A systematic method for controlling noise of urban distribution transformers

Abstract

The present invention relates to a systematic urban distribution transformer noise control method. It includes the determination of noise reduction targets, structural design of soundproof enclosures, material selection of soundproof enclosures, heat dissipation design of soundproof enclosures, noise reduction design of soundproof enclosures, and effect verification of soundproof enclosures. The noise control method provided by the present invention can be targeted at the structural characteristics, heat dissipation levels, and noise levels of different distribution transformers. By adjusting the structural form, material selection, heat dissipation, and noise reduction design parameters of the soundproof enclosures, while ensuring effective ventilation and heat dissipation of distribution transformers, the noise of different distribution transformers can be effectively suppressed, thereby ensuring a good acoustic environment around the distribution transformers.

Description

Technical Field

[0001] The invention belongs to the field of transformer noise control, and in particular relates to a systematic urban distribution transformer noise control method. Background Art

[0002] With the development of cities and the growth of population, the size of residential areas has continued to expand, and the power supply burden borne by the community distribution room has also increased. The distribution transformer is often in a high-load operation state. According to the provisions of GB12348-2008 "Environmental Noise Emission Standards for Industrial Enterprises at Factory Boundaries", residential areas belong to Class 1 acoustic environment functional areas, but the noise emitted by the distribution room often exceeds the limit requirements of such areas. In addition, the population is concentrated in the community, and the spatial distance between residents and noise sources is close, which makes them easily troubled by noise and causes residents' disgust.

[0003] There are currently two main ways to control the noise of distribution transformers. The first is to attach sound-absorbing panels to the inner wall of the distribution room, replace the inspection door of the distribution room with a soundproof door, and install a muffler at the exhaust vent of the distribution room, etc., to reduce the outward emission of noise from the distribution room and reduce the impact on the surrounding sound environment; the second is to replace the outer shell of the distribution transformer with a soundproof cover, and reduce the noise generated by the distribution transformer and reduce the impact on surrounding residents. Compared with the first method, the second method has the advantages of good noise reduction effect, less noise reduction material consumption, low carbon, and environmental protection. Therefore, it has become one of the main ways to control the noise of distribution transformers.

[0004] In order to effectively reduce the outward propagation of noise, the soundproof enclosure will inevitably reduce the opening, but the reduction of the opening area will affect the heat dissipation of the equipment. Therefore, noise reduction and heat dissipation have become one of the inevitable problems in the design of the soundproof enclosure, and noise reduction and heat dissipation belong to two different professional systems, which brings great challenges to the reasonable design of the soundproof enclosure. According to the on-site investigation, some distribution transformers did not achieve the expected noise reduction effect due to unreasonable selection of noise reduction materials and excessive opening area; although some distribution transformers have selected noise reduction measures, the opening area is too small, resulting in frequent overheating of the equipment, which brings inconvenience to the safe and stable operation of the equipment; in order to make up for the insufficient heat dissipation caused by the soundproof enclosure, some distribution transformers installed exhaust fans on the enclosure wall, but no reasonable silencer system was set up, resulting in the fan becoming a channel for the noise to propagate outward. Summary of the invention

[0005] The purpose of the present invention is to provide a systematic urban distribution transformer noise control method to address various deficiencies in existing designs. Through the use of this method, the contradiction between noise reduction and heat dissipation is resolved, providing a technical solution for the effective control of distribution transformer noise.

[0006] To achieve the above object, the technical solution of the present invention is: a systematic urban distribution transformer noise control method, comprising the following steps:

[0007] (1) Determination of noise reduction objectives;

[0008] (2) Structural design of the soundproof enclosure;

[0009] (3) Material selection of the soundproof enclosure;

[0010] (4) Heat dissipation design of the soundproof enclosure;

[0011] (5) Noise reduction design of the soundproof enclosure;

[0012] (6) Verification of the effectiveness of the soundproof enclosure.

[0013] In one embodiment of the present invention, the noise reduction target is determined in step (1), that is, the noise reduction amount of the target distribution transformer is set to the difference between the factory boundary noise sound pressure level and the factory boundary noise allowable sound pressure level.

