DYNA JOURNAL ENGINEERING

The United States of America has not yet decided on a project for a 500 KV with a length of just over 1,000 km and in China there are already transmission lines operating at 800 KV. As a comparison, the underwater HVDC line of the Peninsula with Mallorca, 250 KV to transmit 1,400 MW, the underground connection Spain-France in operation with about 65 km with cables for 320 KV and 2,000 MW and the future submarine connection Spain-France by the Bay of Biscay with about 260 km to transmit another 2,000 MW.

These types of connections are the ones that cause the least losses for transmissions of very high amounts of energy at great distances, which makes them capable of dealing with connections not only internal to a country but also of international exchange, making it possible to balance production-consumption between generation centres, for example, of renewable energies, very far away from areas of high consumption.

In this case, China is connecting the large wind production area of Xingkiang, the most northwestern and largest region in the country, with the province of Anhui, in the vicinity of Shanghai, which has a tenth of extension and a population of more than 60,000,000 inhabitants, three times more than the first. The power capable of transmitting the line will be 12,000 MW and the distance of the same 3,200 km.

The size and requirements for the equipment are unusual, as shown, for example, by the fact that insulation tests are carried out between 2.1 and 2.5 million volts, that a transformer-converter can weigh up to 800 T and that the elements under voltage are located on platforms that reach 14 to 16 m high for switches or 18 to 26 for capacitors.

The State Grid Corporation of China is carrying out this work, which began jointly with ABB and Siemens, who have been developing the technologies and designing the necessary conversion and control equipment, although some of it is already manufactured locally. The State Grid of China is possibly the largest organization in the world with one million employees and 1.1 billion customers. It also has interests in electricity distribution companies in countries such as Australia, Greece, Italy, the Philippines and Portugal and carries out projects for developing countries.

These possibilities open the door to large projects for the integration of electricity distribution, such as between China, Korea, Japan and Russia, to create a northwest Asian network that would include Mongolia. This would make it possible to make better use of generation, especially from renewable sources, which could be located in appropriate areas, even if they are far from the areas of consumption, with the consequent favourable impact on the environment.