Atp Comtrade

8/12/2019 Atp Comtrade

http://slidepdf.com/reader/full/atp-comtrade 1/8

Session 31

Power Systems Protection and Relaying Fall 2012

1/8

Using ATP, ATP Analyzer and MathCAD for Protection Studies

This handout provides instructions for using the ATPDraw model of the Analog Model Power

System to perform protection studies. ATPDraw call the ATP simulation engine, which will beused to perform a fault simulation. You can observe instantaneous currents and voltages usingPlotXY along with and RMS voltages and currents.

The output data from the simulation will be converted to COMTRADE format using ATP

Analyzer. You can also use Analyzer to calculate the sequence components and perform other

calculations is you wish to do so.

Finally, if you have access to MathCAD, you have also received a file that postprocesses the

COMTRADE output and implements some simplified relay models.

The system described in the exam handout has been modeled in ATPDraw. The line parametersentered in the model are based on measurements on the AMPS, so they will differ slightly from

the idealized parameters on the handout. The file is named 525Proj.adp. When you open that project file in ATPDraw you will see the system below.

Avis ta

100%

Z_SRCBUS1

LOAD

BUS4

L3

BUS3BUS2

L1

75% L4

BUS7BUS6

L26 83%L2

F150

The T, N, and A blocks represent the transmission line models of the transient network

analyzer (TNA). The impedance values are set, but you can change them if you wish.

The source impedance can be changed by double-left-clicking your mouse on the Z_SRC

icon. The R and L (really XL) values listed are in Ohms at 60Hz.

The line impedances are changed in the “N” sections of the TNA blocks. You should

probably only change the R and L (again L is XL in Ohms). The capacitance values

aren’t likely to impact your results.The intermediate buses, BUS3 and BUS7, are needed on the physical model power system to

provide fault points. In this model, you don’t need to worry about them.

The switch between BUS1 and BUS2 can be used to connect the top two lines to the source.

If the switch is open, then the lower line and upper line form a radial system with the load at themid-point. If the switch is closed you have two lines in parallel with a second infeed for the fault

current. The switches are open in the base case file included. If you want to do studies with the

switch closed, you should double left click on the switch icon. The following dialog box will



Session 31


2/8

open. Replace the “1” in each of the T-cl entries with a “-1”. This will force the simulation to

treat the breakers as closed.

The fault blocks are located at points where you can implement faults. One is at about 75%

of the length of the lower line, another is at 83%, another at 100% (at BUS4) and one at 150%(at BUS3). You can move these to other places in the system. The system as sent does not have

any faults enabled. To set a fault, you need to double left click the fault block icon for the fault

location you want to use. You will see the following dialog box. The numbers in the “VALUE”column are the ones you need to change to create a fault. The help menu for the dialog box will

provide an overview of all of the parameters.

The parameters that you will need to change to implement a fault are the “Nxx_GO” values.For example, to do a SLG fault on phase A occuring 50 milliseconds (3 cycles) into the

simulation, you should change NA_GO to 0.05. If you want to implement a LL fault between

phases B and C occuring 50 milliseconds into the simulation, you should change BC_GO to0.05. To do a DLG fault from B to C to ground you need to set NB_GO and NC_GO to both

turn on. Make sure your turn off any previous faults before you create a new one (set the start

time back to a large number (but smaller than the stop time (xx_STP).

I suggest leaving Nx_STP set to beyond the end of the simulation (i.e. the fault will stay onthe system). This will make analysis a little easier. The simulation is presently set to run for a

total of 200 milliseconds which should be sufficient for most cases.

If you are familiar with ATP, you can replace with with time controlled switches if you are

prefer to use them.





Session 31


4/8

After your simulation is complete, you can view your results with the plotting program that I

sent along called PlotXY. The archive I sent you should have it set up so it appears in the “ATP”

pulldown menu as well. The menu in the figure above has additional options since I have someother programs on my computer. When the program opens you will see:



Session 31


5/8

To select a variable for plotting simply left click the mouse on that name and it will appear in

the list on the right. If you select the “Plot” button the a new window with the waveforms willshow up.

If you prefer to do you analysis of these cases with PlotXY and only look at the

instantaneous overcurrent elements that will be sufficient for at least partial extra credit.

ATP Analyzer was developed by BPA to make it easier for protection engineers to use ATP

simulations (the development of ATPDraw was also supported by BPA for the same reason).

When you open ATP Analyzer you will get an empty window. Choose File New – MainCase Atp.pl4 Import as shown below.

Browse to find the file you wish to open (if you didn’t give any specific directory location forthe “Make File As” command in ATPDraw, this will be in the “ATPDraw4/atp/” directory.

When you select the file a set of plots will show up on your screen. These are the first entries

of the PL4 file. Select “Done” to close this window.

When you close the window you will see two windows inside the ATPAnalyzer window.Delete the signals in the “Main Case Signal Selections” in the Analog signals list (select one at a

time or as a group and then choose “Cut” from the Edit Selections pull down menu or press the

delete key on your keyboard). Then replace them with the ones shown in the figure below. If you



Session 31


6/8

plan to use the enclosed MathCAD file, these need to be in the order shown or you will need to

edit the MathCAD file. Entries are selected from the list on the right side by right or left clickingon the desired entry.

If all you want to do is create a COMTRADE file, then the next step is to resample the ATP

output file to a more typical rate for a microprocessor relay. Choose “Main Case” “Resample” “Linear Interpolation, All Signals” (either type of interpolation is sufficient for the moment).

Then a dialog box will open. The text box at the bottom of the screen shows the present

sampling rate, replace this with 960 (this is 16 samples per 60 Hz cycle). This is a fairly common

sampling rate and the MathCAD file is set up for this.When you click ok a new window will open asking if you want to Low Pass Filter the Data.

Check the box to perform the filtering. The window will freeze for a few moments as the filter

parameters are calculated and the button “Resample” will become active. Select that button.



Session 31


7/8

Then you can save the COMTRADE file with the following “File” “Save Selected MainCase Analog Signals As” “Comtrade File” “ASCII Data (C37.111-1999)”. Use the 1999

ASCII format for the COMTRADE to work with the MathCAD file.

The version of PlotXY sent on your CD will also plot waveforms from COMTRADE files.



Documents

Atp Comtrade