Abstract: A power system for connecting a power source, an energy storage unit and a grid includes a power inverter, an energy storage power converter and a controller. The power inverter is electrically coupled to the power source through a DC bus and converts DC power from the DC bus to AC power output to the grid. The power converter is electrically coupled between the DC bus and the energy storage unit and stores power in the energy storage unit and discharges power from the energy storage unit. The controller controls the power converter to store excess power from the power source that cannot be output to the grid in the energy storage unit, and control the energy storage power converter to discharge power stored in the energy storage unit to the power inverter to output to the grid.

Abstract: A DC/DC converter system includes a bidirectional DC/DC converter converting between voltage levels at first and second ports and a control system for controlling the DC/DC converter. The bidirectional DC/DC converter includes a first conversion stage connected to the first port and a second conversion stage interfaced with the first conversion stage and connected to the second port. The control system includes outer and inner control loops. The outer control loop compares a command for one of a voltage level, a current level or power at one of the first and second ports to an actual value of voltage level, current level or power level and outputs an interface current command based on the comparison. The inner control loop compares the interface current command to an actual interface current at an interface of the first and second conversion stages, and controls a switching signal duty value based on the comparison.

Abstract: A power system for connecting a power source, an energy storage unit and a grid includes a power inverter, an energy storage power converter and a controller. The power inverter is electrically coupled to the power source through a DC bus and converts DC power from the DC bus to AC power output to the grid. The power converter is electrically coupled between the DC bus and the energy storage unit and stores power in the energy storage unit and discharges power from the energy storage unit. The controller controls the power converter to store excess power from the power source that cannot be output to the grid in the energy storage unit, and control the energy storage power converter to discharge power stored in the energy storage unit to the power inverter to output to the grid.

Abstract: A DC/DC converter system includes a bidirectional DC/DC converter converting between voltage levels at first and second ports and a control system for controlling the DC/DC converter. The bidirectional DC/DC converter includes a first conversion stage connected to the first port and a second conversion stage interfaced with the first conversion stage and connected to the second port. The control system includes outer and inner control loops. The outer control loop compares a command for one of a voltage level, a current level or power at one of the first and second ports to an actual value of voltage level, current level or power level and outputs an interface current command based on the comparison. The inner control loop compares the interface current command to an actual interface current at an interface of the first and second conversion stages, and controls a switching signal duty value based on the comparison.

Abstract: An energy storage system for direct DC coupling includes a power source electrically connected to a first node, a power converter coupled to the first node, an energy storage unit coupled to the first node through direct DC coupling, and a control system. The power converter controls the output voltage of the power source under the control of the control system. The energy storage unit draws energy from the power source or the bus when charging and supplies energy to the bus when discharging. A main switch is coupled between the first node and the energy storage unit. The control system is configure to control the power converter to adjust the output voltage to the energy storage unit voltage, control the main switch to electrically connect the energy storage unit to the first node, and control the main switch to electrically disconnect the energy storage unit from the first node.

Abstract: An energy storage system for renewable energy applications includes a renewable energy source, a bidirectional inverter connected an AC bus and a DC bus, an energy storage unit connected to the bidirectional DC/DC converter, and a control system comprising one or more controllers coupled to the bidirectional inverter and the bidirectional DC/DC converter. The bidirectional inverter is connected to the renewable energy source and a bidirectional DC/DC converter through the DC bus. The control system is configured to facilitate the operation of the bidirectional DC/DC converter and the bidirectional inverter. The energy storage system both stores energy from the renewable energy source and a utility grid, and also supplies power to the utility grid. The energy storage system is utilized in a method for supporting frequency regulation of a utility grid and a method for controlling an output power ramp rate for a renewable energy storage system.

Abstract: A power system having a plurality of power converters coupled together at a point of common coupling (PCC). The power converters are coupled to a load and provide a combined power converter output to the load. A switch is coupled in series between the PCC and an external grid. When the switch is closed, the power system is in a grid-tied configuration and when the switch is open, the power system is in a microgrid configuration. A control system coupled to the power converters enables the switch to open and close in response to a signal received from one or more sensors monitoring the external grid, enables the power converters to operate in a current control mode when the switch is closed, and transitions the power converters from grid-tied mode to microgrid mode and synchronize the power converters such that the converters share the load.

Abstract: An energy system for renewable energy applications includes a renewable energy source, a bidirectional inverter connected an AC bus and a DC bus, an energy storage unit connected to the bidirectional DC/DC converter, and a control system comprising one or more controllers coupled to the bidirectional inverter and the bidirectional DC/DC converter. The bidirectional inverter is connected to the renewable energy source and a bidirectional DC/DC converter through the DC bus. The system is configured to capture low power of a photovoltaic (PV) array, energy typically lost to inverter clipping, and through the utilization of ramp rate control.

Abstract: A power system for power conversion between at least one power source and a grid is disclosed. The power system includes a power converter having a plurality of semiconductor switches, configured to adapt a power supply to a desired output; and a controller for controlling the power converter in an active mode and an active standby mode, the controller configured to: determine to enter into the active mode or the active standby mode; based on the active mode or the active standby mode is determined, control the power converter to be in a gating state with the grid or to be in a non-gating state with the grid.

Abstract: A power system and method for performing a blackstart on a microgrid. The power system includes at least a first power converter and a second power converter. The first power converter comprises a first controller having a plurality of startup sequences for performing the blackstart. The second power converter is electrically coupled to the first power converter at a point of common coupling. During the blackstart, the first controller is configured to select and perform one of the plurality of startup sequences according to a point at which the second power converter is within the second power converter's startup sequence during the blackstart. The first controller selects the one of the plurality of startup sequences according to a microgrid voltage at the point of common coupling.

Abstract: A power system having a plurality of power converters coupled together at a point of common coupling (PCC). The power converters are coupled to a load and provide a combined power converter output to the load. A switch is coupled in series between the PCC and an external grid. When the switch is closed, the power system is in a grid-tied configuration and when the switch is open, the power system is in a microgrid configuration. A control system coupled to the power converters enables the switch to open and close in response to a signal received from one or more sensors monitoring the external grid, enables the power converters to operate in a current control mode when the switch is closed, and transitions the power converters from grid-tied mode to microgrid mode and synchronize the power converters such that the converters share the load.

Abstract: A power system having a plurality of operating modes including an active mode and an active standby mode includes a power converter and a controller the power converter is configured to adapt a power supply to a desired output, and the power converter includes a plurality of semiconductor switches that receive a gating signal when the power system is in the active mode such that the power converter is in a gating state. The controller controls the power converter in the active mode and the active standby mode, and the controller is configured to: while the power converter is synchronized to the grid, determine whether the power system should enter into the active standby mode in which the power converter is in a non-gating state; when it is determined the power system should enter into the active standby mode, control the power converter to be in a non-gating state such that the power system is in the active standby mode.

Abstract: The present invention provides a novel electrical power system for micro-grid and distributed generation systems. The invention provides a common, singular Alternating Current (AC) electrical port for multiple Direct Current (DC) generation sources, DC loads and DC electrical energy storage sources. The invention balances the flow of energy through said storage, load and generation sources to provide a constant voltage and frequency to a micro-grid or a regulated real and reactive power component to an electric utility grid. A centralized controller is capable of commanding bi-directional current flow on each DC port in order to maintain an optimum State of Charge such that the storage medium can service both the utility grid and a micro-grid and dynamically transfer between the two operational modes.