[0014] In one embodiment of the present invention, the factory boundary noise sound pressure level is set as follows: if the target distribution transformer is an in-operation device, the factory boundary noise A-weighted sound pressure level is obtained by measurement, and then corrected by background noise to obtain the factory boundary noise sound pressure level; if the target distribution transformer is a device to be operated, the near-field noise A-weighted sound pressure level of the sound source equipment is obtained by querying the bidding technical specifications, which is the factory boundary noise sound pressure level; the allowable factory boundary noise sound pressure level should be obtained by querying the noise limit of the acoustic environment functional zone specified in GB12348-2008 "Environmental Noise Emission Standards for Factory Boundaries of Industrial Enterprises".

[0015] In one embodiment of the present invention, the structural design of the soundproof enclosure in step (2) should be based on the structural dimensions of the sound source equipment, the safety distance, and the maintenance space to obtain the structural dimensions of the soundproof enclosure; the shape of the soundproof enclosure should be similar to the outline of the distribution transformer and as close to the sound source housing as possible, while also considering the requirements of safety distance and convenient operation and maintenance.

[0016] In one embodiment of the present invention, the material selection of the soundproof cover in step (3) should be based on the noise level and noise spectrum of the distribution transformer, and suitable sound-absorbing materials and sound-insulating materials should be selected to ensure that the acoustic performance of the materials meets the noise reduction amount of the distribution transformer; the sound-absorbing materials can be selected from glass wool, polyester fiber wool, aluminum silicate fiber wool, pre-oxidized silk fiber wool, aluminum fiberboard, and micro-perforated board; the sound-insulating materials can be selected from steel plates and aluminum plates.

[0017] In one embodiment of the present invention, the heat dissipation design of the soundproof enclosure in step (4) should select a suitable heat dissipation fan and ventilation area of ​​the soundproof enclosure based on the heat dissipation level of the distribution transformer; the heat dissipation of the distribution transformer is the sum of the no-load loss and load loss of the equipment; the loss of the equipment can be queried based on GB / T6451-2015 "Technical Parameters and Requirements for Oil-Immersed Power Transformers" and GB / T10228-2015 "Technical Parameters and Requirements for Dry-Type Power Transformers".

[0018] In one embodiment of the present invention, the air volume of the heat dissipation fan should be calculated according to the following formula:

[0019] G>3600Q / ρ / c / (tp-tc)

[0020] Where:

[0021] G—Cooling fan air volume (m 3 / h);

[0022] Q—heat dissipation of distribution transformer (kW);

[0023] ρ—air density, generally 1.1466kg / m 3 ;

[0024] c—Specific heat capacity of air, generally 1.013 kJ / (kg·℃);

[0025] tp—exhaust air temperature (℃) (set temperature not greater than 45℃);

[0026] tc—air inlet temperature (℃) (maximum temperature not higher than 35℃).

[0027] In one embodiment of the present invention, the ventilation area of ​​the soundproof enclosure should be calculated according to the following formula:

[0028] S>G / v

[0029] Where:

[0030] S—Ventilation area of ​​the soundproof enclosure (m 2 );

[0031] G—Cooling fan air volume (m 3 / h);

[0032] v—wind speed at the vent, generally 10800m / h.

[0033] In one embodiment of the present invention, the noise reduction design of the soundproof enclosure in step (5) should be based on the noise level and noise spectrum of the distribution transformer, and a suitable muffler should be selected to ensure that the noise reduction of the muffler is not lower than that of the soundproof enclosure; the muffler can be selected with an appropriate muffler length and muffler sheet thickness.

[0034] In one embodiment of the present invention, the effect verification of the sound insulation cover in step (6) should be carried out using noise analysis and flow field analysis software to ensure that the expected goals of the distribution transformer are achieved; the noise analysis includes SoundPLAN and CadnaA acoustic simulation analysis software, and the flow field analysis software includes SFLUENT flow field simulation analysis software.

[0035] Compared with the prior art, the present invention has the following beneficial effects: the technical solution provided by the present invention can be targeted at the structural characteristics, heat dissipation levels and noise levels of different distribution transformers. By adjusting the structural form, material selection, heat dissipation, noise reduction and other design parameters of the sound insulation cover, while ensuring effective ventilation and heat dissipation of the distribution transformer, the noise of different distribution transformers can be effectively suppressed, providing strong support for designers' noise reduction design. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0038] like Figure 1 As shown, the present invention provides a systematic urban distribution transformer noise control method, comprising the following steps:

[0039] (1) Determination of noise reduction objectives;

[0040] (2) Structural design of the soundproof enclosure;

[0041] (3) Material selection of the soundproof enclosure;

[0042] (4) Heat dissipation design of the soundproof enclosure;

[0043] (5) Noise reduction design of the soundproof enclosure;

[0044] (6) Verification of the effectiveness of the soundproof enclosure.

