Woodward EGCP-2 - Generator Load Control

Manual 26174 EGCP-2 Engine Generator Control Package
Woodward 121
It is highly recommended that the automatic reactive load control in
the EGCP-2 be used for proper power conditioning throughout the
generator(s) load range. This is achieved by setting the Load Control
set point in the Configuration tuning menu to Normal, or Soft
Transfer (depending on the application), and the VAR/PF Control set
point in the Reactive Load Control tuning menu to VAR or PF control
(depending on the application). For more details on these functions
see the Real Load Control and Reactive Load Control sections of this
manual.
The percent level of the voltage bias output can be monitored in the I/O status
screen of the EGCP-2. This is a useful point to monitor during initial start of the
unit. By issuing Voltage Raise and Lower inputs to the control while operating in
the Test Mode, confirmation of proper generator voltage levels at various voltage
bias points can easily be made. Typically the generator voltage should change
no more than ±10% for a ±100% voltage bias output from the EGCP-2.
All other modes of generator set operation rely upon the Reactive Load Control
functions of the EGCP-2. See the information in the “Reactive Load Control”
section of the manual for more details on voltage and reactive load control.
Generator Load Control
Power Sensor Theory of Operation
The digital signal processing (DSP) power measurement technique used by the
EGCP-2 control involves periodic sampling of the voltage and current over an
integral number of waveforms. The microprocessor computes the product of the
voltage and current samples, then sums and averages the products to give a
computation of power.
Load Sensor Hardware Description
The digital load sensor gets timing information from the generator A phase
voltage signal. Voltages proportional to the voltage and load current for each
phase are routed to the sample-and-hold circuits of the A/D converters. The
simultaneous sampled values representing voltage and current are held when a
conversion-store signal is received from the microprocessor. Each input is then
converted and an interrupt is generated when all inputs are converted. The
microprocessor then reads the digital values from A/D registers. This procedure
is repeated at regular intervals to provide input for further signal processing.
To provide accuracy in the presence of noise and harmonics on the inputs,
multiple samples of each waveform over a number of cycles of the input are
taken to get the power measurement.
The EGCP-2 Control has four core modes of generator load control operation.
These four modes are:
 Droop
 Isochronous Load Sharing
 Base Load
 Process Control
The specific mode of generator control that the unit is in at any given time can be
monitored on the Control Overview status screen.