Grid-connected and off-grid switching control circuit and grid-connected and off-grid switching cabinet

Abstract

The invention discloses a grid-connected and off-grid switching control circuit and a grid-connected and off-grid switching cabinet, relates to the technical field of grid-connected and off-grid switching, and is used for providing a safe and reliable manual grid-connected and off-grid switching control scheme. The grid-connected and off-grid switching control circuit realizes manual operation of a button based on a user, and can control opening and closing of any controlled frame circuit breaker in the grid-connected and off-grid switching cabinet. And the detection unit is used for detecting whether the local alternating current bus of the grid-connected and off-grid switching cabinet is electrified so as to judge whether the frame circuit breaker on the other side is opened before closing. And if the frame circuit breaker on the other side is not switched off, the controlled frame circuit breaker is automatically locked and cannot be switched on, and the controlled frame circuit breaker cannot be really switched on even if the user performs misoperation. Therefore, the safety risk that the power grid is directly connected with the energy storage system due to the misoperation problem which cannot be completely eradicated by manual control is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of grid-connected and off-grid switching, and particularly to a grid-connected and off-grid switching control circuit and a grid-connected and off-grid switching cabinet. Background Art

[0002] In a power system, a grid-connected and off-grid switching cabinet is used to ensure uninterrupted operation of a load. Among them, powering the load through the main power grid is called grid connection, and powering the load through a backup power source such as an energy storage system is called off-grid. The grid-connected and off-grid switching cabinet realizes the switching control between grid connection and off-grid by setting frame circuit breakers with mutually exclusive switch states between the power grid and a power conversion system (PCS, an important part of the energy storage system).

[0003] Since the circuit voltage level for grid-connected and off-grid switching is relatively high, higher safety requirements are imposed on the opening and closing control of each frame circuit breaker in the grid-connected and off-grid switching cabinet. Currently, the opening and closing control of the frame circuit breaker is generally realized in a timely and reliable manner through devices such as a parallel operation control board. However, with the continuous expansion of the application scenarios of the grid-connected and off-grid switching cabinet and the continuous change of actual requirements, in some special cases, there is also a need to manually control the opening and closing of the frame circuit breaker.

[0004] However, since on-site personnel cannot fully master all aspects of the actual site, problems of misoperation may occur. Among the possible misoperations, the most serious consequence is caused by the simultaneous closing of the frame circuit breakers on the grid side and the PCS side. The simultaneous closing of the frame circuit breakers on the grid side and the PCS side will directly connect the power grid and the energy storage system, thereby bringing great safety risks.

[0005] Therefore, those skilled in the art urgently need a grid-connected and off-grid switching control circuit to avoid serious safety risks such as the direct connection of the power grid and the energy storage system when manually realizing the opening and closing control of the frame circuit breaker in the grid-connected and off-grid switching cabinet. Summary of the Invention

[0006] The purpose of the present application is to provide a grid-connected and off-grid switching control circuit and a grid-connected and off-grid switching cabinet to provide a safe and reliable manual grid-connected and off-grid switching control solution.

[0007] To solve the above technical problems, the present application provides a grid-connected and off-grid switching control circuit, including: a controlled circuit, a master command switch module, and a detection and locking module;

[0008] Among them, the controlled circuit is a series circuit of the coil and auxiliary contact of a controlled frame circuit breaker and a power source; the auxiliary contact is a normally open contact;

[0009] The master command switch module includes: a button, a control circuit, and a switch unit;

[0010] The switch unit is connected in series in the controlled loop; the control loop is configured to switch the switch state of the switch unit when the button is pressed.

[0011] The detection and locking module includes: a locking unit and a detection unit.

[0012] The detection unit is arranged on the AC busbar local to the grid-connected and off-grid switching cabinet and is configured to detect whether the AC busbar is powered.

[0013] The locking unit is connected in parallel across the auxiliary contact and is configured to: switch its own switch state to open when the detection unit detects that the AC busbar is powered; switch its own switch state to closed when the detection unit detects that the AC busbar is not powered.

[0014] In a possible embodiment, the detection and locking module is a relay.

