And off-grid switching system and energy storage system

Abstract

The application discloses a parallel and off-grid switching system and an energy storage system, and belongs to the technical field of power electronics. The parallel and off-grid switching system comprises at least two switching switch devices in parallel, one switching switch device in the at least two switching switch devices is configured as a master, other switching switch devices in the at least two switching switch devices are configured as slaves, and the master and the slaves are in communication connection; the master sends control information to the slaves; the slaves control based on the control information, so that the slaves follow the actions of the master. The parallel and off-grid switching system can improve the stability of the switching process of multiple switching switch devices, and is beneficial to the continuity of power supply and the stable operation of loads.

Description

Technical Field

[0001] This application belongs to the field of power electronics technology, and in particular relates to a grid-connected / off-grid switching system and an energy storage system. Background Technology

[0002] Automatic Transfer System (ATS) is used in microgrid systems. When the grid fails or the energy storage system needs to operate independently, the ATS can quickly disconnect from the grid. After the system switches to islanded operation, it quickly establishes the microgrid voltage to ensure uninterrupted power supply to the load. When the grid resumes normal power supply or the system needs to be connected to the grid according to actual conditions, the ATS can connect the energy storage system to the grid.

[0003] As microgrid systems expand in scale, the number of integrated power units, including energy storage, renewable energy generation, and diesel generators, is increasing, leading to a corresponding increase in the number of ATS (Automatic Transfer Switches) configured for both on-grid and off-grid operation. The instability of multiple ATS during switching processes affects the continuity of power supply and the stable operation of the load within the microgrid system. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a grid-connected / off-grid switching system and an energy storage system that can improve the stability of the switching process of multiple switching devices.

[0005] Firstly, this application provides a system for switching between on-grid and off-grid operations, comprising:

[0006] At least two switching devices connected in parallel, wherein one of the at least two switching devices is configured as a master device and the other switching devices are configured as slave devices, and the master device and the slave device are communicatively connected;

[0007] The host sends control information to the slave; the slave performs control based on the control information so that it follows the actions of the host.

[0008] According to the grid-connected switching system of this application, by setting multiple parallel switching devices as master-slave control strategies, the master sends control information to the slave, and the slave controls its own actions according to the received control information, so that the slave follows the master's actions, which can improve the stability of the switching process of multiple switching devices and is beneficial to the continuity of power supply and the stable operation of the load.

[0009] According to one embodiment of this application, the control information includes switch control information. The host sends the switch control information to the slave based on its own switch state. The slave controls its own switch action based on the switch control information so that the switch state of the slave follows the switch state of the host.

[0010] According to one embodiment of this application, the control information includes operating mode information, and the host further sends the operating mode information to the slave based on its own operating mode; the slave controls its own operating mode based on the operating mode information so that the slave's operating mode follows the host's operating mode.

[0011] According to one embodiment of this application, the host is further configured to send first status information to the slave based on the host's own operating status;

[0012] The slave device is also used to send fault detection information of the slave device to the master device based on its own operating status and the first status information.

[0013] According to one embodiment of this application, the slave device is further configured to send second status information to the master device based on its own operating status;

[0014] The host is also used to determine the fault detection information of the slave device based on its own operating status and the second status information.

[0015] According to one embodiment of this application, the on-grid / off-grid switching system shuts down based on the fault detection information of the slave device.

[0016] According to one embodiment of this application, based on the fault detection information of the slave device, the parallel-to-offline switching system switches off the faulty slave device, while the switching devices in the parallel-to-offline switching system other than the faulty slave device remain in operation.

[0017] According to one embodiment of this application, the fault detection information of the slave device includes switch status detection results and / or operating current detection results;

[0018] The switch status detection results are inconsistent, indicating a slave device malfunction;

[0019] The operating current detected by the operating current detection is inconsistent, indicating a slave device malfunction.

[0020] According to one embodiment of this application, the grid-connected switching system is used in an energy storage system, and the grid-connected switching system is also used to communicate with the energy management system of the energy storage system. The host is used to receive control signals from the energy management system and control the switching action of the host itself.

[0021] According to one embodiment of this application, the host is further configured to send its own status information and the fault detection information of the slave to the energy management system, and the slave is further configured to send its own status information to the energy management system.

[0022] According to one embodiment of this application, the host is configured to operate in stand-alone mode when communication failure protection is triggered; the slave is configured to operate in stand-alone mode when communication failure protection is triggered.

[0023] According to one embodiment of this application, when the number of hosts in the on-grid / off-grid switching system is not one, the host and the slave trigger communication fault protection.

[0024] According to one embodiment of this application, the host is used to control the switching action of the host itself according to the operating logic of the stand-alone mode.

[0025] According to one embodiment of this application, the host is used to control the grid-side switch of the host to close when the grid connected to the grid-connected switching system is normal, and the host is used to control the grid-side switch of the host to open when the grid connected to the grid-connected switching system is abnormal.

