7
7.1 Phasor Measurement Unit (PMU)
52 Digital Fault Recorder, SIMEAS R-PMU, Manual
E50417-H1076-C360-A5, Release 10.2012
7.1 Phasor Measurement Unit (PMU)
The SIMEAS R-PMU is equipped with an integrated Phasor Measurement Unit (PMU) according
to the IEEE Std. C37.118 - 2005. Among other things, this standard defines among others PMU
quality criteria and the data formats.
At absolute instants of time, which are defined by the reporting rate, the PMU determines the
phasors from the measured values and sends them to a Phasor Data Concentrator (PDC).
The phasor measurement requires a highly precise time synchronization (<5 µs) of the SIMEAS
R-PMU device; especially if phasors of different locations are to be compared to each other.
Phasor Data Concentrator (PDC)
A PDC continuously receives data from one or several PMU devices. The Phasor Data
Concentrator can switch the PMU ON or OFF and read out its configurations and channel
descriptions. The data received by the PDC is visualized and may be stored in a database if
necessary.
Complex phasors
A phasor v
(t) = Ve
j
ω
t
can be displayed as a pointer that rotates anticlockwise with the angular
velocity ω in the complex plane. The voltage v(t) = Re{v(t)} is a result of the projection of the
phasor v(t) on the real axis.
Figure 7-1 Geometrical illustration of a phasor
v(t)
t
1
v(t
1
)
t
2
t
3
t
4
t
5
ϕ
0
/ω
t
Τ = 1/f =2π /ω
V
t = 0
ϕ
0
ωt
1
ω
v
(t
1
)
v(t
1
)
Re{v(t)}
t
3
t
2
t
4
t
5
Im{v(t)}
V
0
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