Signal Sources - GE G30 Instruction Manual

SYSTEM SETUP
The
REVERSE PH ROTATION
This allows the G30 to follow the current phase rotation of the protected generator. For example, if the
setting is "ABC" but the condition defined for opposite phase rotation is true, then the phase rotation used for phasor
calculation switches to "ACB." This feature is only intended for use in special applications, such as pumped storage
schemes.
Typical application of using Reverse Phase Rotation is the pumped-storage hydroelectricity application. Water is pumped
from a lower elevation reservoir to a higher elevation (pumping or motor mode) during the off-peak period when low-cost
surplus electricity is available, and during periods of high electrical demand, the stored water is released through turbines
to produce electricity (generator mode), where pump operation is realized through phase rotation reversal operation
because the hydraulic units are designed to operate as turbines when rotating in one direction and as pumps when
rotating in the opposite direction.
When the operand assigned to the
defined by the
PHASE ROTATION
the opposite, ACB for the same example. Note that after successful rotation switching, the next switching is allowed only
after nine power cycles.
Typically, different relay setting groups are used to protect pumping operation mode and generating operation mode of
the hydraulic units respectively, therefore the logic for switching setting groups can be directly used to control the
.
PH ROTATION
Every time rotation change is performed, protection is blocked for three power cycles.
The
FREQUENCY AND PHASE REFERENCE
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
5
signals is used for frequency metering and tracking (V
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.
Phase angle of the reference signal always displays zero degrees and all other phase angles are relative to this signal. If the
pre-selected reference signal is not measurable at a given time, the phase angles are not referenced.
The phase angle referencing is done via a phase locked loop, which can synchronize independent UR-series relays if they
have the same AC signal reference. This results in very precise correlation of phase angle indications between different UR-
series relays.
FREQUENCY TRACKING
frequency applications.
The frequency tracking feature functions only when the G30 is in the "Programmed" mode. If the G30 is "Not
Programmed," then metering values are available but can exhibit significant errors.
Systems with an ACB phase sequence require special consideration. See the Phase Relationships of Three-phase
Transformers section of chapter 5.

5.5.3 Signal sources

SETTINGS  SYSTEM SETUP  SIGNAL SOURCES  SOURCE 1(4)
 SOURCE 1

5-144
setting allows the user to dynamically change the phase rotation used for phasor calculations.
REVERSE PH ROTATION
setting, ABC for example. When this operand is logical "1," the phase rotation changes to
setting determines which signal source is used (and hence which AC signal) for
is set to "Disabled" only in unusual circumstances; consult GE Grid Solutions for special variable-
SOURCE 1 NAME:

SRC 1
SOURCE 1 PHASE CT:

None
setting is logical "0," the phase rotation is matching the one
= V ), while Clarke transformation of the phase
ANGLE REF A
= (2V - V - V ) / 3) for better performance during fault,
FREQUENCY A B C
Range: up to 20 alphanumeric characters
Range: None, F1,... up to any 6 CTs. Only Phase CT
inputs are displayed.
G30 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
PHASE ROTATION
REVERSE