Providing a frequency of an electrical quantity in an electrical power system
AssigneeHitachi Energy Ltd
InventorTord Bengtsson
Life of this patent
Estimating the term…
Abstract
A method for providing a frequency of an electrical quantity in an electrical power system comprises obtaining, with respect to a first time, a first discrete Fourier transform (DFT) phasor of an electrical quantity in the electrical power system, estimating a second DFT phasor at a time interval before the first time, where the time interval depends on an approximated frequency, and determining the frequency at the first time based on the first and the second DFT phasor.
Claims20
A method for providing a frequency of an electrical quantity in an electrical power system, the method comprising:
- obtaining, with respect to a first time at which the electrical quantity is sampled, a first discrete Fourier transform (DFT) phasor of the electrical quantity in the electrical power system,
- estimating a second DFT phasor at a first time interval before the first time, said first time interval depending on an approximated frequency, wherein the second DFT phasor is estimated by interpolation using DFT phasors obtained at sampling times around the time at which the second DFT phasor is to be estimated,
- determining the frequency (fnew) at the first time based on the first and the second DFT phasor, and
- control the electrical power system based on the determined frequency, wherein the control comprises one or more of controlling a circuit breaker, disconnecting a load, or restoring a frequency of the electrical power system.
A phasor processing device for use in an electrical power system, the phasor processing device comprising a processor configured to:
- obtain, with respect to a first time at which an electrical quantity is sampled, a first discrete Fourier transform (DFT) phasor of the electrical quantity in the electrical power system,
- estimate a second DFT phasor at a first time interval before the first time, said first time interval depending on an approximated frequency, wherein the second DFT phasor is estimated by interpolation using DFT phasors obtained at sampling times around the time at which the second DFT phasor is to be estimated, and
- determine the frequency (fnew) at the first time based on the first and the second DFT phasor, and
- control the electrical power system based on the determined frequency, wherein the control comprises one or more of controlling a circuit breaker, disconnecting a load, or restoring a frequency of the electrical power system.
A non-transitory computer-readable medium storing computer program code for providing a frequency of an electrical quantity in an electrical power system, said computer program code configured to cause a processor to, when said computer program code is being operated upon by the processor:
- obtain, with respect to a first time at which the electrical quantity is sampled, a first discrete Fourier transform (DFT) phasor of the electrical quantity in the electrical power system,
- estimate a second DFT phasor at a first time interval before the first time, said first time interval depending on an approximated frequency, wherein the second DFT phasor is estimated by interpolation using DFT phasors obtained at sampling times around the time at which the second DFT phasor is to be estimated, and
- determine the frequency (fnew) at the first time based on the first and the second DFT phasor, and
- control the electrical power system based on the determined frequency, wherein the control comprises one or more of controlling a circuit breaker, disconnecting a load, or restoring a frequency of the electrical power system.
Dependencies are inferred from the claim text.