[0015] Wherein, the coil of the relay is the detection unit in the detection and locking module, the contact of the relay is the locking unit, and the contact of the relay is a normally closed contact.

[0016] In a possible embodiment, the button includes: a closing button and a tripping button.

[0017] Then the switch unit includes: a closing switch and a tripping switch.

[0018] The closing switch is connected in series in the parallel branch where the auxiliary contact is located, and the closing switch is a normally open switch.

[0019] The tripping switch is connected in series in the main path of the controlled loop, and the tripping switch is a normally closed switch.

[0020] The control loop is configured to: close the closing switch when the closing button is pressed; open the tripping switch when the tripping button is pressed.

[0021] In a possible embodiment, the button is one.

[0022] Then the control loop is configured to: switch and maintain the switch state of the switch unit when the button is pressed.

[0023] In a possible embodiment, the controlled frame circuit breaker is a frame circuit breaker on the grid side.

[0024] In a possible embodiment, the power source in the controlled loop is the grid.

[0025] In a possible embodiment, the controlled frame circuit breaker is a frame circuit breaker on the energy storage converter side.

[0026] In a possible embodiment, the power supply in the controlled loop is a battery energy storage converter.

[0027] To solve the above technical problems, the present application also provides a grid-connected and off-grid switching cabinet, including the grid-connected and off-grid switching control circuit as described above.

[0028] In a possible embodiment, the number of the grid-connected and off-grid switching control circuits is two, and the two grid-connected and off-grid switching control circuits respectively use the frame circuit breakers on the grid side and the battery energy storage converter side as the controlled frame circuit breakers.

[0029] The grid-connected and off-grid switching control circuit provided by the present application detects whether there is electricity on the local AC bus of the grid-connected and off-grid switching cabinet to determine whether the closing condition of the controlled frame circuit breaker can be met before switching the grid-connected and off-grid modes. Specifically, whether it is switching from grid-connected to off-grid or from off-grid to grid-connected, before the frame circuit breaker on the grid side or the PCS side is closed, it is necessary to ensure that the frame circuit breaker on the other side is opened first. For this purpose, this circuit detects whether there is electricity on the local AC bus of the grid-connected and off-grid switching cabinet through the detection unit. If there is electricity, it means that the frame circuit breaker on the other side is not opened. At this time, the locking unit will be disconnected, resulting in the disconnection of the controlled loop. That is, even if the user closes the switch unit through the button in the main command switch module, the coil of the controlled frame circuit breaker cannot be powered on. That is, even if the user makes a misoperation (accidentally presses the button), the controlled frame circuit breaker will not be accidentally closed, thus ensuring the safety of the grid-connected and off-grid system. At the same time, if the frame circuit breaker on the other side has been closed, there is no electricity on the local AC bus of the grid-connected and off-grid switching cabinet. At this time, the detection unit controls the locking unit to close, and the user can control whether the controlled loop is conducted through the button, that is, control whether the controlled frame circuit breaker is closed, meeting the requirement of manually controlling the grid-connected and off-grid switching.

[0030] It can be seen that the grid-connected and off-grid switching control circuit provided by the present application provides a manual control scheme for the grid-connected and off-grid switching control scenario. Based on the user's manual operation of the button, the opening and closing of any frame circuit breaker in the grid-connected and off-grid switching cabinet can be controlled. And when the frame circuit breaker on the other side is not opened, the controlled frame circuit breaker is automatically locked and cannot be closed. Even if the user makes a misoperation, the controlled frame circuit breaker will not be actually closed. Thus, it avoids the safety risk of the direct connection between the power grid and the energy storage system caused by the misoperation problem that cannot be eliminated by manual control.

[0031] The grid-connected and off-grid switching cabinet provided by the present application corresponds to the above circuit, and the effect is the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To more clearly illustrate the embodiments of the present application, the following will briefly introduce the accompanying drawings required for the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0033] Figure 1 It is a structural schematic diagram of a grid-connected and off-grid switching cabinet;

[0034] Figure 2 It is a structural schematic diagram of a grid-connected and off-grid switching control circuit provided by the present invention;

[0035] Figure 3 It is another structural schematic diagram of a grid-connected and off-grid switching control circuit provided by the present invention. Specific embodiments

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present application.

