Abstract: This application provides a power supply system and a conversion method. The power supply system includes a power generation apparatus, a converter circuit, and a drive control circuit. The drive control circuit may be configured to: when a power grid fails, control, based on duration of previous low voltage ride-through, the converter circuit to increase a value of a current to be output to the power grid from a first operating current value to a low voltage ride-through current value, to increase a voltage value at an output end of the converter circuit. Herein, the previous low voltage ride-through is latest low voltage ride-through. In this application, the system can control, based on duration of previous voltage ride-through, a current to be output by the converter circuit to the power grid, to reduce circuit oscillation, with a simple structure, a simple control method, and high safety.

Abstract: A power conversion apparatus and a control method for a power conversion apparatus to reduce an amplitude of an output voltage of a converter when a grid is recovered from a fault, to ensure device safety. The power conversion apparatus includes a controller and a converter, and the controller is connected to the converter. The controller is configured to: after the output voltage of the converter is less than a first threshold, when the output voltage of the converter rises to be greater than a second threshold, reduce an active current output by the converter to a first current value, and reduce a reactive current output by the converter to a second current value, where the second threshold is greater than the first threshold.

Abstract: A current control method and system for a voltage asymmetry fault is disclosed. When a voltage asymmetry fault occurs, a first current limit value is obtained based on a post-fault positive-sequence voltage and a pre-fault positive-sequence reactive current, and a second current limit value is obtained based on a post-fault negative-sequence voltage and a pre-fault negative-sequence voltage. A third current limit value and a fourth current limit value are obtained based on the first current limit value and the second current limit value. A magnitude of a positive-sequence reactive current is limited by using the third current limit value, and a magnitude of a negative-sequence reactive current is limited by using the fourth current limit value.

Abstract: Embodiments of this application provide a direct current bus voltage control method and apparatus, and a power system, and relate to the field of electric power technologies, to quickly identify a voltage between an inverter circuit and an alternating current grid, so as to timely control a voltage of a direct current bus, thereby improving stability of the power system. The method includes: obtaining an electrical parameter between the conversion circuit and the direct current bus; generating a predicted voltage between the inverter circuit and the alternating current grid based on the electrical parameter and a voltage prediction model; and controlling a voltage between the conversion circuit and the direct current bus based on the predicted voltage.

Abstract: An inverter includes an inverter circuit; an alternating current filter, where an input port of the alternating current filter is connected to an output port of the inverter circuit; an alternating current electromagnetic interference (EMI) filter; and a first alternating current switch, connected between an output port of the alternating current filter and an input port of the alternating current EMI filter. The first split capacitor is disposed between the first alternating current switch and the input port of the alternating current EMI filter; and when the first alternating current switch is turned off, the first split capacitor is disconnected from the output port of the alternating current filter, and the first split capacitor is connected to a circuit in which an alternating current system connected to the output port of the alternating current EMI filter is located, to suppress harmonic distortion of the alternating current system.

Abstract: An inverter includes an inverter circuit; an alternating current filter, where an input port of the alternating current filter is connected to an output port of the inverter circuit; an alternating current electromagnetic interference (EMI) filter; and a first alternating current switch, connected between an output port of the alternating current filter and an input port of the alternating current EMI filter. The first split capacitor is disposed between the first alternating current switch and the input port of the alternating current EMI filter; and when the first alternating current switch is turned off, the first split capacitor is disconnected from the output port of the alternating current filter, and the first split capacitor is connected to a circuit in which an alternating current system connected to the output port of the alternating current EMI filter is located, to suppress harmonic distortion of the alternating current system.

Abstract: An inverter anti-islanding control system includes a phase-shift loop (10) and a drive circuit (20). The phase-shift loop (10) includes a first input end (11), a second input end (12), a third input end (13), a fourth input end (14), a first output end (15), and a second output end (16). The drive circuit (20) includes a first input end (21), a second input end (22), a third input end (23), and an output end (24). The first output end (15) of the phase-shift loop (10) is connected to the first input end (21) of the drive circuit (20), and the second output end (16) of the phase-shift loop (10) is connected to the second input end (22) of the drive circuit (20).

Abstract: An islanding detection method and apparatus for an inverter, and a power supply system to resolve a problem that an existing voltage total harmonic distortion (THD)-based islanding detection method has low islanding detection reliability due to existence of a relatively large detection dead zone. According to this detection method, the voltage total harmonic distortion changes more significantly before and after the islanding effect of the inverter occurs in order to reduce an islanding detection dead zone and improve islanding detection reliability.

Abstract: An inverter anti-islanding control system includes a phase-shift loop (10) and a drive circuit (20). The phase-shift loop (10) includes a first input end (11), a second input end (12), a third input end (13), a fourth input end (14), a first output end (15), and a second output end (16). The drive circuit (20) includes a first input end (21), a second input end (22), a third input end (23), and an output end (24). The first output end (15) of the phase-shift loop (10) is connected to the first input end (21) of the drive circuit (20), and the second output end (16) of the phase-shift loop (10) is connected to the second input end (22) of the drive circuit (20).

Abstract: An islanding detection method and apparatus for an inverter, and a power supply system to resolve a problem that an existing voltage total harmonic distortion (THD)-based islanding detection method has low islanding detection reliability due to existence of a relatively large detection dead zone. According to this detection method, the voltage total harmonic distortion changes more significantly before and after the islanding effect of the inverter occurs in order to reduce an islanding detection dead zone and improve islanding detection reliability.