Under the sea crossing bridge connecting Beilun District and Meishan island free trade zone in Ningbo, Zhejiang Province, six "electric silver snakes" meander along the bridge towards Meishan island port area. In June this year, with the commissioning of the 110kV Qixing power transmission and transformation project, this cross sea power channel will send a continuous stream of power to the port area.

In 2008, the State Council approved the establishment of Ningbo Meishan bonded port area, which is the fifth bonded port area in China after Shanghai Yangshan, Tianjin Dongjiang, Dalian Dayaowan and Hainan Yangpu. In the same year, Ningbo Municipal Party committee and municipal government made a decision on speeding up the construction of Meishan island.

In September 2009, various construction projects, known as "Meishan" speed, were fully opened on the island. More than 400 mu of storage land began piling, and more than 10 infrastructure projects were started. The power supply of the island's only 35kV Meishan substation was in short supply, so the power construction was urgent. To this end, Ningbo Electric Power Bureau adheres to the principle of special affairs and special handling, and carries out a special power construction scheme tailored for Meishan island and meeting the long-term development needs of the port area.

Tailor made island "power accelerator"

Special power construction means that every link from feasibility study, design to construction will closely focus on the construction and development needs of the port area, which means more comprehensive, more detailed and more intimate construction and service. At the beginning of 2013, after nearly five years of efforts, the 110kV Qixing power transmission and transformation project has entered the critical stage of construction. In the face of such a high-speed development of the island, the protection of the environment and resource conservation has become the work of Ningbo Electric Power Bureau.

"In view of the long-term development environment of Meishan island port area, the overhead lines in this area are undergoing" up to down "transformation Project design director said. From the perspective of the long-term development of the port area, the conventional overhead line is bound to have an impact on the landscape of the gateway of Meishan bridge and the future development and construction of the area where the line passes through.

Therefore, Ningbo Electric Power Bureau plans ahead of time, on the one hand, the overhead lines in the development area will be transformed into the ground; on the other hand, 110 kV cables with a cross-section of 1000 square mm will be used for extremely difficult cross sea laying, so as to improve the "regional quality" of Meishan island with technical quality.

"In order to match the development of the island and the load characteristics of the port area, the voltage level of the distribution network in the port area is selected as 20 kV." The project design director said that at present, the Qixing power transmission and transformation substation project on Meishan island is under construction.

Previously, in order to save island resources and achieve the best power supply quality, Ningbo Electric Power Bureau mobilized technical force, expanded the scope of investigation, strengthened the investigation, fully combined with Meishan island's "long east-west, narrow north-south" characteristics, proposed to build a 20 kV smart distribution grid on Meishan Island, reducing the number of 110 kV substations in the island from 3 to 2, thus saving lines to the maximum extent Channel resources and land resources.

Laying "energy artery" across the sea

In April, the transmission line project from 220kV Xianxiang gan'ao line to 110kV Qixing substation entered the most critical stage of cross sea cable laying. This short 1.1km carries three firsts of 110kV cable in Ningbo: the first time laying cable with a section of 1000mm2; the first time carrying out cable construction along with the cross sea bridge; and the first time setting cable expansion joint device according to the bridge expansion joint. From the very beginning, engineering construction is faced with various difficulties and challenges.

There are fast lanes on both sides of Meishan Island Bridge, and the cable laying space in the middle of the bridge is very narrow. Each cable expansion device weighing 5 tons is faced with the dilemma of being unable to be in place after it is transported to the construction site. "Brothers, first dismantle, transport to the bottom and then assemble." Ye Zhen, the leader of the cable team, immediately disassembled one cable telescopic device into easy lifting and moving parts with more than 20 hands.

Crane, shoulder, a few times down, in this still has a trace of cool season, everyone has been sweating. After the parts were transported to the designated location, in order not to affect the subsequent construction, the construction team members simply "cat" for five days in a narrow space, like building blocks, carefully assembled all the five expansion devices.

After solving the equipment problems, new difficulties are coming one after another. On April 12, in the hunting sea breeze of Meishan Island Bridge, the cable straightener had just stopped. Ye Yan and several construction workers once again discussed the construction scheme. According to the previous work experience, we can use the difference of the relative position between the cable straighteners to realize the bending of the cable. But after the field trial, it is found that the straightening machine is heavy and slow, and can only construct 100 meters per day. There are 6000 meters of cable to be laid on the bridge, and it will take 60 days to complete. But the whole project must be put into operation in June. What should we do?

"We must find a way to complete this cable laying in the shortest possible time." In the fierce sea breeze, everyone heard Ye Yan's firm voice. After more than ten hours, six solutions and dozens of tests, the construction scheme of using the chain block as the cable straightening tool was finally approved.

"One, two, three, up!" 10 pairs of green tendons of the hand along the cable diameter direction to tighten the chain block, while trying to pry 9 tons of cable. Six silver "giant snakes" gradually emerged, and simple and efficient construction also reduced the construction period to 10 days.

"In just a few years, Meishan island has become a new" giant ship "in the southeast coast from a barren and barren land. The key is to rely on strong power support." Beilun sub district.