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[User Guide]
Purpose
CCEX is
responsible for executing NTMC capacitor control functions. This
means running one or more of the following algorithms: VAr control, power factor
control, current control, voltage control, temperature control, and time
control. The module also does recording of demand, reactive power, power factor,
and any other input parameter relevant to the algorithms being used, as well as
capacitor bank activity logs. The sections below summarize these activities.
Data Organization
The
module maintains a list substations
and schedules. Every
substation gets its own list of feeders, and every feeder its respective
list of capacitors. In addition, feeders are also responsible for
importing all measured input parameters, such as demand and reactive power.
Power factor is computed from the two mentioned inputs. Each capacitor gets
associated with one of the schedules. Substation demand, and reactive power,
should they be of interest, are computed by summing up the respective feeder
contributions. Substation power factor is calculated from the two sums. Global
demand, and reactive power, should they be of interest, are computed by summing
up the respective substation contributions. Global power factor is calculated
from the two sums. Not all of these are usually relevant at any one
installation, CCEX simply provides tools to cover as many possibilities as
possible.
Management Strategies
Capacitor control can be done on a feeder level, substation level, or
global level. CCEX is a tool which can be programmed to do any of the above. The
choice depends on the details of the installation, such as substation and feeder
distribution, the nature and location of customer loads, circuit topology,
capacitor bank locations, measurement point locations, and input parameters
being used, as well as the type of control applied (see Issues in Capacitor
Control ). In all cases capacitors can be sorted in any way desired to
control the order in which they are put on-line, and off-line. Every capacitor
can be put in manual mode which means that it is left out of any automatic
control operations. A safety control timer can be defined for each bank.
The
window caption above shows a real world situation - a feeder supplying a large customer coming on-line in
the early morning hours. The feeder has two 600 kVAr banks located close to the
customer. As reactive power increases the two banks are put on-line by CCEX as needed.
Types of Control
By using demand and reactive power inputs CCEX can execute VAr or
power factor control tied to a SCADA polling cycle. By associating each
capacitor with a (possibly shared) management schedule the module can do time
control. By importing another input and interpreting it appropriately CCEX
can run voltage, current, or temperature control
algorithms. By combining several of the inputs customer specific combination
control algorithms are available.
More
discussion of above algorithms can be found
here.
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