Basler Electric DGC-2020HD - Manual (Page 371)

9469300990 Rev B 361
Tuning PID Settings
The DGC-2020HD utilizes four controllers to accomplish synchronization, load sharing, and speed trim
functions. These consist of a voltage controller, a var/PF controller, a speed controller, and a kW load
controller.
Voltage and Speed Controllers
The voltage and speed controllers are in effect when the DGC-2020HD is synchronizing the generator to
a bus. When synchronizing, these controllers adjust the speed and voltage output of the generator to
match that of the bus.
kW Load Controller
After the generator is paralleled to a bus, the kW load controller controls the kW output of the machine to
share equally on a percentage basis with the other generators on the bus. All generators participating in
load sharing are connected together with load share lines which are used to communicate load share
information between the machines. When the generator is paralleled to the utility, the kW load controller
causes the unit to produce wattage at a level equal to the base load setpoint.
Var/PF Controller
When the generator is not paralleled to the utility, the var/PF controller operates in voltage droop mode for
var/PF sharing between the machines. The var/PF controller can operate in either var or PF control mode
when the generator is paralleled to the utility.
When operating in var control mode, the machine produces reactive power at a level equal to the kvar
Setpoint setting. When in PF control mode, the var/PF controller regulates the reactive power output of
the machine to maintain the power factor specified by the PF Setpoint setting.
Speed Trim Function
When the generator is paralleled to the bus and load sharing is enabled, the speed trim function, if
enabled in all machines on the bus, ensures that the bus frequency is maintained at the frequency set by
the speed trim setting. Speed trim is in effect only in the situation where the generator breaker is closed
and load control is enabled. Speed trim is not in effect when the breaker is open, since the default mode
when the breaker is open is droop, and speed trim would counteract droop.
When load control is enabled, it is possible that load control could cause the system frequency to drift,
and speed trim can be employed to counteract the drift. The drift can occur due to inaccuracies in
measured kW vs. desired kW, since kW measurement accuracy is around 3%.
Tuning Parameters
The DGC-2020HD load share function utilizes PID (Proportional, Integral, Derivative) control to
accomplish load sharing, speed control, and voltage control. A brief description of the three main tuning
parameters, and their effects on system behavior, is presented below.
•
K
p
- Proportional Gain - The proportional term makes a change to the output that is proportional to
the current error value. The proportional response can be adjusted by multiplying the error by a
constant K
p
, called the proportional gain. Larger K
p
typically means faster response since the
larger the error, the larger the feedback to compensate. An excessively large proportional gain
will lead to process instability.
DGC-2020HD Tuning PID Settings