CN211239345U

CN211239345U - Universal converter transformer suitable for +/-500 KV converter station

Info

Publication number: CN211239345U
Application number: CN202020115226.7U
Authority: CN
Inventors: 包维瀚; 姚大伟; 程青; 汲亚娟
Original assignee: Sichuan Energy Internet Research Institute EIRI Tsinghua University
Current assignee: Sichuan Energy Internet Research Institute EIRI Tsinghua University
Priority date: 2020-01-17
Filing date: 2020-01-17
Publication date: 2020-08-11
Anticipated expiration: 2030-01-17

Abstract

The utility model discloses a universal converter transformer suitable for a +/-500 KV converter station, which comprises three Y-shaped single-phase double-winding converter transformers and three D-shaped single-phase double-winding converter transformers, the converter valve side winding of the first Y-type single-phase double-winding converter transformer and the converter valve side winding of the first D-type single-phase double-winding converter transformer are connected in series to form a first winding, the converter valve side winding of the second Y-type single-phase double-winding converter transformer and the converter valve side winding of the second D-type single-phase double-winding converter transformer are connected in series to form a second winding, the converter valve side winding of the third Y-type single-phase double-winding converter transformer and the converter valve side winding of the third D-type single-phase double-winding converter transformer are connected in series to form a third winding, and the first winding, the second winding and the third winding are connected to form a Y-type topological structure. The utility model discloses reform transform into YnY wiring with converter transformer, solved the problem of high pressure overline, reduced valve room load.

Description

Universal converter transformer suitable for +/-500 KV converter station

Technical Field

The utility model relates to a converter transformer technical field especially relates to a general converter transformer suitable for 500KV current conversion station.

Background

The conventional high-voltage direct-current transmission project mostly adopts an LCC-HVDC (high-voltage direct current for power grid commutation) technical route, and the requirement on the short-circuit capacity of an alternating-current transmission network is higher and higher. If the alternating current transmission network is not upgraded and modified, the inverter station of the conventional high-voltage direct current transmission system inevitably has more and more phase conversion failures, and serious harm is brought to the stability of the local alternating current transmission network. At present, most of inversion ends of a direct current converter station are connected with a 500kV power grid, and the cost of upgrading and transforming an alternating current power grid of the voltage class is high, so that a conventional direct current inversion station is transformed, and a VSC-HVDC (flexible direct current transmission technology) adopted in the inversion station is an effective and economic choice.

Patent document CN109391157A discloses a general converter transformer for high voltage dc transmission system, and specifically discloses a scheme for transforming a common converter transformer into a YnD converter transformer (i.e. the converter transformer adopts a net-side star-grounded connection method and a valve-side delta connection method), the arrangement of the valve hall after transformation is as shown in fig. 1, as can be seen from fig. 1, in the scheme, in the engineering arrangement, since the valve side of the YnD transformer is connected into a delta, it is inevitable that one high voltage wire needs to cross all transformers, which may cause two problems: 1. increasing the load of the valve hall (the high-voltage wire needs to be hung on a valve hall roof truss by an insulator); 2. increasing the difficulty of construction and maintenance.

For a conventional dc converter station with voltage class of ± 500kV, there is only one valve hall for each pole, and a 12-pulse converter is used, so that a flexible dc converter with a pseudo-bipolar connection created by punching the valve hall for each pole can be considered.

SUMMERY OF THE UTILITY MODEL

In order to solve the above problem, the utility model provides a general converter transformer suitable for 500KV current conversion station: under the condition that the voltage grade of a system on the alternating current side and the direct current side is not changed, two groups of converter transformers of YnD wiring and YnY wiring of each pole of a conventional direct current system are transformed into a group of YnY converter transformers, so that the converter transformers are suitable for a flexible direct current system adopting a pseudo bipolar wiring, and the transformed two-pole system can jointly form a true bipolar system through a grounding mode on the direct current side. The utility model discloses need not change converter transformer inner structure, the outside electrical connection of accessible realizes, and the engineering scene implements simply.

Specifically, the utility model provides a general converter transformer suitable for 500KV converter station, including three Y type single-phase double-winding converter transformers and three D type single-phase double-winding converter transformers, the converter valve side winding of the first Y type single-phase double-winding converter transformer and the converter valve side winding of the first D type single-phase double-winding converter transformer are connected in series to form the first winding, thereby ensure that the insulation level of the two converter valve side windings does not need to change, in the same way, the converter valve side winding of the second Y type single-phase double-winding converter transformer and the converter valve side winding of the second D type single-phase double-winding converter transformer are connected in series to form the second winding, the converter valve side winding of the third Y type single-phase double-winding converter transformer and the converter valve side winding of the third D type single-phase double-winding converter transformer are connected in series to form the third winding, the first winding, the second winding and the third winding are connected to form a Y-shaped topological structure. The utility model provides a this general converter transformer, the change of current becomes the wiring convenient, does not need increase insulation distance.

Further, converter valve side windings of the D-type single-phase double-winding converter transformer in the first winding, the second winding and the third winding are connected to form a Y-type topological structure.

Further, the ac power grid side windings of the three Y-type single-phase double-winding converter transformers and the three D-type single-phase double-winding converter transformers are respectively incorporated into an ac power grid.

