WO2018046208A1 - Transformer for high-voltage direct-current transmission - Google Patents

Abstract

The aim of the invention is to provide a compact and cost-effective arrangement (1) for connecting a converter (15) to a high-voltage network carrying an alternating current, said arrangement comprising a number of single-phase transformers (2, 3, 4) that each comprise a valve winding (7) for connecting the converter (15) and a network winding (8) for connecting to the high-voltage network, where a valve end (10) of the valve winding (7) is connected to an outside connection (12) of a valve passage (11) and an interconnection end (20) of the valve winding (7) is connected to the interconnection end (20) or the valve end (10) of the valve winding (7) of another single-phase transformer (2, 3, 4) of the arrangement (1). To this end, each interconnection end (20) is connected to the interconnection end (20) or the valve end (10) of a single-phase transformer by means of a connection unit (21), and each connection unit (21) comprises a connection housing (22) filled with an insulating fluid, in which an electroconductive jumper (23) extends.

Description

description

The invention relates to an arrangement for connecting a Um ^¬ judge to an AC leading high-voltage network with a number of single-phase transformers, each having at least one valve winding for connecting the inverter and ei ^¬ ne network winding for connection to the high-voltage network, wherein a valve end of each valve winding is connected to an open air connection of a valve feedthrough and a interconnection end is connected to the valve winding of another single-phase transformer of the arrangement. Such an arrangement is already known to the person skilled in the art. Thus, for example looking inverter and in particular Umrichterventile a Hochspannungsgleichstromübertra- confining (HVDC) system comparable alternating voltage side through a transfor ^¬ mator with an alternating current leading power grid connected. The said high-voltage network is, for example, a supply network with connected consumers or via an infeed network which is connected to a generator. In the latter case, the electrical power provided flows through the assembly and the inverter, which converts the AC voltage to DC voltage to reduce transmission losses. Said inverter is on the DC side connected to a further ent ^¬ speaking constructed inverter, said second inverter is also the alternating voltage side connected to a genus tung proper arrangement. For outputs above 300 MVA per 6-pulse valve group, the

Inverter transformers no longer three-phase built. Rather, a number of single-phase transformers is used, wherein the number of transformers, the number of phases of the respective alternating-voltage network angschlossenen speaks ^¬ ent. A single-phase transformer can be designed as a two or three winders, the former in YY or YD circuit feeds a six-pulse inverter and the latter with a YY / YD circuit, a 12-pulse inverter.

In general, a generic arrangement thus has three single-phase transformers, the valve side have a star or delta connection. Each of these single-phase transformers is equipped with at least one valve winding and a network winding. Each valve winding is connected at least at one end to the inverter and the mains winding to the high-voltage network. For this purpose, usually high voltage feedthroughs are used. According to the prior art, two or more passages are provided on the converter side or in other words on the valve side, one for each end of each valve winding. Since these valve ^{¬ passes} a mixed voltage load from AC voltage and DC voltage are exposed, special measure ^¬ measures are required for Feldabsteuerung, making the valve ports are very large, very heavy and very expensive. Furthermore, in the transformer for connecting the valve feedthrough a complex barrier system for

Feldabsteuerung at the transition insulating body implementation - valve diversion required, which is time-consuming to manufacture and thus also expensive.

The object of the invention is therefore to provide an arrangement of the type mentioned, which is compact and inexpensive, with the number of required valve bushings is reduced.

The invention solves this problem in that at least one connection end is connected via a connection unit with the Ven ^¬ tilwicklung another single-phase transformer of the inventive arrangement, each connection unit has a filled with an insulating fluid connec ^¬ tion housing in which extends an electrically conductive connection conductor , According to the invention, the single-phase transformers of the arrangement according to the invention are no longer equipped per valve winding, each with two valve bushings. Rather, the single-phase transformers according to the invention for at least one valve winding only have only one valve feedthrough for the phase connection to the converter. The other end of the valve coil, which is not connected to the inverter and which is called herein Verschaltungsende, in the invention a with isolator insulated electric connection with the respective Verschal ^¬ line end or the valve end of another valve winding of another single-phase transformer connected the inventive ^¬ Shen arrangement. In the context of the invention, each connection unit has a connection conductor extending through a connection housing, the connection housing being filled with insulating fluid. According to the invention there ^¬ forth costly valve passage for the external connection of said valve coil to dispense with the drive at least. For this reason, the arrangement according to the invention is less expensive than previously known arrangements.

According to a variant, each single-phase transformer has two or more valve windings. In the context of the invention, it is sufficient that only one of the two valve windings is connected via a connecting unit with a valve winding of another single-phase transformer. In a preferred embodiment of the invention, however, each valve end of a single-phase transformer is connected via a connection unit with a valve winding of another einphasi ^¬ gen transformer.

