Multi-channel active noise control system for power transformer

A control system and multi-channel technology, applied in the field of multi-channel active control systems, can solve the problems of large amount of calculation, limited installation space, and inability to increase the volume of equipment, etc., to achieve good channel expansion, good control effect, and favorable The effect of ventilation and heat dissipation

Inactive Publication Date: 2011-10-05

NANJING UNIV

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Problems solved by technology

In order to effectively shield the noise emitted by the transformer, it is often required that the sound insulation and sound absorption layer be fully enclosed, which will cause the problem of ventilation and heat dissipation of the transformer

The existing solution is to set an air inlet with a certain area and install a muffler at the air inlet, but this will cause poor low-frequency noise control effect

In this case, it can only be solved by thickening the sound insulation and sound absorption layer and lengthening the muffler. However, under certain site conditions, the surrounding space requires a high volume of equipment, so that it is impossible to increase the volume of the equipment and improve the sound insulation effect.

Therefore, the disadvantages of this type of noise control technology for power transformers using sound insulation and sound absorption layers are: 1. The low-frequency noise control effect of transformers is not good; 2. The ventilation and heat dissipation effects are not good in actual use and are limited by the surrounding installation space

In the aspect of transformer noise active control source, an inertial shaker was proposed (X.Liet al..Tuneable inertia shakers for active control, International Journal of Acoustics and Vibration, 6(4), 180-184, 2001); In terms of active control algorithms, a waveform synthesis algorithm was proposed (X.Qiu et al., Analgorithm for active control of transformer noise with on-line cancellation path modeling based on the perturbation method, Journal of Sound and vibration, 240(4), 647-665 , 2001; X.Qiu et al., Awaveform synthesis algorithm for active control of transformer noise: implementation, AppliedAcoustics, 63, 467-479, 2003); although scholars have proposed a distributed transformer based on a single-channel feedback control control unit Noise active control system (P. Micheau et al, Implementation of decentralized active control of powertransformer noise, First European Forum on Ma...

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Abstract

The invention discloses a multi-channel active noise control system for a power transformer which can separately or simultaneously reduce the components approximate to 100Hz, 200Hz and 300Hz in noises of the power transformer and has high degree of automation and a good noise reduction effect. Compared with the noise reduction method of the traditional transformer, the system has a good noise reduction effect on the noise peak approximate to 100Hz, 200Hz and 300Hz; under an ideal condition, the magnitude order of the environmental noise can be reduced to at the microphone; the system manages the input and output of signals in a distributed manner by using a quad-channel signal condition/driving module, has good passageway expansibility and is convenient to realize and maintain; a man-machine interactive module facilitates to manage operation and exchange data; and in addition, the multi-channel active noise control system is less affected by the installation space of the field and is beneficial to the ventilation and heat dispersion of the power transformer.

Application Domain

Transformers/inductances noise damping

Technology Topic

Environmental noiseTransformer +11

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Examples

Experimental program(1)

Example Embodiment

[0026] Embodiment: The noise of the power transformer to be controlled is measured, and the present invention can be used if the noise spectrum of the power transformer has obvious line spectrum components near 100 Hz, 200 Hz, and 300 Hz.

[0027] First, measure the sound field distribution of the line spectrum of power transformer noise around 100Hz, 200Hz, and 300Hz and determine the amount of noise reduction that needs to be achieved. Then, based on the measured data and the number of control sources to be implemented, the position and individual The number is optimized. The optimization methods used can be found in existing publications (Translated by Yi Chuijie, Active Control of Noise and Vibration, Science Press, 2002; Chen Ke'an, Ma Yuanliang, Adaptive Active Noise Control-Principles, Algorithms and Implementation, published by Northwestern Polytechnical University Society, 1993).

[0028] Such as Figure 5 As shown, the power transformer active noise control system of this embodiment includes a microphone 1, a control source 2, a reference signal sensor 3, and a console 4. The microphone 1 and the control source 2 are located above and around the transformer 8, and the reference signal sensor 3 Installed on the surface of the transformer 8. The microphone 1, the control source 2 and the reference signal sensor 3 are all connected to the console 4. Among them, the console 4 is composed of a signal condition/drive module 5, a multi-channel periodic noise adaptive control module 6, and a human-computer interaction module 7.

[0029] The microphone adopts electret microphones. In this example, the number is 16, the sensitivity is 24mV/Pa, and they are placed on the side away from the transformer 8 outside the envelope formed by the control source.

[0030] The control source adopts loudspeakers, the number in this example is 16, which are evenly distributed above and around the transformer 8. The loudspeaker is a cuboid closed box loudspeaker with a rated power of 60W. The surface of the box installation unit is square with a side length of 23cm and a box height of 18cm.

[0031] The reference signal sensor uses an accelerometer with a sensitivity of 50mV/g, installed on the surface of the transformer, and directly connected to the multi-channel periodic noise adaptive control module on the console.

[0032] Signal Condition/Drive Module In this example, 4 groups are used. Each group of modules is responsible for the amplification and filtering of the signals collected by the 4 microphones and the driving of the 4 control sources, corresponding to each other. The amplitude of the input electrical signal of the conditioner is normal within the range of 30~75mV, and the corresponding indicator light shows green; less than 30mV is weak and the indicator light does not light; higher than 75mV is overload, and the indicator light shows red. The maximum gain of the conditioner is 24dB. The normal range of the input electrical signal of the drive circuit is 20~500mV, the maximum gain is 26.5dB, and the maximum output power is 30W.

[0033] The multi-channel periodic noise adaptive control module is composed of two digital signal processing boards. The main frequency of the processor is 450M Hz, the computing capacity is 2700 MFLOPS, and the memory is 5Mb. The module has 17 inputs (16 channels of microphones collect error signals from the signal condition/drive module and 1 channel of reference signal sensors to collect reference signals) and 16 outputs to drive 16 control sources. The maximum input amplitude of the error signal is 2.8V, the maximum dynamic range is 112dB, and the sampling frequency is 48k Hz; the maximum input amplitude of the reference signal is 200mV; the maximum amplitude of the output signal is 2.8V.

[0034] The human-computer interaction module exchanges data with the multi-channel periodic noise adaptive control module through the serial port. The administrator sends instructions to the multi-channel periodic noise adaptive control module through the control panel displayed on the computer touch screen in the human-computer interaction module to operate the power transformer active noise control system in this embodiment and observe the control effect. After the active noise control system in this embodiment is turned on, the noise control effect measured at 16 error microphones is as follows Figure 7 As shown, it can be found that the noise components of 100Hz, 200Hz, and 300Hz are all reduced, and the noise reduction is greater than 10dB.

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Classification and recommendation of technical efficacy words

Good control effect

Multi-channel active noise control system for power transformer

AI-Extracted Technical Summary

Problems solved by technology

Abstract

Image

Examples

Example Embodiment

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Description & Claims & Application Information

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