Flexible protection architectures using distributed optical sensors

In this paper we describe recent developments in flexible protection schemes that make use of passive fibre Bragg grating (FBG) based transducers for the distributed measurement of voltage and current. The technology underpinning the passive optical approach is described in detail, and both the present development and the future potential of the approach are discussed. In co-operation with Toshiba, the integration of the technique with an existing busbar protection relay is demonstrated, illustrating the flexibility offered by protection schemes that are based on the use of small, passive, multiplexable, dielectric transducers

Distributed photonic instrumentation for smart grids

Photonic sensor networks possess the unique potential to provide the instrumentation infrastructure required in future smart grids by simultaneously addressing the issues of metrology and communications. In contrast to established optical CT/VT technology, recent developments at the University of Strathclyde in distributed point sensors for electrical and mechanical parameters demonstrate an enormous potential for realizing novel and effective monitoring and protection strategies for intelligent electrical networks and systems. In this paper, we review this technology and its capabilities, and describe recent work in power system monitoring and protection using hybrid electro-optical sensors. We show that wide-area visibility of multiple electrical and mechanical parameters from a single central location may be achieved using this technology, and discuss the implications for smart grid instrumentation

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

INE/AUTC 10.0

Intensity based interrogation of optical fibre sensors for industrial automation and intrusion detection systems

In this study, the use of optical fibre sensors for intrusion detection and industrial automation systems has been demonstrated, with a particular focus on low cost, intensity-based, interrogation techniques. The use of optical fibre sensors for intrusion detection systems to secure residential, commercial, and industrial premises against potential security breaches has been extensively reviewed in this thesis. Fibre Bragg grating (FBG) sensing is one form of optical fibre sensing that has been underutilised in applications such as in-ground, in-fence, and window and door monitoring, and addressing that opportunity has been a major goal of this thesis. Both security and industrial sensor systems must include some centralised intelligence (electronic controller) and ideally both automation and security sensor systems would be controlled and monitored by the same centralised system. Optical fibre sensor systems that could be used for either application have been designed, developed, and tested in this study, and optoelectronic interfaces for integrating these sensors with electronic controllers have been demonstrated. The versatility of FBG sensors means that they are also ideal for certain mainstream industrial applications. Two novel transducers have been developed in this work; a highly sensitive low pressure FBG diaphragm transducer and a FBG load cell transducer. Both have been designed to allow interrogation of the optical signal could occur within the housing of the individual sensors themselves. This is achieved in a simple and low cost manner that enables the output of the transducers to be easily connected to standard electronic controllers, such as programmable logic controllers. Furthermore, some of the nonlinear characteristics of FBG sensors have been explored with the aim of developing transducers that are inherently decoupled from strain and temperature interference. One of the major advantages of optical fibre sensors is their ability to be both time division and wavelength division multiplexed. The intensity-based interrogation techniques used here complement this attribute and are a major consideration when developing the transducers and optoelectronic circuits. A time division multiplexing technique, using transmit-reflect detection and incorporating a dual bus, has also been developed. This system architecture enables all the different optical fibre transducers on the network to have the same Bragg wavelength and hence the number of spare replacement transducers required is minimal. Moreover, sensors can be replaced in an online control system without disrupting the network. In addition, by analysing both the transmitted and reflected signals, problems associated with optical power fluctuations are eliminated and the intensity of the sensor signals is increased through differential amplification. Overall, the research addresses the limitations of conventional electrical sensors, such as susceptibility to corrosive damage in wet and corrosive environments, and risk of causing an explosion in hazardous environments, as well as the limitations of current stand-alone optical fibre sensor systems. This thesis supports more alert, reliable, affordable, and coordinated, control and monitoring systems in an on-line environment

Overview of sensors suitable for active flow control methods

Hlavným cieľom tejto bakalárskej práce bolo vytvorenie prehľadu vyvíjaných a už aplikovaných senzorov pre účely aktívneho riadenia prúdov. Senzory musia splňovať niektoré podmienky, preto výber senzorov bol naviazaný na reálnych výsledkoch testovacích programov, popis ktorých tvorí prvú časť tejto bakalárskej práce. Opis technológie a princíp fungovania senzorov je popísaný v druhej časti tejto práce.The main purpose of this bachelor thesis was to create the overview of the sensors developed for the future active flow control applications and overview the sensors already used in the active flow control applications. The sensors have to fulfil several requirements, so selection for the overview was based on the real flight test programs results, which were described in the first part of the thesis. The sensors technology description and operation principles were included in the second part of the thesis

Fiber bragg grating sensors for mainstream industrial processes

This paper reviews fiber Bragg grating sensing technology with respect to its use in mainstream industrial process applications. A review of the various types of sensors that have been developed for industries such as power generation, water treatment and services, mining, and the oil and gas sector has been performed. A market overview is reported as well as a discussion of some of the factors limiting their penetration into these markets. Furthermore, the author’s make recommendations for future work that would potentially provide significant opportunity for the advancement of fiber Bragg grating sensor networks in these mainstream industries

Investigations towards the development of a novel multimodal fibre optic sensor for oil and gas applications.

