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KR-102964150-B1 - Cooling array for cooling a transformer

KR102964150B1KR 102964150 B1KR102964150 B1KR 102964150B1KR-102964150-B1

Abstract

The present invention relates to a cooling array (1) for cooling a transformer (10) in a transformer tank (12), wherein the cooling array (1) comprises a transformer tank (12) that is at least partially filled with an electrical insulating fluid when in use, a transformer (10) having windings (14), at least one heat exchanger (18), a fluid discharge device (20) arranged within the transformer tank (12) and fluidly connected to at least one heat exchanger (18), and a pump (22) fluidly communicating with at least one heat exchanger (18) and the fluid discharge device (20). The fluid discharge device (20) comprises at least one Coanda effect fluid flow amplifier (21) configured to discharge the cooled fluid along a discharge axis (c) toward one or more of the windings (16) of at least one phase leg (14) of the transformer (10).

Inventors

  • 산드 울프
  • 호사인 로크만
  • 살리나스 에네르
  • 프라드한 마노즈 쿠마르

Assignees

  • 히타치 에너지 리미티드

Dates

Publication Date
20260512
Application Date
20240216
Priority Date
20230217

Claims (15)

  1. As a cooling array (1) for cooling a transformer (10) in a transformer tank (12), the cooling array (1) is, - Transformer tank (12), which is at least partially filled with electrical insulating fluid when in use, - A transformer (10) comprising at least one phase leg (14), wherein the phase leg (14) has windings (16) arranged coaxially on a coil axis (a), and the transformer (10) is enclosed within the transformer tank (12) and at least partially immersed in the electrical insulating fluid, the transformer (10). - At least one heat exchanger (18) located outside the transformer tank (12), wherein the at least one heat exchanger (18) is fluidly connected to the transformer tank (12), and is configured to receive heated fluid from the transformer tank (12) and supply cooled fluid to the transformer tank (12); - A fluid discharge device (20) arranged within the transformer tank (12) and fluidly connected to the at least one heat exchanger (18) to receive a fluid cooled from the at least one heat exchanger (18) and discharge the cooled fluid into the transformer tank (12); and - A pump (22) configured to be in fluid communication with at least one heat exchanger (18) and the fluid discharge device (20) and to pump cooled fluid from the at least one heat exchanger (18) to the fluid discharge device (20). Includes, The above fluid discharge device (20) includes at least one Coanda effect fluid flow amplifier (21) configured to discharge the cooled fluid along the discharge axis (c) toward one or more of the windings (16) of the at least one phase leg (14) of the transformer (10), and Each of the above at least one fluid flow amplifier (21) forms a loop (24) around the discharge axis (c), and at least one of the loops (24) includes a fluid outlet (26) configured to discharge fluid along the discharge axis (c). A cooling array (1) characterized by fluid conduits (34) arranged to provide individually predetermined fluid flow from the outlet (26) of at least one fluid flow amplifier (21).
  2. In claim 1, the fluid discharge device (20) is a cooling array (1) arranged at a distance from the transformer (10).
  3. delete
  4. In claim 1, the fluid outlet (26) comprises at least one slit (28) extending around the discharge axis (c), forming a cooling array (1).
  5. In claim 1 or 4, the cooling array (1) is configured such that the loop (24) is accompanied by a fluid surrounding the loop (24) during the discharge of the fluid.
  6. In claim 1 or 4, the fluid outlet (26) is arranged to discharge fluid along at least one curved wall portion (27) of the loop (24) to accompany fluid by the Coanda effect along the discharge axis (c), a cooling array (1).
  7. In claim 1 or 4, the at least one fluid flow amplifier is a cooling array (1) arranged coaxially with the windings (16) such that the discharge axis (c) is aligned with the coil axis (a) and the fluid discharge device (20) is arranged to discharge fluid along the coil axis (a) toward the end (28) of the windings (16).
  8. In claim 7, adjacent coaxially arranged windings (16a, 16b) of the at least one phase leg (14) are separated from each other by at least one gap (30), and the loop (24) of the at least one fluid flow amplifier (21) is aligned with the at least one gap (30) to inject fluid into the gap (30) during fluid discharge, a cooling array (1).
