CN115718255A

CN115718255A - Detection circuit, detection method, detection device, energy storage system and readable storage medium

Info

Publication number: CN115718255A
Application number: CN202211422230.8A
Authority: CN
Inventors: 鲁力; 吴志敢; 王龙飞
Original assignee: Hiconics Eco Energy Technology Co ltd; Midea Welling Motor Technology Shanghai Co Ltd
Current assignee: Hiconics Eco Energy Technology Co ltd; Midea Welling Motor Technology Shanghai Co Ltd
Priority date: 2022-11-14
Filing date: 2022-11-14
Publication date: 2023-02-28

Abstract

The invention provides a detection circuit, a detection method, a detection device, an energy storage system and a readable storage medium. The detection circuit includes: resistance component, switching piece and controlling means. The switch and the resistor component are connected in series between the output end of the direct current bus and the grounding end; the control device is connected with the first relay assembly and the switch member. The control device is used for: when the first relay assembly is in the off state, the control switch piece is switched from the off state to the on state; acquiring a first voltage difference value when the switching element is in a disconnected state and a second voltage difference value when the switching element is in a connected state, wherein the first voltage difference value and the second voltage difference value are both voltage difference values between a first end and a second end of the first relay assembly; and determining a fault state of the first relay assembly according to the first voltage difference value and the second voltage difference value.

Description

Detection circuit, detection method, detection device, energy storage system and readable storage medium

Technical Field

The invention belongs to the technical field of energy storage converters, and particularly relates to a detection circuit, a detection method, a detection device, an energy storage system and a readable storage medium.

Background

In order to improve the use safety of the household energy storage converter, the output end of the energy storage converter and the power grid end need to be electrically isolated through a relay, namely, the relay is arranged between the power grid live wire and zero line and the output end of the energy storage converter. Before the energy storage converter is connected to the grid, whether the relay has a fault or not needs to be detected.

In the related technology, whether the relay has faults or not is detected through circuit design, the hardware setting is complex, and the detection cost is high.

Disclosure of Invention

The present invention has been made to solve one of the technical problems occurring in the prior art or the related art.

To this end, a first aspect of the invention proposes a detection circuit.

A second aspect of the invention proposes a detection method.

A third aspect of the invention provides a detection apparatus.

A fourth aspect of the invention provides a detection assembly.

A fifth aspect of the invention proposes a readable storage medium.

A sixth aspect of the present invention provides an energy storage system.

In view of the above, according to a first aspect of the present invention, a detection circuit for detecting a fault condition of a first relay assembly between a neutral line of a dc bus of an energy storage converter and a neutral line of a three-phase power supply is provided, the detection circuit comprising: a resistor assembly, a switching element and a control device. The switch and the resistance component are connected in series between the output end of the direct current bus and the grounding end; the control device is respectively connected with the first relay assembly and the switch piece.

The control device is used for: when the first relay assembly is in the off state, the control switch piece is switched from the off state to the on state; acquiring a first voltage difference value when the switching element is in an off state and a second voltage difference value when the switching element is in an on state, wherein the first voltage difference value and the second voltage difference value are both voltage difference values between a first end and a second end of the first relay assembly; and determining a fault state of the first relay assembly according to the first voltage difference value and the second voltage difference value.

The invention provides a detection circuit of an energy storage converter. And an electric appliance is isolated between a neutral line of a direct current bus of the energy storage converter and a zero line of a three-phase power supply through a first relay assembly. When the energy storage converter works in a grid-connected mode, the first relay assembly between the neutral line of the direct current bus of the energy storage converter and the zero line of the three-phase power supply is controlled to be disconnected, the energy storage converter and the power grid are guaranteed not to be electrically connected on the zero line, and potential safety hazards are avoided.

The first relay assembly comprises at least two relays, when the first relay assembly is controlled to be in grid-connected operation, all relays in the first relay assembly are controlled to be in a disconnected state, two ends of the first relay assembly are guaranteed not to be in a connected state, under the condition of partial faults in at least two relays in the first relay assembly, the neutral line of a direct current bus of the energy storage converter can still be guaranteed to be isolated from the neutral line of a three-phase power supply, and the isolation effect of the relay assembly is better than that of a single relay.

The detection circuit comprises a resistance component, a switch piece and a control device, wherein the resistance component is connected with the switch piece in series, and the resistance component and the switch piece which are connected in series are connected between the output end of the direct current bus and the grounding end.

The control device is connected with the switch piece and can control the on-off state of the switch piece. The control device is further connected with the first relay assembly and can control the on-off state of the first relay assembly.

When the control device controls the first relay assembly to be in the off state, each relay in the first relay assembly needs to be controlled to be in the off state, and the first relay assembly is ensured to be in the complete off state. The control device controls the first relay assembly to be in a conducting state, and each relay in the first relay assembly needs to be controlled to be in the conducting state.

The control device can switch the on-off state between the output end of the direct current bus and the grounding end by switching the on-off state of the switch piece. Whether adhesion fault exists in the first relay assembly or not is controlled by the control device to detect, the on-off state is switched by controlling the switch piece, voltage difference values at two ends of the first relay assembly before and after the on-off state is switched by the switch piece are obtained, and whether the first relay assembly has the fault or not can be accurately judged based on the voltage difference values before and after the on-off state is switched.

Before the energy storage converter is incorporated into the power networks, whether there is adhesion fault detection to first relay assembly through controlling means, the testing process that detects first relay assembly specifically as follows:

in the initial detection stage, the control switch part and the first relay assembly are both in an off state, and a first voltage difference value at two ends of the first relay assembly is detected. Whether the first relay has a fault or not can be preliminarily judged based on the first voltage difference value. Under the condition that the first voltage difference value is small, it is determined that the two ends of the first relay assembly are possibly in a conducting state, and due to the design of a grounding system of the energy storage converter, the situation that the voltage values at the two ends of the first relay assembly are close to 0 possibly exists at the moment, so that the control switch piece is switched to the conducting state, and the second voltage values at the two ends of the first relay assembly are detected. After the switch is switched on, the resistor assembly is connected between the output end of the direct current bus and the grounding system, so that the voltage value of one end, close to the neutral line of the direct current bus, of the first relay assembly is changed, and at the moment, if the second voltage difference value of the two ends of the first relay assembly is smaller, it can be determined that the first relay assembly has a fault.

It should be noted that, because the first relay assembly includes at least two relays, and the first relay assembly is in the off state, which is the state in which all relays are in the off state, it can be determined that there is at least one relay with a sticking fault in the first relay assembly.

