Technical and Economic Advantages of UHV DC Transmission

Compared with ultra-high voltage DC at the ±600 kV level and below, the main technical and economic advantages of UHV DC transmission can be summarized in the following six aspects:

1. Large conveying capacity. Using 4000 ampere thyristor valves, the ±800 kV DC UHV transmission capacity can reach 6.4 million kilowatts, which is 2.1 times that of the ±500 kV, 3 million kilowatt high-voltage DC method, and is the ±600 kV, 3.8 million kilowatt high-voltage DC method. 1.7 times of that, which can give full play to the advantages of large-scale power transmission.

2. The power transmission distance is long. The use of ±800 kV DC transmission technology makes ultra-long-distance power transmission possible, and the economic transmission distance can reach 2,500 kilometers or even further, providing transmission guarantee for the development of large hydropower bases in southwest China.

3. Low line loss. When the total conductor cross-section and transmission capacity are the same, the resistance loss of a ±800 kV DC line is 39% of a ±500 kV DC line and 60% of a ±600 kV DC line. This improves transmission efficiency and saves money. Running costs.

4. Project investment province. According to calculations by the relevant design department, for ultra-long distance and ultra-large capacity transmission needs, the comprehensive cost per unit transmission capacity of the ±800 kV DC transmission solution is approximately 72% of that of the ±500 kV DC transmission solution, which saves significant project investment benefits.

5. The corridor utilization rate is high. The line corridor of the ±800 kV, 6.4 million kilowatt DC power transmission plan is 76 meters, and the transmission capacity per unit corridor width is 84,000 kilowatts/meter. It is a ±500 kV, 3 million kilowatt plan and a ±620 kV, 3.8 million kilowatt plan. It is about 1.3 times that of power transmission corridors, improving the utilization efficiency of transmission corridors and saving valuable land resources; due to the large transmission capacity of single-circuit lines, it significantly saves limited resources at valleys and river crossing points.

6. Flexible operation mode. The State Grid Corporation of China's UHV DC transmission plans to adopt a 400+400 kV double-twelve pulsation converter series connection scheme, which has a flexible operation mode and greatly improves system reliability. If any converter valve module fails, the system can still guarantee the delivery of 75% of the rated power.

HZC-4080 High Voltage Switch Characteristics Tester