Manual 02007
DSLC Digital Synchronizer and Load Control
Woodward
67
While the power measurement is of the greatest interest, other functions may
also be derived from the raw data. These are
where T is the sampling period. The sampling period is derived from the zero
crossings of the A phase voltage signal.
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 wave form over a number of cycles of the input are
taken to get the power measurement.
Power System Management Concepts
This section provides a review of the operation of droop, isochronous,
droop/isochronous, isochronous load sharing, and base load. These concepts
provide an understanding for power management.
Droop
Droop is a decrease in speed or frequency, proportional to load. That is, as the
load increases, the speed or frequency decreases as illustrated in Figure 5-1.
This reduction in speed is accomplished with negative feedback. The feedback
increases as the system is loaded.