ELEC5204 Power Systems Analysis and Protection
Unit Assignment
February 20, 2025
1 Short Circuit Analysis
This assignment is to be completed in Matlab and Simulink. Please use Matlab version 2022b or later to avoid any issues with compatibility.
Upload your finalised Simulink model, Matlab scripts, and report as a zip directory to Canvas for submission. The report should briefly describe the steps used to solve each problem and present the results of hand calculations and simulation results. Please also provide the version of Matlab used to obtain the solution.
Part 1 System Modelling and Power Flow Calculation
Suggested time to complete: 2 weeks
Build the 7-bus network shown in the Figure 1.1 below in Simulink.
Figure 1.1: Single-line diagram of a 7-bus power system (Figure 6.27 in Power Systems Analysis and Design, 6th Edition by Glover, Overbye, and Sarma).
Use L2 = 20km.
The diagram has been started for you (see Project 7bus Assignment.slx). The system parameters defined in 1.1 can be found in the Matlab script provided (assignment parameters.m).
Generators have been modelled as ideal voltage sources. All transmission lines should be modelled as pi sections and loads as three-phase parallel RLC loads.
Solve the power flow problem on the completed system using the Load Flow Analyzer in the powergui block. This should result in approximately the following bus voltages and angles in per-unit:
Bus 1: 1∠0。
Bus 2: 0.9243∠ - 34.38。
Bus 3: 0.9179∠ - 34.52。
Bus 4: 0.9167∠ - 34.12。
Bus 5: 0.9196∠ - 33.34。
Bus 6: 0.9260∠ - 32.61。
Bus 7: 0.9663∠3.165。
Note that the three-phase fault block is not yet needed and can be commented out.
Briefly comment on the results of the power flow calculation in your report. The completed model will be used to perform fault simulations in the following two sections.
Part 2 Symmetrical Faults
Suggested time to complete: 3 weeks
Calculate the magnitudes of the bus voltages and branch currents resulting from a three-phase-to- ground fault at:
(a) Bus 1
(b) Bus 4, and
(c) Bus 5
Convert all pre-fault loads to constant admittances using the pre-fault bus voltages. Include all impedance parameters (i.e., include line resistances and shunt capacitances). Assume all faults are bolted.
It is recommended that the solution be obtained via calculation using Matlab. Describe the process used to obtain the solution in your report.
Simulate the above faults using the Simulink model created in Part 1. The pre-fault conditions will first need to be initialised by computing the load flow solution as done previously.
Check the calculated values against the Simulink model and comment on any differences in your report. Note that there may be minor differences between the calculated values and those obtained through simulation - however, answers should still be within ±5%.
Part 3 Unsymmetrical Faults
Suggested time to complete: 3 weeks
Calculate the voltage magnitude for each phase at:
(a) Bus 1, and
(b) Bus 6
for a single line-to-ground fault occurring at Bus 5. Assume that the fault is bolted and occurs on Phase A in both cases.
It is recommended that the solution be obtained via calculation using Matlab. Describe the process used to obtain the solution in your report.
Simulate the above faults using the Simulink model created in Part 1. The pre-fault conditions will again need to be initialised by computing the load flow solution.
Check the calculated values against the Simulink model and comment on any differences in your report.
Part 4 Finalise Report
Suggested time to complete: Along the way and never leave it to the last day
Finalise the report describing the methodology and results from Part 1, Part 2, and Part 3.