Method and system for analysis of electric power transmission link status

• US 6,167,525 A
• Filed: 02/25/1998
• Issued: 12/26/2000
• Est. Priority Date: 02/26/1997
• Status: Expired due to Term

• Current Assignee: Prysmian Cavi E Sistemi Italia Srl (Prysmian SPA)
• Original Assignee: Pirelli Cavi e Sistemi S.P.A. (Prysmian SPA)
• Inventors: Gaspari, Roberto, Donazzi, Fabrizio
• Primary Examiner(s): Ray, Gopal C.
• Application Number:
  US09/030,509
• Time in Patent Office: 1,035 Days
• Field of Search: 713/300, 713/330, 713/340, 340/825.06, 340/870.17, 340/538, 340/870.16, 307/31-39, 307/115, 324/126, 324/127, 324/105, 324/106, 361/124, 361/93, 374/163, 702/108, 385/100, 385/115
• US Class Current: 361/93.8
• CPC Class Codes: H02J 13/00012 using an auxiliary transmission line
• CPC Class Codes: H02J 13/00017 using optical fiber
• CPC Class Codes: H02J 13/00034 the elements or equipment being or involving an electric power substation

Abstract

A method and system for transporting electric power in a link and for the analysis of the status of an electric power transmission link and the relevant current rating capability control. The method includes dividing the link into a predetermined number of segments, each segment having an associated prediction model and at least two associated temperature sensors. Upon receiving sensor values, an expected operating condition in one of the segments is determined based on the sensor value and the electric current value. Next, an actual operating condition in the segment is determined and compared with the expected operating condition. If there is a difference between the conditions, a second predetermined prediction model is associated with the segment.

Claims

1. Method for transporting electric power in a current conducting link comprising:

supplying an electric current of predetermined value in the link;

dividing said link into a predetermined number of segments;

associating a first predetermined prediction model to each of said segments;

laying a plurality of temperature sensors along the link, at least two of said sensors being operatively associated with each of said segments and being affected by said current value;

getting respective sensor values from said sensors at a first time;

determining an expected operating condition in one of said segments at a second time as a function of said sensor values at said first time and of said electric current value, according to said first prediction model associated with said segment;

determining an actual operating condition in said segment at said second time associated to sensor values generated at said second time;

comparing said actual operating condition with said expected operating condition;

associating, or having associated, a second predetermined prediction model with said segment or a subsegment thereof in presence of a difference between said actual operating condition and said expected operating condition exceeding a predetermined value.

2. Method according to claim 1, wherein said phase of associating, or having associated, a second predetermined prediction model comprises the phase of dividing, or having divided, said segment into at least two subsegments, each subsegment being associated with at least one sensor, in presence of a difference between said actual operating condition and said expected operating condition exceeding a predetermined value.

3. Method according to claim 1, further comprising the step of regulating said electric current value so as to maintain an expected operating condition of the segment at a selected time within a predetermined value.

4. Method according to claim 3, wherein the step of regulating the electric current value includes re-routing the current within the link to reduce the current rate in a segment in the link.

5. Method according to claim 1, wherein the step of determining an expected operating condition includes:

recording a number of sensor values measured at respective times earlier than a given time;

evaluating the expected operating condition of the segment at said second time according to said first model as a function of said sensor values at said first time, of said electric current value and of said recorded sensor values.

6. Method according to claim 1, wherein said link includes an insulated electric cable of predetermined length, said insulated electric cable including at least one segment.

7. Method according to claim 6, wherein said operating condition of the segment associated to said sensor values includes the temperature in a point inside the cable insulation in a selected longitudinal location along the cable.

8. Method according to claim 6, wherein said sensor values include a longitudinal profile of the temperature along the segment, measured at a predetermined radial distance from the cable conductor.

9. Method according to claim 8, wherein said longitudinal profile of the temperature along the segment is measured at cable surface.

10. Method according to claim 1, wherein said operating condition of the segment associated to said sensor values includes the temperature in a predetermined location in the segment.

11. Method according to claim 1, wherein said sensor values at the first time and said sensor values at the second time include a longitudinal thermal profile along the segment, measured with a predetermined longitudinal resolution.

12. Method according to claim 11, wherein said profile of the temperature includes an optical time domain reflectometry (OTDR) trace obtained through an optical fibre operatively associated with said segment.

13. Method according to claim 11, wherein said subsegment associated to said second prediction model is longitudinally extended for a length including at least the portion of said profile where the expected temperature determined from said first sensor values and said first prediction model is different from the actual temperature determined from said second sensor values and said first prediction model.

14. Method according to claim 1, wherein each of said segments has an expected substantially uniform thermal behaviour.

15. Method according to claim 1, wherein the step of determining the actual operating condition is repeated at a predetermined time frequency.

16. Method according to claim 1, wherein the step of determining the operation condition of the segment includes determining the temperature in a predetermined number of locations in the segment and choosing the highest of said determined temperatures as the operation condition of the segment.

17. Method according to claim 1, wherein the step of determining the actual operating condition of the segment associated to said sensor values includes:

getting a number of sensor values at a time;

determining a number of status parameters associated to said sensor values;

selecting a critical value among said status parameters;

evaluating the operating condition of the segment as a function of said critical value.

18. Method according to claim 1, wherein the step of further comprises operating a thermal control means associated with said segment to maintain the operating condition in said segment within a predetermined value.

19. Method according to claim 1, wherein the steps of determining both the expected and actual operating conditions of the segment associated to said sensor values of both the first and second times comprises the step of locating a place along said segment where said sensor values of both the first and second times are measured.

20. Method according to claim 1, further comprising the step of getting further sensor values relating to the thermal exchange capability of the segment.

21. System for transporting electric power comprising:

a link including at least an electrical cable;

a generator supplying electrical power into said link;

a plurality of sensors operatively associated with said link, said sensors forming a longitudinally distributed temperature sensor;

a data acquisition unit connected to said sensors;

a data processing unit operatively associated with said data acquisition unit;

a control actuator operatively associated with said data processing unit, said control actuator being such as to generate a control signal responsive to data generated by said sensors as processed by said data processing unit, wherein said control signal is a regulation signal acting on said generator.

22. The system according to claim 21 wherein said optical fibre is located in proximity to said electrical cable.

23. The system according to claim 21 wherein said optical fibre is located inside said electrical cable.

24. The system according to claim 21, wherein said longitudinally distributed temperature sensor includes an optical fiber.

25. The system according to claim 24, further comprising an optical time domain reflectometry apparatus connected to said optical fiber that determines a temperature profile of said electrical cable using a pulsed light transmitted in said optical fiber.

26. The system according to claim 21, where said plurality of sensors comprises a plurality of thermocouples.

27. System for transporting electric power comprising:

a link including at least an electrical cable;

a generator supplying electrical power into said link;

a plurality of sensors operatively associated with said link, said sensors forming a longitudinally distributed temperature sensor;

a data acquisition unit connected to said sensors;

a data processing unit operatively associated with said data acquisition unit a control actuator operatively associated with said data processing unit, said control actuator being such as to generate a control signal responsive to data generated by said sensors as processed by said data processing unit, wherein said control signal is a regulation signal acting on thermal control means to associate to a portion of said link.