CN107768119B - Active noise reduction system of extra-high voltage power transformer - Google Patents
Active noise reduction system of extra-high voltage power transformer Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/33—Arrangements for noise damping
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
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- G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
- G10K2210/10—Applications
- G10K2210/109—Compressors, e.g. fans
Abstract
An active noise reduction system of an extra-high voltage power transformer is characterized in that a vibration sensor of a vibration signal acquisition module is attached to the transformer, a vibration signal of a shell of the transformer is acquired to serve as a reference signal, and a signal output by the vibration sensor is input into an audio chip through a gain-adjustable preamplifier; the sound pressure sensor is placed in a target noise reduction area, and a signal output by the sound pressure sensor is input into the audio chip through the gain-adjustable preamplifier and the filter; the audio chip collects noise signals, carries out A/D conversion and then transmits data to the DSP processor. The DSP processor receives data of the audio chip, the data are transmitted to the audio chip after being processed by the adaptive filtering algorithm, the data are input into the power amplifier after being subjected to D/A conversion, the loudspeaker is driven to generate noise reduction sound, the noise reduction sound and the transformer noise are mutually offset, and active noise reduction is achieved.
Description
Technical Field
The invention relates to a transformer noise processing system, in particular to an active noise reduction system of an extra-high voltage power transformer.
Background
With the expansion of the scale of the power grid, more and more large power transformers are installed near residences and public places, and the noise generated by the transformers seriously affects the work and life of workers in the station and residents around the station. The noise of the transformer body mainly comes from iron core vibration caused by silicon steel sheet magnetostriction during iron core excitation, and 2 times of power supply frequency is used as fundamental frequency. Due to the nonlinearity of the core material, the difference in the length of the magnetic path along the inner and outer frames of the core, and the like, the noise spectrum also contains integer frequency multiplication of the fundamental frequency. Thus, for a power supply with a frequency of 50Hz, transformer noise is low frequency noise with a frequency mainly centered at 100Hz and its integer multiples. The low-frequency noise can harm the health of human bodies and even influence the development of fetuses in the abdomen of pregnant women.
Transformer noise control is becoming an increasing concern. The noise reduction of the transformer is divided into two modes of passive noise reduction and active noise reduction. The passive noise reduction usually adopts a barrier to isolate noise, so that the noise reduction effect on high-frequency noise is obvious, and the noise reduction effect on low-frequency noise is not ideal. The main reason is that the wavelength of the low-frequency noise is relatively long, for example, the wavelength corresponding to 100Hz noise is about 3.4m, and the passive noise reduction needs a large size to produce a good noise reduction effect, which increases the cost and technical difficulty of the passive noise reduction. At present, an active noise reduction system mainly comprises a controller, a sound pressure sensor and a secondary sound source, and two control methods of feedforward control and feedback control are generally adopted. Feedback control generates a control signal by filtering the error signal, without the need for an additional reference input signal, which presents stability problems. The difference between the feedforward control and the feedback control is that the feedforward control system first obtains a reference signal, which is related to the primary sound source, thereby enhancing the stability of the active noise reduction system. Therefore, the accuracy of the reference signal is a key problem of a feedforward control mode, and is an important premise for ensuring a good noise reduction effect.
There have been some patents of transformer active noise reduction at home and abroad, but there still exist some problems in noise reduction effect and system stability:
(1) at present, an active noise reduction system adopting a feedforward control method obtains a reference signal through a sound pressure sensor, so that the reference signal inevitably contains transformer cooling fan noise, environmental noise and noise fed back by a secondary sound source. The high-frequency components in the cooling fan noise and the environmental noise can be filtered by the low-pass filter, but the low-frequency components in the cooling fan noise and the environmental noise and the feedback noise of the secondary sound source are difficult to filter;
(2) the reference signal collected by the sound pressure sensor of the existing active noise reduction system needs to be filtered firstly and then input into a control circuit, and the delay function of a filter is not beneficial to carrying out real-time noise reduction;
(3) the weak noise signals collected by the sensor can be input into the next stage circuit for processing after being amplified. Conventional active noise reduction systems use fixed gain amplifiers whose amplification is fixed. When the noise intensity is smaller, the amplitude of the noise signal output by the fixed gain amplifier is lower; when the noise intensity is large, the amplitude of the noise signal output by the fixed gain amplifier is high, and may exceed the range of the a/D sampling circuit, so that the stability of the active noise reduction system is low.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides an active noise reduction system of an extra-high voltage power transformer. The vibration signal of the transformer shell is collected by the vibration sensor to be used as a reference signal, the interference of cooling fan noise, environmental noise and secondary sound source feedback noise is eliminated, a relatively pure reference signal is obtained, and a filter circuit is omitted. The amplitude of the acquired signal is controlled to be always within a specified range through the gain-adjustable pre-amplification circuit. The invention can save the cost of the active noise reduction system, improve the signal processing speed and improve the stability of the system.
