A system for estimating faulted area in an electric distribution system. The system includes a database storing input data, a fault detection module to estimate, based on the input data, if a new faulted area estimation process is required, a condition estimation module to estimate condition of metered protective devices, un-metered protective devices, and metered devices (PMDs), an upstream to downstream module to assess condition of each metered protective device, un-metered protective device, and metered device (PMD), starting from a feeder circuit breaker towards feeder downstream, to estimate a tripped protective device and a last metered device upstream of a fault, and a downstream to upstream module configured to assess outaged electric loads or elements towards network upstream to find the common interrupting protective device.

A communication-based permissive protection method for protecting an electrical power distribution network from a fault. The network includes a power source, an electrical line and a plurality of fault interrupters, where the fault interrupters are operable to prevent current flow in response to the fault. The method includes detecting the fault by each fault interrupter that is between the fault and the power source, and sending a drop of voltage message from each fault interrupter that doesn't detect the fault, but does detect a drop of voltage as a result of the fault to its immediate upstream fault interrupter. The method opens the fault interrupter that both detects the fault and receives a drop of voltage message from all of the fault interrupters immediately downstream of that fault interrupter.

A photovoltaic power generation system includes an inverter, a controller, and at least two direct current branch circuits. The leakage current detection apparatus is configured to: detect a leakage current of the direct current branch circuit on which the leakage current detection apparatus is located and send the leakage current to the controller. The controller is further configured to: when the photovoltaic power generation system runs and a value of a leakage current of the direct current branch circuit exceeds a preset range, determine that an insulation fault occurs on the direct current branch circuit. The system can determine the direct current branch circuit on which the insulation fault occurs in the photovoltaic power generation system, so that measures are taken in time for the direct current branch circuit on which the insulation fault occurs, to eliminate a potential safety hazard.

A method can be used for phase selection using multi-terminal measurements of a transmission line of a power system. The method includes obtaining, using measurements from a plurality of terminals of the transmission line, delta differential current values ΔI.sub.diffA(t), ΔI.sub.diffB(t), ΔI.sub.diffC(t), at time t, between pre-fault differential current measurements and post-fault differential current measurements from all three phases (A, B, C) of the transmission line. The method also includes determining at least one of the phases to be faulty when the absolute value of the corresponding delta differential current value is larger than k times the minimum of all the absolute values IΔI.sub.diffA(t)|, |ΔI.sub.diffB(t)|, |ΔI.sub.diffC(t)| of the delta differential current values, where k>1 is a scale factor.

A system for estimating faulted area in an electric distribution system. The system includes a database storing input data, a fault detection module to estimate, based on the input data, if a new faulted area estimation process is required, a condition estimation module to estimate condition of metered protective devices, un-metered protective devices, and metered devices (PMDs), an upstream to downstream module to assess condition of each metered protective device, un-metered protective device, and metered device (PMD), starting from a feeder circuit breaker towards feeder downstream, to estimate a tripped protective device and a last metered device upstream of a fault, and a downstream to upstream module configured to assess outaged electric loads or elements towards network upstream to find the common interrupting protective device.

The present disclosure provides a protection assistance device of multiple circuit breakers in a low-voltage system, in which protection assistance in both directions from the upper side to the lower side or from the lower side to the upper side is possible, and the number of wires for protection assistance between multiple upper/lower circuit breakers can be minimized. The protection assistance device includes at least one upper low-voltage circuit breaker; at least one middle low-voltage circuit breaker; at least one lower low-voltage circuit breaker; and a communication line which makes a communication connection between the low-voltage circuit breakers, wherein the low-voltage circuit breakers comprise a control unit for, when a trip operation of automatically breaking a circuit is performed, transmitting a communication packet for reporting a trip operation state to at least one predetermined circuit breaker among the circuit breakers through the communication line.

A fault interrupting switching device that is part of a transformer in an underground residential power distribution circuit and provides fault isolation and restoration. The switching device includes a vacuum interrupter having a fixed terminal and a movable terminal, where the fixed terminal is electrically coupled to a transformer interface and the movable terminal is electrically coupled to a connector interface. A control rod is coupled to the movable terminal and an actuator assembly is coupled to the control rod and is operable to move the control rod to open and close the vacuum interrupter. An electronics assembly electrically is coupled to the movable terminal, and includes a high voltage capacitor and an energy storage capacitor, where the high voltage capacitor provides power to operate the actuator when the vacuum interrupter is open and the energy storage capacitor provides power to the electronics assembly when the vacuum interrupter is closed.

A switching device that is part of a transformer in an underground residential power distribution circuit and provides fault isolation and restoration. The switching device includes a transformer interface for coupling the device to the transformer and a connector interface for coupling the device to a connector. The device also includes a vacuum interrupter having a fixed terminal and a movable terminal, where the fixed terminal is electrically coupled to the connector interface and the movable terminal is electrically coupled to the transformer interface. A control rod is coupled to the movable terminal, an actuator assembly is coupled to the control rod and is operable to move the control rod to open and close the vacuum interrupter. A capacitor is electrically coupled to the fixed terminal, and provides an interface for power line communications signals, voltage sensing, help determine power flow direction and help determine the distance to a fault.

A switch assembly that is part of a transformer in an underground residential power distribution circuit and that provides fault isolation and restoration. The switch assembly includes first and second switching devices each having an outer housing, a transformer interface electrically coupled to the transformer, a connector interface electrically coupled to a first connector and a first vacuum interrupter having a fixed contact and a movable contact, where the fixed contact is electrically coupled to the connector interface and the movable contact is electrically coupled to the transformer interface. A control board controls the first and second switching devices, where the control board is responsive to voltage signals from capacitors in the first and second switching devices.

A method for isolating a fault in an underground power distribution network. The network includes a power line, a plurality of transformers electrically coupled to and positioned along the power line, a first recloser connected to one end of the power line and a second recloser connected to an opposite end of the power line, where each transformer includes an upstream switching device and a downstream switching device, and where power is provided to both ends of the power line through the first and second reclosers and one of the switching devices is a normally open switching device. The method includes detecting overcurrent by some of the switching devices, detecting loss of voltage by some of the switching devices and sending clear to close messages to some of the switching devices to open and close certain ones of the switching devices to isolate the fault.