Introduction to Extra High Voltage Cables
Extra-high voltage English abbreviation UHV; voltage symbol is U (individual places with V expressed); the unit of voltage is Volt, the unit symbol is also V; than the volts of kV (kilovolts), than the volts of mV (millivolts), uV (microvolts), between them is a thousand into the bit. In our country, extra-high voltage refers to the voltage level of ± 800 kV and above DC and 1000 kV and above AC. The voltage levels in our country are roughly divided into five categories: low voltage, medium voltage, high voltage, ultra-high voltage and extra-high voltage. Extra-high voltage is the most advanced power transmission technology in the world.
In our country, ultra-high voltage refers to ± 1000Kv and above AC and ± 800Kv and above DC transmission constitutes ultra-high voltage, ultra-high voltage is generally used in the West-East transmission and other ultra-long-distance transmission of voltage channels. Extra-high voltage is one of the few major independent innovations in China and a world leader. Extra-high-voltage cable usually refers to the cable that transmits 35-1000KV power, which is a kind of technical object capable of transmitting power over long distances, and it has a lot of advantages.
In the field of power transmission, UHV cables belong to the existence of high technology, without it, the whole infrastructure field should be affected. UHV cables are capable of sustained power transmission, for example, in some remote places, through UHV cables, can meet the basic power supply needs, and can ensure stability. At the same time, it also has higher economic benefits because of lower cost and lower power loss.
Simply put, it is a cable capable of high voltage power transmission. Nowadays, in infrastructure, industrial parks and other places may need to use it, so it is used in a very wide range, and our lives are closely related.
The construction of extra-high voltage cable:
Conductor: usually use multi-stranded stranded copper or aluminum conductor to improve electrical conductivity and mechanical strength.
Insulation: UHV cables are made of cross-linked polyethylene (XLPE) and other high-performance insulating materials, which are capable of withstanding high voltage and prolonged electrical stress.
Shielding layer: Used to balance the electric field distribution, reduce corona discharge and electromagnetic interference.
Sheathing layer: protects the cable from the external environment, such as waterproof, UV protection and chemical erosion.
Reinforcements: including armoring or reinforcing fibers to increase the mechanical strength and tensile properties of the cable.
Ultra-high voltage cables (UHV cables) play a central role in power transmission systems and are mainly used in the following key areas:
Power system backbone network
National and regional power grids: UHV cables are used to connect large power stations (e.g. nuclear power stations, large hydroelectric power stations, thermal power stations, etc.) and major load centers, realizing the efficient transmission of ultra-long-distance, large-capacity power.
Cross-area power transmission network
Across districts, provinces and countries. It is used for power transmission across all geographical barriers (such as mountain ranges, rivers, straits) and national boundaries to realize the optimal inter-regional allocation of energy.
Urban power infrastructure:
Urban Underground Cable Networks: in densely populated urban centers, extra-high voltage cables are used for underground transmission of electricity to save ground space and reduce visual pollution while improving the stability and security of the power supply.
Renewable energy integration
Wind farms and photovoltaic power stations: UHV cables are used to efficiently transmit power generated by wind and solar power stations far from load centers to the power grid, and are a key link in realizing the large-scale use of renewable energy.
Smart Grid Construction
Grid automation and remote monitoring: UHV cables not only transmit power, but also carry data communication, supporting real-time monitoring, regulation and maintenance of smart grids.
Transportation Infrastructure
High-speed rail and urban rail transit: UHV cables provide reliable power supply for high-speed trains and urban subways, supporting high-density, high-speed public transportation systems.
Industrial Power Supply
Large industrial zones: In industrial zones that require large amounts of power, UHV cables provide a stable power supply to support the production activities of heavy industry, chemical industry, iron and steel, and other high energy-consuming industries.
Cross-sea power transmission
Submarine cables: UHV cables are used for cross-sea power transmission, connecting islands to the mainland power grid, or enabling cross-border power trade.
Emergency and backup power
Military installations and critical institutions: In national security and strategic installations, UHV cables ensure the reliability and continuity of critical power systems.
UHV cables are playing an increasingly important role in the global power system due to their high efficiency and low loss characteristics, especially in driving the clean energy transition and improving the overall efficiency of the power system. As technology continues to advance, the application areas of UHV cables are expected to expand further and become a key component of future power grid construction.
Advantages of extra-high voltage cable
UHV cable is a kind of ultra-long-distance power transmission technology, which has many advantages such as long distance, large capacity, high efficiency, low loss, low unit cost, and land occupation, etc. It can effectively solve the problem of ultra-long-distance and ultra-large-scale transmission of energy. Summarized as ultra-high power, ultra-long distance power delivery, while the loss can be reduced to very low. Can effectively solve many problems, laying costs will be higher, but the extra-high voltage in the country in 2020, the new infrastructure of the seven major areas of the list, see the construction of extra-high voltage is still imperative.
