4.173
Date Code 20170814
Instruction Manual
SEL-700G Relay
Protection and Logic Functions
Group Settings (SET Command)
Autosynchronism
The autosynchronizer is used to match the frequency, phase, and voltage of an
incoming generator to the frequency, phase, and voltage of the bus before
allowing the generator breaker to be closed. The SEL-700G Relay offers built-
in autosynchronism. See Figure 4.115 for an overall block diagram. The relay
uses system and compensated generator phase voltages (VS and Vpxc,
respectively) and provides an autosynchronism function that:
➤
Controls generator frequency so that the slip frequency
difference between VS and Vpxc is within an acceptable
frequency window.
➤
Controls generator frequency so that the compensated angle
difference between Vpxc and VS is within an acceptable
window.
➤
Controls generator voltage, Vpxc, so that Vpxc is within an
acceptable magnitude window.
Figure 4.115
Overall Functional Block Diagram
The autosynchronism feature works in conjunction with the X-side
synchronism-check function. You must first enable 25X elements (see
Table 4.47 for detail) and then set EAUTO := DIG to enable the
autosynchronism elements. Figure 4.115 shows the Relay Word bits (and
other information) from synchronism check that are also used by the
autosynchronism elements.
q
w
See Table 4.47
e
See Figure 4.130, Figure 4.131
and
r
See Figure 2.24
Synchronism-Checking Function
Settings
Analog:
Vpxc, Compensated generator phase voltage
Relay Word bits:
BSYNCHX, Block synchronism check
59VSX, System/Bus voltage within acceptable window
59VPX, Generator voltage within acceptable window
VDIFX, Magnitude difference (|VS| - |Vpxc|) acceptable
GENVLO, Generator voltage < system voltage
GENVHI, Generator voltage > system voltage
SFX, Slip frequency acceptable
25C, Initiate breaker close
Measurements
VPX
Generator phase voltages
VS
System / Bus voltage
FREQX Generator
frequency
FREQS System / Bus frequency
To Governor
(Speed Control)
To Exciter
(Voltage Control)
Autosynchronism Elements
Raise Frequency
Lower Frequency
Raise Voltage
Lower Voltage
1
CLOSE Logic 3
2
4
Summary of Contents for SEL-700G Series
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