Short Answer:

Extra High Voltage (EHV) and Ultra High Voltage (UHV) transmission refer to systems where electrical power is transmitted at very high voltages to carry electricity over long distances with minimal loss. EHV typically ranges from 220 kV to 765 kV, while UHV includes voltages above 800 kV. These systems are used in large power networks to move bulk electricity from generation plants to distant substations.

The main purpose of EHV and UHV transmission is to reduce power loss, improve system efficiency, and support national or regional power grids. These high-voltage levels help in saving conductor material, reducing the number of required transmission lines, and enhancing the reliability of electricity supply in growing power demand scenarios.

Detailed Explanation:

Extra High Voltage and Ultra High Voltage transmission

EHV and UHV transmission are advanced power transmission technologies used to move large amounts of electrical energy over very long distances. As electricity demand grows and power generation plants are built farther from cities, normal voltage levels (like 132 kV or 220 kV) are no longer sufficient. That’s where EHV and UHV systems come into play. By using very high voltages, they reduce energy losses and ensure stable and reliable supply.

Let’s understand each term and its significance clearly.

1. Extra High Voltage (EHV) Transmission

EHV refers to transmission systems operating in the voltage range of 220 kV to 765 kV. These lines are commonly used in large power grids to carry power between states or regions. They are preferred because of their ability to move more electricity with less loss compared to lower voltage systems.

Key features of EHV:

• Voltage Range: 220 kV to 765 kV
• Used in national grids and inter-state transmission
• Reduces I²R losses (power loss due to current and resistance)
• Suitable for carrying electricity to urban areas from distant generation plants
• Improves voltage regulation and grid stability

2. Ultra High Voltage (UHV) Transmission

UHV refers to transmission systems operating above 800 kV. Some countries like China and India use UHV lines of up to 1200 kV to transfer power across thousands of kilometers. These are the most advanced and powerful lines used in power systems today.

Key features of UHV:

• Voltage Range: Above 800 kV (AC) or ±800 kV (DC)
• Used for bulk power transmission over extremely long distances
• Helps in balancing regional electricity demand and supply
• Increases transmission capacity while reducing land usage
• Supports renewable integration by connecting distant wind or solar farms to the grid

3. Benefits of EHV and UHV Transmission

• Lower Power Loss: High voltage reduces current, and hence, lowers resistive losses in transmission lines.
• Cost Saving: Fewer lines are needed to carry the same amount of power, saving conductor material and tower costs.
• Stable Supply: High-voltage systems improve voltage regulation and reduce voltage drops.
• Grid Interconnection: Allows linking large regional or national grids, improving energy availability and reliability.
• Environmental Advantage: Less number of towers and conductors means less disturbance to land and environment.

4. Applications and Usage

• Inter-state and inter-regional power transfer
• Connecting large generation sources (thermal, hydro, nuclear) to load centers
• Integrating renewable energy sources to national grids
• Exporting electricity across borders in international energy projects

Conclusion

Extra High Voltage (EHV) and Ultra High Voltage (UHV) transmission systems are essential components of modern power infrastructure. They allow safe, efficient, and reliable delivery of electricity over long distances, which is critical as the demand for energy continues to grow. These technologies not only reduce power loss but also support better grid management, reduce costs, and enable the integration of renewable energy. As power systems expand, EHV and UHV will remain key to delivering uninterrupted energy across vast regions.