Oil and gas (O&G) explorations are moving into deeper zones of earth, causing serious safety concerns. Hence, sensing of critical multiple parameters like high pressure, high temperature (HPHT), chemicals, etc., are required at longer distances. Traditional electrical sensors operate less effectively under these extreme environmental conditions and are susceptible to electromagnetic interference (EMI). Compared to electrical sensors, fibre optic sensors offer several advantages like immunity to EMI, electrical isolation, ability to operate in harsh environmental conditions and freedom from corrosion. Existing fibre optical sensors in the O&G industry, based on step index single mode fibres (SMF), offer limited performance, as they operate within a narrow wavelength window. A novel multimodal sensor configuration, based on photonic crystal fibre (PCF) and utilising a multiwavelength approach, is proposed for the first time for O&G applications. This thesis reports computational and experimental investigations into the new multimodal sensing methodology, integrating both optical phase-change and spectral-change based approaches, needed for multi-parameter sensing. It includes investigations to improve the signal-to-noise ratio (SNR) by enhancing the signal intensity attained through structural, material and positional optimisations of the sensors. Waveguide related, computational investigations on PCF were carried out on different fibre optic core-cladding structures, material infiltrations and material doping to improve the signal intensity from the multimodal sensors for better SNR. COMSOL Multiphysics simulations indicated that structural and material modifications of the PCF have significant effects on light propagation characteristics. The propagation characteristics of the PCF were improved by modifying the geometrical parameters, and microstructuring the fibre core and cladding. Studies carried out on liquid crystal PCF (LCPCF) identified its enhanced mode confinement characteristics and wavelength tenability features (from visible to near infrared), which can be utilised for multi-wavelength applications. Enhancing core refractive index of the PCF improved the electric field confinements and thereby the signal intensity. Doping rare earth elements into the PCF core increases its refractive index and also provides additional spectroscopic features (photoluminescence and Raman), leading to a scope for multi-point, multimodal sensors. Investigations were carried out on PCF-FBG (Fibre Bragg grating) hybrid configuration, analysing their capabilities for optical phase-change based, multipoint, multi-parameter sensing. Computational investigations were carried out using MATLAB software, to study the effect of various fibre grating parameters. These studies helped in improving understanding of the FBG reflectivity-bandwidth characteristics, for tuning the number of sensors that can be accommodated within the same sensing fibre and enhancing the reflected signal for improved SNR. A new approach of FBG sensor positioning has been experimentally evaluated, to improve its strain sensitivity for structural health monitoring (SHM) of O&G structures. Further, experimental investigations were carried out on FBGs for sensing multiple parameters like temperature, strain (both tensile and compressive) and acoustic signals. Various spectroscopic investigations were carried out to identify the scope of rare earth doping within the PCF for photoluminescence and Raman spectroscopy based multimodal sensors. Rare earth doped glasses (Tb, Dy, Yb, Er, Ce and Ho) were developed using melt-quench approach and excitation- photoluminescence emission studies were carried out. The studies identified that photoluminescence signal intensity increases with rare earth concentration up to an optimum value and it can be further improved by tuning the excitation source characteristics. Photoluminescence based temperature studies were carried out using the rare earth doped glasses to identify their suitability for O&G high temperature conditions. Raman spectroscopic investigations were carried out on rare earth (Tb) doped glasses, developed using both melt-quench and sol-gel based approaches. Effect of 785 nm laser excitation on Raman signatures and suitability of rare earth doped materials for fibre-based Raman distributed temperature sensing (DTS) were also studied. Finally, a novel multimodal fibre optic sensor configuration is proposed for the O&G applications, consisting of rare earth doped photonic crystal fibre integrating Bragg gratings and operating in multiple wavelength regimes in a multiplexed fashion. The integrated sensor combination is expected to overcome the limitations of existing sensors with regards to SNR, sensing range and multimodal sensing capability