GE N60 Instruction Manual page 552

COMMANDS MENU CHAPTER 7: COMMANDS AND TARGETS
Figure 7-1: PMU one-shot FlexLogic operands
7.1.5.1 Testing accuracy of the PMU
The one-shot feature is used to test accuracy of the synchrophasor measurement. GPS-synchronized tests sets perform a
similar function to PMUs; instead of measuring the phasor from physical signals with respect to the externally provided
time reference, they produce the physical signals with respect to the externally provided time reference, given the desired
phasor values. Therefore the GPS-synchronized test sets cannot be automatically assumed more accurate than the PMUs
under test. This calls for a method to verify both the measuring device (PMU) and the source of signal (test set).
With reference to the following figure, the one-shot feature can be configured to trigger a high-accuracy scope to capture
both the time reference signal (rising edge of the 1 pps signal of the IRIG-B time reference) and the measured waveform.
The high-accuracy high-sampling rate record of the two signals captured by the scope can be processed using digital
tools to verify the magnitude and phase angle with respect to the time reference signal. As both the time reference and the
measured signals are raw inputs to the PMU under test, their independently captured record, processed using third-party
software, is a good reference point for accuracy calculations. Such a record proves useful when discussing the test results,
and can be retained as a part of the testing documentation.
Figure 7-2: Using the PMU one-shot feature to test synchrophasor measurement accuracy
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7.1.5.2 Collecting synchronized measurements ad hoc
The one-shot feature can be used for ad hoc collection of synchronized measurements in the network. Two or more PMUs
can be pre-scheduled to freeze their measurements at the same time. When frozen, the measurements can be collected
using the EnerVista software or a protocol client.
7-6 N60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL