2.6 Protection parameter supervision at the beginning of
testing
The Project Team was also sensitive to the need for protection
setting verification and consistency, being acutely aware of
the learning points from recent well-publicized supply interruptions
traced to erroneous protection settings [6]. Before the
overall test of a protection relay starts, it is recommended to
compare present settings of the protection relay to the settings
that are already contained in the database. This mechanism
shows differences on the protection device since last testing.
This mechanism helps the user to resolve conflicts that could
cause inappropriate response of a protection device to the test
procedure or setting study. In case of differences being identified
between the historic and present settings, the user must
decide if a change in data in the IT system or in the protection
device is more appropriate.
2.7 The history or protection parameters and testing results
Every electrical power system network is an evolving entity
that changes its nominal states all the time. Different network
states require different protection settings. The Project Team
looked to have an IT system solution that would be capable to
"inherit" the whole setting history of the protection device.
Historic information is useful for users who are dealing with
different states of network for the first time. All setting data
must be linked to appropriate protection testing data.