A substation active noise control system for a semi-enclosed sound-insulating structure

Abstract

The application discloses a substation active noise control system of semi-closed sound insulation structure, which combines passive sound insulation and active noise control technology, and comprises a semi-closed sound insulation structure, sound-absorbing material, a reference microphone, an error microphone, a secondary sound source and an adaptive control system; an opening is arranged on a side wall of the semi-closed sound insulation structure; the sound-absorbing material is arranged on the inner wall surface of the wall corresponding to the opening side of the semi-closed sound insulation structure, the sound-absorbing material is arranged in a gap mode corresponding to the inner wall surface, and the sound-absorbing material adopts a single-layer parallel type micro-perforated sheet of a sound-absorbing structure; the reference microphone is used for collecting a primary noise signal of a transformer at the opening; the error microphone is used for collecting a noise signal after cancellation; the secondary sound source is used for emitting a cancellation sound signal under the control of the adaptive control system; the adaptive control system receives the primary noise signal and generates a noise cancellation signal for eliminating noise by using an adaptive algorithm according to the primary noise signal; after digital-analog conversion, the output power of the secondary sound source is controlled, so that the substation noise can be effectively controlled.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power equipment noise control, and particularly relates to a sub-closed sound insulation structure substation active noise control system. BACKGROUND

[0002] With the advancement of urbanization and the improvement of the quality of life of residents, the demand for electricity in cities is growing rapidly, and power users are increasingly demanding electricity. Some substations are located in the city center and densely populated areas, which has made the noise pollution problem of substations receive more and more social attention.

[0003] The urban substations are generally arranged in a full indoor or semi-indoor manner, and usually take measures such as sound absorption, sound insulation and vibration reduction to reduce the noise intensity, mainly aiming at the high-frequency noise in the audible frequency spectrum. However, for the low-frequency noise generated by the main transformer, due to its long wavelength, strong penetration and diffraction ability, in order to achieve good noise reduction effect, the thickness of the sound absorption material or the weight and height of the partition must be increased in the traditional passive noise control mode. Not only is the investment cost high, but also the occupied space is large. After taking measures such as closed isolation, the noise in the equipment room will be larger, which will affect the operation and maintenance personnel entering the substation, and the completely closed sound insulation structure will affect the ventilation and heat dissipation of the transformer, thereby causing safety problems of electrical equipment. In addition, the active noise reduction technology of the substation electrical equipment based on the Huygens principle, in order to achieve the effect of eliminating noise in three-dimensional space, in actual engineering, too many secondary sound sources will be arranged, which will not only be limited by the application scene, but also make the noise reduction system more complex. SUMMARY

[0004] The present application relates to the field of power equipment noise control, and particularly relates to a sub-closed sound insulation structure substation active noise control system.

[0005] The technical scheme adopted by the present application is:

[0006] The substation active noise control system of a semi-closed sound insulation structure comprises a semi-closed sound insulation structure, sound-absorbing material, a reference microphone, an error microphone, a secondary sound source and an adaptive control system; the semi-closed sound insulation structure is arranged outside the substation, and an opening is arranged on one side wall of the semi-closed sound insulation structure; the sound-absorbing material is arranged on the inner wall surface of the wall corresponding to the opening side of the semi-closed sound insulation structure, and the sound-absorbing material is arranged in a gap with the corresponding inner wall surface; the sound-absorbing material adopts a single-layer parallel micro-perforated sheet of a sound-absorbing structure; the reference microphone is used to collect the primary noise signal of the transformer at the opening; the error microphone is used to collect the noise signal after cancellation; the secondary sound source is used to emit the cancellation sound signal under the control of the adaptive control system; the adaptive control system receives the primary noise signal and generates the noise cancellation signal for eliminating the noise by using the adaptive algorithm; and the output power of the secondary sound source is controlled after digital-to-analog conversion.

[0007] Further, the plate body of the parallel micro-perforated sheet is made of aluminum alloy, the perforation rate of the parallel micro-perforated sheet is 0.8%-1.2%, the thickness is 1 mm, and the hole diameter is 0.2 mm.