[0037] The core of the present application is to provide a grid-connected and off-grid switching control circuit and a grid-connected and off-grid switching cabinet.

[0038] To enable those in the technical field of the present application to better understand the solution of the present application, the following will further elaborate on the present application in conjunction with the accompanying drawings and specific embodiments.

[0039] As Figure 1 shown, when realizing the mutual switching between the system grid connection and off-grid through the grid-connected and off-grid switching cabinet, it is achieved by the opening and closing of two frame circuit breakers (KM1 and QF2) set on the grid side and the energy storage converter (PCS) side in the control cabinet. Currently, for the control of the frame circuit breakers in the grid-connected and off-grid switching cabinet, it is generally achieved through controller components such as a parallel operation control board. This scheme of realizing indirect electric control by means of controller components can add an interlock mechanism to the control logic of the parallel operation control board, so that the opening and closing control signals output to the two frame circuit breakers on the grid side and the PCS side are always opposite, thereby ensuring that the two frame circuit breakers will not close simultaneously and avoiding the direct connection between the grid and the energy storage system.

[0040] However, in actual applications, in some special application scenarios, there is a need to manually control the frame circuit breakers in the grid-connected and off-grid switching cabinet. At this time, it is not desired to introduce controller components such as a parallel operation control board, but to realize manual grid-connected and off-grid switching control by on-site personnel through buttons and switch circuits, etc.

[0041] Due to the uncertainty of human factors, manual control cannot ensure that on-site personnel will definitely control the closing on the other side only after the frame circuit breaker on the grid side or the PCS side is tripped. It may cause both frame circuit breakers on both sides to be closed due to misoperation. At this time, the grid and the energy storage system will be directly connected, bringing serious safety hazards.

[0042] To solve the above problems, the present application provides a grid-connected and off-grid switching control circuit, as Figure 2 shown, including: a controlled circuit, a master switch module 20, and a detection and locking module 30;

[0043] Among them, the controlled circuit is a series circuit of the coil 11 and the auxiliary contact 12 of the controlled frame circuit breaker and the power supply; the auxiliary contact 12 is a normally open contact;

[0044] The master switch module includes: a button 21, a control circuit 22, and a switch unit 23;

[0045] The switch unit 23 is connected in series in the controlled circuit; the control circuit 22 is used to switch the switch state of the switch unit 23 when the button 21 is pressed;

[0046] The detection and locking module 30 includes: a locking unit 31 and a detection unit 32;

[0047] The detection unit 32 is arranged on the AC busbar locally in the grid-connected and off-grid switching cabinet and is used to detect whether the AC busbar is powered;

[0048] The locking unit 31 is connected in parallel across the two ends of the auxiliary contact 12 and is used to: switch its own switch state to off when the detection unit 32 detects that the AC busbar is powered; switch its own switch state to on when the detection unit 32 detects that the AC busbar is not powered.

[0049] It can be easily seen from the above circuit structure that the master switch module 20 is a control circuit for on-site personnel to manually control the opening and closing states of the frame circuit breaker. On-site personnel can control the switch state of the switch unit 23 connected in series in the controlled circuit by pressing the button 21, that is, control whether the coil 11 of the controlled frame circuit breaker is powered. When the coil 11 of the controlled frame circuit breaker is powered, the corresponding contact in the main circuit of the grid-connected and off-grid switching cabinet will close, connecting the controlled side (i.e., the grid side or the PCS side where the controlled frame circuit breaker is located) to the load.

