Winco DGC-2020 - Manual (Page 333)

9400200990 Rev K DGC-2020 Tuning PID Settings C-3
Var/PF Controller Tuning Procedure
Once desired voltage controller performance is obtained, the Var/PF controller can be tuned. Set all gains
in the Var/PF controller to 0, 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.
KP - Proportional Gain
Set an initial value of KP = 1 in the Var/PF Controller. Set the control mode to Var control.
Set KP 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, cut Kp in half and try again.
Assuming operation appears stable, change the Var setpoint in 10% steps and check for stable operation.
Since KI is zero at this point, there may be some small error. The important thing is that stable var control
is achieved.
Raise KP and repeat the test until unstable operation occurs. Then lower KP to half the value where
unstable operation was first attained.
If it is not possible to obtain stable Var controller operation, it may be necessary to reduce the control
gains in the voltage regulator that has its bias input driven by the LSM-2020.
KI - Integral Gain
Set the initial value of KI to be a tenth of the value set for KP.
Each time KI is set, synchronize the generator to the utility so that Var control becomes active. Check that
operation appears stable. Change the Var setpoint in 10% steps and check for stable operation. If the
system is not stable, lower KI and repeat the test.
Repeat this procedure, raising KI until the system is unstable, and then lower it to half the value where
instability is first attained.
KD - Derivative Gain
If the performance with KP and KI alone is satisfactory, you may stop here. Otherwise, KD, the derivative
controller gain, can be used in conjunction with TD, the noise filter constant, to reduce overshoot obtained
with the PI control. Setting KD and TD is an iterative process. Start with small values of KD such as 0.1 or
half the KI value, whichever is less.
TD is the constant of the low pass filter, which filters the controller input if high frequency interference
presents a problem when derivative control is employed. TD ranges from 0 to 1. TD=0 is no filtering,
TD=1 is heaviest filtering.
Tuning of KD can be achieved through the following steps. Raise KD, synchronize the generator to the
utility so that Var control becomes active, and check for stability. Change the Var setpoint in 10% steps
and check for stable operation. Raise KD repeating the tests until the system is unstable, and then lower
it to half the value where instability is first attained. If high frequency noise seems to be entering the
system, raise TD and tune KD again. TD ranges from 0 to 1. TD=0 is no filtering, TD=1 is heaviest
filtering.
If high frequency noise seems to be entering the system, set TD to 0.001 and see if the noise induced
behavior is reduced. Raise TD until desired reduction of noise behavior is achieved. Once TD has been
set, tune KD again. TD ranges from 0 to 1 with an increment of 0.001. TD=0 is no filtering, TD=1 is
heaviest filtering. If noise again appears to be a problem, adjust TD until desired behavior is achieved,
then retune KD.
Speed Controller Tuning Procedure
The speed controller is tuned prior to the KW load controller. Set Load Control to enabled, and speed trim
to enabled. Set all gains in both speed controller and kW load controller to 0. Start the generator and
close the breaker onto some load.
KP - Proportional Gain
Set an initial value of 1 for KP.
Each time KP is set, manually displace the governor lever if possible and see that control is regained in a
stable manner. If the governor cannot be perturbed in this manner, execute step responses by changing
the speed trim set point and check that the generator’s output approaches the new value in a stable
manner. Since KI is zero at this point, there may be some small difference between the generator’s output