Electric power system and island protection method

Abstract

The invention discloses a power system and an island protection method, and belongs to the technical field of power electronics. The power system comprises a power converter and power switching equipment, the power switching equipment comprises a switch module and an electric signal sampling module, the switch module is configured to switch the on-off state between the power converter and a voltage source network, and the electric signal sampling module is configured to collect electric signals on the voltage source network side. According to the invention, grid-connected and off-grid switching of the power converter is realized through the power switching equipment, and whether the network side of the voltage source is electrified in the off-grid mode can be monitored through the preset target signal interacted between the power switching equipment and the power converter, so that the power converter is shut down under the condition that the preset target signal does not meet the preset condition, and the power conversion efficiency is improved. The safety problem that the voltage source network side is electrified in an off-grid state is solved, and the system safety is improved.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to a power system and an islanding protection method. Background Technology

[0002] In related technologies, the control of grid-connected and off-grid transfer switches largely relies on physical isolation and manual operation. However, in the off-grid situation, if the grid-connected or off-grid transfer switch experiences an internal short circuit fault or is accidentally closed, the voltage source network may become energized, thus posing a safety hazard. Summary of the Invention

[0003] This application provides a power system and islanding protection method, which aims to solve the safety problem of voltage source network side being energized in off-grid state.

[0004] In a first aspect, embodiments of this application provide a power system, which includes a power converter and a power switching device. The power switching device includes a switching module and an electrical signal sampling module. The switching module includes a first connection terminal and a second connection terminal. The first connection terminal is electrically connected to the power converter, and the second connection terminal is used to electrically connect to a voltage source network. The switching module is configured to switch the on / off state between the power converter and the voltage source network, and the electrical signal sampling module is configured to collect the electrical signal of the second connection terminal. The power switching equipment also includes a signal transmission end, which is electrically connected to the power converter. The power switching equipment is configured to transmit a preset target signal to the power converter through the signal transmission end. The power converter is configured to operate in off-grid mode, and stops outputting power when the preset target signal does not meet the preset conditions.

[0005] In some embodiments, the preset target signal includes at least one of the electrical signal of the second connection terminal and the on / off state signal of the switching module; The power converter is configured to determine that a preset target signal does not meet preset conditions, including: It is determined that the electrical signal at the second connection terminal does not meet the preset electrical signal threshold range, and / or it is determined that the on / off state signal of the switch module does not meet the preset state signal.

[0006] In some embodiments, the electrical signal sampling module includes a voltage acquisition unit, which is used to acquire the voltage signal of the second connection terminal; The power converter is configured to determine that the electrical signal at the second connection terminal does not meet a preset electrical signal threshold range, including: Determine that the voltage signal at the second connection terminal is greater than the preset voltage signal.

[0007] In some embodiments, the electrical signal sampling module includes a current acquisition unit, which is used to acquire the current signal of the second connection terminal; The power converter is configured to determine that the electrical signal at the second connection terminal does not meet a preset electrical signal threshold range, including: Determine that the current signal at the second connection terminal is greater than the preset current signal.

[0008] In some embodiments, the electrical signal sampling module includes a frequency acquisition unit, which is used to acquire the voltage frequency signal of the second connection terminal; The power converter is configured to determine that the electrical signal at the second connection terminal does not meet a preset electrical signal threshold range, including: Determine that the voltage frequency signal at the second connection terminal is greater than the preset voltage frequency signal.

[0009] In some embodiments, the on / off state signal of the switching module includes an off state signal and an on state signal; The power converter is configured to determine if the on / off state signal of the switching module does not meet a preset state signal, including: The on / off status signal of the switch module is determined to be an off signal.

[0010] In some embodiments, the signal transmission end includes a communication end and a physical contact output end. The communication end is configured to transmit electrical signals of the second connection end to the power converter, and the physical contact output end is configured to transmit on / off status signals of the switching module to the power converter.

[0011] In some embodiments, the power switching device further includes a micro switch connected between the switching module and the physical contact output terminal. The on / off state signal of the micro switch is configured to characterize the on / off state signal of the switching module. When the on / off state signal of the micro switch is a contact closed state signal, the switching module is in an open state signal; when the on / off state signal of the micro switch is a contact open state signal, the switching module is in a conducting state. The power converter is configured to determine that the on / off state signal of the switching module is an off signal, including: The on / off state signal of the micro switch is determined to be the contact open state signal.

[0012] In some embodiments, when the power switching device is powered by a voltage source network, the preset target signal includes the on / off status signal of the switching module.

[0013] In some embodiments, the power converter is also configured to operate in off-grid mode, and to stop outputting power if communication between the power switching device and the power converter is interrupted for more than a preset duration.

[0014] In some embodiments, the power converter is further configured to operate in off-grid mode and output power normally when the preset target signal meets preset conditions.

[0015] Secondly, embodiments of this application also provide an islanding protection method, applied to the power system as described in the above embodiments, the islanding protection method comprising: When the power converter is operating in off-grid mode and the preset target signal does not meet the preset conditions, the power converter stops outputting power.

[0016] Beneficial Effects: This application provides a power system including a power converter and a power switching device. The power switching device includes a switching module and an electrical signal sampling module. The switching module is configured to switch the on / off state between the power converter and the voltage source network, and the electrical signal sampling module is configured to collect electrical signals from the voltage source network side. This application realizes the grid-connected / off-grid switching of the power converter through the power switching device. Furthermore, through the preset target signal exchanged between the power switching device and the power converter, it can monitor whether the voltage source network side is energized in off-grid mode. Therefore, if the preset target signal does not meet the preset conditions, the power converter shuts down, solving the safety problem of the voltage source network side being energized in off-grid mode and improving system safety.

[0017] This application also provides an islanding protection method, which is applied to the power system described above. Therefore, the islanding protection method can have all the technical features and effects of the power system, which will not be elaborated here. Attached Figure Description

[0018] Figure 1 A schematic diagram of the structure of a power system provided in this application embodiment; Figure 2 This is a schematic diagram of the structure of a power switching device provided in an embodiment of this application; Figure 3 This is a schematic diagram of another power switching device provided in an embodiment of this application.

[0019] Explanation of reference numerals in the attached figures: 100. Power converter; 200. Power switching device; 210. Switching module; 211. First connection terminal; 212. Second connection terminal; 220. Electrical signal sampling module; 221. Voltage acquisition unit; 222. Current acquisition unit; 223. Frequency acquisition unit; 230. Signal transmission terminal; 231. Communication terminal; 232. Physical contact output terminal; 240. Micro switch; 300. Voltage source network. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] The use of "applies to" or "configured to" in this application implies open and inclusive language, which does not exclude the applicability to or configuration to devices performing additional tasks or steps. Additionally, the use of "based on" implies openness and inclusivity, because processes, steps, calculations, or other actions "based on" one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0023] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0024] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.

