Assignment 5
Due date: 18-03-2014
Problem 1:
Consider 4-bus bipolar DC network. Here, each bus indicates a unit of three nodes corresponding to Pole 1, Pole 2 and Neutral, respectively. Likewise, each line also consists of three conductors.
The resistances of both the pole conductors are same for any line, whereas, the resistance of a neutral conductor is half of the resistance of corresponding pole conductor. The description of the DC network is shown in Table 1.
Line id. From bus
TL1 1
TL2
TL3
TL4
2
3
4
TL5 4
To bus
2
3
4
1
2
Table 1
DC Network Description
Pole conductor resistance
5 Ω
8 Ω
6 Ω
10 Ω
5 Ω
There are four converter stations located at Buses 1, 2, 3 and 4, respectively. For all the converter stations, the AC bus voltage (L-L, rms), transformer transformation ratio and commutation equivalent resistance are 400 kV, 1:1 and 5Ω, respectively. The firing angles of the different converter stations are shown in Table 2.
Converter id.
CONV1
CONV2
CONV3
CONV4
Table 2
Converter Station Firing angle
Bus
1
2
3
4
Firing angle
20
0
15
0
150
0
155
0
For each converter station, find out,
1.
Converter current (for each pole).
2.
Converter terminal voltage (for each pole).
3.
The active power drawn from the grid.

4.
The reactive power drawn from the grid.
5.
Commutation overlap angle.
In addition, find out the current through each line (for each pole) of the DC network.
Items Deliverable:
Complete solution with detailed procedure done with pen and paper.