[0050] The detection and locking module 30 is used to ensure the safety in manual switching control. Specifically, as can be seen from the above description of the grid connection / disconnection switching control process, whenever a grid connection / disconnection switching is performed, the closing control of the grid-side or PCS-side frame circuit breaker always needs to be carried out after the other frame circuit breaker has been opened. Since it is not easy to directly detect the opening and closing states of the other frame circuit breaker. This circuit detects whether there is power on the local AC bus of the grid connection / disconnection switching cabinet through the detection unit 32 to indirectly determine the opening and closing states of the other frame circuit breaker; if there is no power on the AC bus, it means that both frame circuit breakers are in the open state, that is, the other frame circuit breaker has been opened, and the local frame circuit breaker can be closed; if there is power on the AC bus, it means that the other frame circuit breaker is still in the open state, and at this time the local frame circuit breaker is not allowed to be closed. Otherwise, it will cause the direct connection between the power grid and the energy storage system, which may bring potential safety hazards.

[0051] When the detection unit 32 detects that there is power on the AC bus, the locking unit 31 in the detection and locking module 30 will be in the open state. Since the locking unit 31 is also connected in series in the controlled circuit, regardless of the switching state of the switching unit 23, the controlled circuit is always open, and the coil 11 of the controlled frame circuit breaker cannot be energized, and the controlled frame circuit breaker will not close. Similarly, if the detection unit 32 does not detect power on the AC bus, the locking unit 31 will close. At this time, the locking unit 31 is equivalent to a conducting path in the controlled circuit, and whether the coil 11 of the controlled frame circuit breaker is energized is controlled by the master switch module 20, meeting the requirement of manually controlling the frame circuit breaker in the grid connection / disconnection switching cabinet.

[0052] In addition, it should be noted that the auxiliary contact 12 in the controlled circuit is designed in the controlled circuit according to the working characteristics of the above detection and locking module 30, and is used to realize the self-locking of the controlled circuit. That is, when the controlled frame circuit breaker closes after its coil 11 is energized, the auxiliary contact 12 will also close. At this time, the detection and locking module 30 will no longer disconnect the controlled circuit because there is power on the AC bus (because there must be power on the AC bus after the controlled frame circuit breaker closes, and at this time if the locking unit 31 is disconnected, the controlled frame circuit breaker cannot close normally).

[0053] However, since the auxiliary contact 12 is connected in parallel across the locking unit 31, the self-locking function it realizes is only for the locking unit 31 and does not affect the on / off control of the controlled circuit by the master switch module 20. Since the switching unit 23 in the master switch module 20 is connected in series in the controlled circuit, when the switching unit 23 is disconnected, the coil 11 of the controlled frame circuit breaker is not energized, and the auxiliary contact 12 will also be disconnected, thus releasing the self-locking state.

[0054] It is easy to understand that the controlled frame circuit breaker can be the frame circuit breaker on the grid side or the frame circuit breaker on the PCS side, and this embodiment does not limit this. In practical applications, this circuit can be deployed on one side of the grid side or the PCS side based on control needs, or this circuit can be deployed on both sides to achieve safer manual opening and closing control of any controlled frame circuit breaker in the grid-connected and off-grid switching cabinet.

[0055] In summary, this application provides a grid-connected and off-grid switching control circuit, which provides a safe manual opening and closing control scheme for any frame circuit breaker in the grid-connected and off-grid switching cabinet. By detecting whether there is power on the local AC bus of the grid-connected and off-grid switching cabinet, it is possible to determine whether the frame circuit breaker on the other side is tripped. When the frame circuit breaker on the other side is not tripped, the detection and locking module 30 will lock the controlled circuit in the open state, and on-site personnel cannot control the controlled frame circuit breaker to close through the button 21. That is to say, this circuit realizes a foolproof design for the frame circuit breaker in the grid-connected and off-grid switching cabinet. Even if on-site personnel make a misoperation, the frame circuit breakers on the grid side and the PCS side will not be conducted simultaneously, thus avoiding the safety problems brought about by this, and providing a safer and more reliable manual grid-connected and off-grid switching control scheme.

[0056] On the other hand, as can be seen from the above embodiments, the detection and locking module 30 is the key to enabling this circuit to provide a safe and reliable manual grid-connected and off-grid switching control. The detection and locking module 30 needs to be able to detect whether there is power on the AC bus and decide whether to lock the controlled circuit according to the detection result. Since the above functions are common functions in circuit design and applications, the above embodiments do not limit the specific implementation manner of the detection and locking module 30.