[0045] The present invention is described in detail below with reference to examples.

[0046] Example 1

[0047] The voltage level of an oil-immersed distribution transformer in operation is 10kV, the capacity is 800kVA, the no-load loss is 1.12kW, the load loss is 8.89kW, the overall dimensions are 1470mm×1200mm×1450mm (length×width×height), and it is located in a Class 1 acoustic environment functional area. Noise reduction design is performed on the equipment.

[0048] (1) Determination of noise reduction targets

[0049] Through on-site noise measurement, it is known that the noise pressure level at the plant boundary of the station is 65dB(A) and the background noise is 40dB(A). According to the provisions of GB12348-2008 "Environmental Noise Emission Standards for Plant Boundaries of Industrial Enterprises", the noise at the plant boundary of the station does not need to be corrected, and the noise limit of the Class 1 acoustic environment functional zone is 45dB(A). The noise reduction of the distribution transformer is the difference between the sound pressure level of the plant boundary noise and the allowable sound pressure level of the plant boundary noise, that is, 65dB(A)-45dB(A)=20dB(A).

[0050] (2) Structural design of the soundproof enclosure

[0051] According to the dimensions of the distribution transformer, and taking into account the requirements of equipment safety distance and convenient operation and maintenance, the dimensions of the soundproof enclosure should be 2170mm×1900mm×2150mm (length×width×height).

[0052] (3) Material selection of sound insulation cover

[0053] According to the noise level and noise spectrum of the distribution transformer, the sound-absorbing material of the soundproof enclosure is selected from polyester fiber cotton with good low-frequency sound absorption performance, and the sound insulation material is selected from steel plate with good low-frequency sound insulation performance. The overall noise reduction effect of the soundproof enclosure should reach more than 20dB(A).

[0054] (4) Heat dissipation design of the soundproof enclosure

[0055] The heat dissipation of the distribution transformer is the sum of the no-load loss and load loss of the equipment, that is, 1.12kW+8.89kW=10.01kW. The air volume of the cooling fan can be calculated according to the formula G>3600Q / ρ / c / (tp-tc), that is, 3600×10.01 / 1.1466 / 1.013 / (10)=3102m 3 / h, the air volume of the cooling fan should not be less than 3102m 3 / h; the ventilation area of ​​the soundproof enclosure can be calculated according to the formula S>G / v, that is, 3102m 3 / h÷10800m / h=0.29m 2 The ventilation area of ​​the soundproof enclosure should not be less than 0.29m 2 .

[0056] (5) Noise reduction design of the soundproof enclosure

[0057] According to the noise level and noise spectrum of the distribution transformer, a silencer with a silencer length of 2000mm and a silencer sheet thickness of 100mm is selected to ensure that the silencer can achieve a noise reduction of more than 20dB(A) and the noise reduction effect is not lower than that of the soundproof cover.

[0058] (6) Verification of the effect of the soundproof enclosure

[0059] Using simulation analysis software such as SoundPLAN and FLUENT, the above-mentioned distribution transformer noise reduction design method was simulated and analyzed, and it was found that its noise reduction effect can achieve the expected goal.

[0060] Example 2

[0061] The voltage level of a certain operating dry-type distribution transformer is 10kV, the capacity is 1250kVA, the no-load loss is 2.6kW, the load loss is 11.8kW, the overall dimensions are 1950mm×1360mm×2200mm (length×width×height), and it is located in a Class 1 acoustic environment functional area. Noise reduction design is performed on the equipment.

[0062] (1) Determination of noise reduction targets

[0063] Through on-site noise measurement, it is known that the noise pressure level at the plant boundary of the station is 60dB(A) and the background noise is 45dB(A). According to the provisions of GB12348-2008 "Environmental Noise Emission Standards for Plant Boundaries of Industrial Enterprises", the noise at the plant boundary of the station does not need to be corrected, and the noise limit of the Class 1 acoustic environment functional zone is 45dB(A). The noise reduction of the distribution transformer is the difference between the sound pressure level of the plant boundary noise and the allowable sound pressure level of the plant boundary noise, that is, 60dB(A)-45dB(A)=15dB(A).

