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4.6.4 Synchronization check
The user should set On for scheme switch [SYNC01-SYNCHK1EN] when synchronization check
is required.
(i) Synchronization conditions
The synchronizing relays are used to check the respective conditions of the incoming-line and
the running-line. For example, the ∆V, ∆θ, and ∆f variances of Vi and Vr may be examined
when the SYNCHK function is used in a synchronous network. Conversely, the ∆θ reducing-
degree feature can be applied for asynchronous networks; the SYNCHK function can use
signals ‘∆θ1≈0’ and ‘∆θ1_less’ in order to decide whether the difference-angle is reducing. Thus,
the SYNCHK function is required to have two sets of check logic covering both (1) synchronous
conditions and (2) asynchronous conditions.
ΔƟ1: Phase-variance of Running and Incoming
ΔV1: Voltage-variance of Running and Incoming
Δf1: Frequency-variance of Running and Incoming
ΔƟ1≈0: Phase-variance being near zero between Running and Incoming
ΔƟ1 less: Reducing in phase-valiance
To check for Synchronous network
To check for Asynchronous network
Figure 4.6-12 Synchronization check relays in SYNCHK_Ry1
ΔƟ2: Phase-variance of Running and Incoming
ΔV2: Voltage-variance of Running and Incoming
Δf2: Frequency-variance of Running and Incoming
ΔƟ2≈0: Phase-variance being near zero between Running and Incoming
ΔƟ2 less: Reducing in phase-valiance
To check for Synchronous network
To check for Asynchronous network
Figure 4.6-13 Synchronization check relays in SYNCHK_Ry2
Figure 4.6-14 shows the synchronization check logic in the SYNCHK1 function. The user
should note that the logic has been separated for (1) the synchronous condition and (2) the
asynchronous condition; the synchronization check logic is initiated when the
“DPSY01_OEC_RCV” signal is received, which is identical to an operate-command in the On-
direction.
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