Automatic Generator Loading Functions - Woodward EGCP-2 Operation Manual

EGCP-2 Engine Generator Control Package Manual 26086
The advantage of base loading over droop is that when separating from a Mains,
there is no frequency change. Simply removing the bias signal required to
maintain the base load reference on breaking from the Mains (mains CB Aux
open) returns the system to isochronous load control.
The EGCP-2 is only allowed to parallel with the mains in a Mains Parallel
operating mode. When configured for this type of operation, the EGCP-2 will
operate in either a base load or process control mode while in parallel with the
mains. The EGCP-2 automatically switches between base load and isochronous
operation depending upon whether or not the Mains Breaker CB Aux input is
closed at the same time the Generator CB Aux input is closed. If both the Mains
and the Generator CB AUX are closed, then the EGCP-2 realizes it is in parallel
with the mains, an operates in a base load control mode. The EGCP-2 will
operate in a process control mode, which is discussed later in this section, if both
the Process and Run with Load discrete inputs are active (on).

Automatic Generator Loading Functions

The automatic generator loading functions of the EGCP-2 control are designed to
be used with the speed control to automatically control the loading and unloading
of the generator. This accomplishes a bumpless transfer when paralleling the
generator to a load sharing or infinite bus system, or when separating a
generator from a system.
Process Control Description
The process control function of the EGCP-2 control will control any process
where the controlled parameter is determined by the generator load, and the
controlled parameter can be monitored as a 4–20 mA or 1–5 Vdc input signal.
The control compares the input signal to the Process Reference setpoint in the
Real Load Control tuning menu of the EGCP-2. This setpoint uses milliamps for
units so that it is easily related to the 4–20 mA or 1–5 Vdc input signal. The
EGCP-2 then adjusts the generator load to maintain the desired set point. The
EGCP-2 will only operate in a process control mode if it is configured to be a
Mains Parallel unit, and receives an Auto, Run With Load, and Process discrete
input. Also, the EGCP-2 can operate in a process soft transfer mode if the Load
Control Mode setpoint in the Configuration tuning menu is set for Soft Transfer,
and the Test discrete input is closed with the Run with Load and Process
discrete inputs. In a soft transfer mode, the EGCP-2 will load the generator or
generators (depending on the application) to the process reference level. Upon
reaching the reference value on the 4–20 mA or 1–5 Vdc input signal, the EGCP-
2 will open the mains breaker. This Soft Transfer mode is used to transfer the
supply of power for the load from the mains to the generator.
In process control mode, the Raise Load and Lower Load contact inputs operate
on the process control reference. The ramp time for these Raise and Lower Load
inputs while operating in process control mode are set in the Real Load Control
tuning menu, at the Process Raise and Process Lower Ramp Rate setpoint. This
setpoint is scaled in mA per second.
74 Woodward