According to an expedient further development of the invention, each single-phase transformer has a transformer tank filled with the insulating fluid, which has at least one connection connection for connecting a connection unit. According to this variant of the invention, the single-phase transformers have the same insulating fluid as the connection unit. In this way, the assembly of the arrangement is simplified. The connecting unit may not have as ^¬ ago but, over the oil space or better the interior of the transformer tank the single-phase transformers fluid-tightly be sealed off. In addition, the Verbin ^¬-making unit must be not filled with insulating liquid before installation, but can be circuit connection slowly filled with insulating fluid after installation of the encryption. It is therefore by no means necessary for the connection unit and the boiler to be designed separately from one another.

According to a further variant of the invention, each single-phase transformer has two or three connection connections. According to this variant, it is possible, too

Triangle circuits or the like according to the present invention to realize. Three wiring connections are preferably established in the case of two valve windings per single-phase transformer. A Verschaltungsanschluss may be arbitrarily ^¬ equipped as part of the invention. He is, for example in a Be ^¬ tenwand of the boiler as a flange connection. Before Trains t ^¬ however Verschaltungsanschluss is arranged in the lid of Kes ^¬ sels.

In a preferred variant, each connection connection is equipped with a closing valve. According to this Va ^¬ riante the closing valve, the isolator of the single phase transformers can after assembly of the connection unit to the Verschaltungsanschlüssen between which the connection unit extends, are open so that then flows into the inner housing of the connecting unit.

The connection housing is configured, for example, in the shape of a pipe or box.

Notwithstanding this, the connection unit is fluid-tight from ^¬ formed and already before assembly with the single-phase Transformers filled with an insulating fluid. Here, the Verschaltungsanschluss the boiler the single-phase transformers transfor ^¬ is designed as a socket so that, by simple and fast insertion of the free ends of a respective connection unit in a connector of the single-phase transformers Verschaltungs- the Verschaltungsenden the terminal are connectable. Thus, for example, a fluid-tight seal of the boiler to the connection connection could be formed as a fluid-tight membrane.

Advantageously, each connection unit to a hard ^¬ isolation material for isolating the connection conductor. As was further already explained, the head of the valve ^¬ development both an AC voltage and a DC voltage are exposed. Therefore, special measures for

Field control necessary. The Feldabsteuerung is usually done with the help of a solid insulation for isolating the connection conductor. The same applies to a arranged within the boiler of the respective single-phase transformer winding ^¬ connection line, which extends between the Verschaltungsende each valve winding of the respective single-phase transformer and its Verschaltungsanschluss. This winding connection line is also equipped with a solid insulation, in order to meet the respective requirements due to the said double loads.

The solid insulation includes, for example, an insulation of the winding made of paper or other known winding insulation. In addition, however, the solid insulation may also comprise a barrier system of an insulating material known as such. The barrier system is made, for example, from a suitable cellulosic material. The barrier system may for example be embodied as Laby ^¬ rinth structure with curved and interlaced portions, a controlled

Absteuerung allow high electrical field strengths. Conveniently, each connection unit has an outer connection housing which is equipped with a fluid discharge opening and / or a vent opening. According DIE ser advantageous development, the connection unit may be fixedly mounted on the respective vessel, for example on the De ^¬ ckel of the respective single-phase transformer, for example, the boiler side wall. In this variant, the connection unit is not yet filled with insulating fluid during assembly on site. To fill the connection unit with insulating fluid, a closing valve of the connection connection is opened after installation, whereby a sufficiently high vacuum has previously been applied in the connection ^housing via the ventilation opening, in order to keep the insulating fluid from moistening by still existing in the connection housing

Avoid residual air as much as possible.

For disassembly, the connecting housing is equipped with a fluid outlet opening, which is expediently arranged in a lower collecting area of the insulating fluid.

Further expedient refinements and advantages of the inven ^¬ tion are the subject of the following description of embodiments of the invention with reference to the figures of the drawing, wherein like reference numerals refer to like-acting components and wherein

1 shows an embodiment of the arrangement according to the invention in a schematic representation,

FIG. 2 shows the arrangement according to FIG. 1 in a perspective view,

FIG. 3 shows a single-phase transformer of the arrangement according to FIG

 FIG. 2 in a sectioned side view,

Figure 4 shows another embodiment of the erfindungsge ^¬ MAESSEN arrangement in a schematic view and Figure 5 shows the arrangement of Figure 4 in a perspective view. Figure 1 shows an embodiment of the inventive arrangement 1 in a schematic representation.

The arrangement 1 has three single-phase transformers 2, 3 and 4, each having a filled with an insulating fluid and here with a mineral oil boiler 5. At

However, in the context of the invention, other insulating fluids, for example natural or synthetic ester oils, can be used instead of a mineral oil. In the Trans ^¬ formatorkessel 5 are each an active part 6 is arranged in WO each active part 6, a valve 7 and a winding network ^¬ winding 8 has. The network winding 8 and the valve winding 7 are inductively coupled together via a magnetizable core 9, so that an input voltage can be converted into a ge ^¬ desired output voltage. The ratio to the output voltage depends on the ratio of the number of turns of mains and valve winding 7 and 8.