[0057] For example, the detection unit 32 in the detection and locking module 30 needs to have the functions of collecting and comparing electrical signals, and the electrical signal can specifically be voltage or current. When the electrical signal is a voltage signal, the detection unit 32 can be implemented by a voltage acquisition circuit and a voltage comparator, or can be implemented by other devices with voltage acquisition and comparison functions (such as a single-chip microcomputer, a power management chip, etc.). Similarly, if the electrical signal is a current signal, the detection unit 32 needs to have the functions of current acquisition and current comparison, and can be implemented based on a current acquisition circuit and a current comparator, or other controller devices with current acquisition and comparison functions. Since the implementation forms of current and voltage are similar, only voltage will be used in the subsequent examples for illustration. The locking unit 31 can be a switch, and its switch state is controlled by the detection unit 32, and can be implemented by any electronic switch, and this embodiment does not limit this.

[0058] However, since the present circuit is targeted at a relatively special application scenario, that is, it is desired that the on-off of the frame circuit breaker in the off-grid switching cabinet be manually controlled by on-site personnel. That is, in this scenario, there may be a need to avoid introducing control devices as much as possible. Then, the above solution for implementing the detection and locking module 30 through control devices such as a single-chip microcomputer and a power management chip is contrary to this need.

[0059] To meet this need, this embodiment provides a possible implementation solution for the detection and locking module 30, as Figure 3 shown:

[0060] The detection and locking module 30 is a relay K0.

[0061] Among them, the coil 11 of the relay K0 is the detection unit 32 in the detection and locking module 30, the contact of the relay K0 is the locking unit 31, and the contact of the relay K0 is a normally closed contact.

[0062] Based on the principle of the relay, when the coil of the relay K0 is energized, the contact of the relay K0 will switch from the default state to another state. The coil therein plays the role of detecting whether there is electricity at the detection setting, and the contact plays the role of switching the conduction state in response to the detection result. Especially when the contact of the relay K0 is a normally closed contact, it well meets the requirements for the detection and locking module 30 in the above embodiment.

[0063] This embodiment provides a solution for implementing the above detection and locking module 30 through a relay. The relay is a conventional device in the power system, which is easy to implement and reliable. Moreover, the relay does not belong to the control device, perfectly meeting the requirement of not introducing too many control devices in the manual control and off-grid switching scenario.

[0064] On the other hand, for the above master switch module 20, it is a hardware module that receives the manual input control command from on-site personnel through the button 21 and actually controls the on-off of the controlled circuit through the switch unit 23. Among them, there are two control actions implemented by the master switch module 20. One is to control the closing of the frame circuit breaker, and the other is to control the opening of the frame circuit breaker. In actual implementation, the above two control actions can be triggered by different instructions, or can be alternately triggered by the same instruction. This embodiment does not limit this. However, based on the above two possible implementation solutions, this embodiment also correspondingly provides an implementation solution for the master switch module 20.

[0065] Based on the opening and closing actions being triggered by different instructions, this embodiment provides a possible implementation solution for the master switch module 20, as Figure 3 shown, the button 21 includes: a closing button SB1 and an opening button SB2.

[0066] Then the switch unit 23 includes: a closing switch K1 and a tripping switch K2.

[0067] The closing switch is connected in series in the parallel branch where the auxiliary contact 12 is located, and the closing switch is a normally open switch.

[0068] The tripping switch is connected in series in the main path of the controlled circuit, and the tripping switch is a normally closed switch.

[0069] The control circuit 22 is used to: close the closing switch when the closing button is pressed; open the tripping switch when the tripping button is pressed.

[0070] Based on the implementation scheme of the double-button switch provided in this embodiment, the master switch module 20 can be implemented by two contactors 20A and 20B. Among them, the contactor 20A corresponds to the closing button and the closing switch. When the closing button is pressed, it is equivalent to the master switch module 20 receiving a closing instruction, and the closing switch closes. At this time, if there is no power on the AC bus, the locking module connected in series with it in the same parallel branch is also in the closed state, and this parallel branch is conducting. And because the master switch module 20 has not received a tripping instruction at this time, the tripping switch is in the default state, that is, the closed state, and the controlled circuit is conducting, and the coil 11 of the controlled frame circuit breaker is energized and closed. And after that, even if the closing button is released, the auxiliary contact 12 of the controlled frame circuit breaker will also close because the coil 11 is energized, keeping the coil 11 of the controlled frame circuit breaker energized.