[0026] Secondly, this application provides an energy storage system, comprising:

[0027] At least two energy storage converters;

[0028] As described in the first aspect above, in the grid-connected / off-grid switching system, a switching device is connected to at least one of the energy storage converters.

[0029] According to the energy storage system of this application, by setting multiple parallel switching devices as a master-slave control strategy, the master sends control information to the slave, and the slave controls its own actions according to the received control information, so that the slave follows the master's actions, which can improve the stability of the switching process of multiple switching devices, and achieve seamless on-grid and off-grid switching in cooperation with the off-grid switching system and energy storage converter.

[0030] According to one embodiment of this application, the switching device is connected to the load port, the new energy port and the diesel generator port. The host of the grid-connected switching system controls its own switching action based on the state of the grid to which the grid-connected switching system is connected, as well as the state of the load port, the new energy port and the diesel generator port.

[0031] Additional aspects and advantages of this application 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 this application. Attached Figure Description

[0032] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0033] Figure 1 This is one of the structural schematic diagrams of the on-grid / off-grid handover system provided in the embodiments of this application;

[0034] Figure 2 This is a second schematic diagram of the on-grid / off-grid switching system provided in the embodiments of this application;

[0035] Figure 3 This is a schematic diagram of the master-slave communication process in the on-grid / off-grid switching system provided in the embodiments of this application;

[0036] Figure 4 This is a schematic diagram of the fault detection process of the on-grid / off-grid switching system provided in the embodiments of this application.

[0037] Figure label:

[0038] Switching device 100, main unit 110, slave unit 120,

[0039] Energy storage converter 210, load port 220, new energy port 230, diesel generator port 240.

[0040] Grid 300, energy management system 400. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0042] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0043] The grid-connected / off-grid switching system and energy storage system provided in this application will be described in detail below with reference to the accompanying drawings and through specific embodiments and application scenarios.

[0044] like Figure 1 As shown, the grid-connected / off-grid switching system of this application embodiment includes at least two switching devices 100 connected in parallel.

[0045] The grid connection and off-grid switching system can be applied to microgrid systems. When the grid 300 fails or the microgrid system needs to operate independently, the connection with the grid 300 is disconnected through the grid connection and off-grid switching system. When the grid 300 resumes normal power supply or the microgrid system needs to be connected to the grid according to actual conditions, the grid connection and off-grid switching system can connect the microgrid system to the grid 300.

[0046] Among them, a microgrid system is a small-scale power generation and distribution system that integrates distributed power sources, energy storage devices, energy conversion devices, loads, and monitoring and protection devices.

[0047] The grid-connected and off-grid switching system includes at least two switching devices 100 connected in parallel. The at least two switching devices 100 can be connected in parallel between the microgrid system and the power grid 300 to realize the on / off control of the electrical connection between the microgrid system and the power grid 300.

[0048] The switching device 100 can be an automatic transfer system (ATS).

[0049] In actual implementation, the switching device 100 can be composed of multiple switching devices. When one of the power sources connected to the switching device 100 fails or is interrupted, the switch can be switched to another power source by controlling the switch action, thus ensuring the continuity and stability of the power supply.

[0050] Taking the switching device 100 as an ATS as an example.

[0051] The on-grid and off-grid switching system includes n switching devices 100, namely ATS-1, ATS-2, ..., ATS-n, which are connected in parallel.

[0052] In this embodiment, one side of the switching device 100 is connected to the power grid 300, and the other side of the switching device 100 is connected to the load port 220, the new energy port 230 and the diesel generator port 240. The on and off of the electrical connections are controlled by circuit breakers QF4, QF5 and QF2 respectively.

[0053] Among them, load port 220 is connected to the load, new energy port 230 is connected to the new energy power generation device (e.g., photovoltaic power generation device), and diesel power generation port 240 is connected to the diesel power generation device.

[0054] The switching device 100 can also be connected to the energy storage converter 210, and the switching device 100 can also include circuit breakers QF1, QF2 and thyristor SCR switches.

[0055] In actual use, the switching device 100 can be used with one energy storage converter 210, or with two or more energy storage converters 210.

[0056] One of the at least two switching devices 100 is configured as a master device 110, and the other switching devices 100 are configured as slave devices 120, with the master device 110 and the slave device 120 being communicatively connected.

[0057] The on-grid switching system is set to a master-slave control strategy, with one switching device 100 configured as the master 110 and other switching devices 100 configured as slaves 120. Communication is achieved between the master 110 and the slave 120 to enable the parallel operation of at least two switching devices 100.

[0058] In this embodiment, the host 110 sends control information to the slave 120; the slave 120 performs control based on the control information so that the slave 120 follows the actions of the host 110.

[0059] In actual implementation, the grid-connected and off-grid switching system operates in parallel mode. Parallel mode refers to the mode in which multiple switching devices 100 connected in parallel in the grid-connected and off-grid switching system work together. In parallel mode, multiple switching devices 100 can share the power supply and load, improving the continuity and reliability of power supply.

