Huawei Technologies Co., Limited

Huawei Digital Power Technologies Co., Ltd.

Zhangping Shao

Kai Xin

You Zhou

Yunfeng Liu

Congyuan Wang

Haibin Guo

Rongliang Shi

A converter circuit is configured to output a first reactive current to a power grid when a voltage value of an output port of the converter circuit decreases from a first working voltage value to a second working voltage value. The drive control circuit is configured to: in a process in which the converter circuit outputs the first reactive current to the power grid, when it is detected that the voltage value of the output port of the converter circuit increases to a third working voltage value and the third working voltage value is greater than or equal to a first recovery voltage value, control the converter circuit to output a second reactive current to the power grid, to recover the voltage value of the output port of the converter circuit to the first working voltage value.

Power supply system and current conversion method

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.

Power conversion apparatus and control method for power conversion apparatus

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.

Inverter, power generating system, and method for suppressing harmonic distortion of alternating current system

An inverter anti-islanding control system includes a phase-shift loop () and a drive circuit (). The phase-shift loop () includes a first input end (), a second input end (), a third input end (), a fourth input end (), a first output end (), and a second output end (). The drive circuit () includes a first input end (), a second input end (), a third input end (), and an output end (). The first output end () of the phase-shift loop () is connected to the first input end () of the drive circuit (), and the second output end () of the phase-shift loop () is connected to the second input end () of the drive circuit (). In the inverter anti-islanding control system, when an inverter is in an island state, a frequency of an inverter alternating current end voltage is deviated to a second frequency by using the phase-shift loop (), so that the second frequency triggers frequency protection to disconnect the inverter from an electrical network, to be specific, the inverter is out of the island state.

Inverter anti-islanding control system

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.

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Shanghai, China

Zhangping Shao