ABB Relion 670 Series Applications Manual page 95

1MRK 511 407-UUS Rev. J
phasor channel. More information about preprocessor block is available in the section Signal
matrix for analog inputs SMAI.
6.1.3.1 Frequency reporting
By using patented algorithm the IED can track the power system frequency in quite wide range
from 9 Hz to 95 Hz. In order to do that, the three-phase voltage signal shall be connected to the
IED. Then IED can adapt its filtering algorithm in order to properly measure phasors of all current
and voltage signals connected to the 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 (
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
shows the selected channel as the reference for frequency and
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.
Phasor measurement unit RES670
Application manual
PhasorXUseFreqSrc ) to be used as a source of frequency data for
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Wide area measurement system
GUID-4F3BA7C7-8C9B-4266-9F72-AFB139E9DC21 v2
FREQREFCHSEL output
FREQREFCHERR output states if
Section 6
89