High-voltage direct current (HVDC) cables are electrical cables that are used to transmit electricity using direct current (DC) rather than alternating current (AC). They are typically used in high-voltage transmission systems, such as those used for transmitting electricity over long distances or across barriers such as oceans or mountains. HVDC cables are designed to operate at high voltages, typically 100 kV to 800 kV. They are usually made of copper or aluminium and are insulated with polyethene or crosslinked polyethene to prevent electrical current from leaking or causing electrical accidents.
There are two main types of High-Voltage Direct Current Cables: overhead lines and underground cables. Overhead HVDC cables are supported by poles or towers and are used for transmitting electricity over long distances, typically at voltages of 66 kV or higher. Underground HVDC cables are buried beneath the ground and are used for conveying electricity at lower voltages, typically between 4 kV and 35 kV. HVDC cables are an essential component of HVDC transmission systems, as they allow electricity to be transmitted efficiently and with minimal losses over long distances. They are also used in various other applications, including power generation, renewable energy, and electrical substations.
High-Voltage Direct Current Cables also use less material because they only need a single power line to move electricity. An HVAC connection needs three power lines to carry the same power. HVDC lines also require less land space than HVAC lines for their right-of-way. The capacitors between the active transmission lines and the earth or water around them limit the length of HVAC cables. Here are some additional points about direct high-voltage current (HVDC) cables:
Advantages:
HVDC cables have several advantages over alternating current (AC) cables, including higher efficiency, better voltage stability, greater power transmission capacity, and easier control. They are also less prone to power quality issues such as harmonics and voltage sags.
Disadvantages:
HVDC cables are generally more expensive and require more complex equipment, such as rectifiers and inverters, to convert AC electricity to DC and vice versa. They are also less widely used than AC cables, as AC is more compatible with alternating current generators and motors, commonly used in the electric power industry.
Applications:
HVDC cables are used in various applications, including transmitting electricity over long distances, connecting offshore wind farms to the grid, and interconnecting different AC power systems. They are also used in submarine power cables, which transmit electricity under the sea.
Challenges:
There are several challenges associated with using High-Voltage Direct Current Cables, such as the high cost of installation and maintenance, the need for specialized equipment and personnel, and the potential environmental impacts of the cables.
Future developments:
There is ongoing research and development in the field of High-Voltage Direct Current Cables, with a focus on improving the efficiency and reliability of the wires, as well as reducing their cost and environmental impact. There are also efforts to develop new materials and technologies, such as superconducting cables, that could further improve the performance of HVDC cables.
Lines are used because they are easier to build and fit into existing grids. For example, they can connect to the distribution system and lower the voltage. At the end of the 19th, DC and then HVDC technology began to send power from one place to another. However, few lines and amenities were built then, and many were used for testing.