Extra-high voltage cable transmission mode
Extra-high voltage transmission mode can be divided into DC transmission and AC transmission according to the different scenarios of use. DC transmission refers to only point-to-point transmission, the center can not fall point, transmission power, distance, suitable for long-distance power transmission. AC transmission refers to the middle of the grid can fall point, transmission capacity, wide coverage, lines in series, network structure, can be both transmission and network functions, suitable for close-distance power transmission. Because in the ultra-high voltage within 800 kilometers are more cost-effective AC power, more than 800 kilometers DC power is cheaper, so the distance is close to the time when the AC transmission, once across the province and other ultra-long distance, DC transmission is more cost-effective and safe.
Extra-high voltage cable technology features
(1) UHV DC transmission system does not fall in the middle of the point, point-to-point, high-power, long-distance power sent directly to the load center. In the case of a clear relationship between sending and receiving, UHV DC transmission is used to realize AC/DC parallel transmission or non-synchronous networking, and the grid structure is relatively loose and clear.
(2) UHV DC transmission can reduce or avoid a large number of over-grid currents, and change the currents in accordance with the changes in the operation mode of the sending and receiving ends. The direction and size of the current of the UHV DC transmission system can be easily controlled.
(3) UHV DC transmission has high voltage, large transmission capacity and narrow line corridor, which is suitable for high-power and long-distance transmission.
(4) In the case of parallel transmission of AC and DC, the use of DC active power modulation can effectively inhibit the power oscillation of AC lines in parallel with it, including regional low-frequency oscillation, and significantly improve the transient and dynamic stability of AC.
(5) High-power DC transmission, when the DC system blocking occurs, both ends of the AC system will be subjected to large power impact.
Extra-high voltage cable transmission technology advantages
UHV transmission technology has the following significant advantages:
(1) High transmission capacity: UHV transmission technology can realize higher transmission capacity under the same transmission distance, which is conducive to the scheduling and utilization of large-scale power resources.
(2) Long-distance transmission capacity: UHV transmission technology can realize long-distance power transmission, which is helpful to solve the problem of power transmission between resource-rich areas and demand-concentrated areas.
(3) Low line loss: by increasing transmission voltage and adopting high-performance conductor materials, UHV transmission technology can reduce line loss and improve the efficiency of power transmission.
(4) Saving investment costs: Since UHV transmission technology has higher transmission capacity and long-distance transmission capability, it can reduce the number of transmission lines, thus lowering investment costs.
(5) Reducing the occupation of land resources: UHV transmission technology can realize higher transmission capacity and long-distance transmission capability, thus reducing the number of transmission lines and the occupation of land resources.
Technical and Economic Advantages of Extra High Voltage Cables
The main technical and economic advantages of UHV DC transmission compared with UHV DC at ±600 kV level and below 600 kV can be summarized in the following six aspects:
I. Large transmission capacity. Using 4000 ampere thyristor valve, ±800 kV DC UHV transmission capacity can reach 6.4 million kilowatts, which is 2.1 times that of ±500 kV and 3 million kilowatts high-voltage DC mode, and 1.7 times that of ±600 kV level and 3.8 million kilowatts high-voltage DC mode, and it can give full play to the advantages of scale power transmission.
II. Long power transmission distance. The use of ± 800 kV DC transmission technology makes it possible to send power over long distances, and the economic transmission distance can reach 2,500 kilometers or even more, providing transmission guarantee for the development of large hydropower bases in Southwest China.
Three. Low line loss. In the case of the same total cross-section of conductor and transmission capacity, the resistance loss of ±800 kV DC line is 39% of ±500 kV DC line and 60% of ±600 kV DC line, which improves the transmission efficiency and saves the operation cost.
IV. Save engineering investment. According to the calculation of the relevant design departments, for ultra-long distance, large capacity transmission needs, ± 800 kV DC transmission program unit transmission capacity of the comprehensive cost of ± 500 kV DC transmission program is about 72%, saving engineering investment benefits.
V. High corridor utilization. The line corridor of ± 800 kV, 6.4 million kW DC transmission scheme is 76 m, and the transmission capacity per unit corridor width is 84,000 kW/m, which is about 1.3 times as much as that of the ± 500 kV, 3 million kW scheme and the ± 620 kV, 3.8 million kW scheme, which improves the utilization efficiency of transmission corridors and saves valuable land resources; and due to the large transmission capacity of a single circuit line, it saves significantly on valleys, limited resources at river crossing points.
