US-12626857-B2 - Transformer arrangement

US12626857B2US 12626857 B2US12626857 B2US 12626857B2US-12626857-B2

Abstract

The disclosure relates to a transformer arrangement comprising a transformer which comprises at least one phase winding. The phase winding has coil turns around a coil axis. The transformer arrangement further comprises a transformer tank having walls forming an enclosure in which the transformer is arranged. The enclosure contains an incompressible medium in which the transformer is immersed. A screen is arranged in the transformer tank, between the walls of the transformer tank and the at least one phase winding of the transformer. The screen has an inner, transformer-facing, surface and an outer, wall-facing, surface. The transformer tank has a first wall extending transversely to a first axis adjacent to a first end of the transformer and an opposite second wall extending transversely to the first axis, adjacent to a second end of the transformer.

Inventors

Anders Daneryd
Kiran Chandra Sahu

Assignees

HITACHI ENERGY LTD

Dates

Publication Date: 20260512
Application Date: 20230131
Priority Date: 20220225

Claims (6)

1 . A transformer arrangement comprising: a transformer comprising at least one phase winding, said phase winding having coil turns around a coil axis, the transformer having a first extension along a first axis parallel with the coil axis, a second extension along a second axis and a third extension along a third axis, said first, second and third axes being perpendicular to each other, and the transformer having lateral sides parallel with the coil axis, a transformer tank having walls forming an enclosure in which said transformer is arranged, said enclosure containing an incompressible medium in which the transformer is immersed, a screen arranged in said transformer tank, between the walls of the transformer tank and the at least one phase winding of the transformer, said screen having an inner, transformer-facing, surface and an outer, wall-facing, surface, the screen being arranged distanced from the at least one phase winding of the transformer, and wherein the transformer has a first end along the first axis and an opposite second end along the first axis, and wherein the transformer tank has a first wall extending transversely to the first axis adjacent to the first end of the transformer and an opposite second wall extending transversely to the first axis, adjacent to the second end of the transformer, wherein the screen has at least one first part and at least one second part, each extending transversely to the first axis and wherein the at least one first part is arranged between the first end of the transformer and the first wall of the transformer tank and the at least one second part is arranged between the second end of the transformer and the second wall of the transformer tank, and wherein the screen has at least one lateral part aligned with the lateral sides of the transformer, and wherein the at least one lateral part of the screen comprises a continuous band that circumscribes the transformer, and wherein the screen is configured to be free from structural resonances at twice a network frequency, wherein the screen is arranged distanced from the walls of the transformer tank, wherein a distance between the inner, transformer-facing, surface of the at least one lateral part of the screen and a closest part of the at least one phase winding of the transformer is less than a distance between the inner, transformer-facing, surface of the at least one lateral part of the screen and a closest part of the walls of the transformer tank.
2 . The transformer arrangement according to claim 1 , wherein the screen is configured to be-free from structural resonances at twice the network frequency by being rigid, by comprising a volumetrically compressible lining, or by comprising a granular material.
3 . The transformer arrangement according to claim 1 , wherein the inner surface of the screen comprises a volumetrically compressible lining.
4 . The transformer arrangement according to claim 3 , wherein the lining has a bulk modulus≤1.7 GPa.
5 . The transformer arrangement according to claim 1 , wherein the screen comprises a granular material.
6 . The transformer arrangement according to claim 5 , wherein the granular material has a density of more than 870 kg/m3, or more preferably a density of more than 1600 kg/m3.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a 35 U.S.C. § 371 national stage application of PCT International Application No. PCT/EP2023/052252 filed on Jan. 31, 2023, which in turn claims priority to European Patent Application No. 22158980.7, filed on Feb. 25, 2022, the disclosures and content of which are incorporated by reference herein in their entireties. TECHNICAL FIELD The present disclosure relates to a transformer arrangement for load-noise reduction. BACKGROUND Transformers must comply with various requirements on noise levels. Transformers immersed in electrically insulating oil in transformer tanks vibrate during operation. The vibrations are transferred from the transformer windings, via the oil, to the tank walls, which can lead to significant vibrational displacement of the tank walls, which in turn results in generation of noise. Three main sources of noise can be identified in transformers: no-load noise, or core noise, generated by magnetostriction, load noise produced by electromagnetic forces in the windings, and noise due to auxiliary equipment such as fans and pumps used in the cooling system. Out of these three, load noise has significant contribution to the total noise, especially for large units. Today's solutions to reduce noise are inefficient and costly and are being applied far away from the source and primary transmission path of load noise. The conventional solutions are often also bulky and impractical, such as sound panels and damping layers attached to the outside of the tank walls. Filling tank structural elements with sand is another low noise solution, but primarily for core noise, and with limited effect on load noise. Conventional solutions are difficult to optimize and standardize for off-the-shelf everyday design work because of the complex vibration/radiation properties of transformer tanks in which the transformers are enclosed. Sometimes there are also significant unit-to-unit variations. According to its abstract, WO0101425 relates to a sound-insulating device for a stationary induction machine with an active part, an insulating fluid surrounding the active part, and a tank enclosing the insulating fluid. The sound-absorbing device comprises a gas-filled cavity and a resilient membrane surrounding the gas-filled cavity, thus obtaining a sound-insulating device which is extremely compressible. In the induction machine, the device is arranged between the active part and the tank of the induction machine and spaced from the inside of the tank. The sound-insulating device may have an extent in one plane, whereby the device has a membrane portion facing the active part and a membrane portion facing the tank. In some embodiments, at least one of the membrane portions has at least one corrugated region, and a spacing membrane is arranged in the cavity making contact with the membrane portion at least two points. According to its abstract, JPH10106854 relates to stationary induction electrical equipment which can reduce noise even when the constitution of the equipment is made compact. A resonance type silencer which has a partly formed opening an internal cavity is provided on the internal surface of a tank. Since the silencer is set at the frequency which resonates to the frequency of noise produced in the tank, the silencer can reduce the noise produced in the tank by resonating to the frequency of the noise. Therefore, the noise radiated to the outside from the tank can be reduced. According to its abstract, CN201732653 relates to a sound-proof oil tank structure of a transformer, comprising an oil tank body, wherein the inner wall of the oil tank body is provided with a composite damping steel plate; when the inner wall of the oil tank body is provided with a magnetic shield, the inner side and the outer side of the magnetic shield are respectively provided with two layers of composite damping steel plates which are pressed tightly by clamping plates of the magnetic shield; and when the inner wall of the oil tank body is not provided with the magnetic shield, the composite damping steel plates are fixed by installation seats at the inner wall of the oil tank body. By arranging the composite damping steel plates at the inner wall of the oil tank body of the transformer, the noise of the transformer body is effectively reduced. The sound-proof oil tank structure of the transformer has simple structure, and convenience in manufacture and installation. According to its abstract, CN105810419 relates to a noise reduction apparatus for a transformer, a transformer oil tank and the transformer. The noise reduction apparatus comprises a noise reduction plate, and an insulating layer for covering the surface of the noise reduction plate, wherein the noise reduction plate comprises at least two paperboard layers, and a metal plate layer arranged between adjacent paperboard layers; and in addition, the topmost layer and the lowest layer of the noise reduction p