Modelling
How to
Compatibility
Can
you do shortcircuit calculations with Microtran?
Yes. Short circuit calculations are relatively straightforward using Microtran. If only symmetrical currents are desired, they can be obtained directly from the steady-state solution. To obtain "asymmetric" currents, run a transient simulation and set the closing time of the switch that simulates the fault to close at a voltage zero crossing. The correct dc offset will represented correctly according to the characteristics of the network.
Yes. You can simulate system harmonics by modelling nonlinearities, and letting the transient simulation run until steady state is reached. Harmonic decomposition and analysis tools are built into mtPlot, or can be carried out with the stand-alone support program "harmonic". Another common method to simulate hamonics for power quality studies is to inject harmonic current sources at various frequencies, and examine the behaviour of the network after steady-state is reached.
Can
you do Loadflow and transient stability studies?
Microtran is not the best tool for transient stability simulations. Although fairly sophisticated machine models are available, Microtran was not designed to run simulations in the time frames used in stability studies. Of course, some users have tried with varying degrees of success.
Loadflow calculations cannot be done with Microtran, because there is no provision to enter data in the traditional loadflow way.
In Microtran a transformer is usually modelled with the aid of mtdata, which takes the nameplate and test sheet data of a transformer and converts it into a coupled inductance matrix that correctly reproduces open and short circuit tests at power frequency, for three phase units as well as single-phase banks. This basic type of modelling produces reasonable answers from dc to 5 kHz or so. The asymptotic behaviour of the transformer at higher frequencies can be modelled by placing capacitances at the terminals and between windings.
To model saturation and hysteresis, nonlinear branches are added externally to the basic power frequency model. Any number of windings can be modelled, and phase shift is automatically taken into account through proper winding connection.
An ideal transformer model does exist, but it is used primarily to provide galvanic isolation (e.g., voltage sources not connected to ground).
Plot
a variable against another
Using mtPlot, go to "curve math" and select "curve 1 vs curve 2" from the drop list.
Include
a plot into a document
In the preint menu of mtplot, select either the clipboard or a file using the radio buttons for output device.
The clipboard option will place a bmp file in the Windows clipboard which you can include into a document using the "paste" command.
The file option lets you save the plotted curve in a number of graphic file formats such as jpg, emf, wmf, and bmp.
Mtplot uses a graphic engine that provides a large amount of flexibility to add headers, footers, tags, legends, etc. This can be accessed by right-clicking on the plot surface and modifying the 2D chart control directly. To add drawing elements such as arrows, lines, shapes, etc., the best option is to save the plot to a file and to modify this file with an image editore (e.g., paint)
Compatibility
Not directly. Although Microtran was developed from the original code that eventually became the EMTP and other incarnations of the EMTP, small changes in the input format make translation a tedious task.
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