[0060] In this embodiment, in parallel mode, the grid-connected switching system can operate in parallel with the grid. Multiple switching devices 100 follow the control strategies of the host 110 and the slave 120. The host 110 sends control information to the slave 120, and the slave 120 performs control according to the control information. The slave 120 follows the actions of the host 110, thereby realizing the synchronous control of the grid-connected switching system.

[0061] In actual implementation, the parallel-to-offline switching system can also operate offline. Multiple switching devices 100 follow the control strategies of the host 110 and the slave 120. The host 110 sends control information to the slave 120, and the slave 120 performs control according to the control information. The slave 120 follows the actions of the host 110 to realize the synchronous control of the parallel-to-offline switching system.

[0062] It should be noted that the control information is used to control the operation of the switching device 100, which is the slave device 120. The control information sent by the master device 110 to the slave device 120 can be switch control information to control the switching operation of the switching device 100; the control information sent by the master device 110 to the slave device 120 can also be operating mode information to control the operating mode of the switching device 100.

[0063] In some embodiments, the control information includes switch control information. The host 110 sends the switch control information to the slave 120 based on its own switch state. The slave 120 controls its own switch action based on the switch control information so that the switch state of the slave 120 follows the switch state of the host 110.

[0064] It should be noted that in the grid-connected and off-grid switching system, the slave device 120 controls the operation of its own circuit breaker, thyristor and other switches according to the switch control information. The slave device 120 only receives the switch control information from the master device 110 and controls the switch operation to follow the switch state of the master device 110. The control logic of the slave device 120 is simple and can effectively improve the switching speed.

[0065] In the on-grid / off-grid switching system, the host 110 generates switching control information based on its own switching state and sends the switching control information to the slave 120. The slave 120 controls its own switching action based on the received switching control information, and the switching state of the slave 120 changes with the switching state of the host 110.

[0066] In actual operation, the host 110 can send switch control information to the slave 120 through high-speed communication, which can reduce the time error between the host and slave during the switch switching process. This allows the switching actions of each switching device 100 in the grid-connected and off-grid switching system to be synchronized, avoiding power outages or equipment damage caused by asynchronous switching.

[0067] For example, the master 110 and the slave 120 are connected via CAN communication. The master 110 can send switch control information to the slave 120 at intervals of 5*31.25us to reduce the time error between the master and slave actions and ensure that the master and slave switch states are consistent.

[0068] It should be noted that in CAN communication, switch control information can be represented as control words in CAN communication frames.

[0069] In this embodiment, the circuit breakers, thyristors, and other switches of the slave unit 120 follow the switching actions of the master unit 110. The switching control information sent by the master unit 110 may include grid-side circuit breaker control words, diesel generator-side circuit breaker control words, thyristor control words, fan control words, etc. After being transmitted to the slave unit 120, the slave unit 120 controls the switching actions according to these control words.

[0070] In some embodiments, the control information includes operating mode information. The host 110 is also used to send the operating mode information to the slave 120 based on its own operating mode. The slave 120 is used to control its own operating mode based on the operating mode information so that the operating mode of the slave 120 follows the operating mode of the host 110.

[0071] The operating mode may include information such as the operating mode and power status of the switching device 100.

[0072] In actual operation, the operating modes of the switching device 100 may include shutdown, grid connection, off-grid, bypass, state switching, etc.

[0073] The power status of the switching device 100 is used to characterize the status of the main power supply, backup power supply, etc. connected to the switching device 100. For example, the main power grid 300 connected to the switching device 100 is normal, and the backup power energy storage device is allowed to switch.

[0074] In this embodiment, the host 110 also sends operating mode information to the slave 120. The slave 120 adjusts its own operating mode according to the operating mode information. The operating mode of the slave 120 changes with the operating mode of the host 110, so that the slave 120 can maintain the same state as the host 110.

[0075] Taking the switching device 100 as an ATS, and the control information including switch control information as an example.

[0076] The on-grid and off-grid switching system includes n switching devices 100, namely ATS-1, ATS-2, ..., ATS-n, which are connected in parallel. ATS-1 is the master device 110, and ATS-2, ..., ATS-n are slave devices 120.

[0077] In this embodiment, QF1 and QF3 of ATS-1 are disconnected, while SCR, QF4, QF5 and QF2 are closed, and ATS-1 sends switch control information to ATS-2, ..., ATS-n.

[0078] ATS-2, ..., ATS-n disconnect QF1 and QF3 and close SCR, QF4, QF5 and QF2 according to the received switch control information, following the switching state of ATS-1.

