ABB RELION REX640 Technical Manual page 1423

1MRS759142 C
REX640
Technical Manual
• If AVR lower limit alarm AVR_ALM_LO is TRUE, it resets the voltage
lower command LOWER_U. If AVR high limit alarm AVR_ALM_HI is
TRUE, it resets the voltage raise command RAISE_U.
• If the output MATCH_OK is TRUE, the raise and lower commands are reset.
• If the voltage difference reaches the target value with a hysteresis band that
is in the middle of the tolerance band specified by the settings Voltage Diff
Ov Ex and Voltage Diff Un Ex, the raise and lower commands are reset.
• During matching of network CB synchronization
• If either of the AVR limit alarms AVR_ALM_LO and AVR_ALM_HI is
TRUE, it resets the voltage raise and lower commands.
• When the generator is selected for fine tuning, if the voltage difference is
within the limits of tolerance band specified by the settings Voltage Diff Ov
Ex and Voltage Diff Un Ex, the raise and lower commands are reset.
• When the generator is selected for coarse tuning, if the voltage difference
reaches within the limits of Coarse Volt Diff Ov and Coarse Volt Diff Un,
the raise and lower commands are reset.
Voltage rate of change tuning
When the control command parameter Tune V and F match is set to "Volt match
rate", the function calculates the generator voltage matching rate (dU/dt). The
calculated voltage matching rate is stored to the nonvolatile memory output
VOLT_CHG_RTE and is available in the Monitored data view. Once stored, the value
from the output VOLT_CHG_RTE can be used to set the setting Volt rate of change.
This tuned voltage matching rate proceeds as follows:
1. The generator voltage is adjusted until it lies in the range of 95...97% of the line
voltage, then the adjusting pulse is discontinued.
2. Ten seconds after the first adjusting pulse, the voltage difference ΔU0 is
measured, then a voltage raise command RAISE_U lasting 5 s is given. Ten
seconds after the end of the pulse, the voltage difference ΔU is measured and dU/
dt calculated according to the following formula:
dU U U
0
∆ − ∆
=
dt
5
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3. With this dU/dt value, the generator voltage is brought back to approximately
96%.
Ten seconds later, the generator voltage is brought to approximately 100 % with the
same dU/dt value. After ten seconds, dU/dt is calculated again and shown as
monitored data output VOLT_CHG_RTE.
Frequency matching
Working range of the frequency matcher
Section 9
Control functions
(Equation 327)
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