EP2567388B1 - High- or medium-voltage electrical device including a submerged active induction portion having reduced noise - Google Patents

Description

TECHNICAL AREA

The invention relates to a high or medium voltage electrical switchgear, such as a transformer or an inductance coil, comprising an active part by induction immersed in a dielectric fluid.

The invention relates to the reduction of the emission noise of such electrical equipment.

More particularly, it relates to the reduction of the part of the noise due to the acoustic waves emitted by the active part by induction of the electrical equipment and propagated in the dielectric fluid medium to the walls of the immersion tank filled with the fluid dielectric, such as oil.

The apparatus particularly targeted by the invention are transformers, particularly those of power and distribution in an electrical distribution network, and the inductance coils.

PRIOR ART

In electrical equipment, such as transformers or inductance coils, with an active part by induction immersed in a fluid dielectric, it is known that a significant part of the radiated noise is due to the propagation of acoustic waves emitted by the induction part in operation in the dielectric fluid medium and propagating to the walls of the tank which thus constitute somehow dominant acoustic radiation surfaces.

Many solutions have already been proposed in the prior art to reduce this part of the noise.

We can mention here the solutions described in the very old patents GB 925522 , US 3102246 and US 3305813 , which consist in significantly increasing the compressibility of the fluid by the use of a set of several flexible hollow tubes whose breathing resonance in the dielectric fluid medium is tuned to the frequency of acoustic phenomena to be attenuated. The local increase in frequency of the compressibility of the dielectric fluid medium modifies the apparent compressibility modulus of the latter, but does not concretely prevent the acoustic waves emitted by the active part by induction from reaching and thus exciting the walls of the tank. In other words, the solutions according to these documents are not very effective because the walls of the tank remain significant acoustic radiation surfaces and therefore the noise of the transformers remains high.

More recently, a solution has been proposed in the patent US 6,661,322 : it consists of arranging structures in the form of cylindrical slabs arranged either against the tank walls or around the active part. These cylindrical pancakes also aim at a significant decrease in the apparent compressibility of the dielectric fluid medium (in this case oil) so as to absorb the waves propagating from the active part towards the cell walls. As for the solutions described in the previously mentioned patents, the increase in the apparent compressibility of the dielectric fluid medium in which the active part is immersed by induction does not guarantee the reduction of the excitation of the cell walls by the waves emitted by said active part. In other words, such a solution does not prevent the waves emitted by the active part by induction from reaching the cell walls, which therefore remain important acoustic radiation surfaces.

Improved noise reduction devices have already been proposed for restrictive applications in which they are immersed in a liquid and subjected to very substantial hydrostatic pressures. Thus, patents US 5138588 and FR 2730335 describe noise reduction devices used in underwater acoustics and which consist of tubular structures embedded in an elastomeric matrix to ensure their tightness to immersion at great depth. It is thus planned to rigidly fix these tubular structures to the hulls of ships. As such, they are unsuitable for a tank application of electrical equipment, such as a transformer, because their rigidity is too important.

The document US 1 846 887A relates to electrical equipment of the type having a tank surrounding an active part, the tank being filled with a dielectric fluid, the apparatus being provided with passive means for acoustic reduction of the waves originating from an active part and propagated in the fluid dielectric, the passive means of acoustic reduction being in the form of a hollow structural element.

Therefore, an object of the invention is to propose an effective reduction solution from the noise of a high or medium voltage electrical equipment due to the acoustic waves emitted by the active part by induction and propagated by the medium. dielectric fluid surrounding said active portion.

A particular object of the invention is to propose a solution compatible with the technological and economic requirements of the field of transmission and distribution of electricity at high or medium voltage.

STATEMENT OF THE INVENTION

To do this, the subject of the invention is a high or medium voltage electrical apparatus according to claim 1.

