STATIC ELECTRIC INDUCTION SYSTEM AND METHOD

Abstract

A sialic electric induction system is provided. The static electric induction system includes a heat generating electric component; a dielectric cooling fluid; a cooling passage structure along the electric component; and a pump arrangement arranged to alternatingly be controlled in a first mode and in a second mode. In the first mode, the pump arrangement pumps the dielectric cooling fluid to be driven through the cooling passage structure in a forward direction to cool the electric component, and in the second mode, the pump arrangement pumps the dielectric cooling fluid to be driven through the cooling passage structure in a reverse direction, opposite to the forward direction, to cool the electric component. A method of controlling a static electric induction system is also provided.

Claims

1. A static electric induction system comprising: heat generating electric component; dielectric cooling fluid; cooling passage structure along the electric component; and pump arrangement arranged to alternatingly be controlled in a first mode and in a second mode, wherein in the first mode, the pump arrangement pumps the dielectric cooling fluid to be driven through the cooling passage structure in a forward direction to cool the electric component, and wherein in the second mode, the pump arrangement pumps the dielectric cooling fluid to be driven through the cooling passage structure in a reverse direction, opposite to the forward direction, to cool the electric component; wherein the dielectric cooling fluid is a dielectric liquid with Prandtl number above 20 in a temperature range of operation of the electric component.

2. The static electric induction system according to claim 1, further comprising a winding, wherein the electric component is a cable turn of the winding, and wherein the cooling passage structure is arranged along the winding from a bottom part of winding to a top part of the winding.

3. The static electric induction system according to claim 2, wherein the cooling passage structure extends along at least 90% of a height of the winding.

4. The static electric induction system according to claim 1, wherein the cooling passage structure comprises two vertical sections and at least one horizontal section interconnecting the vertical sections, wherein the dielectric cooling fluid is driven upwards in each vertical section when the pump arrangement is controlled in the first mode, and wherein the dielectric cooling fluid is driven downwards in each vertical section when the pump arrangement is controlled in the second mode.

5. The static electric induction system according to claim 1, further comprising a suction chamber arranged above the electric component.

6. The static electric induction system according to claim 5, wherein the suction chamber is arranged to suck the dielectric cooling fluid from the cooling passage structure into the suction chamber when the pump arrangement is controlled in the first mode, and arranged to discharge the dielectric cooling fluid from the suction chamber into the cooling passage structure when the pump arrangement is controlled in the second mode.

7. The static electric induction system according to claim 6, further comprising a substantially closed upper passage between the suction chamber and the pump arrangement.

8. The static electric induction system according to claim 1, further comprising an enclosure, and wherein the electric component is arranged inside the enclosure.

9. The static electric induction system according to claim 8, further comprising a closed lower passage between the pump arrangement and the enclosure.

10. The static electric induction system according to claim 8, wherein the enclosure comprises a bottom section below the electric component, and wherein the bottom section and the cooling passage structure are arranged such that the dielectric cooling fluid is driven from the bottom section into the cooling passage structure when the pump arrangement is controlled in the first mode, and such that the dielectric cooling fluid is driven from the cooling passage structure into the bottom section when the pump arrangement is controlled in the second mode.

11. The static electric induction system according to claim 1, wherein the pump arrangement comprises a reversible pump.

12. The static electric induction system according to claim 1, wherein the dielectric cooling fluid is a dielectric liquid with Prandtl number above 50 in a temperature range of operation of the electric component.

13. A method of controlling a static electric induction system comprising a heat generating electric component, a dielectric cooling fluid, a cooling passage structure along the electric component, and a pump arrangement arranged to pump the dielectric cooling fluid, wherein the dielectric cooling fluid is a dielectric liquid with Prandtl number above 20 in a temperature range of operation of the electric component, and wherein the method comprises: controlling the pump arrangement in a first mode to pump the cooling fluid such that the dielectric cooling fluid is driven through the cooling passage structure in a forward direction to cool the electric component; and controlling the pump arrangement in a second mode to pump the cooling fluid such that the dielectric cooling fluid is driven through the cooling passage structure in a reverse direction, opposite to the forward direction, to cool the electric component.

