Oscillations in electrical power networks

Patent metadata

Field	Value
Publication number	US-11025065-B2
Application number	US-201716072194-A
Country	US
Kind code	B2
Filing date	Jan 20, 2017
Priority date	Jan 26, 2016
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

The present invention relates to a method of monitoring oscillations that are liable to interact in an electrical power network, in dependence on measurement of AC waveforms in the electrical power network. The method comprises receiving first waveform data corresponding to an electrical quantity in each phase of at least two phases of three-phase AC waveforms at a location in the electrical power network. The method further comprises applying a transformation to the first waveform data to provide therefrom second waveform data corresponding to an electrical quantity at the location in a single phase representation, the second waveform data depending on the at least two phases.

First claim

The invention claimed is:

1. A method of monitoring oscillations that are liable to interact in an electrical power network, in dependence on measurement of AC waveforms in the electrical power network, the method comprising:
receiving first waveform data corresponding to an electrical quantity in each phase of at least two phases of three-phase AC waveforms at a location in the electrical power network;
subsequent to the receiving, determining whether or not there is a measurement interruption, the measurement interruption indicative that some of the first measurement data is invalid, and ignoring the invalid first measurement data;
applying a transformation to at least some of the first waveform data to provide therefrom second waveform data corresponding to an electrical quantity at the location in a single phase representation, the second waveform data depending on the at least two phases;
subsequent to the applying, sending the second waveform data to a control center;
analyzing the second waveform data at the control center for the presence of sub-synchronous oscillations, the sub-synchronous oscillations potentially interacting to create an adverse resonant condition in the electrical power network;
based upon the analyzing, taking an action that addresses or prevents the adverse resonant condition in the electrical power network, the action being one of: changing a parameter of an element in the electrical power network or reconfiguring the electrical power network.

2. The method according to claim 1 , in which the transformation is operative to project data for the at least two phases from a three-phase coordinate system onto a two axes reference frame.

3. The method according to claim 1 , in which the transformation is the Clarke transformation.

4. The method according to claim 1 , in which the step of receiving first waveform data comprises receiving first waveform data corresponding to an electrical quantity in each phase of three phases of three-phase AC waveforms at the location in the electrical power network and the transformation is operative on the first waveform data corresponding to an electrical quantity in each phase of the three phases to provide second waveform data corresponding to an electrical quantity in one phase only.

5. The method according to claim 1 , in which the transformation is the Clarke transformation and three phases are subject to transformation, the transformation having the form:

D
α

⁡

(
t
)

=

2
3

⁡

[

1

-

1
2

-

1
2

]

⁡

[

D
a

⁡

(
t
)

D
b

⁡

(
t
)

D
c

⁡

(
t
)

]

where D is either current where current is measured, or voltage where voltage is measured.

6. The method according to claim 1 , in which the transformation is the Clarke transformation and two phases only are subject to transformation, the transformation having the form:

D
β

⁡

(
t
)

=

2
3

⁡

[

3

2

-

3

2

]

⁡

[

D
a

⁡

(
t
)

D
b

⁡

(
t
)

]

where D is either curr

Assignees

• General Electric Technology Gmbh

Inventors

• Maleka Kyriaki
• Bagleybter Oleg
• Al-Ashwal Natheer
• Clark Stuart
• Wilson Douglas

Classifications

• H02J13/333

  the equipment forming part of substations · CPC title

• H02J13/12

  Monitoring network conditions, e.g. electrical magnitudes or operational status · CPC title

• H02J3/00144

  using phasor measuring units [PMU] · CPC title

• H02J3/0014

  for preventing or reducing power oscillations in networks · CPC title

• G01R19/2506 Primary

  Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values (G01R19/003 takes precedence); Details concerning sampling, digitizing or waveform capturing (displaying waveforms G01R13/00; analog sampling G01R19/0053) · CPC title