Electric power transmission network state estimation

• US 20030120440A1
• Filed: 12/09/2002
• Published: 06/26/2003
• Est. Priority Date: 12/21/2001
• Status: Active Grant

• Current Assignee: ABB Power Grids Switzerland AG (ABB Limited)
• Original Assignee: ABB Research Ltd. (ABB Ltd.)
• Inventors: Zima, Marek, Rehtanz, Christian
• Granted Patent: US 7,069,159 B2
• Time in Patent Office: Days
• US Class Current: 702/57
• CPC Class Codes: H02H 3/40 responsive to ratio of voltage and current
• CPC Class Codes: H02H 6/005 using digital thermal images
• CPC Class Codes: H02H 7/22 for distribution gear, e.g. bus-bar systems; for switching devices detecting mechanical or electrical defects in gas-insulated switchgears H02B13/065
• CPC Class Codes: H02J 3/00 Circuit arrangements for ac mains or ac distribution networks
• CPC Class Codes: Y02E 40/70 Smart grids as climate change mitigation technology in the energy generation sector
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/00 Systems supporting electrical power generation, transmission or distribution
• CPC Class Codes: Y04S 10/22 Flexible AC transmission systems [FACTS] or power factor or reactive power compensating or correcting units

Abstract

In a method, computer program and system for estimating a state of an electric power transmission network, time-stamped phasor measurements are made by phasor measurement units (1) located at a first set of locations (11,12) throughout the network, and a plurality of voltage and/or current phasors at a second set of locations is estimated, where the locations of the first (11,12) and second sets of locations are distant from one another, and a status of network elements (L4,L5,13) that are remotely located from the phasor measurement units is inferred from the phasor measurements and the estimated phasors.

In a preferred variant of the invention, the network elements are transmission lines (L1 . . . L8), switchgear, under load tap changing transformers, compensation devices (13) or FACTS devices, and the status information describes whether a network element (L4,L5,13) is electrically connected to or disconnected from the network.

Claims

1. A method for estimating a state of an electric power transmission network, in which time-stamped phasor measurements are made by phasor measurement units (1) located at a first set of locations (11,12) throughout the network, characterized in that

a plurality of voltage and/or current phasors at a second set of locations is estimated, and wherein the locations of the first (11,12) and second sets of locations are distant from one another, and

that a status of network elements (L4,L5,13) that are remotely located from the phasor measurement units (1) is inferred from the phasor measurements and the estimated phasors.

2. The method according to claim 1, in which voltages and/or currents at a substation that is not equipped with phasor measurement units (1) is estimated.

3. The method according to one of the preceding claims, in which a state of the network comprising load and current flows of the network is estimated from the measured and estimated voltages and currents and from an estimated topology of the network.

4. The method according to one of the preceding claims, in which the network elements comprise switchgear and the status of network elements comprises information on whether a switch is open or closed.

5. The method according to one of the preceding claims, in which the network elements comprise transmission lines (L1 . . . L8) and the status of network elements comprises information on whether a transmission line is disconnected or in service.

6. The method according to one of the preceding claims, in which the network elements comprise under load tap changing transformers and the status of network elements comprises information on a tap ratio of the transformer.

7. The method according to one of the preceding claims, in which the network elements comprise at least one compensation device (13) or FACTS device and the status of network elements comprises information on whether said device is electrically connected to or disconnected from the network.

8. A computer program for estimating a state of an electric power transmission network loadable into an internal memory of a digital computer, comprising computer program code means to make, when said program is loaded in the computer, the computer execute a procedure for processing time-stamped phasor measurements originating from phasor measurement units (1) located at a first set of locations (11,12) throughout the network, characterized in that the program is configured to

compute a plurality of estimated voltage and/or current phasors at a second set of locations, the locations of the first (11,12) and second sets of locations being distant from one another, and to

compute, from the phasor measurements and from the estimated s phasors, a status of network elements (L4,L5,13) that are remotely located from the phasor measurement units.

9. A system for estimating a state of an electric power transmission network from time-stamped phasor measurements that originate from phasor measurement units (1) located at a first set of locations (11,12) throughout the network, characterized in that

the system comprises a data processing device configured to compute a plurality of estimated voltage and/or current phasors at a second set of locations, the locations of the first (11,12) and second sets of locations being distant from one another, and to

compute, from the phasor measurements and from the estimated phasors, a status of network elements (L4,L5,13) that are remotely located from the phasor measurement units.

10. The system according to claim 9, wherein the data processing device is configured to estimate voltages and/or currents at a substation that is not equipped with phasor measurement units (1).