The passive acoustic reduction means are hollow structural members, impervious to the dielectric fluid, arranged at regular intervals and forming a barrier at a distance from the walls of the tank, the space between two adjacent structural elements being adapted to allow a portion of the structure to pass through. waves originating from the active part and propagated in the fluid without introducing a phase shift thereby constituting one of the two groups of waves, each structural element being adapted to be excited by one of its so-called internal faces by the other part of the waves coming from the active part and propagated in the fluid and reemitting the other group of waves in opposite phase to the first wave group and thus creating the interference between the two groups of waves , in an area remote from the walls of the tank so as to at least limit their amplitude before contact with the latter.

The term "active part by induction" means electromagnetic induction elements, such as an electromagnetic circuit and windings in HV or MV transformers or in inductance coils.

The passive acoustic reduction means according to the invention are advantageous because of their simplicity of implementation and a reduced cost of production.

Thus, thanks to the structural elements according to the invention, an acoustic barrier is formed and an interferential field is created behind it, that is to say in the zone situated between the acoustic barrier and the walls of the tank, limiting the acoustic effect resulting from the mechanical excitation of the walls of the tank containing the dielectric fluid by the acoustic waves.

• un traversant la barrière sans subir de déphasage,
• l'autre excitant la face interne de la barrière (faces internes de tous les éléments structurels) et réémis en opposition de phase par les faces externes des éléments structurels de la barrière.

In other words, the incident sound pressure waves generated by the components of the part active by induction and reaching the acoustic barrier formed by the structural elements according to the invention are divided into two groups of waves including:

• a crossing the barrier without undergoing phase shift,
• the other exciting the inner face of the barrier (internal faces of all the structural elements) and reemitted in phase opposition by the outer faces of the structural elements of the barrier.

The minimization of the resulting effect on the walls of the tank is then obtained by a compensation mechanism between two virtual sources, the first (Q +) linked to the incident wave and crossing the barrier, and the second (Q-) linked to the incident wave exciting the structural elements of the barrier and reemitted with an opposite phase by these structural elements. The compensation mechanism according to the invention obtained by the structural elements constituting the barrier is represented by figure 3 .

In other words, the invention essentially consists in producing, within an electrical equipment tank filled with dielectric fluid, a noise attenuator by incident wave division and phase opposition between these divided waves. The noise attenuator according to the invention is passive, that is to say that it does not require the use of any active electrical and / or mechanical means to achieve the interference field in phase opposition.

According to a variant, the structural elements comprise metal tubes with a constant inner section over their height, each tube being closed at each of its ends by a dielectric fluid-tight device.

The structural elements are preferably mounted in the vessel via vibratory decoupling means. This results in a significant reduction of low frequency noise, related to the transfer of acoustic energy by the dielectric fluid.

For the sake of simplicity of implementation and not having to change the design of the other elements of the electrical equipment, such as the tank, it is expected that the fixing through the vibrating decoupling means is made to a frame rigid arranged in the tank.

To ensure a sufficiently large interference field, the surface of the structural elements is at least equal to two thirds of the surface of the barrier.

The invention also relates to an electrical apparatus described above which constitutes a transformer or an inductance coil.

• la géométrie et le matériau utilisés pour les éléments structurels (métalliques ou non métalliques), ainsi que la nature de son contenu (gaz, mousse ou élastomère), qui va conditionner la conversion entre onde incidente et onde réémise en opposition de phase par ces structures. En particulier, on veille à définir une géométrie et un ou des matériaux pour mettre en oeuvre le mécanisme de compensation entre les ondes réémises par les éléments structurels adjacents et celles traversant leur espace de séparation sans opposition de phase,
• le pas de la barrière acoustique, c'est-à-dire la distance entre deux éléments structurels adjacents, qui fixe en quelque sorte la répartition entre les contributions respectives de l'onde incidente et de l'onde réémise derrière la barrière. Comme indiqué précédemment, le pas doit être tel qu'il permette aux éléments structurels de représenter une couverture d'au moins 2/3 de la surface totale de la barrière,
• la distance de la barrière vis-à-vis des parois de la cuve. Cette distance doit être suffisante pour permettre au champ interférentiel selon l'invention d'être mis en oeuvre entre la barrière et les parois de la cuve.
• les caractéristiques du fluide diélectrique (huile minérale ou autre).

