Siemens SIPROTEC, Руководство пользователя

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Functions
2.1 General
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
58
Calculation Example:
110 kV overhead line 150 mm
2
with the following data:
R'
1
= 0.19
Ω
/km
X'
1
= 0.42
Ω
/km
The line angle is computed as follows
In address
1105
the setting
Line Angle
=
66°
is entered.
Address
1511 Distance Angle
specifies the angle of inclination of the R sections of the distance protection
polygons. Usually you can also set the line angle here as in address
1105
.
The directional values (power, power factor, work and based on work: minimum, maximum, average and
threshold values), calculated in the operational measured values, are usually defined positive in the direction
towards the protected object. This requires that the connection polarity for the entire device was configured ac-
cordingly in the Power System Data 1 (compare also „Polarity of Current Transformers“, address
201
). But it
is also possible to define the „forward“ direction for the protection functions and the positive direction for the
power etc. differently, e.g. so that the active power flow (from the line to the busbar) is indicated in the positive
sense. Set under address
1107 P,Q sign
the option
reversed
. If the setting is
not reversed
(default),
the positive direction for the power etc. corresponds to the „forward“ direction for the protection functions.
The reactance per unit length value X' of the protected line is entered as reference value
x'
in address
1111
in
Ω
/km if the distance unit was set as kilometer (address
236
, see Section 2.1.2.1 at „Distance Unit“), or in
Ω
/miles if mile was selected as distance unit. The corresponding line length is entered in address
1113 Line
Length
in kilometers or in miles. If, after entry of the reactance per unit of line length in address
1111
or of the
line length in address
1113
, the distance unit is changed in address
236
, the line data must be entered again
for the revised distance unit.
The capacitance per unit length C' of the protected line is required for load current compensation, for double-
ended fault location and for compounding in overvoltage protection. Without these functions it is irrelevant. It is
entered as a reference value
c'
at address
1112
in
μ
F/km if kilometres was set as the distance unit (address
236
, see Section 2.1.2.1 at „Distance Unit“), or in
μ
F/miles if mile was set as distance unit. If the distance unit
is changed in address
236
after entry of the capacitance per unit and of the line length in address
1112
or of
the line length in address
1113
, the line data must be entered again for the changed distance unit.
For calculation of the capacitance of a line system, the entire line length, i.e. the sum of all line sections, must
be set in address
1114 Tot.Line Length
. For lines with more than two ends, this information is required for
charging current compensation.
When entering the parameters with a personal computer running the DIGSI software, the values can also be
entered as primary values. If the nominal quantities of the primary transformers (U,
I ) are set to minimum,
primary values allow only a rough setting of the value parameters. In such cases it is preferable to set the pa-
rameters in secondary quantities.
For conversion of primary values to secondary values the following applies in general: