MATLAB: How to tune the Block Parameters of the Surge Arrester Block to match a manufacturer datasheet

arrestermodellingSimscape Electricalsurge

How can I tune the Block Parameters of the Surge Arrester Block to match a manufacturer datasheet?

Best Answer

As specified in the documentation page below of the "Surge Arrester" block, the default parameters "k" and "alpha" fit the average V-I characteristic provided by most manufacturers. The only parameter that you need to change is the protection voltage "Vref" specified at a particular reference current "Iref" (usually 500 A).
https://www.mathworks.com/help/physmod/sps/powersys/ref/surgearrester.html
The "Protection Voltage" parameter would be defined based on the reference current that is used for the column.
For example - in the 8.4MCOV Surge Arrester highlighted in the below image, the protection voltage will be defined as 19.8kV for a reference current of 500 amperes. 
The attached script "MOV_plot.m" plots the V-I characteristics of the arrester.  This script uses the function "sps_PlotVIcharSurgeArrester.m", also attached.
The included script uses the 8.4 kV MCOV arrester provided in the above image as an example.
The V-I characteristics show the 3 segments and reference voltage in "pu" (V_arrester/Vref):
  • segment 1 in blue
  • segment 2 in red
  • segment 3 in yellow
The first case uses  "Vref" = 19.8 kV, "Iref" = 500 A with the default "k" and "alpha" values and for 0-10 kA range values (see the "1st set of parameters" section in the script). In the below figure, the red circles correspond to 8/20 us discharge voltage specified in the datasheet.
Fitting is not perfect, but it should be mentioned that the protection voltage at a particular current also depends on current pulse duration (i.e lightning pulse 1.2/50 us ,  8/20 us,…  or  temporary overvoltage).
The second case is obtained by using "Vref" = 21.1 kV, "Iref" = 1.5 kA and modified "alpha" values (see the '"2nd set of parameters" section in the script). Fitting is enhanced:
Using this provided script and function, you can tune the "k" and "alpha" parameters in order to better fit the actual V-I characteristics.
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