What is HVDC
High voltage direct current this is widely used in electric power systems, long-distance transmission can be done effectively by this method, it can also be used to interconnect asynchronous power systems. A recent development in HVDC is by the use of the semiconductors and it has made the voltage source converter based high voltage direct current and it has some advantages over the conventional type HVDC such as short circuit current reduction control on active and reactive power…
What is HVDC light technology
In this HVDC light converters are used for faster and efficient conversion of power. It is a new technology which is developed recently, it can be used for medium to small scale transmission purpose. It can achieve improved power quality and power flow control. By the use of extruded DC cables, it can be used for long distance transmission
Advantages of HVDC light
- It is environment-friendly
- Power transmission through underground cable can be done
- It can do underwater transmission
- It can cover long distance
- Neutral electromagnetic fields
- Oil-free cables
- Compact converter station
- It can increase the reliability of the power grid
- It can control both active and reactive power
- It can keep the voltage and frequency stable
- Feeding of power into passive networks
- Power quality control
- Compact design
- Short delivery time
- Unmanned operation
- Robust against grid alterations
HVDC light principle
The main part of the HVDC light converters are the IGBT, it has an IGBT valve bridge and because of that no converter transformers are needed between the valve bridge and the AC grid, if the DC voltage does not match the AC system voltage then a normal AC transformer can be used in addition to the reactor, this technology has developed based on the “voltage source converters” in conventional HVDC phase commuted converters are used but with the introduction of the high switching frequency component such as IGBT, voltage source converters were needed.
The difference between phase commutated converter and the voltage source converters are the VSC needs the component which can switch off the current but in PCC it only does the switch on of the current so that the VSC technology can be used to supply passive networks
Advantages of HVDC light cables over AC underground cables
- Only two cables are required between each converter station for DC cables
- There is no technical limit due to reactive power so the long-distance transmission can be done
- The DC power cable is capable to carry 50 percent more power than the equivalent AC cable
- DC cables have longer life expectancy than AC cable because of its lower operational stress
- Cable faults are rare in DC as compared to AC