  9. As a cooling array (1) for cooling a transformer (10) in a transformer tank (12), the cooling array (1) is, - Transformer tank (12), which is at least partially filled with electrical insulating fluid when in use, - A transformer (10) comprising at least one phase leg (14), wherein the phase leg (14) has windings (16) arranged coaxially on a coil axis (a), and the transformer (10) is enclosed within the transformer tank (12) and at least partially immersed in the electrical insulating fluid, the transformer (10). - At least one heat exchanger (18) located outside the transformer tank (12), wherein the at least one heat exchanger (18) is fluidly connected to the transformer tank (12), and is configured to receive heated fluid from the transformer tank (12) and supply cooled fluid to the transformer tank (12); - A fluid discharge device (20) arranged within the transformer tank (12) and fluidly connected to the at least one heat exchanger (18) to receive a fluid cooled from the at least one heat exchanger (18) and discharge the cooled fluid into the transformer tank (12); and - A pump (22) configured to be in fluid communication with at least one heat exchanger (18) and the fluid discharge device (20) and to pump cooled fluid from the at least one heat exchanger (18) to the fluid discharge device (20). Includes, The above fluid discharge device (20) includes at least one Coanda effect fluid flow amplifier (21) configured to discharge the cooled fluid along the discharge axis (c) toward one or more of the windings (16) of the at least one phase leg (14) of the transformer (10), and Each of the above at least one fluid flow amplifier (21) forms a loop (24) around the discharge axis (c), and at least one of the loops (24) includes a fluid outlet (26) configured to discharge fluid along the discharge axis (c). The above at least one fluid flow amplifier is arranged coaxially with the windings (16) such that the discharge axis (c) is aligned with the coil axis (a) and the fluid discharge device (20) is arranged to discharge fluid along the coil axis (a) toward the end (28) of the windings (16). A cooling array (1), wherein adjacent coaxially arranged windings (16a, 16b, 16c) of at least one phase leg (14) comprise a plurality of gaps (30a, 30b), the windings (16a, 16b, 16c) are separated from each other by the plurality of gaps (30a, 30b), and the fluid discharge device (20) comprises a plurality of fluid flow amplifiers (21a, 21b), each comprising a loop (24) around the discharge axis (c), and the loop (24) of each fluid flow amplifier (21a, 21b) is aligned with each coaxial gap (30a, 30b) to inject fluid into the gaps (30a, 30b) during fluid discharge.
  10. A cooling array (1), wherein, in claim 1 or 4, the transformer tank (12) has a tank bottom (32) during use, the transformer (10) is arranged vertically above the tank bottom (32), and the fluid discharge device (20) is arranged to accompany the fluid from the tank bottom (32) during fluid discharge.
  11. In any one of claims 1, 2 and 4, the transformer (10) comprises a plurality of phase legs (14a, 14b, 14c), and the cooling array (1) comprises a plurality of fluid discharge devices (20a, 20b, 20c), wherein the discharge axis (c) of each fluid discharge device (20a, 20b, 20c) is aligned with the respective coil axis (a) of each phase leg (14a, 14b, 14c), and the cooling array (1) is arranged such that each fluid discharge device (20a, 20b, 20c) discharges the cooled fluid toward the windings (16) of each phase leg (14) of the transformer (10).
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  13. In claim 1, the fluid conduit (34) is a cooling array (1) that is dimensioned to provide a predetermined fluid flow from the fluid flow amplifier (21) to which the fluid conduit (34) is fluidly connected.
  14. A cooling array (1) according to claim 1, further comprising a control unit (36) connected to a controllable valve (38), wherein the control unit (36) is configured to control the controllable valve (38) to provide a predetermined fluid flow from the outlet (26) of a fluid flow amplifier (21) of at least one fluid discharge device (20).
  15. In claim 14, the cooling array (1) is provided with at least one temperature sensor (40) that is communicably connected to the control unit (36) in the at least one phase leg (14), and the predetermined fluid flow is set according to the temperature measurement of the at least one temperature sensor (40).

