symbolic dynamic models for highly varying power system loads

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2. Constant number of cells: The data set can be divided into N number of cells keeping
cell width as a variable. Cell width depends on the maximum and minimum value of
current in the data set, thus
?x = (I max -I min )/N
4.3 Test conditions
The real data, obtained directly from an EAF, have been measured with a
sampling frequency of 10 kHz. Therefore the number of measured data points in a cycle
can be obtained as follows:
supply frequency = 60 Hz
one cycle = 1/60 second
1/ 60
number of data points in one cycle =
4
1/10
= 500/3 = 166.7.
or 500 data points = 3 cycles.
To form a Symbolic Dynamic dictionary and to predict future values, the real data
is discretized as described above. To do so, the data set is shifted and scaled. In other
words if X is the data set under consideration then transformed data set Y is obtained as
Y=fix (aX+b),
where fix is Matlab function for rounding off, a and b are constants. The values of the
constants a and b depend on the maximum and minimum values in the data set and how
cell division is done to transform the data.