A micro grid system comprises a secondary energy source and a power controller. The secondary energy source is associated with a micro grid that includes a fixed or mobile facility, and the secondary energy source is configured to generate first DC power signal. The power controller is in communication with the secondary energy source and an electric grid, and configured to receive first AC power signal from the electric grid and the first DC power signal from the secondary energy source and output a second AC power signal to loads in communication with the power controller. The power controller comprises an AC to DC frequency converter configured to change frequency and/or voltage of the second AC power signal, a processor, and a memory configured to store instructions that, when executed, cause the processor to control the frequency converter to change the frequency and/or voltage of the second AC power signal.

A micro grid system comprises a secondary energy source and a power controller. The secondary energy source is associated with a micro grid that includes a fixed or mobile facility, and the secondary energy source is configured to generate first DC power signal. The power controller is in communication with the secondary energy source and an electric grid, and configured to receive first AC power signal from the electric grid and the first DC power signal from the secondary energy source and output a second AC power signal to loads in communication with the power controller. The power controller comprises an AC to DC frequency converter configured to change frequency and/or voltage of the second AC power signal, a processor, and a memory configured to store instructions that, when executed, cause the processor to control the frequency converter to change the frequency and/or voltage of the second AC power signal.

A high voltage direct current (HVDC) transmission system is provided. The high voltage direct current (HVDC) transmission system includes a rectifier converting alternating current (AC) power into DC power; an inverter converting the DC power into the AC power; DC transmission lines W1 and W2 transmitting the DC power obtained from the rectifier through conversion to the inverter; a first active power measurement unit measuring first active power input to the rectifier; a second active power measurement unit measuring second active power output from the inverter; and a first control unit controlling the operations of the rectifier and the inverter based on the first active power measured and the second active power measured, wherein the first control unit senses oscillation generated in the HVDC transmission system and generates a control signal for damping the sensed oscillation to control one or more of the rectifier and the inverter.

A control system for an electric motor, the control system comprising a first control device arranged to control an operation of a first component of the electric motor; a second control device arranged to control an operation of a second component of the electric motor, wherein the first control device is arranged to transmit to the second control device a first signal for indicating the transmission of data over a first communication link to the second control device, wherein the second control device is arranged to use the timing of the first signal to synchronize the operation of the second component with the operation of the first component.

A micro grid system comprises an adapter, a power controller, and secondary energy source. The adapter is in communication with an electric grid and configured to connect and disconnect a connection between the electric grid and a micro grid. The power controller is in communication with the adapter and configured to receive first AC power from the electric grid via the adapter, obtain grid information, and control the adapter to connect and disconnect the connection between the electric grid and the micro grid. The power controller controls the adapter to disconnect the connection in response to determining that the electric grid is abnormal based on the grid information. The secondary energy source is in communication with the power controller and is configured to generate DC power and to supply the DC power to the power controller.

A micro grid system comprises an adapter, a power controller, and secondary energy source. The adapter is in communication with an electric grid and configured to connect and disconnect a connection between the electric grid and a micro grid. The power controller is in communication with the adapter and configured to receive first AC power from the electric grid via the adapter, obtain grid information, and control the adapter to connect and disconnect the connection between the electric grid and the micro grid. The power controller controls the adapter to disconnect the connection in response to determining that the electric grid is abnormal based on the grid information. The secondary energy source is in communication with the power controller and is configured to generate DC power and to supply the DC power to the power controller.

A micro grid system comprises an adapter, a power controller, and secondary energy source. The adapter is in communication with an electric grid and configured to connect and disconnect a connection between the electric grid and a micro grid. The power controller is in communication with the adapter and configured to receive first AC power from the electric grid via the adapter, obtain grid information, and control the adapter to connect and disconnect the connection between the electric grid and the micro grid. The power controller controls the adapter to disconnect the connection in response to determining that the electric grid is abnormal based on the grid information. The secondary energy source is in communication with the power controller and is configured to generate DC power and to supply the DC power to the power controller.

A micro grid system comprises an adapter, a power controller, and secondary energy source. The adapter is in communication with an electric grid and configured to connect and disconnect a connection between the electric grid and a micro grid. The power controller is in communication with the adapter and configured to receive first AC power from the electric grid via the adapter, obtain grid information, and control the adapter to connect and disconnect the connection between the electric grid and the micro grid. The power controller controls the adapter to disconnect the connection in response to determining that the electric grid is abnormal based on the grid information. The secondary energy source is in communication with the power controller and is configured to generate DC power and to supply the DC power to the power controller.

A micro grid system comprises a secondary energy source and a power controller. The secondary energy source is associated with a micro grid that includes a fixed or mobile facility, and the secondary energy source is configured to generate first DC power signal. The power controller is in communication with the secondary energy source and an electric grid, and configured to receive first AC power signal from the electric grid and the first DC power signal from the secondary energy source and output a second AC power signal to loads in communication with the power controller. The power controller comprises an AC to DC frequency converter configured to change frequency and/or voltage of the second AC power signal, a processor, and a memory configured to store instructions that, when executed, cause the processor to control the frequency converter to change the frequency and/or voltage of the second AC power signal.

A micro grid system comprises a secondary energy source and a power controller. The secondary energy source is associated with a micro grid that includes a fixed or mobile facility, and the secondary energy source is configured to generate first DC power signal. The power controller is in communication with the secondary energy source and an electric grid, and configured to receive first AC power signal from the electric grid and the first DC power signal from the secondary energy source and output a second AC power signal to loads in communication with the power controller. The power controller comprises an AC to DC frequency converter configured to change frequency and/or voltage of the second AC power signal, a processor, and a memory configured to store instructions that, when executed, cause the processor to control the frequency converter to change the frequency and/or voltage of the second AC power signal.