In order to achieve the purpose, the invention adopts the following technical scheme:
the active noise reduction system of the extra-high voltage power transformer comprises a vibration signal acquisition module, a sound pressure signal acquisition module, a signal processing module and a secondary sound source generation module. The vibration signal acquisition module and the sound pressure signal acquisition module are respectively connected with the signal processing module, and the signal processing module is connected with the secondary sound source generation module. The vibration signal acquisition module acquires a vibration analog signal of the transformer, the sound pressure signal acquisition module acquires a sound pressure analog signal, the acquired vibration analog signal and sound pressure analog signal are transmitted to the signal processing module through an audio signal wire to be subjected to AD conversion processing, the processed signal is transmitted to the secondary sound source generation module through the audio signal wire after being subjected to DA conversion, the secondary sound source generation module is composed of a power amplifier and a loudspeaker, the signal after the DA processing is transmitted to the loudspeaker through the power amplifier to transmit sound waves with the same amplitude and the opposite phase, the noise transmitted by the primary sound source is cancelled, and the noise reduction effect is achieved.
The vibration signal acquisition module comprises a vibration sensor and a first preamplifier. The vibration sensor is adhered to the transformer shell, and vibration data of the transformer shell are collected to be used as reference signals. The input end of the first preamplifier is connected with the vibration sensor, the signals collected by the vibration sensor are amplified, and finally the collected vibration analog signals are transmitted to the signal processing module from the output end of the first preamplifier.
The sound pressure signal acquisition module comprises a sound pressure sensor, a second preamplifier and a filter. The sound pressure sensor is placed in a target noise reduction area, and noise signals after noise reduction are collected to serve as error signals; the input end of the second preamplifier is connected with the sound pressure sensor, and a noise signal acquired by the sound pressure sensor is amplified; the input end of the filter is connected with the output end of the second preamplifier, high-frequency components in noise signals collected by the sound pressure sensor are filtered, and finally collected sound pressure analog signals are sent to the signal processing module from the output end of the filter.
The signal processing module comprises an audio chip and a DSP processor. The input end of the audio chip is connected with the output end of the filter, and the A/D sampling is carried out on the filtered sound pressure sensor signal; the DSP processor is connected with the output end of the audio chip; and the DSP processor processes the reference signal and the error signal, inputs the processed noise reduction signal into the audio chip for D/A conversion, and finally transmits the signal to the secondary sound source generation module.
The secondary sound source generation module comprises a power amplifier and a loudspeaker. The output end of the audio chip is directly connected with the input end of the power amplifier to amplify the noise reduction signal; the output end of the power amplifier is connected with the loudspeaker, and finally the loudspeaker is driven to generate noise reduction sound.
The vibration sensor is a sensor array composed of a plurality of acceleration sensors, wherein each acceleration sensor is fixed on a magnet. The vibration sensors are pasted on the transformer shell at equal intervals, and vibration signals of the transformer shell are directly collected to serve as reference signals.
The sound pressure sensor is a sensor array formed by a plurality of capacitance type MIC sensors, is positioned in a target noise reduction area, and collects noise signals as error signals.
The preamplifier adopts a MAX9814 chip.
The filter adopts an NE5532 operational amplifier, a third resistor and a fourth resistor are connected in series and then are connected with a third capacitor to form a first-order low-pass filter, a signal is amplified by the NE5532 operational amplifier and then is fed back through the fourth capacitor, at the moment, the fourth resistor and the third capacitor form a first-order low-pass filter, and the signal is amplified by the NE5532 operational amplifier again and then is output.
The DSP processor is a 6000 series DSP chip from TI corporation.
The loudspeaker is an array formed by a plurality of loudspeakers.
