The invention relates to a novel approach for the protection of electrical circuits from ground faults and parallel and series arc faults in a fully solid-state circuit configuration. Solid-state circuits and methods of use are described that provide the key functions of low-voltage DC power supply, mains voltage and current sensing, fault detection processing and high voltage electronic switching.

A method for determining a location of a fault on a powerline, comprising: obtaining, using a measuring device at a measurement location on the powerline, time-dependent data of a voltage on the powerline and of a current through the powerline at the measurement location, wherein the time-dependent data is obtained during a time period after fault inception; removing fundamental frequency components from the time-dependent data; calculating, from the time-dependent data, a virtual fault inductance for at least two different potential fault locations, by inputting the time-dependent data into an equivalent circuit model, by means of time-domain calculations on the nonfundamental frequency waveform components; and deriving, from the virtual fault inductance for each of the potential fault locations, a location on the line at which the virtual fault inductance is substantially zero.

A system and method for controlling microgrids composed of inverter-based distributed generation (IBDG) units. This includes a method using multiple IBDGs to inject impedance-modulated harmonic currents during fault conditions, with each IBDG injecting a unique, differentiable harmonic (i.e., non-fundamental) order from neighboring IBDGs. The method also involves using an inverse time-harmonic-current characteristic to detect faults by locally measuring the harmonic currents injected by IBDGs. A harmonic directional overcurrent relay is also used for fault detection.

A system and method for controlling microgrids composed of inverter-based distributed generation (IBDG) units. This includes a method using multiple IBDGs to inject impedance-modulated harmonic currents during fault conditions, with each IBDG injecting a unique, differentiable harmonic (i.e., non-fundamental) order from neighboring IBDGs. The method also involves using an inverse time-harmonic-current characteristic to detect faults by locally measuring the harmonic currents injected by IBDGs. A harmonic directional overcurrent relay is also used for fault detection.

A DER (distributed energy resource) device includes a metrology module and a communications module. The metrology module monitors the output of the DER device and the communications module provides bidirectional communications across a communications network to control the DER device. The control of the DER devices may include commands to connect the DER device to the grid, to disconnect the DER device to the grid, to connect the DER device to the premises, or to adjust a power characteristic of the output of the DER device.

A DER (distributed energy resource) device includes a metrology module and a communications module. The metrology module monitors the output of the DER device and the communications module provides bidirectional communications across a communications network to control the DER device. The control of the DER devices may include commands to connect the DER device to the grid, to disconnect the DER device to the grid, to connect the DER device to the premises, or to adjust a power characteristic of the output of the DER device.

Effective feature set-based high impedance fault (HIF) detection is provided. Systems, methods and devices described herein present a systematic design of power feature extraction for HIF detection and classification. For example, power features associated with HIF events are extracted according to when a fault happens, how long it lasts, and the magnitude of the fault. Complementary power expert information is also integrated into feature pools. In another aspect, a ranking procedure is deployed in a feature pool for balancing information gain and complexity in order to avoid over-fitting of features. In aspects described herein, a logic-based HIF detector implements HIF feature extraction. To determine when an HIF occurs, the HIF detector calculates different quantities, such as active power and reactive power, based on a voltage and current time series, and uses the derivative of these quantities to tell when there is a potential change due to HIF.

Effective feature set-based high impedance fault (HIF) detection is provided. Systems, methods and devices described herein present a systematic design of power feature extraction for HIF detection and classification. For example, power features associated with HIF events are extracted according to when a fault happens, how long it lasts, and the magnitude of the fault. Complementary power expert information is also integrated into feature pools. In another aspect, a ranking procedure is deployed in a feature pool for balancing information gain and complexity in order to avoid over-fitting of features. In aspects described herein, a logic-based HIF detector implements HIF feature extraction. To determine when an HIF occurs, the HIF detector calculates different quantities, such as active power and reactive power, based on a voltage and current time series, and uses the derivative of these quantities to tell when there is a potential change due to HIF.

A network protector includes: a resettable switching apparatus configured to control an electrical connection between a first distribution transformer and a first electrical feeder of a secondary electrical distribution network; a sensor apparatus configured to sense one or more properties of electrical power in the first electrical feeder; and a controller configured to: analyze one or more of the sensed properties of the electrical power in the first electrical feeder to determine whether an error condition exists in the secondary electrical distribution network; and open the resettable switching apparatus if an error condition exists.

A detection scheme for temporary overvoltages and/or ground fault overvoltages in electric power systems is described. Current passing through a surge arrestor component of the power system is monitored. An algorithm for identifying one or more frequency components of the measured current signal is performed to screen out unwanted harmonics. In some embodiments, this is a frequency domain analysis. The frequency component(s) of the current signal is then compared to a calculated pickup current or pickup voltage of the system to determine if system protection steps should be undertaken.