A shutdown control method and device

Abstract

The present invention discloses a shutdown control method and device, which are applied to a system with multiple parallel inverters. The shutdown control method includes: selecting one of the multiple inverters as the master and setting the remaining inverters as slaves; in response to a first shutdown instruction, controlling the voltage of the slaves to synchronize with the grid voltage, where the grid voltage is the voltage of the master; in response to a second shutdown instruction, controlling the grid voltage to drop to a preset threshold, triggering the master and the multiple slaves to shut down. The shutdown control method provided by the present invention can control the master and slave machines to synchronously exit the network without communication.

Description

Technical Field

[0001] The present invention relates to the field of communication technologies, and in particular, to a shutdown control method and device. Background Art

[0002] A parallel system refers to a system in which multiple device nodes are independently connected to the same transmission line (such as a bus), and is widely used in various scenarios. For example, multiple uninterruptible power supplies (UPS) can form a parallel UPS system to provide stable and uninterrupted power supply for a load; for another example, multiple inverter modules of a modular UPS can also form a parallel system.

[0003] In the prior art, the parallel shutdown scheme mainly relies on parallel communication transmission. After the host receives an instruction, the host synchronizes and sends a shutdown instruction to the slave through CAN communication or other communication means to achieve the purpose of synchronous shutdown.

[0004] The inventor found that the prior art has at least the following problems: The prior art needs to achieve shutdown in the presence of communication transmission and cannot be applied to scenarios without communication. Summary of the Invention

[0005] The present invention provides a shutdown control method and device, which can control the master and slave machines to synchronously exit the network without communication.

[0006] According to one aspect of the present invention, there is provided a shutdown control method applied to a system having multiple parallel inverters. The shutdown control method includes:

[0007] Select one of the multiple inverters as the host and set the remaining inverters as slaves;

[0008] In response to a first shutdown instruction, control the voltage of the slave to synchronize with the grid voltage, where the grid voltage is the voltage of the host;

[0009] In response to a second shutdown instruction, control the grid voltage to drop to a preset threshold to trigger the shutdown of the host and the multiple slaves.

[0010] According to another aspect of the present invention, there is provided a parallel control device applied to a system having multiple parallel inverters. The parallel control device includes:

[0011] An upper computer, which is used to select one of the multiple inverters as the host and set the remaining inverters as slaves;

[0012] Slave control module, which is used to send a first shutdown instruction to the multiple slaves and control the voltages of the multiple slaves to be synchronized with the grid voltage, where the grid voltage is the voltage of the master;

[0013] Master control module, which is used to send a second shutdown instruction to the master, control the grid voltage to drop to a preset threshold, and trigger the shutdown of the master and the multiple slaves.

[0014] In addition, before responding to the second shutdown instruction, it further includes: determining whether the response information replied by the multiple slaves is received, and after determining that the response information is received, then executing the response to the second shutdown instruction. In this way, it is ensured that the slaves are ready for shutdown, thus further ensuring that the slaves can safely exit the network during the shutdown process.

[0015] In addition, controlling the voltages of the multiple slaves to be synchronized with the grid voltage includes: controlling the voltage loops of the multiple slaves to no longer receive the voltages issued by the master; selecting the grid voltage as the given value of the voltage loop.

[0016] In addition, triggering the shutdown of the master and the multiple slaves includes: monitoring in real time whether the grid voltage drops to the shutdown threshold, and when it is monitored that the grid voltage drops to the shutdown threshold, the multiple slaves and the master synchronously exit the network.

[0017] In addition, the multiple slaves include N groups of motor groups with different voltage levels, where N is an integer greater than 1; triggering the shutdown of the master and the multiple slaves includes: monitoring in real time the voltage value of the grid voltage, and when it is monitored that the grid voltage drops to a certain voltage level, all the slaves in the motor group corresponding to the voltage level synchronously exit the network; when it is monitored that the grid voltage drops to the shutdown threshold, the master exits the network.

[0018] In addition, before triggering the shutdown of the master and the multiple slaves, it further includes: obtaining the shutdown threshold according to the number of paralleled inverters and / or the phase-locking ability of the system with multiple paralleled inverters. In this way, it can further ensure that the slaves exit the network without faults.

[0019] In addition, the ratio of the shutdown threshold to the grid voltage is between 0.1 and 0.7. In this way, it can further ensure that the slaves exit the network without faults.