And the DSP processor processes the reference signal and the error signal by using a self-adaptive filtering algorithm and inputs the processed noise reduction signal into an audio chip for D/A conversion. The output end of the audio chip is connected with the input end of the power amplifier to amplify the noise reduction signal, and the output end of the power amplifier is connected with the loudspeaker to drive the loudspeaker to generate noise reduction sound.
The signal lines among the vibration sensor, the sound pressure sensor, the preamplifier, the filter, the audio chip, the DSP processor, the power amplifier and the mediant loudspeaker are all coaxial audio lines, and the joints are all RCA.
The invention collects the vibration signal of the transformer shell as the reference signal through the vibration sensor, eliminates the interference of the noise of the transformer cooling fan and the environmental noise to the measurement, simultaneously saves the filter circuit and improves the signal processing speed. The gain of the reference signal acquired by the vibration sensor and the gain of the error signal acquired by the sound pressure sensor are automatically adjusted by using the gain-adjustable preamplifier, so that the signals are amplified to a specified range, and the stability of the noise reduction system is improved
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a circuit diagram of a preamplifier of the invention;
FIG. 3 is a circuit diagram of a filter of the present invention;
FIG. 4 is a structural view of a vibration sensor of the present invention;
FIG. 5 is a graph of the output result of a fixed gain preamplifier circuit when the signal amplitude is greater than a threshold;
FIG. 6 is a graph of the output result of the gain adjustable preamplifier circuit of the invention;
FIG. 7 is a diagram of the results of the analysis of the vibration spectrum of the casing of the ultra-high voltage transformer acquired by the vibration sensor;
fig. 8 is a diagram of the analysis result of the extra-high voltage transformer noise spectrum acquired by the sound pressure sensor.
Detailed Description
The invention is further described with reference to the following figures and detailed description.
As shown in fig. 1, the active noise reduction system of the extra-high voltage power transformer includes a vibration signal acquisition module 1, a sound pressure signal acquisition module 2, a signal processing module 3, and a secondary sound source generation module 4. The vibration signal acquisition module 1 and the sound pressure signal acquisition module 2 are respectively connected with the signal processing module 3; the signal processing module 3 is connected with the secondary sound source generating module 4; the vibration signal acquisition module 1 acquires a vibration analog signal of the transformer, the sound pressure signal acquisition module 2 acquires a sound pressure analog signal, the acquired vibration analog signal and the sound pressure analog signal are transmitted to the signal processing module 3 through an audio signal wire to be subjected to AD conversion, and the processed signals are subjected to DA conversion and then transmitted to the secondary sound source generation module 4 through the audio signal wire.
The vibration signal acquisition module comprises a vibration sensor 5 and a first preamplifier 6; the vibration sensor 5 is adhered to the transformer shell, and vibration data of the transformer shell are collected to be used as reference signals; the input end of the first preamplifier 6 is connected with the vibration sensor 5, amplifies the signal collected by the vibration sensor 5, and finally transmits the collected vibration analog signal to the signal processing module 3 from the output end of the first preamplifier 6.
The sound pressure signal acquisition module comprises a sound pressure sensor 7, a second preamplifier 8 and a filter 9. The sound pressure sensor 7 is placed in a target noise reduction area, and noise signals after noise reduction are collected to serve as error signals; the input end of the second preamplifier 8 is connected with the sound pressure sensor 7, and amplifies a noise signal collected by the sound pressure sensor 7; the input end of the filter 9 is connected with the output end of the second preamplifier 7, so as to filter high-frequency components in the noise signal collected by the sound pressure sensor 7, and finally, the collected sound pressure analog signal is sent to the signal processing module 3 from the output end of the filter 9.
The signal processing module 3 comprises an audio chip 10 and a DSP (digital signal processor) 11, wherein the input of the audio chip 10 is connected with the output end of the filter 9, and the filtered sound pressure sensor signal is subjected to A/D (analog/digital) sampling; the DSP processor 11 is connected with the output end of the audio chip 10; the DSP processor 11 processes the reference signal and the error signal, inputs the processed noise reduction signal to the audio chip 10 for D/a conversion, and finally transmits the signal to the secondary sound source generation module 4.
The secondary sound source generation module 4 comprises a power amplifier 12 and a loudspeaker 13, wherein the output end of the audio chip 10 is directly connected with the input end of the power amplifier 12 to amplify the noise reduction signal; the output end of the power amplifier 12 is connected to the speaker 13, and finally drives the speaker 13 to generate noise reduction sound.
