Adaptive quadrilateral characteristic distance relay
AssigneeABB Power T&D Company Inc.
InventorLifeng Yang
Life of this patent
Estimating the term…
Abstract
A quadrilateral characteristic relay system for determining a fault associated with a multiple-phase electric power transmission system is disclosed. The system dynamically adapts one line of the quadrilateral trip region to account for the interaction of load current and fault resistance. As a result of the adaptation, the system exhibits better overreach and underreach performance characteristics. The system employs impedance and voltage plane quadrilateral characteristics using negative sequence current as a proxy for fault current. In the voltage plane, the fault determination is made through a series of comparisons, avoiding computationally inefficient mathematical divisions.
Claims22
A system for monitoring at least one electric power transmission line for a fault condition within a predetermined distance from a measuring location, comprising:
- measuring means coupled to said electric power transmission line at said measuring location for measuring at least one line voltage phasor and at least one line current phasor, said line voltage phasor being indicative of an amplitude and phase associated with a voltage waveform and said line current phasor being indicative of an amplitude and phase associated with a current waveform;
- and,
- processing means for defining a quadrilateral trip region in a reference plane, said quadrilateral trip region being formed from at least four reference phasors each having a phase, and wherein the phase of at least one of said at least four reference phasors is periodically adapted based on a negative sequence current;
- said processing means being coupled to said measuring means for deriving a line signal having a phase from at least one of said line voltage phasor and said line current phasor and comparing said line signal to the at least four reference phasors such that the fault condition is detected.
A system for monitoring at least one electric power transmission line for a fault condition within a predetermined distance from a measuring location, wherein the electric power transmission line is part of a multiple phase electric power transmission system, comprising:
- measuring means coupled to said electric power transmission line at said measuring location for measuring at least one line voltage phasor and at least one line current phasor, said line voltage phasor being indicative of an amplitude and phase associated with a voltage waveform and said line current phasor being indicative of an amplitude and phase associated with a current waveform;
- means for determining a fault type wherein said fault type is one of a single-phase-to-ground and a phase-to-phase,
- processing means for defining a quadrilateral trip region in a voltage plane, said quadrilateral trip region being formed from at least four voltage reference phasors each having a phase, and wherein the phase of at least one of said at least four voltage reference phasors is periodically adapted by an angle .alpha., .alpha. being determined according to fault type such that for a single-phase-to-ground fault:
- .alpha.=arg(I.sub.relaya)-arg(I.sub.a2)
- where:
- a comprises the faulted phase;
- I.sub.a2 comprises the negative sequence current of the faulted phase;
- I.sub.relaya is the relay current in the faulted phase;
- and for a phase-to-phase fault:
- .alpha.=arg(I.sub.ab)-arg(I.sub.ab -I.sub.1dab)
- where:
- ab indicates the multiple faulted phases;
- I.sub.ab comprises the phase difference between a first faulted-phase current and a second faulted-phase current;
- and,
- I.sub.1dab comprises the difference between the first phase load current and the second phase load current;
- said processing means being coupled to said measuring means for deriving a line signal having a phase from said line voltage phasor and comparing the phase of said line signal to the phase of each of said at least four voltage reference phasors such that the fault condition is detected without performing mathematical division operations.
A process for monitoring at least one electric power transmission line for a fault condition within a predetermined distance from a measuring location, comprising the steps of:
- a) measuring at least one line voltage phasor and at least one line current phasor, said line voltage phasor being indicative of an amplitude and phase associated with a voltage waveform and said line current phasor being indicative of an amplitude and phase associated with a current waveform;
- b) defining a quadrilateral trip region in a reference plane, said quadrilateral trip region being formed from at least four reference phasors each having a phase;
- c) periodically adapting the phase of at least one of said at least four reference phasors based on a negative sequence current;
- d) deriving a line signal having a phase from said line voltage phasor and comparing the phase of said line signal to the phase of each of said at least four reference phasors such that the fault condition is detected.
A process for monitoring at least one electric power transmission line for a fault condition within a predetermined distance from a measuring location, wherein the electric power transmission line is part of a multiple phase electric power transmission system, comprising the steps of:
- a) measuring at least one line voltage phasor and at least one line current phasor, said line voltage phasor being indicative of an amplitude and phase associated with a voltage waveform and said line current phasor being indicative of an amplitude and phase associated with a current waveform;
- b) determining a fault type wherein said fault type is one of a single-phase-to-ground and a phase-to-phase, c) defining a quadrilateral trip region in a voltage plane, said quadrilateral trip region being formed from at least four voltage reference phasors each having a phase, and wherein the phase of at least one of said at least four voltage reference phasors is periodically adapted by an angle .alpha., .alpha. being determined according to fault type such that for a single-phase-to-ground fault:
- .alpha.=arg(I.sub.relaya)-arg(I.sub.a2)
- where:
- a comprises the faulted phase;
- I.sub.a2 comprises the negative sequence current of the faulted phase;
- I.sub.relaya is the relay current in the faulted phase;
- and for a phase-to-phase fault:
- .alpha.=arg(I.sub.ab)-arg(I.sub.ab -I.sub.1dab)
- where:
- ab indicates the multiple faulted phases;
- I.sub.ab comprises the phase difference between a first faulted-phase current and a second faulted-phase current;
- and,
- I.sub.1dab comprises the difference between the first phase load current and the second phase load current;
- deriving a line signal having a phase from said line voltage phasor and comparing the phase of said line signal to the phase of each of said at least four voltage reference phasors such that the fault condition is detected without performing mathematical division operations.
A system for monitoring at least one electric power transmission line for a fault condition within a predetermined distance from a measuring location, comprising:
- measuring means coupled to said electric power transmission line at said measuring location for measuring at least one line voltage phasor and at least one line current phasor, each line voltage phasor being indicative of an amplitude and phase associated with a voltage waveform and said line current phasor being indicative of an amplitude and phase associated with a current waveform;
- and,
- processing means for defining a quadrilateral trip region in an impedance plane, said quadrilateral trip region being formed from at least four impedance reference phasors each having a phase, and wherein the phase of at least one of said at least four impedance reference phasors is periodically adapted by the angle a based on the following equation:
- .alpha.=arg(I.sub.relaya)-arg(I.sub.a2)
- where:
- I.sub.relaya is the relay current;
- and
- I.sub.a2 is the negative sequence current;
- said processing means being coupled to said measuring means for deriving a measured impedance having a magnitude and phase and detecting a fault condition when said measured impedance is within the quadrilateral trip region.
A process for monitoring at least one electric power transmission line for a fault condition within a predetermined distance from a measuring location, comprising:
- measuring at least one line voltage phasor and at least one line current phasor, each line voltage phasor being indicative of an amplitude and phase associated with a voltage waveform and said line current phasor being indicative of an amplitude and phase associated with a current waveform;
- and,
- defining a quadrilateral trip region in an impedance plane, said quadrilateral trip region being formed from at least four impedance reference phasors each having a phase;
- periodically adapted at least one of said at least four impedance reference phasors by the angle .alpha. based on the following equation:
- .alpha.=arg(I.sub.relaya)-arg(I.sub.a2)
- where:
- I.sub.relaya is the relay current;
- and
- I.sub.a2 is the negative sequence current;
- said processing means being coupled to said measuring means for deriving a measured impedance having a magnitude and phase and detecting a fault condition when said measured impedance is within the quadrilateral trip region.
Dependencies are inferred from the claim text.