Alternative Transients Program Features

• 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.
  
  
• Frequency-domain harmonic analysis using HARMONIC FREQUENCY SCAN (harmonic current injection method)
  
  
• Dynamic systems also can be simulated using TACS and MODELS control system modelling without any electric network.

• Uncoupled and coupled linear, lumped R,L,C elements.
  
  
• Transmission lines and cables with distributed and frequency-dependent parameters.
  
  
• Nonlinear resistances and inductances, hysteretic inductor, time-varying resistance, TACS/MODELS controlled resistance.
  
  
• Components with nonlinearities: transformers including saturation and hysteresis, surge arresters (gapless and with gap), arcs.
  
  
• Ordinary switches, time-dependent and voltage-dependent switches, statistical switching (Monte-Carlo studies).
  
  
• Valves (diodes, thyristors, triacs), TACS/MODELS controlled switches.
  
  
• Analytical sources: step, ramp, sinusoidal, exponential surge functions, TACS/MODELS defined sources.
  
  
• Rotating machines: 3-phase synchronous machine, universal machine model.
  
  
• User-defined electrical components that include MODELS interaction

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.

TACS  is a simulation module for time-domain analysis of control systems. It was originally developed for the simulation of HVDC converter controls. For TACS, a block diagram representation of control systems is used. TACS can be used for the simulation of

• HVDC converter controls
• Excitation systems of synchronous machines
• power electronics and drives
• electric arcs (circuit breaker and fault arcs).

Interface between electrical network and TACS is established by exchange of signals such as node voltage, switch current, switch status, time-varying resistance, voltage and current sources.

• 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 (Semlyen, J.Marti, Noda line models).
  
  
• Calculation of model data for transformers (XFORMER, BCTRAN).
  
  
• Saturation and hysteresis curve conversion.
  
  
• Data modularization (for $INCLUDE).

Most users, including program developers, use Intel 486/Pentium-based PC's with MS-Windows 3.x/95/98/NT. A standard PC configuration with min. 16-MB RAM, hard disk (20 MB free space) and VGA graphics is sufficient to execute ATP under MS-DOS/MS-Windows. ATP is available for other computers and operating systems, too.

At present, the following ATP versions are available:

- MS-DOS, MS-Windows 3.x/95/98/NT/2000™

• 32-bit, GNU-Mingw32 and Watcom ATP for Windows 95/98/NT/2000/XP/Vista
  
  
• 32-bit, Salford ATP running under MS-DOS, MS-Windows 3.x/95/98
  (This version requires Salford's DOS extender DBOS/486)

- Linux:

• GNU version of ATP

ATP-EMTP is used world-wide for switching and lightning surge analysis, insulation coordination and shaft torsional oscillation studies, protective relay modeling, harmonic and power quality studies, HVDC and FACTS modeling. Typical EMTP studies are:

• Lightning overvoltage studies
• Switching transients and faults
• Statistical and systematic overvoltage studies
• Very fast transients in GIS and groundings
• Machine modeling
• Transient stability, motor startup
• Shaft torsional oscillations
• Transformer and shunt reactor/capacitor switching
• Ferroresonance
• Power electronic applications
• Circuit breaker duty (electric arc), current chopping
• FACTS devices: STATCOM, SVC, UPFC, TCSC modeling
• Harmonic analysis, network resonances
• Protective device testing

W. Scott Meyer was born in Madison, Minnesota, USA, in 1942. He received BS, MSEE, and Ph.D. degrees from the Electrical Engineering Department of the University of Minnesota in 1964, 1966, and 1969, respectively. During 1970 and 1971, he taught as an Assistant Professor at this same location in Minneapolis. Then, after some 9 months working for Systems Control, Inc. (SCI) in Palo Alto, California, Dr. Meyer joined the Bonneville Power Administration (BPA) in Portland, Oregon – an agency of the U.S. government.

Since late 1972, he has been preoccupied with the digital computer simulation of electromagnetic transients. Early milestones along this 29-year evolution include the discovery of machine translation (to make the program run on all computers of common interest) in 1974, and creation of the name EMTP in 1975. In March of 1995, Dr. Meyer formally retired from BPA, and work on ATP at BPA as an unpaid volunteer through early 2004.
(e-mail: )

Tsu-huei Liu was born in the province of Kwei-chou, China, in 1943. Her education in Taiwan ended in 1964 with a Bachelor of Science degree in Physics from National Taiwan University in Taipei. She then moved to the University of Oregon in Eugene, USA, where she studied theoretical physics. After receiving her Ph.D. in 1969, she joined the faculty of Portland State University as an Assistant Professor. This teaching lasted until 1975 when she switched to engineering work at the Bonneville Power Administration (BPA).

Most of the years since 1975 have been absorbed in work on EMTP, although the duties of management have been a distraction during two intervals. First, between 1982 and 1988, Dr. Liu supervised those who were involved with reliability programming, and also EMTP. Second, between 1991 and May 2007, Dr. Liu had served as Manager/Team Lead of the larger Planning Software Support group within System Planning/Network Planning, Manager of IT Quality Control, and Manager of IT Hardware Operations at BPA. Dr. Liu retired from BPA at the end of May, 2007.
(e-mail: )

Several experts around the world have been contributing to EMTP starting in 1975 and later to ATP in close cooperation with Drs. W. Scott Meyer and Tsu-huei Liu.