CN101937770B - Low-noise power capacitor using interior compressible space structure of capacitor - Google Patents

Abstract

The invention discloses a low-noise power capacitor using an interior compressible space structure of a capacitor, wherein a combined structure with a compressible space including a sealing airbag and compressible gas in the airbag is arranged at the lower part inside a box body of the conventional capacitor. After the combined structure is installed, a capacitor core is arranged in the box body of the capacitor, and vacuumizing and oil injection are carried out to complete the manufacture of the whole capacitor. Compared with the conventional capacitor, the invention has the advantages of great reduction of noise radiation quantity, low cost, simple process and easy production and manufacture without influencing security stability of the power capacitor.

Description

Adopt the low-noise power capacitor of the inner compressible space structure of capacitor

Technical field

The present invention relates to the high voltage electric power equip ment field of noise control, particularly adopt the low-noise power capacitor of inner compressible space structure.

Background technology

The audible noise problem of parallel connection in the HVDC converter substation, filtering and PLC capacitor device is serious at present, mainly is because the noise of the separate unit power capacitor of wherein being installed causes more greatly.The method that reduces this power capacitor noise at present mainly contains following several kinds:

1) international conference on large HV electric systems has been recommended several kinds of noise reduction measures that power capacitor is inner, as: avoid the natural frequency of vibration of capacitor and strengthen capacitor body intensity etc.But avoid the natural frequency of vibration of capacitor, need to change original project organization, have very high risk, feasibility poor; And strengthen the intensity of inner fuse, can cause its radiating effect variation, thereby influence the life-span of power capacitor.

2) domestic some R&D institutions and producer have also proposed some and have reduced the measure of capacitor noises, as: be coated with at capacitor case and wrap up in material or to add elastic damping etc. in capacitor inside.Power capacitor is a high-tension apparatus, its surface smear or lapping very unfavorable to capacitor heat radiation, can Yin Wendu when operation too high and have an accident; Basically do not act on and add elastic damping in capacitor inside yet.

Summary of the invention

The present invention provides a kind of design of adopting the low-noise power capacitor of inner compressible space structure; Can be used in HVDC converter substation parallel connection, filtering and the PLC capacitor device; Significantly reduce than conventional capacitor noise amount of radiation; And this power capacitor is with low cost, technology simple, be easy to production and manufacturing, and does not influence the security and stability of power capacitor.

Technical scheme of the present invention is achieved in that

Comprise conventional capacitor, one inner compressible space structure is installed, comprise the air layer in pressure bladder and the air bag, play the effect of absorption capacitor internal vibration in the bottom of the casing of conventional capacitor.This structure also can be installed in the casing top of conventional capacitor.

Pressure bladder is a sealing pillow type air bag; Length and width are respectively than the length and the wide weak point 5～50mm of conventional capacitor casing bottom surface; Compressible gas layer thickness 20～50mm in the air bag; Air bag wall thickness 4～10mm, the material of airbag wall and capacitor oil have compatibility and have elasticity and sealing preferably, and need during capacitor life-span, meet the demands by degree of aging.The material of air bag is fluorubber or has certain elasticity and satisfy the plastics of the solubility of capacitor oil that the structure of airbag wall is the tension flexible layer wall of the anti-hauling type of embedded nylon.

The air that the material of compressible gas is, its pressure are 1～1.3 atmospheric pressure, and air layer thickness is 20～50mm, adopt other gas also passable.

The present invention adopts the low-noise power capacitor of inner compressible space structure to compare with the power capacitor of routine, the conservative 10dB that is estimated as of noise reduction.

Description of drawings

Fig. 1 structural representation of the present invention;

Below in conjunction with accompanying drawing content of the present invention is done further explain.

Embodiment

With reference to shown in Figure 1, the present invention installs an inner compressible space structure in casing 1 bottom of existing conventional electric power capacitor, and this locations of structures is in the bottom of the casing 1 of conventional capacitor; If there are two enough big holes to supply lead-in wire to pass on the inner compressible space structure, this structure also can be installed in the top in the conventional capacitor casing 1.

Can be according to the installation site of power capacitor, analysis stream is crossed frequency and the spectral characteristic of the noise that produces of the electric current of capacitor, reasonably designs inner compressible space thickness of structure and makes.After inner compressible space structure was installed in the bottom of conventional capacitor casing, can be according to the manufacturing process of conventional capacitor: capacitor body is installed, and welding top shell vacuumizes, and the manufacturing of whole low-noise power capacitor is accomplished in oiling etc. like this.This low-noise power capacitor is installed on the capacitor device in the current conversion station, and when its work, the vibration that inner fuse 5 vibrations of capacitor produce through the absorption of inner compressible space structure 3,4, is radiated extraneous noise level and reduces greatly.

Adopt the technical basis of the low-noise power capacitor of inner compressible space structure

Because the pressure effect that the vibration of fuse changes to capacitor oil; The flowable of liquid makes that the suffered power of compressible space element all is normal direction; And it is irrelevant with its shape; And any point all can receive the influence of compressible space element in the oil, therefore, can be the equivalence of compressible space element very thin one deck around fuse.