Those skilled in the art will take care to aim for optimum efficiency at a given frequency in the design and implementation to adjust the following parameters:

• geometry and material used for structural elements (metallic or non-metallic), as well as the nature of its contents (gas, foam or elastomer), which will condition the conversion between incident wave and re-emitted wave in phase opposition by these structures. In particular, care is taken to define a geometry and one or more materials to implement the compensation mechanism between the waves re-emitted by the adjacent structural elements and those crossing their separation space without phase opposition,
• the pitch of the acoustic barrier, that is to say the distance between two adjacent structural elements, which fixes in a way the distribution between the respective contributions of the incident wave and the wave re-emitted behind the barrier. As indicated above, the pitch must be such that it allows the structural elements to represent a coverage of at least 2/3 of the total surface of the barrier,
• the distance of the barrier vis-à-vis the walls of the tank. This distance must be sufficient to allow the interference field according to the invention to be implemented between the barrier and the walls of the tank.
• the characteristics of the dielectric fluid (mineral oil or other).

Thus, once these parameters adjusted optimally for a given frequency, the interference field obtained can make zero the resultant pressure wave before contact with the walls of the transformer tank (ΣP = 0).

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1 est une vue partielle en perspective d'un transformateur visé par l'invention,
• la figure 2 est une vue partielle en perspective d'une barrière acoustique selon un mode de réalisation de l'invention agencée à l'intérieur de la cuve du transformateur selon la figure 1,
• la figure 3 montre schématiquement le fonctionnement d'une barrière acoustique selon l'invention,
• les figures 4 et 5 montrent en vue de coupe transversale en perspective un élément structurel de la barrière acoustique respectivement selon une première et deuxième variante de réalisation,
• les figures 6A et 6B montrent en perspective le montage d'un élément structurel de la barrière acoustique respectivement selon une première et deuxième variante de réalisation,
• la figure 7 est une vue partielle en perspective d'une barrière acoustique selon un autre mode de réalisation de l'invention,
• la figure 8 est une courbe représentative de l'efficacité d'une barrière acoustique selon l'invention.

Other advantages and characteristics will become more apparent on reading the detailed description given with reference to the following figures:

• the figure 1 is a partial perspective view of a transformer covered by the invention,
• the figure 2 is a partial perspective view of an acoustic barrier according to an embodiment of the invention arranged inside the transformer tank according to the figure 1 ,
• the figure 3 schematically shows the operation of an acoustic barrier according to the invention,
• the figures 4 and 5 show in perspective cross-sectional view a structural element of the acoustic barrier respectively according to a first and second variant embodiment,
• the Figures 6A and 6B show in perspective the mounting of a structural element of the acoustic barrier respectively according to a first and second variant embodiment,
• the figure 7 is a partial perspective view of an acoustic barrier according to another embodiment of the invention,
• the figure 8 is a curve representative of the effectiveness of an acoustic barrier according to the invention.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

The figure 1 shows a transformer 1 in which an acoustic barrier 2 according to the invention is arranged at a distance from the vertical walls 30A and from the top 30B of the vessel 3.

As visible, the transformer 1 comprises an active part by induction 4 immersed in dielectric oil (not shown) filling the tank 3.

In the embodiment shown in figure 2 the acoustic barrier 2 is of the passive type and consists of dielectric oil-tight hollow metal tubes arranged at regular intervals between them. More precisely, a regular pitch p1 separates two tubes 20 spaced apart from the same wall, a distance p2 separates two tubes 20 adjacent to the wedge between two vertical walls 30 and a distance p3 separates two adjacent tubes 20 between one of the vertical walls 30A. and a top wall 30B.

