Abstract: An electrical apparatus comprises a chain-link converter which includes a plurality of chain-link sub-modules each of which is operable to provide a voltage source. The electrical apparatus also includes a switching control unit to control the chain-link sub-modules. The switching control unit is operatively interconnected with each chain-link sub-module by an electromagnetic radiation conduit. The length of the electromagnetic radiation conduit between the switching control unit and at least one chain-link sub-module differs from the length of the electromagnetic radiation conduit between the switching control unit and at least one other chain-link sub-module. The switching control unit is configured to discern a difference in the time taken for an electromagnetic signal to propagate through each different-length electromagnetic radiation conduit to thereby identify the or each chain-link sub-module associated with each different-length electromagnetic radiation conduit.

Abstract: A method of identifying a faulty sub-module of a chain-link converter is provided, wherein the chain-link converter includes a plurality of sub-modules with each sub-module including at least one switching element and an energy storage device which together are selectively operable to provide a voltage source. The method comprises the steps of: measuring a switching characteristic of each sub-module of the chain-link converter; establishing a switching characteristic signature of the chain-link converter; and identifying the or each sub-module with a switching characteristic that deviates from the switching characteristic signature as being a faulty sub-module.

Abstract: A method of identifying a faulty sub-module of a chain-link converter is provided, wherein the chain-link converter includes a plurality of sub-modules with each sub-module including at least one switching element and an energy storage device which together are selectively operable to provide a voltage source. The method comprises the steps of: measuring a switching characteristic of each sub-module of the chain-link converter; establishing a switching characteristic signature of the chain-link converter; and identifying the or each sub-module with a switching characteristic that deviates from the switching characteristic signature as being a faulty sub-module.

Abstract: A method for estimating a parameter includes: generating an optical signal, the optical signal modulated via a modulation signal; transmitting the modulated optical signal from a light source into an optical fiber, the optical fiber including a plurality of sensing locations disposed along the optical fiber and configured to reflect light; receiving a reflected signal including light reflected from the plurality of sensing locations; and combining, in parallel, each of a plurality of reference signals with the reflected signal to estimate a value of the parameter.

Abstract: An electrical apparatus comprises a chain-link converter which includes a plurality of chain-link sub-modules each of which is operable to provide a voltage source. The electrical apparatus also includes a switching control unit to control the chain-link sub-modules. The switching control unit is operatively interconnected with each chain-link sub-module by an electromagnetic radiation conduit. The length of the electromagnetic radiation conduit between the switching control unit and at least one chain-link sub-module differs from the length of the electromagnetic radiation conduit between the switching control unit and at least one other chain-link sub-module. The switching control unit is configured to discern a difference in the time taken for an electromagnetic signal to propagate through each different-length electromagnetic radiation conduit to thereby identify the or each chain-link sub-module associated with each different-length electromagnetic radiation conduit.

Abstract: A method for estimating a parameter includes: transmitting a control signal to a coherent optical source, the control signal configured to chaotically vary an output of the optical source and generate a chaotically excited optical signal; transmitting the optical signal from the optical source into an optical fiber, the optical fiber including at least one sensing location; receiving a reflected signal including light reflected from the at least one sensing location; and estimating a value of the parameter using the reflected signal.

Abstract: A method for estimating a distance includes: generating an optical signal having a wavelength that is within a wavelength range, the optical signal modulated via a modulation signal having a modulation frequency; transmitting the modulated optical signal from a light source into the optical fiber, the optical fiber in contact with a moveable strain inducing element located at the position along the optical fiber, the optical fiber including a plurality of sensing locations configured to reflect light within the wavelength range when under strain from the strain inducing element and transmit light within the wavelength range when not under strain from the strain inducing element; receiving a reflected signal including light reflected from at least one of the sensing locations; demodulating the reflected signal with a reference signal to generate reflected signal data; and determining the distance to the position along the optical fiber based on the reflected signal data.

