Showing papers by "Neil Gordon published in 2020"

132 kV optical voltage sensor for wide area monitoring, protection and control applications

Abstract: This paper reports on the design, construction and initial testing of a fiber-optic voltage sensor for applications in the field of wide area monitoring, protection and control of high voltage power networks. The 132-kV sensor prototype, combining a capacitive voltage divider (CVD) and an optical low voltage transducer (LVT), was evaluated through laboratory testing and its performance was assessed based on the accuracy requirements specified by the IEC standards for low-power passive voltage transformers. The preliminary results show that the device has the potential to comply with the requirements of the 0,2 class for metering devices, and the 3P and 0,5P classes for protective and multipurpose devices, respectively, as specified by IEC 61869-11. As the device is based on a fiber Bragg grating written in a standard, low-loss, single-mode telecommunication fiber, it has the potential to be deployed as part of a distributed network of sensors along the power network over a wide geographical area, enabling novel power system protection and control strategies.

Femtosecond laser inscribed advanced calibration phantom for optical coherence tomography (OCT)

Abstract: Optical coherence tomography (OCT) has developed rapidly and is widely used in different fields such as biomedicine and optometry. The characterization and calibration of OCT systems is essential when testing the system and during normal use to ensure that there is no misalignment or distortion that could affect clinical decisions. Imaging distortion is a significant challenge for OCT systems when viewing through non-planar surfaces. Here we present a new multi-purpose plano-convex OCT phantom which is designed to be used for OCT characterization and calibration as well as to validate the post-processing algorithm for the imaging distortion of the OCT systems. A femtosecond laser direct writing technique is used to fabricate this phantom which consists of a landmark layer with radial lines at a 45-degree angular spacing inscribed at 50μm in apparent depth (AD) underneath the planar surface. Below that there are a further 8 layers of a spherical inscription pattern which has a 150μm (in AD) separation between each layer. The first spherical layer is located at 150μm (in AD) underneath the planar surface. Due to the laser power loss when travelling through the deeper layer, an increased power is applied to the deeper layers. The spherical pattern overcomes orientation issues seen with existing calibration phantoms. The landmark layer is applied so that it can easily tell the exact location when scanning which will also benefit the image distortion correction process.

Methods and apparatus for time-stamping a signal

Abstract: time-stamping of received signals and/or measurements derived from those signals at a location away from the actual measurement locations, and eliminating the requirement for power supplies, GPS equipment, and telecommunication equipment at each measurement location by determining a time t at which the signal is received from a voltage/current sensor 103, determining a time delay ts corresponding to the sensor and determining a time at which the signal originated from the sensor by deducting the time delay from the time at which the signal is received. These signals are received from appropriate sensors distributed along optical fibres such as may be incorporated in modern power cables. The voltage/current sensor may comprise a fibre Bragg grating in contact with a piezoelectric element which expands and contracts responsive to a sensed current or voltage, wherein the sensed voltage/current is determined from a spectral position of a peak reflection wavelength from the fibre Bragg grating.