According to the invention, the resistor component and the switch component are arranged in series between the output end and the grounding end of the direct current bus of the energy storage converter, the first voltage difference value at the two ends of the first relay component is detected before the switch component is controlled to be switched on, the second voltage difference value at the two ends of the first relay component is detected after the switch component is controlled to be switched on, and whether the first relay component has the adhesion fault or not can be accurately determined according to the first voltage difference value and the second voltage difference value. Through the on-off state of change over switch spare, can control whether resistance assembly inserts between direct current bus's output and earthing terminal to adjust the voltage value that first relay subassembly is close to direct current bus one end, avoided having the false retrieval of adhesion trouble to first relay subassembly.

The detection circuit only comprises the resistor component and the switch component, and is matched with the control logic to realize accurate detection on whether the first relay component has the adhesion fault.

In addition, according to the detection circuit in the above technical solution provided by the present invention, the following additional technical features may be further provided:

in the above technical solution, the first relay assembly includes: the three-phase power supply comprises a first relay and a second relay, wherein the first relay and the second relay are connected in series, one end of the first relay is connected with a neutral line of a direct current bus, and one end of the second relay is connected with a zero line of a three-phase power supply;

the first relay assembly being in the open state includes: the first relay is in an off state, and the second relay is in an on state; or the second relay is in an off state and the first relay is in an on state.

In this technical scheme, first relay subassembly includes two relays, is first relay and second relay respectively. The first relay is connected in series with the second relay. The first end of the first relay is used as the first end of the first relay assembly and is connected with a neutral line of a direct current neutral line. And the second end of the second relay is used as the second end of the first relay component and is connected with a zero line of the three-phase power supply. The second end of the first relay is connected with the first end of the second relay.

The first relay assembly being in the open state includes any one of: the first relay is in an off state and the second relay is in an on state. The first relay is in an on state and the second relay is in an off state. The first relay and the second relay are both in an off state.

Because the first relay and the second relay in the first relay assembly are connected in series, the first relay assembly is in an off state if there is a relay in the off state in the first relay and the second relay.

It should be noted that, in the process of detecting whether the first relay assembly has a fault, by controlling any one of the first relay and the second relay to be in the off state, it is possible to detect whether the first relay or the second relay in the off state has an adhesion fault.

Through set up the first relay and the second relay of series connection in first relay subassembly in this scheme, can guarantee that energy storage converter operation is in the electrical isolation state under the state of being incorporated into the power networks between direct current bus and the three phase current source, compare in the scheme that only sets up a single relay between direct current bus and three phase current source, have higher isolation stability.

In any of the above technical solutions, the control device determines the fault state of the first relay assembly according to the first voltage difference value and the second voltage difference value, and is specifically configured to:

and determining that a target relay in the first relay assembly is in a fault state based on the first voltage difference value and the second voltage difference value which are both smaller than a preset threshold value, wherein the target relay is a relay in a disconnection state in the first relay and the second relay.

In this technical scheme, first voltage difference is that the voltage difference between the first relay subassembly both ends that detect is under switch member and the first relay subassembly and all is in the off-state. The second voltage difference value is a voltage difference value between two ends of the first relay assembly detected when the switch is in a conducting state and the first relay assembly is in a disconnecting state.

Due to the design of a grounding system (PE) in the energy storage converter system, the possibility of misjudgment can exist only according to the fact that whether the first relay assembly has fault detection or not and the possibility of misjudgment exists only according to the first voltage difference value or the second voltage difference value, and whether the resistance assembly is connected between the negative pole of the direct current bus and the grounding system or not is adjusted through the on-off state of the switch piece, so that the possibility of misjudgment can be effectively avoided.

In some possible embodiments, in the case that the second relay is in the on state by controlling the first relay to be in the off state, whether the first relay controlled to be off has a fault can be detected according to the detected first voltage difference value and the detected second voltage difference value. And under the condition that the first voltage difference value and the second voltage difference value are both smaller than a preset threshold value, judging that the first relay is in an adhesion fault state.

In some possible embodiments, in a case where the first relay is in the on state by controlling the second relay to be in the off state, whether there is a fault in the second relay that is controlled to be off can be detected based on the detected first voltage difference value and the detected second voltage difference value. And under the condition that the first voltage difference value and the second voltage difference value are both smaller than a preset threshold value, judging that the second relay is in an adhesion fault state.

In some possible embodiments, when both the first relay and the second relay are controlled to be in the off state and both the first voltage difference value and the second voltage difference value are smaller than a preset threshold value, it is determined that a relay in the stuck fault state exists in the first relay and the second relay.

According to the scheme, one relay in the first relay assembly is controlled to be disconnected, the other relay is kept on, whether the relay in the disconnected state is in the fault state or not can be accurately detected according to the first voltage difference value and the second voltage difference value, and the effect of accurately positioning the fault of the first relay assembly is achieved.

In any of the above technical solutions, a second relay assembly is arranged between a three-phase input end of the energy storage converter and a three-phase power supply; the control device is connected with the second relay assembly;

before the control switch member is switched from the off state to the on state when the first relay assembly is in the off state, the control device is further configured to: and controlling the second relay assembly to be in an off state.

In the technical scheme, the second relay assembly is used for controlling the on-off state between the three-phase input end of the energy storage converter and the three-phase power supply.

The second relay assembly includes three sets of relays, each set of relays having a number of at least two. The first ends of the three groups of relays are respectively connected with the three-phase input end of the energy storage converter, and the second ends of the three groups of relays are connected to a three-phase power supply.

In the process of detecting whether the first relay assembly has faults through the detection circuit, the energy storage converter is not in a grid-connected state, and the second relay assembly is in a disconnected state, namely, the three-phase power supply and the energy storage converter are in the disconnected state, so that the detection accuracy is improved, and the faults caused by the fact that the energy storage converter is connected into the three-phase power supply before whether the first relay has the faults are not determined are avoided.

In any of the above solutions, the detection circuit further includes a capacitive component. The capacitive component is arranged between the three-phase input end of the energy storage converter and the first relay component.

In the technical scheme, the capacitive component for filtering is arranged between the three-phase input end of the energy storage converter and the first relay component, so that the stability of grid-connected operation of the energy storage converter is improved.

The capacitive component comprises a first capacitor, a second capacitor and a third capacitor.

In any of the above technical solutions, the detection circuit further includes a first detection element and a second detection element.

The first detection piece is arranged at the first end of the first relay assembly and used for collecting a voltage value of the first end of the first relay assembly; the second detection piece is arranged at the second end of the first relay assembly and used for collecting the voltage value of the second end of the first relay assembly.

In this technical scheme, the sampling end of first detection piece is connected with the first end of first relay subassembly, and first detection piece can detect the magnitude of voltage of the first end of first relay subassembly. The sampling end of the second detection piece is connected with the second end of the first relay assembly, and the second detection piece can detect the voltage value of the second end of the first relay assembly.