[0008] Further, the reference microphone, the error microphone, the secondary sound source and the adaptive control system constitute an adaptive active noise control device, and the active noise control device is arranged at the opening of the wall.

[0009] Further, the noise signal collected by the reference microphone and the error signal collected by the error microphone are respectively amplified by a preamplifier in a signal conditioning circuit, and after high-frequency filtering processing by the adaptive control system, the discrete digital signal is obtained as input by A / D sampling; the adaptive control system continuously adjusts the parameters by using the multi-channel least mean square filtering algorithm of the feedforward control structure according to the feedback error signal, so as to change the output cancellation signal of the secondary sound source; the output cancellation signal is converted by D / A after power amplification, and finally output by the secondary sound source, so as to be combined with the original noise signal; the adaptive control system continuously optimizes the effect of tracking the error signal, and the error is continuously reduced, so as to gradually achieve the best noise reduction effect to reduce the noise radiation to the external environment through the opening.

[0010] Further, the reference microphone is arranged at the edge of the opening corresponding to the incident side (i.e. one side of the inner wall surface of the wall), the error microphone is arranged at the midpoint position of each frame surface near the transmission side of the opening, the secondary sound source is arranged between the reference microphone and the error microphone, and the secondary sound source and the error microphone are one-to-one corresponding and arranged horizontally.

[0011] Further, the secondary sound source adopts a single-directional loudspeaker.

[0012] Further, the error microphone adopts a microphone.

[0013] Further, in the process "continuously adjusting parameters by using a multi-channel least mean square filtering algorithm to change the secondary sound source output cancellation signal", the adaptive control system specifically operates as follows:

[0014] Step 1, assuming that the multi-channel control system has one reference signal, m error microphones, and k secondary sound sources;

[0015] Step 2, at the n th moment, the system has k filtering channels, and the vector form of the entire system weight coefficient is:

[0016] W(n) = [W1(n), W2(n), …, W k (n)] Τ

[0017] Wherein each filtering channel weight vector has an order of L:

[0018] W j (n) = [w j1 (n), w j2 (n), …, w jL (n)] Τ

[0019] Step 3, at the n th moment, the input reference signal of the FIR filter has a vector form:

[0020] X(n) = [x(n), x(n-1), …, x(n-L+1)] Τ

[0021] Then the k secondary sound source output vector form Y(n) = [y1(n), y2(n), …, y k (n)] Τ , which satisfies:

[0022]

[0023] Step 4, the noise sound signal that propagates from the reference microphone to the m error microphones through the primary sound channel is calculated, and the corresponding expression is:

[0024] D(n) = [d1(n), d2(n), …, d m (n)] Τ

[0025] Step 5, the sound channel transfer function of the secondary noise signal emitted by the k secondary loudspeakers to the m error microphones is:

[0026]

[0027] where s mk (n) is the sound channel delay of the sound wave propagation from the kth secondary sound source to the mth error microphone;

[0028] Step 6, the noise residual signal group at the mth error microphone is calculated, and the specific expression is:

[0029] e(n) = D(n) + S(n)Y(n)

[0030] Step 7, the objective function J(n) based on the minimum total noise residual potential energy is constructed, and the expression is as follows:

[0031]

[0032] Step 8, the steepest descent method is used, and the gradient of the error signal square sum is set to make the unbiased estimation weight coefficient of J(n) have a minimum value:

[0033]

[0034] Step 9, r(n) is introduced as the filtered reference signal as the value of the input signal X(n) after being filtered by the secondary channel:

[0035] r ij (n) = s ij (n)x(n), i∈[1,m], j∈[1,k];

[0036] Step 10, the iterative formula of the entire system filter weight matrix is recursively obtained:

[0037] W(n+1) = W(n) - μ2e Τ (n)r(n),

[0038] Where μ is the iteration step size;

[0039] Step 11, the weight vector of each adaptive filter channel is decomposed as follows:

[0040]

[0041] The low-frequency micro-perforated plate sound absorption structure has low sound quality, high sound resistance, thin material, simple construction, good economic performance, wide sound absorption frequency band, solves the defects of high material consumption of the traditional sound absorption wall, great influence of dust and humidity after long-term use, and maintenance trouble, etc., and the opening active noise control device can not block the air inlet and air outlet of the main transformer room, solves the contradiction of effective ventilation and noise reduction, and further transfers the three-dimensional space noise reduction range to the opening local space noise reduction range, which can greatly save the material consumption of the secondary sound source and error microphone, and reduces the complexity of the active noise control system. BRIEF DESCRIPTION OF DRAWINGS

[0042] The application will be further described in detail below with reference to the drawings and specific embodiments.

