ABB REG670 Applications Manual page 589

1MRK 502 071-UEN -
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual
follower method with the follow tap option, the master is executing the second, third,
etc. commands with time delay t2. The followers on the other hand read the master's
tap position, and adapt to that with the additional time delay given by the setting
tAutoMSF and set individually for each follower.
tMin: The minimum operate time when inverse time characteristic is used (see section
"Time characteristic", figure 283).
Line voltage drop compensation (LDC)
OpertionLDC: Sets the line voltage drop compensation function On/Off.
OperCapaLDC: This setting, if set On, will permit the load point voltage to be greater
than the busbar voltage when line voltage drop compensation is used. That situation
can be caused by a capacitive load. When the line voltage drop compensation function
is used for parallel control with the reverse reactance method, then OperCapaLDC
must always be set On.
Rline and Xline: For line voltage drop compensation, these settings give the line
resistance and reactance from the station busbar to the load point. The settings for
Rline and Xline are given in primary system ohms. If more than one line is connected
to the LV busbar, equivalent Rline and Xline values should be calculated and given as
settings.
When the line voltage drop compensation function is used for parallel control with the
reverse reactance method, then the compensated voltage which is designated "load
point voltage" U is effectively an increase in voltage up into the transformer. To
L
achieve this voltage increase, Xline must be negative. The sensitivity of the parallel
voltage regulation is given by the magnitude of Rline and Xline settings, with Rline
being important in order to get a correct control of the busbar voltage. This can be
realized in the following way. Figure
controlled in a parallel group with the reverse reactance method and with no
circulation (for example, assume two equal transformers on the same tap position).
The load current lags the busbar voltage U
of the impedance Rline and Xline is designated j1.
284 shows the vector diagram for a transformer
with the power factor j and the argument
B
Section 15
Control
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