Komprehensibong Analisis sa Teknolohiya sa Single-Phase Distribution Transformer sa Mga Diferenteng Sitwasyon sa Pag-aplikar

Ipakilala ang linya sa 10 kV ngadto sa sentro sa load. Pag-ila sa “gamay nga kapasidad, makapal nga puntos, mausab nga radius”, pagamit og bag-ong single - phase distribution mode, na nagpakita og notable nga pagbawas sa low - voltage line loss, taas nga kalidad sa power, ug reliability. Pagsusi sa ekonomiya ug reliability sa single - phase vs three - phase transformers sa uban uban nga scenario, kini nga paper analisa ang ilang applicable scope ug application suggestions.Ang mga single - phase transformers giklasipika batas sa distribution mode: o adunay neutral point sa 10 kV - side nga wala mapahimulos (medium - voltage side gigikanan sa distribution network’s line voltage U_AB/U_BC/U_AC, “phase - to - phase”), o adunay neutral line sa 10 kV - side nga mapahimulos (medium - voltage side gigikanan sa distribution network’s phase voltage U_AN/U_BN/U_CN, “phase - to - ground”), sama sa ipakita sa Figures 1 ug 2.

1 Pagsusi sa Loss sa Single - phase Distribution System

Sa single - phase distribution system, ang grid losses kasagaran gikan sa tulo ka bahin: losses sa single - phase transformers, losses sa high - voltage distribution lines, ug losses sa low - voltage distribution lines. Gigikanan sa D11 type, ang pagsusi ug analysis sa comprehensive line loss sama molonhi.

1.1 Single - phase Distribution Mode ug High - voltage Side Connection Voltage

Ang high - voltage side nagamit ang single - phase distribution mode ug gigikanan sa line voltages; ang low - voltage side nagamit ang single - phase three - wire system mode. Ang power loss sa distribution station area gi-compute isip:

Sa formula, R_L mao ang line resistance, R_dz mao ang equivalent resistance sa low - voltage line (unit: Ω); U mga 10 kV, T mao ang 8760 h (annual operating hours), ug U_pj mao ang 0.38 kV (average voltage sa low - voltage side). ΔP mao ang active energy nga recorded sa secondary metering (unit: kWh); ΔQ mga reactive energy nga recorded sa secondary metering (unit: kWh); K mga correction coefficient related sa load curve, may value nga 1.8.

1.2 Single - phase Distribution Mode (High - voltage Side Connected to Phase Voltage)

Ang high - voltage side nagamit ang single - phase distribution mode ug gigikanan sa phase voltages. Ang low - voltage side nagamit ang single - phase three - wire system. Ang power loss calculation formula sa distribution station area sama molonhi:

2 Application Comparison in Different Scenarios

Gigikanan sa usa ka rehiyon, gipili ang daghang typical application scenarios aron mogamit sa economics sa single - phase ug three - phase power distribution methods sa uban uban nga station areas. (Considering a 15 - year lifecycle and an electricity price of 0.6083 yuan/kWh)

2.1 Small Villages with Scattered Loads

Ang Village #1 adunay 37 residential users, kasagaran 33 single - phase users ug 4 three - phase users. Ang distribution transformer capacity mao ang 100 kVA, ang 10 kV line mao ang 838 meters long, ang low - voltage line mao ang 2170 meters long, ang maximum load mao ang 40 kW, ug ang annual loss hours mao ang 3400 hours.

• Three - phase power supply: Ang investment mao ang mahitungod 401,000 yuan, ug ang total economic loss over the lifecycle mao ang mahitungod 125,000 yuan.

• Hybrid single - phase/three - phase power supply: Ang investment mao ang mahitungod 512,000 yuan, ug ang total economic loss mao ang mahitungod 38,000 yuan.

Conclusion: Ang hybrid system's total investment mao ang mahitungod 24,000 yuan mas taas kaysa sa three - phase system.