[0043] Fig. 1 Semi-closed sound insulation structure diagram;

[0044] Fig. 2 Four-channel frame active noise control diagram for wall opening;

[0045] Fig. 3 Transformer active noise control system block diagram. EMBODIMENT

[0046] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application.

[0047] As shown in one of the drawings, Figs. 1 to 3 The application discloses a semi-closed sound insulation structure transformer substation active noise control system, which comprises a semi-closed sound insulation structure, sound absorption material, a reference microphone, an error microphone, a secondary sound source and an adaptive control system. An opening is arranged on one side wall of the semi-closed sound insulation structure. Sound absorption material is arranged on the inner wall of the wall corresponding to the opening of the semi-closed sound insulation structure, and the sound absorption material is arranged in a gap with the corresponding inner wall. The sound absorption material adopts a single-layer parallel micro-perforated thin plate. The reference microphone is used to collect the primary noise signal of the transformer at the opening, the error microphone is used to collect the noise signal after cancellation, the secondary sound source is used to emit the cancellation sound signal under the control of the adaptive control system, the adaptive control system receives the primary noise signal and generates the noise cancellation signal for eliminating the noise by using the adaptive algorithm, and the output power of the secondary sound source is controlled after digital-to-analog conversion. Further, as shown in Fig. 1The sound-absorbing material is arranged on the inner wall of the semi-enclosed sound insulation structure wall 1 of the transformer substation. The single-layer parallel micro-perforated sheet 3 is used. The sheet body of the single-layer parallel micro-perforated sheet 3 is made of aluminum alloy material. The perforation rate is 0.8%-1.2%. The thickness is 1 mm. The hole diameter is 0.2 mm. The cavity with a depth H of 200 mm is arranged on the wall surface with a reserved distance. It should be noted that, in order to facilitate the display, Fig. 1 In the wall, only one single-layer parallel micro-perforated sheet 3 is drawn. Actually, one or more single-layer parallel micro-perforated sheets 3 can be arranged on one side of the wall to form a sound-absorbing surface with an area smaller than that of the inner wall of the corresponding side of the wall.

[0048] Further, the adaptive active noise control device is composed of a reference microphone, an error microphone, a secondary sound source and an adaptive control system, as shown in Fig. 2 The active noise control device is arranged at the opening 2 of the wall 1. The reference microphone is arranged at the edge of the corresponding incident side of the opening 2 of the wall 1 (i.e. one side of the inner wall of the wall). The error microphone is arranged at the midpoint of each frame surface near the transmission side of the opening 2 of the wall 1. The secondary sound source is arranged between the reference microphone and the error microphone. The secondary sound source is a single-directional loudspeaker. The error microphone is a general microphone.

[0049] Further, in one embodiment, a transformer active noise control system is provided, as shown in Fig. 3 The noise signal collected by the reference microphone and the error signal collected by the error microphone are respectively amplified by the preamplifier in the signal conditioning circuit in the adaptive active noise control device. The error signal is processed by the high-frequency filter of the adaptive control system. The discrete digital signal obtained by A / D sampling is used as the input. The adaptive control system uses the multi-channel least mean square filter algorithm of the feedforward control structure to continuously adjust the parameters to change the output of the secondary sound source. The output signal is converted by D / A, amplified by the power amplifier and finally output by the secondary sound source. The output signal is combined with the original noise signal and continuously optimized to track the error signal. The error is continuously reduced. The system gradually achieves the best noise reduction effect to reduce the noise radiation to the external environment through the opening 2.