[0064] (2) Structural design of the soundproof enclosure

[0065] Since the dry-type distribution transformer is equipped with a protective casing, the outer dimensions of the soundproof enclosure can refer to the original casing dimensions, i.e. 1950mm×1360mm×2200mm (length×width×height).

[0066] (3) Material selection of sound insulation cover

[0067] According to the noise level and noise spectrum of the distribution transformer, the sound-absorbing material of the soundproof enclosure is selected from aluminum silicate fiber wool with good low-frequency sound absorption performance, and the sound insulation material is selected from steel plate with good low-frequency sound insulation performance. The overall noise reduction effect of the soundproof enclosure should reach more than 15dB(A).

[0068] (4) Heat dissipation design of the soundproof enclosure

[0069] The heat dissipation of the distribution transformer is the sum of the no-load loss and load loss of the equipment, that is, 2.6kW+11.8kW=14.4kW. The air volume of the cooling fan can be calculated according to the formula G>3600Q / ρ / c / (tp-tc), that is, 3600×14.4 / 1.1466 / 1.013 / (10)=4463m 3 / h, the air volume of the cooling fan should not be less than 4463m 3 / h; the ventilation area of ​​the soundproof enclosure can be calculated according to the formula S>G / v, that is, 4463m3 / h÷10800m / h=0.41m 2 The ventilation area of ​​the soundproof enclosure should be no less than 0.41m 2 .

[0070] (5) Noise reduction design of the soundproof enclosure

[0071] According to the noise level and noise spectrum of the distribution transformer, a silencer with a silencer length of 1500mm and a silencer sheet thickness of 100mm is selected to ensure that the silencer can achieve a noise reduction of more than 15dB(A) and the noise reduction effect is not lower than that of the soundproof cover.

[0072] (6) Verification of the effect of the soundproof enclosure

[0073] Using simulation analysis software such as SoundPLAN and FLUENT, the above-mentioned distribution transformer noise reduction design method was simulated and analyzed, and it was found that its noise reduction effect can achieve the expected goal.

[0074] Example 3

[0075] A three-phase double-winding non-excitation voltage-regulating oil-immersed distribution transformer to be operated has a voltage level of 10kV, a capacity of 800kVA, and an overall size of 1520mm×1200mm×1250mm (length×width×height). It is located in a Class 1 acoustic environment functional area, and a noise reduction design is performed on the equipment.

[0076] (1) Determination of noise reduction targets

[0077] By consulting the bidding technical specifications, we can find that the A-weighted sound pressure level of the near-field noise of the sound source equipment is no higher than 55dB(A). The noise pressure level of the plant boundary of this station is calculated as 55dB(A), and the background noise is 40dB(A). According to the provisions of GB12348-2008 "Environmental Noise Emission Standards for Plant Boundaries of Industrial Enterprises", the noise at the plant boundary of this station does not need to be corrected, and the noise limit of the Class 1 acoustic environment functional zone is 45dB(A). The noise reduction of the distribution transformer is the difference between the sound pressure level of the plant boundary noise and the allowable sound pressure level of the plant boundary noise, that is, 55dB(A)-45dB(A)=10dB(A).

[0078] (2) Structural design of the soundproof enclosure

[0079] According to the dimensions of the distribution transformer, and taking into account the requirements of equipment safety distance and convenient operation and maintenance, the dimensions of the soundproof enclosure should be at least 2220mm×1900mm×1950mm (length×width×height).

[0080] (3) Material selection of sound insulation cover

[0081] According to the noise level and noise spectrum of the distribution transformer, the sound absorbing material of the soundproof enclosure shall be pre-oxidized sound-absorbing felt with good low-frequency sound absorption performance, and the sound insulation material shall be aluminum plate with good low-frequency sound insulation performance. The overall noise reduction effect of the soundproof enclosure shall reach more than 10dB(A).

