ABB REC670 Applications Manual page 114

Section 6
Wide area measurement system
108
IED. This feature is essential for proper operation of the PMUREPORT function or
for protection during generator start-up and shut-down procedure.
This adaptive filtering is ensured by proper configuration and settings of all
relevant pre-processing blocks, see Signal matrix for analog inputs in the
Application manual. Note that in all preconfigured IEDs such configuration and
settings are already made and the three-phase voltage are used as master for
frequency tracking. With such settings the IED will be able to properly estimate the
magnitude and the phase angle of measured current and voltage phasors in this
wide frequency range.
One of the important functions of a PMU is reporting a very accurate system
frequency to the PDC client. In the IED, each of the PMUREPORT instances is
able to report an accurate frequency. Each voltage-connected preprocessor block
(SMAI block) delivers the frequency data, derived from the analog input AC
voltage values, to the respective voltage phasor channel. Every phasor channel has
a user-settable parameter (PhasorXUseFreqSrc) to be used as a source of frequency
data for reporting to the PDC client. It is very important to set this parameter to On
for the voltage-connected phasor channels. There is an automatic frequency source
selection logic to ensure an uninterrupted reporting of the system frequency to the
PDC client. In this frequency source selection logic, the following general rules are
applied:
• Only the voltage phasor channels are used
• The phasor channel with a lower channel number is prioritized to the one with
a higher channel number
As a result, the first voltage phasor is always the one delivering the system
frequency to the PDC client and if, by any reason, this voltage gets disconnected
then the next available voltage phasor is automatically used as the frequency source
and so on. If the first voltage phasor comes back, since it has a higher priority
compare to the currently selected phasor channel, after 500 ms it will be
automatically selected again as the frequency source. There is also an output
available on the component which shows if the reference frequency is good, error
or reference channel unavailable.
It is possible to monitor the status of the frequency reference channel (frequency
source) for the respective PMUREPORT instance on Local HMI under Test/
Function status/Communication/Station Communication/PMU Report/
PMUREPORT:1/Outputs, where the FREQREFCHSEL output shows the
selected channel as the reference for frequency and FREQREFCHERR output
states if the reference frequency is good, or if there is an error or if the reference
channel is unavailable. For more information refer to the table PMUREPORT
monitored data.
1MRK 511 401-UEN A
Bay control REC670 2.2 IEC
Application manual