Abstract: The disclosure discloses a dynamic stability analysis method and device for a linear time-periodic (LTP) system. The method includes the following steps. Calculate the Q matrix corresponding to the LTP system, and use the eigenvalue of Q matrix whose real part is positive as an instability eigenvalue. Each instability eigenvalue is subjected to the following steps. (S1) the state space model is transformed into the infinite-order harmonic state space (HSS) model, and the truncation order m of HSS model is initialized to 1. (S2) after m-th order truncation of the HSS model, its eigenvalue thereof is calculated. If the real part of the eigenvalue of HSS model is not the same as the real part of the instability eigenvalue, m is updated, and step (S2) is performed again; otherwise, modal participation factor analysis is performed to obtain the state variables that dominate the system instability.

Abstract: An AC excitation synchronous condenser and a control method, an AC-excitation induction machine, a full-controlled AC excitation converter, a grid-side converter and a controller. The AC-excitation induction machine is the core power converting device, and its stator and rotor windings are AC windings with terminals. The controller is configured to control the full-controlled AC excitation converter to perform excitation and speed regulation on the AC-excitation induction machine and also control the grid-side converter to ensure the excitation capability of the full-controlled AC excitation converter, so that support and regulation of the active power and reactive power are achieved.

Abstract: An AC excitation synchronous condenser and a control method, an AC-excitation induction machine, a full-controlled AC excitation converter, a grid-side converter and a controller. The AC-excitation induction machine is the core power converting device, and its stator and rotor windings are AC windings with terminals. The controller is configured to control the full-controlled AC excitation converter to perform excitation and speed regulation on the AC-excitation induction machine and also control the grid-side converter to ensure the excitation capability of the full-controlled AC excitation converter, so that support and regulation of the active power and reactive power are achieved.

Abstract: A power supply system, including an energy module, a controlled object, an active power controller, and an inertia-synchronization controller. The input end of the energy module operates to acquire external energy, a first output end of the energy module is connected to the controlled object, and the energy module operates to transform the acquired external energy into electric energy, or transform electric energy into electric energy having a different frequency therefrom. The input end of the active power controller is connected to a second output end of the energy module, the output end of the active power controller is connected to the controlled object, and the active power controller operates to control output active power of the controlled object. The input end of the inertia-synchronization controller operates to connect with an AC system. The output end of the inertia-synchronization controller is connected to the controlled object.

Abstract: Provided is an operating method of a full-bridge sub-module (FBSM)-based modular multilevel converter for HVDC transmission with AC-side voltage boosting. The peak value of the AC-side voltage is increased under a constant DC-link voltage by using FBSM's negative output voltage under steady state, wherein keeping the semiconductor's current rating constant during AC-side voltage boosting is in favor of reducing converter cost by decreasing energy interaction between the upper and lower arms in a leg, and further capacitance value of FBSM's capacitor under a constant capacitor voltage ripple, keeping the RMS value of AC-side current constant during AC-side voltage boosting can effectively improve transmission capacity of the converter while reducing converter cost, and keeping converter transmission capacity constant during AC-side voltage boosting can reduce RMS value of arm currents while reducing converter cost, thereby reducing power loss of FBSMs and improving converter efficiency.

Abstract: Provided is an operating method of a full-bridge sub-module (FBSM)-based modular multilevel converter for HVDC transmission with AC-side voltage boosting. The peak value of the AC-side voltage is increased under a constant DC-link voltage by using FBSM's negative output voltage under steady state, wherein keeping the semiconductor's current rating constant during AC-side voltage boosting is in favor of reducing converter cost by decreasing energy interaction between the upper and lower arms in a leg, and further capacitance value of FBSM's capacitor under a constant capacitor voltage ripple, keeping the RMS value of AC-side current constant during AC-side voltage boosting can effectively improve transmission capacity of the converter while reducing converter cost, and keeping converter transmission capacity constant during AC-side voltage boosting can reduce RMS value of arm currents while reducing converter cost, thereby reducing power loss of FBSMs and improving converter efficiency.

Abstract: A ride-through and recovery method for DC short circuit faults of a hybrid modular multilevel converter based high-voltage direct current transmission (MMC-HVDC) system, the hybrid MMC including multiple full-bridge sub-modules and half-bridge sub-modules, and the method including: 1) detecting whether a DC short circuit fault occurs, and proceeding to step (2) if yes and continuing detecting if no; 2) realizing ride-through of the DC short circuit fault; 3) detecting whether a DC residual voltage increases, and proceeding to step (4) if yes and continuing detecting if no; and 4) realizing DC short circuit fault recovery.

Abstract: A power supply system, including an energy module, a controlled object, an active power controller, and an inertia-synchronization controller. The input end of the energy module operates to acquire external energy, a first output end of the energy module is connected to the controlled object, and the energy module operates to transform the acquired external energy into electric energy, or transform electric energy into electric energy having a different frequency therefrom. The input end of the active power controller is connected to a second output end of the energy module, the output end of the active power controller is connected to the controlled object, and the active power controller operates to control output active power of the controlled object. The input end of the inertia-synchronization controller operates to connect with an AC system. The output end of the inertia-synchronization controller is connected to the controlled object.

Abstract: A ride-through and recovery method for DC short circuit faults of a hybrid modular multilevel converter based high-voltage direct current transmission (MMC-HVDC) system, the hybrid MMC including multiple full-bridge sub-modules and half-bridge sub-modules, and the method including: 1) detecting whether a DC short circuit fault occurs, and proceeding to step (2) if yes and continuing detecting if no; 2) realizing ride-through of the DC short circuit fault; 3) detecting whether a DC residual voltage increases, and proceeding to step (4) if yes and continuing detecting if no; and 4) realizing DC short circuit fault recovery.