GE D30 series Instruction Manual

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Contents

GE Multilin D30 Line Distance Protection System 5-1415 SETTINGS 5.6 GROUPED ELEMENTS5• The POWER SWING UN/BLOCK FlexLogic operand shall be used to block those protection elements that are intended tobe blocked under power swings, but subsequently unblocked should a fault occur after the power swing blocking con-dition has been established.• The POWER SWING 50DD FlexLogic operand indicates that an adaptive disturbance detector integrated with the ele-ment has picked up. This operand will trigger on faults occurring during power swing conditions. This includes boththree-phase and single-pole-open conditions.• The POWER SWING INCOMING FlexLogic operand indicates an unstable power swing with an incoming locus (the locusenters the inner characteristic).• The POWER SWING OUTGOING FlexLogic operand indicates an unstable power swing with an outgoing locus (the locusleaving the outer characteristic). This operand can be used to count unstable swings and take certain action only afterpre-defined number of unstable power swings.• The POWER SWING TRIP FlexLogic operand is a trip command.The settings for the power swing detect element are described below:• POWER SWING FUNCTION: This setting enables and disables the entire power swing detection element. The settingapplies 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 char-acteristics of the power swing detect element. The operating principle is not affected. The “Mho” characteristics use theleft and right blinders.• POWER SWING MODE: This setting selects between the two-step and three-step operating modes and applies toboth power swing blocking and out-of-step tripping functions. The three-step mode applies if there is enough spacebetween the maximum load impedances and distance characteristics of the relay that all three (outer, middle, andinner) characteristics can be placed between the load and the distance characteristics. Whether the spans betweenthe outer and middle as well as the middle and inner characteristics are sufficient should be determined by analysis ofthe 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 leavesmore space in heavily loaded systems to place two power swing characteristics between the distance characteristicsand 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. Thesupervision responds to the positive sequence current.• POWER SWING FWD REACH: This setting specifies the forward reach of all three mho characteristics and the innerquadrilateral characteristic. For a simple system consisting of a line and two equivalent sources, this reach should behigher than the sum of the line and remote source positive-sequence impedances. Detailed transient stability studiesmay be needed for complex systems in order to determine this setting. The angle of this reach impedance is specifiedby the POWER SWING FWD RCA setting.• POWER SWING QUAD FWD REACH MID: This setting specifies the forward reach of the middle quadrilateral charac-teristic. The angle of this reach impedance is specified by the POWER SWING FWD RCA setting. The setting is not used ifthe shape setting is “Mho”.• POWER SWING QUAD FWD REACH OUT: This setting specifies the forward reach of the outer quadrilateral charac-teristic. The angle of this reach impedance is specified by the POWER SWING FWD RCA setting. The setting is not used ifthe shape setting is “Mho”.• POWER SWING FWD RCA: This setting specifies the angle of the forward reach impedance for the mho characteris-tics, angles of all the blinders, and both forward and reverse reach impedances of the quadrilateral characteristics.• POWER SWING REV REACH: This setting specifies the reverse reach of all three mho characteristics and the innerquadrilateral characteristic. For a simple system of a line and two equivalent sources, this reach should be higher thanthe positive-sequence impedance of the local source. Detailed transient stability studies may be needed for complexsystems to determine this setting. The angle of this reach impedance is specified by the POWER SWING REV RCA settingfor “Mho”, and the POWER SWING FWD RCA setting for “Quad”.• POWER SWING QUAD REV REACH MID: This setting specifies the reverse reach of the middle quadrilateral charac-teristic. The angle of this reach impedance is specified by the POWER SWING FWD RCA setting. The setting is not used ifthe shape setting is “Mho”.