[0020] In addition, before responding to the first shutdown instruction, it further includes: responding to the shutdown instruction, selecting one of the multiple motors as the master, and setting the remaining motors as the multiple slaves.

[0021] In addition, both the master machine and the slave machines are energy storage converters.

[0022] Compared with the related art, the embodiments of the present invention have at least the following advantages:

[0023] First, send a first shutdown instruction to multiple slave machines, so that after receiving the first shutdown instruction, the multiple slave machines no longer receive the voltage issued by the master machine, and the voltages of the multiple slave machines are synchronized with the grid voltage; then send a second shutdown instruction to the master machine, so that after receiving the second shutdown instruction, the master machine controls the grid voltage to continuously decrease until the grid voltage drops to a preset threshold, triggering the master machine and the multiple slave machines to shut down. Since in a system with multiple parallel inverters (such as a black start scenario or a droop networking scenario), if the master machine is directly shut down, due to the unsynchronized shutdown of the master machine and the slave machines, overload or overcurrent faults will occur, bringing a large current impact to the slave machines. Therefore, in this embodiment, by setting the voltages of the multiple slave machines to be synchronized with the grid voltage, when preparing to shut down, the grid voltage is controlled to gradually decrease. At this time, the voltages of the slave machines also decrease following the decrease of the grid voltage. The shutdown process current is smooth, and there is no large current impact on the last shutdown slave machine, thereby avoiding the occurrence of overload or overcurrent phenomena, and further ensuring that the master machine and the slave machines can exit the network without faults.

[0024] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0026] Figure 1 is a flowchart of a shutdown control method provided in Embodiment 1 of the present invention;

[0027] Figure 2 is a flowchart of a shutdown control method provided in Embodiment 2 of the present invention;

[0028] Figure 3 is a flowchart of a shutdown control method provided in Embodiment 3 of the present invention;

[0029] Figure 4 is a flowchart of a shutdown control method provided in Embodiment 4 of the present invention;

[0030] Figure 5It is a voltage-time graph for implementing the shutdown control method of Embodiment 5 of the present invention;

[0031] Figure 6 It is a schematic structural diagram of the parallel control device provided according to Embodiment 5 of the present invention. Detailed implementation manners

[0032] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0033] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0034] Embodiment 1

[0035] Figure 1 A flowchart of a shutdown control method is provided for Embodiment 1 of the present invention. The shutdown control method provided in this embodiment is applied to a system with multiple parallel inverters. The system with multiple parallel inverters includes a host and multiple slaves connected in parallel with the host. Specifically, one of the multiple inverters is selected as the host, and the remaining inverters are set as slaves. As Figure 1 shown, the method includes:

[0036] S110. In response to the first shutdown instruction, control the voltages of the multiple slaves to be synchronized with the grid voltage.

[0037] Specifically, the grid voltage is the voltage of the host. In this embodiment, the voltages of the multiple slaves can be controlled to be synchronized with the grid voltage in the following manner: control the voltage loops of the multiple slaves to no longer receive the voltage issued by the host; select the grid voltage as the given value of the voltage loop.

[0038] It is worth mentioning that before the shutdown operation is performed, the master and slave machines in the system with multiple parallel inverters are not distinguished. Therefore, before the first shutdown instruction is responded to in this embodiment, it further includes: in response to the shutdown instruction, selecting one of the multiple motors as the master machine and setting the remaining motors as the multiple slave machines.

[0039] S120. In response to the second shutdown instruction, control the grid voltage to drop to a preset threshold value and trigger the shutdown of the master machine and the multiple slave machines.

[0040] Specifically, the first shutdown instruction is sent to the multiple slave machines, and the second shutdown instruction is sent to the master machine. This embodiment does not specifically limit the size of the preset threshold value, which can be set according to actual needs.

[0041] More specifically, both the master machine and the slave machines in this embodiment are energy storage converters.

[0042] Compared with the related art, in the embodiment of the present invention, the first shutdown instruction is first sent to the multiple slave machines, so that after the multiple slave machines receive the first shutdown instruction, they no longer receive the voltage issued by the master machine, and the voltages of the multiple slave machines are synchronized with the grid voltage; then the second shutdown instruction is sent to the master machine, so that after the master machine receives the second shutdown instruction, it controls the grid voltage to continuously drop until the grid voltage drops to the preset threshold value, and then triggers the shutdown of the master machine and the multiple slave machines. Since in a system with multiple parallel inverters (such as a black start scenario or a droop networking scenario), if the master machine is directly shut down, due to the asynchronous shutdown of the master machine and the slave machines, overload or overcurrent faults will occur, bringing a large current impact to the slave machines. Therefore, in this embodiment, by setting the voltages of the multiple slave machines to be synchronized with the grid voltage, when preparing to shut down, the grid voltage is controlled to gradually drop, and at this time, the voltages of the slave machines also drop following the drop of the grid voltage, thereby avoiding the occurrence of overload or overcurrent phenomena, and further ensuring that the master machine and the slave machines can withdraw from the network without faults.

