transformer

Generator Insulation-Aging On-Line Monitoring Technique Based on Fiber Optic Detecting Technology

The relationship between insulation aging and generator lifespan using fiber optic sensors (FOSs) is explored to ultimately improve asset lifespan through smart choices in running conditions and maintenance. Insulation aging is a major factor that causes generator failure. FOS provides the rare opportunity of being installed up close to the insulation, monitoring degradations that are otherwise difficult to detect. FOSs, unlike purely electrical transducers, are immune to high voltage (HV) and strong electromagnetic (EM) fields. They are small and have a proven long life by their deployment in the Telecom industry. The proposed FOS is a Fabry-Perot cavity made up of two identical fiber Bragg gratings (FBGs) using light wave interference as the working principle. Such architecture delivers simultaneous vibration (10 Hz–1 kHz) and temperature (0.1°C resolution) monitoring, both helping to spot irregular vibration patterns (signatures) and hot-spots inside the generator stator slots. The signal processing unit equipped with a gateway device can help to connect the large volume of sensor data, allowing correlation with the supervisory control and data acquisition (SCADA) system data of the plant. This chapter also elaborates on the field test jointly conducted with Calpine Corporation and Oz Optics, Ltd. (Ottawa, Ontario, Canada)

Design and Modeling of Fiber Optical Current Sensor Based on Magnetostriction

A novel fiber optical current sensor (FOCS) which is based on a giant magnetostrictive material, Terfenol-D (T-D) is modeled and prototyped. Several experiments have been conducted to validate the expected results. Magnetostriction is defined as the change in dimensions of a material under the influence of an external magnetic field. The cause of the change in length is due to the rotation and re-orientation of the small magnetic domains in the magnetostrictive material. The magnetostriction of Terfenol-D is modeled and investigated using several software packages. Here, a magnetostriction-based FOCS using a Terfenol-D/epoxy composite is investigated. Particularly, the FOCS is based on applying magnetostrictive composite material to transform an external magnetic field into a corresponding mechanical strain caused by the magnetostriction of the composite. The composite is incorporated in the FOCS for increased durability, flexibility in shape, extended frequency response, and tensile strength compared to monolithic materials. Coupling Terfenol-D with a fiber Bragg grating (FBG) is an excellent method of magnetic field sensing. It consists of an FBG embedded in the composite that converts magnetostrictive strain into frequency chirp of the optical signal in proportion to a magnetic field. This will form a sensor that is compact, lightweight, and immune from electromagnetic interference. For electromagnetic interference mitigation and optimal signal condition, an FBG, which can be easily integrated with an optical fiber network and reflect a narrow band of wavelengths based on grating periods, is used to encode strain information onto an optical signal. This FOCS has potential in detecting power systems faults due to its advantages over the conventional current transformers. Experiments have been performed to investigate the effect of direct current (DC) and alternate current (AC) on the response of the FOCS. Consistent results that indicate its reliability have been obtained. The experiment results matched the predicted response. The effect of the temperature on the response of the FOCS also has been investigated. Finally, future research directions are presented for the enhancement of the FOCS technology

Terahertz Technology and Its Applications

The Terahertz frequency range (0.1 – 10)THz has demonstrated to provide many opportunities in prominent research fields such as high-speed communications, biomedicine, sensing, and imaging. This spectral range, lying between electronics and photonics, has been historically known as “terahertz gap” because of the lack of experimental as well as fabrication technologies. However, many efforts are now being carried out worldwide in order improve technology working at this frequency range. This book represents a mechanism to highlight some of the work being done within this range of the electromagnetic spectrum. The topics covered include non-destructive testing, teraherz imaging and sensing, among others

Electronic and Photonic Systems WILGA 2014

Symposium Wilga 2014, in its 34th edition, was organized during the last week of May. Symposium is organized under the auspices of SPIE, IEEE, Photonics Society of Poland, WEiTI PW, and PKOpto SEP. The event gathered around 350 persons, mainly young researchers from the  whole country. There were presented around 250 speeches and communications. The main book of Symposium Proceedings is Proc. SPIE vol.9290 which contains around 130 papers. A few tens of papers were also published in technical journals. The leading topics of Wilga 2014 were gathered in key sessions: nano-materials for photonics and electronics, astronomy and space technology, biomedicine, computational intelligence, visualization and multimedia, and large research experiments. The paper presents a digest of some topical tracks, and chosen  work results presented during WILGA 2014 Symposium