The power grid extensively uses high-voltage cross-linked cables, and it is necessary to support the use of domestically produced high-voltage cable insulation materials. This is the future development direction of high-voltage cable materials, "said Yang Liming, the chief expert of cables at the State Grid Electric Power Research Institute. Only by breaking through technological difficulties, developing new materials, truly realizing the localization of high-voltage cable insulation materials, and meeting the demand of the high-voltage cable market, can we promote the comprehensive quality development of the high-voltage cable industry.

The process of localization is in full swing

It is understood that China began producing medium voltage cross-linked polyethylene insulated power cables in the 1970s, with both insulation and shielding materials imported. Domestic cable materials have always been very backward. Before 1986, high-voltage cross-linked cables were rarely used in domestic power grids.

The development of cables is the development of new materials, and the system of cables is also the material system. Cable materials mainly include insulation materials, semiconductor materials, and conductor materials. In the process of cable manufacturing, there is no research and development foundation for insulation materials, which leads to serious lagging of insulation materials and cannot meet the needs of cable manufacturing and cable engineering.

In the mid-1990s, Chinese state-owned enterprises began trial production of high-voltage cross-linked cables, with imported insulation and shielding materials. However, problems still occurred during the experimental process after the trial production of insulation materials.

Entering this century, State Grid Corporation of China (SGCC) requires all domestic cables to be used for high-voltage cable procurement through bidding. All 220 kV cable systems in ultra-high voltage are purchased domestically. In recent years, domestic cables have also been adopted in the 500 kV cable projects in Beijing and Shanghai. All domestically produced cables are particularly suitable for ultra-high voltage flexible DC cable engineering, which has brought great driving force to the development of new products for Chinese cable enterprises. However, some insulation materials for high-voltage cables still need to be imported.

To break the problem of importing insulation materials for high-voltage cables and truly achieve high-end product structure, it is essential to improve the technological content and new technology research and development level of cable manufacturing. In recent years, some high-quality cable companies have started the path of localization through independent technological innovation. Zhejiang Wanma Polymer Materials Co., Ltd. (referred to as "Wanma Polymer") has produced high-voltage cable insulation materials, making a breakthrough contribution to the localization of insulation materials.

The localization of high-voltage cable insulation materials independently developed by Wanma Polymer has broken the monopoly of foreign manufacturers, and will naturally form direct competition with foreign manufacturers in product prices and various services. This not only strongly supports the rapid and healthy development of the high-voltage cable industry, but also further promotes independent innovation of enterprises.

We still need to break through technical bottlenecks

High voltage direct current transmission, due to its unique advantages in long-distance and high-capacity power transmission and grid interconnection, is the main trend of future power grid development, suitable for supplying power to islands, increasing the capacity of urban load centers, and connecting wind power to the grid. The relevant plan clearly states that in the next decade, 18 key areas for the development of polymer materials will be included in the development plan. The country has continuously increased its emphasis on the manufacturing and research of insulation materials, further ensuring the technological development of high-voltage cable insulation materials and laying the foundation for the research and development of high-voltage cables for high-voltage direct current transmission.

At present, China's high-voltage DC transmission mainly uses oil-paper insulated high-voltage DC power cables and DC plastic cables. However, the manufacturing process of oil-paper insulated cables is complex and the cost of operation and maintenance is high. One of the main factors restricting the development of flexible DC transmission projects in China has always been the complete monopoly of cable materials for DC cables by foreign companies. Experts say that the key technical bottlenecks of DC cable materials mainly involve two aspects: the preparation of ultra-clean polyethylene raw materials and the nano modification technology of cross-linked polyethylene.

In order to break through this bottleneck, in 2009, Yangzi Petrochemical BASF and Wanma Polymer began collaborating to develop insulation substrates for high-voltage cables. Through close cooperation between both parties, they produced insulation substrates suitable for high-voltage cables in 2011, filling the domestic gap. As the first enterprise in China to develop high-voltage cable insulation materials, Wanma Polymer continues to increase its research and development efforts in the field of high-voltage AC/DC insulation materials and insulation shielding matching, contributing to the localization process of high-voltage cable insulation materials.

The flexible DC transmission using high-voltage DC plastic cables is the mainstream direction advocated by the International Power Grid, and the development and application of high-voltage and ultra-high voltage plastic insulated DC cables have grown rapidly in recent years. However, currently only Japan and a few Western European countries are able to produce high-voltage and ultra-high voltage plastic insulated DC cables, and high-voltage cable insulation materials still need to be introduced, which creates technical barriers to the development of high-voltage cables.

At present, the development of high-voltage DC cables in China is still in its infancy, which restricts the development and application of flexible DC transmission technology. Therefore, the development of high-voltage DC cables is urgent. Only by adhering to independent innovation in the field of materials can we promote the development of the cable industry and accelerate the localization process of insulation materials used in high-voltage DC cables.