Basler Electric DGC-2020 - Manual (Page 586)

K
i
- Integral Gain
Set the initial value of K
i
to be a tenth of the value set for K
p
. Start the generator and close the breaker to
the dead bus.
Next, modify the Speed Trim set point to a level that is one or two hertz higher than the initial setting.
Verify that the generator’s output frequency approaches the new value in a stable manner. Set the Speed
Trim set point back to its original value and observe the generator’s output frequency. Next, modify the
Speed Trim set point to a level that is one or two hertz lower than the initial setting observe the generator
output frequency. Finally, set the Speed Trim set point back to its initial value, and observe the generator
output frequency to verify it operates in a stable manner. If stable operation is not achievable it may be
necessary to lower the value for K
i
. Repeat this procedure, raising K
i
until the system is unstable, and
then lower it to the highest value that achieved stable operation.
K
d
- Derivative Gain
If the performance with K
p
and K
i
alone is satisfactory, it is recommended you leave K
d
at a value of zero.
K
d
can amplify noise in a system so it should be used with great care. Otherwise K
d
, the derivative
controller gain, can be used in conjunction with T
d
, the noise filter constant, to reduce overshoot obtained
with P
i
control. Setting K
d
and Td is an iterative process which can be accomplished by performing the
following steps.
Set an initial value of K
d
that is 1/10 th the value of K
p
or 1/10 th the value of K
i
, whichever is smaller.
Modify the Speed Trim set point to a level that is one or two hertz higher than the initial setting. Verify that
the generator’s output approaches the new value in a stable manner. Set the Speed Trim set point back
to its original value and observe the generator’s output frequency. Next, modify the Speed Trim set point
to a level that is one or two hertz lower than the initial setting observe the generator output frequency.
Finally, set the Speed Trim set point back to its initial value, and observe the generator output frequency
to verify it operates in a stable manner. Repeat with higher values of K
d
until the system begins to be
unstable, and then enter half this value as the K
d
gain.
If high frequency noise seems to be entering the system, T
d
is the constant of the low pass filter which
filters the controller input to reduce the effects of such interference when derivative control is employed.
T
d
ranges from 0 to 1 with an increment of 0.001. T
d
=0 is no filtering, T
d
=1 is heaviest filtering. If T
d
adjustment is necessary, set T
d
to 0.001 and see if the noise induced behavior is reduced. Raise T
d
until
desired reduction of noise behavior is achieved. Once T
d
has been set, tune K
d
again. If noise again
appears to be a problem, adjust T
d
until desired behavior is achieved, then retune K
d
.
var/PF Controller Tuning Procedure
Once desired voltage controller performance is obtained, the var/PF controller can be tuned. Two tuning
methods are presented, one where the machine is paralleled to the utility to tune systems that are used
for utility parallel operation and a second method where machines are paralleled together to tune systems
employing island parallel operation.
var/PF Controller Tuning Procedure Using Parallel to Mains Operation
In Parallel to Mains operation the var/PF controller regulates the kvar output of the machine at a level
specified by the kvar Setpoint % setting when the control mode is kvar control, or it regulates the kvar
output to maintain the power factor specified by the PF Setpoint setting when the control mode is set to
PF control.
Set the K
p
, K
i
, and K
d
gains in the var/PF controller to 0. Set the K
g
value to 0.1. Enable the var/PF
controller, and set the control mode to Var Control. The generator must be paralleled to the utility (as
indicated by the Parallel to Mains element in logic) in any of the tuning steps where the system is being
tested for stable operation.
K
p
- Proportional Gain
Set an initial value of K
p
= 1 in the var/PF Controller. Enable the var/PF controller, and set the control
mode to Var Control.
Set K
p
on var/PF controller. Synchronize the generator to the utility so that var control becomes active.
Verify that stable var control occurs. If the var control seems unstable, lower K
p
and try again. Assuming
operation appears stable, change the var setpoint in 10% steps and check for stable operation. Since K
i
is
zero at this point, there may be some error. Most importantly, verify that stable var control is achieved.
C-4 DGC-2020 Tuning PID Settings 9400200990 Rev X