Abstract: A power supply apparatus is coupled to an AC power source, a critical load, and a general load. The power supply apparatus includes a UPS, a generator system, a power conversion system, and a controller. The power conversion system includes a first power conversion path and a second power conversion path. The first power conversion path is connected to the critical load and an output side, and the second power conversion path is connected to the general load and an input side. The first power conversion path and the second power conversion path are jointly connected to a DC bus. When the controller determines that the AC power source is abnormal, the controller controls disconnecting the AC power source, and activates the UPS to supply power to the critical load so as to enable the first power conversion path and disable the second power conversion path.

Abstract: A power supply apparatus is coupled to an AC power source, a critical load, and a general load. The power supply apparatus includes a UPS, a generator system, a power conversion system, and a controller. The power conversion system includes a first power conversion path and a second power conversion path. The first power conversion path is connected to the critical load and an output side, and the second power conversion path is connected to the general load and an input side. The first power conversion path and the second power conversion path are jointly connected to a DC bus. When the controller determines that the AC power source is abnormal, the controller controls disconnecting the AC power source, and activates the UPS to supply power to the critical load so as to enable the first power conversion path and disable the second power conversion path.

Abstract: An electrical grid control device includes a data acquisition unit that acquires measurement data including a voltage value and a current value of each unit in an electrical grid in which a power conversion device is connected, and a control method selection unit that selects a control method when active power and reactive power output to the electrical grid by the power conversion device are controlled based on the acquired measurement data.

Abstract: An apparatus includes: an inverter converting generated power of renewable energy resources to predetermined alternating-current power for output to a power transmission network; a PWM control unit controlling the inverter; a first detecting unit detecting the input voltage and current to the inverter; a second detecting unit detecting the output voltage, current, and frequency of the inverter; a power change deciding unit calculating the input and output powers of the inverter and the difference therebetween from the voltage and current of each of the input and output detected by the detecting units, and calculating a correction output power command with reference to an output power command; and a virtual synchronous inertia control unit calculating a virtual inertia characteristic based on the voltage, current, and frequency of the output detected by the second detecting unit and the correction output power command, and outputting a reference command to a PWM control unit.

Abstract: An apparatus includes: an inverter converting generated power of renewable energy resources to predetermined alternating-current power for output to a power transmission network; a PWM control unit controlling the inverter; a first detecting unit detecting the input voltage and current to the inverter; a second detecting unit detecting the output voltage, current, and frequency of the inverter; a power change deciding unit calculating the input and output powers of the inverter and the difference therebetween from the voltage and current of each of the input and output detected by the detecting units, and calculating a correction output power command with reference to an output power command; and a virtual synchronous inertia control unit calculating a virtual inertia characteristic based on the voltage, current, and frequency of the output detected by the second detecting unit and the correction output power command, and outputting a reference command to a PWM control unit.

Abstract: A droop control system for grid-connected synchronization connects to a plurality of distributed power generation modules and a utility grid system. The droop control system includes a detection processing module and a plurality of regulation control modules corresponding to the distributed power generation modules. The detection processing module is coupled with the distributed power generation modules and utility grid system in parallel to obtain a voltage difference, a phase angle difference and a frequency difference. The regulation control modules perform droop control of real power-frequency variety and reactive power-voltage variety and phase angle compensation. Through reactive power-voltage variety droop control approach, impact of impedance alterations in the power system can be eliminated and voltage fluctuations can also be minimized to achieve stable effect. Hence electric power of the utility grid system and distributed power generation modules can be regulated synchronously.

Abstract: An LVRT control method for a grid-connected converter of distributed energy resources comprises steps of: obtain a positive sequence electrical component and a negative sequence electrical component during an LVRT period; outputting a compensation signal according to a power threshold withstood by a grid-connected converter to undertake reactive power compensation; and constraining the output power lower than the power threshold. The present invention uses the positive and negative sequence electrical components to undertake reactive power compensation, whereby to improve balance and stability of voltage during the LVRT period, avoid reverse torque and mechanical resonance, and prolong the service life of the power generator. Moreover, the present invention constrains the sum of the compensation currents below the power threshold to prevent the circuit of the power generator from being overloaded and damaged, whereby is prolonged the service life of the power system.