[0082] (4) Heat dissipation design of the soundproof enclosure

[0083] According to GB / T6451-2015 "Technical Parameters and Requirements for Oil-Immersed Power Transformers", the no-load loss of the distribution transformer is 0.98kW, the load loss is 7.5kW, and the heat dissipation is the sum of the no-load loss and the load loss, that is, 0.98kW+7.5kW=8.48kW. The air volume of the cooling fan can be calculated according to the formula G>3600Q / ρ / c / (tp-tc), that is, 3600×8.48 / 1.1466 / 1.013 / (10)=2628m 3 / h, the air volume of the cooling fan should not be less than 2628m 3 / h; the ventilation area of ​​the soundproof enclosure can be calculated according to the formula S>G / v, that is, 2628m 3 / h÷10800m / h=0.24m 2 The ventilation area of ​​the soundproof enclosure should not be less than 0.24m 2 .

[0084] (5) Noise reduction design of the soundproof enclosure

[0085] According to the noise level and noise spectrum of the distribution transformer, a silencer with a silencer length of 1000mm and a silencer sheet thickness of 100mm is selected to ensure that the silencer can achieve a noise reduction of more than 10dB(A) and the noise reduction effect is not lower than that of the soundproof cover.

[0086] (6) Verification of the effect of the soundproof enclosure

[0087] Using simulation analysis software such as SoundPLAN and FLUENT, the above-mentioned distribution transformer noise reduction design method was simulated and analyzed, and it was found that its noise reduction effect can achieve the expected goal.

[0088] Example 4

[0089] A load-changing dry-type distribution transformer to be transported has a voltage level of 10kV, a capacity of 1000kVA, and an overall size of 1420mm×1200mm×1180mm (length×width×height). It is located in a Class 1 acoustic environment functional area, and a noise reduction design is performed on the equipment.

[0090] (1) Determination of noise reduction targets

[0091] By consulting the bidding technical specifications, we can find that the A-weighted sound pressure level of the near-field noise of the sound source equipment is no higher than 55dB(A). The noise pressure level of the plant boundary of this station is calculated based on 55dB(A), and the background noise is 45dB(A). According to the provisions of GB12348-2008 "Environmental Noise Emission Standards for Plant Boundaries of Industrial Enterprises", the corrected noise of the plant boundary of this station is 54dB(A), and the noise limit of the Class 1 acoustic environment functional zone is 45dB(A). The noise reduction of the distribution transformer is the difference between the sound pressure level of the plant boundary noise and the allowable sound pressure level of the plant boundary noise, that is, 54dB(A)-45dB(A)=9dB(A).

[0092] (2) Structural design of the soundproof enclosure

[0093] Since the dry-type distribution transformer is equipped with a protective casing, the outer dimensions of the soundproof enclosure can refer to the original casing dimensions, i.e. 1950mm×1360mm×2200mm (length×width×height).

[0094] (3) Material selection of sound insulation cover

[0095] According to the noise level and noise spectrum of the distribution transformer, the sound absorbing material of the soundproof enclosure shall be aluminum fiber sound absorbing board with good low-frequency sound absorbing performance, and the sound insulation material shall be aluminum plate with good low-frequency sound insulation performance. The overall noise reduction effect of the soundproof enclosure shall reach above 9dB(A).

[0096] (4) Heat dissipation design of the soundproof enclosure

[0097] According to GB / T10228-2015 "Technical Parameters and Requirements for Dry-Type Power Transformers", the no-load loss of the distribution transformer is 1.71kW, the load loss is 8.02kW, and the heat dissipation is the sum of the no-load loss and the load loss, that is, 1.71kW+8.02kW=9.73kW. The air volume of the cooling fan can be calculated according to the formula G>3600Q / ρ / c / (tp-tc), that is, 3600×9.73 / 1.1466 / 1.013 / (10)=3015m 3 / h, the air volume of the cooling fan should not be less than 3015m 3 / h; the ventilation area of ​​the soundproof enclosure can be calculated according to the formula S>G / v, that is, 3015m 3 / h÷10800m / h=0.28m 2 The ventilation area of ​​the soundproof enclosure should not be less than 0.28m 2 .

[0098] (5) Noise reduction design of the soundproof enclosure

[0099] According to the noise level and noise spectrum of the distribution transformer, a silencer with a silencer length of 1000mm and a silencer sheet thickness of 100mm is selected to ensure that the silencer can achieve a noise reduction of more than 9dB(A) and the noise reduction effect is not lower than that of the soundproof cover.

