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 circuit breaker and the closing system, the delay
between the closing signal and the circuit breaker 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 circuit breaker closing delay and output
type dependent delay. The synchro check function compensates for the measured
slip frequency and the circuit breaker closing delay. The closing angle advance is
calculated continuously:
Closing angle = ∠ − ∠
( )
° + −
( )
⋅
⋅U U f f
TCB
Gen Bus Gen Bus
1000
3600°
(Equation 356)
∠ U
Bus
Measured generator voltage phase angle
∠ U
Gen
Measured bus voltage phase angle
TCB Parameter
Closing time of CB
to be set as in
Equation 357
(Equation 357)
t
CB
Circuit breaker closing delay in ms
T
PL
Output type dependent delay in ms (see
Table 1517
)
x Hardware delays between the protection relay and CB in ms; delays due to, for
example, auxiliary relays and contactors, if used
Table 1517: Typical delays for different output types
Output type Recommended value for T
PL
Generator voltage
measurement: Non-Adaptive
Bus voltage measurement:
Non-Adaptive
Generator voltage
measurement: Adaptive
Bus voltage measurement:
Non-Adaptive
Semiconductor output (SPO) 16 ms 7 ms
Mechanical relay output
(POSP, PODP)
23 ms 13 ms
The
Minimum Syn time
setting defines the minimum time for which synchro check
conditions must be simultaneously fulfilled.
ASGCSYN can be set to the bypass mode by setting the parameters
Synchrocheck mode
and
Live dead mode
to "Off" or, alternatively, by
activating the BYPASS input. In the bypass mode, the synchro check
conditions are always fulfilled. Otherwise, the operation is similar to the
normal mode.
The frequency slip acceleration (ds/dt) FR_SLIP_ACCL is the average value of
frequency slip difference (Δs) calculated over a time period of 0.5 s.
1MRS759142 F
Control functions
REX640
Technical Manual
1563
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