EP-4740230-A1 - TRANSFORMER ARRANGEMENT HAVING AN AIR DUCT ELEMENT, AIR DUCT ELEMENT, AND COOLING SYSTEM FOR COOLING A TRANSFORMER

Abstract

The invention relates to an air duct element which is configured to be attached to a fan air outlet of a fan for cooling a dry-type transformer. The air duct element is configured to divide an airflow generated by the fan and delivered through the fan air outlet into at least a first airflow portion and a second airflow portion. The air duct element is configured to direct the first airflow portion and the second airflow portion to different individual parts of the transformer. The air duct element comprises a first airflow portion opening for outlet of the first airflow portion. The first airflow portion opening has two opposing edge regions which are at least partially curved in an identical direction. The invention further relates to a cooling system comprising an air duct element, and to a dry-type transformer.

Inventors

• DE LA VEGA-HAZAS ALVAREZ-BARON, Alfredo
• NOGUES BARRIERAS, ANTONIO
• ROY MARTIN, Carlos Manuel
• Cebrian Lles, Lorena
• MAORAD VIDEGAIN, Juan
• MURILLO JASO, Rafael
• MUNOZ ARRIBAS, Fernando
• MURGIDA, Vito
• DIAZ MEZA, Dario Martin

Assignees

• Hitachi Energy Ltd

Dates

Publication Date

20260513

Application Date

20240704

Claims (13)

