6 Practical benefits of the new system
Besides all of the characteristics that are mentioned in the
sections above, the Project Team identified the following
advantages of the new system:
6.1 Central management of operative maintenance
The first advantage of the new system is to manage and coordinate
the operative maintenance from one central location.
The Power system maintenance manager manages and coordinates
maintenance strategies and targets their optimization
6.2 Implementation of know-how in the system - simplification
of routine protocols
Further, a most important characteristic of any such new systern
is the automation of complex protection functions in
digital protection devices. With user or system defined testing
protocols, there is a chance to test those function points that
have caused problems in the past. The new system is based on
embedded intelligence, meaning that the user can define a
detailed model of a protection device in that way that the
protection functions are recognized by the system.
This can be demonstrated by taking an example on one older
version of digital device. Input parameters can be copied only
from the device front panel. There are eight DIP switches,
earth fault (IE>) and unbalance setting (lub>, Iub>T).
There is a problem of finding out the values of other protection
parameters, which are hidden in the DIP switch combinations
or in the user manual of the device. The problem is
much larger if the users handle that specific kind of relay only
once or twice a year. The new system handles a protection
device model with intelligent transfer of critical information
into the XRIO module [3].
In the case of Elektro Ljubljana's system, the interface allows
the user to define all combinations of DIP switches and, as
result, the ability to get protection parameters of harmonic
factor value, the operation mode (with or without a double
star), time setting of earth fault protection and permitted THD
value where the defined inverse characteristics are available in
a manual. All these parameters are extracted from input values
without a single manual input operation. In case that user
decides to use a SOR protocol, the tolerances and testing
points of every protection function can be calculated and used
in a testing procedure.
The use of protection device model and the XRIO converter
eases the work with a protection device at a subsequent testing.
The test is easier and more accurate than it would be if all
parameters were to be calculated manually on site. In spite of
a fact that the user is not familiar with all details that are hidden
in a protection device, the routine test is always made on
a real protection data (even if they have been changed since
the last testing) and based on previous, real experience.
At this point, it can be appreciated that the system began to
act as an expert system. However, it must be emphasized that
Utility Technical Management must realize that an expert
system could be only as good as the user.