The long red dragon in front of us is the Yuanjiang Bridge on the China-Laos Railway. The 51.2-meter-high electrical tower is extremely small in the grand view, and the hundreds of-meter-long cross-river transmission line is almost invisible.

220kV Yuannan Qianxian Tower No. 029

But the railway is inseparable from electricity. Soon, electric trains will sprint across this bridge, going north to Kunming and Yuxi, or south to Pu'er and Xishuangbanna, until they reach Vientiane, Laos.

The China-Laos Railway connects Kunming, China and Vientiane, Laos. The total length of the railway is more than 1,000 kilometers. It is a national first-class electrified railway. The China-Laos Railway is a docking project between China's Belt and Road Initiative and Laos' strategy of "turning a land-locked country into a land-union country". After opening to traffic, the travel time by bus from Kunming to Xishuangbanna will only take about 3 hours, and it is expected that it will arrive at Vientiane, the capital of Laos.

Construction site of external power supply project in Laos section of China-Laos railway

In Laos, the external power supply project of the Laos section of the China-Laos Railway is invested by the Lao China Power Investment Company, a joint venture between China Southern Power Grid Yunnan International Company and the Lao State Power Company, which is responsible for investment, construction and operation and maintenance. It was completed as scheduled on March 31, 2021.

In China, the external power supply project for the domestic section of the China-Laos Railway was invested and constructed by China Southern Power Grid Yunnan Power Grid Company. Along the way, it passes through the three prefectures of Yuxi, Pu'er and Xishuangbanna. The project will build 3 new 220kV switch stations, 1,587 poles and towers, and a line of 679.8 kilometers. The power supply project provides dual-circuit power supply for 14 traction transformers along the China-Laos Railway. “One main and one standby, each as a backup” ensures the safe and stable operation of the China-Laos railway. Today, the construction of the power supply project is nearing completion. Along the silver line of the iron tower, we will take you to understand those things in the China-Laos railway.

Days

Yuanjiang is located in the hot and dry valley region of Yunnan Province, with a hot climate. From April to June, there are often high temperatures above 40 degrees. In this kind of weather, if you touch the tower directly without wearing gloves, blisters can be burnt out.

Tower construction site

"In order to ensure the progress of the project and also for the safety of the personnel, the construction personnel from the tower to the tower, a single operation time is 1 hour, not more than 1.5 hours." China Southern Power Grid Yunnan Yuxi Power Supply Bureau Planning and Construction Management Center Pan Zenghui said: " Everyone needs to bring two 1.5-liter bottles of mineral water to the tower. When they come down, they drank them all.” In fact, shortly after the construction of the project started in December 2019, it was affected by the new crown pneumonia epidemic and other months, and several months of construction period were lost. I missed the time when the weather was most comfortable at the beginning of the year, and I was faced with the high temperature and the rainy season that lasted for half a year. These have brought great troubles to the construction of the project, and it is inconvenient to get up and running without talking about stoppages from time to time.

As we all know, Yunnan has high mountains and many trees, and the mountain roads are rugged and difficult to walk in areas crossed by some routes. Fang Zhidong, the project manager of Section 6 of the project and China Southern Power Grid Yunnan Power Transmission and Transformation Company, said: "It is already very good to be able to push the car forward with an excavator."

The project needs to carry a large amount of sand, cement, metal tower materials and other materials. At the construction site of the 6th bid section, Fang Zhidong and the others used this kind of crawler crawler. About 2 tons of tower materials can be transported at a time, but a single-way mountain road with more than 4 kilometers can only work 12 hours a day, and it can only go back and forth twice.

Transporting tower materials by caravan

In many places where there are no roads, there are no machinery and vehicles to rely on, and they can only be carried by mules, horses and humans. In the Nanxi River Traction Transformation Project in Yuxi Section, because mules and horses are difficult to move, the materials of 2 base towers were carried by the construction team to the construction site on foot for more than 100 meters. Only the tower materials are heavy. About 72.92 tons.

Geographical advantage

The construction of the external power supply project for the domestic section of the China-Laos Railway is not only the persistence of physical strength and perseverance, but also tests the wisdom and vision of power grid builders.

Guineng Switch Station

It can be seen that on the right are various switchgear devices, and what does the large open space on the left do? This is a place reserved for substation equipment. At the beginning of the planning, the power grid people realized that the construction of the external power supply project of the domestic section of the China-Laos railway should not only meet the needs of railway power supply, but also be integrated into the overall consideration of building the power grid and serving the local economy and people's livelihood. Therefore, “our line and switchyard construction are all about embedding it into Pu'er power grid construction for the next ten years.” said Chen Ke, Planning and Construction Management Center of Yunnan Pu'er Power Supply Bureau of China Southern Power Grid: “Now this is the Guineng switchyard. But the second phase of construction is about to begin. In the future, this will be the 220kV Guineng Substation."

