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N60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL
GROUPED ELEMENTS
CHAPTER 5: SETTINGS
5
•
POWER SWING OUTER
,
POWER SWING MIDDLE
,
POWER SWING INNER
,
POWER SWING TMR2 PKP
,
POWER SWING TMR3 PKP
, and
POWER SWING TMR4 PKP
are auxiliary operands that facilitate testing and special applications
•
POWER SWING BLOCK
blocks selected protection elements, such as distance functions
•
POWER SWING UN/BLOCK
blocks those protection elements that are intended to be blocked under power swings, but
subsequently unblocked when a fault occurs after the power swing blocking condition has been established
•
POWER SWING 50DD
indicates that an adaptive disturbance detector integrated with the element has picked up. This
operand triggers on faults occurring during power swing conditions. This includes both three-phase and single-pole-
open conditions.
•
POWER SWING INCOMING
indicates an unstable power swing with an incoming locus (the locus enters the inner
characteristic)
•
POWER SWING OUTGOING
indicates an unstable power swing with an outgoing locus (the locus leaving the outer
characteristic). This operand can be used to count unstable swings and take certain action only after a pre-defined
number of unstable power swings.
•
POWER SWING TRIP
is a trip command
The settings for the power swing detect element are as follows.
POWER SWING FUNCTION
— This setting enables and disables the power swing detection element. The setting applies to
both power swing blocking and out-of-step tripping functions.
POWER SWING SOURCE
— The source setting identifies the signal source for both blocking and tripping functions.
POWER SWING SHAPE
— This setting selects the shapes (either “Mho” or “Quad”) of the outer, middle, and inner
characteristics of the power swing detect element. The operating principle is not affected. The “Mho” characteristics use
the left and right blinders.
POWER SWING MODE
— This setting selects between the two-step and three-step operating modes and applies it to both
power swing blocking and out-of-step tripping functions. The three-step mode applies if there is enough space between
the maximum load impedances and distance characteristics of the relay that all three (outer, middle, and inner)
characteristics can be placed between the load and the distance characteristics. Whether the spans between the outer
and middle as well as the middle and inner characteristics are sufficient is determined by analysis of the fastest power
swings expected in correlation with settings of the power swing timers.
The two-step mode uses only the outer and inner characteristics for both blocking and tripping functions. This leaves more
space in heavily loaded systems to place two power swing characteristics between the distance characteristics and the
maximum load, but allows for only one determination of the impedance trajectory.
POWER SWING SUPV
— A common overcurrent pickup level supervises all three power swing characteristics. The
supervision responds to the positive-sequence current.
POWER SW I2 SUPV ENAB
— This setting is to enable I2 supervision logic through a FlexLogic operand, which is used to
detect the presence of significant unbalance in current signals, such as during fault conditions. Under these conditions, the
POWER SWING BLOCK
operand is not asserted.
POWER SWING I2 SUPV
— This setting specifies the threshold of the I2 supervision logic.
POWER SWING FWD REACH
— This setting specifies the forward reach of all three mho characteristics and the inner
quadrilateral characteristic. For a simple system consisting of a line and two equivalent sources, this reach needs to be
higher than the sum of the line and remote source positive-sequence impedances. Detailed transient stability studies can
be needed for complex systems in order to determine this setting. The angle of this reach impedance is specified by the
POWER SWING FWD RCA
setting.
POWER SWING QUAD FWD REACH MID
— This setting specifies the forward reach of the middle quadrilateral characteristic.
The angle of this reach impedance is specified by the
POWER SWING FWD RCA
setting. The setting is not used if the shape
setting is “Mho.”
POWER SWING QUAD FWD REACH OUT
— This setting specifies the forward reach of the outer quadrilateral characteristic.
The angle of this reach impedance is specified by the
POWER SWING FWD RCA
setting. The setting is not used if the shape
setting is “Mho.”
POWER SWING FWD RCA
— This setting specifies the angle of the forward reach impedance for the mho characteristics,
angles of all blinders, and both forward and reverse reach impedances of the quadrilateral characteristics.