This paper describes the modeling and simulation library for power systems si1mulation under SIMULINK environment. The different features of MATLAB Toolboxes used in the analysis of power systems are described.
Software introduces SIMULINK environment of MATLAB for implementing user friendly and future expansion. To illustrate the capabilities of SIMULINK simulation tool, a case study based on a test system is presented.
A Three Phase Power Systems :
Power systems in real applications are in the form of three-phase ac circuits. A three-phase ac power system consists of three-phase generators, transmission lines and loads.
B Generation of Three-phase Voltages:
A three-phase generator consists of three single-phase generators, with voltages equal in magnitude but differing in phase angle from the others by l20ᵒ. The three generators could be connected to one of three identical loads by a pair of wires and the resulting power system.
During last four decades’ simulation of power systems have gained more importance. A published IEEE paper discussing different approaches to modeling protective relays and related power system events indicates a variety of possible software tools that may be used for this purpose (McLaren et al. 2001). The following items summarize their most important features in protection systems simulation:
- MATLAB/SIMULINK can be used to simulate power system faults and protective relay algorithm at the same time.
- MATLAB/SIMULINK offers more possibilities in power electronics, signal processing and control
- Users can easily create new relay model with MATLAB/SIMULINK
- MATLAB/SIMULINK encompasses better graphic function tools
A. Case One-matlab Applied in Power System Block Set (PBS).
A three-phase generator rated 200 MVA, 13.8 kV, 112.5 rpm is connected to a 230 kV, 10,000 MVA network through a Delta-Wye 210 MVA transformer. At t = 0.1 s, a three-phase to ground fault occurs on the 230 kV bus. The fault is cleared after 6 cycles (t = 0.2 s). The system will initialize in order to start in steady-state with the generator supplying 150 MW of active power and the dynamic response of the machine and of its voltage and speed regulators are observed. It is observed that the terminal voltage VA is 1.0 p.u. at the beginning of the simulation. It falls to about 0.4p.u. during the fault and returns to nominal quickly after the fault is cleared.
CONCLUSIONS AND RECOMMENDATIONS
This research presents user friendly features of simulation under SIMULINK environment and various. Simulink model and MATLAB Figure windows include a “Copy” function in the “Edit” menu. This is useful for reporting results: you can simply copy and paste your models or graphical results into a Word or PowerPoint document. One can also explore other options in the MATLAB Figure window. For example, find out how add a grid, change the line type, thickness or color, change the x-axis or y-axis scales, etc. MATLAB toolboxes which can be used in power system analysis.
The user friendly features are facilitated with the use of a simple drag-and-drop and cut-and-paste approach to building the exercises with pre-defined library elements. This is very important for researches who are interested in developing and testing new for various power system applications. Application example for power systems with simulation results obtained with SIMULINK has been presented to illustrate the capabilities of the PSB.
In this project, it is also achieved to show a simplified model of a power transformer simulated and different kinds of faults applied on it. The frequency components and the harmonics of the FFT signals of all of the simulated faults are extracted and saved as special indexes. The indexes are saved in the database and could be compared with any kind of similar transformer for finding the short circuit fault’s location. This method can also be used for other kinds of internal winding faults too.
Authors: Tawanda Mushiri | Charles Mbohwa