Basler Electric DGC-2020HD - Manual (Page 373)

9469300990 Rev B 363
KI - Integral Gain
Set the initial value of KI to be a tenth of the value set for KP.
After setting a value for KI, disturb the system by changing the voltage on the bus input of the DGC-
2020HD so that the DGC-2020HD will try to follow it. Verify that the DGC-2020HD controls the voltage to
go to the new value in a stable manner. If it is not stable, lower the value of KI and repeat.
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. First set TD=0 to eliminate filtering. Raise
speed KD and check for stability. Each time KD is raised, disturb the system by changing the voltage on
the bus input of the DGC-2020HD so that the DGC-2020HD will try to follow it. Verify that the DGC-
2020HD controls the voltage to go to the new value in a stable manner. Raise KD until the system is
unstable, and then lower it to half the value where instability if first attained.
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 KD has been
set, tune KD again. TD ranges from 0 to 1 with an increment of 0.001. If noise again appears to be a
problem, adjust TD until desired behavior is achieved, and then retune KD.
var/PF Controller Tuning Procedure
Once desired voltage controller performance is obtained, the var/PF controller can be tuned. Set the Kp,
Ki, and Kd gains in the var/PF controller to 0. Set the Kg 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.
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 slight error. Most importantly, 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 with a bias input driven by the DGC-2020HD.
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.
DGC-2020HD Tuning PID Settings