Rapid shutdown system and method for controlling the same

A rapid shutdown system, comprising:

• an inverter;
• and
• at least one photovoltaic string, wherein
• for each of the at least one photovoltaic string, input terminals of shutdown devices in the photovoltaic string are connected to respective photovoltaic modules, output terminals of the shutdown devices are connected in series to form two terminals of the photovoltaic string, and the two terminals of the photovoltaic string are connected to a direct current end of the inverter through a direct current bus;
• an alternating current end of the inverter is connected to a grid;
• and
• wherein:
• the inverter is configured to apply an electrical signal disturbance to the direct current bus connected to the shutdown devices at least once within each pre-shutdown period of the shutdown devices when the inverter operates in a mode of limited power output,
• a shutdown device of the shutdown devices is configured to sample an input parameter and/or an output parameter of the shutdown device determine, based on the sampled input parameter and/or the sampled output parameter, whether the electrical signal disturbance applied to the direct current bus meets a preset condition;
• the rapid shutdown system is configured to switch the shutdown device on or maintain the shutdown device in an ON state, in response to a determination result that the electrical signal disturbance already meets the preset condition;
• and
• the electrical signal disturbance is applied to the direct current bus through charging or discharging a bus capacitor in the inverter.