I. User profile

Hengyang Valin Steel Pipe Co., Ltd. now has a cold rolling production line of ∮5, three hot rolling production lines of ∮89, ∮18 and ∮34, two tubing processing lines and two sets of round tube blanks for full horizontal continuous casting and arc continuous casting.

2. Power grid status and electrical equipment

1. Rolling mill transformers: ZS9-3/6.3 6.3KV/.75KV

2. The factory adopts nonlinear load equipment such as DC rolling mill, which produces a large number of harmonics when working, which has a great impact on the system and the nearby power grid, and at the same time causes a lot of losses, which not only affects the safety of power users, but also affects the safety of power users. This treatment is three main transformers in three continuous rolling in 89 branch factory.

3. Analysis of investment effect

1. Total investment: invest in 3 sets of TXL-1 low-voltage harmonic filtering devices, totaling 84, yuan;

2. Harmonic control and reactive power compensation effect

After the filter device was put into use, the harmonic voltage distortion rate dropped from 7.3% to 3.6%, and the harmonic current distortion rate also dropped from 26.% to 7%, and all harmonics were within the allowable values of the national standard. The power factor of the system has also increased from .8 to .96. After the filter device is put into use, the total reactive power consumed by the system has decreased by 252Kvar and the active power consumed by the system has decreased by 226KW, which is equivalent to saving about 1, kWh per month (kWh = power *16 hours *3 days).

3. Power-saving effect

(1) Power-saving after line frequency loss

Suppose that the maximum load of 6KV line in Henggang consumes 5 hours (τ) in a year, and the ratio of line power loss to transmission power is .8, which is expressed as δ. The annual electricity saving after compensation:

△ WL = SL * COSφ 1 * δ * τ * {1-[COSφ 1/COSφ 2] 2}

= .8× 9× .85× .8× 5× [1-(.8/.96).

Note: .85 is the load rate of main transformer

(2) The annual power saving of three transformers after compensation:

△ WT = 3×△ PD * (S1/S2) 2 * τ * [1-(COS φ 1/COS φ 2) 2]

= 34× {(.

where Pd is the total short-circuit loss of the transformer, which is 34KW

(3) The total annual power saving effect after compensation input:

△ W = △ WL+△ WT = 748+295728 = 143728 (kW h)

= 143728x .5 yuan = The working time of the load is 5 hours a year

(4) Saving of power rate electricity fee:

The annual power factor adjustment electricity fee that users should pay is about: (if the power factor assessment point of the local power supply bureau is .9, and the power factor of the user system before compensation is .84, the power factor penalty rate is +3%. )

power rate = active power rate * power rate

= active power * annual working hours * electricity rate * power rate = 612 * 5 * .5 * 3%

= 459, yuan

Since the reactive power compensation device is put into operation, the system power factor has reached more than .9 of the power factor assessment point, so no more power will be generated. That is to say, the electricity cost is saved by 459, yuan

(5) The total annual electricity cost is saved by 52.2+45.9 = 981, yuan

4. The payback period of investment is about 98.1/84=1.3 months

4. Conclusion

By investing in harmonic control equipment: < p At the same time, it reduces the impact of harmonics on the power grid, effectively controls harmonic pollution, and achieves great social benefits in the process of energy saving and emission reduction;

(2) As the invested equipment has a certain energy-saving effect, and the power factor is improved through reactive power compensation, the annual energy-saving benefit is obvious, and the investment can be recovered within 1.3 months.