A method and system of providing a power supply to a load (108) using a micro-grid (122) and an electrical grid (102) without interrupting a power supply to the load (108) during a power failure and restoration of the electrical grid (102). A non-grid AC sine wave is synchronized to a grid AC sine wave at the AC to AC synchronization circuit (120) when the electrical grid (102) power supply is restored, without turning OFF the DC to the AC inverter (118) by performing synchronization of the non-grid AC sinewave to match the grid AC sine wave over a number of cycles to make the non-grid AC sine wave compatible with the grid power supply while the power supply generated from the non-grid sources (116) remains uninterrupted and the voltage is in the predetermined threshold range for providing to the load (108).

In one aspect, a modular static transfer switch is provided. The module static transfer switch includes an output configured to couple to a load, a first input configured to couple to a first power source, and a second input configured to couple to a second power source. The modular static transfer switch further includes a plurality of sold-state switch modules each comprising at least one solid-state switch. A first plurality of the solid-state switch modules are coupled in parallel between the first input and the output, each configured to selectively couple the first power source to the output using the at least one solid-state switch. A second plurality of the solid-state switch modules are coupled in parallel between the second input and the output, each configured to selectively couple the second power source to the output using the at least one solid-state switch.

An off-line uninterruptible power system and two line-interactive uninterruptible power systems are provided. The off-line uninterruptible power system and one of the line-interactive uninterruptible power systems additionally adopt a transformer for supplying an AC output, with lower voltage level than a rated output voltage, to at least one electrical device (especially those with resistive load characteristic). The other line-interactive uninterruptible power system controls its automatic voltage regulating circuit to supply an AC output, with lower voltage level than a rated output voltage, to at least one electrical device (especially those with resistive load characteristic).

The present disclosure provides a photovoltaic (PV) disconnect device used in an electrical system. The PV disconnect device includes a relay component electrically coupled to a feed circuit of a backup PV power generation system and a connector port electrically coupled to an energy control system. The PV disconnect device includes a sensor circuit to measure at least one of a voltage, a current, and a current frequency of the feed circuit of the backup PV power generation system. The PV disconnect device includes a controller operatively coupled to the relay component, the sensor circuit, and the connector port. The controller receives and processes the voltage, the current, and the current frequency measurements. The controller selectively actuates the relay component based on the processed voltage, current, and current frequency measurements.

An uninterruptible power system includes a power conversion apparatus, a switch unit and a control apparatus. The switch unit outputs a mains voltage in a line mode, and output an alternating conversion voltage in a battery mode. The control apparatus is configured to generate a base triangular wave signal according to the mains voltage. When the uninterruptible power system is in a battery mode and the control apparatus detects the regeneration of the mains voltage, the control apparatus is configured to determine whether a cross-over value of the base triangular wave signal is within a predetermined range when the mains voltage is at a zero-cross point. The control apparatus is configured to control the switch unit to output the mains voltage instead of the alternating conversion voltage when the cross-over value of the base triangular wave signal is within the predetermined range.

Various disclosed embodiments include illustrative controller units, systems, vehicles, and methods. In an illustrative embodiment, an energy management control unit includes a communication device, a processor, and non-transitory computer-readable media having computer-executable instructions. The instructions cause the processor to receive a grid energy supply value and determine a grid energy supply outage responsive to the received grid energy supply value. Responsive to the determined grid energy supply outage, the instructions cause the processor to receive plug-in status of a removable direct current (DC) energy storage device, receive first available power information of the removable DC energy storage device responsive to the plug-in status indicating available, receive active load power usage information responsive to the first available power information being greater than a minimum reserve threshold, and shed a first electrical load responsive to the determined active load power usage information being greater than a first shedding threshold.

According to one aspect, embodiments of the invention provide an uninterruptible power supply (UPS) system comprising an input configured to receive input AC power, an output configured to provide output AC power to a load, a DC power source coupled to a DC bus, an inverter having an input coupled to the DC bus and an output coupled to the output of the UPS system, the inverter configured to receive DC power at the input from the DC bus and provide AC power having a voltage to the output, and a controller coupled to the output of the inverter and configured to operate the inverter based on an average voltage of the AC power at the output of the inverter.

A controller circuit for a PV module includes a receiver circuit and a mode control and power conversion circuit. The receiver circuit receives a first signal from a transmitter circuit and changes a second signal from a first state to a second state responsive to the first signal. The mode control and power conversion circuit receives a DC voltage from a string of PV cells, receives the second signal from the receiver circuit, switches from a first mode to a second mode in response to the second signal being in the second state, converts the DC string voltage to a standby voltage in the second mode, and provides the standby voltage to DC power lines. The standby voltage is less than an operating voltage provided by the mode control and power conversion circuit in the first mode.

A power generation method includes providing power from a first DC power source to a load, while a second DC power source is electrically disconnected from the load, electrically connecting the second DC power source to the load and providing power from the second DC power source to the load if an output voltage from the first DC power source drops below a threshold voltage and an output voltage from the second DC power source is not below the threshold voltage, and electrically disconnecting the first DC power source from the load if an output current of the first DC power source is below a threshold current.

A power supply control device includes: a first system configured to supply electric power from a first power supply to a first load group; a second system configured to supply electric power from a second power supply to a second load group; a plurality of load switches configured to switch an electric power supply to each load of the first load group and the second load group; and a control unit configured to control the plurality of load switches such that electric power is supplied from the second power supply to a backup load included in at least one of the first load group and the second load group in a predetermined backup state, wherein the control unit detects a state of charge of the second power supply, and increases, in the predetermined backup state, number of the load switches to be connected as the state of charge is higher.