[0025] In new energy systems, the power converter 100, as a key device capable of supplying power to the load in both grid-connected and off-grid modes, is typically equipped with a grid-connected / off-grid switching switch or a grid-connected / off-grid switching box to achieve switching between grid-connected and off-grid operation modes. The generated DC power supply can sequentially pass through the power converter 100 and the distribution box before being connected to the voltage source network 300, and the energy storage DC power supply can also sequentially pass through the power converter 100 and the distribution box before being connected to the voltage source network 300. The distribution box may be equipped with a grid-connected / off-grid switching switch. When the voltage source network 300 is energized, the grid-connected / off-grid switching switch is in the closed state, and the power converter 100 and the voltage source network 300 jointly supply power to the load. When the voltage source network 300 is de-energized, the grid-connected / off-grid switching switch is in the open state, and the power converter 100 operates off-grid, supplying power to the load independently.

[0026] Among them, grid-connected / off-grid transfer switches mostly adopt mechanical or solid-state relay solutions, which physically disconnect or close the voltage source network 300 to achieve isolation between the system and the voltage source network 300. However, in off-grid operation, if the grid-connected / off-grid transfer switch experiences an internal short circuit fault or is accidentally closed, the voltage source network 300 side will be accidentally energized, resulting in serious safety hazards. In particular, during system installation, maintenance, or repair, personnel on the voltage source network 300 side may mistakenly believe that the voltage source network 300 is in a de-energized state and perform operations, thereby causing electric shock accidents, violating the basic safety requirements of the grid connection standard for the voltage source network 300.

[0027] In related technologies, the control of grid-connected and off-grid transfer switches largely relies on physical isolation and manual operation, lacking a real-time sensing and feedback mechanism for the switch status. After an abnormal switch closure, the power converter 100 cannot promptly determine whether the voltage source network 300 is energized, thus failing to take effective protective measures. Although some systems prevent misoperation by setting physical locking mechanisms or mechanical interlocks, in practical applications, such designs are highly dependent on human operation and struggle to cope with unexpected situations such as internal switch faults or communication interruptions. Furthermore, they do not adequately consider situations where communication is abnormal, such as communication interruption between the grid-connected and off-grid transfer switch and the power converter 100, lack of heartbeat signal, or data loss, which may still cause system misjudgment or protection mechanism failure, further increasing operational risks.

[0028] In view of the above, embodiments of this application provide a power system aimed at solving at least one of the above-mentioned technical problems.

[0029] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a power system provided in an embodiment of this application.

[0030] This application provides a power system comprising a power converter 100 and a power switching device 200. The power switching device 200 includes a switching module 210 and an electrical signal sampling module 220. The switching module 210 includes a first connection terminal 211 and a second connection terminal 212. The first connection terminal 211 is electrically connected to the power converter 100, and the second connection terminal 212 is electrically connected to a voltage source network 300. The switching module 210 is configured to switch the on / off state between the power converter 100 and the voltage source network 300. The electrical signal sampling module 220 is configured to collect the electrical signal from the second connection terminal 212. The power switching device 200 also includes a signal transmission terminal 230, which is electrically connected to the power converter 100. The power switching device 200 is configured to transmit a preset target signal to the power converter 100 through the signal transmission terminal 230. The power converter 100 is configured to operate in off-grid mode, and if the preset target signal does not meet preset conditions, it stops outputting electrical energy.

[0031] The voltage source network 300 refers to a power network or independent power supply device that can receive externally input AC power and realize the transmission, distribution and dispatch of power. For example, the voltage source network 300 can be, but is not limited to, a public power grid or a generator (such as a diesel generator or a gas generator).

[0032] The power converter 100 is connected between the DC power supply and the power switching device 200. The power converter 100 is used to convert the DC voltage of the DC power supply into AC voltage, thereby supplying power to AC loads or connecting AC power to the voltage source network 300 via the power switching device 200; or, the power converter 100 can also convert the AC voltage of the voltage source network 300 into DC voltage and input it into the DC power supply.

[0033] Please continue reading. Figure 1 Specifically, a DC power supply can include a generator and / or an energy storage power supply. In other words, a DC power supply can include a generator and an energy storage power supply, or a generator and an energy storage power supply.

[0034] For example, a power source for generating electricity can be a device that converts other forms of energy into direct current (DC) electrical energy. For instance, in solar power generation, the power source can include photovoltaic (PV) panels. Similarly, in wind power, thermal power, and hydropower generation, the power source can include a DC generator that outputs DC voltage. An energy storage power source can be a device that performs DC voltage charging and discharging. For example, an energy storage power source can include energy storage batteries, which can be, but are not limited to, lead-acid batteries, lithium-ion batteries, sodium-sulfur batteries, nickel-metal hydride batteries, and nickel-cadmium batteries.

[0035] The power converter 100 may include a DC-DC conversion circuit and an AC-DC conversion circuit. For example, the DC-DC conversion circuit may include, but is not limited to, a BOOST boost circuit, a BUCK buck circuit, or a BOOST-BUCK buck-boost circuit. The AC-DC conversion circuit may include, but is not limited to, a half-bridge inverter circuit, a full-bridge inverter circuit, or a push-pull inverter circuit.

[0036] Please continue reading. Figure 1 The power switching device 200 is installed in the distribution box to switch the on / off state between the power converter 100 and the voltage source network 300. Normally, the power converter 100 operates in grid-connected mode, and the path between the power converter 100 and the voltage source network 300 is conductive. When the power converter 100 operates in off-grid mode, the path between the power converter 100 and the voltage source network 300 is disconnected. Additionally, Figure 1 In this circuit, switch K1 controls the electrical connection between the power converter 100 and the power switching device 200; switch K2 controls the electrical connection between the power converter 100 and the load; and switch K3 controls the electrical connection between the power switching device 200 and the power grid. For example, switches K1, K2, and K3 can be circuit breakers, which can be manually controlled to close and open. Normally, switches K1, K2, and K3 are all closed. The power switching device 200 sets the on / off state between the power converter 100 and the voltage source network 300. Switches K1, K2, and K3 can control the on / off state of the corresponding lines as needed.

[0037] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of a power switching device provided in an embodiment of this application.

[0038] The power switching device 200 includes a switching module 210 and an electrical signal sampling module 220. The first connection terminal 211 of the switching module 210 is electrically connected to the power converter 100, and the second connection terminal 212 of the switching module 210 is electrically connected to the voltage source network 300. The switching module 210 is configured to switch the on / off state between the power converter 100 and the voltage source network 300. Specifically, the power switching device 200 can control the switching module 210 to switch the electrical on / off state between the power converter 100 and the voltage source network 300 by opening and closing its internal contact mechanism in response to commands from the power converter 100.

