Difference between HVAC and HVDC Transmission Systems
Table of Contents
Difference between HVAC and HVDC Transmission Systems
Electricity is generated at generating plants, from which it is sent over great distances to be used at load points. Considering that a gearbox conductor is use to transmit electrical power. Therefore, some power loss occurs during the gearbox as a result of the line parameter.
Therefore, we must take the necessary steps in order to reduce the power loss during the gearbox. To increase the gearbox voltage to higher values is one of them.
In order to cut down on transmission line losses, line voltage is crucial. Reduced line current and consequently lower power losses result from raising the line voltage.
Since we use both AC (alternating current) and DC (direct current) as our electric sources. As a result, two types of high voltage electrical transmission systems are distinguished:
- HVAC (High Voltage Alternating Current) Transmission System
- HVDC (High Voltage Direct Current) Transmission System
So This article will explain the main distinctions between HVAC (High Voltage Alternating Current) and HVDC (High Voltage Direct Current) transmission systems. Let’s start by giving a brief introduction to HVAC and HVDC systems.
What is HVAC Transmission?
High Voltage Alternating Current is referred to as HVAC. High voltage alternating current (HVAC) gearbox is when the gearbox system’s supply voltage is between 33 kV AC and 230 kV AC.
The power produced is increased to high voltages and then transmitted via transmission lines in the HVAC system. The three phase electrical power transmission requires at least three line conductors. The HVAC voltage transformation, on the other hand, is quick and low-cost.
What is HVDC Transmission?
High Voltage Direct Current is known as HVDC. So HVDC (High Voltage Direct Current) transmission systems are a type of high voltage transmission system where power is transmitted in the form of DC at a voltage between 100 kV and 800 kV.
In this system, electrical power generated in the form of AC is converted into DC by rectifiers, sent through HVDC lines, and then converted back into AC at the point of use. So The main benefits of HVDC are its relatively low power losses over long distances and the fact that it only needs two conductors for transmission.
Difference between HVAC and HVDC Transmission
Power transmission uses both HVAC and HVDC extensively. The following table, however, highlights several Difference between HVAC and HVDC Transmission Systems.
| Basis of Difference | HVAC Transmission | HVDC Transmission |
|---|---|---|
| Full form | HVAC stands for High Voltage Alternating Current. | HVDC stands for High Voltage Direct Current. |
| Description | A transmission system that transmits AC power at voltage about 33 kV to 230 kV is known as HVAC transmission system. | A transmission system that transmits DC power at a voltage about 100 kV to 800 kV is known as HVDC transmission system. |
| Number of conductors | HVAC transmission system requires at least three line conductors. | HVDC system requires two conductors in bi-polar system and one conductor in a monopolar system. |
| Transformer | In HVAC, transformer is used for voltage transformation. | In HVDC, transformer cannot be used, because the transformer does not work on DC. |
| Rectifier and inverter | HVAC does not require rectifiers and inverters. | The rectifier and inverter are the crucial components of an HVDC system. |
| Voltage transformation complexity | HVAC involves simple voltage transformation. | The voltage transformation is complex in case of HVDC. |
| Suitability | HVAC transmission systems are suitable for distances less than 600 km. | HVDC transmission is suitable for high power transmission at long distances, typically more than 600 km. |
| Corona loss | In HVAC, the corona loss is more. | HVDC has comparatively less corona loss. |
| Skin effect | Due to uneven current density, there is skin effect in HVAC system. | In HVDC, current density is uniform in the conductor, there is no skin effect. |
| Conductor diameter | HVAC requires a conductor of large diameter due to skin effect. | HVDC requires a conductor of relatively smaller diameter. |
| Right of way | The right of way is broader for HVAC. Right of way is the strip of land required for installation of transmission lines. | The right of way is narrower for HVDC. |
| Tower size | The tower of HVAC system are tall. | HVDC requires small sized towers. |
| Submarine power transmission | HVAC is not preferred for submarine power transmission because of stray capacitance of cables. | HVDC is preferably used for submarine power transmission. |
| Interference | HVAC causes interference with the neighboring communication lines. | HVDC does not cause interference with the nearby communication lines. |
| Circuit breakers | The HVAC circuit breakers are less expensive and have simple design. | The HVDC circuit breakers are comparatively expensive and have complex design. |
| Utilization of conductor capacity | In HVAC system, almost 30% of conductor capacity is wasted due to AC peak ratings during the delivery of average power. | HVDC system utilizes full conductor capacity. It is because in case of DC, the peak and average ratings are same. |
| Cost | HVAC is a less expensive system for power transmission. | HVDC system is little expensive than HVAC. |