Dead bus voltage
Live bus voltage
UBusA
UBusB
f
BusA
f
BusB
Frequency[Hz]
∆f = f
BusA
- f
BusB
Rated frequency
Diff frequency
Diff angle
∆φ =∠U
BusA
- ∠U
BusB
ΔU = |U
BusA
| – |U
BusB
|
Diff voltage
Diff angle
Figure 872: Conditions to be fulfilled when detecting synchronism between systems
When the measured difference of voltages (U_DIFF_MEAS) and measured difference
in frequency (FR_DIFF_MEAS) are within the synchro check limits given in
Table
1530
, the output MATCH_OK is activated. The output MATCH_INPRO is activated when
the voltage and frequency matching is in progress. The matching status input is
received via ASC1_NS_DAT signal from ASCGAPC.
When the frequency, phase angle and voltage conditions are fulfilled, the duration
of the synchronism conditions is checked to ensure that they are still met when
the condition is determined on the basis of the measured frequency and phase
difference. Depending on the CB and the closing system, the delay between the
closing signal and the CB closing is about 50...250 ms. The selected
Closing time of
CB
informs the function how long the conditions have to persist. The value covers
both the CB closing delay and the output type dependent delay. The synchro check
function compensates for the measured slip frequency and the CB closing delay.
The closing angle advance is calculated continuously:
Closing angle = ∠ − ∠
( )
° + −
( )
⋅
U U f f
TCB
BusA BusB BusA BusB
1000
⋅ °
360
(Equation 369)
∠ U
BusA
Measured bus A voltage phase angle
∠ U
BusB
Measured bus B voltage phase angle
TCB Parameter
Closing time of CB
to be set as in
Equation 370
(Equation 370)
t
CB
CB closing delay in ms
T
PL
Output type dependent delay in ms (see
Table 1531
)
x Hardware delays between the protection relay and CB in ms; delays due to, for
example, auxiliary relays and contactors, if used
1MRS759142 F Control functions
REX640
Technical Manual
1593
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