Distance protection of electric power delivery systems are disclosed herein where a fault within a zone of protection is detected using time-domain fault detection supervised by frequency-domain fault detection. The distance fault detection may be asserted when the real or imaginary parts of the time-domain operating and polarizing quantities are both positive or both negative and an angle between the frequency domain operating and polarizing quantities is within a predetermined range. Additional security may be provided using a level check, a sign consistency check, or a disturbance detector.

A secure distance protection for electric power delivery systems under transient conditions is disclosed herein. Upon detection of a transient condition, additional security is added to a distance protection element before a protective action is taken. The transient condition may be detected when an angle of advancement of an operating signal is outside of a predetermined threshold. An unsecure condition may also be detected before applying additional security. The unsecure condition may be detected based on an estimation of a fault within a close-in zone and a voltage magnitude falling below a threshold.

A system for managing short-circuits in an aircraft meshed electrical energy distribution network, comprising nodes connected to one another by inter-node links forming a mesh of the network. A system node comprises a switch, a current limiter, circuitry elements to measure the current intensity circulating on the link and circuitry elements to measure a voltage drop on the link, and a control unit configured to acquire a link current measurement, compare the measurement with a predetermined current threshold and, if the measurement exceeds this threshold, command the current limiter to limit the link current, acquire a link voltage drop measurement, determine a time associated with the value of the voltage drop and check whether the voltage drop is still present after a time period equal to the time obtained, and if the voltage drop is still present then, command the opening of the switch corresponding to this link.

A system for managing short-circuits in an aircraft meshed electrical energy distribution network, comprising nodes connected to one another by inter-node links forming a mesh of the network. A system node comprises a switch, a current limiter, circuitry elements to measure the current intensity circulating on the link and circuitry elements to measure a voltage drop on the link, and a control unit configured to acquire a link current measurement, compare the measurement with a predetermined current threshold and, if the measurement exceeds this threshold, command the current limiter to limit the link current, acquire a link voltage drop measurement, determine a time associated with the value of the voltage drop and check whether the voltage drop is still present after a time period equal to the time obtained, and if the voltage drop is still present then, command the opening of the switch corresponding to this link.

A secure distance protection for electric power delivery systems under transient conditions is disclosed herein. Upon detection of a transient condition, additional security is added to a distance protection element before a protective action is taken. The transient condition may be detected when an angle of advancement of an operating signal is outside of a predetermined threshold. An unsecure condition may also be detected before applying additional security. The unsecure condition may be detected based on an estimation of a fault within a close-in zone and a voltage magnitude falling below a threshold.

Distance protection of electric power delivery systems are disclosed herein where a fault within a zone of protection is detected using time-domain fault detection supervised by frequency-domain fault detection. The distance fault detection may be asserted when the real or imaginary parts of the time-domain operating and polarizing quantities are both positive or both negative and an angle between the frequency domain operating and polarizing quantities is within a predetermined range. Additional security may be provided using a level check, a sign consistency check, or a disturbance detector.

Method for the directional determination of an earth fault in an electric power distribution network, characterised in that it comprises the steps of: Determining (E2) a residual current phasor and a residual voltage phasor, Determining (E3) an active current, Comparing (E7) the residual voltage phasor module with a threshold (SVR), and as long as the residual voltage phasor module remains higher than the threshold (SVR) or a fraction of the threshold (SVR), and for a predetermined number of iterations: Determining (E9, E12) the integral of the active current and of its sign, Determining the number of times when the residual current phasor module is greater than a predetermined threshold (SIR), during the predetermined number of iterations, If the residual current phasor module is greater than the predetermined threshold (SIR) at least one time, during the predetermined number of iterations, Determining (E16) the location upstream or downstream of the fault according to the number of times when the sign of the integral of the active current was positive or negative during the predetermined number of iterations.

A method and system is provided for locating a fault in a mixed power transmission line. The method is implemented by an Intelligent Electronic Device (IED) of the mixed line. The IED detects a travelling wave from one or more signals received from one or more measurement equipment. Thereafter, the IED identifies a line section with the fault, and generates two or more estimates for the location of the fault based on a time difference between arrival of two peaks of the travelling wave, a velocity of propagation of the travelling wave in the line section identified with the fault, and a length of one or more line sections. The IED determines the location of the fault based on a comparison of each estimate with a threshold, wherein the threshold is estimated based on the one or more signals, equivalent source impedance of each source and total line impedance.

Systems and methods for identifying faulted segment(s) in a multiphase power network may include receiving a current measurement that was measured during a fault, obtaining a set of equivalent sequence impedances for the segments, building a set of sequence bus impedance matrices, selecting a segment, calculating coefficients for the segment based on the set of equivalent sequence impedances for the segment and the sequence bus impedance matrices, calculating an estimated per unit fault distance for the segment based at least partially on the current measurement and the coefficients, identifying the segment as a potentially faulted segment if the estimated fault distance for the segment is between about zero and about one, and repeating for each of the segments the calculating coefficients, calculating an estimated per unit fault distance, and identifying as a potentially faulted segment if the estimated fault distance for the segment is between about zero and about one.

A power converter includes first and second arms, each having switching elements, and performs power conversion between a DC system and an AC system. An AC circuit breaker and a current control circuit are connected in series between the AC system and the power converter. The current control circuit includes a current-limiting resistor and a disconnector connected in parallel. A controller instructs a disconnector to close after an initial charge of the power converter and opens the AC circuit breaker when an impedance of a line between a first node located on a first end side of the current control circuit and a second node located on a second end side of the current control circuit is not less than a first threshold and an accumulated value of a current flowing through the current control circuit within a certain period of time is not less than a second threshold.