The hollow tubes 20 shown in figure 2 are of substantially rectangular cross-section. This substantially rectangular shape allows a good relaxation of the hollow tubes 20 and thus a good attenuation of low frequency noise.

According to the invention, the regular pitches thus define a space between two tubes 20 adapted to pass part of the pressure waves coming from the active part by induction 4 and propagated in the oil without introducing a phase shift thus constituting a group of wave. Each hollow tube 20 is adapted to be excited by its inner face 200, that is to say the one opposite the active part 4, by the other part of the waves coming from the active part and propagated in oil and reissue another group of waves in phase opposition. Thus, an interference field is created between these two groups of waves.

The figure 3 illustrates the creation of an interference field by the phase inversion between the wave portion 01 from the incident waves and passing through the barrier 2 and the portion 02 reemitted by each of the hollow tubes 20: there is thus a compensation between the two sources Q +, Q- of created virtual waves. By adjusting the parameters, which are the geometry and the material of the tubes 20, the step of the barrier 2, the distance separating the barrier 2 from the walls 30A, 30B of the tank 3, the characteristics of the oil, it is possible to completely cancel the resultant of the pressure waves before contact with the walls (ΣP = 0).

The dimensions of the hollow tubes 20 and the value of the regular spacing pitches are preferably adapted so that the barrier 2 has a total coverage of the periphery of the active part by induction 4 at the distance D from the vertical walls 30A and from the top 30B .

Depending on the characteristics of the desired waves, the hollow tubes 20 according to the invention, which are impervious to dielectric oil, may be filled either with a light fluid (gas) or with a flexible material (foam or elastomer).

• le tube creux 20 à section rectangulaire de la figure 4 est un tube plié soudé dont l'étanchéité est réalisée par deux plaques soudées 21, 22 et qui est rempli d'un gaz,
• les tubes creux 20 à section rectangulaire de la figure 5 sont des tubes extrudés dont l'étanchéité est réalisée par deux dispositifs 21, 22 formant des flasques de fixation pour tous les tubes et qui sont remplis d'un gaz.

Two alternative embodiments of hollow tubes with a rectangular section are shown in FIGS. figures 4 and 5 :

• the hollow tube 20 with rectangular section of the figure 4 is a folded welded tube whose sealing is achieved by two welded plates 21, 22 and which is filled with a gas,
• the hollow tubes 20 with rectangular section of the figure 5 are extruded tubes whose sealing is performed by two devices 21, 22 forming fastening flanges for all the tubes and which are filled with a gas.

In order to obtain a significant reduction of the noise at low frequencies, related to the transfer of acoustic energy by the dielectric oil, it is advantageous to mount the hollow tubes 20 in the tank 3 via vibratory decoupling means.

• les tubes creux 20 de la figure 6A sont fixés par l'intermédiaire de plots 50 à un cadre rigide 6 agencé dans la cuve 3,
• les tubes creux 20 de la figure 6B sont fixés par l'intermédiaire de lames flexibles 51 à un cadre rigide 6 agencé dans la cuve 3. Un tel montage est avantageux dans la mesure où il permet de pouvoir manipuler des ensembles modulaires d'une pluralité de tubes 20 et donc simplifie la mise en place de la barrière acoustique dans la cuve de l'appareillage.

Two alternative embodiments of assembly by means of vibratory decoupling means are shown in FIGS. Figures 6A and 6B :

• the hollow tubes 20 of the Figure 6A are fixed by means of studs 50 to a rigid frame 6 arranged in the tank 3,
• the hollow tubes 20 of the Figure 6B are fixed by means of flexible blades 51 to a rigid frame 6 arranged in the vessel 3. Such an assembly is advantageous insofar as it makes it possible to be able to handle modular assemblies of a plurality of tubes 20 and thus simplifies the setting in place of the acoustic barrier in the tank of the apparatus.