[0039] The electrical signal sampling module 220 is configured to collect the electrical signal from the second connection terminal 212. That is, the electrical signal sampling module 220 is electrically connected to the voltage source network 300 connected to the second connection terminal 212 of the switch module 210. Therefore, the electrical signal sampling module 220 can collect the electrical signal from the power grid side of the switch module 210, and thus determine whether the voltage source network 300 is energized. Specifically, the electrical signal sampling module 220 may include, but is not limited to, at least one of a voltage sampling structure, a current sampling structure, and a voltage-frequency sampling structure, thereby collecting at least one of voltage, current, and frequency.

[0040] The power switching device 200 also includes a signal transmission terminal 230, which is electrically connected to the power converter 100. The power switching device 200 is configured to transmit a preset target signal to the power converter 100 through the signal transmission terminal 230. The preset target signal may include, but is not limited to, at least one of the following: the electrical signal from the second connection terminal 212 collected by the electrical signal sampling module 220, the on / off state of the switch module 210, etc., thereby enabling the power converter 100 to sense changes in the switch state and the energized state of the power grid. It should be noted that the power switching device 200 can also receive corresponding commands from the power converter 100 through the signal transmission terminal 230 to control the switch module 210 to open and close through its internal contact mechanism. The signal transmission terminal 230 can be configured to realize bidirectional data interaction between the power switching device 200 and the power converter 100, capable of transmitting signals such as power grid status and switch opening / closing to the power converter 100, and also capable of receiving signals such as control and feedback operating status and fault information from the power converter 100.

[0041] The power converter 100 is configured to operate in off-grid mode and stop outputting power if the preset target signal does not meet preset conditions. Specifically, the power converter 100 is configured to continuously receive the preset target signal from the signal transmission terminal 230 when operating in off-grid mode. If the preset target signal does not meet the preset conditions, the power converter 100 will automatically stop outputting power, enabling the power converter 100 to standby or shut down, thus achieving active power outage protection on the grid side and ensuring system safety.

[0042] Through the above technical solution, this application provides a power system including a power converter 100 and a power switching device 200. The power switching device 200 includes a switching module 210 and an electrical signal sampling module 220. The switching module 210 is configured to switch the on / off state between the power converter 100 and the voltage source network 300, and the electrical signal sampling module 220 is configured to collect electrical signals from the voltage source network 300 side. This application realizes the grid-connected / off-grid switching of the power converter 100 through the power switching device 200. Furthermore, through the preset target signal exchanged between the power switching device 200 and the power converter 100, it can monitor whether the voltage source network 300 side is energized in off-grid mode. Therefore, if the preset target signal does not meet the preset conditions, the power converter 100 shuts down, solving the safety problem of the voltage source network 300 side being energized in off-grid mode and improving system safety.

[0043] In some embodiments, the preset target signal includes at least one of the electrical signal of the second connection terminal 212 and the on / off state signal of the switch module 210; the power converter 100 is configured to determine that the preset target signal does not meet the preset conditions, including: the electrical signal of the second connection terminal 212 does not meet the preset electrical signal threshold range, and the on / off state signal of the switch module 210 does not meet at least one of the preset state signals.

[0044] In other words, in some examples, the preset target signal includes the electrical signal at the second connection terminal 212; the power converter 100 is configured to determine that the preset target signal does not meet preset conditions, including: the electrical signal at the second connection terminal 212 does not meet the preset electrical signal threshold range. Specifically, when the power converter 100 is operating in off-grid mode, it means that the switching module 210 should disconnect the path between the power converter 100 and the voltage source network 300, and thus the voltage source network 300 should have no electrical signal. Therefore, if the electrical signal at the second connection terminal 212 does not meet the preset electrical signal threshold range, it means that the voltage source network 300 is abnormally energized, and the power converter 100 can control itself to stop outputting power, thereby achieving active power-off protection on the grid side and improving system operation safety.

[0045] In other examples, the preset target signal includes the on / off state signal of the switch module 210; the power converter 100 is configured to determine that the preset target signal does not meet preset conditions, including: the on / off state signal of the switch module 210 does not meet at least one of the preset state signals. Specifically, when the power converter 100 is operating in off-grid mode, it means that the switch module 210 should disconnect the path between the power converter 100 and the voltage source network 300, and thus the voltage source network 300 should have no electrical signal. Therefore, if the on / off state of the switch module 210 is closed, it may cause the voltage source network 300 to be abnormally energized. In this case, the power converter 100 can control itself to stop outputting power, thereby realizing active power-off protection and improving the safety of system operation.

[0046] In some other examples, the preset target signal includes the electrical signal of the second connection terminal 212 and the on / off state signal of the switch module 210. The power converter 100 is configured to determine that the preset target signal does not meet preset conditions, including: the electrical signal of the second connection terminal 212 does not meet a preset electrical signal threshold range, or the on / off state signal of the switch module 210 does not meet at least one of the preset state signals. Specifically, when the power converter 100 is operating in off-grid mode, if either the on / off state of the switch module 210 is closed or the electrical signal of the second connection terminal 212 does not meet a preset electrical signal threshold range, it indicates that the voltage source network 300 is abnormally energized. The power converter 100 can then control itself to stop outputting power, thereby achieving active power-off protection and improving system operational safety.

[0047] It should be noted that when the power converter 100 is operating in off-grid mode, if the electrical signal of the second connection terminal 212 meets the preset electrical signal threshold range and the on / off state signal of the switch module 210 meets the preset state signal, it means that the preset target signal meets the preset conditions, and thus the power converter 100 can output electrical energy normally.

[0048] Understandably, this application uses at least one of the electrical signal of the second connection terminal 212 and the on / off state signal of the switch module 210 as a preset target signal for judgment. This allows the system operating condition to be verified from two dimensions: electrical parameters and equipment status. When either dimension fails to meet the preset conditions, the power converter 100 can be triggered to control itself to stop outputting electrical energy. This improves the accuracy and comprehensiveness of the operating condition judgment and can quickly identify two typical faults: electrical abnormality and switch status abnormality, thus ensuring the safety and reliability of the power converter 100 operation.

[0049] Please see Figure 3 , Figure 3 This is a schematic diagram of another power switching device provided in an embodiment of this application.

[0050] In some embodiments, the electrical signal sampling module 220 includes a voltage acquisition unit 221, which is used to acquire the voltage signal of the second connection terminal 212; the power converter 100 is configured to determine that the electrical signal of the second connection terminal 212 does not meet the preset electrical signal threshold range, including: the voltage signal of the second connection terminal 212 is greater than the preset voltage signal.