The first detection piece and the second detection piece are connected with the control device, and after the first detection piece and the second detection piece acquire voltage values of the first end and the second end of the first relay assembly, the acquired voltage values of the first end and the second end of the first relay assembly are transmitted to the control device. The control device can carry out difference value calculation according to the voltage values of the first end and the second end of the first relay assembly to obtain a first voltage difference value or a second voltage difference value.

For example, the first detection element, the second detection element and the control device can be provided integrally.

According to the scheme, the first detection part and the second detection part are respectively arranged at the first end and the second end of the first detection assembly, so that the voltage values of the first end and the second end of the first relay assembly can be accurately detected, and the accuracy of the calculated first voltage difference value and the second voltage difference value is guaranteed.

According to a second aspect of the present invention, there is provided a detection method for the detection circuit in the first aspect, the detection method comprising:

when the first relay assembly is in the off state, the control switch piece is switched from the off state to the on state;

acquiring a first voltage difference value when the switching element is in an off state and a second voltage difference value when the switching element is in an on state, wherein the first voltage difference value and the second voltage difference value are both voltage difference values between a first end and a second end of the first relay assembly;

and determining a fault state of the first relay assembly according to the first voltage difference value and the second voltage difference value.

In the technical scheme, at the beginning of detection, the control switch and the first relay assembly are both in an off state, and a first voltage difference value at two ends of the first relay assembly is detected. Whether the first relay has a fault or not can be preliminarily judged based on the first voltage difference value. Under the condition that the first voltage difference value is small, it is determined that the two ends of the first relay assembly are possibly in a conducting state, and due to the design of a grounding system of the energy storage converter, the situation that the voltage values at the two ends of the first relay assembly are close to 0 possibly exists at the moment, so that the control switch piece is switched to the conducting state, and the second voltage values at the two ends of the first relay assembly are detected. After the switch is switched on, the resistor assembly is connected between the output end of the direct current bus and the grounding system, so that the voltage value of one end, close to the neutral line of the direct current bus, of the first relay assembly is changed, and at the moment, if the second voltage difference value of the two ends of the first relay assembly is smaller, it can be determined that the first relay assembly has a fault.

In the above technical solution, the first relay assembly includes a first relay and a second relay;

the first relay assembly being in the open state includes: the first relay is in an off state; and/or the second relay is in an open state.

In this technical scheme, first relay subassembly includes two relays, is first relay and second relay respectively. The first relay is connected in series with the second relay. The first end of the first relay is used as the first end of the first relay assembly and is connected with a neutral line of a direct current neutral line. And the second end of the second relay is used as the second end of the first relay assembly and is connected with a zero line of a three-phase power supply. The second end of the first relay is connected with the first end of the second relay.

Through set up first relay and the second relay of establishing ties in first relay subassembly in this scheme, can guarantee that energy storage converter operates and be in the electrical isolation state between direct current bus and the three phase current under the state of being incorporated into the power networks, compare in only setting up the scheme of a single relay between direct current bus and three phase current, have higher isolation stability.

In any of the above technical solutions, determining the fault state of the first relay assembly according to the first voltage difference value and the second voltage difference value includes:

Due to the design of the grounding system (PE) in the energy storage converter system, the possibility of misjudgment is possible only according to the first voltage difference value or the second voltage difference value to judge whether the first relay assembly has fault detection, and the possibility of misjudgment can be effectively avoided by switching the on-off state of the switch piece to adjust whether the resistance assembly is connected between the negative pole of the direct current bus and the grounding system.

In any of the above technical solutions, a second relay assembly is arranged between a three-phase input end of the energy storage converter and a three-phase power supply;

when first relay subassembly is in the off-state, before the control switch spare switches to the conducting state by the off-state, still include: and controlling the second relay assembly to be in an open state.

The second relay assembly includes three sets of relays, and the number of each set of relays is at least two. The first ends of the three groups of relays are respectively connected with the three-phase input end of the energy storage converter, and the second ends of the three groups of relays are connected to a three-phase power supply. And the three groups of relays are respectively used for controlling the on-off state between the three-phase input end of the energy storage converter and the three-phase power supply.

In the process of detecting whether the first relay assembly has a fault through the detection circuit, the energy storage converter is not in a grid-connected state, and the second relay assembly is in a disconnected state, namely, the three-phase power supply and the energy storage converter are in the disconnected state, so that the detection accuracy is improved, and the fault caused by the fact that the energy storage converter is connected into the three-phase power supply before whether the first relay assembly has the fault is not determined is avoided.

In any one of the above technical solutions, obtaining a first voltage difference value when the switching element is in an off state and a second voltage difference value when the switching element is in an on state includes:

when the switch piece is in an off state, acquiring a first voltage value of a first end of the first relay assembly and a second voltage value of a second end of the first relay assembly; determining a first voltage difference value according to the first voltage value and the second voltage value; when the switch piece is in a conducting state, acquiring a first end and a third voltage value of the first relay assembly and a fourth voltage value of a second end of the first relay assembly; and determining a second voltage difference value according to the third voltage value and the fourth voltage value.

In this technical solution, the detection circuit further includes a first detection element and a second detection element.

The first detection piece is arranged at the first end of the first relay assembly and used for collecting the voltage value of the first end of the first relay assembly; the second detection piece is arranged at the second end of the first relay assembly and used for collecting the voltage value of the second end of the first relay assembly.

According to a third aspect of the present invention, there is provided a detection apparatus for the detection circuit in the first aspect, the detection apparatus comprising:

the control module is used for controlling the switch piece to be switched from the off state to the on state when the first relay assembly is in the off state;

the acquisition module is used for acquiring a first voltage difference value when the switching element is in an off state and a second voltage difference value when the switching element is in an on state, wherein the first voltage difference value and the second voltage difference value are both voltage difference values between a first end and a second end of the first relay assembly;

and the determining module is used for determining the fault state of the first relay assembly according to the first voltage difference value and the second voltage difference value.

According to a fourth aspect of the present invention there is provided a detection assembly comprising: a memory having a program or instructions stored therein; the processor, which executes the program or the instruction stored in the memory to implement the steps of the detection method in any one of the second technical solutions, thus having all the beneficial technical effects of the detection method in any one of the second technical solutions described above, and not being described in detail herein.

According to a fifth aspect of the present invention, a readable storage medium is provided, on which a program or instructions are stored, and the program or instructions, when executed by a processor, implement the steps of the detection method according to any one of the above-mentioned second aspects. Therefore, all the beneficial technical effects of the detection method in any technical solution of the second aspect are achieved, and are not described in detail herein.