[0071] The contactor 20B corresponds to the tripping button and the tripping switch. The function of the tripping button and the tripping switch is to trip the controlled frame circuit breaker in the closed state, that is, to disconnect the conducting and self-locking controlled circuit and restore it to the initial state. At this time, the on-site personnel can press the tripping button to switch the tripping switch connected in series in the main path of the controlled circuit from the default closed state to the open state, then the controlled circuit is disconnected, and the controlled frame circuit breaker trips due to the power failure of the coil 11, and the auxiliary contact 12 also disconnects due to the power failure of the coil 11, and the controlled circuit releases the self-locking state.

[0072] The implementation scheme of the master switch module 20 provided in this embodiment is provided with two different buttons for on-site personnel to input specific closing and tripping instructions. Compared with the implementation scheme with only one button to switch the current closing and tripping states by pressing, the input method of the control instruction is more intuitive. It can effectively prevent on-site personnel from inputting incorrect control instructions to switch the closing and tripping states because they are not clear about the current closing and tripping states, thereby further improving the reliability and safety during manual control and off-grid switching.

[0073] On the other hand, this embodiment also provides an implementation scheme of the master switch module 20 based on the method that the closing and tripping actions are alternately triggered by the same instruction: the button 21 is one.

[0074] The control circuit 22 is configured to: when the button 21 is pressed, switch and maintain the switching state of the switch unit 23.

[0075] At this time, the master switch module 20 can be implemented by a self-locking switch. Each time the button 21 is pressed, the switching state of the self-locking switch is switched once. When the button 21 is not pressed, the self-locking switch always maintains the current switching state.

[0076] Compared with the previous embodiment, the master switch module implementation provided in this embodiment can reduce the number of switches to be set and the complexity of the control circuit, thereby facilitating cost savings, reducing the complexity of on-site wiring, and being easier to implement.

[0077] On the other hand, the controlled frame circuit breaker is not restricted in the above embodiment. For the on-grid / off-grid switching control scenario, the controlled frame circuit breaker can be any frame circuit breaker in the on-grid / off-grid switching cabinet. As Figure 1 shown, the key ones among them are the frame circuit breaker KM1 on the grid side and the frame circuit breaker QF2 on the PCS side.

[0078] Therefore, this embodiment provides two possible implementation schemes for the controlled frame circuit breaker:

[0079] As Figure 3 shown, the controlled frame circuit breaker is the frame circuit breaker on the grid side.

[0080] Or:

[0081] The controlled frame circuit breaker is the frame circuit breaker on the energy storage converter side.

[0082] It can be clearly seen from the above embodiments that the on-grid / off-grid switching control circuit provided in this application is used to provide a safe and reliable manual switching control scheme for the frame circuit breaker. The effect of "safety" is mainly reflected in that before closing the controlled frame circuit breaker, it is first judged whether the frame circuit breaker on the other side has been opened. If it has not been opened, even if the on-site personnel issue a closing command, it will not actually close, avoiding safety problems caused by the direct connection of the power grid and the energy storage system.

[0083] During the off-grid to grid-connected mode switching process, the frame circuit breaker on the PCS side needs to trip first, and then the frame circuit breaker on the grid side needs to close. Among them, the frame circuit breaker on the grid side has the above-mentioned need to achieve safe manual switching control. Taking the frame circuit breaker on the grid side as the controlled frame circuit breaker can effectively ensure the switching control safety during the off-grid to grid-connected mode switching process. Similarly, taking the frame circuit breaker on the PCS side as the controlled frame circuit breaker can effectively ensure the switching control safety during the grid-connected to off-grid mode switching process. In another possible implementation, two grid-connected and off-grid switching control circuits can also use the frame circuit breakers on the grid side and the PCS side as the controlled frame circuit breakers respectively, so as to ensure the manual switching control safety of the grid-connected and off-grid switching cabinet.