[0043] Embodiment 2

[0044] Figure 2 The flowchart of a shutdown control method provided by the second embodiment of the present invention is shown. This embodiment is a further description of Embodiment 1, specifically illustrating: how to trigger the shutdown of the master machine and the multiple slave machines. As Figure 2 shown, the method includes the following steps:

[0045] S210. In response to the first shutdown instruction, control the voltages of the multiple slave machines to be synchronized with the grid voltage.

[0046] S220. In response to the second shutdown instruction, control the grid voltage to drop to the preset threshold value.

[0047] Steps S210 to S220 of this embodiment are similar to steps S110 to S120 of Embodiment 1. To avoid repetition, they will not be elaborated here.

[0048] S230: Monitor in real time whether the grid voltage drops to the shutdown threshold. When it is monitored that the grid voltage drops to the shutdown threshold, multiple slave devices and the master device synchronously exit the network.

[0049] Specifically, the ratio of the shutdown threshold to the grid voltage is between 0.1 and 0.7. A suitable shutdown threshold can be set according to the number of parallel inverters in the system and / or the phase-locking ability. In this way, it can be further ensured that the slave devices exit the network without faults.

[0050] Compared with the related art, in the embodiment of the present invention, a first shutdown command is first sent to multiple slave devices, so that after receiving the first shutdown command, the multiple slave devices no longer receive the voltage issued by the master device, and the voltages of the multiple slave devices are synchronized with the grid voltage; then a second shutdown command is sent to the master device, so that after receiving the second shutdown command, the master device controls the grid voltage to continuously drop until the grid voltage drops to a preset threshold, triggering the master device and the multiple slave devices to shut down. Since in a system with multiple parallel inverters (such as a black start scenario or a droop networking scenario), if the master device is directly shut down, since the shutdown of the master device and the slave devices cannot be synchronized, overload or overcurrent faults will occur, bringing a large current impact to the slave devices. Therefore, in this embodiment, by setting the voltages of the multiple slave devices to be synchronized with the grid voltage, when preparing to shut down, the grid voltage is controlled to gradually drop, and at this time, the voltages of the slave devices also drop following the drop of the grid voltage. The shutdown process has a smooth current and there is no large current impact on the last slave device to shut down, thus avoiding the occurrence of overload or overcurrent phenomena, and further ensuring that the master device and the slave devices exit the network without faults.

[0051] Embodiment 3

[0052] Figure 3 is a flowchart of a shutdown control method provided by Embodiment 3 of the present invention. This embodiment is a further description of Embodiment 1, specifically illustrating: how to trigger the shutdown of the master device and the multiple slave devices. As Figure 3 shown, the method includes the following steps:

[0053] S310: In response to the first shutdown command, control the voltages of multiple slave devices to be synchronized with the grid voltage.

[0054] S320: In response to the second shutdown command, control the grid voltage to drop to a preset threshold.

[0055] Steps S310 to S320 of this embodiment are similar to steps S110 to S120 of Embodiment 1. To avoid repetition, they will not be elaborated here.

[0056] S330: Monitor the voltage value of the grid voltage in real time. When it is detected that the grid voltage drops to a certain voltage level, all slave devices in the motor group corresponding to the voltage level synchronously exit the network.

[0057] Specifically, multiple slave devices include N groups of motor groups with different voltage levels, where N is an integer greater than 1. For the convenience of understanding, the following is an example of how the slave devices exit the network in this embodiment:

[0058] Suppose multiple slave devices include a total of 3 groups of motor groups 1, 2, and 3 with different voltage levels. All slave devices in motor group 1 correspond to voltage level A (that is, it has no impact on the slave devices to exit the network at voltage level A), all slave devices in motor group 2 correspond to voltage level B (that is, it has no impact on the slave devices to exit the network at voltage level B), and all slave devices in motor group 3 correspond to voltage level C (that is, it has no impact on the slave devices to exit the network at voltage level C). Assume the voltage value relationship is A > B > C. When the grid voltage drops to voltage level A, all slave devices in motor group 1 exit the network; when the grid voltage continues to drop to voltage level B, all slave devices in motor group 2 exit the network; when the grid voltage continues to drop to voltage level C, all slave devices in motor group 3 exit the network. At this time, the safe exit of all slave devices is completed.