14. The method according to claim 13, further comprising controlling the pump arrangement in the first mode during at least five minutes prior to controlling the pump arrangement in the second mode.

15. The method according to claim 13, wherein the static electric induction system further comprises an insulation material arranged to electrically insulate the electric component, and wherein the method further comprises: estimating a condition or an expected remaining lifetime of the insulation material; and switching the control of the pump arrangement between the first mode and the second mode based on the estimation.

16. The method according to claim 15 wherein estimating the condition or the expected remaining lifetime of the insulation material comprises estimating the condition or the expected remaining lifetime of the insulation material based on one or more of data from a monitoring system and data from a digital twin of the static electric induction system.

17. The method according to claim 13, wherein the static electric induction system includes a winding having a bottom part and a top part and the cooling passage structure is arranged along the winding from the bottom part to the top part, and controlling the pump arrangement in the first mode to pump the cooling fluid such that the dielectric cooling fluid is driven through the cooling passage structure in the forward direction to cool the electric component comprises controlling the pump arrangement in the first mode to pump the cooling fluid from the bottom part, through the cooling passage structure, and to the top part.

18. The method according to claim 13, wherein the static electric induction system includes a winding having a bottom part and a top part and the cooling passage structure is arranged along the winding from the bottom part to the top part, and controlling the pump arrangement in the second mode to pump the cooling fluid such that the dielectric cooling fluid is driven through the cooling passage structure in a reverse direction to cool the electric component comprises controlling the pump arrangement in the first mode to pump the cooling fluid from the top part, through the cooling passage structure, and to the bottom part.

19. The method according to claim 13 wherein the static electric induction system further comprises a suction chamber arranged above the electric component, wherein the method further comprises sucking the dielectric cooling fluid from the cooling passage structure into the suction chamber when the pump arrangement is controlled in the first mode; and discharging the dielectric cooling fluid from the suction chamber into the cooling passage structure when the pump arrangement is controlled in the second mode

20. The static electric induction system according to claim 1, wherein the dielectric cooling fluid is a dielectric liquid with Prandtl number above 100 in a temperature range of operation of the electric component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Further details, advantages and aspects of the present disclosure will become apparent from the following embodiments taken in conjunction with the drawings, wherein:

[0058] FIG. 1 schematically represents a static electric induction system and a pump arrangement controlled in a first mode; and

[0059] FIG. 2 schematically represents the static electric induction system and the pump arrangement controlled in a second mode.

DETAILED DESCRIPTION

[0060] In the following, a static electric induction system comprising a pump arrangement arranged to pump cooling fluid through a cooling passage structure in a forward direction and in a reverse direction, and a method of controlling a static electric induction system comprising pumping cooling fluid through a cooling passage structure in a forward direction and in a reverse direction, will be described. The same or similar reference numerals will be used to denote the same or similar structural features.

[0061] FIG. 1 schematically represents a static electric induction system 10. The static electric induction system 10 of this example is a high voltage power transformer comprising an enclosure 12 filled with a dielectric cooling fluid 14. The static electric induction system 10 further comprises a low voltage winding 16, a high voltage winding 18 and a pump arrangement 20. The windings 16, 18 are arranged inside the enclosure 12 and the pump arrangement 20 is arranged outside the enclosure 12. The pump arrangement 20 of this example comprises a reversible pump 22.

[0062] A high voltage power transformer is used as an example, but the static electric induction system 10 of the present disclosure may alternatively be e.g. a reactor. The power transformer in FIG. 1 is a single-phase transformer, but the discussion is in applicable parts relevant for any type of transformer or other static electric induction system 10, e.g. a three-phase transformer such as with a three or five legged magnetic core. It should be noted that FIG. 1 is only schematic and provided to illustrate some basic parts of the static electric induction system 10.

[0063] The cooling fluid 14 is a dielectric liquid, such as a mineral oil, a natural ester, a synthetic ester or an isoparaffinic liquid. The cooling fluid 14 has a Prandtl number above 100 in a temperature range of operation of the static electric induction system 10.

