Three-phase generator transformer with super-large capacity

Abstract

The invention discloses a three-phase generator transformer with super-large capacity, which comprises an iron core, a low-voltage coil and a high-voltage coil and is characterized in that the low-voltage coil is divided into a first low-voltage coil branch and a second low-voltage coil branch which are connected in series, and the number of turns of the first low-voltage coil branch is equal to the number of turns of the second low-voltage coil branch; the iron core, the first low-voltage coil branch, the second low-voltage coil branch and the high-voltage coil are sequentially arranged fromthe inside to the outside; the two series branches namely the first low-voltage coil branch and the second low-voltage coil branch of the low-voltage coil are respectively in a double-layer multi-spiral structure formed by integrally winding self-adhesive transposed conductors; and the first low-voltage coil branch and the second low-voltage coil branch are separated by an oil clearance brace andan insulating cylinder. The invention not only can obviously lower the transport height of the transformer but also can well solve the problem of magnetic leakage inhibition of low-voltage super-large current leads, thereby improving the economy and the practicability of the three-phase generator transformer with super-large capacity.

Description

technical field [0001] The invention belongs to the field of transformers and relates to a super-large-capacity three-phase generator transformer. Background technique [0002] The industry standard DL-5000-2000 "Technical Regulations for Design of Thermal Power Plants" stipulates: "If the main transformer connected to the unit with a capacity of 300MW or below is not restricted by transportation conditions, a three-phase transformer should be selected. And the capacity For the main transformer connected to the 600MW generating unit, single-phase or three-phase transformers should be selected based on comprehensive transportation and manufacturing conditions, after economic and technical comparison.” For transformers of 370MVA and above that are matched with 300MW generating sets, we usually call them "Extra Large Capacity Generator Transformer". [0003] Compared with the three-phase transformer group composed of single-phase transformers, the ultra-large-capacity generato...

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Problems solved by technology

[0008] ⑤ When there is a three-phase imbalance in the actual operation of the single-phase transformer, magnetic oscillation may occur, which may cause accidents;

[0012] In addition, when the ultra-large-capacity generator transformer adopts a three-phase integrated structure, since the capacity of this transformer often reaches 370MVA and above, while the output voltage of the low-voltage side, that is, the generator side, is generally about 20 kV, and its current reaches tens of thousands Ampere; The connection method of the low-voltage side is usually a delta connection method, and it is necessary to connect the ends of the low-voltage coil to the low-voltage bushing rising seat on the upper part of the fuel tank; when the conventional coil arrangement structure (such as the attached figure 2 As shown), the end B of the low-voltage coil protrudes from the lower part of the coil. When the copper tube or copper bar is connected to the low-voltage rising seat on the upper part of the fuel tank, such a huge current-carrying conductor will produce non-negligible leakage in the area it passes through. The magnetic effect will generate additional stray loss up to tens of kilowatts in the adjacent steel structure and cause obvious heating of the structure. In order to suppress this additional loss or overheating, it is necessary to use a large area of ​​low magnetic steel plate, add Measures such as thick magnetic shielding or increasing the distance between the lead wire and the oil tank, but these measures are not effective and will significantly increase the manufacturing cost of the three-phase transformer

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