EE4004/A/B Power Systems
Lab Exercise 2 - Power System Operation and Control
A. Aims
The following are the five major aims of this exercise:
1. To study the base case power flow and voltage (without abnormality)
2. To study voltage control using a capacitor bank
3. To investigate the effects of a single line outage
4. To design the appropriate rating of a capacitor bank
5. To examine the impact of adding a new line to the system
B. Methodology
In this exercise, the PowerWorld Simulator software will be used to study power system security*. A five-bus system, shown in Figure 1, will be used to evaluate (1) the effect of line outages, and (2) the use of a capacitor bank for voltage control. The system specifications are provided in Tables 1 and 2 on a 100 MVA, 132 kV base.
Figure 1 5-Bus Power System
Notes: 1. Each line has a thermal rating of 80 MVA.
2. Each busbar shall operate within the voltage range of 0.95 to 1.04 pu.
|
Bus
|
Magnitude of
Bus Voltage
(p.u.)
|
Generation
|
Load (Inductive)
|
|
MW
|
MVAR
|
MW
|
MVAR
|
|
1
|
1.02∠0
|
|
|
|
|
|
2
|
|
|
|
60
|
30
|
|
3
|
1.04
|
100
|
|
|
|
|
4
|
|
|
|
40
|
10
|
|
5
|
|
|
|
60
|
20
|
Table 1 Bus, Generation and Load Data
|
Line
|
Impedance
(p.u.)
|
|
1 – 2
|
0.15 + j0.42
|
|
1 – 4
|
0.15 + j0.60
|
|
1 – 5
|
0.05 + j0.22
|
|
2 – 3
|
0.05 + j0.20
|
|
2 – 4
|
0.15 + j0.42
|
|
3 – 5
|
0.05 + j0.20
|
Table 2 Line Data
C. Procedures
1. Build the 5-bus power system shown in Figure 1 using the initial system data provided in Table 1 and 2.
2. Modify the line data according to the 1st letter of your surname as follows to set up your own base case.
|
Case
|
1st letter of student’s surname
|
Line to Change
|
New line data
|
|
A
|
A-K
|
Line 1 – 2
|
0.16 + j0.46
|
|
B
|
L
|
Line 1 – 4
|
0.16 + j0.66
|
|
C
|
M-Z
|
Line 2 – 4
|
0.16 + j0.46
|
3. Perform. a load flow analysis using the PowerWorld Simulator. Hint: use bus 1 as the slack bus, bus 3 as the PV-bus and the remaining buses as PQ-buses.
4. Study the base case power flow and voltage of the power system.
5. Investigate the effects of voltage control by adding a capacitor bank to bus 4. Try several sizes to determine the appropriate rating of the capacitor bank.
6. Examine the effects of a single line outage by tripping any single line in the system.
7. Investigate the impacts of building a new line in the system. Construct either a new transmission line between bus 4 and 5 or between bus 3 and 4 with a line impedance of 0.15 + j0.5 and compare the results and the advantages.
8. Compare the security* of the base case with the new system after capacitor installation AND after new line installation.
9. Comment on your results.
D. Deliverable
A report of no more than 10 pages shall cover the following:
1. Use the PowerWorld software to generate a copy of LOADFLOW results of your base case.
2. Discussions on the following topics, but not limited to:
i. The static security of the system in the event of a single line outage.
ii. The reasons for using a capacitor bank to improve voltage.
iii. The appropriate rating for a capacitor bank.
iv. The impact of the capacitor bank on security performance.
v. The effects on security and voltage due to the addition of a new line.
vi. Other operational constraints that shall be considered.
3. Final conclusions based on your results.
References
1. A. J. Wood, B. F. Wollenberg, G. B. Sheble, “Power Generation, Operation and
Control”, Wiley. (Chapter 11 Power System Security)
2. J. J. Grainger, W. L. Stevenson, “Power System Analysis”, McGraw Hill. (Chapters on Load Flow and Security)
* Power system security is the ability of the electric system to withstand sudden disturbances, such as short-circuit faults or unexpected loss of system elements. It assumes that any equipment can and will fail unexpectedly at any time, yet the system will still operate within the design limits without leading to cascading failures.