Rapid shutdown device for photovoltaic system and control method thereof and protection system

A control method for a rapid shutdown device, the rapid shutdown device being applied to a photovoltaic system, being connected between a photovoltaic power generation module and a photovoltaic inverter and comprising an input port and an output port, the rapid shutdown device further comprising:

• a first switch and a second switch, wherein a first terminal of the first switch is connected to one terminal of the input port, a second terminal of the first switch is connected to a first terminal of the second switch, and a second terminal of the second switch is connected to the other terminal of the input port;
• a third switch and a fourth switch, wherein the third switch is connected between the first terminal of the second switch and one terminal of the output port, and the fourth switch is connected between the second terminal of the second switch and the other terminal of the output port;
• and
• a controller, coupled to the control terminals of the first switch, the third switch, and the fourth switch respectively, and configured to control on and off of the first switch, the third switch, and the fourth switch, so that the rapid shutdown device operates in a normal state, a bypass state or a shutdown state;
• the control method comprising:
• when the rapid shutdown device operates in a shutdown state, detecting whether an online signal is received;
• in response to the rapid shutdown device operates in a shutdown state and the online signal is received, converting a state of the rapid shutdown device to a bypass state,
• when the rapid shutdown device operates in the bypass state, detecting whether the online signal is received, and acquiring an electrical parameter of the photovoltaic power generation module;
• and
• in response to the rapid shutdown device operates in the bypass state, the online signal is received, and the electrical parameter of the photovoltaic power generation module is higher than a set threshold, converting the state of the rapid shutdown device to a normal state.

A protection system for a photovoltaic system, comprising at least one rapid shutdown device, each of the at least one rapid shutdown device having an input port and an output port,

• wherein the photovoltaic system comprises at least one first photovoltaic power generation module and at least one second photovoltaic power generation module, and a photovoltaic inverter;
• each of the rapid shutdown devices comprising:
• a first switch and a second switch, wherein a first terminal of the first switch is connected to one terminal of the input port, a second terminal of the first switch is connected to a first terminal of the second switch, and a second terminal of the second switch is connected to the other terminal of the input port;
• a third switch and a fourth switch, wherein the third switch is connected between the first terminal of the second switch and one terminal of the output port, and the fourth switch is connected between the second terminal of the second switch and the other terminal of the output port;
• and
• a controller, coupled to the control terminals of the first switch, the third switch, and the fourth switch respectively, and configured to control on and off of the first switch, the third switch, and the fourth switch, so that the rapid shutdown device operates in a normal state, a bypass state or a shutdown state;
• wherein the input port of each of the at least one rapid shutdown device is coupled to a corresponding first photovoltaic power generation module, and the at least one second photovoltaic power generation module is connected in series with the output port of the rapid shutdown device.