MODELLING AND SIMULATION                                                                                  Spanish version

Modelling and simulation

The planning, design, and operation of industrial and commercial power systems require engineering studies to evaluate existing and proposed system performance, reliability, safety, and economics. Studies, properly conceived and conducted, are a cost-effective way to prevent surprises and to optimize equipment selection. In the design stage, the studies identify and avoid potential deficiencies in the system before it goes into operation. In existing systems, the studies help locate the cause of equipment failure and mis-operation, and determine corrective measures for improving system performance.

Power system studies provides you with the information necessary to upgrade and maintain your power delivery infrastructure. The results focus on reducing operating costs, improving efficiency, increasing reliability and improving system maintainability. This studies might be classified in a great umber of way: operational conditions, time regime of the phenomenon dominant, or terminal conditions.

The complexity of modern industrial power systems makes studies difficult, tedious, and time-consuming to perform manually. The computational tasks associated with power systems studies have been greatly simplified by the use of digital computer programs.

Professor Francisco M. Gonzalez-Longatt since 1995 has stated research in modelling and simulation. This research have led to development of several power system analysis program.

First power system analysis program, PCC. This program was developed in 1994-1995 during the end career project of Professor Francisco M. Gonzalez-Longatt. It was a program developed in C++ for D.O.S in personal computer. It calculate load flow and short-circuit. Short-circuit is performed using the bus impedance matrix. Load flow calculation are made by simple Gauss-Seidel algorithm. The input data is formatted in .txt format and output presented in screen or saved in .txt format. This program was useful for several years and used in a lot of end career projects.


ASP Program. In 2001 the Professor Francisco M. Gonzalez-Longatt decided the development of a full graphic program with a good interface graphic friendly to users. This is the origin of the program called: ASP. ASP is the abbreviation of Analyzer of Power System (in Spanish: Analizador de Sistemas de Potencia). This program is a windows base application full graphic to power system analysis. The first stage of the project started in 1999 with a conceptual structure and general ideas for algorithm and data base. The final prototype was ended in 2002. This program is completely developed in Delphy programming language.

Today ASP include the most important power system analysis: load flow, short-circuit (ANSI C57, IEC 60909), transient stability (several model of excitation and governor systems), great data base of typical parameter of transmission lines, generators, motors, cables, transformer, etc.

 For more information about ASP, follow the following link.

If you are interested in  more detailed information of this project visit: Development of a power system analysis program, Design and implementation of  computational module for the analysis of transient stability of power systems into ASP program, Implementation of a computational module for short ANSI circuit calculation software for ASP (Analyzer Power Systems) Program"




MCCL. In 2003, the Professor Francisco M. Gonzalez-Longatt decide develop a program, included into ASP program as a module), to calculate the electrical parameter (resistance, impedance series and admittance shunt) in transmission lines. Tris program is called "MCCC" Program for Line Constant Calculation (MCCCL in spanish: Modulo de Calculo de Constantes de Lineas").

This program compute the self and mutual coupling impedances of overhead lines and to do so for realistic combinations of circuits in dense or sparse rights-of-way. The program in fully graphics and allow any number of circuit and ground cables, considering transposition or not. Furthermore, the program consider the resistivity of the soil in unbalanced conditions (not available in demo version). The result could be stored in a database used Microsoft Access.

If you are interested in  more detailed information of this project visit: Implementation of a computational module for short ANSI circuit calculation software for ASP (Analyzer Power Systems) Program"



MCCC. A great evolution of MCCL was development of MCCC in 2003. MCCC is the abbreviation of Program for Electric Parameter Calculation in Power Cables (in Spanish MCCC: Modulo de Calculo de Constantes de Lineas). 

MCCC program perform calculation of the self and mutual coupling impedances in underground power cables distribution systems. This program has a powerful graphic interface. It permit the use of user define parameter to provide flexibility in the calculations. A comprehensive database of power cables are included and results could be saved in the database.

If you are interested in  more detailed information about this project visit: Implementation of a computational module for short ANSI circuit calculation software for ASP (Analyzer Power Systems) Program"


SimSP is a complete program for power system analysis with research purposes. This program was developed using Matlab language by Professor Francisco M. Gonzalez-Longatt. SimSP is the abbreviation of Power Sistem Simulator (in Spanish Simulador de Sistemas de Potencia). This tool has been developed for research purpose for this reason no graphic interface was considered. In fact, the main contributions are in modelling and simulation. The input and output of this program are formatted in Microsoft Excel. This program was developed to considerer de main aspect of fundamental frequency operation, for this reason all results are provided in this way, rms values of main variables (full configurable, depending on wich study is carried out). Furthermore, fundamental frequency studies implies a los of supposition admitted in this program. capacities of this program involve the following studies:

Load flow. A full load flow routine is included in this program. Load flow equations are formulated in polar form. The network is modelled by an admittance matrix. Model of under load tap changer, shut compensation, voltage dependence of the static load and other elements are included. Single cage induction machines are modelled with steady state model, considering completely the voltage dependence and including the slip as variable into the power flow solution. A Newton-Raphson iterative technique is used for the load flow solution. Reactive power generation limits in generator are included into the program. This program include the possibility of model wind turbines, using a power coefficient Cp, and considering the wind speed. A further development include in this routine is the detailed wind park simulation considering the wind speed variation caused by turbulence between turbines. A complete report of load flow calculations is formatted in Microsoft Excel.