1. 1. A transformer arrangement, comprising a transformer core (50), defining a longitudinal axis (L), a coil assembly wound around the core (50), the coil assembly comprising a winding (60, 70), and an air duct element (2) configured and arranged to direct an airflow portion (62, 64, 66) to a bottom end (69, 79) of the winding (60, 70) and/or along an inner or outer surface area (72, 74; 65, 67) of the winding (60, 70) for cooling the coil assembly and/or the core (50), wherein the air duct element (2) comprises a first flow channel inlet opening (110), a first flow channel outlet opening (10), a first flow channel (210) extending from the first flow channel inlet opening (110) to the first flow channel outlet opening (10), thereby defining a first longitudinal centerline (Cl), a second flow channel inlet opening (120), a second flow channel outlet opening (20), a second flow channel (220) extending from the second flow channel inlet opening (120) to the second flow channel outlet opening (20), thereby defining a second longitudinal centerline (C2), wherein the cross-sectional areas of the first flow channel (210) normal to the first centerline (Cl) and/or the cross-sectional areas of the second flow channel (220) normal to the second centerline (C2) change continuously at least along the majority of the length of the respective flow channel (210, 220).
2. 2. The arrangement of claim 1, wherein a distance (6) between the air duct element (2) and the bottom end (69, 79) of the winding (60, 70) is less than 50 mm.
3. 3. The arrangement of the preceding claims, wherein the majority of the length of the respective flow channel (210, 220) is at least 55%, preferably at least 60%, preferably at least 70 %, preferably at least 80 %, preferably at least 90 %, preferably at least 95 %, preferably at least 98% of the length of the flow channel.
4. 4. The arrangement of any of the preceding claims, wherein the first flow channel outlet opening (10) has a cross-sectional area normal to the first centerline (Cl) which differs by at least 3% from a cross-sectional area of the first flow channel inlet opening (110) normal to the first centerline (Cl), and/or wherein the second flow channel outlet opening (20) has a cross-sectional area normal to the second centerline (C2) which differs by at least 3% from a cross-sectional area of the second flow channel inlet opening (120) normal to the second centerline (C2), and/or wherein the first flow channel outlet opening (10) has a cross-sectional area normal to the first centerline (Cl) which differs by at most 100% from a cross-sectional area of the first flow channel inlet opening (110) normal to the first centerline (Cl), and/or wherein the second flow channel outlet opening (20) has a cross-sectional area normal to the second centerline (C2) which differs by at most 100% from a cross-sectional area of the second flow channel inlet opening (120) normal to the second centerline (C2).
5. 5. The arrangement of any of the preceding claims, wherein the first centerline (Cl) and/or the second centerline (C2) comprises a curved section, preferably wherein the curved section extends over more than 50% of the total length of the respective centerline (Cl, C2), preferably over more than 60%, preferably over more than 70%, preferably over more than 80%, preferably over more than 90%.
6. 6. The arrangement of any of the preceding claims, wherein the first flow channel inlet opening (110) and the second flow channel inlet opening (120) constitute parts of an inlet opening (22) of the air duct element (2).
7. 7. The arrangement of any of the preceding claims, wherein the airduct element (2) is made from a dielectrical material and/or a non- conductive material; and/or wherein the air duct element (2) is manufactured by additive manufacturing.
8. 8. The arrangement of any of the preceding claims, further comprising a fan (4) having a fan air outlet (42), the fan (4) being configured and arranged to generate an airflow (6) and to deliver the airflow (6) through the fan air outlet (42) to an air inlet opening (22) of the air duct element (2), preferably wherein inner surfaces of the air duct element (2) for guiding the airflow (6) from the air inlet opening (22) to at least one of the first flow channel outlet opening (10) and the second flow channel outlet opening (20) are smooth and without steps or sharp edges.
9. 9. An air duct element (2), configured to direct an airflow portion (62, 64, 66) to an outer or inner edge of a bottom end (69, 79) of a winding (60, 70) of a coil assembly of a transformer and/or along an inner or outer surface area (72, 74, 65, 67) of a winding (60, 70) of a coil assembly of a transformer and/or to at least one cooling gap provided in the transformer arrangement, wherein the air duct element (2) comprises a first flow channel inlet opening (110), a first flow channel outlet opening (10), a first flow channel (210) extending from the first flow channel inlet opening (110) to the first flow channel outlet opening (10), thereby defining a first longitudinal centerline (Cl), a second flow channel inlet opening (120), a second flow channel outlet opening (20), a second flow channel (220) extending from the second flow channel inlet opening (120) to the second flow channel outlet opening (20), thereby defining a second longitudinal centerline (C2), wherein the cross-sectional areas of the first flow channel (210) normal to the first centerline (Cl) and/or the cross-sectional areas of the second flow channel (220) normal to the second centerline (C2) change continuously at least along the majority of the length of the respective flow channel (210, 220).
10. 10. The air duct element (2) of claim 9, wherein the majority of the length of the respective flow channel (210, 220) is at least 55%, preferably at least 60%, preferably at least 70 %, preferably at least 80 %, preferably at least 90 %, preferably at least 95 %, preferably at least 98%.
11. 11. The air duct element (2) of 9 or 10, wherein the first flow channel outlet opening (10) has a cross-sectional area normal to the first centerline (Cl) which differs by at least 3% from a cross-sectional area of the first flow channel inlet opening (110) normal to the first centerline (Cl), and/or wherein the second flow channel outlet opening (20) has a cross-sectional area normal to the second centerline (C2) which differs by at least 3% from a cross-sectional area of the second flow channel inlet opening (120) normal to the second centerline (C2), and/or wherein the first flow channel outlet opening (10) has a cross-sectional area normal to the first centerline (Cl) which differs by at most 100% from a cross-sectional area of the first flow channel inlet opening (110) normal to the first centerline (Cl), and/or wherein the second flow channel outlet opening (20) has a cross-sectional area normal to the second centerline (C2) which differs by at most 100% from a cross-sectional area of the second flow channel inlet opening (120) normal to the second centerline (C2).
12. 12. The air duct element (2) of any of claims 9 to 11, wherein the first centerline (Cl) and/or the second centerline (C2) comprises a curved section, preferably wherein the curved section extends over more than 50% of the total length of the respective centerline (Cl, C2), preferably over more than 60%, preferably over more than 70%, preferably over more than 80%, preferably over more than 90%.
13. 13. The air duct element (2) of any of claims 9 to 12, wherein the first flow channel inlet opening (110) and the second flow channel inlet opening (120) constitute parts of an inlet opening (22) of the air duct element (2).