[0079] It should be noted that the grid-connected and off-grid switching system is designed for complex microgrid systems with energy storage, photovoltaic and diesel power generation. It enables the parallel operation of multiple switching devices 100, improves system maintainability, reduces the risk of load power outages, and improves the stability of seamless switching of the grid-connected and off-grid switching system. When a new switching device 100 is added, the newly added switching device 100 can be configured as a slave device 120. The system capacity can be increased without redesigning. The expansion is simple, the design cost is low and the utilization rate is high.

[0080] According to the on-grid switching system provided in the embodiments of this application, by setting multiple parallel switching devices 100 as master-slave control strategies, the master 110 sends control information to the slave 120, and the slave 120 controls its own actions according to the received control information, so that the slave 120 follows the master 110. This can improve the stability of the switching process of multiple switching devices 100, which is beneficial to the continuity of power supply and the stable operation of the load.

[0081] In some embodiments, the host 110 is further configured to send first status information to the slave 120 based on its own operating status; the slave 120 is further configured to send fault detection information of the slave 120 to the host 110 based on its own operating status and the first status information.

[0082] The operating state refers to the state of the switching device 100 during its operation, which describes the current, voltage, and on / off states of the switching device 100.

[0083] In actual operation, the host 110 sends first status information to the slave 120. The first status information may include the host 110's current, voltage, switch on / off status information, etc.

[0084] In this embodiment, the slave device 120 has a fault detection function. The slave device 120 can compare its own operating state with the operating state of the master device 110 based on the first state information to determine whether the current, voltage, switch on / off status, etc. of the master and slave devices are consistent, detect whether the slave device 120 itself has a fault, and send the fault detection information of the slave device 120 to the master device 110.

[0085] It should be noted that the fault detection information of slave device 120 is information that indicates whether slave device 120 has a fault and the corresponding fault type.

[0086] In CAN communication, the fault detection information of slave device 120 can be represented as a fault word in the CAN communication frame. When a certain switch of slave device 120 is inconsistent with the corresponding switch of master device 110, that is, when the switch of slave device 120 is faulty, the character corresponding to the switch in the CAN communication frame is set to the fault bit.

[0087] In some embodiments, the slave device 120 is further configured to send second status information to the master device 110 based on its own operating status; the master device 110 is further configured to determine the fault detection information of the slave device 120 based on its own operating status and the second status information.

[0088] In actual operation, the slave device 120 sends second status information to the master device 110. The second status information may include the current, voltage, switch on / off status information of the slave device 120.

[0089] In this embodiment, the host 110 has a fault detection function. The host 110 can compare its own operating status with that of the slave 120 based on the second status information sent by the slave 120, determine whether the current, voltage, switch on / off status, etc. of the host and slave are consistent, detect whether the slave 120 has failed, and obtain the fault detection information of the slave 120.

[0090] In some embodiments, the fault detection information of the slave device 120 includes switch status detection results and operating current detection results.

[0091] Among them, the switch status detection result is used to characterize whether the switch status between the master and slave is consistent. For example, the switch status detection result can include whether the status of the grid-side circuit breaker, the diesel generator-side circuit breaker, the thyristor, etc., between the master and slave is consistent.

[0092] The working current detection result is used to characterize whether the working current between the master and slave devices is consistent. Consistent working current means that the current difference on the corresponding circuit is within the preset differential current range.

[0093] In this embodiment, if the switch status detection results are inconsistent, the slave device 120 is faulty; if the operating current detection results are inconsistent, the slave device 120 is also faulty.

[0094] For example, slave device 120 compares its own load current and thyristor current with the load current and thyristor current of master device 110 respectively. When the difference between the load current or the difference between the thyristor current between the master and slave devices exceeds the preset difference range, the working current of the working current detection result in the fault detection information of slave device 120 is inconsistent, indicating that slave device 120 has a fault.

[0095] For example, slave device 120 compares its own thyristor status with that of master device 110. When the thyristor statuses of the master and slave devices are inconsistent, slave device 120's thyristor is turned off and master device 110's thyristor is turned on, or slave device 120's thyristor is turned on and master device 110's thyristor is turned off. If the switch status detection results in the fault detection information of slave device 120 are inconsistent, it indicates that slave device 120 has a fault.

[0096] In this embodiment, the on-grid and off-grid switching system has functions such as inconsistent switch status and differential current protection. Through the first status information, the second status information and the fault detection information of the slave 120, the host 110 can determine whether the slave 120 has a fault.

[0097] It should be noted that the slave device 120 can be configured with its own fault detection logic such as overcurrent and overload, and upload the corresponding fault information to the host device 110 to indicate that there is a fault in the slave device 120 in the host device 110 system.

[0098] In some embodiments, the system is shut down by switching off from the network based on the fault detection information of the slave device 120.

[0099] In this embodiment, the host 110 is used to shut down the system when it is determined that there is a fault in the slave 120 in the off-network switching system based on the fault detection information of the slave 120.

