ABB RELION 630 Series Technical Manual page 218

Section 7
Power management functions
212
Table 262: Load-shedding priority calculation
Load-shedding initiation
Fast load-shedding trigger, slow
load-shedding trigger or
external trigger
Slow load-shedding trigger
Extended load-shedding trigger
Manual load-shedding trigger
(power-based)
Manual load-shedding trigger
(priority-based)
The load-shedding priority due to slow load-shedding trigger is
calculated as the maximum of p1 and p2.
If the load-shedding action is initiated due to multiple load-shedding triggers
simultaneously, the priority order in which the cause of load-shedding is calculated
follows a certain sequence.
• Extended load-shedding (in combination with any other load-shedding triggers)
• Fast load-shedding (in combination with slow load-shedding or manual load-
shedding triggers)
• Slow load-shedding (in combination with manual load-shedding trigger)
• Manual load-shedding
Irrespective of multiple load-shedding trigger conditions, if the load-
shedding priority is calculated corresponding to the overload amount
and slow load-shedding trigger, then the cause of load-shedding is
slow load-shedding.
Similarly, if the load-shedding priority is calculated corresponding to
the manual load-shedding priority and the manual load-shedding
trigger, the cause of load-shedding is manual load-shedding.
In load-shedding blocking condition, the load-shedding in the
subnetwork can be executed via the manual load-shedding trigger.
• LSCACLS calculates the trip information for each load feeder connected to the
busbars in the respective subnetwork based on load-shedding priority. The trip
Shed power calculation
p1
Cumulative shedding power
Power shortfall
p2
Cumulative shedding power
Total overload amount
p3
Cumulative shedding power
load-shedding power of
adjacent PML630
p4
Cumulative shedding power
Manual load-shedding power
Manual load-shedding priority
setting = p5
PML630/Compact Load-Shedding Solution
1MRS757256 F
Load-shedding priority calculation
p1
≥
p2
≥
p3
≥
p4
≥
p5
Technical Manual