According to a sixth aspect of the present invention, there is provided an energy storage system comprising: the detection apparatus defined in the third aspect, and/or the detection assembly defined in the fourth aspect, and/or the readable storage medium defined in the fifth aspect, thus having all the advantages of the detection apparatus defined in the third aspect, and/or the detection apparatus defined in the fourth aspect, and/or the readable storage medium defined in the fifth aspect, and will not be described in detail herein.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 shows a circuit diagram of a detection circuit provided in one embodiment of the present invention;

FIG. 2 shows a block diagram of a detection circuit provided in one embodiment of the present invention;

FIG. 3 shows one of the schematic flow diagrams of the detection method provided in one embodiment of the invention;

FIG. 4 shows a second schematic flow chart of a detection method provided in an embodiment of the invention;

FIG. 5 shows a block diagram of a detection apparatus provided in an embodiment of the present invention;

FIG. 6 illustrates a block diagram of a detection component provided by one embodiment of the present invention;

fig. 7 shows a block diagram of an energy storage system according to an embodiment of the present invention.

Wherein, the correspondence between the reference numbers and the component names in fig. 1 and fig. 2 is:

100 detection circuit, 110 energy storage converter, 112 neutral, 120 first relay assembly, S ₂ First relay, S ₃ Second relay, R ₁ Resistance component, S ₁ Switching element, 130 control device, 140 second relay assembly, 150 capacitive assembly, C ₁ A first capacitor, C ₂ A second capacitor, C ₃ Third capacitance, V ₁ First detecting member, V ₂ Second detection member, 200 three-phase power.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.

Detection circuits, detection methods, devices, energy storage systems, and readable storage media according to some embodiments of the invention are described below with reference to fig. 1-7.

In an embodiment according to the present application, as shown in fig. 1 and 2, a detection circuit 100 for detecting a fault condition of a first relay assembly 120 between a neutral line 112 of a dc bus of a power storage converter 110 and a neutral line of a three-phase power supply 200 is proposed, the detection circuit 100 comprising: resistance component R ₁ Switch member S ₁ And a control device 130. Switch S ₁ And a resistance component R ₁ The DC bus is connected in series between the output end of the DC bus and the grounding end; the control device 130 is connected to the first relay assembly 120 and the switching element S, respectively ₁ Are connected.

The control device 130 is configured to: the switching element S is controlled in an off state of the first relay assembly 120 ₁ Switching from an off state to an on state; obtaining a switch element S ₁ A first voltage difference in the off-state, and a switching element S ₁ A second voltage difference value in the on state, where the first voltage difference value and the second voltage difference value are both voltage difference values between the first end and the second end of the first relay assembly 120; based on the first voltage difference value and the second voltage difference value, a fault condition of the first relay assembly 120 is determined.

The embodiment provides a detection circuit 100 of a storage converter 110. Electrical isolation is provided between the neutral line 112 of the dc bus of the energy storage converter 110 and the neutral line of the three-phase power supply 200 by means of the first relay assembly 120. When the energy storage converter 110 works in a grid-connected mode, the first relay assembly 120 between the neutral line 112 of the direct current bus of the energy storage converter 110 and the zero line of the three-phase power supply 200 is controlled to be disconnected, so that the energy storage converter 110 is not electrically connected with the power grid on the zero line, and potential safety hazards are avoided.

The first relay assembly 120 comprises at least two relays, when the first relay assembly 120 is controlled to operate in a grid-connected mode, all relays in the first relay assembly 120 are controlled to be in an off state, it is guaranteed that two ends of the first relay assembly 120 are not in an on state, under the condition that partial faults occur in the at least two relays in the first relay assembly 120, electrical isolation between a neutral line 112 of a direct current bus of the energy storage converter 110 and a zero line of the three-phase power supply 200 can still be guaranteed, and the isolation effect is better compared with that of a single relay.

The detection circuit 100 includes a resistor element R ₁ Switch member S ₁ And a control device 130, a resistance component R ₁ And a switch element S ₁ Series-connected and series-connected resistor components R ₁ And a switch member S ₁ Connected between the output terminal of the dc bus and the ground terminal.

Wherein the resistance component R ₁ Comprising at least one resistor in a resistor block R ₁ When a plurality of resistors are included, the plurality of resistors are connected in series with each other.

Illustratively, the resistive component R ₁ Is connected with the output end of the DC bus, a resistor component R ₁ Second terminal and switch element S ₁ Is connected to a first end of a switch member S ₁ The second terminal of (a) is grounded.

Illustratively, the switch member S ₁ Is connected with the output end of the DC bus, and a switch element S ₁ Second terminal and resistance component R ₁ Is connected to a resistor component R ₁ The second terminal of (a) is grounded.

Control device 130 and switch element S ₁ Connected, the control means 130 being able to control the switch S ₁ On-off state of (c). The control device 130 is also connected to the first relay assembly 120, and the control device 130 can control the on/off state of the first relay assembly 120.

When the control device 130 controls the first relay assembly 120 to be in the off state, it is necessary to control each relay in the first relay assembly 120 to be in the off state, so as to ensure that the first relay assembly 120 is in the completely off state.

The control device 130 switches the switch member S ₁ The on-off state of the switching circuit can switch the on-off state between the output end of the direct current bus and the grounding end. In the process of detecting whether the first relay assembly 120 has the adhesion fault under the control of the control device 130, the switch part S is controlled ₁ Switching on/off state and obtaining the switch element S ₁ The voltage difference between the two ends of the first relay assembly 120 before and after the on-off state is switched, and based on the voltage difference before and after the on-off state is switched, whether a fault exists in the first relay assembly 120 can be accurately judged.

Before the energy storage converter 110 is connected to the grid, whether the first relay assembly 120 has adhesion fault or not is detected through the control device 130, and the detection process for detecting the first relay assembly 120 is specifically as follows:

at the beginning of the detection phase, the switch element S is controlled ₁ And the first relay assembly 120 are both in an off state, detecting a first voltage difference across the first relay assembly 120. The first relay S can be paired based on the first voltage difference value ₂ And whether a fault exists is preliminarily judged. Under the condition that the first voltage difference is small, it is determined that the two ends of the first relay assembly 120 may be in a conducting state, and due to the design of the grounding system of the energy storage converter 110, there may be a case that the voltage values at the two ends of the first relay assembly 120 are both close to 0, so the switch element S is controlled at this time ₁ And switched to the on state to detect a second voltage across the first relay assembly 120. Switch S ₁ After being conducted, the resistance component R ₁ The voltage value of the end of the first relay assembly 120 near the dc bus neutral 112 is changed by switching between the dc bus output and the ground system, and it can be determined that there is a fault in the first relay assembly 120 if the second voltage difference across the first relay assembly 120 is still small.

It should be noted that, since the first relay assembly 120 includes at least two relays, and the first relay assembly 120 is in the off state, which is a state in which all relays are in the off state, it can be determined that there is at least one relay with sticking fault in the first relay assembly 120.

