A frequency detector detects a system frequency from an AC voltage on an AC power line to which a power conditioner performing system interconnection of a distributed power supply is connected. A power converter is configured to inject lead reactive power or delay reactive power into the AC power line. A controller controls reactive power output from the power converter to output the lead reactive power in response to an increase in the system frequency while outputting the delay reactive power in response to a decrease in the system frequency.

A power converter and a method. When the voltage at the grid connection point exceeds the preset voltage range and an amplitude of a voltage output by the power conversion circuit is not greater than a voltage threshold, embodiments can control the amplitude of the current output by the power conversion circuit to be not greater than a second current threshold, where the second current threshold is greater than the first current threshold, and a ratio of an active current to a reactive current output by the power conversion circuit is constant or changes; or, when the amplitude of the voltage output by the power conversion circuit is greater than the voltage threshold, embodiments can control the amplitude of the current output by the power conversion circuit to be equal to the second current threshold, where the ratio of the active current to the reactive current changes.

A power converter and a method. When the voltage at the grid connection point exceeds the preset voltage range and an amplitude of a voltage output by the power conversion circuit is not greater than a voltage threshold, embodiments can control the amplitude of the current output by the power conversion circuit to be not greater than a second current threshold, where the second current threshold is greater than the first current threshold, and a ratio of an active current to a reactive current output by the power conversion circuit is constant or changes; or, when the amplitude of the voltage output by the power conversion circuit is greater than the voltage threshold, embodiments can control the amplitude of the current output by the power conversion circuit to be equal to the second current threshold, where the ratio of the active current to the reactive current changes.

A dynamic frequency coordination control method for asynchronous regional power grids during wet and dry seasons is provided. By using frequency synchronous control in VSC-HVDC, frequency consistency and synchronization between the sending-end and receiving-end grids can be ensured within the range of power adjustment, enabling real-time and automatic sharing of frequency regulation resources between the two grids. Through the use of bilateral frequency limiting control in LCC-HVDC, the frequency regulation effect is enhanced, balancing frequency fluctuations between the sending-end and receiving-end grids. VSC-HVDC adaptive reactive power support control is employed to provide reactive power support to nearby LCC-HVDC, avoiding frequent operations of LCC-HVDC converter transformers and filters during frequency limiting control actions, thereby extending equipment lifespan. Furthermore, by utilizing grid-following and grid-forming control in renewable energy grid integration with additional frequency control, the frequency support capacity of renewable energy generation is improved.

A dynamic frequency coordination control method for asynchronous regional power grids during wet and dry seasons is provided. By using frequency synchronous control in VSC-HVDC, frequency consistency and synchronization between the sending-end and receiving-end grids can be ensured within the range of power adjustment, enabling real-time and automatic sharing of frequency regulation resources between the two grids. Through the use of bilateral frequency limiting control in LCC-HVDC, the frequency regulation effect is enhanced, balancing frequency fluctuations between the sending-end and receiving-end grids. VSC-HVDC adaptive reactive power support control is employed to provide reactive power support to nearby LCC-HVDC, avoiding frequent operations of LCC-HVDC converter transformers and filters during frequency limiting control actions, thereby extending equipment lifespan. Furthermore, by utilizing grid-following and grid-forming control in renewable energy grid integration with additional frequency control, the frequency support capacity of renewable energy generation is improved.

A dynamic frequency coordination control method for asynchronous regional power grids during wet and dry seasons is provided. By using frequency synchronous control in VSC-HVDC, frequency consistency and synchronization between the sending-end and receiving-end grids can be ensured within the range of power adjustment, enabling real-time and automatic sharing of frequency regulation resources between the two grids. Through the use of bilateral frequency limiting control in LCC-HVDC, the frequency regulation effect is enhanced, balancing frequency fluctuations between the sending-end and receiving-end grids. VSC-HVDC adaptive reactive power support control is employed to provide reactive power support to nearby LCC-HVDC, avoiding frequent operations of LCC-HVDC converter transformers and filters during frequency limiting control actions, thereby extending equipment lifespan. Furthermore, by utilizing grid-following and grid-forming control in renewable energy grid integration with additional frequency control, the frequency support capacity of renewable energy generation is improved.