Abstract: The present application discloses systems and methods related to protection of a reactor in an alternating current (AC) electric power system. In one embodiment, a system may include a protective action subsystem to implement a protective action based on identification of a fault condition associated with a reactor. A frequency determination subsystem may determine when a frequency of the AC voltage is outside of a range defined by a lower threshold and an upper threshold and may identify a change in the frequency associated with de-energization of a line in electrical communication with the reactor. A supervisory subsystem may restrain implementation of the protective action when the frequency is outside of the range or when the change in the frequency is associated with de-energization of the line in electrical communication with the reactor.

Abstract: The present disclosure pertains to devices, systems, and methods for monitoring a generator. In one embodiment, the system may include a measurement subsystem to receive a plurality of split-phase measurements of branch currents associated with the at least one generator. A split-phase transverse differential monitoring subsystem may receive the plurality of split-phase measurements of branch currents associated with the at least one generator and may generate an offset value representing a standing split-phase current. A protective action subsystem may generate a first protective action based on the phasor operating current.

Abstract: Breaker control units (BCUs) may include an output to selectively cause a circuit breaker (CB) to open and close a circuit, a voltage input to monitor a voltage of at least one of a bus and a line, a processor to calculate a point-on-wave switching time, and a remote input configured to be coupled to a remote intelligent electronic device (IED) to receive commands to selectively open and close the CB at a specified optimal time. Electric power systems may include such BCUs. Methods of switching CBs may include monitoring at least one of a bus and a line with a BCU and controlling switching of the CB at a predetermined point-on-wave value with onboard electronics of the BCU. The methods may additionally include calculating a trapped charge and/or a residual flux with an IED and causing the BCU to switch the CB at a specific optimum point-on-wave value.

Abstract: The present disclosure relates to systems and methods for protecting against and mitigating the effects of over-excitation of elements in electric power systems. In one embodiment, a system consistent with the present disclosure may comprise a point pair subsystem to receive a plurality of point pairs that define an over-excitation curve for a piece of monitored equipment. The system may receive a plurality of measurements corresponding to electrical conditions associated with the piece of monitored equipment. A logarithmic interpolation subsystem may determine a logarithmic interpolation corresponding to one of the plurality of measurements based on the plurality of point pairs. An over-excitation detection subsystem may detect an over-excitation condition based on the logarithmic interpolation, and a protective action subsystem may implement a protective action based on the over-excitation condition.

Abstract: Detection of, and protection against faults within a restricted earth fault (REF) zone of a transformer or a generator is disclosed herein. Security of the REF protection element uses comparison of a negative-sequence reference quantity. The REF condition is only detected when there is sufficient ground involvement and a fault in the reverse detection has not been detected. Dependability of the REF protection element in low-impedance grounded systems is improved by ensuring that the element operates when a zero-sequence reference quantity and a neutral operate quantity are orthogonal to each other. The REF protection element further determines an open CT condition and blocks detection of an REF fault upon determination of the open CT condition. A tripping subsystem may issue a trip command based upon detection of the REF condition.

Abstract: Detection of, and protection against faults within a restricted earth fault (REF) zone of a transformer or a generator is disclosed herein. Security of the REF protection element uses comparison of a negative-sequence reference quantity. The REF condition is only detected when there is sufficient ground involvement and a fault in the reverse detection has not been detected. Dependability of the REF protection element in low-impedance grounded systems is improved by ensuring that the element operates when a zero-sequence reference quantity and a neutral operate quantity are orthogonal to each other. The REF protection element further determines an open CT condition and blocks detection of an REF fault upon determination of the open CT condition. A tripping subsystem may issue a trip command based upon detection of the REF condition.

Abstract: The present disclosure relates to systems and methods for protecting against and mitigating the effects of over-excitation of elements in electric power systems. In one embodiment, a system consistent with the present disclosure may comprise a point pair subsystem to receive a plurality of point pairs that define an over-excitation curve for a piece of monitored equipment. The system may receive a plurality of measurements corresponding to electrical conditions associated with the piece of monitored equipment. A logarithmic interpolation subsystem may determine a logarithmic interpolation corresponding to one of the plurality of measurements based on the plurality of point pairs. An over-excitation detection subsystem may detect an over-excitation condition based on the logarithmic interpolation, and a protective action subsystem may implement a protective action based on the over-excitation condition.

Abstract: Detection and protection against electric power generator rotor turn-to-turn faults, rotor multi-point-to-ground faults, and rotor permanent magnet faults is provided herein. A fractional harmonic signal is used to determine the rotor fault condition. The fractional harmonic signal may be a fractional harmonic magnitude of the circulating current of one phase. The fractional harmonic may be a fractional harmonic magnitude of a neutral voltage. A tripping subsystem may issue a trip command based upon detection of a rotor turn-to-turn fault condition.

Abstract: Protection devices prevent damage to synchronous generators during loss-of-field events. In various embodiments, a first protective element is associated with a first protection zone to protect a generator from a loss-of-field event at full load. A second protective element is associated with a second protection zone to prevent thermal overload during underexcited operation of the generator and to protect from loss-of-filed at light load. A third protective element associated with a third protection zone limits operation of the generator within the generator's specific steady-state stability limits. A fourth protective element is associated with a fourth protection zone to provide an alarm prior to operation of the second protective element.

Abstract: Disclosed herein are systems for determining a broken conductor condition in a multiple-phase electric power delivery system. It has been observed that broken conductors pose a safety concern when occurring in the presence of people or vulnerable environmental conditions. Broken conductor conditions disclosed herein may be used to detect and trip the phase with the broken conductor, thus reducing or even eliminating the safety risk. Further, a distance to the opening may be determined.