[0051] Specifically, the voltage acquisition unit 221 is electrically connected to the second connection terminal 212 of the switch module 210 and is used to acquire the voltage signal of the second connection terminal 212. That is, the voltage acquisition unit 221 is used to acquire the voltage signal of the voltage source network 300 connected to the second connection terminal 212. The power converter 100 is configured to determine whether the electrical signal of the second connection terminal 212 meets a preset electrical signal threshold range, specifically including: determining whether the voltage signal of the second connection terminal 212 is greater than a preset voltage signal. If the voltage signal of the second connection terminal 212 is greater than the preset voltage signal, the power converter 100 determines that the electrical signal of the second connection terminal 212 does not meet the preset electrical signal threshold range, and the power converter 100 controls itself to stop outputting power to avoid overvoltage operation or islanding effect, thereby improving system operating safety. If the voltage signal of the second connection terminal 212 is less than or equal to the preset voltage signal, the power converter 100 determines that the electrical signal of the second connection terminal 212 meets the preset electrical signal threshold range, and the power converter 100 can output power normally.

[0052] For example, the voltage signal at the second connection terminal 212 and the preset voltage signal can be compared using their corresponding voltage values. The voltage acquisition unit 221 can output the acquired voltage signal to the control module of the power switching device 200, which then outputs it to the power converter 100 via the signal transmission terminal 230. The power converter 100 performs calculations to convert the voltage signal into a corresponding voltage value, thereby comparing the voltage signal at the second connection terminal 212 and the preset voltage signal using their corresponding voltage values. If the preset voltage signal corresponds to a voltage value of 36V, then if the voltage value corresponding to the voltage signal at the second connection terminal 212 is greater than 36V, the power converter 100 will stop outputting power. If the voltage value corresponding to the voltage signal at the second connection terminal 212 is less than or equal to 36V, the power converter 100 can output power normally. It should be noted that the power converter 100 and the voltage source network 300 can be connected by a single-phase cable or a multi-phase cable. As long as the voltage value corresponding to the voltage signal of any one phase second connection terminal 212 is greater than 36V, the power converter will control itself to stop outputting electrical energy.

[0053] It should also be noted that the voltage acquisition unit 221 may include a resistor voltage divider circuit, or other voltage acquisition circuits may be used, which will not be elaborated here. Additionally, a corresponding voltage sampling module may be provided to acquire the voltage at the first connection terminal 211 of the switch module 210, that is, to acquire the voltage of the power converter 100 connected to the first connection terminal 211. All phase voltages are based on the neutral line (N line).

[0054] Please continue reading. Figure 3 In some embodiments, the electrical signal sampling module 220 includes a current acquisition unit 222, which is used to acquire the current signal of the second connection terminal 212; the power converter 100 is configured to determine that the electrical signal of the second connection terminal 212 does not meet the preset electrical signal threshold range, including: the current signal of the second connection terminal 212 is greater than the preset current signal.

[0055] Specifically, the current acquisition unit 222 is electrically connected to the second connection terminal 212 of the switch module 210 and is used to acquire the current signal of the second connection terminal 212. In other words, the current acquisition unit 222 is used to acquire the current signal of the current source network connected to the second connection terminal 212. The power converter 100 is configured to determine whether the electrical signal of the second connection terminal 212 meets a preset electrical signal threshold range, specifically including: determining whether the current signal of the second connection terminal 212 is greater than a preset current signal. If the current signal of the second connection terminal 212 is greater than the preset current signal, the power converter 100 determines that the electrical signal of the second connection terminal 212 does not meet the preset electrical signal threshold range, and the power converter 100 controls itself to stop outputting power to avoid overcurrent operation, islanding effect, or abnormal power supply, thereby improving system operating safety. If the current signal of the second connection terminal 212 is less than or equal to the preset current signal, the power converter 100 determines that the electrical signal of the second connection terminal 212 meets the preset electrical signal threshold range, and the power converter 100 can output power normally.

[0056] For example, the current signal at the second connection terminal 212 and the preset current signal can be compared using their corresponding current values. The current acquisition unit 222 can output the acquired current signal to the control module of the power switching device 200, which then outputs it to the power converter 100 via the signal transmission terminal 230. The power converter 100 performs calculations to convert the current signal into a corresponding current value, thereby comparing the current signal at the second connection terminal 212 and the preset current signal using their corresponding current values. The current value corresponding to the preset current signal can be 0.5A. If the current value corresponding to the current signal at the second connection terminal 212 is greater than 0.5A, the power converter 100 will stop outputting power. If the current value corresponding to the current signal at the second connection terminal 212 is less than or equal to 0.5A, the power converter 100 can output power normally. It should be noted that the power converter 100 and the current source network can be connected by a single-phase cable or a multi-phase cable. As long as the current value corresponding to the current signal of any one phase second connection terminal 212 is greater than 0.5A, the power converter will control itself to stop outputting electrical energy.

[0057] It should also be noted that the current acquisition unit 222 can sample the current signal through a current transformer, or the current acquisition unit 222 can also use other current acquisition circuits, which will not be elaborated here.

[0058] Please continue reading. Figure 3 In some embodiments, the electrical signal sampling module 220 includes a frequency acquisition unit 223, which is used to acquire the voltage frequency signal of the second connection terminal 212; the power converter 100 is configured to determine that the electrical signal of the second connection terminal 212 does not meet the preset electrical signal threshold range, including: the voltage frequency signal of the second connection terminal 212 is greater than the preset voltage frequency signal.

[0059] Specifically, the frequency acquisition unit 223 is electrically connected to the second connection terminal 212 of the switch module 210 and is used to acquire the frequency signal of the second connection terminal 212. That is, the frequency acquisition unit 223 is used to acquire the voltage frequency signal of the frequency source network connected to the second connection terminal 212. The power converter 100 is configured to determine whether the electrical signal of the second connection terminal 212 meets a preset electrical signal threshold range, specifically including: determining whether the voltage frequency signal of the second connection terminal 212 is greater than a preset voltage frequency signal. If the voltage frequency signal of the second connection terminal 212 is greater than the preset voltage frequency signal, the power converter 100 determines that the electrical signal of the second connection terminal 212 does not meet the preset electrical signal threshold range, and the power converter 100 controls itself to stop outputting power to avoid frequency abnormalities, islanding operation, or unexpected grid connection, thereby improving the safety and stability of system operation. If the voltage frequency signal of the second connection terminal 212 is less than or equal to a preset frequency value, the power converter 100 determines that the electrical signal of the second connection terminal 212 meets the preset electrical signal threshold range, and the power converter 100 can output power normally.

[0060] For example, the voltage frequency signal of the second connection terminal 212 and the preset voltage frequency signal can be compared using their corresponding voltage frequency values. The frequency acquisition unit 223 can be integrated into the control module of the power switching device 200. The control module of the power switching device 200 obtains the corresponding voltage frequency signal based on the voltage signal acquired by the voltage acquisition unit 221 by detecting the voltage zero-crossing point. Then, the control module outputs the signal to the power converter 100 through the signal transmission terminal 230. The power converter 100 performs calculations to convert the voltage frequency signal into a corresponding voltage frequency value, thereby comparing the voltage frequency signal of the second connection terminal 212 with the preset voltage frequency signal using their corresponding voltage frequency values. The frequency value corresponding to the preset voltage frequency signal can be 45Hz. If the frequency value is greater than 45Hz, the power converter 100 controls itself to stop outputting power. If the frequency value of the second connection terminal 212 is less than or equal to 45Hz, the power converter 100 can output power normally. It should be noted that the power converter 100 and the frequency source network can be connected by a single-phase cable or a multi-phase cable. As long as the frequency value of any one of the second connection terminals 212 is greater than 45Hz, the power converter 100 will control itself to stop outputting electrical energy.

