EP1973126A1 - Adjustable primary voltage coil for a dry-type transformer and HV/LV transformer comprising same - Google Patents

Abstract

The wafer (10-1-10-4) has outlets of 6 to 7 kilovolts spaced at 120 degrees with an inlet at 0 Volts of a rolling bearing. The inlets and outlets are accessible from exterior of a resin ring. One of the outlets corresponding to different voltage of the other outlet is accessible from exterior of the ring. The ring has lateral protrusions (12-0-12-2), where each inlet and outlet are connected to different protrusions and opens on both sides of the protrusion.

Description

TECHNICAL AREA

The invention generally relates to the realization of power transformers for the distribution of electrical energy, single phase or multiphase, of the coated or immersed type, in which the primary or secondary voltage can be modulated.

In particular, the invention relates to a high-voltage coil, often external, for an active part of a transformer, made in the form of stacked wafers whose relative orientation makes it possible to modify the input voltage, as well as pancakes adapted for this purpose.

The invention also relates to transformer modules and the unit cells of these modules, formed with a variable number of wafers.

STATE OF THE ART

For power distribution, the grid voltage is usually lowered from the "high voltage" level (between 5 and 52 kV) to a "low voltage" level (less than 1000 V); high voltage / low voltage transformers (HV / LV) allow this modification, at the cost of significant heat exchange. Traditionally, these transformers use mineral oils as insulating and heat transfer fluid.

In particular in order to preserve the environment and to avoid the risk of fire, so-called coated or solid-insulated transformers have been developed in which the concentric primary and secondary windings are each embedded in dielectric molding resin. In addition to electrical insulation, the resin also exchanges heat with the air to cool the transformer. The coated power transformers can also be shielded, in particular at the external HV coil, to increase their isolation from the environment. An exemplary embodiment is given in the document WO 98/10446 .

The process of producing the coils is however heavy, and this type of coated transformer remains expensive. In particular, the windings are usually manufactured to order from a specification of the customer, particularly depending on the voltages he wishes to treat and the power envisaged.

SUMMARY OF THE INVENTION

Among other advantages, the invention aims to overcome the disadvantages of existing transformers by rationalizing the range of windings, in particular by producing coils that can be adapted to different power transformers and / or primary voltage.

The invention relates in particular to a coil, preferably the high-voltage coil, made by superposition of power wafers comprising a plurality of outputs. Depending on the connection on a wafer and / or between two consecutive power wafers, it is possible to adjust the input voltage by increasing the input power input; Depending on the number of slabs, it is possible to adjust the power.

In one of its aspects, the invention relates to a power wafer embedded in an insulating resin and having an input and a plurality of accessible outputs, preferably two, of the winding of turns. Advantageously, the angular distribution of the terminals relating to the inputs / outputs is regular. Preferably, the inlets / outlets are accessible from each face of the wafer thanks to the presence of resin side overmoldings in which a connection device allows the insertion of a connector cooperating with another wafer. A preferred example concerns two outputs, for example at 6 and 7 kV, and an equidistant 120 ° input opening into three protuberances.

In another aspect, the invention relates to a coil composed of a plurality of superimposed power wafers connected together in series and / or in parallel, one of at least one, preferably all, of the power wafers comprising a plurality of different voltage outputs. Advantageously, all the power wafers are identical, and in particular comprise a protrusion for each input and output terminal in which a connector can be inserted to directly connect them; plugs may be placed in the non-electrically connected protuberances. The adjustment of the primary voltage is then achieved by the choice of the connection (series or parallel) and the relative orientation of the power wafers.

According to a preferred embodiment, an HV / LV transformer coil according to the invention comprises a plurality of superimposed superimposed power wafers, associated with two end wafers, each end wafer comprising an outward connection terminal. . The power wafers are thus simplified and standardized as much as possible, and it is possible, by the end wafers, to adapt to the external connections of the customer and / or to the desired modularity of the transformers.

The end wafers may be identical in design, or one of them may be provided with means for connection with the terminal of the other end wafer. At least one of the end slabs is adapted to be connected with another slab (for example the end slab of another spool according to the invention), and / or for the customer connection.

A HV coil according to the invention may be associated with a LV coil in order to produce an active transformer part. Three active parts can be associated with a magnetic circuit so as to produce a three-phase transformation module.

BRIEF DESCRIPTION OF THE FIGURES

Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention, given by way of illustration and in no way limiting, represented in the appended figures.

The figure 1 schematically illustrates the realization of a three-phase transformation module which can be manufactured with wafers according to the invention.

The figure 2 represents a power wafer according to a preferred embodiment of the invention as well as the associated connectivity.

The Figures 3A and 3B show obtaining coils of two different primary voltages with the same wafers according to the invention.

The Figures 4A and 4B represent preferred embodiments of end wafers that can be associated with a coil according to the invention.

