Page 231 - Decision Making Applications in Modern Power Systems

Role of microphasor measurement unit Chapter | 7 195

comparing the SCADA data consistency with µPMU data that uses a sep-
arate independent cyber-network. Cyberattacks can only go undetected if
both the networks are hacked in exact coordination, which is an
extremely difficult task. The µPMU can also decide cyberattack instants
by identifying unanticipated operations or change in topology through its
synchronized measurements.
6. Fault-induced delayed voltage recovery (FIDVR) detection: The modern
distribution system has numerous number of induction motors. When
there is low voltage due to a fault in the grid, the induction motors get
stalled. Just after the fault is cleared, these stalled motors consume a
large current, which does not allow the distribution voltage recover in a
timely manner. Hence, the motors get tripped, and the voltage finally
comes to a nominal value. This is known as FIDVR [29]. The excessive
current flow in the motor can reduce the life of the motors. FIDVR
causes voltage sag for several of seconds, and when the induction motors
trip, it causes a sudden over voltages due to the capacitors that are used
to boost up the voltage in the FIDVR condition. This sudden overvoltage
affects all the consumers. Hence, FIDVR mitigation is a major issue.

Through its rapid data monitoring capability and suitable time sampling,
µPMU can come to aid in detecting and diagnosing FIDVR. Although instal-
ling µPMU just for FIDVR may not justify its cost, FIDVR diagnosis can be
incorporated as an additional function of the µPMU.
The µPMU requirements for the above applications in terms of resolution,
accuracy, latency, and continuity are tabulated in Table 7.1 [12]. However,
the applications of µPMU cannot be confined to the above applications only.
As the modern distribution is continuously evolving, various applications of
µPMU are emerging, which is increasing the foothold of µPMU in the distri-
bution system. Some other applications involve control of voltage in the
power system (other than the islanded system), health monitoring of various
distribution system equipment, oscillation detection, power quality monitor-
ing, etc. The extent of application of µPMU in making various distributions
for situation awareness will get more justified with increase in time.

7.6 Open microphasor measurement unit data
for research study
To advance the research of µPMU in distribution system application, a data
set of µPMU data is provided freely by LBNL [30,31]. The µPMU has a
sampling rate of 512 samples per cycle. Twelve streams of 120 Hz precise
values with a GPS time accuracy up to 100 ns are being provided by each
µPMU. The data consists of three-phase current and voltage magnitude along
with the phase angle acquired by three µPMUs at LBNL from different buses
in distribution system. The data provided is for the time frame between