Thesis Presentation 01

1. TO MY PRESENTATION

2. Presented By
Abdullah Al Morshed Nahean

3.  In a AC transmission system, when DC is imposed to
transmit simultaneously is called Simultaneous AC-DC
transmission system.

4.  Power upgrading of transmission line.
 Power transfer enhancement without any alteration.
 Load the line close to upper thermal limit.
 Achieve the advantages of parallel ac-dc transmission.
 Improve the transient stability of power system.

5.  DC power is obtained through rectifier bridge used in
conventional HVDC.
 Then the DC Power is injected to the neutral point of zigzag,
connected secondary of sending end transformer.
 Re-convert the DC to AC by inverter bridge at the receiving
end.
 The inverter bridge is again connected to the neutral point of
zigzag, connected winding of receiving end transformer.

7.  Why we use ZigzagTransformer here ?
- To avoid saturation of transformer due to dc current.
 Where we use ZigzagTransformer here ?
- Both the sending end and receiving end transformer.

8.  Two fluxes are produced by the DC current.
 They are flowing through each of a winding in each limb of the
core.
 They are equal in magnitude and opposite in direction.
 Then the net DC flux becomes zero in each limb of the core.
 Thus the DC saturation of the core is avoided.

9.  Conductors can be loaded close to their thermal limit.
 No alterations are needed.
Such us: Conductors, Insulator Strings orTowers etc.
 The power flow does not impose any stability problem.
 Rather helps to improve stability.
 The capacity of transmission line can be increased.