28 Program features
Flat-top limit
Normally, the inverter has a power capability shaped like a semi-circle meaning that the
inverter can produce as much active power as it can produce reactive power. Enabling the
Flat-top limit in the inverter changes the shape of the power capacity to a semi-circle
shape with a flat top instead of the normal curved form.
The Flat-top limit applies a new setpoint to the full active power capacity of the inverter. As
the Flat-top setpoint is lower than the setpoint for nominal active power and AC current
limit is unaffected by Flat-top, it increases the full active power range of the inverter i.e. to
the full width of the flat top. Note that Flat-top works just like a constant active power limit.
Settings
130.90 Flat-top limit
Power gradient
The power gradient function limits the rate of rise in active power to a predefined value.
This has the effect of stabilizing the grid as the power cannot change too rapidly. The
power gradient function can be enabled with parameter 130.92 Active power ramping and
the rate of rise is set with parameter 130.93 Active power ramp.
A shut down ramp is implemented to achieve smooth shut down when a stop command is
received. Power is first reduced slowly to zero before the grid relays are opened. The ramp
is defined in parameter 130.94 Shut down ramp. The shut down ramp is not applied when
the grid disconnection takes place because of faults or grid disturbances.
P
t
130.93 Active power ramp
P
t
130.94 Shut down ramp
Stop command Actual stop
To Next Page