Description

Cooling array for cooling a transformer The present invention relates to a cooling array for cooling a transformer. In particular, the present invention relates to a cooling array comprising a fluid discharge device including a fluid flow amplifier directed toward one or more windings of a transformer. Transformers carry high currents and can generate heat, which consequently results in heat loss. For the normal operation of a transformer, this heat must be dissipated into the surroundings. Transformers can be housed in transformer tanks filled with an electrical insulating fluid, such as oil, into which the transformer is immersed. The insulating fluid can also serve as a cooling medium. Most oil cooling is achieved by arranging external devices, such as heat exchangers, radiators, and coolers, through which the transformer oil circulates and cools. Due to natural convection within the transformer tank, and also in the case of forced convection of the oil, a temperature profile is established for the oil, and the temperature increases from the bottom to the top of the transformer tank and along the transformer windings, as shown in Fig. 1. The oil temperature establishes a boundary condition for the winding temperature. Therefore, the windings also follow a similar profile from the bottom to the top of the windings. However, some local temperature variations also exist. The windings, particularly at the ends of the windings, generate radial flux density fluctuations that produce radial eddy current losses. With the fluid being relatively hotter at the top of the windings, these radial eddy current losses can lead to hotspot problems, namely locally higher temperatures in the upper parts of the windings. Therefore, it is necessary to change the oil temperature profile so that the winding temperature and hot spot temperature can be reduced. Further objects, advantages, and features of the present invention will become apparent from the following description of one or more embodiments with reference to the accompanying drawings. Figure 1 illustrates examples of temperatures in prior art transformer arrays. FIG. 2 illustrates examples of temperatures in a transformer array including a cooling array according to a first embodiment of the present invention. FIG. 3 illustrates a schematic example of the configuration of a cooling array according to a first embodiment of the present invention. FIG. 4 illustrates another schematic example of the configuration of a cooling array according to the first embodiment of the present invention. FIG. 5 shows a plan view of a fluid discharge device of a first embodiment of the present invention. Figure 6 shows a side cross-sectional view of the fluid discharge device of Figure 5. Figure 7 shows a side cross-sectional view of the fluid discharge device of Figure 5. FIG. 8 illustrates an exemplary arrangement of a fluid discharge device having a phase leg of a transformer. FIG. 9 illustrates an exemplary arrangement of a fluid discharge device including two fluid flow amplifiers. FIG. 10 illustrates an exemplary arrangement of multi-phase legs arranged with fluid discharge devices. FIG. 11 illustrates an exemplary array of fluid flow amplifiers fluidly connected by fluid conduits. FIG. 12 illustrates an exemplary array of fluid flow amplifiers fluidly connected by fluid conduits. The present invention is further elaborated below with reference to the accompanying drawings illustrating examples of embodiments. The present invention should not be construed as being limited to the described examples of embodiments. Throughout the description, the same numbers refer to the same elements. The terms used herein are intended solely to describe specific aspects of the present disclosure and are not intended to limit the invention. The singular forms “one,” “one,” and “above” used herein are intended to include the plural forms as well, unless the context explicitly indicates otherwise. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art to which the present disclosure pertains. As discussed in the background section above, transformers can be housed in transformer tanks filled with an electrical insulating fluid, such as oil, into which the transformers are immersed. The insulating fluid can also serve as a cooling medium. Most cooling is performed by arranging external devices, such as heat exchangers, radiators, and coolers, in which the fluid circulates and cools. Due to natural convection within the transformer tank, and also in the case of forced convection of the fluid, a temperature profile is established for the oil, and the temperature increases from the bottom to the top of the transformer tank and along the transformer windings, as illustrated in the prior art example of Fig. 1, which exemplifies temperatures in prior art transformer arrays. The figure illustrate