[0061] It should be noted that the voltage, current, and voltage frequency values ​​described above can be effective voltage values, effective current values, and effective voltage frequency values. The control module of the power switching device 200 can be, but is not limited to, a microcontroller unit (MCU), or other programmable logic devices or embedded processing units known to those skilled in the art, such as, but not limited to, digital signal processors (DSPs) and field-programmable gate arrays (FPGAs).

[0062] In some embodiments, the electrical signal sampling module 220 may include at least one of a voltage acquisition unit 221, a current acquisition unit 222, and a frequency acquisition unit 223. The power converter 100 is configured to determine that the electrical signal at the second connection terminal 212 does not meet a preset electrical signal threshold range, including: The system determines at least one of the following: the voltage signal of the second connection terminal 212 is greater than a preset voltage signal; the current signal of the second connection terminal 212 is greater than a preset current signal; or the voltage frequency signal of the second connection terminal 212 is greater than a preset voltage frequency signal.

[0063] It is important to understand that the process of determining that the voltage signal of the second connection terminal 212 is greater than the preset voltage signal, confirming that the current signal of the second connection terminal 212 is greater than the preset current signal, and determining that the voltage frequency signal of the second connection terminal 212 is greater than the preset voltage frequency signal can be referred to the previous description, and will not be repeated here.

[0064] It should also be noted that in some examples, the power switching device 200 can be configured to determine that the electrical signal of the second connection terminal 212 does not meet the preset electrical signal threshold range. That is, the judgment and calculation process performed by the power converter 100 described above can also be performed in the control module within the power switching device 200. The control module of the power switching device 200 can output the judgment result to the power converter 100 through the signal transmission terminal 230. Then, the power converter 100 can decide whether to output electrical energy normally based on the judgment result received from the power switching device 200.

[0065] It is understood that the power system provided in this application embodiment establishes a bidirectional communication link based on the electrical connection between the signal transmission terminal 230 and the power converter 100, enabling the power converter 100 to obtain the current status of the power switching device 200 and the electrical parameters of the grid side it detects in real time, so as to take timely and effective power outage safety measures when abnormal closing or line short circuit causes abnormal energization on the grid side.

[0066] When the power converter 100 is configured to operate in off-grid mode, it means that the switching module 210 in the power switching device 200 should be in the open state. The power converter 100 can exchange signals with the power switching device 200 through the signal transmission terminal 230, and the power converter 100 maintains its operation in off-grid mode. If the switching module 210 in the power switching device 200 experiences an internal short circuit fault or is mistakenly closed, its integrated voltage, current, frequency, and other acquisition units will collect the electrical parameters of the grid side in real time and feed these parameters back to the power converter 100 through the communication link corresponding to the signal transmission terminal 230. After receiving these data, the power converter 100 determines whether the grid is energized based on the preset electrical signal threshold range. For example, when the effective value of the grid voltage is greater than the effective value of the voltage corresponding to the preset voltage signal, or the effective value of the grid current is greater than the effective value of the current corresponding to the preset current signal, or the effective value of the frequency is greater than the effective value of the frequency corresponding to the preset voltage frequency signal, the power converter 100 determines that the grid has been accidentally energized and immediately performs an internal relay disconnection operation to cut off the output power to the grid, and at the same time switches the system state to fault, standby or shutdown mode.

[0067] It should be noted that, in order to ensure response speed and judgment accuracy, the voltage and current acquisition unit 222 in this embodiment should have a high sampling frequency (e.g., not less than 1kHz) and use digital signal processing algorithms for filtering and feature extraction.

[0068] Please continue reading. Figure 3 In some embodiments, the on / off state signal of the switch module 210 includes an off state signal and an on state signal; the power converter 100 is configured to determine that the on / off state signal of the switch module 210 does not satisfy a preset state signal, including: determining that the on / off state signal of the switch module 210 is an off signal.

[0069] Specifically, when the power converter 100 is configured to operate in off-grid mode, it can acquire the on / off status signal of the switching module 210 through the signal transmission terminal 230 and determine whether the on / off status signal of the switching module 210 meets a preset status signal. That is, if it determines that the switching module 210 is in the on state, and further determines that the on / off status signal of the switching module 210 does not meet the preset status signal, it will control itself to stop outputting power to avoid abnormal grid connection or islanding operation and improve system operation safety. Conversely, if it determines that the switching module 210 is in the off state, and further determines that the on / off status signal of the switching module 210 meets the preset status signal, it will control itself to output power normally.

[0070] For example, please continue reading Figure 3The control module in the power switching device 200 can switch the mechanical on / off state of the switch module 210 by driving a gear system with a motor. The control module is also configured to acquire the mechanical position information of the gear system through position feedback, and determine the current on / off state of the switch module 210 based on this information. After determining the on / off state of the switch module 210, the control module in the power switching device 200 can transmit a status signal representing the on / off state of the switch module 210 to the power converter 100 via an information transmission terminal. This on / off status signal is an electrical signal, which the power converter 100 can identify and process.

[0071] Please continue reading. Figure 3 In some embodiments, the signal transmission terminal 230 includes a communication terminal 231 and a physical contact output terminal 232. The communication terminal 231 is configured to transmit electrical signals of the second connection terminal 212 to the power converter 100, and the physical contact output terminal 232 is configured to transmit on / off status signals of the switch module 210 to the power converter 100.

[0072] Specifically, communication terminal 231 is configured to establish a bidirectional data communication link with power converter 100 to achieve real-time information interaction between the two. The communication mechanism of the bidirectional data communication link can be built based on commonly used industrial protocols such as RS485, CAN, Ethernet, or wireless communication (such as Wi-Fi, Bluetooth, ZigBee). The establishment and maintenance process of the communication link may include initialization configuration, heartbeat signal transmission, status and parameter request response, etc. The specific implementation method can refer to the existing technology in this field, and will not be elaborated here. When power converter 100 is operating normally, power converter 100 can periodically send heartbeat signals and status query commands to power switching device 200 to confirm that it is in a normal communication state and obtain the current electrical signals on the grid side, and can also obtain the on / off status information of switch module 210. Meanwhile, when the power switching device 200 detects a change in its own status (such as the opening and closing action of the switch module 210, fault triggering, grid abnormality, etc.), it can also actively send status update information to the power converter 100. This communication link serves as an information interaction channel between the power converter 100 and the power switching device 200.

