Instruction manual
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AQ G3x7 Generator protection IED
132 (211
)
The numerical processes apply the simple R-L model.
For the equivalent impedance elements of the measuring loop, the following differential
equation can be written:
If current and voltage values sampled at two separate sampling points in time are
substituted in this equation, two equations are derived with the two unknown values R and
L, so they can be calculated.
This basic principle is realized in the algorithm by substituting the Fourier fundamental
component values of the line-to-line voltages for u and the difference of the Fourier
fundamental components of two phase currents:
Where
R1 is the positive sequence resistance of the line or cable section between the fault location
and the relay location,
L1 is the positive sequence inductance of the line or cable section between the fault location
and the relay location,
L1, L2, L3 indicate the three phases.