In the embodiment, the resistor component R is serially arranged between the output end and the ground end of the dc bus of the energy storage converter 110 ₁ And a switch member S ₁ In the control of the switching element S ₁ Before the first relay assembly 120 is turned on, a first voltage difference value between the two ends of the first relay assembly is detected, and a switch element S is controlled ₁ After the relay assembly is conducted, a second voltage difference value at two ends of the first relay assembly 120 is detected, and whether the first relay assembly 120 has the adhesion fault or not can be accurately determined according to the first voltage difference value and the second voltage difference value. By switching the switching member S ₁ Can control the resistance component R ₁ Whether the voltage value of the first relay assembly 120 close to one end of the direct current bus is connected between the output end of the direct current bus and the grounding end, and therefore misdetection of adhesion faults of the first relay assembly 120 is avoided.

The detection circuit 100 in the present embodiment includes only the resistance component R ₁ And a switch member S ₁ And whether the adhesion fault exists in the first relay assembly 120 is accurately detected by matching with a control logic, compared with the prior art that the adhesion fault exists in a complex circuit design, the method has the advantage of low hardware cost, and the hardware cost is reduced while the detection accuracy is ensured.

In addition, according to the detection circuit 100 provided in the present embodiment in the foregoing embodiments, the following additional technical features may also be provided:

as shown in fig. 1 and 2, in the above embodiment, the first relay assembly 120 includes: first relay S ₂ And a second relay S ₃ First relay S ₂ And a second relay S ₃ Are connected in series with a first relay S ₂ Is connected to the neutral line 112 of the dc bus, a second relay S ₃ One end of which is connected with the zero line of the three-phase power supply 200;

the first relay assembly 120 being in the open state includes: first relay S ₂ In an off state, and the second relay S ₃ In a conducting state; or a second relay S ₃ Is in an off state and the first relayDevice S ₂ Is in a conducting state.

In this embodiment, the first relay assembly 120 includes two relays, respectively the first relay S ₂ And a second relay S ₃ . First relay S ₂ And a second relay S ₃ Are connected in series. First relay S ₂ As a first terminal of the first relay assembly 120, is connected to the neutral line 112 of the dc neutral. Second relay S ₃ As a second end of the first relay assembly 120, is connected to the neutral line of the three-phase power supply 200. First relay S ₂ Second terminal and second relay S ₃ Is connected to the first end of the first switch.

The first relay assembly 120 being in the open state includes any one of: first relay S ₂ In the off state, the second relay S ₃ Is in a conducting state. First relay S ₂ In the on state, the second relay S ₃ In the off state. First relay S ₂ And a second relay S ₃ Are all in the off state.

Due to the first relay S in the first relay assembly 120 ₂ And a second relay S ₃ Are connected in series, and therefore, the first relay S ₂ And a second relay S ₃ The first relay assembly 120 is in the open state if there is a relay in the open state.

It should be noted that, in the process of detecting whether the first relay assembly 120 has a fault, the first relay S is controlled ₂ And a second relay S ₃ Can be in an off state, and can be applied to the first relay S in the off state ₂ Or a second relay S ₃ And detecting whether the adhesion fault exists or not.

In the present embodiment, the first relays S are serially connected in the first relay assembly 120 ₂ And a second relay S ₃ The energy storage converter 110 can be ensured to be in an electrical isolation state between the direct current bus and the three-phase power supply 200 in the grid-connected state, and compared with a scheme that only a single relay is arranged between the direct current bus and the three-phase power supply 200And has higher isolation stability.

As shown in fig. 1 and fig. 2, in any of the above embodiments, the control device 130 determines the fault state of the first relay assembly 120 according to the first voltage difference value and the second voltage difference value, and is specifically configured to:

determining that a target relay in the first relay assembly 120 is in a fault state based on the first voltage difference value and the second voltage difference value both being less than a preset threshold, the target relay being a first relay S ₂ And a second relay S ₃ In an open state.

In this embodiment, the first voltage difference is the switching element S ₁ And the voltage difference across the first relay assembly 120, both in the off state of the first relay assembly 120. The second voltage difference is a switching element S ₁ In the on state and the first relay assembly 120 is in the off state, a voltage difference between the two terminals of the first relay assembly 120 is detected.

Due to the design of the grounding system (PE) in the energy storage converter 110 system, there is a possibility of erroneous judgment if the first relay assembly 120 has fault detection only according to the first voltage difference value or the second voltage difference value, but by switching the switching element S ₁ On-off state of (3), adjusting the resistance component R ₁ Whether the direct current bus negative pole and the grounding system are connected or not can effectively avoid the possibility of misjudgment.

In some possible embodiments, the first relay S is controlled ₂ In the off state, the second relay S ₃ Under the condition of on state, according to the detected first voltage difference value and second voltage difference value the first relay S capable of controlling disconnection ₂ Whether a fault exists is detected. Under the condition that the first voltage difference value and the second voltage difference value are both smaller than a preset threshold value, the first relay S is judged ₂ In a stuck fault condition.

In some possible embodiments, the second relay S is controlled ₃ In the off state, the first relay S ₂ In the on state, upon detectionA first voltage difference value and a second voltage difference value, a second relay S capable of controlling the disconnection ₃ Whether a fault exists is detected. Under the condition that the first voltage difference value and the second voltage difference value are both smaller than a preset threshold value, the second relay S is judged ₃ In a stuck fault condition.

In some possible embodiments, the first relay S is controlled ₂ And a second relay S ₃ All are in a disconnected state, and under the condition that the first voltage difference value and the second voltage difference value are both smaller than a preset threshold value, the first relay S is judged ₂ And a second relay S ₃ There is a relay in an stuck fault state.

In this embodiment, one relay is disconnected in the first relay assembly 120 through control, and another relay keeps conducting, and according to first voltage difference and second voltage difference, whether can be in the fault state to the relay that is in the off-state and carry out accurate detection, has realized carrying out the effect of accurate location to the trouble of first relay assembly 120.

As shown in fig. 1 and fig. 2, in any of the above embodiments, a second relay assembly 140 is arranged between the three-phase input end of the energy storage converter 110 and the three-phase power supply 200; the control device 130 is connected with the second relay assembly 140;

the switching element S is controlled in an off state of the first relay assembly 120 ₁ Before switching from the off-state to the on-state, the control device 130 is further configured to: the second relay assembly 140 is controlled to be in an open state.

In this embodiment, the second relay assembly 140 is used to control the on/off state between the three-phase input of the energy storage converter 110 and the three-phase power source 200.

The second relay assembly 140 includes three sets of relays, each set of relays being at least two in number. The first ends of the three sets of relays are respectively connected to the three-phase input end of the energy storage converter 110, and the second ends of the three sets of relays are connected to the three-phase power supply 200.