The vibration sensor 5 is a sensor array of a plurality of acceleration sensors each fixed to a magnet, as shown in fig. 4.
The first preamplifier 6 is a gain adjustable amplifier, which can adjust the gain of the amplifier in real time according to the amplitude of the input noise signal, the circuit schematic diagram is shown in fig. 2, the core of the first preamplifier 6 is a MAX9814 gain adjustable operational amplifier, the signal is input from the 8 th pin to the 6 th pin for output, and the amplification factor of the whole circuit can be changed by changing the voltage of the MICBIAS terminal. When the amplitude of the input noise signal is smaller than a set value, the DSP processor controls the relay to enable the MICBIAS port of the amplifying circuit to be connected with a high level, at the moment, the amplifying circuit is in a high-gain amplifying mode, when the amplitude of the input noise signal is larger than the set value, the DSP processor controls the relay to enable the MICBIAS port of the amplifying circuit to be connected with a low level, at the moment, the amplifying circuit is in a low-gain amplifying mode, and the amplitude of the signal acquired by the sampling circuit can be always in a specified range through the gain-adjustable amplifier.
The first preamplifier 6 and the second preamplifier 8 are identical in structure. As shown in FIG. 2, in the MAX9814 chips of the first preamplifier 6 and the second preamplifier 8, the 1 st pin is connected in series with the first capacitor C17 of 470nF and then grounded, the 2 nd pin, the 5 th pin and the 10 th pin are connected with VCC, the 3 rd pin is connected in series with the second capacitor C2 of 2.2uF and then grounded, the 4 th pin and the 11 th pin are blank pins, the 6 th pin is connected in series with the high pass filter composed of the fifth capacitor C5 and the sixth resistor R6, the 7 th pin and the 9 th pin are grounded, the 8 th pin is connected in series with the seventh capacitor C7 of 0.1uF and then connected with the input end of the preamplifier, the 12 th pin is connected in series with the sixth capacitor C6 of 0.47uF and then connected with the fifth resistor R5 of 1M omega and then connected with the input end of the preamplifier, and the 14 th pin is connected with the midpoint of the voltage dividing circuit composed of the first resistor R1 and the second resistor R2. When the amplitude of the input noise signal is smaller than a set value, the DSP processor controls the MICBIAS port to access a high level, so that the amplifying circuit works in a high-gain amplifying mode; when the amplitude of the input noise signal is larger than a set value, the DSP processor controls the MICBIAS port to be connected with a low level, so that the amplifying circuit works in a low gain amplifying mode.
The sound pressure sensor 7 is a sensor array composed of a plurality of capacitance type MIC sensors.
The filter circuit is shown in fig. 3 and comprises an operational amplifier NE5532 and two first-order low-pass filters. The third resistor R3 and the fourth resistor R4 are connected in series and then connected with the third capacitor C3 to form a first-order low-pass filter, the signal is amplified by the operational amplifier NE5532 and then fed back through the parallel fourth capacitor C4, at this time, the fourth resistor R4 and the third capacitor C3 form a first-order low-pass filter, and the signal is amplified again by the operational amplifier NE5532 and then output. The noise signal may be filtered of high frequency components when passing through the filter.
The audio chip 10 mainly functions to implement a/D conversion and D/a conversion, convert analog noise signals into digital signals, send the digital signals to the DSP, receive the digital signals processed by the DSP, convert the digital signals into analog signals, and input the analog signals to the power amplifier.
The power amplifier 7 is mainly used for amplifying weak noise reduction signals and then driving the loudspeaker 13 to sound, the input end of the power amplifier 12 is connected with the output end of the audio chip 10, and the output end of the power amplifier 12 is connected with the input end of the loudspeaker 13.
The loudspeaker 13 is an execution unit of the whole system, and plays the noise reduction signal amplified by the power amplifier to cancel the noise of the transformer.
The DSP processor 11 is a control unit of the whole system, and controls the sampling of the audio chip 10, performs adaptive filtering processing on the received signal, and controls the audio chip 10 to play a noise reduction signal, thereby implementing active noise reduction.
The signal lines among the vibration sensor 5, the sound pressure sensor 7, the first preamplifier 6, the second preamplifier 8, the filter 9, the audio chip 10, the DSP processor 11, the power amplifier 12 and the loudspeaker 13 are all coaxial audio lines, and the connectors are RCA connectors, so that signals can be smoothly transmitted in a strong electric field of an extra-high voltage transformer substation, and the anti-interference capability of the system is improved.