Short-circuit. This module of SimSP is used to calculate the current and voltages during a tri-phase fault. A impedance matrix was used for short-circuit calculations, considering sparse techniques. Model of inductions generators was included in this program, and inverter fed power into the power system.


Transient stability. The transient stability program enables accurate model for power system dynamics simulation  and permit simulate system disturbances and events. The main disturbance is tri-phase short-circuit but the program might simulate load rejections, changes in adjust of power or voltage or any variable, outages of transmission lines, etc. This program include a   complete models of: synchronous & induction machines, excitation system, governor-turbine models, etc. SimSP is different to the conventional transient stability program because include the models of most important new technologies:

Micro turbines (simple-shaft and slit-shaft)


Fuel cells (SOFC and PEMFC)


Wind turbines (constant and variable speed speed). In wind power generation, a detailed models of wind turbines include: shaft, pitch angle control, model of double fed induction generator including electronic power converter, single cage induction generator.

The transient stability program is based in partitioned explicit method to resolve de differential algebraic model of the power system. the algebraic equations are resolved by a Newton Raphson iterative technique. The set of differential equations are resolved using a Modified Euler methods. The magic in this program is in the way of programming. An open programming is based in black box principle. Just inputs and outputs. This vision permits add more devices in a easy way.


Voltage stability. A implementation of the Continuation Method for voltage stability analysis including reactive power generation was used in this program. Tap Changer Limits was not considered. This is a first version of the program for the voltage security assessment of power systems. this program assess the voltage stability of a power system by means of the two most common static voltage stability analysis techniques:  P-V Analysis (P-V Curves) and V-Q Analysis (V-Q curves). Modal analysis is coming soon. 

For more information about SimSP go to the project PhD Thesis of Professor Francisco M. Gonzalez-Longatt.


FluPot. This is a program developed using Matlab programming language in 2006. It permits the load flow calculations in more complex way. The load flow formulation was bead in polar form and the set of equations is resolved using Newton-Raphson iterative methods. The main contributions of this program are: (1) include a complete model in steady state of single cage induction machine (operation as motor or generator), (2) consider the model of wind turbines, (3) it program consider a model of a complete wind park (including the effect of turbulence between turbines, because consider the exact location of each wind turbine into the wind park). FluPot is the abbreviation of power flow (in Spanish "Flujo de Potencia").

This program was developed in Matlab, without graphic interface. The main purpose of this program is research for this reason input and output are formatted in Microsoft Excel. This program is based in:

[1] J. Cidrás, J. A. Martínez, J. A. Peças, and F. P. Maciel, “Modelling of Nonlinear nodal Admittances in Load Flow Analysis”, in Proceedings of IFAC, Artículo Técnico,1992

[2] J. Cidrás, José A. Martínez V., Joao Pecas L. y Maciel Barboza. (1991). “Simulation of MV distribution networks with Asynchronous local Generation Sources

For more information about Flupot go to the project Design and develop of software to load flow calculation including the model of wind farms


LFRGD. This is a load flow program developed for distribution network, considering the typical characteristics of it (low X/R ratio, typically radial). LFGCD is a load flow program programmed in Matlab for distribution system including the integration of distributed generation. A compensation-base power flow algorithm was used in this program because provide a good performance for weakly meshed distribution and transmission systems. This program was developed for research. Inputs are outputs are formatted in Microsoft Excel. The main contribution of this program is a robust algorithm for radial distribution network, fast and easy to programming. This program is based in:

[1] Hong H. y Shirmohammadi D. “A Compensation-Based Power Flow Method for Weakly Meshed Distribution and Transmission Networks”. IEEE Transactions on Power Systems, Vol. 3, No. 2, Mayo, 1988.

If you are interested about more detailed information of this project visit: Design and development of computational tool in MATLAB™ for load flow calculations in distribution network including distributed generation


CurvasRemi is a Matlab base program developed in 2007 by Professor Francisco M. Gonzalez-Longatt. This program provide a complete evaluation of the steady state performance for a simple induction machine. This program provide several operating point of the induction machine (motor and generator operation mode). A complete set of characteristics curves are plotted with this program: torque, active power, reactive power, current, power factor efficiency (all variables versus slip). The program is configurable for evaluation of dependence of the characteristic curves of main variables versus voltage in terminals.

This program was developed in Matlab. The input and outputs are available in screen. for more detailed information review: "Program to plot of characteristics curves of single cage induction machines in steady stated: CurvasRemi: Validation


26th April  2009.


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