As shown in FIG. 1, the three sets of relays include A-phase relay S _A1 And relay S _A2 Relaying of phase BDevice S _B1 And relay S _B2 C-phase relay S _C1 And relay S _C2 . Relay S connected in series _A1 And relay S _A2 The phase A in the three-phase power supply 200 can be effectively isolated from the phase A input end of the energy storage converter 110. Relay S connected in series _B1 And relay S _B2 The phase B in the three-phase power supply 200 can be effectively isolated from the phase B input end of the energy storage converter 110. Relays S in series _C1 And relay S _C2 The electric appliance isolation can be effectively carried out between the C phase in the three-phase power supply 200 and the C phase input end of the energy storage converter 110. This embodiment is through all setting up two relays of establishing ties in every group relay, can effectively avoid the problem of the electrical isolation inefficacy that one of them relay became invalid and lead to, has improved the stability of energy storage converter 110 operation.

In the process of detecting whether the first relay assembly 120 has a fault through the detection circuit 100, it needs to be ensured that the energy storage converter 110 is not in a grid-connected state, and the second relay assembly 140 is in a disconnected state, that is, the three-phase power supply 200 and the energy storage converter 110 are in a disconnected state, so that the detection accuracy is improved, and it is avoided that the first relay S is not determined ₂ Before the fault exists, the energy storage converter 110 is connected to the fault caused by the three-phase power supply 200.

In any of the above embodiments, the detection circuit 100 further comprises a capacitive element 150, as shown in fig. 1 and 2. The capacitive element 150 is disposed between the three-phase input terminal of the energy storage converter 110 and the first relay element 120.

In this embodiment, the capacitive component 150 for filtering is disposed between the three-phase input end of the energy storage converter 110 and the zero line of the three-phase power supply 200, so as to improve the stability of grid-connected operation of the energy storage converter 110.

The capacitive element 150 comprises a first capacitor C ₁ A second capacitor C ₂ And a third capacitance C ₃ 。

As shown in fig. 1, a first capacitor C ₁ Is connected between phase a of the three-phase power supply 200 and the first relay assembly 120, and a second capacitor C ₂ Is connected toA third capacitor C between phase B and the first relay assembly 120 in the three-phase power supply 200 ₃ Is connected between phase C and the first relay assembly 120 in the three-phase power supply 200.

In any of the above embodiments, the detection circuit 100 further comprises a first detection element V ₁ And a second detecting member V ₂ 。

First detecting member V ₁ The first relay component 120 is arranged at a first end of the first relay component 120 and used for acquiring a voltage value of the first end of the first relay component 120; second detecting member V ₂ And is disposed at the second end of the first relay assembly 120, and is configured to collect a voltage value at the second end of the first relay assembly 120.

In this embodiment, the first detecting member V ₁ Is connected to a first end of a first relay assembly 120, a first sensing member V ₁ The voltage value of the first terminal of the first relay assembly 120 can be detected. Second detecting member V ₂ Is connected to a second terminal of the first relay assembly 120, and a second detecting member V ₂ The voltage value of the second terminal of the first relay assembly 120 can be detected.

First detecting member V ₁ And a second detecting member V ₂ Are all connected with a control device 130, and are arranged on a first detection piece V ₁ And a second detecting member V ₂ After the voltage values of the first terminal and the second terminal of the first relay assembly 120 are collected, the collected voltage values of the first terminal and the second terminal of the first relay assembly 120 are transmitted to the control device 130. The control device 130 can perform a difference calculation according to the voltage values of the first terminal and the second terminal of the first relay assembly 120 to obtain a first voltage difference value or a second voltage difference value.

Exemplarily, the first detecting member V ₁ And a second detecting member V ₂ And the control device 130 can be integrally provided.

In the embodiment, the first detection component V is respectively arranged at the first end and the second end of the first detection component ₁ And a second detecting member V ₂ It is possible to accurately detect the voltage values of the first terminal and the second terminal of the first relay assembly 120, thereby ensuring the calculated first voltage difference value and the calculated second voltage difference valueAccuracy of the value.

In an embodiment according to the present application, as shown in fig. 3, a detection method is provided for the detection circuit in the first aspect, and the detection method includes:

step 302, when the first relay assembly is in an off state, controlling the switch member to be switched from the off state to an on state;

step 304, acquiring a first voltage difference value when the switching element is in an off state and a second voltage difference value when the switching element is in an on state, wherein the first voltage difference value and the second voltage difference value are both voltage difference values between a first end and a second end of the first relay assembly;

step 306, determining a fault state of the first relay assembly according to the first voltage difference value and the second voltage difference value.

In this embodiment, during the initial detection phase, the control switch and the first relay assembly are both in the off state, and a first voltage difference across the first relay assembly is detected. Whether the first relay has a fault or not can be preliminarily judged based on the first voltage difference value. Under the condition that the first voltage difference value is small, it is determined that the two ends of the first relay assembly are possibly in a conducting state, and due to the design of a grounding system of the energy storage converter, the situation that the voltage values at the two ends of the first relay assembly are close to 0 possibly exists at the moment, so that the control switch piece is switched to the conducting state, and the second voltage values at the two ends of the first relay assembly are detected. After the switch is switched on, the resistor assembly is connected between the output end of the direct current bus and the grounding system, so that the voltage value of one end, close to the neutral line of the direct current bus, of the first relay assembly is changed, and at the moment, if the second voltage difference value of the two ends of the first relay assembly is smaller, it can be determined that the first relay assembly has a fault.

It should be noted that, because the first relay assembly includes at least two relays, and the first relay assembly is in the off state, which means that all relays are in the off state, it can be determined that at least one relay with an adhesion fault exists in the first relay assembly.

This embodiment sets up resistance component and switch spare through establishing ties between the output of the direct current bus at energy storage converter and earthing terminal, before control switch spare switches on, detects the first voltage difference at first relay subassembly both ends to and control switch spare arrives the back, detects the second voltage difference at first relay subassembly both ends, can accurately confirm whether there is the adhesion trouble first relay subassembly according to first voltage difference and second voltage difference. Through the on-off state of change over switch spare, can control whether resistance assembly inserts between direct current bus's output and earthing terminal to adjust the voltage value that first relay subassembly is close to direct current bus one end, avoided having the false retrieval of adhesion trouble to first relay subassembly.

The detection circuit in the embodiment only comprises the resistor assembly and the switch piece, and is matched with the control logic to realize accurate detection on whether the first relay assembly has the adhesion fault.

In the above embodiment, the first relay assembly includes the first relay and the second relay;

In this embodiment, the first relay assembly includes two relays, a first relay and a second relay respectively. The first relay is connected in series with the second relay. The first end of the first relay is used as the first end of the first relay assembly and is connected with a neutral line of a direct current neutral line. And the second end of the second relay is used as the second end of the first relay component and is connected with a zero line of the three-phase power supply. The second end of the first relay is connected with the first end of the second relay.

