Landis & Staefa Division
CC1B7865E
February 10, 2000
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9. Self-setting function
)
«
tunE»
is only possible in high-fire operation, in the «modulating burner» mode.
The self-setting function «
tunE»
is a pure software function unit that is integrated into
the controller. In the «modulating» mode of operation, «
tunE»
tests the response of the
controlled system to steps of the positioning signal according to a special procedure. A
complex control algorithm uses the response of the controlled system (actual value) to
calculate and store the control parameters for a PID or PI controller (set dt = 0!). The
«
tunE»
procedure can be repeated as often as required.
Self-setting
Start
Identification of
the controlled
system
PID controller
settings
Controller
Controlled
system
Y
W
X
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The «
tunE»
function uses two different methods that are automatically selected
depending on the dynamic state of the actual value and the difference from the setpoint
at the start. «
tunE»
can be started from within any dynamic actual value sequence.
If there is a
large difference between actual value and setpoint
when «
tunE»
is
activated, a switching line is established around which the controlled variable performs
forced oscillations during the self-setting procedure. The switching line is set at such a
level that the actual value should not exceed the setpoint.
Switching
level
w
x
Start
t
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With a
small deviation
between setpoint and actual value, for instance when the
controlled system has stabilized, a forced oscillation is performed around the setpoint.
9.1 Self-setting function in high-fire operation
Two procedures
