Abstract: When implementing a PMU network, creation of synchrophasors is achieved by centralising the determining of phasors and corresponding time-stamps at a location away from the actual measurement locations. Alternatively, or in addition to time-stamping phasors, time-stamping of any received signals and/or measurements derived from those signals is enabled. These signals are received from appropriate sensors distributed along optical fibres such as may be incorporated in modern power cables. Likewise, control signals can be communicated along optical fibres such as may be incorporated in modern power cables, and a number of approaches to ensuring control signals are received by the intended control modules are provided. Either or both the PMU network and control system can be implemented in a power network by exploiting existing optical fibre infrastructure in this way, and control signals can be transmitted dependent on analysis performed on synchrophasors.

Abstract: The invention enables an optical voltage sensor, comprising a piezoelectric actuator mechanically coupled to an optical strain sensor (such as a fibre Bragg grating), to withstand lightning impulses, the effects of which would otherwise be harmful or destructive to the piezoelectric actuator and/or other sensitive components. As such, the optical voltage sensor, comprised within a photonic voltage transducer which also comprises a lightning impulse attenuator, is able to comply with relevant standards and be used for applications in power networks and exposed to the highest voltages for equipment.

Abstract: The invention enables the measurement of the voltage between phases (phase-to-phase voltages) of a multi-phase power cable, e.g. a three-phase power cable, such as may be used in subsea or subterranean environments for electrical power transfer. The invention does not require a power supply at the measurement location, and relies solely on optical fibres (typically present in such cables) to carry light to and from the sensors. Fibre Bragg grating (FBG) based sensors sample the electric field between conductors and convert to a strain on the fibre, as a result of which certain wavelengths of the reflected light are modulated by the instantaneous magnitude of the phase-to-phase voltages to be measured. A sensor module embodying the invention includes a spacer which holds the conductors in a predetermined geometry and locates the FBG sensors between pairs of conductors on which the phase-to-phase voltage measurements are to be performed.

Abstract: The invention enables the complexity and cost of implementing a PMU network and/or a control system to be substantially reduced by eliminating the requirement for power supplies, GPS equipment, and telecommunication equipment at each measurement and/or control location. In the case of implementing a PMU network, creation of synchrophasors is achieved by centralising the determining of phasors and corresponding time-stamps at a location away from the actual measurement locations. Alternatively, or in addition to time-stamping phasors, the invention enables the time-stamping of any received signals and/or measurements derived from those signals. These signals are received from appropriate sensors distributed along optical fibres such as may be incorporated in modern power cables. Likewise, control signals can be communicated along optical fibres such as may be incorporated in modern power cables, and a number of approaches to ensuring control signals are received by the intended control modules are provided.

Abstract: The invention enables the measurement of the voltage between phases (phase-to-phase voltages) of a multi-phase power cable, e.g. a three-phase power cable, such as may be used in subsea or subterranean environments for electrical power transfer. The invention does not require a power supply at the measurement location, and relies solely on optical fibres (typically present in such cables) to carry light to and from the sensors. Fibre Bragg grating (FBG) based sensors sample the electric field between conductors and convert to a strain on the fibre, as a result of which certain wavelengths of the reflected light are modulated by the instantaneous magnitude of the phase-to-phase voltages to be measured. A sensor module embodying the invention includes a spacer which holds the conductors in a predetermined geometry and locates the FBG sensors between pairs of conductors on which the phase-to-phase voltage measurements are to be performed.

Abstract: A monitoring system for monitoring a plurality of fiber Bragg gratings in an optical fiber, each fiber Bragg grating being sensitive to a different wavelength of light. The system comprises a broadband source for illuminating the optical fiber; at least one optical interferometer; light feeding means for feeding to an input of the interferometer light reflected from the fiber Bragg gratings, and a processor for processing the output from the interferometer to determine the wavelength of the reflected light. The light feeding means comprise a wavelength division multiplexer operable to separate light received from the optical fiber into a plurality of wavelengths, each associated with one of the fiber Bragg gratings and/or a time division mulitplexer operable to separate light received from the optical fiber into in a time separated series.

Abstract: A monitoring system for monitoring a plurality of fibre Bragg gratings in an optical fibre, each fibre Bragg grating being sensitive to a different wavelength of light. The system comprises a broadband source for illuminating the optical fibre; at least one optical interferometer; light feeding means for feeding to an input of the interferometer light reflected from the fibre Bragg gratings, and a processor for processing the output from the interferometer to determine the wavelength of the reflected light. The light feeding means comprise a wavelength division multiplexer operable to separate light received from the optical fibre into a plurality of wavelengths, each associated with one of the fibre Bragg gratings and/or a time division mulitplexer operable to separate light received from the optical fibre into in a time separated series.

Abstract: A combined pressure and temperature sensor, the sensor comprising at least one first optical sensing element of a first type and at least one second optical sensing element of a second type, wherein the sensor is adapted to compensate for temperature and/or pressure effects in the first or second optical sensing element using a response of the other of the second or first optical sensing elements.

Abstract: A system for measuring simultaneously both temperature and ac voltage and/or ac current, the system comprising: a piezo-electric sensor; and optical fiber that includes an optical strain sensor being in contact with the piezo-electric sensor and able to expand or contract therewith and an analyzer for analyzing an optical output of the fiber and strain sensor in response to an optical input, the analyzer being operable to use the optical output to determine the temperature and the ac voltage and/or ac current.

Abstract: A system for measuring simultaneously both temperature and ac voltage and/or ac current, the system comprising: a piezo-electric sensor; and optical fiber that includes an optical strain sensor being in contact with the piezo-electric sensor and able to expand or contract therewith and an analyzer for analyzing an optical output of the fiber and strain sensor in response to an optical input, the analyzer being operable to use the optical output to determine the temperature and the ac voltage and/or ac current.