In this embodiment, the first relay and the second relay which are connected in series are arranged in the first relay assembly, so that the energy storage converter can be ensured to be in an electrical isolation state between the direct current bus and the three-phase power supply in a grid-connected state, and higher isolation stability is achieved compared with a scheme that only a single relay is arranged between the direct current bus and the three-phase power supply.

In any of the above embodiments, determining the fault condition of the first relay assembly based on the first voltage difference value and the second voltage difference value comprises:

Illustratively, the preset threshold value ranges from 0V to 30V.

In this embodiment, the first voltage difference is a voltage difference between two ends of the first relay assembly detected when the switching element and the first relay assembly are both in the off state. The second voltage difference value is a voltage difference value between two ends of the first relay assembly detected when the switch is in a conducting state and the first relay assembly is in a disconnecting state.

Due to the design of the grounding system (PE) in the energy storage converter system, the possibility of misjudgment is possibly existed only according to the first voltage difference value or the second voltage difference value to detect whether the first relay assembly has a fault, and the possibility of misjudgment can be effectively avoided by switching the on-off state of the switch element to adjust whether the resistance assembly is connected between the negative electrode of the direct current bus and the grounding system.

This embodiment is through the disconnection of a relay in the first relay subassembly of control, and another relay keeps switching on, according to first voltage difference and second voltage difference, can be in the relay of off-state and whether be in the fault condition and carry out accurate detection, has realized carrying out the effect of accurate location to the trouble of first relay subassembly.

In any of the above embodiments, a second relay assembly is provided between the three-phase input terminal of the energy storage converter and the three-phase power supply;

In this embodiment, the second relay assembly is used for controlling the on-off state between the three-phase input end of the energy storage converter and the three-phase power supply.

In any of the above embodiments, obtaining a first voltage difference value when the switching element is in the off state and a second voltage difference value when the switching element is in the on state includes:

when the switch piece is in an off state, acquiring a first voltage value of a first end of the first relay assembly and a second voltage value of a second end of the first relay assembly; determining a first voltage difference value according to the first voltage value and the second voltage value; when the switch element is in a conducting state, acquiring a first end and a third voltage value of the first relay assembly and a fourth voltage value of a second end of the first relay assembly; and determining a second voltage difference value according to the third voltage value and the fourth voltage value.

In this embodiment, the detection circuit further comprises a first detection member and a second detection member.

In this embodiment, the sampling end of the first detection element is connected to the first end of the first relay assembly, and the first detection element is capable of detecting the voltage value of the first end of the first relay assembly. The sampling end of the second detection piece is connected with the second end of the first relay assembly, and the second detection piece can detect the voltage value of the second end of the first relay assembly.

This embodiment sets up first detection piece and second detection piece respectively through the first end at first detection subassembly and second end, can accurately detect the voltage value of the first end of first relay subassembly and second end to guarantee the accuracy of the first voltage difference value and the second voltage difference value that calculate and obtain.

Specifically, as shown in fig. 4, in any of the above embodiments, the detection method includes:

step 402, simultaneously disconnecting the switch piece, the first relay and the second relay;

step 404, controlling the first relay and the switch to be disconnected, keeping the second relay closed, and recording that the voltage of the V1 is V10 and the voltage of the V2 is V20;

wherein, V1 is a voltage value of the first end of the first relay assembly, that is, a voltage value of the first end of the first relay, and V2 is a voltage value of the first end of the first relay assembly, that is, a voltage value of the second end of the second relay.

Step 406, judging whether the transmission is 'V10-V20' and < the preset threshold value, if so, executing step 412, otherwise, executing step 408;

wherein, | V10-V20 | is a first voltage difference value of which the first relay is in an off state.

Step 408, controlling the second relay and the switch to be disconnected, keeping the first relay closed, and recording that the voltage of the V1 is V12 and the voltage of the V2 is V22;

step 410, judging whether the agent V12-V22 < the preset threshold value, if so, executing step 412, otherwise, ending;

wherein | V12-V22 | is a first voltage difference value at which the second relay is in an open state.

Step 412, controlling the switch to be closed, and recording the voltage of the V1 as V11 and the voltage of the V2 as V21;

step 414, determining whether the agent V11-V21 < the preset threshold value, if yes, executing step 416, if no, executing step 408;

wherein | V12-V22 | is a second voltage difference value when the first relay or the second relay is in an off state.

And step 416, outputting adhesion fault prompt information of the first relay assembly.

In this embodiment, the control switch, the first relay, and the second relay are all in the off state at the start detection stage.

Whether adhesion fault exists in the first relay is detected, the first relay and the switch piece are controlled to be in an off state, the second relay is in a closed state, and a first voltage difference value is obtained at the moment. And under the condition that the first voltage difference value is detected to be larger than or equal to the preset threshold value, judging that the first relay has no fault. And under the condition that the first voltage difference value is smaller than the preset threshold value, controlling the switch part to be closed, and acquiring a second voltage difference value. And under the condition that the second voltage difference value is detected to be larger than or equal to the preset threshold value, judging that the first relay has no fault. And determining that the first relay has adhesion fault under the condition that the second voltage difference value is smaller than the preset threshold value.

Under the condition that the first relay is detected to be free of faults, whether adhesion faults exist in the second relay or not is detected, the second relay and the switch piece are controlled to be in an off state, the first relay is in a closed state, and the first voltage difference value is obtained at the moment. And under the condition that the first voltage difference value is detected to be larger than or equal to the preset threshold value, judging that the second relay has no fault. And under the condition that the first voltage difference value is smaller than the preset threshold value, controlling the switch part to be closed, and acquiring a second voltage difference value. And under the condition that the second voltage difference value is detected to be larger than or equal to the preset threshold value, judging that the second relay has no fault. And determining that the second relay has adhesion fault under the condition that the detected second voltage difference value is smaller than the preset threshold value.

And under the condition that the adhesion fault exists in any one of the first relay and the second relay, outputting adhesion fault prompt information of the first relay assembly.

In an embodiment according to the present application, as shown in fig. 5, a detection apparatus is proposed, which is used in the detection circuit in the first aspect, and the detection apparatus 500 includes:

the control module 502 is configured to control the switching element to switch from the off state to the on state when the first relay assembly is in the off state;

an obtaining module 504, configured to obtain a first voltage difference value when the switching element is in an off state and a second voltage difference value when the switching element is in an on state, where the first voltage difference value and the second voltage difference value are both voltage difference values between a first end and a second end of the first relay assembly;

a determination module 506 is configured to determine a fault condition of the first relay assembly based on the first voltage difference value and the second voltage difference value.