[0064] Each winding 16, 18 comprises a plurality of cable turns 24 wrapped in an electrically insulated insulation material 26, such as paper. The cable turns 24 of each winding 16, 18 are wound around a magnetic core (not shown). Each cable turn 24 is a heat generating electric component during operation of the static electric induction system 10.

[0065] The cable turns 24 are arranged in discs 28. In FIG. 1, each winding 16, 18 comprises 12 discs 28, but the number of discs 28 and the number of cable turns 24 in each disc 28 may vary. Each winding 16, 18 further comprises an insulation cylinder 30. One or more horizontal spacers (not shown) may be arranged between the discs 28. One or more vertical spacers (not shown) may be arranged between the discs 28 and the insulation cylinder 30. Two pressboard barriers 32 are arranged between the windings 16, 18.

[0066] Each winding 16, 18 further comprises three washers 34. The washers 34 are alternatingly protruding horizontally from the insulation cylinder 30. The washers 34 define a plurality of winding sections. Each winding 16, 18 of this example thus comprises four winding sections and each winding section comprises three discs 28.

[0067] Each winding 16, 18 comprises a top part 36 and a bottom part 38. A top opening 40 is arranged in the top part 36 and a bottom opening 42 is arranged in the bottom part 38. The top opening 40 and the bottom opening 42 are at different heights and on vertically opposite sides of the respective winding 16, 18.

[0068] The static electric induction system 10 further comprises a cooling passage structure 44 through each winding 16, 18. Each cooling passage structure 44 extends between the top opening 40 and the bottom opening 42 through the entire respective winding 16, 18. Each cooling passage structure 44 thus extends over the entire height of the respective winding 16, 18.

[0069] In this example, each cooling passage structure 44 comprises two vertical sections 46 and a plurality of horizontal sections 48 between the vertical sections 46. By means of the cooling passage structures 44, the cooling fluid 14 can be led to and past the cable turns 24 to transport heat away from the cable turns 24 and the insulation material 26 to thereby cool the same.

[0070] The static electric induction system 10 further comprises a control system 50. The control system 50 comprises a data processing device 52 and a memory 54 having a computer program stored thereon. The computer program comprises program code which, when executed by the data processing device 52, causes the data processing device 52 to control operation of the pump arrangement 20.

[0071] The static electric induction system 10 further comprises a suction chamber 56. The suction chamber 56 is arranged inside the enclosure 12 above both windings 16, 18.

[0072] The static electric induction system 10 further comprises a cooler 58, for example a heat exchanger. The cooler 58 is arranged serially with the pump 22, in this example below the pump 22. Also the cooler 58 is arranged outside of the enclosure 12.

[0073] The static electric induction system 10 further comprises an upper passage 60 and a lower passage 62. The upper passage 60 of this example is a closed pipe structure arranged between the suction chamber 56 and the pump 22. To this end, the upper passage 60 extends through an upper opening 64 in the enclosure 12. Adjacent to the suction chamber 56, the upper passage 60 branches into two pipe sections. The lower passage 62 of this example is a pipe arranged between the cooler 58 and a bottom section 66 of the enclosure 12. The lower passage 62 extends through a lower opening 68 in the enclosure 12.

[0074] The enclosure 12 further comprises a side section 70 laterally outside the windings 16, 18 and a top section 72 above the suction chamber 56. The side section 70 and the top section 72 also contain cooling fluid 14 and are in fluid communication with the bottom section 66.

[0075] In the example in FIG. 1, the pump 22, the cooler 58, the lower passage 62, the bottom section 66, the cooling passage structures 44 through the windings 16, 18, the suction chamber 56 and the upper passage 60 form a cooling circuit.

[0076] In FIG. 1, the pump arrangement 20 is controlled in a first mode 74. This causes the cooling fluid 14 to be forced through the cooling passage structure 44 in a forward direction 76 to cool the cable turns 24. As shown in FIG. 1, cool cooling fluid 14, that has accumulated in the bottom part 38, is sucked directly into the cooling passage structure 44 through the bottom opening 42. The cooling fluid 14 flows from the bottom part 38 to the top part 36 of each winding 16, 18 when the pump 22 is controlled in the first mode 74.

