High Voltage Direct Current (HVDC) is a technology used to transmit electricity over long distances using direct current (DC) instead of alternating current (AC). This method is more efficient for long-distance transmission because it reduces energy losses that occur in AC systems. HVDC is particularly useful for connecting renewable energy sources, such as wind farms and solar power plants, to the electrical grid. HVDC systems consist of converter stations that change AC to DC and vice versa. These systems can also help stabilize the grid by allowing for better control of power flow between different regions. Additionally, HVDC can connect asynchronous power systems, enabling them to work together effectively.