DETAILED DESCRIPTION

The invention will be described in relation to a stack of four identical power wafers comprising outputs, in particular at 6 and 7 kV, spaced by 120 ° with a 0 V input of the winding. This embodiment is particularly advantageous because, while not excessively complicating the manufacture and maintenance, it makes it possible to cover the majority of the desired applications (in particular the transformers of 6, 7, 12, 14, 18, 21, 24.28 kV). However, it will be clear to those skilled in the art that this illustrative example can be adapted to the application and that, in particular, other choices of output voltages are possible, that a different number of wafers can be stacked, each of which can include more outputs if desired, such as three outputs spaced 90 °, ...

The power wafers according to the invention are used for the manufacture of HV transformer coils which are used in the composition of three-phase transformers. As illustrated in figure 1 a transformer 1 comprises three cells 2 of identical characteristics which are secured by yokes. Each cell 2 comprises, concentrically, a core 4 of magnetic circuit, which is preferably made from several sheets of magnetic sheet and an active part; each active part is composed of a coil BT 6, coated or impregnated with insulating resin, around which is placed a coil HT 8, also coated According to the invention, the HT coil 8 is composed of several superimposed power wafers 10; in particular, the power wafers 10 are preferably identical to reduce the number of industrial references. As usual, a wafer HT 10 consists of a winding of several conductive turns and an insulation system, for example a coating resin and / or impregnation; shielding can also be provided.

According to the invention, it is possible to increase the power by the number of wafers 10 but also to multiply the values of the primary tolerated voltages: at least one wafer 10, illustrated in FIG. figure 2 , has an input and several outputs corresponding to a different number of turns, and therefore to different voltage steps, that is to say that the set of turns extends between a first conductor end corresponding to an input and a second conductor end corresponding to an output, and further comprising at least one conductive port between the ends corresponding to an additional output. A connector system makes it possible to connect the inputs and the outputs of the power wafers 10 in series or in parallel so that the resulting coil 8 responds to several primary voltages.

In order to facilitate the connections, it is advantageous for the inputs and outputs, which may also be described as terminals, to be accessible at reproducible lateral locations of the power wafer 10, for example a connection cable may connect output similar to those present in the winding described in WO 98/10446 . However, according to a preferred embodiment, protuberances 12 are made, for example by overmolding the insulation resin 14, to open the inlet and outlet conductors of the wafers 10. In particular, the protuberances 12 comprise, at each end, an orifice 16, provided for example with a ring 18 which is connected to the input and output conductive ports of the coil winding; each orifice 16 can receive a connection element 20 in order to make the electrical connection with an adjacent coil 10: thanks to this geometry, a connection of the coils is also ensured.

In particular, for the embodiment presented above, each power wafer 10 is in the form of a resin ring 14 in which is embedded the winding of turns, provided with three protuberances 12 ₀ , 12 ₁ , 12 ₂ to 120 ° respectively corresponding to the input (0 V) of the coil winding and two outputs of different voltage steps, in particular 6 and 7 kV. The three protuberances 12 comprise an orifice 16 at each end in which can be inserted a connecting device 20 which can be conductive, such as a bicon 22, or insulating as a plug 24.

To make a transformer coil 8, the power wafers 10 are stacked: according to the scheduling of the conductive connection devices 22 in the protuberances 12 _i , different primary voltages are covered. Thus, as illustrated in figure 3A in order to obtain a primary voltage coil 24 kV, it is possible to use four power wafers 10 ₁ , 10 ₂ , 10 ₃ , 10 ₄ connected in series: bicones 22 are inserted between the input 12 ₀ and the output 12 ₁ at 6 kV of two adjacent pancakes. Advantageously, a device 24 of the insulating plug type is placed between the protuberances 12 ₂ not used, in order to stabilize the assembly and to provide insulation.

As illustrated in figure 3B , the same four power wafers 10, with a different relative orientation and another implementation of the conductive connectors 22 (and any insulating plugs 24), also provide a primary voltage coil 14 kV, the output is making on the second protrusion 12 ₂ of the fourth coil 10 ₁ (two sets of two wafers connected in parallel to 7 kV are put in series).

Although not shown, those skilled in the art will make changes in the location of the connectors of these four power wafers, and the resulting orientation of the wafers, for other possible voltages. Likewise, according to his need, he will adapt the number of pancakes. Furthermore, depending on the number of voltage steps of each power wafer, that is to say their number of outputs, and to cover all the combinations of connections between outputs, it is possible for example to set up a number higher inputs, or use more complex systems of connection, or to position the pancakes indifferently in both directions stack and face.