[0100] When the host 110 detects a fault in the slave 120, the host 110 shuts down. After shutting down, the host 110 no longer sends switch control information, operating mode information, first status information, etc. to each slave 120, and the off-network switching system shuts down.

[0101] In actual operation, fault detection information of the faulty slave device 120 can be output to prompt maintenance. After the fault is cleared by the slave device 120, the slave device 120 reports to the master device 110 that the fault has been cleared. The master device 110 resets the fault bit of the corresponding slave device 120 and transmits the fault clearing command to the slave device 120. The master device 110 and the slave device 120 resume operation and switch the system to parallel operation mode.

[0102] The following is a specific example.

[0103] Host 110 executes Figure 3 The steps shown in the flowchart on the left are executed by slave device 120. Figure 3 The steps in the flowchart on the right are shown.

[0104] like Figure 3 As shown, the host 110 performs a parallel operation enable judgment. After confirming that it is running in parallel operation mode, it performs a host 110 role judgment. After confirming that it is the host 110, it sends a control word and status information to the slave 120. The control word is the switch control information, and the status information sent by the host 110 to the slave 120 is the first status information.

[0105] Slave 120 performs a parallel operation enable judgment. After confirming that it is running in parallel operation mode, it performs a slave 120 role judgment. After confirming that it is slave 120, it receives the control word and status information sent by master 110, controls its own switching action according to the control word, compares the status information with its own operating status, obtains its own fault detection information, and generates the corresponding fault word.

[0106] The slave device 120 sends the fault word and status information (second status information) to the master device 110. The master device 110 judges the fault status of the slave device 120 in the offline switching system based on the fault word and status information of the slave device 120.

[0107] like Figure 4 As shown, the master 110 or slave 120 can determine whether there is a fault in the slave 120 through status information. The fault detection process may include detecting whether the thyristor current is consistent between the master and slave, whether the load current is consistent between the master and slave, whether the thyristor status is consistent between the master and slave, and whether the circuit breaker status is consistent. When inconsistency occurs, the fault bit is set and the corresponding fault detection information is reported.

[0108] In some embodiments, based on the fault detection information of slave device 120, the off-grid switching system switches out the faulty slave device 120, and the switching device 100 in the off-grid switching system other than the faulty slave device 120 continues to operate.

[0109] In this embodiment, the host 110 is used to disconnect the faulty slave 120 from the network and switch the system when it is determined that there is a fault in the slave 120 based on the fault detection information of the slave 120, while the remaining slaves 120 and the host 110 continue to operate.

[0110] In some embodiments, the grid-connected switching system is used in the energy storage system and is also used to communicate with the energy management system 400 of the energy storage system. The host 110 is used to receive control signals from the energy management system 400 and control the switching action of the host 110 itself.

[0111] Among them, the Energy Management System 400 (EMS) can monitor and manage the operating status of the energy storage system, control the charging and discharging operations of the energy storage system, realize the distribution and utilization of energy, and ensure the stable operation of the microgrid system.

[0112] In this embodiment, the host 110 and slave 120 in the on-grid switching system are communicatively connected to the energy management system 400. The host 110 can receive control signals from the energy management system 400. The host 110 controls the switch action according to the control signals. The host 110 sends switch control information to the slave 120. The slave 120 controls the switch action according to the switch control information, so that the switch state of the slave 120 changes with the switch state of the host 110.

[0113] In some embodiments, the host 110 is further configured to send its own status information and the fault detection information of the slave 120 to the energy management system 400, and the slave 120 is further configured to send its own status information to the energy management system 400.

[0114] The host 110 can also send fault detection information of the slave 120 to the energy management system 400, and report and switch off-grid faults in the system.

[0115] like Figure 2 As shown, the host 110 can receive control signals from the energy management system 400, and the host 110 can also send status information to the energy management system 400. The slave 120 only sends status information to the energy management system 400 and does not receive control signals from the energy management system 400. This can effectively reduce the control burden of the energy management system 400 and prevent the long grid connection and disconnection cycle control time of the energy management system 400 from affecting the operational stability of the grid connection and disconnection switching system.

[0116] In actual implementation, the host 110 may include two processors, DSP and ARM, and the slave 120 may also include two processors, DSP and ARM. The host 110 and slave 120 communicate with the energy management system 400 through the ARM, and the host 110 and slave 120 communicate with each other through the DSP processor using CAN communication signals.

[0117] In some embodiments, the host 110 is configured to operate in stand-alone mode when communication failure protection is triggered; the slave 120 is configured to operate in stand-alone mode when communication failure protection is triggered.

[0118] In this embodiment, when the host 110 or slave 120 triggers the communication fault protection, it indicates that the communication function between the host 110 and slave 120 cannot be realized normally, and it is difficult to guarantee the validity of information such as switch control information, operating mode information, first status information, second status information and fault detection information. The host 110 or slave 120 can operate in the stand-alone mode of a single switching device 100 and autonomously disconnect the circuit breaker, thyristor and other switches of the switching device 100.