2.2 Villages Unreachable by High - voltage Lines

Ang Village #2 adunay 75 residential users. Ang distribution transformer capacity mao ang 150 kVA, ang 10 kV line mao ang 752 meters long, ug ang low - voltage line mao ang 1583 meters long. Limited by the line corridor, ang 10 kV line wala maghatag ug power nearby, resulta mao ang maximum post - meter line length mao ang mahitungod 1008 meters ug ang minimum voltage mao ang 179 V sa line end. Ang maximum load mao ang 88 kW, ug ang annual loss hours mao ang 3400 hours.

• Three - phase power supply: Ang investment mao ang mahitungod 334,000 yuan, ug ang total economic loss over the lifecycle mao ang mahitungod 195,000 yuan.

• Single - phase power supply: Using 10 kVA and 20 kVA single - phase transformers, ang investment mao ang mahitungod 468,000 yuan, ug ang total economic loss mao ang mahitungod 27,000 yuan.

Conclusion: Ang single - phase system saves about 34,000 yuan in total investment compared to the three - phase system.

2.3 Large Villages with Concentrated Loads

Ang Village #3 adunay 210 residential users, kasagaran 209 single - phase users ug 1 three - phase user. Ang distribution transformer capacity mao ang 400 kVA, ang 10 kV line mao ang 855 meters long, ang low - voltage line mao ang 1968 meters long, ang maximum load mao ang 120 kW, ug ang annual loss hours mao ang 3400 hours.

• Three - phase power supply: Ang investment mao ang mahitungod 427,000 yuan, ug ang total economic loss over the lifecycle mao ang mahitungod 226,000 yuan.

• Hybrid single - phase/three - phase power supply: Replacing the original transformer with a 100 kVA three - phase transformer and using 10 kVA/20 kVA single - phase transformers for remote loads, ang investment mao ang mahitungod 710,000 yuan, ug ang total economic loss mao ang mahitungod 61,000 yuan.

Conclusion: Ang hybrid system's total investment mao ang mahitungod 118,000 yuan mas taas kaysa sa three - phase system.

2.4 Urban Street Load Areas

Market #4 adunay 171 users (all single - phase), kasagaran distributed along both sides of an urban street (residential and commercial mix). Ang distribution transformer capacity mao ang 500 kVA, ang 10 kV line mao ang 385 meters long, ang low - voltage line mao ang 748 meters long, ang maximum load mao ang 375 kW, ug ang annual loss hours mao ang 3400 hours.

• Three - phase power supply: Ang investment mao ang mahitungod 250,000 yuan, ug ang total economic loss over the lifecycle mao ang mahitungod 751,000 yuan.

• Single - phase power supply: Using 10 kVA and 20 kVA single - phase transformers, ang investment mao ang mahitungod 419,000 yuan, ug ang total economic loss mao ang mahitungod 291,000 yuan.

The single - phase system saves about 291,000 yuan in total investment compared to the three - phase system, and the application of power distribution methods in these typical scenarios is shown in Table 1.

3 Analysis of Single - phase Distribution Applicability

In urban areas with high load density, single - phase distribution is unsuitable for two reasons: 1) Higher investment costs due to the lack of transformer economies of scale; 2) Limited potential for loss reduction in short low - voltage lines.

Rural areas with three - phase power demands (e.g., farmland irrigation) require hybrid single/three - phase power supply systems. Opt for phase - to - phase single - phase connections to avoid costly 10 kV feeder renovation.

Economic Thresholds

• Transformer capacities: 50/100/150/200 kVA

• Line lengths: 1–3 km (in 0.5 - km increments)

• Max load: 50% of the transformer capacity

• Annual loss hours: 3,400

Quantitative analysis reveals that cost - effectiveness varies with line length and load. Hybrid systems help optimize investment and minimize losses.

4 Main Conclusions

In summary, the investment and losses of distribution transformers exhibit economies of scale. Large - scale use of single - phase power distribution is not the optimal approach. Its economic viability should be evaluated based on both the length of distribution lines and electricity consumption. Generally speaking, when the capacity of a three - phase distribution transformer in a station area reaches 150 kVA and the length of the low - voltage line exceeds 1.5 kilometers, converting the three - phase power distribution mode to the single - phase one is economically favorable.