[0084] Furthermore, this embodiment also provides a further implementation for the selection of the power supply in the controlled loop when using the frame circuit breakers on different sides as the controlled frame circuit breakers:

[0085] When the controlled frame circuit breaker is the frame circuit breaker on the grid side, the power supply in the controlled loop is the grid (such as Figure 1 and Figure 3 the L1 in).

[0086] When the controlled frame circuit breaker is the frame circuit breaker on the energy storage converter side, the power supply in the controlled loop is the energy storage converter.

[0087] It is easy to understand that, as the existing power supplies in the grid-connected and off-grid system, the grid and the energy storage converter are reused to supply power to the controlled loop, which can reduce the introduction of additional power supplies. However, when selecting the grid or PCS as above based on the difference in the controlled frame circuit breaker, additional effects can also be brought:

[0088] Taking the controlled frame circuit breaker as the frame circuit breaker on the grid side and the power supply in the controlled loop as the grid as an example, as shown in Figure 3 . It has been described above that the switching from the grid-connected mode to the off-grid mode is usually caused by grid anomalies (mains anomalies). At this time, when the power supply in the controlled loop is the grid, the grid anomaly will cause the power supply in the controlled loop to be abnormal. Then, regardless of the switch states of the switches on the controlled loop at this time, the coil 11 of the controlled frame circuit breaker will lose power, resulting in the automatic tripping of the frame circuit breaker on the grid side. Thus, it is ensured that before the frame circuit breaker on the PCS side closes, the frame circuit breaker on the grid side has tripped, avoiding the safety risk of both closing simultaneously. Similarly, when the controlled frame circuit breaker is the frame circuit breaker on the PCS side and the power supply in the controlled loop is the PCS.

[0089] It can be seen that based on the implementation solution provided in this embodiment, the grid-connected to off-grid switching control circuit can be deployed in the single-side frame circuit breaker in the power grid or PCS to achieve the two-way safe manual switching control of grid-connected to off-grid switching and off-grid to grid-connected switching. On the one hand, it can ensure that the frame circuit breaker on the other side has been tripped before the controlled frame circuit breaker is closed; on the other hand, it can also ensure that the controlled frame circuit breaker has been tripped before the frame circuit breaker on the other side needs to be closed; thus, it can avoid the simultaneous conduction of the frame circuit breakers on both sides in both directions, that is, it can effectively avoid the direct connection between the power grid and the energy storage system at any time. There is no need to deploy the grid-connected and off-grid switching control circuit on both frame circuit breakers, which can also bring more reliable safety assurance.

[0090] In the above embodiment, a grid-connected and off-grid switching control circuit is described in detail. The present application also provides an embodiment corresponding to a grid-connected and off-grid switching cabinet.

[0091] This embodiment provides a grid-connected and off-grid switching cabinet, including the grid-connected and off-grid switching control circuit described in the above embodiment.

[0092] Since the embodiment of the switching cabinet part corresponds to the embodiment of the circuit part, please refer to the description of the embodiment of the circuit part for the embodiment of the switching cabinet part, which will not be elaborated here. However, this embodiment also provides a further implementation solution for the grid-connected and off-grid switching cabinet:

[0093] The number of grid-connected and off-grid switching control circuits deployed in the grid-connected and off-grid switching cabinet is two. And the two grid-connected and off-grid switching control circuits respectively use the frame circuit breakers on the grid side and the energy storage converter side as the controlled frame circuit breakers.

[0094] In this embodiment, the above grid-connected and off-grid switching control circuits are deployed on both of the two key frame circuit breakers in the grid-connected and off-grid switching cabinet, so as to achieve the manual control of complete grid-connected and off-grid switching and ensure the safety of manual control well.

[0095] Further, when two grid-connected and off-grid switching control circuits are deployed in the grid-connected and off-grid switching cabinet as in the above embodiment, the two grid-connected and off-grid switching control circuits can share one or a group of buttons, but the switching states of their corresponding switch units are always opposite.

