What are the technical measures for loss reduction and energy saving in distribution systems?

1.Reasonable Use of Transformers
Transformers should be selected with flexible winding configurations according to the power consumption characteristics of industrial enterprises, and load adjustments should be made promptly based on each transformer’s load rate to ensure operation at optimal loading conditions. Three-phase loads on transformers should be kept as balanced as possible; unbalanced operation not only reduces output capacity but also increases losses. Energy-efficient transformers should be adopted—for example, amorphous alloy transformers have no-load losses that are only 25%–30% of those of S9-series transformers, making them especially suitable for applications with low annual utilization hours.

2.Emphasis on and Rational Implementation of Reactive Power Compensation
During operation, a transformer consumes reactive power that is several to dozens of times its active power consumption. The transmission of reactive energy through the grid causes substantial active power losses. In typical distribution networks, reactive compensation devices are installed on the low-voltage side (400 V system) of transformers. It is commonly believed that compensating the load power factor to 0.9–0.95 is sufficient, while the reactive power compensation for the transformer itself—i.e., compensation on the 10 kV high-voltage side—is often overlooked.

Reasonably selecting the method, location, and capacity of reactive power compensation can effectively stabilize system voltage levels and avoid transmitting large amounts of reactive power over long distances, thereby reducing active network losses. For distribution networks, reactive compensation is usually implemented through a combination of centralized, decentralized, and local approaches. Automatic switching methods may be based on bus voltage levels, direction of reactive power flow, power factor magnitude, load current size, or time-of-day scheduling. The specific selection must be determined according to load characteristics, with attention to the following issues:

(1) In high-rise buildings or residential clusters where single-phase loads account for a large proportion, layered single-phase reactive compensation or automatic phase-by-phase reactive compensation should be considered. Relying on sampling from only one phase for reactive compensation may cause over-compensation or under-compensation in the other two phases, increasing distribution network losses and defeating the purpose of compensation.

(2) After installing shunt capacitors, the system’s harmonic impedance changes, potentially amplifying harmonics at certain frequencies. This not only affects capacitor lifespan but also exacerbates harmonic interference in the system. Therefore, at locations with significant harmonic distortion that still require reactive compensation, harmonic filter installations should be considered.

3. Upgrading Low-Voltage Distribution Lines and Increasing Conductor Ampacity
According to standard conductor sizing principles, the minimum conductor cross-section that meets requirements can be determined. However, from a long-term perspective, using the minimum-size conductor is not economical. Increasing the conductor size by one or two standard steps allows the savings from reduced line losses to recover the additional investment in a relatively short period.

4. Reducing the Number of Connection Points and Lowering Contact Resistance
Connections between conductors are widespread in distribution systems, and the large number of connection points not only creates safety vulnerabilities but also significantly contributes to increased line losses. Construction practices at joints must be strictly controlled to ensure tight contact, and contact resistance can be further reduced by using conductive joint compounds. Special attention must be paid to connections between dissimilar materials.

5. Adopting Energy-Efficient Lighting Equipment
Statistics show that in industrially developed countries, lighting accounts for more than 10% of total electricity consumption. As living conditions in China continue to improve and lighting requirements in public spaces rise, the proportion of lighting electricity consumption is steadily increasing. Reasonably arranging light sources according to building layout and lighting needs, selecting appropriate lighting methods, and choosing efficient lamp types are effective ways to reduce losses and save energy. For example, a single 20 W energy-saving lamp provides the same luminous flux as a 100 W incandescent lamp. Promoting high-efficiency electric light sources, replacing magnetic ballasts with electronic ballasts, and using electronic dimmers, time-delay switches, photoelectric switches, acoustic switches, and motion-sensor switches instead of toggle switches in public areas will significantly reduce lighting energy consumption and line losses.

6. Load Shifting and Balanced Electricity Usage
Adjust the operating modes of electrical equipment, allocate loads rationally, reduce peak-hour grid demand, and increase off-peak usage. Upgrade inefficient local distribution networks to maintain three-phase balance, ensuring balanced electricity consumption in industrial and mining enterprises and thereby reducing line losses.