[0119] In actual implementation, communication failures can be detected and handled by methods such as global cumulative variables and heartbeat frame response frames. When a communication failure occurs, the host 110 or slave 120 triggers communication failure protection.

[0120] For example, when host 110 and slave 120 are connected, a global variable can be incremented in an external task during communication between host 110 and slave 120. This variable is cleared to zero in the fast frame function of communication between host 110 and slave 120 and the slow frame function of communication between slave 120 and host 110. If the global variable is detected externally and exceeds a certain value for a period of time, it indicates that a communication failure has occurred, and host 110 or slave 120 triggers communication failure protection.

[0121] In some embodiments, when the number of hosts 110 in the on-grid / off-grid switching system is not one, the host 110 and slave 120 trigger communication fault protection.

[0122] During the communication between the host 110 and the slave 120, the number of hosts 110 in the parallel-to-offline switching system can be verified. When the number of hosts 110 in the parallel-to-offline switching system is one, it indicates that the address settings of the host 110 and the slave 120 in the parallel-to-offline switching system are correct and they can communicate normally.

[0123] When the number of hosts 110 in the parallel-to-offline switching system is not one, it indicates that the address settings of hosts 110 and slaves 120 in the parallel-to-offline switching system are incorrect, and the parallel-to-offline switching system has a communication failure.

[0124] In this embodiment, the parallel-to-offline switching system does not allow a situation where there is more than one host 110, nor does it allow a situation where there is no host 110. By verifying the number of hosts 110 in the parallel-to-offline switching system, communication fault protection is triggered, thereby improving the stability of the parallel-to-offline switching system.

[0125] In some embodiments, the host 110 is used to control its own switching actions according to the stand-alone mode operating logic.

[0126] In this embodiment, the host 110 operates according to the preset stand-alone mode operating logic, controls the host 110's own switching action, and sends switching control information to the slave 120 according to its own switching state, so that the switching state of the slave 120 follows the switching state of the host 110.

[0127] Among them, the single-machine mode refers to the operating mode in which a single switching device 100 autonomously disconnects circuit breakers, thyristors and other switches.

[0128] It should be noted that the switching device 100 operates in stand-alone mode. When the power grid 300 fails or the microgrid system needs to operate independently, the switching device 100 can quickly disconnect from the power grid 300. When the power grid 300 restores normal power supply or the microgrid system needs to be connected to the grid, the switching device 100 can establish a connection between the microgrid system and the power grid 300, achieving seamless on-grid and off-grid switching and ensuring stable operation of the load.

[0129] In some embodiments, the host 110 is used to control the grid-side switch of the host 110 to close when the grid 300 connected to the grid-connected switching system is normal, and the host 110 is used to control the grid-side switch of the host 110 to open when the grid 300 connected to the grid-connected switching system is abnormal.

[0130] In this embodiment, when the grid 300 connected to the grid-connected switching system is normal, the grid-side switch of the host 110 is closed, the host 110 sends switch control information to the slave 120, and the grid-side switch of the slave 120 closes in accordance with the grid-side switch of the host 110.

[0131] When the grid 300 connected to the grid switching system is abnormal, the grid-side switch of the host 110 is disconnected, and the host 110 sends switch control information to the slave 120. The grid-side switch of the slave 120 is disconnected following the grid-side switch of the host 110.

[0132] Taking the switching device 100 as an ATS as an example.

[0133] The on-grid and off-grid switching system includes n switching devices 100, namely ATS-1, ATS-2, ..., ATS-n, which are connected in parallel. ATS-1 is the master device 110, and ATS-2, ..., ATS-n are slave devices 120.

[0134] In this embodiment, when the grid 300 connected to the grid-connected switching system is normal, the grid-side switch QF1 of ATS-1 is closed, and ATS-1 sends switch control information to ATS-2, ..., ATS-n, so that the grid-side switches QF1 of ATS-2, ..., ATS-n close in accordance with the grid-side switch QF1 of ATS-1.

[0135] When the grid connected to the off-grid switching system is abnormal (300), the grid-side switch QF1 of ATS-1 is opened. ATS-1 sends switch control information to ATS-2, ..., ATS-n, causing the grid-side switches QF1 of ATS-2, ..., ATS-n to open along with the grid-side switch QF1 of ATS-1.

[0136] It is understandable that the switching action of the switching device 100 is accompanied by a change in the operating mode of equipment such as energy storage, new energy power generation, diesel power generation, and load.

[0137] For example, ATS-1 is the main unit 110. ATS-1 operates in stand-alone mode. When the grid 300 is normal, the grid-side switch QF1 is closed, the thyristor SCR is turned on, the energy storage converter 210 is connected to the grid in PQ mode, and the photovoltaic inverter connected to the new energy port 230 is also connected to the grid in PQ mode.