Description

TRANSFORMER ARRANGEMENT HAVING AN AIR DUCT ELEMENT, AIR DUCT ELEMENT, AND COOLING SYSTEM FOR COOLING A TRANSFORMER BACKGROUND The present disclosure relates to a transformer arrangement comprising an air duct element for cooling a coil assembly and/or a core of the transformer arrangement, a respective air duct element, and a cooling system comprising such an air duct element. Transformers are used to convert electricity from a first voltage level to an electricity at a second voltage level which is either higher or a lower than the first voltage level. A typical transformer comprises two sets of insulated wire coils - herein also referred to as "windings" for short - around a ferromagnetic core of the transformer, namely a high voltage (HV) winding and low voltage (LV) winding. The LV winding often constitutes an inner winding, and the HV winding an outer winding. When electrical power is applied to one winding that draws power from a source of voltage, it is then magnetically transferred to another winding that delivers power to a load at a transformed voltage. The ratio of turns in one winding to the turns in another winding is the same as the ratio of the voltage of the source to the voltage of the load. In a dry-type transformer, typically used for power distribution networks, no dielectric liquid is used for insulating the windings. A dry-type transformer performance is principally highly limited by temperature rise during operation due to losses and heat dissipation. Presently, centrifugal fans with very high air-flow rate are typically used for air-forced cooling of a dry-type transformer. Fig. 1 schematically shows a centrifugal fan 200 positioned in a lower region of a transformer. The transformer comprises a core 500, an inner winding 600, and an outer winding 700. Heat-producing parts of the transformer are primarily its windings and the core. The centrifugal fan 200 generates an airflow 800 directed at the windings 600, 700 and the core 500. However, a problem here is that much of the air expelled by the centrifugal fan 200 does not specifically reach those parts of the transformer whose cooling is particularly important. This results in an airflow waste and a reduced cooling efficiency. It is also known to use a fan and an air duct coupled to the fan to direct cooling air to a dry-type transformer. However, also here only limited efficiency can be achieved with the known solutions. Therefore, there is a need for a technology providing improved cooling of a transformer, particularly a dry-type transformer. SUMMARY According to the present invention, a transformer arrangement - also referred to here as a transformer for short - is provided which comprises a transformer core, defining a longitudinal axis, a coil assembly wound around the core, the coil assembly comprising a winding, and an air duct element configured and arranged to direct an airflow portion to a bottom end of the winding and/or along an inner or outer surface area of the winding and/or to at least one cooling gap provided in the transformer arrangement for cooling the coil assembly and/or the core. The longitudinal axis may coincide with a main axis of the coil assembly. A distance between the air duct element and the bottom end of the winding may be less than 50 mm. The air duct element allows for directing the airflow portion in a particular effective way to the bottom end of the winding and/or along the inner or outer surface area of the winding and/or at least one cooling gap for cooling the coil assembly and/or the core, i.e. to parts of the transformer arrangement whose cooling during operation of the transformer is of particular importance. In this way, an airflow waste or loss can be significantly reduced. The air duct element is particularly suited to be adapted or configured to deliver the airflow portion in a particularly precise manner to respective areas or parts of the transformer arrangement. Air can be substantially prevented from flowing to regions where it is not needed for the desired cooling effect. Moreover, the air duct element can be easily configured such that generation of turbulences is significantly reduced. Various embodiments may implement one or more of the following features: The air duct element may comprise a first flow channel inlet opening, a first flow channel outlet opening, a first flow channel extending from the first flow channel inlet opening to the first flow channel outlet opening, thereby defining a first longitudinal extension line. The air duct element may further comprise a second flow channel inlet opening, a second flow channel outlet opening, a second flow channel extending from the second flow channel inlet opening to the second flow channel outlet opening, thereby defining a second longitudinal extension line. The thickness or width of the first flow channel and/or the thickness or width of the second flow channel may change continuously at least along the majority of the