[0077] In the first mode 74, the bottom opening 42 constitutes an inlet and the top opening 40 constitutes an outlet. Furthermore, in the first mode 74, the cooling fluid 14 flows upwards in each vertical section 46. Thus, the cooling fluid 14 flows generally upwards through the windings 16, 18.

[0078] In this example, the pump 22 is controlled to pump the cooling fluid 14 downwards from the pump 22 through the cooler 58. Thus, the pump 22 cooperates with gravity in the first mode 74. This causes the suction chamber 56 to suck cooling fluid 14 through the cooling passage structure 44 to cool the cable turns 24. The suction chamber 56 may also suck some bypassed cooling fluid 14 directly from the side section 70. Due to the Venturi effect, one or more hotspots 78 may in this case be formed in a lower part of one or several winding sections.

[0079] The ageing of the insulation material 26 largely depends on the time integrated value of the local temperature adjacent to the insulation material 26. If the hotspot 78 is maintained in the position shown in FIG. 1, the insulation material 26 adjacent to the hotspot 78 will eventually be subjected to higher temperatures and consequently a faster ageing. The lifetime of the static electric induction system 10 will consequently be shortened.

[0080] FIG. 2 schematically represents the static electric induction system 10. In FIG. 2, the pump 22 is controlled in a second mode 80. Under the control of the control system 50, the pump 22 can be alternatingly controlled in the first mode 74 and in the second mode 80, for example during time intervals of approximately ten minutes.

[0081] When the pump 22 is controlled in the second mode 80, the cooling fluid 14 is forced through the cooling passage structure 44 in a reverse direction 82, opposite to the forward direction 76, to cool the cable turns 24. Thus, the second mode 80 is distinct from the first mode 74. As shown in FIG. 2, the cooling fluid 14 flows from the top part 36 to the bottom part 38 of each winding 16, 18 when the pump 22 is controlled in the second mode 80.

[0082] In the second mode 80, the top opening 40 constitutes an inlet and the bottom opening 42 constitutes an outlet. Furthermore, in the second mode 80, the cooling fluid 14 flows downwards in each vertical section 46. Thus, the cooling fluid 14 flows generally downwards through the windings 16, 18.

[0083] In this example, the pump 22 is controlled to pump the cooling fluid 14 upwards from the cooler 58 and into the upper passage 60. Thus, the pump 22 counteracts gravity in the second mode 80. This causes the suction chamber 56 to discharge cooling fluid 14 into the cooling passage structure 44 to cool the cable turns 24. After passing through the entire respective winding 16, 18, the cooling fluid 14 is discharged from the cooling passage structure 44 into the bottom section 66.

[0084] Due to the Venturi effect, one or more hotspots 78 may in this case be formed in an upper part of one or more winding sections, i.e. at different positions than in FIG. 1 when the pump 22 operates in the first mode 74. Thus, positions the hotspots 78 are different depending on whether the cooling fluid 14 passes through the cooling passage structure 44 in the forward direction 76 or in the reverse direction 82. As can be gathered from FIGS. 1 and 2, the temperature distributions in the windings 16, 18 due to hydrodynamic effects are substantially the opposite in the forward direction 76 and in the reverse direction 82.

[0085] By alternating the direction of cooling fluid 14 through the cooling passage structure 44 from time to time by changing the operating state of the pump arrangement 20 between the first mode 74 and the second mode 80, the position of one or more hotspots 78 can be changed. Averaged over time, the ageing of the insulation material 26 can thereby be reduced. Alternatively, the enclosure 12 can be made more compact.

[0086] In order to determine when to switch between the first mode 74 and the second mode 80, a condition or an expected remaining lifetime of the insulation material 26 can be taken into account. The estimation may for example be based on data from a monitoring system (not shown), such as temperature data, or from a digital twin (not shown) of the static electric induction system 10. Artificial intelligence, e.g. implemented in the control system 50, can be used to further optimize the alternations between the first mode 74 and the second mode 80 without the need for human supervision.

[0087] While the present disclosure has been described with reference to exemplary embodiments, it will be appreciated that the present subject matter is not limited to what has been described above. For example, it will be appreciated that the dimensions of the parts may be varied as needed. Accordingly, it is intended that the present subject matter may be limited only by the scope of the claims appended hereto.