[0073] The physical contact output terminal 232 is a hardware signal output port independent of the communication terminal 231. It is configured to output a switching signal to the power converter 100 in the form of a passive contact to characterize the on / off state of the switch module 210. The physical contact output terminal 232 is linked to the mechanical position of the switch module 210, so that the output state of the physical contact output terminal 232 is determined by the actual mechanical position of the switch module 210. The physical contact output terminal 232 only provides two hardware physical states: contact on or contact off. It does not provide voltage or drive current externally, and directly characterizes the actual mechanical position of the switch module 210 through the contact on / off state.

[0074] Understandably, this embodiment of the application sets the signal transmission terminal 230 as a dual signal transmission structure combining the communication terminal 231 and the physical contact output terminal 232. This allows for real-time interaction between the electrical signal of the second connection terminal 212 and the switch status electrical signal via the communication terminal 231, meeting the power converter 100's requirements for refined control of grid parameters. Furthermore, the physical contact output terminal 232 enables reliable hardware-level output of the on / off status of the switch module 210, preventing loss or misjudgment of status information due to communication anomalies. This improves the stability and reliability of information interaction between the power switching device 200 and the power converter 100, ensuring system safety. Moreover, through this hardware-level signal output method, the physical contact output terminal 232 possesses strong anti-interference capabilities and is unaffected by communication interruptions, power supply anomalies, or data packet loss, providing the power converter 100 with highly reliable switch status interlocking information.

[0075] In some embodiments, the power switching device 200 further includes a micro switch 240 connected between the switch module 210 and the physical contact output terminal 232. The on / off state signal of the micro switch 240 is configured to characterize the on / off state signal of the switch module 210. When the on / off state signal of the micro switch 240 is a contact closed state signal, the switch module 210 is in an open state signal; when the on / off state signal of the micro switch 240 is a contact open state signal, the switch module 210 is in a conducting state. The power converter 100 is configured to determine that the on / off state signal of the switch module 210 is an open signal, including: determining that the on / off state signal of the micro switch 240 is a contact open state signal.

[0076] It should be understood that the micro switch 240 is a mechanical switching element. The micro switch 240 is mechanically linked to the contact mechanism within the switch module 210. In this embodiment, the micro switch 240 and the switch module 210 can employ a physically anti-phase linkage structure. Therefore, when the contact mechanism within the switch module 210 is in the open state, the mechanical linkage mechanism causes the contacts of the micro switch 240 to close, outputting a contact closure status signal. When the contact mechanism within the switch module 210 is in the closed state, the mechanical linkage mechanism causes the contacts of the micro switch 240 to open, outputting a contact open status signal. Furthermore, the micro switch 240 can transmit its own mechanical digital status signal (physical DO signal) to the power converter 100 through the physical contact output terminal 232. For example, the micro switch 240 can typically be a relay or a solid-state switch.

[0077] Specifically, when the power converter 100 is configured to operate in off-grid mode, it acquires the on / off state signal output by the micro switch 240 through the physical contact output terminal 232 and determines whether the on / off state signal meets a preset state signal. When it is determined that the on / off state signal output by the micro switch 240 is a contact open state signal, it indicates that the switch module 210 is in a conducting state. Therefore, it is determined that the on / off state signal of the switch module 210 does not meet the preset state signal, and it controls itself to stop outputting power to avoid abnormal grid connection or islanded operation, thereby improving system operational safety. Conversely, when it is determined that the on / off state signal output by the micro switch 240 is a contact closed state signal, it indicates that the switch module 210 is in a disconnected state. Therefore, it is determined that the on / off state signal of the switch module 210 meets the preset state signal, and it controls itself to output power normally.

[0078] Understandably, in this embodiment, the state of the switch module 210 can also be communicated to the power converter 100 via a physical DO (Disconnect / Disconnect) signal. In this embodiment, the on / off state signal of the micro switch 240 is configured to characterize the on / off state signal of the switch module 210. A closed contact signal of the micro switch 240 indicates that the switch module 210 is in an off state, and a closed contact signal indicates that the switch module 210 is in a conducting state. This creates an inverse logical correspondence between the on / off state signals of the micro switch 240 and the switch module 210. Furthermore, when the system is operating in off-grid mode and the digital output cable is accidentally disconnected, since the corresponding interface is in an open circuit state, its level signal will be identified by default as the same level as the open state of the micro switch 240 contacts. Under the reverse logic configuration of this application, this level corresponds exactly to the on (closed) state of the switch module 210. Thus, even if the disconnection of the digital output cable causes communication interruption, the system can still determine the actual on / off state of the switch module 210 based on the interface default level and the preset reverse logic rules, solving the problem of misjudgment of state caused by cable disconnection, and improving the operational reliability and status monitoring accuracy of the power switching equipment 200 under off-grid conditions.

[0079] It should be noted that the physical contact output terminal 232 is a bidirectional hardware signal port, which can not only output the on / off status signal of the micro switch 240 to the power converter 100, but also receive the physical control signal input by the power converter 100 to realize hardware interlocking control.

[0080] Please continue reading. Figure 3 The power switching device 200 also includes a power switch, an unlock button, a trip unit, an energy storage capacitor, and a DC-DC converter (DCDC). The unlock button is used to release the system from its locked state, including but not limited to fault lockout and manual lockout. Only after unlocking can the system respond to on / off switching operations and automatic control commands. The trip unit is connected to the control module. When the control module detects a tripping command transmitted through external communication or a circuit fault (such as grid overvoltage), it outputs a trip control signal to drive the trip unit to forcibly disconnect the main circuit where the switching module 210 is located, providing safety protection. The power supply within the electrical control device, i.e., the power supply to the control module, can be controlled via the power switch. After the power switch is turned on, power can be supplied to the control module normally. The energy storage capacitor is connected to the power supply circuit for energy storage and voltage stabilization, suppressing grid voltage fluctuations and compensating for transient output insufficiency of the switching power supply, ensuring stable and continuous system power supply. The DC-DC converter (DCDC) is connected to the power switch and is used to further step down and stabilize the DC voltage output from the switching power supply to 5V / 3.3V, providing a suitable operating power supply for the control module (MCU) and its internal circuits.

[0081] In some embodiments, when the power switching device 200 is powered by the voltage source network 300 and the power converter 100, the preset target signal includes at least one of the electrical signal of the second connection terminal 212 and the on / off state signal of the switching module 210.

[0082] Understandably, since the power switching device 200 can be continuously powered by the power converter 100 under off-grid conditions, it can maintain normal operation and thus interact normally with the power converter 100 through the communication terminal 231, and simultaneously interact with the power converter 100 through the physical contact output terminal 232. Accordingly, the power converter 100 is configured to: determine whether a preset target signal meets preset conditions based on the data exchanged through the communication terminal 231 or the data exchanged through the physical contact output terminal 232; if either signal is determined not to meet the preset conditions, the power converter 100 will stop outputting power.

