A method and system are provided for transferring a load between a primary power source and a secondary power source. In accordance with the disclosure, a controller senses, via a sensor, an electrical signal providing power from the primary power source to the load. The controller also detects a non-conforming power event by determining that a parameter of the electrical signal is either more or less than a first threshold value. Responsive to the detection of the non-conforming power event, the controller determines a quantity of non-conforming power events that occur during a first time interval. The controller further can compares the determined quantity of non-conforming power events to a second threshold value. Responsive to the determined quantity of non-conforming power events being either greater or lesser than the second threshold value, the controller initiates a control signal, such as a control signal to initiate a load transfer.

Methods and systems for controlling a circuit designed to protect electrical equipment, in particular sensitive power grid equipment such as transformers, are disclosed. In particular, methods of local and remote control of operation of protection circuits are provided that allow for remote access to change an operational mode of such protection circuits, while ensuring that power grid equipment is protected locally regardless of any configuration instructions received from a remote or centralized facility. Override levels may be set to ensure power grid transformer protection, regardless of operational mode or remote instruction.

A method and system are provided for transferring a load between a primary power source and a secondary power source. In accordance with the disclosure, a controller senses, via a sensor, an electrical signal providing power from the primary power source to the load. The controller also detects a non-conforming power event by determining that a parameter of the electrical signal is either more or less than a first threshold value. Responsive to the detection of the non-conforming power event, the controller determines a quantity of non-conforming power events that occur during a first time interval. The controller further can compares the determined quantity of non-conforming power events to a second threshold value. Responsive to the determined quantity of non-conforming power events being either greater or lesser than the second threshold value, the controller initiates a control signal, such as a control signal to initiate a load transfer.

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.

Systems and method for detecting potentially harmful harmonic and direct current signals at a transformer are disclosed. One system includes a protection circuit electrically connected to a transformer neutral, the transformer electrically connected to a power grid, the protection circuit including a DC blocking component positioned between the transformer neutral and ground and one or more switches selectively actuated to form a path between the transformer neutral and ground in the event of unwanted DC current at the transformer neutral. The system also includes a control circuit electrically connected to the protection circuit and positioned to selectively actuate the switches based on observed conditions within the protection circuit. The system further includes a plurality of test connections disposed within the protection circuit and useable to test electrical properties of the protection circuit.

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.

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.

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 and system are provided for transferring a load between a primary power source and a secondary power source. In accordance with the disclosure, a controller senses, via a sensor, an electrical signal providing power from the primary power source to the load. The controller also detects a non-conforming power event by determining that a parameter of the electrical signal is either more or less than a first threshold value. Responsive to the detection of the non-conforming power event, the controller determines a quantity of non-conforming power events that occur during a first time interval. The controller further can compares the determined quantity of non-conforming power events to a second threshold value. Responsive to the determined quantity of non-conforming power events being either greater or lesser than the second threshold value, the controller initiates a control signal, such as a control signal to initiate a load transfer.