An advantage of mounting the acoustic barrier 2 on an intermediate fixing frame 6 is the simplicity of implementation.

Another embodiment of the acoustic barrier 2 according to the invention is shown in FIG. figure 7 the hollow tubes 20 are here cylindrical and fixed on rails 7 by means of hooks 52 of compressible material making it possible to perform the vibratory decoupling between tubes 20 and rails 7.

Acoustic tests were successfully carried out on a distribution transformer of 160 kVA made on a reduced scale with a passive acoustic barrier according to the invention.

Other acoustic tests have been successfully performed on a 40 MVA power transformer produced on an industrial scale with a passive acoustic barrier according to the invention.

In figure 8 , the curve represents the acoustic attenuation of the barrier 2 in dB according to the invention as a function of the noise frequencies emitted by the active part by induction 4: it is clearly seen that the acoustic barrier 2 allows an effective attenuation of the noise beyond with a frequency of 100 Hz.

Other improvements and alternative embodiments may be envisaged without departing from the scope of the invention.

Thus, it is possible to envisage tubes of different sections: square, rectangular, cylindrical, ....

One can also consider a connection between the internal volume of the tubes with a medium outside the transformer tank, or a internal environment to the tank of the electrical equipment, but separated from the dielectric fluid.

An acoustic barrier partially surrounding the inside of a HV or MV equipment tank can be envisaged, in particular in the case where the active part by induction emits waves in a preferred direction. Thus, it is conceivable to implement an acoustic barrier according to the invention only facing the side faces of the electrical equipment tank.

Depending on the architecture of the electrical equipment, we can achieve the acoustic barrier according to the invention on the bottom of the tank. In practice, in the current architectures of electrical equipment, such as transformers, it is quite possible to envisage a solution of double dielectric fluid partitioning / bottom of the tank / air / box which is satisfactory for the attenuation of the noises towards the bottom. of the tank.

Claims (8)

1. High- or medium-voltage equipment (1) comprising an induction-activated portion, a tank (3) surrounding the active portion (4) and filled with a dielectric fluid, and passive acoustic reduction means (2, 20) for reducing acoustic waves coming from the active portion and propagating in the dielectric fluid, wherein said acoustic reduction means being hollow structural elements (20), characterize in that:

   passive acoustic reduction means make it possible to divide the propagated waves into two groups of waves of opposite phase (01, 02) that interfere with each other, the passive acoustic reduction means being further leaktight to the dielectric fluid contained in the tank, the elements being arranged to be regularly spaced apart and to form a barrier (2) at a distance from the walls of the tank, the space between two adjacent structural elements being adapted to let through a fraction of the waves (01) coming from the active portion and propagating in the fluid without introducing any phase shift, thereby constituting one of the two wave groups, each structural element being adapted to be excited via its inside face (200) by the other fraction (02) of the waves coming from the active portion and propagating in the fluid, and to re-emit the other wave group in phase opposition, in a zone that is at a distance from the walls of the tank so as to at least limit the amplitude of the waves before they make contact with said walls.
2. Equipment (1) according to claim 1, wherein the structural elements include tubes (20) of constant inside section along their height, each tube being closed at each of its ends by a device that is leaktight (20, 21).
3. Equipment (1) according to claim 1 or claim 2, wherein the structural elements are mounted inside the tank by vibration decoupling means (50, 51, 52).
4. Equipment (1) according to claim 3, wherein the structural elements are fastened to a rigid frame (6) by vibration decoupling means.
5. Equipment according to any one of claims 2 to 4, wherein the surface area of the structural elements (20) is not less than two-thirds of the surface area of the barrier (2).
6. Equipment according to any preceding claim constituting a transformer.
7. Equipment according to any one of claims 1 to 6, constituting an induction coil.
8. Equipment according to any of the claims 1 to 8, wherein the dielectric fluid is oil, said hollow (20) and sealed structural elements being filled with a gas or foam or an elastomer.

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