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Dead line or bus value
Live line or bus value
Difference angle
U_Bus
U_Line
Difference voltage
f
U_Bus
f
U_Line
Frequency[Hz]
f
= abs(
f
U_Bus
-
f
U_Line
)
Rated frequency
Frequency deviation
=
U_Bus
-
U_Line
Difference frequency
Figure 315: Conditions to be fulfilled when detecting synchronism between systems
When the frequency, phase angle and voltage conditions are fulfilled, the duration
of the synchronism conditions is checked so as 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
from the moment the closing signal is given until the circuit breaker finally closes
is about 50...250 ms. The selected
Closing time of CB informs the function how
long the conditions have to persist. The Synchro check function compensates for
the measured slip frequency and the circuit breaker closing delay. The phase angle
advance is calculated continuously with the formula.
Closing angle
= ∠
− ∠
(
)
° +
−
(
)
×
+
(
)
×
°
(
)
U
U
f
f
T
T
Bus
Line
Bus
line
CB
PL
360
(Equation 74)
∠ U
Bus
Measured bus voltage phase angle
∠U
Line
Measured line voltage phase angle
f
Bus
Measured bus frequency
f
line
Measured line frequency
T
CB
Total circuit breaker closing delay, including the delay of the protection relay
output contacts defined with the
Closing time of CB
setting parameter value
The closing angle is the estimated angle difference after the breaker closing delay.
The
Minimum Syn time setting time can be set, if required, to demand the minimum
time within which conditions must be simultaneously fulfilled before the
SYNC_OK
output is activated.
The measured voltage, frequency and phase angle difference values between
the two sides of the circuit breaker are available as monitored data values
U_DIFF_MEAS, FR_DIFF_MEAS and PH_DIFF_MEAS. Also, the indications of the
conditions that are not fulfilled and thus preventing the breaker closing
permission are available as monitored data values U_DIFF_SYNC, PH_DIF_SYNC
and FR_DIFF_SYNC. These monitored data values are updated only when the
Synchro check is enabled with the
Synchro check mode setting and the measured
ENERG_STATE is "Both Live".
Continuous mode
The continuous mode is activated by setting the parameter
Control mode to
"Continuous". In the continuous control mode, Synchro check is continuously
Control functions
1MRS758755 C
646
REC615 & RER615
Technical Manual