PSAT (Power System Analysis Toolbox) By : H. Lotfizad

History PSAT is a Matlab toolbox for static and dynamic analysis and control of electric power systems. PSAT is written by Federico Milano , in September 2001, while he was studying as Ph.D. student at the Universita di Genova, Italy, First public version of PSAT completed in November 2002, when he was a Visiting Scholar at the University of Waterloo, Canada. Now Federico Milano is working as assistant professor at the Universidad de Castilla-La Mancha, Ciudad Real, Spain but he maintains PSAT in the spare time

Overview PSAT is a Matlab toolbox for electric power system analysis and control. PSAT includes Power Flow , continuation power flow, optimal power flow, small signal stability analysis and time domain simulation. All PSAT operations can be assessed by means of graphical user interfaces (GUIs) and a Simulink-based library provides an user friendly tool for network design.

Overview PSAT core is the power flow routine, which also takes care of state variable initialization. Once the power flow has been solved, further static and/or dynamic analysis can be performed. These routines are: 1. Optimal power flow (OPF) 2. Continuation Power flow (CPF) 3. Small signal stability analysis 4. Time domain simulations 5. Phasor measurement unit (PMU) placement.

Useful features Mathematical Models & Utilities A variety of utilities Bridges to other programs Data Format Conversion capability

Mathematical Models In order to perform accurate power system analysis, PSAT supports a variety of static and dynamic component models, as follows:

Mathematical Models Power Flow Data CPF and OPF Data Switching Operations Loads Machines Controls Regulating Transformers FACTS Other Models

PSAT utilities Simulink library for drawing networks; GUIs for settings system and routine parameters; User defined model construction and installation; GUI for plotting results; Filters for converting data to and from other formats; Command logs.

PSAT bridges to other programs PSAT includes bridges to GAMS and UWPFLOW programs. This bridges highly extend PSAT ability of performing optimization and continuation power flow analysis.

Comparison between PSAT & Other Matlab Power System Toolboxes standard power flow (PF) continuation power flow and/or voltage stability analysis (CPF-VS) optimal power ow (OPF) Small signal stability analysis (SSSA) time domain simulation (TDS) Electro Magnetic Transient analysis (EMT) graphical user interface (GUI) graphical network construction (CAD)

PSAT Users PSAT is currently used in several countries. These include: Modern Countries like : USA , Canada , England , France, Australia, Japan , Italy , Spain , Sweden , China , Norway Under developing countries like : Algery, Argentina, Brasil, Chile, Colombia, Egypt, Guatemala, Hong Kong, India, Indonesia, Iran, Costa Rica, Macedonia, Malaysia, Mexico, Nigeria, Peru, Philippines, Puerto Rico, Romania, Sudan, Thailand, Turkey, Venezuela. PSATusers around the world.

PSAT Installation 1- Download the last PSAT version : http://thunderbox.uwaterloo.ca/fmilano 2- Requirements (ver 1.2.2) : Matlab 6.5 (ver 2) : Matlab 7 3- Installation : Extract PSAT zip files in a good location Open MATLAB Add PSAT’s Path to MATLAB default path

PSAT quick tutorial PSAT Installation Launching PSAT Loading Data Running the Power flow Program Displaying Results Saving Results Settings

Launching PSAT Type psat in MATLAB Prompt >> psat This will create all the structures required by the toolbox , then opens psat GUI

Loading Data Almost all operations require that a data file is loaded. To load a file: Load only a data file : - Menu File/Open/Data File - Short cut <Ctr-d> Load a saved system: - File/Open/Saved System - Short cut <Ctr-y> To allow portability the .out files used for saving system results include also the original data which can be saved in a new .m data file. The data file can be either a .m file in PSAT format or a Simulink model created with the PSAT library. If the source is in a different format supported by the PSAT format conversion utility, first perform the conversion in order to create the PSAT data file.

Running the Power flow Program To run the power flow routine: Menu Run/Power Flow Short cut <Ctr-p> It is not necessary to load again the data file every time it is modied, bacause : The last version of the data file is read each time the power flow is performed. The data are updated also in case of changes in the Simulink model originally loaded.

Other Analysis After solving the first power flow, the program is ready for further analysis, such as CPF , OPF , … Each of these procedures can be launched from the tool-bar or the menu-bar of the main window.

Displaying Results Results can be generally displayed in more than one way, either by means of a graphical user interface in Matlab or as a ascii text file. These routines only create a text report: Standard Power flow (in a .txt , .xls or .tex file) PMU placement (in a .eig file) SSSA (Small Signal Stability analysis) (in a .pmu file) These routines create graphical output : CPF OPF

Saving Results To save actual System status in a .mat file : Menu File/Save/Current System Shortcut <Ctrl-a> All global structures used by PSAT are stored in this file which is placed in the folder of the current data file all static computations allow to create a report in a text file that can be stored and used later.

Settings The main settings of the system are directly included in the main window Base frequency Base Power Start & End Simulation Time static and dynamic tolerance Maximum number of iterations Other general settings Menu Edit/General Settings or <Ctr-k> To change the default values for some fields of the Settings structure Menu Edit/Set Default To save a customize settings , use it as default values for the next sessions Menu File/Save/Settings

Network Design Using The Simulink environment : However, Creating a CAD able to design power networks visualize the topology change the data stored in it without the need of directly dealing with lists of data. However, Simulink has been thought for control diagrams with outputs and inputs variables This is not the best way for approaching a power system network. Thus, the time domain routines that come with Simulink and its ability to build control block diagrams are not used. PSAT simply reads the data from the Simulink model and writes down a data file.

Network Design To launch PSAT library click on Simulink icon in the menu-bar, the menu Edit/Network/Edit Network or the short cut <Ctr-s>.

Tools Tools that provided with PSAT data format conversion functions user defined model routines. PSAT static data files can be converted in the IEEE Common Data Format User defined model routines provide a simple way for extending the capabilities of PSAT

PSAT Interfaces PSAT provides interfaces : GAMS and UWPFLOW, These interfaces highly extend PSAT ability to perform OPF and CPF analysis The General Algebraic Modeling System (GAMS) is a high-level modeling system for mathematical programming problems. UWPFLOW is an open source program for sophisticated continuation power flow analysis UWPFLOW consists of a set of C functions and libraries designed for voltage stability analysis of power systems

Using PSAT for analysis of Voltage Collapse Based on C. A. Canizares, “Voltage Stability Assessment: Concepts, Practices and Tools," Tech. Rep. IEEE/PES Power System Stability Subcommittee. Direct Methods for determining Saddle-Node Bifurcations (SNB) Limit-Induced Bifurcations (LIB) Continuation Power Flow (CPF) The CPF is more general than DMs CPF can be used for determining: generator reactive power limits voltage limits flow transmission limits.

CPF Settings

PSAT plot for DM & CPF Results This Figure depicts CPF nose curves as displayed by means of the PSAT GUI for plotting results system. The graphic refers to three load voltages of the IEEE 14-bus test system

IEEE 14-bus test system psat plots

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