[0059] S340: When it is detected that the grid voltage drops to the shutdown threshold, the host exits the network.

[0060] Specifically, the ratio of the shutdown threshold to the grid voltage is between 0.1 and 0.7. A suitable shutdown threshold can be set according to the number of paralleled inverters in the system and / or the phase-locked ability. In this way, it can be ensured that the host exits the network without failure.

[0061] Compared with the related technology, in the embodiment of the present invention, a first shutdown instruction is first sent to multiple slave devices, so that after receiving the first shutdown instruction, the multiple slave devices no longer receive the voltage issued by the host, and the voltages of the multiple slave devices are synchronized with the grid voltage; then a second shutdown instruction is sent to the host, so that after receiving the second shutdown instruction, the host controls the grid voltage to continuously drop until the grid voltage drops to a preset threshold, triggering the host and multiple slave devices to shut down. Since in a system with multiple paralleled inverters (such as a black start scenario or a droop networking scenario), if the host is directly shut down, due to the asynchronous shutdown of the host and the slave devices, overload or overcurrent faults will occur, bringing a large current impact to the slave devices. Therefore, in this embodiment, by setting the voltages of the multiple slave devices to be synchronized with the grid voltage, when preparing to shut down, the grid voltage is controlled to gradually drop, and at this time, the voltages of the slave devices also drop following the drop of the grid voltage, thus avoiding the occurrence of overload or overcurrent phenomena, and further ensuring that the host and the slave devices exit the network without failure.

[0062] Embodiment 4

[0063] Figure 4 The figure is a flowchart of a shutdown control method provided by Embodiment 4 of the present invention. This embodiment is a further improvement on the foregoing embodiment. Specifically, the improvement is that: before sending the second shutdown instruction, it is also necessary to determine whether response messages replied by multiple slave devices are received. After receiving the response message, the second shutdown instruction will be continued to be sent. In this way, it is ensured that the slave devices are ready for shutdown, thereby further ensuring that the slave devices can safely exit the network during the shutdown process.

[0064] As Figure 4 shown, the method includes the following steps:

[0065] S410: In response to the first shutdown instruction, control the voltages of multiple slave devices to be synchronized with the grid voltage.

[0066] S420: After receiving the response information replied by multiple slave devices, in response to the second shutdown instruction, control the grid voltage to drop to a preset threshold.

[0067] S430: Real-time monitor whether the grid voltage drops to the shutdown threshold. When it is monitored that the grid voltage drops to the shutdown threshold, multiple slave devices and the master device synchronously exit the network.

[0068] For ease of understanding, the following specifically describes the shutdown control method of this embodiment in conjunction with the attached Figure 5 :

[0069] (1) At time T1, after the local controller receives the shutdown instruction, select one energy storage converter as the master device.

[0070] (2) The local controller sets all other energy storage converters as slave devices.

[0071] (3) The local controller issues the first shutdown instruction 1.

[0072] (4) After the slave device receives the first shutdown instruction 1, the voltage loop control of the slave device no longer receives the voltage issued by the master device, selects the phase-locked external grid voltage as the voltage loop reference, and replies status 1 to the local controller, indicating that the slave device is ready to shut down.

[0073] (5) The local controller issues the second shutdown instruction 2.

[0074] (6) At time T2, after the master device receives the second shutdown instruction 2, it starts to control the grid voltage to drop. When the grid voltage drops to the preset threshold (at this time it is time T3), the shutdown process is triggered.

[0075] (7) The slave device can synchronously exit the network with the master device at time T4, or can gradually exit the network according to the voltage level between time T3 and T4.

[0076] (8) At time T4, the grid voltage drops to the shutdown threshold, and the host shuts down and exits the network.