VI. Flexible operation mode. The State Grid Corporation of China’s ultra-high voltage direct current transmission is proposed to use 400 + 400 kV double twelve pulsating converter series connection scheme, flexible mode of operation, system reliability is greatly improved. Any one converter module failure, the system is still able to ensure 75% of the rated power delivery.
Extra-high voltage cable application prospects
UHV DC transmission has point-to-point, ultra-long-distance, large-capacity power transmission capability, mainly located in China’s southwest hydropower base and northwest coal power base of ultra-long-distance, large-capacity transmission.
The application of UHV DC in China has a broad prospect. To the national power grid, for example, the jinsha river a xiluodu and to the home dam send out project will be used 3 back ± 800 kv, 6.4 million kw dc uv, sichuan jinping hydropower station using 1 back ± 800 kv, 6.4 million kw dc uv, the above project is planned to be completed and put into operation at the end of 2011 ~ 2016 period. Jinshajiang River II Udongde, Baihetan hydropower station send out the project will also use 3 back ± 800 kV, 6.4 million kW DC UHV send out. The development of UHV DC transmission, but also for China’s backup energy base in Tibet hydropower and Xinjiang coal power development to provide an economical way of transmission, to strengthen the power cooperation with Russia, Mongolia, Kazakhstan and other countries to provide technical support.
Extra-high voltage cable development prospects
The construction of “ultra-high voltage national power grid to achieve optimal allocation of energy resources” as an important goal of grid construction and tasks to ensure the safe and stable operation of power supplies and power grids is of great significance. The United States, Canada, Russia, Japan, Italy, Spain and other countries from the seventies of the last century began to study the ultra-high voltage transmission technology, after more than 40 years. Nearly three or four decades in Europe, North America and other places occurred more than a dozen large-scale blackouts is the lesson that the higher the load supplied by the AC power, the larger the coverage, the more there is a huge security risk, and therefore must be closely linked to the UHV AC power grid to provide a more adequate standby capacity, the grid is very susceptible to typhoons, torrential rains, lightning strikes, ice, pollution flash, military damage and other natural and manmade disasters, if there is no adequate standby capacity, will be If there is no sufficient spare capacity, the accident will spread and expand rapidly. Therefore, in order to ensure the safe operation of the power grid, it is necessary to study the structure of the power grid in planning, design, construction and operation, and to implement the three-channel protection in accordance with the principle of “stratification and zoning”. The State Grid and the Southern Power Grid have proposed the construction of an “extra-high voltage national grid” with the goal of optimizing the allocation of energy resources.
Importance of extra-high voltage cable
Extra-high voltage itself has a large transmission capacity, long transmission distance, low energy consumption, less land occupation, and obvious economic characteristics, especially the long transmission distance is its biggest feature. Due to the uneven power resources and loads in China, more than 80% of China’s energy resources are distributed in the west and north; more than 70% of power consumption is concentrated in the east and center, and the distance between supply and demand is about 800-3000km, due to the fact that the economy of the resource-rich areas is more backward, and the population is relatively sparse, and the power generated cannot be fully consumed in those areas, and the power resources are not easy to be stored, and if there is no way to transmit them out strongly, the resources will be wasted. If there is no way to strongly transmit it out, the resources will be wasted. But in the face of such a large-scale long-distance power transmission, if the ultra-high voltage grade transmission line loss, system stability and short-circuit current problems will be very serious, so the use of ultra-high voltage transmission to solve such problems.
As an efficient and economical means of power transmission, UHV transmission technology has been widely used worldwide. With the progress of science and technology and the advancement of global energy transformation, UHV transmission technology will continue to play an important role in helping the world realize the goals of sustainable development and low-carbon economy. However, in the face of many challenges, all parties concerned need to strengthen technological innovation, optimize management measures and enhance international cooperation in order to promote the sustainable development of UHV transmission technology.
TST cables–The world’s leading manufacturer of extra high voltage cables
In the vast universe of electricity, TST cables extra high voltage cable are like a bright star, crossing mountains and all obstacles, illuminating the way forward and leading the way to a green energy future. tst cables UHV cables are reshaping the global power landscape by virtue of their extraordinary transmission efficiency, extremely low energy losses, high safety and stability, and gentle care of the ecological environment. tst cables UHV cables are the world’s leading manufacturer of power cables.It is not only the pinnacle of cable technology, but also a model of safety and environmental protection, guarding every bit of the earth’s greenery, and jointly promoting the development of the industry to achieve mutual benefit and win-win situation. If you need to upgrade cables for your equipment, or have questions or needs for XLPE cables，extra high voltage cables, high voltage cables, please feel free to send us an email, senior engineers will be happy to help you, you can also get free samples.