[0096] For example, when there are two buttons, namely a trip button and a close button, in the above circuit part embodiment, assuming these two buttons are button A and button B; if button A is the close button for the frame circuit breaker on the grid side, then button A is the trip button for the frame circuit breaker on the PCS side; similarly, at this time, button B is the trip button for the frame circuit breaker on the grid side and the close button for the frame circuit breaker on the PCS side.

[0097] When only one button is provided as described in the above embodiments of the circuit part, the default states of the switch units in the two circuits are opposite, which can also meet the control requirements and ensure safety.

[0098] Based on the shared button solution provided in this embodiment, the complexity of manual control can be further simplified, thereby further reducing the safety risks caused by misoperations of on-site personnel. It is also beneficial to reduce the implementation cost and simplify the wiring of the on-site control circuit.

[0099] The above has introduced in detail a grid-connected and off-grid switching control circuit and a grid-connected and off-grid switching cabinet provided by this application. The embodiments in the specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part. It should be noted that for those of ordinary skill in the art, without departing from the principle of this application, several improvements and modifications can be made to this application, and these improvements and modifications also fall within the protection scope of this application.

[0100] It should also be noted that in this specification, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising a..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the element.

Claims

1. A grid-connected and off-grid switching control circuit, characterized in that: include: Controlled circuit, master switch module and detection locking module; Wherein, the controlled circuit is a series circuit of the coil and auxiliary contact of the controlled frame circuit breaker and the power supply; the auxiliary contact is a normally open contact; The master switch module includes: a button, a control circuit and a switch unit; The switch unit is connected in series in the controlled loop; the control loop is used to switch the switch state of the switch unit when the button is pressed; The detection and locking module comprises: a locking unit and a detection unit; The detection unit is arranged on the local AC bus of the on-grid and off-grid switching cabinet, and is used to detect whether the AC bus has electricity; The locking unit is connected in parallel at both ends of the auxiliary contact, and is used to: switch its own switch state to open when the detection unit detects that the AC bus is energized; and switch its own switch state to closed when the detection unit detects that the AC bus is de-energized.

2. The grid-connected and off-grid switching control circuit according to claim 1, characterized in that: The detection locking module is a relay; Among them, the coil of the relay is the detection unit in the detection and locking module, the contact of the relay is the locking unit, and the contact of the relay is a normally closed contact.

3. The grid-connected and off-grid switching control circuit according to claim 1, characterized in that: The buttons include: a closing button and an opening button; Then the switch unit comprises: a closing switch and an opening switch; The closing switch is connected in series in the parallel branch where the auxiliary contact is located, and the closing switch is a normally open switch; The opening switch is connected in series in the main circuit of the controlled circuit, and the opening switch is a normally closed switch; The control circuit is used to: close the closing switch when the closing button is pressed; and open the opening switch when the opening button is pressed.

4. The on-grid and off-grid switching control circuit according to claim 1, characterized in that: There is one button; The control loop is used to switch and maintain the switch state of the switch unit when the button is pressed.

5. The grid-connected and off-grid switching control circuit according to any one of claims 1 to 4, characterized in that: The controlled frame circuit breaker is a frame circuit breaker on the power grid side.

6. The on-grid and off-grid switching control circuit according to claim 5, characterized in that: The power source in the controlled loop is a power grid.

7. The on-grid and off-grid switching control circuit according to any one of claims 1 to 4, characterized in that: The controlled frame circuit breaker is a frame circuit breaker on the energy storage converter side.

8. The on-grid and off-grid switching control circuit according to claim 7, characterized in that: The power source in the controlled loop is an energy storage converter.

9. A grid-connected and off-grid switching cabinet, characterized in that: It comprises the on-grid and off-grid switching control circuit as described in any one of claims 1 to 8.

10. The grid-connected and off-grid switching cabinet according to claim 9, characterized in that: The number of the on-grid and off-grid switching control circuits is two, and the two on-grid and off-grid switching control circuits respectively use the frame circuit breakers on the grid side and the energy storage converter side as controlled frame circuit breakers.

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