ABB RELION REX640 - Page 1577

Figure 867: Frequency matching pulses generation with variable command pulse
length
Frequency matching with variable command pulse off intervals
When the setting Frequency match mode is set to "Variable Interval", the frequency
matching is done with variable command pulse off intervals.
The voltage match command pulses are now the same length, but the intervals are
inversely proportional to the frequency slip.
Pulse length (tpf): adjustable with the setting Freq pulse Min Dur (tpfmin)
Pulse off interval (tsf): calculated as
tsf
f f f s
Gen Bus Gen
=
−
= ≤
1 1
30 [Sec]
(Equation 364)
s Measured frequency slip across the CB to be synchronized
f
Gen
Measured generator side frequency
f
Bus
Measured bus side frequency
Reset of frequency raise and lower command pulses
The generated frequency raise and lower command pulses RAISE_F and LOWER_F
are immediately reset if any of the following conditions is met.
• During matching of its own CB synchronization
- If governor lower limit alarm GOV_ALM_LO is TRUE, it resets the frequency
lower command LOWER_F. If governor high limit alarm GOV_ALM_HI is TRUE, it
resets the frequency raise command RAISE_F.
- If the output MATCH_OK is TRUE, the raise and lower commands are reset.
1MRS759142 F
Control functions
REX640
Technical Manual
1577