The beneficial effects of the utility model reside in that:

(1) the utility model discloses every utmost point YnD wiring of conventional direct current system and YnY wiring's two sets of converter transformers, reformed transform into a set of YnY converter transformers to be applicable to the flexible direct current system that adopts pseudo-bipolar wiring, through the ground connection mode of direct current side, two pole systems after the transformation can constitute true bipolar system jointly, need not change converter transformer inner structure, can realize through outside electrical connection, and the engineering scene is implemented simply;

(2) the utility model discloses to the current conversion station of 500kV grade and only single converter in every utmost point, reform transform into YnY wiring, solved the problem of high-pressure overline, reduced valve room load to and the degree of difficulty of construction and maintenance;

(3) the investment of the converter transformer accounts for half of the total investment of the equipment of the converter station, the utility model improves the wiring and the arrangement on the basis of the original converter transformer, and greatly saves the investment of engineering modification;

(4) the utility model discloses make full use of conventional direct current converter transformer can bear the characteristic of alternating current-direct current stack voltage simultaneously, combine its with the demand nature of the flexible direct current converter station of real bipolar wiring, satisfied the operation needs of flexible direct current converter station.

Drawings

Fig. 1 is a layout diagram of a valve hall in a prior converter transformer modification scheme;

FIG. 2 is a schematic diagram of a conventional DC converter transformer configuration of a +/-500 kV converter station;

FIG. 3 is a schematic diagram of a conventional DC converter transformer winding connection;

FIG. 4 is a wiring diagram of a valve side bushing of a conventional DC converter transformer;

fig. 5 is a schematic diagram of a converter transformer connection group according to the present invention;

fig. 6 is a valve side bushing wiring diagram of the converter transformer of the present invention.

Detailed Description

In order to clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will be described with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention, i.e., the described embodiments are only some, but not all embodiments of the invention. The components of embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiment of the present invention, all other embodiments obtained by the person skilled in the art without creative work belong to the protection scope of the present invention.

In a conventional dc converter station with ± 500kV class, two sets of transformers are required to be used in a total station for a two-pole converter, and the connection modes of the two sets of transformers are YnD and YnY, respectively, where YnD is a transformer grid side star ground connection and a valve side delta connection, and YnY is a transformer grid side star ground connection and a valve side delta connection. The power grid sides of the two groups of transformers are connected with an alternating current system in parallel, the converter valve sides are connected with two six-pulse valve groups respectively, and the six-pulse valve groups have the serial connection property in the aspect of external port characteristics, as shown in fig. 2.

In the actual conventional dc engineering, two sets of converter transformers are respectively composed of three single-phase double-winding transformers, and if fig. 2 is developed into a transformer winding connection form, as shown in fig. 3, the valve-side bushing connection of the converter transformer is as shown in fig. 4.

For a high-capacity flexible direct-current transmission converter station, a valve set of the high-capacity flexible direct-current transmission converter station is mostly an MMC (modular multilevel converter), a true bipolar connection is adopted, and a converter transformer generally only needs a single-group YnD connection form. In order to ensure that the ac side and the dc side access the same voltage class, this embodiment provides a general converter transformer suitable for a ± 500KV converter station, which can be implemented by the following scheme:

(1) as shown in fig. 5, three Y-type single-phase double-winding converter transformers and three D-type single-phase double-winding converter transformers are uniformly connected, and the ac power grid side is maintained unchanged, and still each winding is respectively incorporated into the ac power grid; on the converter valve side, a1-X1 winding of a Y-type single-phase double-winding converter transformer and a2-X2 winding of a D-type single-phase double-winding converter transformer are connected in series to form a new winding a1-X1-a2-X2, and the other two phases are similar to each other, so that the insulation level of the two windings does not need to be changed, and the newly formed three windings are connected into a star shape (namely Y-type);

(2) the 6 single-phase double-winding converter transformers are reordered in the sequence of A1-A2-B1-B2-C1-C2, and the sequence of the valve sides of the converter transformers correspondingly comprises the following steps: a1-a2-b1-b2-c1-c2, after the converter transformer is modified in the mode, the converter transformer is convenient to wire without increasing the insulation distance, and the valve side bushing wire of the converter transformer is shown in fig. 6. This embodiment is directed against 500kV level and every utmost point only the converter station of single converter, reforms converter transformer into YnY wiring, has solved the problem of high pressure overline, has reduced valve hall load to reduce and the degree of difficulty of construction and maintenance.

The foregoing is illustrative of the preferred embodiments of the present invention, and it is to be understood that the invention is not limited to the precise forms disclosed herein, and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the invention as defined by the appended claims. But that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention, which is to be limited only by the claims appended hereto.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "inner", "outer", and the like indicate the position or positional relationship based on the position or positional relationship shown in the drawings, or the position or positional relationship which is usually placed when the present invention is used, and are only for convenience of description and simplification of the description, but do not indicate or imply that the device or element to which the present invention is directed must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," and "connected" are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; either a wired or wireless connection.

Claims

1. A general converter transformer suitable for a +/-500 kV converter station comprises three Y-shaped single-phase double-winding converter transformers and three D-shaped single-phase double-winding converter transformers, and is characterized in that a converter valve side winding of a first Y-shaped single-phase double-winding converter transformer and a converter valve side winding of the first D-shaped single-phase double-winding converter transformer are connected in series to form a first winding, a converter valve side winding of a second Y-shaped single-phase double-winding converter transformer and a converter valve side winding of a second D-shaped single-phase double-winding converter transformer are connected in series to form a second winding, a converter valve side winding of a third Y-shaped single-phase double-winding converter transformer and a converter valve side winding of a third D-shaped single-phase double-winding converter transformer are connected in series to form a third winding, and the first winding, the second winding and the third winding are connected to form a Y-shaped topological structure.

2. A universal converter transformer suitable for a ± 500KV converter station according to claim 1, wherein the converter valve side windings of the D-type single-phase double-winding converter transformer in the first winding, the second winding and the third winding are connected to form a Y-type topology.

3. The universal converter transformer applicable to +/-500 KV converter stations as claimed in claim 1, wherein the AC power grid side windings of the three Y-type single-phase double-winding converter transformers and the three D-type single-phase double-winding converter transformers are respectively incorporated into an AC power grid.