Figure 10: The absolute value the fault current based the P-coil setting curve)
Looking only the 'absolute value the current' across the faulty section, based the
set coil position produces the curve displayed Figure 10: This representation also fre-
quently referred the curve'.23)
In both equations, positive values stand for 'over compensation' and negative values for
an 'under compensation'. The actual value the fixed coil(s), which and how many
are currently active the grid, usually difficult determine.1 Advantages specifying absolute detuning
The regulator adjusts the reactive current flowing across the faulty section, that always
has the same size.
If detuning specified percentage, the expected reactive current will depend the
size the grid (Ires). even more difficult to
constantly adjust the regulator the cumulative value the fixed coils. The reactive current the same size for both large and small grids.
The quantity reactive current across the faulty section, meaning detuning can calcu-
lated either ‘absolute value’ ‘relative value’. The following equations1
describe
these two types calculation:
Detuning ]
v Ipos Ires A
(1.22)
Detuning %
[ ]
[%] *100
[ ]
Ipos Ires A
v
Ires A
(1.Page Applications
We take care it. Fixed
coils that are installed the same compensation district not have taken into ac-
count. value zero stands for full compensation. And this case, any fixed coils that are installed the grid must be
considered the calculation. This results clear indication the size the expected reactive current across
the faulty section when the regulator has successfully finished the tuning process and an
earth fault occurs.
6.
Under-
compensated
Coil position/A
|IFehler |
/A
Ires
Over-
compensated
.2.3