[0077] Compared with the related art, in the embodiment of the present invention, a first shutdown instruction is first sent to multiple slave machines, so that after receiving the first shutdown instruction, the multiple slave machines no longer receive the voltage sent by the host, and the voltages of the multiple slave machines are synchronized with the grid voltage; then a second shutdown instruction is sent to the host, so that after receiving the second shutdown instruction, the host controls the grid voltage to continuously drop until the grid voltage drops to a preset threshold, triggering the host and multiple slave machines to shut down. Since in a system with multiple parallel inverters (such as a black start scenario or a droop networking scenario), if the host is directly shut down, due to the asynchronous shutdown of the host and the slave machines, overload or overcurrent faults will occur, bringing a large current impact to the slave machines. Therefore, in this embodiment, by setting the voltages of the multiple slave machines to be synchronized with the grid voltage, when preparing to shut down, the grid voltage is controlled to gradually drop, and at this time, the voltages of the slave machines also drop following the drop of the grid voltage, thus avoiding the occurrence of overload or overcurrent phenomena, and further ensuring that the host and the slave machines can exit the network without faults.

[0078] It should be understood that the various forms of the process shown above can be used, with steps reordered, added, or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitations are imposed herein.

[0079] Embodiment Five

[0080] Figure 6 is a schematic structural diagram of the parallel machine control device according to Embodiment Five of the present invention, as Figure 6 shown, the parallel machine control device includes:

[0081] A slave machine control module 1, which is used to send a first shutdown instruction to multiple slave machines and control the voltages of the multiple slave machines to be synchronized with the grid voltage, where the grid voltage is the voltage of the host; a host control module 2, which is used to send a second shutdown instruction to the host, control the grid voltage to drop to a preset threshold, and trigger the host and multiple slave machines to shut down.

[0082] It is not difficult to understand that the parallel machine control device provided by the embodiment of the present invention can execute the shutdown control method provided by any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0083] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A shutdown control method, characterized in that, Applied to a system with multiple parallel inverters, the shutdown control method includes: Select one of the multiple inverters as the master and set the remaining inverters as slaves; In response to a first shutdown instruction, control the voltage of the slaves to synchronize with the grid voltage, where the grid voltage is the voltage of the master; In response to a second shutdown instruction, control the grid voltage to drop to a preset threshold, triggering the master and the multiple slaves to shut down.

2. The shutdown control method according to claim 1, wherein Before the response to the second shutdown instruction, it further includes: Judge whether the response information replied by the multiple slaves is received. After determining that the response information is received, then execute the response to the second shutdown instruction.

3. The shutdown control method according to claim 1 or 2, wherein The control of synchronizing the voltage of the multiple slaves with the grid voltage includes: Control the voltage loop of the multiple slaves to no longer receive the voltage issued by the upper computer; Select the grid voltage as the given value of the voltage loop.

4. The shutdown control method according to claim 1, wherein The triggering of the master and the multiple slaves to shut down includes: Continuously monitor whether the grid voltage drops to the shutdown threshold. When it is monitored that the grid voltage drops to the shutdown threshold, the multiple slaves and the master synchronously exit the system.

5. The shutdown control method according to claim 1, wherein The triggering of the master and the multiple slaves to shut down includes: Continuously monitor the voltage value of the grid voltage. When it is monitored that the grid voltage drops to a certain voltage level, control all the slaves corresponding to the voltage level to synchronously exit the networking; when it is monitored that the grid voltage drops to the shutdown threshold, the master exits the system.

6. The shutdown control method according to claim 4 or 5, characterized in that Before the triggering of the master and the multiple slaves to shut down, it further includes: Obtain the shutdown threshold according to the number of parallel-connected units and / or the phase-locking ability of the system with multiple parallel inverters.

7. The shutdown control method according to claim 4 or 5, characterized in that, The ratio of the shutdown threshold to the grid voltage is between 0.1 and 0.

7.

8. The shutdown control method according to claim 1, characterized in that Before the response to the first shutdown instruction, it further includes: In response to a shutdown signal, select one of the multiple inverters as the master and set the remaining inverters as the multiple slaves.

9. The shutdown control method according to claim 1, wherein Both the master and the slaves are energy storage converters.

10. A parallel control device, characterized in that, Applied to a system with multiple parallel inverters, the parallel connection control device includes: An upper computer, which is used to select one of the multiple inverters as the master and set the remaining inverters as slaves; A slave control module, which is used to send a first shutdown instruction to the multiple slaves and control the voltage of the multiple slaves to synchronize with the grid voltage, where the grid voltage is the voltage of the master; A master control module, which is used to send a second shutdown instruction to the master, control the grid voltage to drop to a preset threshold, and trigger the master and the multiple slaves to shut down.

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