[0100] (6) Verification of the effect of the soundproof enclosure

[0101] Using simulation analysis software such as SoundPLAN and FLUENT, the above-mentioned distribution transformer noise reduction design method was simulated and analyzed, and it was found that its noise reduction effect can achieve the expected goal.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Ordinary technicians in the relevant field can still modify or make equivalent substitutions to the specific implementation methods of the present invention with reference to the above embodiments. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A systematic urban distribution transformer noise control method, characterized in that: The steps include: (1) Determination of noise reduction objectives; (2) Structural design of the soundproof enclosure; (3) Material selection of the soundproof enclosure; (4) Heat dissipation design of the soundproof enclosure; (5) Noise reduction design of the soundproof enclosure; (6) Verification of the effect of the soundproof enclosure; In the step (4), the heat dissipation design of the soundproof enclosure is to select the ventilation area of ​​the heat dissipation fan and the soundproof enclosure according to the heat dissipation level of the distribution transformer; the heat dissipation of the distribution transformer is the sum of the no-load loss and the load loss of the equipment; The air volume of the cooling fan is calculated according to the following formula: G>3600Q / ρ / c / (tp-tc) Where: G—cooling fan air volume; Q—heat dissipation of distribution transformer; ρ—air density; c—specific heat capacity of air; tp—exhaust air temperature ℃, the set temperature is not greater than 45℃; tc—inlet air temperature ℃, the maximum temperature is not higher than 35℃; The ventilation area of ​​the soundproof enclosure is calculated according to the following formula: S>G / v Where: S—the ventilation area of ​​the soundproof enclosure; G—cooling fan air volume; v—wind speed at the vent.

2. A systematic urban distribution transformer noise control method according to claim 1, characterized in that: The step (1) determines the noise reduction target, i.e., sets the noise reduction amount of the target distribution transformer to the difference between the factory boundary noise sound pressure level and the factory boundary noise allowable sound pressure level.

3. A systematic urban distribution transformer noise control method according to claim 2, characterized in that: The factory boundary noise sound pressure level is set as follows: if the target distribution transformer is an operating device, the factory boundary noise A-weighted sound pressure level is obtained by measurement, and then corrected by background noise, which is the factory boundary noise sound pressure level; If the target distribution transformer is the equipment to be transported, the A-weighted sound pressure level of the near-field noise of the sound source equipment can be obtained by consulting the bidding technical specifications, which is the factory boundary noise sound pressure level; the allowable sound pressure level of the factory boundary noise should be obtained by consulting the noise limit of the acoustic environment functional zone specified in GB12348-2008 "Environmental Noise Emission Standards for Factory Boundaries of Industrial Enterprises".

4. A systematic urban distribution transformer noise control method according to claim 1, characterized in that: The structural design of the soundproof enclosure in step (2) should be based on the structural dimensions of the sound source equipment, the safety distance, and the maintenance space to obtain the structural dimensions of the soundproof enclosure. The shape of the soundproof enclosure should be similar to the outline of the distribution transformer and as close to the sound source housing as possible, while also considering the requirements of safety distance and convenient operation and maintenance.

5. A systematic urban distribution transformer noise control method according to claim 1, characterized in that: The material selection of the soundproof cover in step (3) should be based on the noise level and noise spectrum of the distribution transformer, and suitable sound-absorbing materials and sound-insulating materials should be selected to ensure that the acoustic performance of the materials meets the noise reduction amount of the distribution transformer; the sound-absorbing materials can be selected from glass wool, polyester fiber wool, aluminum silicate fiber wool, pre-oxidized silk fiber wool, aluminum fiberboard, and micro-perforated board; the sound-insulating materials can be selected from steel plates and aluminum plates.

6. A systematic urban distribution transformer noise control method according to claim 1, characterized in that: The noise reduction design of the soundproof enclosure in step (5) should be based on the noise level and noise spectrum of the distribution transformer, and a suitable muffler should be selected to ensure that the noise reduction of the muffler is not less than that of the soundproof enclosure; the muffler can be selected with an appropriate muffler length and muffler sheet thickness.

7. A systematic urban distribution transformer noise control method according to claim 1, characterized in that: The effect verification of the sound insulation cover in step (6) should be carried out using noise analysis and flow field analysis software to ensure that the expected goals of the distribution transformer are achieved; the noise analysis includes SoundPLAN and CadnaA acoustic simulation analysis software, and the flow field analysis software includes SFLUENT flow field simulation analysis software.

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