A method and system of controlling a power converter coupled between one of a motor drive inverter and a grid-tie inverter within an electric grid. The method comprises operating the power converter in a first PLL control mode that establishes a state of synchronization with the electric grid, detecting a grid disturbance voltage dip event; keeping the power converter synchronized and preserving charge of a set of dc-link capacitors, switching from the first PLL control mode to a second PLL control mode of operation of the power converter to obtain fast re-synchronization after dip period ends, and reverting to operation in the first PLL control mode upon re-establishing of the state of synchronization.

A method and system of controlling a power converter coupled between one of a motor drive inverter and a grid-tie inverter within an electric grid. The method comprises operating the power converter in a first PLL control mode that establishes a state of synchronization with the electric grid, detecting a grid disturbance voltage dip event; keeping the power converter synchronized and preserving charge of a set of dc-link capacitors, switching from the first PLL control mode to a second PLL control mode of operation of the power converter to obtain fast re-synchronization after dip period ends, and reverting to operation in the first PLL control mode upon re-establishing of the state of synchronization.

A power converter includes: an inverter converting DC power to AC power and outputting the AC power to first and second voltage terminals of a connection terminal unit; and switches RC. The switches RC include a first protection switch provided to a first line connecting the inverter and the first voltage terminal together, a second protection switch provided to a second line connecting the inverter and the second voltage terminal together, and a voltage switch connected in series between the second line and a neutral terminal. A load connection terminal is connected to a line connecting between the first line and the voltage switch.

A power converter includes: an inverter converting DC power to AC power and outputting the AC power to first and second voltage terminals of a connection terminal unit; and switches RC. The switches RC include a first protection switch provided to a first line connecting the inverter and the first voltage terminal together, a second protection switch provided to a second line connecting the inverter and the second voltage terminal together, and a voltage switch connected in series between the second line and a neutral terminal. A load connection terminal is connected to a line connecting between the first line and the voltage switch.

A Hamiltonian surface shaping power flow control (HSSPFC) method is used to analyze the meta-stability and adjust pulsed power loads on a DC electric power distribution network. Pulsed power loads are nonlinear, time-variant systems that cause nonlinear limit-cycles. During the on periods of a pulsed load, the system can be in an unstable state and is damped back to stability during the off state of the load. Therefore, over the entire period of the pulse the system may only be assessed as meta-stable. As shown through simulation, HIL and hardware results, the HSSPFC method is more accurate than the other small-signal approaches, such as Eigenvalues, Nyquist, and Floquet theory, and can reveal important details about the transient responses and performance.

A Hamiltonian surface shaping power flow control (HSSPFC) method is used to analyze the meta-stability and adjust pulsed power loads on a DC electric power distribution network. Pulsed power loads are nonlinear, time-variant systems that cause nonlinear limit-cycles. During the on periods of a pulsed load, the system can be in an unstable state and is damped back to stability during the off state of the load. Therefore, over the entire period of the pulse the system may only be assessed as meta-stable. As shown through simulation, HIL and hardware results, the HSSPFC method is more accurate than the other small-signal approaches, such as Eigenvalues, Nyquist, and Floquet theory, and can reveal important details about the transient responses and performance.