Load-Shedding Blocking - ABB RELION 630 Series Technical Manual

Section 7
Power management functions
7.2.4
208
PML630 performs load-shedding action in its own area, provided that an adjacent
PML630 has executed the load-shedding action and the actual shed load is less than
required. PML630 receives the load-shedding information from an adjacent PML630
to shed identified loads in its own area.
The load-shedding trigger is extended by an adjacent PML630,
provided that a load-shedding action is initiated in the respective
adjacent PML630 due to fast load-shedding trigger, external trigger
input or load-shedding trigger received from another adjacent
PML630.
See NPMMXU, LSCACLS and PPLSGGIO for details regarding
extended load-shedding action.

Load-shedding blocking

Load-shedding is blocked due to various conditions of power source, bus coupler or
tie circuit breaker.
Load-shedding blocking is calculated as shown in
Table 261: Conditions for load-shedding blocking calculation
Load-shedding blocking due to power source
• Circuit breaker position is in intermediate for
more than set value of circuit breaker
intermediate setting.
• Circuit breaker position is invalid.
• IED data quality is bad.
Depending on the network circuit breaker configuration as bus
coupler/tie circuit breaker, the load-shedding blocking is calculated
for the network circuit breaker.
Load-shedding is also blocked if the power source for an external connection is not
configured correctly.
If the load-shedding blocking is activated due to the power source, load-shedding is
blocked in the respective subnetwork where the power source is connected.
If the load-shedding blocking is activated due to the network circuit breaker, load-
shedding is blocked in the associated subnetworks of a network circuit breaker.
If two subnetworks are formed due to the open status of the
compensated circuit breaker status of the network circuit breaker and
load-shedding blocking is activated from the respective network
Table 261.
Load-shedding blocking due to bus coupler/tie
circuit breaker
• Circuit breaker position is in intermediate for
more than set value of circuit breaker
intermediate setting.
• Circuit breaker position is invalid.
• IED data quality is bad.
PML630/Compact Load-Shedding Solution
1MRS757256 F
Technical Manual