In an embodiment according to the present application, as shown in fig. 6, there is provided a detection assembly 600 comprising: a processor 602 and a memory 604, the memory 604 having programs or instructions stored therein; the processor 602 executes the program or the instructions stored in the memory 604 to implement the steps of the detection method in any of the embodiments, so that all the advantageous technical effects of the detection method in any of the embodiments are achieved, and redundant description is not repeated herein.

In an embodiment according to the present application, a readable storage medium is proposed, on which a program or instructions are stored, which when executed by a processor implement the steps of the detection method as in any of the above embodiments. Therefore, all the beneficial technical effects of the detection method in any of the above embodiments are achieved, and no redundant description is given here.

In an embodiment according to the present application, as shown in fig. 7, there is provided an energy storage system 700, including: the detection apparatus 500, and/or the detection component 600, and/or the readable storage medium 702 in the foregoing embodiments have all the beneficial technical effects of the detection apparatus 500, the detection component 600, and/or the readable storage medium 702 defined in the foregoing embodiments, which are not described in detail herein again.

It is to be understood that, in the claims, the specification and the drawings of the specification of the present invention, the term "plurality" means two or more, unless explicitly defined otherwise, the terms "upper", "lower" and the like indicate orientations or positional relationships based on those shown in the drawings, and are used only for the purpose of describing the present invention more conveniently and simplifying the description, and are not used to indicate or imply that the device or element referred to must have the specific orientation described, be constructed in a specific orientation, and be operated, and thus the description should not be construed as limiting the present invention; the terms "connect," "mount," "secure," and the like are to be construed broadly, and for example, "connect" may refer to a fixed connection between multiple objects, a removable connection between multiple objects, or an integral connection; the multiple objects may be directly connected to each other or indirectly connected to each other through an intermediate. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art from the above data specifically.

In the claims, specification, and drawings that follow the present disclosure, the description of the terms "one embodiment," "some embodiments," "specific embodiments," and so forth, means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In the claims, specification and drawings of the specification, schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A detection circuit for detecting a fault condition of a first relay assembly between a neutral line of a dc bus of an energy storage converter and a neutral line of a three phase power supply, the detection circuit comprising:

a resistance component;

the switch piece and the resistance component are connected in series between the output end of the direct current bus and a grounding end;

a control device connected to the first relay assembly and the switch member, respectively, the control device being configured to:

when the first relay assembly is in an off state, controlling the switch piece to be switched from the off state to an on state;

acquiring a first voltage difference value of the switching element in the off state and a second voltage difference value of the switching element in the on state, wherein the first voltage difference value and the second voltage difference value are both voltage difference values at two ends of the first relay assembly;

determining a fault state of the first relay assembly according to the first voltage difference value and the second voltage difference value.

2. The detection circuit of claim 1, wherein the first relay assembly comprises: the first relay and the second relay are connected in series, one end of the first relay is connected with a neutral line of the direct current bus, and one end of the second relay is connected with a zero line of the three-phase power supply;

the first relay assembly being in an open state comprises:

the first relay is in an off state; and/or

The second relay is in an open state.

3. The detection circuit according to claim 2, wherein the control means determines the fault state of the first relay assembly from the first voltage difference value and the second voltage difference value, in particular for:

and determining that a target relay in the first relay assembly is in a fault state based on the first voltage difference value and the second voltage difference value being smaller than a preset threshold value, wherein the target relay is a relay in a disconnection state in the first relay and the second relay.

4. The detection circuit according to any one of claims 1 to 3, wherein a second relay assembly is arranged between the three-phase input of the energy storage converter and the three-phase power supply;

the control device is connected with the second relay assembly;

before the first relay assembly is in the off state and the switching piece is controlled to be switched from the off state to the on state, the control device is further configured to:

and controlling the second relay assembly to be in an open state.

5. The detection circuit of claim 4, further comprising:

and the capacitive component is arranged between the three-phase input end of the energy storage converter and the first relay component.

6. The detection circuit according to any one of claims 1 to 3, further comprising:

the first detection piece is arranged at the first end of the first relay assembly and used for collecting the voltage value of the first end of the first relay assembly;

and the second detection piece is arranged at the second end of the first relay assembly and used for acquiring the voltage value of the second end of the first relay assembly.

7. A detection method for use in the detection circuit of any one of claims 1 to 6, comprising:

obtaining a first voltage difference value when the switching element is in the off state and a second voltage difference value when the switching element is in the on state, wherein the first voltage difference value and the second voltage difference value are both voltage difference values between a first end and a second end of the first relay assembly;

8. The method of testing as defined in claim 7, wherein the first relay assembly includes a first relay and a second relay;

the first relay assembly being in an open state comprises: the first relay is in an off state; and/or the second relay is in an open state.

9. The method of testing as defined in claim 8, wherein said determining a fault condition of said first relay assembly as a function of said first voltage difference value and said second voltage difference value comprises:

10. The method according to any one of claims 7 to 9, wherein a second relay assembly is provided between the three-phase input of the energy storage converter and the three-phase power supply;

before the first relay assembly is in the off-state and the switching piece is controlled to be switched from the off-state to the on-state, the method further comprises the following steps:

and controlling the second relay assembly to be in an open state.

11. The method according to any one of claims 7 to 9, wherein the obtaining a first voltage difference value when the switching element is in the off state and a second voltage difference value when the switching element is in the on state comprises:

when the switch piece is in an off state, acquiring a first voltage value of a first end of the first relay assembly and a second voltage value of a second end of the first relay assembly;

determining the first voltage difference value according to the first voltage value and the second voltage value;

when the switch piece is in a conducting state, acquiring a first end and a third voltage value of the first relay assembly and a fourth voltage value of a second end of the first relay assembly;

and determining the second voltage difference value according to the third voltage value and the fourth voltage value.

12. A detection apparatus for use in the detection circuit of any one of claims 1 to 6, comprising:

the control module is used for controlling the switching piece to be switched from the off state to the on state when the first relay assembly is in the off state;

the acquisition module is used for acquiring a first voltage difference value when the switching element is in the off state and a second voltage difference value when the switching element is in the on state, wherein the first voltage difference value and the second voltage difference value are both voltage difference values between a first end and a second end of the first relay assembly;

13. A detection assembly, comprising:

a memory having a program or instructions stored thereon;

a processor for implementing the steps of the detection method of any one of claims 7 to 11 when executing the program or instructions.

14. A readable storage medium on which a program or instructions are stored, characterized in that said program or instructions, when executed by a processor, implement the steps of the detection method according to any one of claims 7 to 11.

15. An energy storage system, comprising:

the detection device of claim 12; and/or

The detection assembly of claim 13; and/or

The readable storage medium of claim 14.