[0050] In one embodiment, in the process of "using a multi-channel least mean square filter algorithm to continuously adjust parameters to change the output of the secondary sound source", the specific operation process of the adaptive control system is as follows:

[0051] Suppose that the multi-channel control system has one reference signal, m error microphones and k secondary sound sources

[0052] Suppose that the reference signal input through the reference microphone is:

[0053] X(n) = [x(n), x(n-1),..., x(n-L+1)] Τ

[0054] At the n th moment, the system has k filtering channels, and the vector form of the entire system weight coefficient is:

[0055] W(n) = [W1(n), W2(n),..., W k (n)] Τ

[0056] Each filtering channel weight vector has an order of L:

[0057] W j (n) = [w j1 (n), w j2 (n),..., w jL (n)] Τ

[0058] At the n th moment, the vector form of the input reference signal of the FIR filter is:

[0059] X(n) = [x(n), x(n-1),..., x(n-L+1)] Τ

[0060] The output vector form of the k secondary sound sources is Y(n) = [y1(n), y2(n),..., y k (n)] Τ , which satisfies:

[0061]

[0062] When the noise propagates from the reference microphone to the m error microphones, it passes through the primary sound channel delay, and the sound signal becomes:

[0063] D(n) = [d1(n), d2(n),..., d m (n)] Τ

[0064] The sound channel transfer function of the secondary noise signal emitted by the k secondary loudspeakers to the m error microphones is:

[0065] s mk (n) is the sound channel delay of the sound wave propagation from the k th secondary sound source to the m th error microphone;

[0066] Then the noise residual signal group at the m error microphones is:

[0067] e(n) = D(n) + S(n)Y(n)

[0068] The system is based on the total noise residual sound potential energy minimum objective function J(n) as follows:

[0069]

[0070] By using the steepest descent method, set the gradient of the error signal square sum, so that the unbiased estimation of the weight coefficient of J(n) has a minimum value:

[0071]

[0072] Introducing r(n) as the filtered reference signal, which can be regarded as the value of the input signal X(n) filtered by the error channel:

[0073] r ij = s ij (n)x(n), i∈[1,m], j∈[1,k];

[0074] Recursive to obtain the entire system filter weight matrix iteration formula:

[0075] W(n+1)=W(n)-μ2e Τ (n)r(n)

[0076] Decomposition to obtain the weight vector of each adaptive filter channel as follows:

[0077]

[0078] Compared with the prior art, the present application has at least the following advantages:

[0079] The low-frequency micro-perforated panel sound absorption structure adopted by the present application not only has low sound quality and high sound resistance, but also has thin material, simple construction, good economic performance, wide sound absorption frequency band, solves the defects of high material consumption of traditional sound absorption wall surface, great influence of dust and humidity after long-term use, maintenance trouble and the like; at the same time, the opening 2 active noise control device can not block the main transformer room air inlet, air outlet and the like, solves the contradiction of difficult to have effective ventilation and noise reduction; in addition, the three-dimensional space noise reduction range is transferred to the opening 2 local space noise reduction range, which can greatly save the material consumption of secondary sound source and error microphone, and reduces the complexity of the active noise control system.

[0080] It is apparent that the described embodiments are only some — but not all — of the embodiments of the present application. The embodiments described in this application and features in the embodiments can be combined with each other in cases without conflict. The components of the embodiments of the present application, which are generally described and shown in the accompanying drawings, can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work, shall fall within the scope of protection of the present application.

Claims

1. An active noise control system for a substation with a semi-enclosed sound insulation structure, characterized in that: It includes a semi-enclosed sound insulation structure, sound-absorbing material, a reference microphone, an error microphone, a secondary sound source, and an adaptive control system. An opening is provided on one side of the semi-enclosed sound insulation structure. Sound-absorbing material is arranged on the inner wall of the wall corresponding to the opening, with gaps between the material and the corresponding inner wall surface. The sound-absorbing material is a single-layer parallel micro-perforated thin plate of the sound-absorbing structure. The reference microphone is used to collect the primary noise signal from the transformer at the opening, the error microphone is used to collect the canceled noise signal, and the secondary sound source is controlled by the adaptive control system to emit a canceled sound signal. The adaptive control system receives the primary noise signal and processes it using an adaptive algorithm to generate a noise-canceling signal for noise elimination. The output power of the secondary sound source is controlled after the mode conversion; the parallel micro-perforated thin plate is made of aluminum alloy, the perforation rate of the parallel micro-perforated thin plate is 0.8%-1.2%, the thickness is 1mm, and the hole diameter is 0.2mm; when the parallel micro-perforated thin plate is laid, a cavity is left at a set depth from the wall surface; the reference microphone, error microphone, secondary sound source and adaptive control system constitute an adaptive active noise control device, and the active noise control device is set at the wall opening; the reference microphone is set at the edge of the wall opening corresponding to the incident side, the error microphone is set at the midpoint of each frame surface of the wall opening near the transmission side, the secondary sound source corresponds one-to-one with the error microphone and is set at the same horizontal level, and the secondary sound source is set between the reference microphone and the error microphone.