Each valve winding 7 is connected with its valve end 10 to the high-voltage conductor of a valve bushing 11, which is attached to the transformer tank 5 and extends in a longitudinal direction to a free end and there forms an open air connection 12. The open air connection 12 is connected via air-insulated connection conductor 13 with an AC voltage terminal 14 of an inverter 15, which corresponds to the three phases of the arrangement 1 corresponding to three

Inverter valves 16, 17 and 18 has. The topology of the converter and the structure of the valves 16, 17 and 18 are known in principle, so that a more precise embodiment can be dispensed with here. It should be noted at this point, however, that each valve 16, 17 and 18 next to the said AC voltage connection 14 has two DC voltage connections not shown in the figures. The Umrich ^¬ ter 15 is used to convert a direct current into an alternating selstrom or vice versa. In the exemplary embodiment shown in FIG. 1, power is to be transferred to an alternating current-carrying high-voltage network. The inverter is therefore operated as an inverter. The alternating voltage network is figuratively not shown. To connect the Transformato ^¬ Ren 2, 3, 4 to the alternating voltage network are each two power terminals 19, which are each connected to one end of the Netzwick ^¬ development. The structure and the design of the AC power supply terminals 19 is basically arbitrary within the scope of the invention. It is, for example, suitable imple ^¬ conclusions which have a free air connection as the valve passage 11 and extending to the latter in a longitudinal direction from the boiler 5 away, so the necessary voltage ^¬ strength between the outdoor connection and lying on Erdpo ^¬ tential Boiler 5 provide.

In contrast to previously known arrangements, the arrangement according to the invention shown in Figure 1 1 single-phase transformers transfor ^¬ 2, 3 and 4, the valve 7 comprises a winding Verschaltungsende 20, which via a connection unit 21 with the Verschaltungsende 20 of a further single-phase

Transformers 2, 3 and 4 is connected. Thus, for example, the interconnection end 20 of the single-phase transformer 2 is connected to the interconnection end 20 of the single-phase transformer 3 and simultaneously to the interconnection end 20 of the single-phase transformer 4. In other words, the interconnection ends 20 of the respective valve windings 7 form a neutral point. To connect the interconnection ends 20 to a star point in the context of the invention, the Verbindungsseiheit 21, which has a äuße ^¬ res also lying on a ground connection housing 22 in which a connecting conductor 23 extends. The connector housing 22 is filled with a minerali ^¬'s oil as insulating fluid. At this point, it should be pointed ^¬ times out that belie- in the invention Bige insulating fluids, for example, ester oils can be used.

FIG. 2 shows the arrangement according to FIG. 1 in a perspective view, in which the network-side connections 19 are not shown for reasons of clarity. In particular, it can be seen that the valve bushings 11 extend in a longitudinal direction from the transformer tank 5 of the respective single-phase transformers 2, 3, 4 and form an open air connection 12 at their end remote from the transformer tank 5. In particular, however, the location of the connection unit 21 is shown in more detail. It is recognizable ^¬ bar, that the connection units 21 each comprise a tubular shaped connecting Here housing 22, for example of the single phase of a Verschaltungsanschluss 24,

Transformer 2, to the interconnection terminal 24 of the ^¬ phasigen transformer 3 and from there to the interconnection ^¬ connection 24 of the transformer 4 extends. In the embodiment shown in Figure 2, the arrangement 1 has three valve bushings 11. Each valve bushing 11 is mechanically held on the boiler 5 one of the three single-phase transformers 2, 3, 4, which forms a flange connection not shown figuratively.

FIG. 3 shows in a sectional side view the single-phase transformer 2 of the arrangement 1 according to FIG. 1 or 2, wherein the other single-phase transformers 3 and 4 are designed almost identically to the shown single-phase transformer 2. The single-phase transformer 2 has, as already stated, the transformer tank 5, which is filled with insulating fluid. It can be seen that the valve ^¬ end 10 of the valve coil 7 is connected via a connecting line 26 with a high voltage conductor 31st The connection line 26 extends to a connection electrode

27, which is arranged in a dome-like extension 29 of the transformer tank 5 and surrounded by a barrier system 34. The valve bushing 11 is designed like a column and extends in a longitudinal direction from a contact end 30 which contacts the connection electrode 27, to the non figuratively shown in Fi ^¬ gur 3 free air connection 12. In the interior of the valve passage 11, a high voltage conductor 31 is provided, the electrical connection between the

Electrode 27 and the outdoor terminal 12 provides. Here, the high voltage conductor 31 extends within an insulator 32, which is equipped for example with a resin or flüssi ^¬ gen insulating oil. To increase the creepage distance, the insulator of the valve bushing 11 is externally provided with screen profiles 33.

