HVDC Transmission System Basics, Block Diagram, Working
HVDC Transmission System:
One of the important power electronics field application is High Voltage DC [HVDC] Transmission System.
For large power transmission over long distances, the HVDC proves to be economical and efficient over High Voltage AC [HVAC] transmission system.
In this post let us see how HVDC transmission system works....
HVDC Transmission System- Block Diagram
- As shown two AC systems A and B are interconnected by the DC line.
- From the system-A three phase AC supply is first passed through a AC filter.
- The AC filters reduced the current harmonic generated by the converters from entering into the AC systems.
- Then the supply stepped up through the step-up transformer.
- This gives high AC voltage which is ready for transmission.
- The high voltage AC is converted into high voltage DC by the converters that are connected in series.
If power flows from system A to B, then converter-A operates as rectifier and converter-B operates as an inverter.
If the power flows in reverse manner (i.e., B to A) then converter-B acts as rectifier and converter-A acts as an inverter.
Normally, 12 pulse configuration is used for converter A and B to reduce the ripple voltage.
- The DC output of the converter is filtered by DC filters and smoothing inductors to eliminate the DC ripples.
- Thus ripple free high voltage DC is obtained. This high voltage DC is then transmitted over the DC transmission line.
- The DC line has +kV and -kV with respect to ground.
- This is done in purpose to balance the voltage the voltage of two transmission lines with respect to earth.
- The center point of converters A and B are earthed with one line at +kV and the other line -kV with respect to earth. This done to get the +- kV system.
- At the receiving station, the high voltage DC is again filtered and passed to converter B (which act as an inverter).
- This inverter output is stepped down, passed through AC filters. Thus the three phase AC supply is obtained at the receiver side finally.
Thanks for reading about HVDC Transmission System...
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