Alstom MiCOM P545 - 1.4.1 Measured voltages and currents; 1.4.2 Sequence voltages and currents; 1.4.3 Slip frequency; 1.4.4 Power and energy quantities

Measurements and Recording P54x/EN MR/La4
MiCOM P543, P544, P545 & P546
(MR) 8-11
MR
1.4.1 Measured voltages and currents
The relay produces both phase to ground and phase to phase voltage and current values.
They are produced directly from the DFT (Discrete Fourier Transform) used by the relay
protection functions and present both magnitude and phase angle measurement.
Currents mentioned above can be seen on the Measurement 1 column. P54x also shows
local and remote currents in Measurement 3 column. These currents have the same
treatment as the currents used for differential protection purposes.
1.4.2 Sequence voltages and currents
Sequen
ce quantities are produced by the relay from the measured Fourier values; these are
displayed as magnitude and phase angle values.
1.4.3 Slip frequency
The relay p
roduces a slip frequency measurement by measuring the rate of change of phase
angle, between the bus and line voltages, over a one-cycle period. The slip frequency
measurement assumes the bus voltage to be the reference phasor.
1.4.4 Power and energy quantities
Usi
ng the measured voltages and currents the relay calculates the apparent, real and
reactive power quantities. These are produced on a phase by phase basis together with
three-phase values based on the sum of the three individual phase values. The signing of
the real and reactive power measurements can be controlled using the measurement mode
setting. The four options are defined in the table below:
Measurement mode Parameter Signing
0
(Default)
Export Power
Import Power
Lagging Vars
Leading VArs
+
–
+
–
1
Export Power
Import Power
Lagging Vars
Leading VArs
–
+
+
–
2
Export Power
Import Power
Lagging Vars
Leading VArs
+
–
–
+
3
Export Power
Import Power
Lagging Vars
Leading VArs
–
+
–
+
In addition to the measured power quantities the relay calculates the power factor on a
phase by phase basis in addition to a three-phase power factor.
These power values are also used to increment the total real and reactive energy
measurements. Separate energy measurements are maintained for the total exported and
imported energy. The energy measurements are incremented up to maximum values of
1000 GWhr or 1000 GVARhr at which point they will reset to zero, it is also possible to reset
these values using the menu or remote interfaces using the reset demand cell.