Abstract: An apparatus for estimating a parameter includes: an optical fiber including at least one core configured to transmit an interrogation signal and including a plurality of sensing locations distributed along a measurement length of the optical fiber and configured to reflect light; a reference optical path configured to transmit a reference signal, the reference optical path disposed in a fixed relationship to the at least one core and extending at least substantially parallel to the at least one core, the reference optical path including a reference reflector that defines a cavity length corresponding to the measurement length; a detector configured to receive a reflected return signal; a reference interferometer configured to receive at least a reference signal and generate an interferometric reference signal; and a processor configured to apply the interferometric reference signal to the reflected return signal to compensate for one or more environmental parameters.

Abstract: A method for estimating a distance includes: generating an optical signal having a wavelength that is within a wavelength range, the optical signal modulated via a modulation signal having a modulation frequency; transmitting the modulated optical signal from a light source into the optical fiber, the optical fiber in contact with a moveable strain inducing element located at the position along the optical fiber, the optical fiber including a plurality of sensing locations configured to reflect light within the wavelength range when under strain from the strain inducing element and transmit light within the wavelength range when not under strain from the strain inducing element; receiving a reflected signal including light reflected from at least one of the sensing locations; demodulating the reflected signal with a reference signal to generate reflected signal data; and determining the distance to the position along the optical fiber based on the reflected signal data.

Abstract: A method for estimating a parameter includes: transmitting a control signal to a coherent optical source, the control signal configured to chaotically vary an output of the optical source and generate a chaotically excited optical signal; transmitting the optical signal from the optical source into an optical fiber, the optical fiber including at least one sensing location; receiving a reflected signal including light reflected from the at least one sensing location; and estimating a value of the parameter using the reflected signal.

Abstract: A method for estimating a parameter includes: generating an optical signal, the optical signal modulated via a modulation signal; transmitting the modulated optical signal from a light source into an optical fiber, the optical fiber including a plurality of sensing locations disposed along the optical fiber and configured to reflect light; receiving a reflected signal including light reflected from the plurality of sensing locations; and combining, in parallel, each of a plurality of reference signals with the reflected signal to estimate a value of the parameter.

Abstract: An apparatus for estimating a parameter includes: an optical fiber including at least one core configured to transmit an interrogation signal and including a plurality of sensing locations distributed along a measurement length of the optical fiber and configured to reflect light; a reference optical path configured to transmit a reference signal, the reference optical path disposed in a fixed relationship to the at least one core and extending at least substantially parallel to the at least one core, the reference optical path including a reference reflector that defines a cavity length corresponding to the measurement length; a detector configured to receive a reflected return signal; a reference interferometer configured to receive at least a reference signal and generate an interferometric reference signal; and a processor configured to apply the interferometric reference signal to the reflected return signal to compensate for one or more environmental parameters.

Abstract: A method for estimating a parameter includes: generating an optical signal, the optical signal modulated via a modulation signal having a variable modulation frequency over a period of time; transmitting the modulated optical signal from a light source into an optical fiber, the optical fiber including at least one sensing location configured to reflect light; receiving a reflected signal including light reflected from the at least one sensing location; and demodulating the reflected signal with a reference signal, the reference signal including a time delay relative to the modulation signal based on a distance between the light source and the at least one sensing location.

Abstract: A system for measuring downhole parameters is disclosed. The system includes: a carrier configured to be disposed in a borehole in an earth formation; at least one optical fiber sensor in operable communication with the carrier; a measurement assembly including an electromagnetic signal source configured to transmit a first interrogation signal into the optical fiber sensor and a detector configured to receive a reflected signal indicative of a downhole parameter in response to the interrogation signal; and a processor configured to automatically receive scattered signals from the optical fiber sensor, generate distributed scattering data indicative of a condition of the optical fiber sensor and analyze changes in the distributed scattering data to identify changes in the condition of the optical fiber sensor.