It is the consensus of the three power grids of Yuxi, Pu'er and Xishuangbanna to integrate the construction of the external power supply project of the railway into the construction of the large power grid.

The power supply line crosses roads and railways and is connected to the Nanxihe Traction Substation

The railway is a first-class load, which has extremely high requirements for power supply reliability. Engineer He Wei of Yuxi Power Supply Bureau introduced that during the construction process, the dual power supply method was adopted. The 220kV Yuanjiang substation was connected once to the Nanxihe traction substation, and the 220kV Guineng switch station was also connected once again. To the Nanxihe traction substation, realize dual power supply. On this basis, a new line of Yuanjiang Substation-Guineng Switching Station with dual separate conductors was added to another line to realize the hand-in-hand loop network from Yuxi to Pu'er, making the operation of the power grid more stable and reliable.

People and

Exhausting energy and racking their brains are only to promote the construction of the external power supply project for the domestic section of the China-Laos railway. But if you want to ask what is the hardest? The most common answer from builders is "coordination." The power supply project is related to the China-Laos railway and is the infrastructure construction to protect the public interest. However, the construction of the project involves multiple interests such as railways, forestry, government, and the public. Planning and balancing various relationships with a forward-looking perspective have become essential qualities for power grid builders.

Judging from the map, the initial location of Gasaqi is within easy reach of the railway station and airport.

On June 19, arrived at Xishuangbanna Station of China-Laos Railway. Standing on the construction site, one can clearly see the planes taking off and landing at Gasa Airport next to it. Zhao Tibin, deputy director of the Yunnan Xishuangbanna Power Supply Bureau of China Southern Power Grid, pointed to a big pothole and said: This is the original address of the railway gasa traction substation.

The Mohan traction substation is backed by the railway. One hundred meters on the left is the Mohan Station of the China-Laos Railway

The railway traction transformer is a substation that functions as a "transit station". The 220kV AC power of the grid is converted into 27500V through this, and then the catenary is introduced to supply power for the train. It is a natural and excellent choice for the railway to build a traction change site next to the railway station, but choosing a location near the airport can make the power supply bureau difficult. If the location of the traction transformer is selected here, some of the lines built by the power grid will inevitably pass through the aviation height restriction zone, which means that in addition to the normal procedures, aviation audits are required, which will cause project delays and increase later costs.

Nanlianshan tunnel well. The power grid lines are connected to the traction station from above the tunnel; the traction station goes down from here to connect to the railway power supply network

Zhao Tibin understands that if the Xishuangbanna Power Supply Bureau finds it inappropriate, it must propose a better alternative. Open the map and take a closer look at the site of the original towing station. The airport is to the west and the Lancang River to the north. To avoid the prosperous city to the east, you can only look south. After many on-site visits, an open space was found outside the inclined shaft of the Nanlianshan Tunnel constructed by the railway, which meets the technical requirements of railway power supply. But it also means that the railway department will move the traction station 10 kilometers south and increase the investment of millions.

The rest of the time is to continue to persuade the railway with the plan. Zhao Tibin found relevant personnel no less than 10 times. After much discussion and coordination, the railway side accepted the change proposal put forward by the Xishuangbanna Power Supply Bureau. "The relevant person in charge of the Xishuangbanna Power Supply Bureau took the initiative to connect with us early, and communicated, coordinated and confirmed with the aviation evaluation unit, the Civil Aviation Administration, and Gasa Airport many times during the feasibility study, preliminary establishment, and installation stages to ensure the smooth passage of the aviation evaluation. "Said Lei Kai, an engineer at the Southern Dian Headquarters of Kunming Railway Administration Group Company.

Gasaqian under construction

Now, the construction of the traction transformer near the inclined shaft of the tunnel is about to be completed, and external power supply projects such as overhead lines and iron towers are ready to be put in place and are on standby at any time.

"This is not a question of right or wrong between several parties. The engineering construction must consider safety, reliability, economy, and feasibility." Zhao Tibin said: "If the work is not done well in the early stage, it will be very troublesome in the later stage. Perhaps it is reported from your news. The angle sounds not enough to overcome difficulties, but the best project is like this. It seems ordinary and strange, and it is as easy but difficult." Editor/He Yuting