Based on top analysis, gas and oily mechanical organ are connected, and the vibration of fuse arrives capacitor case through them, causes the vibration of shell, and therefore, the equivalent mechanical organ of gas, oil and shell is all connected.In the gas equivalence mechanical organ, gaseous mass can be ignored, and gas the main effect here is to reduce transfer of vibration, spring element k _gIt is its major parameter.Wet goods is imitated in the mechanical organ, compares and can ignore owing to comparing with the shell bending compression with gas, and mainly the form with quality exists in the system, and damping basically also can be ignored.In the capacitor case equivalence mechanical organ, spring element k _tThe parameter that expression shell rigidity is showed, mass elements m _tThe quality of expression shell and the air quality sum that acoustic radiation arranged, damping element can be ignored.The vibration velocity of fuse acts on capacitor oil and the compressible space element and finally passes to shell.To the mechanical component models of shell equivalence, be equivalent to have only the equivalence element of oil and shell to connect for the fuse of conventional capacitor, and the gas part that lacks.

Capacitor body produces vibration under the effect of electricity, ignore ectocine, can think that the mechanical impedance of fuse is certain, and under the certain situation of electric current, the vibration velocity that fuse produces is consistent.Promptly for conventional capacitor with install inner compressible space structure capacitive device fuse vibration velocity additional and be all V mutually _O

V _A, V _B, V _CBe respectively inner compressible space structure, the relative velocity of oil and shell.Because all particle velocities of mass elements are identical, V _BAnd V _CIdentical, in equiva lent impedance figure, all use V _CReplace, simultaneously, V _CThe vibration velocity of representing shell again is the emphasis that we pay close attention to.Z _gAnd Z _OtBe the result after mechanical impedance partly merges.

$Z_g=\frac{k_g}{\mathrm{j\ω}}$

$Z_{\mathrm{ot}}=\mathrm{j\ω}(m_o+m_t)+\frac{k_t}{\mathrm{j\ω}}$

1) conventional capacitor

V _C＝V _O

2) low noise capacitor

V _O＝V _A+V _C

F＝Z _gV _A＝Z _otV _C

$V_C=\frac{Z_g}{Z_{\mathrm{ot}}+Z_g}{V}_O$

3) prediction of inner compressible space element noise reduction

V _CBe the vibration that fuse is delivered to capacitor case, if consider the noise reduction L of inner compressible space element by desirable situation _ReductionFor

$L_{\mathrm{reduction}}=L_{\mathrm{regular}}-L_{\mathrm{CSC}}=20\lg \frac{p_{\mathrm{regular}}}{p_{\mathrm{CSC}}}$

$=20\lg \left|\frac{{\mathrm{\&upsi;}}_{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA0000025413150000011.png"\; state="\{\{state\}\}">C</figure-callout>}1}}{{\mathrm{\&upsi;}}_{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HDA0000025413150000011.png"\; state="\{\{state\}\}">C</figure-callout>}2}}\right|=20\lg \left|\frac{Z_{\mathrm{ot}}+Z_g}{Z_g}\right|$

$=20\lg |\frac{k_t-{\mathrm{\&omega;}}^2(m_o+m_t)}{k_g}+1|$

When ω is defined within the specific limits, k _gThe size of decision noise reduction.Formula can be reduced to

L _reduction＝20lg|CV ²-1|

Wherein, $C=\frac{{\mathrm{\&omega;}}^2(m_o+m_t)-k_{\mathrm{<figure-callout\; id="2"\; label="t\; NRTS"\; filenames="HDA0000025413150000011.png"\; state="\{\{state\}\}">t</figure-callout>}}}{{\mathrm{NRTS}}^{}}$

According to formula, noise reduction increases along with the increase of its volume.

Hence one can see that; When practical application, can be according to the installation site of power capacitor, analysis stream is crossed frequency and the spectral characteristic of the noise that produces of the electric current of capacitor; Reasonably design the size of inner compressible space structure, just can reach the purpose of the noise reduction that it is given off.

Case verification

(1) experiment condition and test point position

Experiment condition is: the electric current that flows through capacitor is 70A, and frequency is the harmonic frequency of 50Hz～600Hz.

(2) experimental result

Respectively the low-noise power capacitor that adopts inner compressible space structure and common power capacitor are carried out noise testing, and the comparative analysis test result.Experimental result is as shown in table 1.

Table 1 low noise capacitor and ordinary capacitor noise correction data

Can find out from table 1 noise testing data: for the low-noise power capacitor that adopts inner compressible space structure; Owing to adopted inner compressible space structure; And according to the frequency appropriate design of the electric current that flows through capacitor physical dimension; The noise level of its bottom surface is than more than the low 10dB of common power capacitor, and it is successful having confirmed to adopt the design of the low-noise power capacitor of inner compressible space structure.

Claims (3)

1. a low-noise power capacitor that adopts the inner compressible space structure of capacitor comprises conventional capacitor, it is characterized in that; A pressure bladder (3) is installed in bottom at the casing (1) of conventional capacitor, has compressible gas (4) in the air bag, and pressure bladder (3) is a pillow type air bag; Length and width are respectively than the length and the wide weak point 5～50mm of conventional capacitor casing (1) bottom surface; The interior compressible gas layer thickness of pressure bladder (3) 20～50mm, pressure bladder (3) wall thickness 4～10mm, compressible gas (4) is an air; Its pressure is 1～1.3 atmospheric pressure, and air layer thickness is 20～50mm.

2. according to the low-noise power capacitor of the inner compressible space structure of claims 1 described employing capacitor, it is characterized in that the material of pressure bladder (3) is fluorubber or rubber-like plastics.

3. according to the low-noise power capacitor of the inner compressible space structure of claims 1 described employing capacitor, it is characterized in that the structure of pressure bladder (3) wall is the tension flexible layer wall of the anti-hauling type of embedded nylon.

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