DC Transmission System About


Dear reader, Today we will know about the DC distribution system. How DC output is transmitted from production to customer level.

Things that will be discussed,,,,
  1. Introduction:-

  2. Descrive the High Voltage DC Transmission System:-

  3. State the Limitations of AC Transmission:-List the Advantage of HVDC:-

  4. List the Disadvantages HVDC:-

  5. Types of HVDC Transmission system:-List the Fields of Application of HVDC:-

  6. List the Fields of Application of HVDC:-



Why HVDC is needed? The answer to this question will probably reveal the technical issues of HVDC. It is historically proven that the amount of copper, insulation cost, power wastage, and the AC more expensive and better than the AC to send the equivalent amount in the distance. Moreover, due to the effect of the frequency of the DC system, there is no adverse reaction to inductance and capacitance on line cable. Again, HVDC can be easily launched, stopped, and controlled compared to HVAC. Therefore, there is no alternative to HVDC for detection and hassle-free operation. The electricity sector is currently using HVDC instead of the developed world HVAC. In the AC system where three conductor is required, the DC system requires two (positive and negative) ones. So the system takes less amount of conductor and uses relatively light and narrow towers. Currently DC transportation up to 400 KV is possible.

Descrive the High Voltage DC Transmission System:-

The picture below shows a single diagram of the transmission system. Electricity produced at the center of the production from the image, the voltage generated with the help of step-by-step transformer is increased. Along with the Mercury Arch Rectifier, it is transmitted to the transmission line by transferring it to the DC. On the other hand, on the receiving side of the transmission line, DC is changed using the Thayeratron. And with the help of the step down transformer the voltage is reduced to acceptable means. Then the electricity is transported and distributed through a distributor in a similar feeder to the AC system.

State the Limitations of AC Transmission:-

  • AC transmission takes more than copper in comparison to the DC.
  • The AC transmission line process is much more complex than the DC transmission.
  • Due to the effective effect of the line due to the skin effect in the AC system, the increase in resistance and line loss increases.
  • The capacitance effect is always observed in the AC system.
  • There is a lot of synchronization and stability problems in AC transmission system than DC.
  • Because the response to inductance comes on the affected, the nearest communication affects the circuit.
  • Charging current increases with the increase in the voltage on the AT and so the transmission of high voltage carrying multiple conductors is not possible after dragging.


List the Advantage of HVDC:-

  • For a long transport line, two-thirds of its cop should be saved in its DC system compared to its ow.
  • Power dissipation at HVDC is less than 29% compared to the SI.
  • In addition to the addition of additional equipment, 41% more power is sent to HVDC.
  • Due to high voltage resistance in the DC, the insulation level is only 87%.
  • It is more convenient to link HVDC instead of AC interconnection to two different voltage / frequency generating stations.
  • AC interconnection is controlled by a painful way of having normal or unusual moments with Phase Relationship.
  • The long HVDC overhead line and the short-lived cable system, the origin and exploitation of the reactive power can be seen.

List the Disadvantages HVDC:-

  • Rectifier and inverter is needed as an additional device.
  • The cost of the sub-station increases.
  • The control system is complex and costly.
  • According to the requirement the voltage is not easy to be more or less.
  • Transfer is not easy.
  • High quality DC circuitbreaker is inelastic and high priced.
  • The biggest problem with the DC system is that the transformer can not be used in this system.

Types of HVDC Transmission system:-

According to the system management or interconnection system, the entire HVDC link can be classified as follows

(1) Bipolar System:

  • Two poles, one positive with respect to earth and other negative.
  • Pole includes subsection pole and transmission line pole.
  • The midpoint of Bipoles in each terminal is earthed Via an electrode line and an earth electrode.
  • Earth electrodes located about 5 to 25 km away from terminals.

(2) Monopolar System:

  • On pole and return earth.
  • Earthing of poles Via electrode line and earth electrode.
  • Earth electrode located away from terminal substation.
  • The pole is normally negative with respect to earth.

(3) Homopolar System:

  • The two poles and returns completed with the same polarity comprise the system of homopollars in the Earth’s crossover.
  • Two poles of same polarity and return earth.

(4) Back to back HVDC coupling System

  • Usually Bipolar without return earth.
  • Reference earth provide for protection, controls, measurements.
  • Convertor and inverter located in the same substation.
  • No HVDC transmission line.
  • Two AC systems linked by a single HVDC Back to back coupling station.

(5) Multi terminal HVDC system:

  • Three or more terminal substations.
  • Bipolar
  • Some terminals feed power in HVDC bus, some receive power from HVDC bus.

List the Fields of Application of HVDC:-

  • For sending high power over long distances.
  • For short distance supply for high power and to supply via Underground cable.
  • Interconnection of substations or back to back.
  • Regarding the change in the frequency of the frequency.
  • In the case of telecommunication.
  • The big line of the city is on the line.
  • To keep the submarine cable free from the charging current.


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