Manual Load-Shedding Trigger; Extended Load-Shedding Trigger - ABB RELION 630 Series Technical Manual

1MRS757256 F
7.2.3.3
7.2.3.4
PML630/Compact Load-Shedding Solution
Technical Manual
• Phase overcurrent detection module has operated.
• Calculated average demand is violated.
• External input is configured and the input gets activated, for example transformer
or feeder overcurrent IED (RET/REF630) start signals.
If the power flow of the power source is away (that is, power flow
direction is negative) from the busbar, slow load-shedding trigger
from the respective power source is not initiated.
The slow load-shedding trigger due to external input is active if the
phase overcurrent detection module is enabled.
See PSCSWI and NPMMXU for details regarding slow load-
shedding trigger calculation.
When phase overcurrent is detected, it is expected that the actual current of power
source comes down when the load feeders are tripped. If the current does not fall
below the threshold value, PML630 retriggers the slow load-shedding action until the
current is reduced. This retriggering of the slow load-shedding trigger due to phase
overcurrent can be handled by a set interval time. The delay in updating the currents
in the phase overcurrent detection module of the power source after the load feeder has
tripped can also be handled by retriggering after the set interval time.
The slow load-shedding trigger for the individual power source is disabled by external
inputs in respective PSCSWI.
The slow load-shedding trigger is inhibited (that is, blocked) for all the power sources
by an external input in NPMMXU.

Manual load-shedding trigger

The manual load-shedding trigger is initiated in each subnetwork by the system
operator irrespective of a power shortfall.
Manual load-shedding can be executed either based on priority or power (that is,
amount of load to be shed). If configured, it is also possible to execute the manual
load-shedding action initiated by an external input. If an external system (such as
COM600) sends information for load-shedding (priority or by power) along with an
external trigger, load-shedding can be activated for the subnetwork.
See LSCACLS for load-shedding action due to manual load-shedding
trigger.

Extended load-shedding trigger

In cPMS load-shedding configuration B, extended load-shedding trigger is initiated
from adjacent PML630s during contingency in the extended electrical network area.
Power management functions
Section 7
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