Security - GE N60 Instruction Manual

7 COMMANDS AND TARGETS
TESTING ACCURACY OF THE PMU:
The one-shot feature can be used to test accuracy of the synchrophasor measurement. GPS-synchronized tests sets per-
form a similar function to PMUs: instead of measuring the phasor from physical signals with respect to the externally pro-
vided 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 figure below, the one-shot feature could 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 mea-
sured signals are raw inputs to the PMU under test, their independently captured record, processed using third-party soft-
ware, is a good reference point for accuracy calculations. Such a record proves useful when discussing the test results, and
should be retained as a part of the testing documentation.
Note that the PMU under such test does not have to be connected to a real GPS receiver as the accuracy is measured with
respect to the timing reference provided to the PMU and not to the absolute UTC time. Therefore a simple IRIG-B genera-
tor could be used instead. Also, the test set does not have to support GPS synchronization. Any stable signal source can
be used. If both the PMU under test and the test set use the timing reference, they should be driven from the same IRIG-B
signal: either the same GPS receiver or IRIG-B generator. Otherwise, the setpoints of the test set and the PMU measure-
ments should not be compared as they are referenced to different time scales.
Figure 7–2: USING THE PMU ONE-SHOT FEATURE TO TEST SYNCHROPHASOR MEASUREMENT ACCURACY
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 PMU
can be pre-scheduled to freeze their measurements at the same time. When frozen the measurements could be collected
using EnerVista UR Setup or a protocol client.
i 
PATH: COMMANDS

SECURITY

 SECURITY

GE Multilin N60 Network Stability and Synchrophasor Measurement System
ADMINISTRATOR
LOGOFF: No
ENGINEER
LOGOFF: No
OPERATOR
LOGOFF: No
CLEAR SECURITY DATA:
7.1 COMMANDS
Range: Yes, No
Default: No
Range: Yes, No
Default: No
Range: Yes, No
Default: No
Range: Yes, No
Default: No
7
7.1.7 SECURITY
7-5