1. Reasonable use of transformers should be based on the characteristics of the power consumption of the production enterprises to select a more flexible connection method, and can be adjusted in time with the load rate of each transformer to ensure that the transformer is operating at the optimal load state. The three-phase load of the transformer is balanced, and the unbalanced operation not only reduces the output but also increases the loss. To adopt energy-saving transformers, such as amorphous alloy transformers, the no-load loss is only 25% to 30% of the S9 series, which is very suitable for places with low annual utilization hours of transformers.
2. Pay attention to and reasonably carry out the transformer in the reactive power compensation operation, and the reactive power consumed is several times to several tens of times of the active power consumed. Reactive energy causes a large amount of active loss in the transmission in the power grid. In the general distribution network, the reactive power compensation capacity is installed in the low-voltage side 400V system of the transformer. It is generally considered that the load power factor compensation to 0.9-0.95 is already in place, and the reactive power compensation to the transformer is neglected, that is, l0kV Compensation on the high pressure side.
Reasonable selection of reactive power compensation mode, compensation point and compensation capacity can effectively stabilize the voltage level of the system and avoid a large amount of reactive power transmission through the line for long distance transmission and cause active power loss. The reactive power compensation of the capacitors in the distribution network usually adopts the combination of concentration, dispersion and local integration; the automatic switching mode of capacitors can be based on the height of the bus voltage, the direction of reactive power, the power factor, and the magnitude of the load current. The day and night time is divided. The specific choice should be determined according to the load power characteristics and the following problems should be noted:
(1) The proportion of single-phase load in high-rise buildings or residential gathering areas is large, and layered single-phase reactive power compensation or automatic phase-separated reactive power compensation should be considered to avoid other accidents caused by one-phase sampling signal for reactive power compensation. Two-phase over-compensation or under-compensation will increase the distribution network loss and will not achieve the purpose of compensation.
(2) After the parallel capacitor is installed, the harmonic impedance of the system changes, and the harmonics of a specific frequency will be amplified, which not only affects the life of the capacitor, but also makes the system harmonic interference more serious. Therefore, the location of the larger harmonic interference and the need to compensate for reactive power should be considered to increase the filtering device.
3. Renovation of low-voltage distribution lines, expansion of the current carrying level of the conductors According to the selection principle of the conductor cross-section, the minimum cross-section conductors that meet the requirements can be determined; but in the long run, it is not economical to select the minimum cross-section conductors. If the theoretical minimum section wire is increased by one to two, the cost of the line loss reduction can be recovered in a short period of time. Wire active power loss:
Px=3IjsR0L×10-6 (kW)
Where: Ijs—calculate current, A;
R0—wire resistance, 12/km;
L—wire length, m.
After the wire cross section increases, the line loss decreases:
ΔPx=3IjsΔR0L×10-6 (kW)
ΔWx=3IjsΔR0Lt×10-6(kWh)
Where: ΔPx - line loss active power loss reduction value, kW;
ΔWx—the line active power loss reduction value, kWh;
ΔR0—Line resistance reduction value, 12/km;
T—the number of hours the line is operating, h.
The electricity price per kWh is B yuan, and the price difference between two adjacent sections of cable per meter is E yuan. After the section is enlarged, the reduced line loss electricity fee M and the increased line investment N are:
M=ΔWx×B (yuan)
N=E×L (yuan)
If M=N, the electricity saving will be equal to the increase of investment, and you can get:
t=E/3IjsΔR0B×10-6(h)
Assume that the VV22-0.6/lkV four-core cable is laid underground, and the corresponding current carrying capacity when the current is 30 °C is calculated. The power saving effect after the cross section is increased is shown in the following table:
The above calculation only considers the active loss of the line, and does not consider the influence of the temperature rise and fall after the cross section is increased. After the cross section is increased, the line reactive loss will also decrease.
Since the service life of the wire is generally more than 10 years, the economic benefits created by increasing the energy saving and reduction of the section are very significant.
4. Reducing the number of contacts and reducing the contact resistance In the power distribution system, the connection between the conductors is ubiquitous, and the number of connection points is numerous, which not only becomes a safety weak link in the system, but also an important factor causing an increase in line loss. Attention must be paid to the construction process of the lap joint to ensure that the conductors are in tight contact, and a resistance reducing agent can be used to reduce the contact resistance. Pay special attention to the overlap between different materials.
5. Adopting energy-saving lighting appliances According to statistics, lighting power in industrialized countries accounts for more than 10% of total electricity consumption. With the continuous improvement of the living conditions of residents in China and the gradual improvement of lighting requirements in public places, the proportion of lighting electricity is increasing year by year. According to the layout of the building and the lighting place, the light source is arranged reasonably, the lighting mode is selected, and the light source type is an effective method for reducing energy loss. For example, the luminous flux of a 20W electronic energy-saving lamp is equivalent to the luminous flux of a 100W incandescent lamp. Promote high-efficiency energy-saving electric light source, replace the magnetic ballast with electronic ballast; electronic dimmer, delay switch, light control switch, voice control switch, inductive switch instead of seesaw switch used in public places, will greatly reduce lighting energy Consumption and line loss.
6. Adjust the power load, maintain the balanced power consumption, adjust the operation mode of the power equipment, distribute the load reasonably, reduce the power consumption during the peak hours of the power grid, increase the power consumption during the low valley period of the power grid, and reconstruct the unreasonable local distribution network to maintain the three. The phase balance makes the industrial and mining enterprises use electricity to balance and reduce the line loss.
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