When the signal amplitude is larger than the signal limit, the output signal after passing through the two pre-amplifiers 6, 8 with fixed gain is as shown in fig. 5. The preamplifiers 6 and 8 with adjustable gains are adopted for control, and the output results of the collected signals after passing through the preamplifiers 6 and 8 are shown in FIG. 6; it can be seen that when the signal amplitude is greater than the signal limit, the amplifier signal with fixed gain is distorted, while the signal is not distorted by the gain- adjustable preamplifiers 6, 8 of the present invention.
The normalized frequency spectrum analysis result of the vibration signal at a certain point of the shell of the extra-high voltage transformer acquired by the vibration sensor is shown in fig. 7. The signals shown in fig. 7 are directly acquired, amplified, and unfiltered vibration signals. The signals are mainly concentrated on 100Hz and frequency multiplication thereof, and the signals of the transformer body are lower than 600Hz and mainly 200 Hz. Fig. 8 shows the analysis result of the ultra-high voltage transformer noise spectrum acquired by the sound pressure sensor. The signal shown in fig. 8 is a noise signal after collection, amplification and filtering, and the filter filters out high-frequency components greater than 1kHz, but broadband noise generated by a fan and the environment in the range of 1kHz still exists, and the result reflects the comprehensive effect of the noise of the transformer body, the noise of the fan and the noise of the environment.
Claims (3)
1. An active noise reduction system of an extra-high voltage power transformer is characterized in that: the active noise reduction system of the extra-high voltage power transformer comprises a vibration signal acquisition module (1), a sound pressure signal acquisition module (2), a signal processing module (3) and a secondary sound source generation module (4); the vibration signal acquisition module (1) and the sound pressure signal acquisition module (2) are respectively connected with the signal processing module (3); the signal processing module (3) is connected with the secondary sound source generating module (4); the vibration signal acquisition module (1) acquires a vibration analog signal of the transformer, the sound pressure signal acquisition module (2) acquires a sound pressure analog signal, the vibration analog signal and the sound pressure analog signal are sent to the signal processing module (3) through an audio signal wire for AD conversion, and the processed signals are sent to the secondary sound source generation module (4) through the audio signal wire after DA conversion;
the vibration signal acquisition module (1) comprises a vibration sensor (5) and a first preamplifier (6); the vibration sensor (5) is adhered to the transformer shell, and vibration data of the transformer shell are collected to be used as reference signals; the input end of the first preamplifier (6) is connected with the vibration sensor (5), amplifies signals collected by the vibration sensor (5), and transmits collected vibration analog signals to the signal processing module (3);
the sound pressure signal acquisition module comprises a sound pressure sensor (7), a second preamplifier (8) and a filter (9); the sound pressure sensor (7) is placed in a target noise reduction area, and noise signals after noise reduction are collected to serve as error signals; the input end of the second preamplifier (8) is connected with the sound pressure sensor (7) to amplify the noise signal collected by the sound pressure sensor (7); the input end of the filter (9) is connected with the output end of the second preamplifier (8), high-frequency components in noise signals collected by the sound pressure sensor (7) are filtered, and finally collected sound pressure analog signals are sent to the signal processing module (3) from the output end of the filter (9);
the signal processing module (3) comprises an audio chip (10) and a DSP (digital signal processor) processor (11); the input of the audio chip (10) is connected with the output ends of the filter (9) and the first preamplifier (6), and the A/D sampling is carried out on the filtered sound pressure sensor signal and the filtered vibration sensor signal; the DSP processor (11) is connected with the output end of the audio chip (10); the DSP processor (11) processes the reference signal and the error signal, inputs the processed noise reduction signal into the audio chip (10) for D/A conversion, and finally transmits the signal to the secondary sound source generation module (4);
the secondary sound source generating module (4) comprises a power amplifier (12) and a loudspeaker (13); the output end of the audio chip (10) is directly connected with the input end of the power amplifier (12) to amplify the noise reduction signal; the output end of the power amplifier (12) is connected with the loudspeaker (13), and finally the loudspeaker (13) is driven to generate noise reduction sound;
the active noise reduction system of the extra-high voltage power transformer takes a transformer shell vibration signal acquired by a vibration sensor (5) as a reference signal, and acquires a signal subjected to noise reduction in a target noise reduction area by using a sound pressure sensor (7) as an error signal; a reference signal is input into a DSP (11) through a first preamplifier (6) with adjustable gain, and an error signal is input into the DSP (11) through a second preamplifier (8) with adjustable gain and a filter (9); the DSP (11) processes the amplified reference signal and the error signal by using a self-adaptive filtering algorithm, inputs the processed noise reduction signal into the power amplifier (12) to be amplified, drives the loudspeaker (13) to generate noise reduction sound, and cancels the noise of the transformer, thereby realizing active noise reduction.