In the dome-like extension 29 comes at the transition from the conical insulator to the solid-insulated connection line 26 is a figuratively not shown in detail barrier system 34 is used, which serves to control the high field strengths occurring there.

The connecting line 26 is surrounded by a solid insulation 37, for example umgautscht. The material of the solid insulation ^¬ material is dependent on the prevailing maximum operating temperature in the transformer tank. 5 For smaller DC voltages, paper insulation may be sufficient. The connection end 20 is connected via a likewise umgautschte connection line 35 to the connection unit 21. It can also be seen that the connecting conductor 23 are also equipped with a solid insulation 34 in order to withstand the DC and AC stresses. The connecting conductor 23 may be equipped with deviating embodiments of the invention with a barrier system. In the embodiment shown, the transformer 2 is arranged outside a valve hall, wherein the Ven ^¬ tilddurchführung 11 extends through an outer wall 36 of the valve hall.

FIG. 4 shows a schematic view corresponding to FIG. 1 of a further embodiment of the invention. Order 1, which differs from the embodiment shown in Figure 1 in that the single-phase trans ^¬ formators 2, 3 and 4 are no longer mitei ^¬ nander connected to a star point, but form a so-called triangular circuit. Therefore, the connection end 20 of the transformer 2 is connected to the valve end 10 of the valve winding 7 of the single-phase transformer 4. The Verschal ^¬ line end 20 of the valve 7 of the single-phase transformer winding 4 is, however, in turn connected to the valve end 10 of the single-phase transformer 3 and their Verschaltungsende 20 with the valve end 10 of the single-phase transformer. 2

Figure 5 shows the embodiment of Figure 4 in a perspective view. It can be seen that, in the selected triangular circuit, a connecting line 21 is provided between the single-phase transformer 2 and 3 and a further connecting line 21 between the single-phase transformer 3 and 4. In addition, a longer Ver ^¬ connecting line 21 between the transformers 2 and 4 is seen upstream. Each single-phase transformer 2, 3 or 4 thus has a plurality of interconnection terminals 24, that is to say two interconnection outputs 24 each. Incidentally, the construction corresponds to ^¬ inside the single-phase transformers, the construction according to FIG. 3

Claims

claims An arrangement (1) for connecting an inverter (15) to an AC high-voltage power grid with a number of single-phase transformers (2,3,4), each  - At least one valve winding (7) for connecting the inverter (15) and  - Have a network winding (8) for connection to the high-voltage network, wherein  - One valve end (10) of each valve winding (7) with a Outdoor connection (12) of a valve bushing (11) and  a connection end (20) is connected to the valve winding (7) of another single-phase transformer of the arrangement (1), d a d u r c h e c e n c i n e s that at least one interconnection end (20) is connected via a connection ^¬ unit (21) with the valve winding (7) of another single-phase transformer (2,3,4) of the assembly (1), wherein each connection unit (21) filled with an insulating fluid Connection housing (22), in which an electrically conductive connection conductor (23) extends. 2. Arrangement (1) according to claim 1, d a d u r c h e c e n c i n e s that each single-phase transformer (2,3,4) having a transformer tank filled with the insulating fluid (5), the Wenig ^¬ least a Verschaltungsanschuss (24) for connecting a connection unit (21). 3. Arrangement (1) according to claim 2, d a d u r c h e c e n c i n e s that each single-phase transformer (2, 3, 4) has two or three connection terminals (24). 4. Arrangement (1) according to claim 2 or 3, characterized in that each connection port (24) is provided with a closing valve. 5. Arrangement (1) according to one of claims 2 to 4, d a d u r c h e c e n c i n e s that each connection unit (21) has a solid insulation for insulating the connection conductor (23). 6. Arrangement (1) according to one of claims 2 to 5, d a d u r c h e c e n c i n e s that within the transformer tank (5) a ^{Anschlußlei ¬} ter (35) between each Verschaltungsende (20) and the Ver ^¬ circuit connection (24) extends, which is equipped with a solid ^¬ insulation. 7. Arrangement (1) according to claim 5 or 6, d a d u r c h e c e n c i n e s that the solid insulation comprises a barrier system (34). 8. Arrangement (1) according to one of the preceding claims, characterized in that a each connection unit (21) is designed as a pluggable connection unit. 9. Arrangement (1) according to claim 8, d a d u r c h e c e n c i n e s that each connection housing (22) is equipped with a fluid discharge opening and / or a vent opening. 10. Arrangement according to one of the preceding claims, characterized in that a each interconnection end (20) is connected via a connection unit (21) to a valve winding (7) of another single-phase transformer (2, 3, 4).