[0083] In some embodiments, when the power switching device 200 is powered by the voltage source network 300, the preset target signal includes the on / off status signal of the switching module 210.

[0084] Understandably, when the power converter 100 is operating in an off-grid state, a power outage in the voltage source network 300 will cause the power switching device 200 to lose its normal operating power supply, making it unable to interact with the power converter 100 via the communication terminal 231. It can only interact with the power converter 100 via hardware signals through the physical contact output terminal 232. Accordingly, the power converter 100 is configured to: determine whether a preset target signal meets preset conditions based on the on / off status signal of the switch module 210 interacting with the physical contact output terminal 232; when the signal does not meet the preset conditions, the power converter 100 stops outputting power.

[0085] In some embodiments, the power converter 100 is also configured to operate in off-grid mode, and to stop outputting power if communication between the power switching device 200 and the power converter 100 is interrupted for more than a preset duration.

[0086] It is important to understand that the communication between the power switching device 200 and the power converter 100 includes valid heartbeat signals and communication data packets exchanged through the communication terminal 231. A valid heartbeat signal refers to a verification signal periodically exchanged between the power switching device 200 and the power converter 100 according to a preset period and format, used to indicate that the communication link is normal and the equipment is in normal operating condition. Only when the communication terminal 231 receives a heartbeat signal that conforms to the preset format, preset period, and is correctly verified can it be determined as a valid heartbeat signal, confirming that the communication link between the two parties is connected and that the equipment has not experienced abnormal offline, crash, or communication interruption. Communication data packets refer to data messages carrying actual control information and status information exchanged between the power switching device 200 and the power converter 100, including but not limited to the on / off status information of the switch module 210, electrical parameter information of the second connection terminal 212, fault information, control commands, and status update commands. Communication data packets are used to realize parameter transmission, status synchronization, and coordinated control between the two parties.

[0087] Specifically, in the communication link, both devices are equipped with heartbeat signal detection modules to monitor whether the communication is normal. Under normal communication conditions, the power converter 100 and the grid-connected / off-grid switching switch exchange heartbeat signals at set time intervals (e.g., every 5 seconds). If a valid heartbeat signal or communication data packet is not received from the other party within a preset time (e.g., 30 seconds), it is determined that there is a risk of communication interruption. At this time, the power converter 100 will initiate a self-protection process, actively disconnecting the internal relay and stopping the output power. At the same time, the power switching device 200 can also independently determine the communication abnormality and trigger local power outage protection. The protection logic triggered by the communication abnormality can be described by the following formula: Tloss > Tthreshold; where Tloss is the duration of the communication interruption and Tthreshold is the set communication interruption threshold time. After the protection is triggered, the system will enter a fault state and can notify the operator through audible and visual alarms, mobile APP push notifications, or LCD screen prompts.

[0088] Understandably, this application effectively solves the problem in existing technologies where the lack of a reliable self-protection mechanism in the event of communication anomalies leads to the system's inability to respond promptly to abnormal states after communication feedback is lost. This application automatically triggers power outage protection when a communication anomaly is detected and continues for more than the preset communication interruption duration by setting a pre-defined communication interruption time. This ensures that even in the event of communication failure, disconnection, or data anomaly, the power grid side can still safely and reliably disconnect. Furthermore, this application offers a faster response and more reliable protection logic, significantly improving the operational safety and stability of the power switching system under grid-connected, off-grid, and abnormal operating conditions.

[0089] The following specific embodiment illustrates the workflow of the power system in this application.

[0090] Taking the electrical signal, including the voltage signal, at the second connection terminal 212 as an example, the power switching device 200 is connected to the main control unit of the power converter 100 via an RS485 bus, using the Modbus RTU format as the communication protocol. The power switching device 200 can acquire the phase voltage Ugrid from the grid side via sensors or sampling circuits. The communication cycle is 0.5 seconds, and each communication includes information such as the switch status byte, the effective voltage value, and a checksum. After receiving the voltage signal, the main control unit of the power converter 100 performs the following judgment: If the power converter 100 is operating in off-grid mode but detects Ugrid > 36V, it is determined that there is an abnormal voltage on the grid side, and the power converter 100 stops outputting power. If the power converter 100 is operating in grid-connected mode, the system is already in normal grid-connected operation and no additional processing is required; the power converter 100 outputs power normally. If the communication interruption time exceeds 5 seconds, the power converter 100 will immediately stop outputting power regardless of the state of the switch module 210. Subsequently, the main control unit of the power converter 100 writes the fault status to local storage and uploads the fault information through the communication module.

[0091] In some embodiments, the power converter 100 is further configured to operate in off-grid mode and output power normally when the preset target signal meets preset conditions.

[0092] As is understandable, the conditions under which the preset target signal meets the preset conditions can be referred to the previously described content, and will not be repeated here. It should be noted that after the power converter 100 stops outputting power, it will only resume off-grid operation if the switch module 210 is in the open state, communication is restored to normal, and there is no abnormal power supply on the grid side. Furthermore, when the power converter 100 is operating in grid-connected mode, the system is already in normal grid-connected operation, requiring no additional processing, and the power converter 100 outputs power normally.

[0093] This application provides a power system to address the safety hazard of accidental energization of the grid side due to abnormal closure of the grid-connected / off-grid switching switch or communication interruption in related technologies. By establishing a bidirectional communication link between the power converter 100 and the power switching device 200, the system can dynamically sense the status of the switching module 210 and acquire grid-side electrical parameters in real time, thereby responding quickly in abnormal situations, ensuring safe power outage on the grid side, improving overall safety, and meeting relevant grid connection standards.

[0094] Specifically, when the switch module 210 within the power switching device 200 is abnormally closed due to a fault or misoperation, the power converter 100 obtains key parameters such as voltage and current from the grid side in real time through the communication link and actively determines whether the grid is in an unexpected energized state. Once energization is detected in the grid, the power converter 100 will immediately control the internal relay to disconnect, cut off energy output, and enter a fault or standby state, thereby preventing possible electric shock accidents. For communication link failures, the system presets a communication interruption threshold time; if effective signal exchange is not completed or the heartbeat signal is lost within the set time, the system will determine that communication is abnormal, actively perform an output disconnection operation, and report the fault through audible and visual alarms, mobile APP push notifications, or local display, ensuring that grid-side safety isolation can still be forcibly achieved even in the event of communication failure.

[0095] This solution introduces an intelligent protection mechanism based on communication feedback, overcoming the limitations of traditional solutions that rely on physical isolation and manual intervention. This application achieves real-time sensing of switch status and dynamic acquisition of grid parameters, enabling millisecond-level proactive power-off protection when a switch abnormally closes due to internal short circuits or other reasons, with a response speed far superior to traditional methods. Simultaneously, by setting a communication interruption threshold, this system can still autonomously trigger protection in the event of a communication link failure, eliminating protection blind spots in related solutions. Furthermore, this mechanism is primarily implemented through software and communication protocols, eliminating the need for additional hardware detection modules, reducing system cost and maintenance complexity, and is compatible with multiple communication protocols such as RS485, CAN, and Wi-Fi, possessing good scalability and applicability. Its intelligent control method also reduces reliance on manual operation and mechanical interlocks, improving the system's automation level and operational reliability.