2. The active noise reduction system of an extra-high voltage power transformer of claim 1, characterized in that: in the first preamplifier (6) and the second preamplifier (8), the 1 st pin of a MAX9814 chip is connected with a first capacitor C17 of 470nF in series and then grounded, the 2 nd pin, the 5 th pin and the 10 th pin are connected with VCC, the 3 rd pin is connected with a second capacitor C2 in series and then grounded, the 4 th pin and the 11 th pin are null pins, the 6 th pin is connected with a high-pass filter consisting of a fifth capacitor C5 and a sixth resistor R6 in series, the 7 th pin and the 9 th pin are grounded, the 8 th pin is connected with a seventh capacitor C7 in series and then connected with the input end of the preamplifier, the 12 th pin is connected with a sixth capacitor C6 in series and then connected with a fifth resistor R5 in series and then connected with the input end of the preamplifier, and the 14 th pin is connected with the midpoint of a voltage division circuit consisting of a first resistor R1 and a second resistor R2; when the amplitude of the input noise signal is smaller than a set value, the DSP processor controls the MICBIAS port to access a high level, so that the preamplifier works in a high-gain amplification mode; when the amplitude of the input noise signal is larger than a set value, the DSP processor controls the MICBIAS port to be connected with a low level, so that the amplifying circuit works in a low gain amplifying mode.
3. The active noise reduction system of an extra-high voltage power transformer of claim 1, characterized in that: the filter consists of an operational amplifier NE5532 and two first-order low-pass filters; the third resistor R3 and the fourth resistor R4 are connected in series and then connected with the third capacitor C3 to form a first-order low-pass filter, the signal is amplified by the NE5532 and then fed back by the parallel fourth capacitor C4, at the moment, the fourth resistor R4 and the third capacitor C3 form a first-order low-pass filter, and the signal is amplified by the operational amplifier NE5532 again and then output; when the noise signal passes through the first-order low-pass filter formed by the fourth resistor R4 and the third capacitor C3, the high-frequency component in the noise signal is filtered.
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| CN109238443A (en) * | 2018-08-01 | 2019-01-18 | 中科振声（苏州）电子科技有限公司 | A kind of vibration noise intelligence reply system and a kind of vibration noise intelligence countermeasure |
| CN108827450B (en) * | 2018-08-30 | 2024-01-05 | 重庆盾琪科技有限公司 | Noise detection circuit |
| CN110246482B (en) * | 2019-06-12 | 2021-09-03 | 深圳供电局有限公司 | Noise reduction device and control method thereof |
| CN110277084A (en) * | 2019-07-10 | 2019-09-24 | 上海博纳杰陈电气有限公司 | A kind of transformer silencer using active noise reduction |
| CN111063528B (en) * | 2019-11-25 | 2021-08-31 | 深圳供电局有限公司 | Active noise reduction equipment of transformer and transformer noise on-line monitoring system |
| CN112652289A (en) * | 2020-12-11 | 2021-04-13 | 西安艾科特声学科技有限公司 | Fire fighting truck cab local space active noise control system and method |
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| CN103971908A (en) * | 2014-05-06 | 2014-08-06 | 国家电网公司 | Transformer noise suppression method |
| CN105606933A (en) * | 2016-01-13 | 2016-05-25 | 中国南方电网有限责任公司超高压输电公司 | Vibration-noise-based on-line monitoring system of converter transformer |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103971908A (en) * | 2014-05-06 | 2014-08-06 | 国家电网公司 | Transformer noise suppression method |
| CN105606933A (en) * | 2016-01-13 | 2016-05-25 | 中国南方电网有限责任公司超高压输电公司 | Vibration-noise-based on-line monitoring system of converter transformer |
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