In order to facilitate the setting up of the active part of the transformer and in particular to standardize and stabilize the input and output connections of the HV coil 8, it is desirable to also make isolated end wafers 50 placed on the end faces of the coil 30, 40. In particular, each end plate 50 comprises protuberances 52 similar to those of the power wafers 10, provided with orifices, which advantageously only open on one side, in which connecting means such as the bicones 22 and the plugs 24 can be inserted; the orifices are also provided with a system for electrical conduction, for example of a similar nature to that of the power wafers 10 (rings 18, ...). The end wafers further comprise one or more input and / or output terminals 54 allowing the more "conventional" connection to external systems (connection cables, other wafer, etc.); the current supply terminals 54 may be lateral or localized on one face of the wafer 50. It is possible, according to the scheduling of the transformer modules, that the end wafers are then fixed orientation.

According to a first preferred embodiment illustrated in Figure 4A the two end wafers 50 are identical, simply turned over with respect to each other in order to position the orifice of the protuberances appropriately; each protuberance 52 is electrically connected to a terminal 54, which serves as a feed into the top and outlet slab into the bottom slab. This system minimizes the number of parts and also allows to position the input and output terminals in any relative orientation. The terminal can be doubled, preferably with two diametrically opposite input and output terminals, respectively.

It may be advantageous, according to another preferred embodiment illustrated in Figure 4B , to use an end wafer 50 ', preferably the wafer 50' upper, comprising both input terminals 54 'and 56' output, for example on its outer face, as described in the application patent FR 07 02011 entitled "Active part of a coated transformer with a connection system at one end and a modular HV / LV transformer including it ". The two output terminals 56 'are electrically connected to an access 58', for example lateral, which will be connected to the output terminal 54 of the lower wafer Previous 50; for example the access 58 'is positioned above the terminal 54 so as to use a connecting bar. This option makes the connection area more accessible, which can be particularly advantageous if transformer modules are connected in parallel in order to realize a modular transformation bench.

It is understood that the different embodiments, for connections and terminals in particular, can be combined according to the specifications and the size. Similarly, alternatives are possible.

• réaliser plusieurs modèles de transformateurs (puissance, tension primaire, système de connexion,...) avec peu de références industrielles ;
• réduire les délais et les coûts de fabrication par l'optimisation de l'outil industriel ;
• réduire les délais de livraison grâce à un assemblage sur des stocks que l'on peut optimiser ;
• réaliser un système permettant d'augmenter la VA locale, notamment en distribuant les pièces composant le transformateur individuellement et en les assemblant sur place ;
• réduire les coûts de maintenance, les bobines étant interchangeables.

The invention makes it possible, among other advantages, to:

• realize several models of transformers (power, primary voltage, connection system, ...) with few industrial references;
• reduce manufacturing time and costs by optimizing the industrial tool;
• reduce delivery times by assembling inventory that can be optimized;
• implement a system to increase the local VA, including distributing transformer component parts individually and assembling them locally;
• reduce maintenance costs, the coils being interchangeable.

Claims (11)

Power wafer (10) for a high voltage / low voltage transformer comprising an annular winding of turns between an input and a first output, and a coating (14) of insulating resin, the input and the first output being accessible from the outside the coating (14), characterized by the presence of at least a second output of the winding, corresponding to a voltage different from the first output, accessible from outside the coating (14). Power wafer according to claim 1 comprising two outputs and an inlet each separated by 120 °. Power wafer according to one of claims 1 or 2 wherein the coating (14) comprises lateral protuberances (12), each inlet and each outlet being connected to a different protuberance and opening on either side of the protuberance (12). A power wafer according to claim 3 wherein each protuberance (12) comprising an inlet or an outlet comprises a conductive system (18) from the winding of turns to an orifice (16) in which an electrical connector (22) can to be inserted. High voltage (30, 40) high voltage / low voltage transformer coil comprising a superposition of a plurality of power wafers (10) having an input and an output, at least one power wafers being defined according to one of claims 1 to 4, and each power wafer (10 ₁ ) being connected to at least one other power wafer (10 ₂ ) by at least one conductive connection device (22). A high voltage (30, 40) high voltage / low voltage transformer coil comprising a superposition of a plurality of power wafers (10) according to claim 4, each power wafer (10) being connected to at least one another power wafer by at least one conductive connection device (22) in the orifice (16) of a protuberance (12). Coil according to claim 6 comprising insulating plugs (24) in the orifices (16) not connected by conductive connection devices (22). The coil (30, 40) according to one of claims 5 to 7 further comprising at least a first end wafer (50) which comprises at least a first input / output terminal (54) of the current electrically connected to the at least one connection system (52) which can be associated with a power wafer (10) by a conductive connection device (22). The coil of claim 8 further comprising a second end wafer (50 ') which comprises two current input terminals (54') electrically connected to at least one connection system (52 ') which may be associated with a a power wafer (10) by a conductive connecting device (22) and two output terminals (56 ') associated with an access (58') connectable to the first terminal (54) of the first end wafer ( 50). Transformer active part concentrically comprising a low voltage coil (6) and a high voltage coil according to one of claims 5 to 9. Three-phase transformer module comprising three active parts according to claim 10 and a magnetic circuit.

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