Piece type transformation method of transformer tubular cooling system

[0010] Before the transformation, the original transformer used a radiator and air-cooled cooling method. There are currently 16 high-speed and noisy fans. The transformer no-load loss: 43.00kW, load loss: 154.09kW. The transformer adopts tubular radiator and is air-cooled. The relevant data of the tubular radiator are as follows: the installation center distance of the tubular radiator is 1 880 mm; the number of radiating pipes in each group: 120; the number of groups of the tubular radiator: 8 groups. 16 fans, model BF-4Q4, 250W, 1 450r/min. According to calculation, the effective heat dissipation area of ​​the air-cooled single-tube radiator is 31.00 square meters, and the total effective air-cooled heat dissipation area is: 31.00×8=248.0 square meters. There are 16 fan motors with a rated power of 0.25kW. The purpose of the transformation is to change the tube-type air-cooling to the chip-type natural cooling.

[0011] Analysis of the Causes of Unsatisfactory Heat Dissipation of Transformer

[0012] Whether the transformer self-cooling effect is ideal or not is due to the circulation of the transformer insulating oil, and the circulation of the transformer insulating oil is determined by the relative position of the heat dissipation center of the transformer and the heating center of the transformer. According to the comparison between theoretical calculation and actual operation of the on-site transformer, the ratio between the height of the heat dissipation center of the transformer and the height of the heating center is generally reasonable between 0.6 and 0.7. In this way, there is a certain height difference between the heating center and the heat dissipation center of the transformer, and the hot oil rises, which is beneficial to heat dissipation. See the original heat dissipation figure 1. The oil outlet of the pipe is 210mm away from the oil top surface of the body, which is easy to form a dead oil zone, which may cause local overheating of the oil surface.

[0013] The height of the heating center/the height of the cooling center = the height from the bottom plane of the transformer tank to the heating center/the height from the bottom plane of the transformer tank to the center of the radiator = (2 690/2-100) ÷ (1 880/2+600) = 1 245÷ 1 540 =0.808>(0.6~0.7).

[0014] Measures taken to meet cooling needs

[0015] In order to meet the requirements of transformer self-cooling and eliminate the dead oil area of ​​the transformer body, under the condition of ensuring the insulation distance of each charged body of the transformer, the transformer oil outlet must be re-opened, and the transformer oil outlet must be raised by 100mm according to the actual situation, while ensuring The distance between the fin radiator and the charged body. The fin-type radiator with a center distance of 1 600mm is selected, which raises the height of the heat dissipation center of the transformer, makes the ratio of the heating center and the heat dissipation center of the transformer reasonable, promotes the circulation of the transformer oil, and achieves the safety of the transformer when the fan motor is removed Operational requirements. See the situation after improvement figure 2.

[0016] Heating center height/heating center height = height from the bottom plane of the transformer tank to the heating center/height from the bottom plane of the transformer tank to the center of the radiator = (2 690/2-100) ÷ (1 600/2+380+600) = 1 245÷1 780=0.699 (between 0.6 and 0.7).

[0017] The technical parameters of the fin radiator used are as follows: the installation center distance is 1 600 mm, the slice width is 535 mm, and the number of groups: 16 groups.

[0018] The effective heat dissipation area of ​​the single-group self-cooling fin type radiator is calculated as: 22.77 m 2. The total effective cooling area of ​​natural cooling is: 22.77×16=364.32㎡.

[0019] Retrofit feasibility analysis

[0020] Comparison of heat dissipation area: The effective air-cooled heat dissipation area of ​​a single tube radiator is 31.00 square meters, and the total effective air-cooled heat dissipation area of ​​the tube radiator group is 248.00 square meters; the total effective self-cooling heat dissipation of 16 sets of fin radiators after the transformation The area is 364.32 square meters, which is 46.9% higher than before the transformation, and the cooling effect of the transformer can be guaranteed. After transformation: The height of the heating center/the height of the heat dissipation center=0.699. This data is relatively reasonable and has been greatly improved compared to the insulating oil circulation before the transformation.

[0021] Transformation effect

[0022] The power consumption is calculated as follows:

[0023] Before the renovation, there were 16 fan motors with a rated power of 0.25kW, which were running 24 hours a day. The fans were eliminated after the renovation. Therefore, the annual electricity consumption of the blowing device before and after the transformation is saved (0.25×16×24)×365=35 040kW·h, calculated at 0.5 yuan/kW·h, approximately 17,500 yuan will be saved;

[0024] Before and after the transformation, the annual electricity cost was about 17,500 yuan. According to the calculation that the main transformer can be operated for 15 years, the operation cost is saved by RMB 262,500. It can be seen that the economic benefits are very obvious only from the perspective of saving power consumption.

[0025] The comparison of overhaul and maintenance is as follows:

[0026] Before the transformation, a large number of motors and wind control loops need to be overhauled frequently;

[0027] After the transformation, the fin radiator basically has no maintenance work.

[0028] The noise comparison is as follows: ≤67dB before reconstruction, ≤55dB after reconstruction.

[0029] The transformer has been in operation for nearly a year after the transformation. By comparing the power consumption of the substation stations in the same period, it is basically consistent with the calculation results before the transformation, which greatly reduces the power loss; the temperature of the main transformer is lower than in the past under the same load of the main transformer 5℃~8℃, no defects occurred, which greatly reduces the operation and maintenance cost of the transformer and prolongs the service life of the transformer.