Hitachi Relion 670 Series Applications Manual page 207

1MRK506375-UEN Rev. N
Section 12
12.1 Synchrocheck, energizing check, and synchronizing
SESRSYN
12.1.1 Identification
Function description
Synchrocheck, energizing check, and
synchronizing
12.1.2 Application
12.1.2.1 Synchronizing
To allow closing of breakers between asynchronous networks, a synchronizing feature is provided.
The breaker close command is issued at the optimum time when conditions across the breaker are
satisfied in order to avoid stress on the network and its components.
The systems are defined as asynchronous when the frequency difference between bus and line is
larger than an adjustable parameter. If the frequency difference is less than this threshold value the
system is defined to have a parallel circuit and the synchrocheck function is used.
The synchronizing function measures the difference between the U-Line and the U-Bus. It operates
and enables a closing command to the circuit breaker when the calculated closing angle is equal to
the measured phase angle and the following conditions are simultaneously fulfilled:
• The voltages U-Line and U-Bus are higher than the set values for UHighBusSynch and
UHighLineSynch of the respective base voltages GblBaseSelBus and GblBaseSelLine.
• The difference in the voltage is smaller than the set value of UDiffSynch.
• The difference in frequency is less than the set value of FreqDiffMax and larger than the set
value of FreqDiffMin. If the frequency is less than FreqDiffMin the synchrocheck is used and the
value of FreqDiffMin must thus be identical to the value FreqDiffM resp FreqDiffA for
synchrocheck function. The bus and line frequencies must also be within a range of ±10% from
the rated frequency. When the synchronizing option is included also for autoreclose there is no
reason to have different frequency setting for the manual and automatic reclosing and the
frequency difference values for synchronism check should be kept low.
• The frequency rate of change is less than set value for both U-Bus and U-Line.
• The difference in the phase angle is smaller than the set value of CloseAngleMax.
• The closing angle is decided by the calculation of slip frequency and required pre-closing time.
The synchronizing function compensates for the measured slip frequency as well as the circuit
breaker closing delay. The phase angle advance is calculated continuously. The calculation of the
operation pulse sent in advance is using the measured SlipFrequency and the set tBreaker time. To
prevent incorrect closing pulses, a maximum closing angle between bus and line is set with
CloseAngleMax. To minimize the moment stress when synchronizing near a power station, a
narrower limit for the CloseAngleMax needs to be used.
The reference voltage can be phase-neutral L1, L2 or positive sequence. By setting the phases used
for SESRSYN, with the settings SelPhaseBus and SelPhaseLine, a compensation has to be made
Railway application RER670
Application manual
Control
IEC 61850
identification
SESRSYN
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IEC 60617 ANSI/IEEE C37.2
identification device number
25
sc/vc
SYMBOL-M V1 EN-US
Section 12
Control
IP14558-1 v4
M14889-1 v4
IP15111-1 v1
SEMOD171992-5 v11
201