Short Answer:

HVDC (High Voltage Direct Current) transmission is mainly used for long-distance power transfer, underwater cable connections, interconnecting different power grids, and integrating renewable energy sources like wind and solar. It helps in transmitting power efficiently with fewer losses compared to traditional AC systems.

The key applications include transmitting electricity over very long distances, connecting offshore wind farms to land, linking asynchronous grids, and supplying power to remote or urban areas through underground cables. HVDC is chosen where efficiency, reliability, and better control of power flow are required.

Detailed Explanation:

Applications of HVDC transmission

High Voltage Direct Current (HVDC) transmission is a modern method of delivering electrical power using direct current instead of alternating current. It is especially useful in situations where traditional AC transmission is less efficient or technically challenging. With the advancement of power electronics and converter technology, HVDC systems are now widely used in various parts of power systems across the world.

HVDC systems offer advantages like lower losses, better voltage control, and the ability to connect different types of power systems. This makes them ideal for specific applications where AC transmission is not feasible or economical.

Major Applications of HVDC Transmission

1. Long-Distance Bulk Power Transmission
   HVDC is the best solution for transmitting large amounts of electricity over very long distances (typically more than 600 km for overhead lines and 50 km for cables).

• Example: Hydro power stations located far from cities can use HVDC to send power with minimal losses.

2. Undersea and Underground Power Transmission
   HVDC is ideal for undersea and underground cables because AC transmission faces high charging current and capacitive losses in such situations.

• Example: HVDC is used for submarine cables like the UK–Norway (North Sea Link) or India–Sri Lanka power link.

3. Interconnection of Asynchronous Grids
   HVDC allows the linking of two power systems operating at different frequencies or without synchronization.

• Example: India’s Southern grid was connected to the rest of the country using an HVDC back-to-back link.

4. Integration of Renewable Energy
   HVDC is used to connect large-scale renewable energy sources, especially offshore wind farms, to the main grid.

• Example: Offshore wind power in Germany and Denmark is delivered to the mainland via HVDC lines.

5. Power Supply to Isolated or Remote Areas
   HVDC is suitable for delivering electricity to islands, hilly regions, or sparsely populated areas where building strong AC networks is difficult.

• Example: HVDC lines are used in Canada and China to supply power across remote terrain.

6. Urban Power Supply Using Underground Cables
   HVDC lines can be run underground through cities without causing electromagnetic interference and with minimal space requirements.

• Example: Underground HVDC cables are used in big cities like New York and Tokyo to avoid congestion.

7. Back-to-Back HVDC Stations
   Used where there is no need for long-distance lines but still a need to connect two different systems (e.g., different frequencies or systems).

• Example: HVDC back-to-back links are common in inter-country or inter-regional connections.

8. Grid Stabilization and Control
   HVDC systems provide fast and independent control of power flow, making them useful for stabilizing large power networks.

• They can help reduce the risk of cascading failures and support black start capabilities.

Conclusion

HVDC transmission is applied in many critical areas of power systems where efficiency, flexibility, and long-distance capability are essential. From connecting distant power sources to delivering energy across oceans and stabilizing entire grids, HVDC plays a key role in modern power infrastructure. As energy demand grows and renewable integration expands, HVDC technology will continue to be vital for future power networks.