About ATPDraw:


About the Alternative Transient Program (ATP)


ATP is a universal program system for digital simulation of transient phenomena of electromagnetic as well as electromechanical nature. With this digital program, complex networks and control systems of arbitrary structure can be simulated.


ATP has extensive modelling capabilities and additional important features besides the computation of transients. It has been continuously developed through international contributions over the past 20 years.


Operating Principles


Basically, trapezoidal rule of integration is used to solve the differential equations of system components in the time domain.

Non-zero initial conditions can be determined either automatically by a steady-state, phasor solution or they can be entered by the user for simpler components.

Interfacing capability to the program modules TACS (Transient Analysis of Control Systems) and MODELS (a simulation language) enables modelling of control systems and components with nonlinear characteristics such as arcs and corona.

Symmetric or unsymmetric disturbances are allowed, such as faults, lightning surges, any kind of switching operations including commutation of valves.

Calculation of frequency response of phasor networks using FREQUENCY SCAN feature.

Dynamic systems also can be simulated using TACS and MODELS control system modelling by itself.




Uncoupled and coupled linear, lumped elements.

Transmission lines and cables with distributed and frequency-dependent parameters.

Elements with nonlinearities: transformers including saturation and hysteresis, surge arresters, arcs, corona.

Ordinary switches, time-dependent and voltage-dependent switches, statistical switching (Monte-Carlo studies).

Valves (diodes and thyristors).

3-phase synchronous machine, universal machine.


Simulation Language MODELS


MODELS in ATP is a general-purpose description language supported by an extensive set of simulation tools for the representation and study of time-variant systems.


The description of each model is enabled using free-format, keyword-driven syntax of local context and that is largely self-documenting.

MODELS in ATP allows the description of arbitrary user-defined control and circuit components, providing a simple interface for connecting other programs/models to ATP.

As a general-purpose programmable tool, MODELS can be used for processing simulation results either in the frequency domain or in the time domain.


Supporting Routines


Calculation of electrical parameters of overhead lines and cables using program modules LINE CONSTANTS, CABLE CONSTANTS and CABLE PARAMETERS.

Generation of frequency-dependent line model input data.

Calculation of model data for transformers.

Saturation and hysteresis curve conversion.

Data modularization (for $INCLUDE).



Time-varying output in printed lists, character plots, or vector plots using separate interactive graphic programs TPPLOT, PCPLOT, PlotXY. HP-GL and PostScript also can be produced.

Postprocessing of monitored variables using MODELS and/or TACS, Fourier analysis.