Siemens 6MD85, Manual

Page: 1003 / 1256

The number of phasors that are transmitted per second is configurable. The transmission rate is defined
according to IEEE C37.118 as the reporting rate. The reporting rate defines the number of phasors that are
transmitted per second. Extremely precise time synchronization is essential so that phasor measurement can
be carried out to enable phasors from different sites to be compared.
Reporting Rate
You use the configurable reporting rate (parameter
(_:10621:102) Reporting rate
) to specify the
number of telegrams that are compiled and sent to the PDC per second. It is adjustable, depending on the
rated frequency, and applies to all currents and voltages of the relevant PMU function group. If several PMU
function groups are created on the device, these can work with different reporting rates.
Total Vector Error (TVE)
The TVE describes the error between the actual and the measured values of the input signal. The Synchro-
phasor Standard IEEE 37.118 defines upper limiting values of 120 % V
N
and 200 % I
N
, among other things. Up
to these limiting values, the TVE of 1 % must not be exceeded for stationary signals. The standard defines the
2 performance classes, Class P and Class M, as ranges within which influencing variables are acceptable and
the TVE of ≤1 % must be maintained. The SIPROTEC 5 devices support Class P and Class M, which specify the
following influencing variables for a TVE of 1 %:
•
Signal frequency (relative to f
N
)
•
Signal magnitude (relative to 100 % nominal magnitude) for voltage and current
•
Phase angle (relative to 0°)
•
Harmonic distortions (relative to < 0.2 % (THD) up to the 50th harmonic
The following figure graphically represents the total vector error. As well as the amplitude, the TVE also enters
into the angle error.
Measured Values, Energy Values, and Supervision of the Primary System
9.5 Phasor Measurement Unit (PMU)
SIPROTEC 5, High-Voltage Bay Controller, Manual 1003
C53000-G5040-C015-9, Edition 11.2017