A method of detecting a serial arc fault in a DC-power circuit includes injecting an RF-signal with a narrow band-width into the DC-power circuit and measuring a response signal related to the injected RF-signal in the DC-power circuit. The method further includes determining a time derivative of the response signal, analyzing the time derivative, and signaling an occurrence of a serial arc fault in the power circuit based on the results of the analysis. A system for detecting an arc fault is configured to perform a method as described before.

An arc fault detection system samples a high frequency signal on a power line sequentially at different frequency regions according to a frequency hopping sequence, which is repeated a number of times over a predefined period. The different frequency regions include at least one region with a carrier for power line communication on the power line and at least one region without a carrier for power line communication on the power line. The system obtains energy measurements for each frequency region based on the sampled signals, computes an energy level for each frequency region based on the measurements for each region, and assigns a binary value to each region according to the corresponding energy level. The binary value represents a presence or absence of signal content in the frequency region. The system determines a presence or absence of an arc fault based on the binary values for the frequency regions.

Line-mounted devices for determining fault magnitude in an electric power delivery system even under current-transformer (CT) saturation are disclosed herein. Fault magnitude is calculated using unsaturated regions of a current waveform captured by the line-mounted device. The method of determining the unsaturated regions is computationally efficient. Fictitious peaks are removed, and the unsaturated regions are determined based on fractions of the valid peaks. Fault current magnitude is calculated using sample values in the unsaturated regions.

A method for detecting a tripping of a disconnection unit in an electrical enclosure, the electrical enclosure including at least one disconnection unit for disconnecting electric current and at least one switching unit for switching the electric current, the method including a learning phase configured to generate decision-making categories associated with an acoustic signature of the tripping of the at least one disconnection unit, and a phase of detecting the tripping of the disconnection unit, including: acquiring a unit noise signal generated by at least one of the disconnection units for disconnecting the electric current or at least one switching unit for switching the electric current, and comparing the unit noise signal with the decision-making categories in order to detect whether the unit noise signal corresponds to the tripping of the disconnection unit.

Disclosed a method and system for fault location and protection of Microgrids which are operated under islanded mode by being disconnected from distribution systems under large disturbance or disaster scenarios. The disclosed method is invented to meet the protection needs for disconnected ungrounded microgrids without appropriate protection systems that are usually installed only at distribution substations. Moreover, the disclosed protection method or scheme is targeted at inverter-dominated microgrids in which fault current limiters are installed to protect inverters introduced by the increasing penetration of inverter-based distributed generators (IBDGs). Based on transient analysis and dynamic simulation of islanded ungrounded microgrids during different types of faults, it is realized that of the first terminal and second terminal sensors of the branch different types of faults can be effectively detected based on sequent components of currents flowed through terminals at faulted branches or sections, even with multiple IBGDs deployed in the Microgrids under different control strategies. The phase angle differences of zero sequence currents, and magnitude differences of negative sequence currents, and sign changes of phase currents are used to locate and protect against unsymmetrical and symmetrical faults within the islanded microgrids with lower fault currents, respectively.

A method and device for timing in time-varying distance protection based on multiple lines of a tower. The method includes: collecting an instantaneous current value at a time-varying distance protection installation location in the multiple lines of the tower, and acquiring preset parameters; calculating, according to the preset parameters and a multi-line ranging model, a multi-line ranging result; calculating, according to the preset parameters, the multi-line ranging result, and an adaptive calculation model, time of a section-II distance protection action and final time of a section-III distance protection action; and determining, according to the instantaneous current value, the preset parameters, and a cross-line failure auxiliary criterion model, final time of the section-II distance protection action.

An anomaly detection device that detects an anomaly in an object, the anomaly detection device includes: an analyzer that performs frequency analysis of sensing data obtained from a sensor that senses a physical quantity of the object; and a determiner that determines whether an anomaly is occurring in the object based on an output result output from a trained model by inputting frequency analysis data of the sensing data obtained from the sensor to the trained model that has been trained based on at least one of frequency analysis data of sensing data of the physical quantity obtained when the object is in a normal state or frequency analysis data of sensing data of the physical quantity obtained when the object is in an anomalous state.

Output circuit devices for use in electric power systems may include a first output subsystem for transmitting a first signal output via an output port to a component of the electric power system, an input subsystem for receiving and monitoring the first signal output transmitted by the first output subsystem, and a second output subsystem for transmitting another signal output to the component of the electric power system. The second output subsystem is to transmit the signal output in response to an indication from the input subsystem. Intelligent electronic devices (IEDs) and associated methods may include one or more output circuit devices.

Disclosed a method and system for fault location and protection of Microgrids which are operated under islanded mode by being disconnected from distribution systems under large disturbance or disaster scenarios. The disclosed method is invented to meet the protection needs for disconnected ungrounded microgrids without appropriate protection systems that are usually installed only at distribution substations. Moreover, the disclosed protection method or scheme is targeted at inverter-dominated microgrids in which fault current limiters are installed to protect inverters introduced by the increasing penetration of inverter-based distributed generators (IBDGs). Based on transient analysis and dynamic simulation of islanded ungrounded microgrids during different types of faults, it is realized that of the first terminal and second terminal sensors of the branch different types of faults can be effectively detected based on sequent components of currents flowed through terminals at faulted branches or sections, even with multiple IBGDs deployed in the Microgrids under different control strategies. The phase angle differences of zero sequence currents, and magnitude differences of negative sequence currents, and sign changes of phase currents are used to locate and protect against unsymmetrical and symmetrical faults within the islanded microgrids with lower fault currents, respectively.

A personal electronic device can include a main printed circuit board having disposed thereon a processing unit, one or more auxiliary circuits coupled to the main printed circuit board by one or more corresponding flexible printed circuits and one or more temperature sensors disposed on one of the flexible printed circuits. A processing unit of the portable electronic device can be configured to monitor the one or more temperature sensors, provide a warning in response to a monitored temperature exceeding a first threshold, and to cause a shutdown of at least a portion of the personal electronic device in response to the monitored temperature exceeding a second threshold. The temperature sensors can be negative temperature coefficient resistors.