One of the important functions of a PMU is reporting a very accurate system frequency to the PDCclient. In the IED, each of the PMUREPORT instances is able to report an accurate frequency. Eachvoltage-connected preprocessor block (SMAI block) delivers the frequency data, derived from theanalog input AC voltage values, to the respective voltage phasor channel. Every phasor channel hasa user-settable parameter (PhasorXUseFreqSrc) to be used as a source of frequency data forreporting 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 anuninterrupted reporting of the system frequency to the PDC client. In this frequency sourceselection 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 higherchannel numberAs a result, the first voltage phasor is always the one delivering the system frequency to the PDCclient and if, by any reason, this voltage gets disconnected then the next available voltage phasoris 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 willbe automatically selected again as the frequency source. There is also an output available on thecomponent 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 therespective PMUREPORT instance on Local HMI under Test/Function status/Communication/Station Communication/PMU Report/PMUREPORT:1/Outputs, where theFREQREFCHSEL outputshows the selected channel as the reference for frequency andFREQREFCHERR output states ifthe reference frequency is good, or if there is an error or if the reference channel is unavailable. Formore information refer to the table PMUREPORT monitored data.PID-6244-MONITOREDDATA v2Table 11: PMUREPORT Monitored dataName Type Values (Range) Unit DescriptionTIMESTAT BOOLEAN 1=Ready0=Fail- Time synchronization statusFREQ REAL - Hz FrequencyFREQGRAD REAL - - Rate of change of frequencyFREQREFCHSEL INTEGER - - Frequency reference channel numberselectedFREQREFCHERR BOOLEAN 0=Freq ref notavailable1=Freq ref error2=Freq refavailable- Frequency reference channel errorFREQTRIG BOOLEAN - - Frequency triggerDFDTTRIG BOOLEAN - - Rate of change of frequency triggerMAGHIGHTRIG BOOLEAN - - Magnitude high triggerMAGLOWTRIG BOOLEAN - - Magnitude low trigger6.1.3.2 Reporting filters GUID-D39153B5-81CE-4C1F-A816-C7A4C3407048 v2The PMUREPORT function block implements the reporting filters designed to avoid aliasing as thereporting frequency is lower than the sample/calculation frequency. This means, theSection 6 1MRK 511 364-UUS AWide area measurement system82Application manual