Abstract: The present disclosure pertains to systems and methods for monitoring and protecting an electric power system. In one embodiment, a system may comprise line-mounted wireless current transformers to measure at least one parameter of an alternating current (AC), receive a synchronization signal at which to measure the AC, and send a message comprising the measured AC. The system may also comprise an intelligent electronic device (IED) to send the synchronization signal to and receive the messages from the line-mount wireless current transformers, determine whether a high-impedance fault (HiZ) exists between the line-mounted wireless current transformers, and implement a control action based on the existence of the HiZ fault.

Abstract: The present disclosure pertains to systems and methods for monitoring and protecting an electric power system. In one embodiment, a system may comprise line-mounted wireless current transformers to measure at least one parameter of an alternating current (AC), receive a synchronization signal at which to measure the AC, and send a message comprising the measured AC. The system may also comprise an intelligent electronic device (IED) to send the synchronization signal to and receive the messages from the line-mount wireless current transformers, determine whether a high-impedance fault (HiZ) exists between the line-mounted wireless current transformers, and implement a control action based on the existence of the HiZ fault.

Abstract: Detection and protection against electric power generator rotor turn-to-turn faults, rotor multi-point-to-ground faults, and rotor permanent magnet faults is provided herein. A fractional harmonic signal is used to determine the rotor fault condition. The fractional harmonic signal may be a fractional harmonic magnitude of the circulating current of one phase. The fractional harmonic may be a fractional harmonic magnitude of a neutral voltage. A tripping subsystem may issue a trip command based upon detection of a rotor turn-to-turn fault condition.

Abstract: Disclosed herein are systems for determining a broken conductor condition in a multiple-phase electric power delivery system. It has been observed that broken conductors pose a safety concern when occurring in the presence of people or vulnerable environmental conditions. Broken conductor conditions disclosed herein may be used to detect and trip the phase with the broken conductor, thus reducing or even eliminating the safety risk. Further, a distance to the opening may be determined.

Abstract: Electric power generator protection is secured by detecting wiring errors to an intelligent electronic device using terminal third voltages at the terminal (VT3) and third harmonic voltages at the neutral (VN3). When an angle between VT3 and VN3 is outside of an acceptable range, a wiring defect is detected, and certain protective operations are blocked. An alarm may be generated, facilitating personnel to identify and rectify the wiring defect. Wiring defects may further be detected when a torque calculated using VT3 and VN3 exceeds a predetermined error threshold. Security of protection elements is increased by detection of wiring defects that may have resulted in misoperation of the protection elements.

Abstract: The present disclosure relates to systems and methods for detecting transient high-torque events associated with rotating machinery in an electric power system. In one embodiment, a relay may include an electrical parameters module that receives a representation of a voltage and a current at a terminal of rotating machinery in an electric power system. A torque calculation module may continuously determine a calculated torque value for the rotating machinery using the representation of the voltage and the current at the terminal of the rotating machinery and compare each calculated torque value to a threshold. An action module may generate an alarm when the calculated torque value exceeds the threshold. A log module may generate a log comprising a peak of the calculated torque value and a time at which the peak torque value occurs.

Abstract: Protection devices prevent damage to synchronous generators during loss-of-field events. In various embodiments, a first protective element is associated with a first protection zone to protect a generator from a loss-of-field event at full load. A second protective element is associated with a second protection zone to prevent thermal overload during underexcited operation of the generator and to protect from loss-of-filed at light load. A third protective element associated with a third protection zone limits operation of the generator within the generator's specific steady-state stability limits. A fourth protective element is associated with a fourth protection zone to provide an alarm prior to operation of the second protective element.

Abstract: The present disclosure pertains to systems and methods for supervising protective elements in electric power systems. In one embodiment, a system may be configured to selectively enable a protective action an electric power system. The system may include a data acquisition subsystem receive a plurality of representations of electrical conditions associated with at least a portion of the electric power delivery system. An incremental quantities module may calculate incremental quantities from the plurality of representations. The system may be configured to detect an event, to determine an incremental quantities value during the event, and to determine a time-varying threshold. The incremental quantities value during the event may be compared with the time-varying threshold, and a protective action module may be enabled to implement a protective action when the value of the incremental quantities value during the event exceeds the time-varying threshold.

Abstract: Disclosed herein are a variety of systems and methods related to detection of a cross-country fault in an electrical power system. In one embodiment, a system consistent with the present disclosure may be configured to monitor electrical parameters in the electrical power system. The system may determine when a voltage magnitude of one phase exceeds a first voltage threshold. The one phase that exceeds the first voltage threshold may be identified as an un-faulted phase. The system may further be configured to determine that the voltage magnitude of the un-faulted phase exceeds a second threshold based on a zero-sequence voltage. The system may further be configured to determine that a phase angle between the un-faulted phase and the zero-sequence voltage is within a range. A protective action to clear the cross-country fault condition may be implemented upon identification of a cross-country fault.

Abstract: Systems and Methods are disclosed for providing measurement data redundancy to intelligent electronic devices (IEDs) in an electric power system, without additional redundant components. In various embodiments, a first measurement device obtains measurement data from a first portion of the electric power delivery system. A second measurement device obtains measurement data from a second portion of the electric power delivery system. A first IED monitors the first portion of the electric power delivery system based on measurement data associated with the first portion of the electric power delivery system, and a second IED monitors the second portion of the electric power delivery system based on measurement data associated with the second portion of the electric power delivery system.