Schweitzer Engineering Laboratories SEL-700G Series, Инструкция по эксплуатации

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H.17
Date Code 20170814 Instruction Manual SEL-700G Relay
Synchrophasors
C37.118 Synchrophasor Protocol
Table H.12 lists the data settings available on any SEL-700G serial port
(setting SPEED), and the maximum message size that can fit within the port
bandwidth. Blank entries indicate bandwidths of less than 20 bytes.
Referring to Table H.11 and Table H.12, it is clear that the lower SPEED
settings are very restrictive.
The smallest practical synchrophasor message would be comprised of one
digital status word, and this message would consume 24 bytes (includes
frequency and DFDT). This type of message could be sent at any message rate
(MRATE = 60) when SPEED := 38400, as much as MRATE := 5 when
SPEED := 2400, and as much as MRATE := 1 when SPEED := 600.
Another example application has messages comprised of nine synchrophasors,
one digital status word, and two analog values. This type of message would
consume 68 bytes. The 68-byte message could be sent at any message rate less
than or equal to ten (MRATE) when SPEED := 9600.
Protocol Operation
The SEL-700G only transmits synchrophasor messages over serial ports that
have setting PROTO := PMU. The connected device is typically a
synchrophasor processor, such as the SEL-3306. The synchrophasor processor
Table H.11 Size of a C37.118 Synchrophasor Message
Item
Possible Number
of Quantities
Bytes
per
Quantity
Number of Bytes
Minimum Maximum
Fixed
18 18
Synchrophasors 0–18
4 0 72
Frequency/DFDT 2 (fixed)
2 4 4
Analog Values 0–4
4 0 16
Digital Status Words 0–1
2 0 2
Total (Minimum and Maximum) 22 112
Table H.12 Serial Port Bandwidth for Synchrophasors (in Bytes)
Global Setting
MRATE
Port Setting SPEED
300 600 1200 2400 4800 9600 19200 38400 57600
1 21 42 85 170 340 680 1360 2720 4080
2 21 42 85 170 340 680 1360 2040
4 (60 Hz only) 21 42 85 170 340 680 1020
5 34 68 136 272 544 816
10 34 68 136 272 408
12 (60 Hz only) 28 56 113 226 340
15 (60 Hz only) 21 45 90 181 272
20 (60 Hz only) 34 68 136 204
25 (50 Hz only) 27 54 108 163
30 (60 Hz only) 22 45 90 136
50 (50 Hz only) 27 54 81
60 (60 Hz only) 22 45 68