GE D30 series, Инструкция по эксплуатации

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CHAPTER 5: SETTINGS SYSTEM SETUP
D30 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 5-143
5
One bank of phase/auxiliary VTs can be set, where voltage banks are denoted in the following format (X represents the
module slot position letter):
Xa, where X = {F} and a = {5}
See the Introduction to AC Sources section at the beginning of this chapter for details.
With VTs installed, the relay can perform voltage measurements as well as power calculations. Enter the
PHASE VT F5
CONNECTION
made to the system as “Wye” or “Delta.” An open-delta source VT connection is entered as “Delta.”
5.5.2 Power system
SETTINGS  SYSTEM SETUP  POWER SYSTEM
The power system
NOMINAL FREQUENCY
value is used as a default to set the digital sampling rate if the system frequency
cannot be measured from available signals. This can happen if the signals are not present or are heavily distorted. Before
reverting to the nominal frequency, the frequency tracking algorithm holds the last valid frequency measurement for a
safe period of time while waiting for the signals to reappear or for the distortions to decay.
The phase sequence of the power system is required to properly calculate sequence components and power parameters.
The
PHASE ROTATION
setting matches the power system phase sequence and informs the relay of the actual system phase
sequence, either ABC or ACB. CT and VT inputs on the relay, labelled as A, B, and C, must be connected to system phases A,
B, and C for correct operation.
The
FREQUENCY AND PHASE REFERENCE
setting determines which signal source is used (and hence which AC signal) for
phase angle reference. The AC signal used is prioritized based on the AC inputs configured for the signal source. Phase
voltages takes precedence, followed by auxiliary voltage, then phase currents, and finally ground current.
For three phase selection, phase A is used for angle referencing (V
ANGLE REF
= V
A
), while Clarke transformation of the phase
signals is used for frequency metering and tracking (V
FREQUENCY
= (2V
A
- V
B
- V
C
) / 3) for better performance during fault,
open pole, and VT and CT fail conditions.
The phase reference and frequency tracking AC signals are selected based upon the source configuration, regardless of
whether or not a particular signal is actually applied to the relay.

AUXILIARY VT F5
CONNECTION: Vag
Range: Vn, Vag, Vbg, Vcg, Vab, Vbc, Vca

AUXILIARY VT F5
SECONDARY: 66.4 V
Range: 25.0 to 240.0 V in steps of 0.1

AUXILIARY VT F5
RATIO: 1.00 :1
Range: 1.00 to 24000.00 in steps of 0.01
The nominal
PHASE VT F5 SECONDARY
voltage setting is the voltage across the relay input terminals when nominal
voltage is applied to the VT primary.
For example, on a system with a 13.8 kV nominal primary voltage and with a 14400:120 volt VT in a delta
connection, the secondary voltage is 115; that is, (13800 / 14400) × 120. For a wye connection, the voltage value
entered must be the phase to neutral voltage, which is 115
/
= 66.4.
On a 14.4 kV system with a delta connection and a VT primary to secondary turns ratio of 14400:120, the voltage
value entered is 120; that is, 14400 / 120.

POWER SYSTEM


NOMINAL FREQUENCY:
60 Hz
Range: 25 to 60 Hz in steps of 1

PHASE ROTATION:
ABC
Range: ABC, ACB

FREQUENCY AND PHASE
REFERENCE: SRC 1
Range: SRC 1, SRC 2

FREQUENCYTRACKING:
Enabled
Range: Disabled, Enabled