2. The active noise control system for a substation with a semi-enclosed sound insulation structure according to claim 1, characterized in that: The noise signal collected by the reference microphone and the error signal collected by the error microphone are amplified by a preamplifier in a signal conditioning circuit, and after high-frequency filtering by the adaptive control system, they are sampled by A / D to obtain discrete digital signals as input. The adaptive control system continuously adjusts parameters based on the feedback error signal using a multi-channel minimum mean square filtering algorithm of a feedforward control structure to change the output cancellation signal of the secondary sound source. The output cancellation signal is converted by a D / A converter, then amplified by a power amplifier, and finally output by the secondary sound source to synthesize with the original noise signal. The adaptive control system continuously optimizes the tracking effect of the error signal, and the error is continuously reduced, gradually achieving the best noise reduction effect to reduce the noise radiated to the external environment through the opening.

3. The active noise control system for a substation with a semi-enclosed sound insulation structure according to claim 1, characterized in that: The secondary sound source uses a unidirectional loudspeaker.

4. The active noise control system for a substation with a semi-enclosed sound insulation structure according to claim 1, characterized in that: The error microphone uses a microphone.

5. The active noise control system for a substation with a semi-enclosed sound insulation structure according to claim 2, characterized in that: The specific operational flow of the adaptive control system in changing the secondary sound source output cancellation signal by continuously adjusting parameters using a multi-channel least mean square filtering algorithm is as follows: Step 1: Assume the multi-channel control system has 1 reference microphone, m error microphones, and k secondary sound sources. Step 2, at time n, the system has k filtering channels, and the vector form of the weight coefficients of the entire system is: W(n)=[W1(n),W2(n),…,W k (n)] T ; The weight vector for each filter channel has an order of L: W j (n)=[w j1 (n),w j2 (n),…,w jL (n)] T ; Step 3, at time n, the vector form of the reference signal input to the FIR filter: X(n)=[x(n),x(n-1),…,x(n-L+1)] T ; The calculated output vector form of the k secondary sound sources is Y(n)=[y1(n),y2(n)…,y k (n)] T It satisfies: Step 4: Calculate the delayed acoustic signal of the noise propagating from the reference microphone to the m error microphones through the primary acoustic channel. The corresponding expression is: D(n)=[d1(n),d2(n),…,d m (n)] T ; Step 5, the acoustic channel transfer function for the secondary noise signals emitted by the k secondary loudspeakers to the m error microphones is: Among them, s mk (n) represents the acoustic channel delay of the sound wave propagation from the k-th secondary sound source to the m-th error microphone; Step 6: Calculate the noise residual signal group at the m error microphones. The specific expression is as follows: e(n) = D(n) + S(n)Y(n); Step 7: Construct the objective function J(n) based on minimizing the total noise residual acoustic potential energy, as shown in the following expression: Step 8: Using the steepest descent method, the weight coefficients of the unbiased estimate that minimize J(n) are set as the gradient of the sum of squares of the error signals: Step 9: Introduce r(n) as the filtering reference signal and use it as the value of the input signal X(n) after filtering through the secondary channel: r ij (n)=s ij (n)x(n),i∈[1,m],j∈[1,k]; Step 10, recursively derive the iterative formula for the entire system filter weight matrix: W(n+1)=W(n)-μ2e T (n)r(n), In the formula, μ is the iteration step size; Step 11, the weight vector of each adaptive filter channel is obtained as follows:

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