Siemens 6MD85, Manual

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Table 9-4 Comparison of Synchrophasors and Conventional Measured Values
Synchrophasors of the PMU Measured Values from the Measuring Points
Continuous updating (measured value of current)
with, for example, 10 values per second (reporting
rate) Slow updating (typically every 5 seconds)
Every measured value has a time stamp No time stamp for the measured values
Phasor values of current and voltage (amplitude and
phase angle) RMS values without phase angle
The following figure shows the structure of such a Wide Area Monitoring System. The data delivered from the
PMUs on the PDC are transmitted via the Inter-Control Center Communications Protocol (ICCP) according to
DIN EN 60870-6 to the network control center.
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Figure 9-3 Structure of a Wide-Area Monitoring System with Phasor-Measurement Units
The phasor-measurement units each have 2 communication interfaces: an Ethernet module for synchrophasor
communication via IEEE C37.118 and another module for communication with the substation automation
technology, for example, through the IEC 61850 protocol.
The central evaluation system, e.g. SIGUARD PDP Phasor Data Processor, receives the data, files, archives them
and graphically displays them on a User Interface. In this system, a self-checking function may also be
performed, for example, on undamped power swings. The further distribution of information to other PDCs or
to a control station is done here.
To maintain the required maximum errors (TVE) required in the standard IEEE C37.118, the time tolerance
relative to the UTC time reference (UTC = Universal Time Coordinated) may be maximum 10 μs. Therefore, the
device must be directly synchronized with a GPS precise time signal for the correct function of the PMU.
Phasors
A phasor u(t) = Ue jωt can be displayed as a phasor that moves counterclockwise in the complex plane at the
angular frequency ω. Therefore, the voltage function u(t) = Re{u(t)} is obtained as a projection of the phasor
u(t) on the real axis.
Measured Values, Energy Values, and Supervision of the Primary System
9.5 Phasor Measurement Unit (PMU)
SIPROTEC 5, High-Voltage Bay Controller, Manual 1001
C53000-G5040-C015-9, Edition 11.2017