[0138] When the grid 300 is abnormal, ATS-1 cuts off the thyristor SCR and disconnects from the grid 300. The energy storage converter 210 detects the grid 300 abnormality and switches to VSG mode for off-grid operation to support the microgrid voltage. With the support of the energy storage converter 210, the photovoltaic inverter continues to operate in PQ mode in grid-connected mode. When the state of charge of the energy storage system corresponding to the energy storage converter 210 is too low, the diesel generator at the diesel generator port 240 is connected to supply power to the microgrid.

[0139] When the grid 300 is restored, the energy management system 400 determines whether the grid connection conditions are met based on the grid-side voltage. If the grid connection conditions are met, the grid-side switch QF1 is closed, and then synchronization is performed. After the conditions are met, the thyristor SCR is closed, and the energy storage converter 210 operates in VSG mode in grid connection. After the operation is stable, the energy storage converter 210 switches to PQ mode.

[0140] In this embodiment, the host 110 sends switch control information to the slave 120, and the slave 120 follows the host 110's actions. The seamless parallel-to-offline switching in parallel mode is simple and easy to implement, and is suitable for expansion needs under different seamless parallel-to-offline switching strategies, which greatly reduces the development and maintenance costs of the parallel-to-offline switching system.

[0141] This application also provides an energy storage system.

[0142] The energy storage system includes at least two energy storage converters 210 and a grid-connected / off-grid switching system as described above. The grid-connected / off-grid switching system includes at least two switching devices 100 connected in parallel, and one switching device 100 is connected to at least one energy storage converter 210.

[0143] In actual use, the switching device 100 can be used with one energy storage converter 210, or with two or more energy storage converters 210.

[0144] One of the at least two switching devices 100 is configured as a master device 110, and the other switching devices 100 are configured as slave devices 120, with the master device 110 and the slave device 120 being communicatively connected.

[0145] In this embodiment, when the on-grid switching system is operating in parallel mode, the host 110 sends control information to the slave 120 based on its own on / off state, and the slave 120 performs control based on the control information so that the slave 120 follows the actions of the host 110.

[0146] In some embodiments, the switching device 100 is connected to the load port 220, the new energy port 230 and the diesel generator port 240, and the host 110 of the off-grid switching system controls its own switching action or working mode switching based on the state of the grid 300 connected to the off-grid switching system and the state of the load port 220, the new energy port 230 and the diesel generator port 240.

[0147] Among them, load port 220 is connected to the load, new energy port 230 is connected to the new energy power generation device (e.g., photovoltaic power generation device), and diesel power generation port 240 is connected to the diesel power generation device.

[0148] It is understood that the switching device 100 can be composed of multiple switching devices. When one of the power supplies connected to the switching device 100 fails or is interrupted, it can be switched to another power supply by controlling the switch action or switching the working mode, so as to ensure the continuity and stability of the power supply.

[0149] In actual implementation, the switching device 100 may include switches such as circuit breakers corresponding to the load port 220, the new energy port 230 and the diesel generator port 240, and control the on / off of the electrical connection between the switching device 100 and the load port 220, the new energy port 230 and the diesel generator port 240.

[0150] The switching device 100 may also include switches such as thyristors and circuit breakers corresponding to the power grid 300 and the energy storage converter 210, to control the on / off of the electrical connection between the switching device 100 and the power grid 300 or the energy storage converter 210.

[0151] For example, such as Figure 1 As shown, one side of the switching device 100 is connected to the power grid 300, and the other side of the switching device 100 is connected to the load port 220, the new energy port 230 and the diesel generator port 240. The on and off of the electrical connections are controlled by circuit breakers QF4, QF5 and QF2 respectively.

[0152] The switching device 100 controls the on / off connection between the grid 300 and the energy storage converter 210 via the grid-side switch QF1 and the thyristor SCR.

[0153] In some embodiments, when the grid 300 to which the energy storage system is connected is normal, the grid-side switch of the switching device 100 is closed, and the energy storage converter 210 operates in grid-connected mode.

[0154] In some embodiments, when the grid 300 to which the energy storage system is connected is abnormal, the grid-side switch of the switching device 100 is disconnected, and the energy storage converter 210 operates in off-grid mode.

[0155] In this embodiment, seamless grid-connected and off-grid switching of the energy storage system can be achieved by coordinating the switching action or working mode switching of the switching device 100 in the grid-connected and off-grid switching system with the operating mode of the energy storage converter 210.

[0156] Taking the switching device 100 as an ATS as an example.

[0157] When the grid is normal (300), the grid-side switch QF1 of the ATS is closed, the thyristor SCR is turned on, the energy storage converter 210 is connected to the grid in PQ mode, and the photovoltaic inverter connected to the new energy port 230 is also connected to the grid in PQ mode.