[0096] In summary, this application systematically solves the safety risks of grid-side energization caused by switch malfunctions or communication interruptions by constructing a communication sensing and autonomous protection mechanism between the power converter 100 and the grid-connected / off-grid switching switch. While significantly improving system safety and reliability, it also takes into account cost and ease of use, and has broad application prospects.

[0097] This application also provides an islanding protection method, applied to the power system as described in the above embodiments. The islanding protection method includes: When the power converter 100 is operating in off-grid mode and the preset target signal does not meet the preset conditions, the power output will stop.

[0098] It is important to understand that in the islanding protection method, the power converter 100 stops outputting power when it is operating in off-grid mode and the preset target signal does not meet the preset conditions. The specific process can be found in the preceding description and will not be repeated here.

[0099] Understandably, this application also provides an islanding protection method, which is applied to the above-mentioned power system. It can specifically solve the safety hazards of untimely islanding protection response, lack of effective self-protection measures when communication is abnormal, and easy to cause accidental energization of the grid side during off-grid operation. By clarifying the core protection logic of the power converter 100 in off-grid mode, that is, when the preset target signal does not meet the preset conditions, the power output is immediately stopped, thus realizing fast and reliable protection in the islanding state. This method relies on the dual signal interaction mechanism of the communication terminal 231 and the physical contact output terminal 232 in the power system. It can flexibly determine the protection conditions based on communication data or hardware contact signals according to different power supply scenarios of the power switching device 200. This ensures the accuracy of coordinated control under normal operating conditions, and also ensures that the power converter 100 stops power output in time under extreme scenarios such as communication interruption and power supply abnormality, avoiding safety accidents caused by accidental energization on the grid side. At the same time, this method does not require additional hardware detection modules and can be implemented based on the existing system structure, effectively reducing protection costs and maintenance complexity, improving the safety, reliability and automation level of the power system's off-grid operation, meeting the relevant grid connection standards, and further improving the islanding protection system of the power system.

[0100] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0101] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A power system, characterized in that, include: A power converter (100) and a power switching device (200) are provided. The power switching device (200) includes a switching module (210) and an electrical signal sampling module (220). The switching module (210) includes a first connection terminal (211) and a second connection terminal (212). The first connection terminal (211) is electrically connected to the power converter (100), and the second connection terminal (212) is used to electrically connect to a voltage source network (300). The switching module (210) is configured to switch the on / off state between the power converter (100) and the voltage source network (300). The electrical signal sampling module (220) is configured to collect the electrical signal of the second connection terminal (212). The power switching device (200) further includes a signal transmission terminal (230), which is electrically connected to the power converter (100). The power switching device (200) is configured to transmit a preset target signal to the power converter (100) through the signal transmission terminal (230). The power converter (100) is configured to operate in off-grid mode, and stops outputting power when the preset target signal does not meet the preset conditions.

2. The power system according to claim 1, characterized in that, The preset target signal includes at least one of the electrical signal of the second connection terminal (212) and the on / off state signal of the switch module (210); The power converter (100) is configured to determine that the preset target signal does not meet preset conditions, including: It is determined that the electrical signal of the second connection terminal (212) does not meet the preset electrical signal threshold range, and / or it is determined that the on / off state signal of the switch module (210) does not meet the preset state signal.

3. The power system according to claim 2, characterized in that, The electrical signal sampling module (220) includes a voltage acquisition unit (221), which is used to acquire the voltage signal of the second connection terminal (212); The power converter (100) is configured to determine that the electrical signal at the second connection terminal (212) does not meet a preset electrical signal threshold range, including: It is determined that the voltage signal of the second connection terminal (212) is greater than the preset voltage signal.

4. The power system according to claim 2, characterized in that, The electrical signal sampling module (220) includes a current acquisition unit (222), which is used to acquire the current signal of the second connection terminal (212); The power converter (100) is configured to determine that the electrical signal at the second connection terminal (212) does not meet a preset electrical signal threshold range, including: It is determined that the current signal of the second connection terminal (212) is greater than the preset current signal.

5. The power system according to claim 2, characterized in that, The electrical signal sampling module (220) includes a frequency acquisition unit (223), which is used to acquire the voltage frequency signal of the second connection terminal (212); The power converter (100) is configured to determine that the electrical signal at the second connection terminal (212) does not meet a preset electrical signal threshold range, including: It is determined that the voltage frequency signal of the second connection terminal (212) is greater than the preset voltage frequency signal.

6. The power system according to claim 2, characterized in that, The on / off state signals of the switch module (210) include an off state signal and an on state signal; The power converter (100) is configured to determine that the on / off state signal of the switching module (210) does not satisfy a preset state signal, including: The on / off state signal of the switch module (210) is determined to be an off signal.

7. The power system according to claim 6, characterized in that, The signal transmission terminal (230) includes a communication terminal (231) and a physical contact output terminal (232). The communication terminal (231) is configured to transmit electrical signals of the second connection terminal (212) to the power converter (100), and the physical contact output terminal (232) is configured to transmit on / off status signals of the switch module (210) to the power converter (100).

8. The power system according to claim 7, characterized in that, The power switching device (200) further includes a micro switch (240) connected between the switch module (210) and the physical contact output terminal (232). The on / off state signal of the micro switch (240) is configured to characterize the on / off state signal of the switch module (210). When the on / off state signal of the micro switch (240) is a contact closed state signal, the switch module (210) is in an open state signal; when the on / off state signal of the micro switch (240) is a contact open state signal, the switch module (210) is in a conducting state. The power converter (100) is configured to determine that the on / off state signal of the switching module (210) is an off signal, including: The on / off state signal of the micro switch (240) is determined to be the contact open state signal.

9. The power system according to claim 7, characterized in that, When the power switching device (200) is powered by the voltage source network (300), the preset target signal includes the on / off status signal of the switching module (210).

10. The power system according to claim 1, characterized in that, The power converter (100) is also configured to operate in off-grid mode, and to stop outputting power if communication between the power switching device (200) and the power converter (100) is interrupted for more than a preset time.

11. The power system according to claim 1, characterized in that, The power converter (100) is also configured to operate in off-grid mode and to output electrical energy normally when the preset target signal meets the preset conditions.

12. An islanding protection method, applied to the power system as described in any one of claims 1 to 11, characterized in that, The method includes: When the power converter (100) is operating in off-grid mode and the preset target signal does not meet the preset conditions, the power converter (100) stops outputting electrical energy.

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