[0158] When the grid 300 is abnormal, the ATS cuts off the thyristor SCR and disconnects from the grid 300. The energy storage converter 210 detects the grid 300 abnormality and switches to VSG mode for off-grid operation to support the microgrid voltage. With the support of the energy storage converter 210, the photovoltaic inverter continues to operate in PQ mode in grid-connected mode. When the state of charge of the energy storage system corresponding to the energy storage converter 210 is too low, the diesel generator at the diesel generator port 240 is connected to supply power to the microgrid.

[0159] When the grid 300 is restored, the energy management system 400 determines whether the grid connection conditions are met based on the grid-side voltage. If the grid connection conditions are met, the grid-side switch QF1 is closed, and then synchronization is performed. After the conditions are met, the thyristor SCR is closed, and the energy storage converter 210 operates in VSG mode in grid connection. After the operation is stable, the energy storage converter 210 switches to PQ mode.

[0160] According to the energy storage system provided in the embodiments of this application, by setting multiple parallel switching devices 100 as master-slave control strategies, the master 110 sends control information to the slave 120, and the slave 120 controls its own actions according to the received control information, so that the slave 120 follows the actions of the master 110. This can improve the stability of the switching process of multiple switching devices 100, and enable seamless on-grid and off-grid switching in cooperation with the off-grid switching system and the energy storage converter 210.

[0161] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

[0162] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0163] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A grid-connected / off-grid handover system, characterized in that, include: At least two switching devices connected in parallel, wherein one of the at least two switching devices is configured as a master device and the other switching devices are configured as slave devices, and the master device and the slave device are communicatively connected; The host sends control information to the slave device; The slave device performs control based on the control information so that it follows the actions of the master device.

2. The on- and off-grid switching system of claim 1, wherein, The control information includes switch control information. The host sends the switch control information to the slave based on its own switch state. The slave controls its own switch action based on the switch control information so that the switch state of the slave follows the switch state of the host.

3. The on- and off-grid switching system of claim 1, wherein, The control information includes operating mode information. The host also sends the operating mode information to the slave based on its own operating mode. The slave controls its own operating mode based on the operating mode information so that the slave's operating mode follows the host's operating mode.

4. The on- and off-grid switching system of claim 1, wherein, The host is also used to send first status information to the slave based on its own operating status; The slave device is also used to send fault detection information of the slave device to the master device based on its own operating status and the first status information.

5. The on- and off-grid switching system of claim 1, wherein, The slave device is also used to send second status information to the master device based on its own operating status; The host is also used to determine the fault detection information of the slave device based on its own operating status and the second status information.

6. The on- and off-grid switching system according to claim 4 or 5, characterized in that, Based on the fault detection information of the slave device, the on-grid / off-grid switching system is shut down.

7. The on- and off-grid switching system of claim 4 or 5, wherein, Based on the fault detection information of the slave device, the parallel-to-offline switching system disconnects the faulty slave device, while the switching devices in the parallel-to-offline switching system, except for the faulty slave device, remain in operation.

8. The on- and off-grid switching system of claim 4 or 5, wherein, The fault detection information of the slave device includes the switch status detection result and / or the operating current detection result; The switch status detection results are inconsistent, indicating a slave device malfunction; The operating current detected by the operating current detection is inconsistent, indicating a slave device malfunction.

9. The on- and off-grid switching system according to any of claims 1-5, characterized by, The grid-connected / off-grid switching system is used in the energy storage system. The grid-connected / off-grid switching system is also used to communicate with the energy management system of the energy storage system. The host is used to receive control signals from the energy management system and control the switching action of the host itself.

10. The on- and off-grid switching system of claim 9, wherein, The host is also used to send its own status information and the fault detection information of the slave to the energy management system, and the slave is also used to send its own status information to the energy management system.

11. The on-grid and off-grid switching system according to any one of claims 1-5, characterized in that, The host is configured to operate in stand-alone mode when communication failure protection is triggered; the slave is configured to operate in stand-alone mode when communication failure protection is triggered.

12. The on- and off-grid switching system of claim 11, wherein, If the number of hosts in the on-grid / off-grid switching system is not one, the host and the slave will trigger communication failure protection.

13. The grid-connected / off-grid switching system according to any one of claims 1-5, characterized in that, The host is used to control its own switching actions according to the stand-alone mode operating logic.

14. The on- and off-grid switching system of claim 13, wherein, The host is used to control the grid-side switch of the host to close when the grid connected to the on-grid switching system is normal, and the host is used to control the grid-side switch of the host to open when the grid connected to the on-grid switching system is abnormal.

15. An energy storage system characterized by, include: At least two energy storage converters; The grid-connected / off-grid switching system as described in any one of claims 1-14, wherein a switching device is connected to at least one of the energy storage converters.

16. The energy storage system of claim 15, wherein, The switching device is connected to the load port, the new energy port and the diesel generator port. The host of the grid-connected and off-grid switching system controls its own switching action based on the state of the grid to which the grid-connected and off-grid switching system is connected, as well as the state of the load port, the new energy port and the diesel generator port.

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