Parallel operation control method and system of energy storage converter

Abstract

The invention discloses a parallel operation control method and system of an energy storage converter. The method comprises the following steps: acquiring an output current of a load end of the energy storage converter, generating a state switching signal through the main energy storage converter according to a difference between the output current and a preset current threshold value, sending the state switching signal to the ith slave energy storage converter, and sending the state switching signal to the ith slave energy storage converter through the ith slave energy storage converter. And switching the operation mode of the ith slave energy storage converter or generating an ith state signal according to the state switching signal and the operation state of the ith slave energy storage converter, and sending a state switching signal to the (i + 1) th slave energy storage converter through the main energy storage converter according to the ith state signal. According to the invention, the number of the energy storage converters in the grid-connected / off-grid mode is automatically adjusted according to the change of the load capacity, the conversion efficiency and the adaptive capability of the energy storage converters are improved, and the system benefit is maximized while the load demand of a user side is met.

Description

Technical Field

[0001] The present application relates to the field of power supply technology, and in particular to a parallel control method and system for an energy storage converter. Background Art

[0002] The power storage converter (PCS) can control the charging and discharging process of the battery, perform AC / DC conversion, and directly supply power to AC loads when there is no power grid. It is widely used in power grid operation. In practical applications, in order to ensure the stability of power supply, the power supply system usually has multiple power storage converters connected in parallel.

[0003] In the prior art, a fixed number of energy storage inverters are operated in off-grid mode and a fixed number of energy storage inverters are operated in grid-connected mode according to the load carried by the user. However, when the number of loads changes, the operating mode of the energy storage inverter needs to be manually changed to maintain the normal operation of the energy storage inverter, which has the problem of poor adaptability. Summary of the invention

[0004] The present application provides a parallel control method and system for an energy storage inverter to solve the problem in the prior art that when the number of loads changes, the operating mode of the energy storage inverter needs to be manually changed, and the adaptive capability is poor.

[0005] According to one aspect of the present application, a parallel control method for an energy storage converter is provided, which is used for a parallel control system for an energy storage converter, wherein the parallel control system for the energy storage converter includes a grid end and a load end, and n energy storage converters connected in parallel between the grid end and the load end, wherein the n energy storage converters include a master energy storage converter and n-1 slave energy storage converters; n is a positive integer greater than or equal to 2;

[0006] The parallel control method of the energy storage converter comprises:

[0007] Obtaining the output current of the load end of the energy storage converter;

[0008] Generate a state switching signal through the master energy storage converter according to the difference between the output current and a preset current threshold, and send the state switching signal to the i-th slave energy storage converter;

[0009] By means of the i-th slave energy storage converter, according to the state switching signal and the operating state of the i-th slave energy storage converter, the operating mode of the i-th slave energy storage converter is switched or the i-th state signal is generated; i is a positive integer greater than or equal to 1 and less than n-1;

[0010] The state switching signal is sent to the (i+1)th slave energy storage converter via the master energy storage converter according to the i-th state signal.

[0011] Optionally, the preset current threshold includes a first preset current threshold and a second preset current threshold;

[0012] The generating a state switching signal by the master energy storage converter according to the difference between the output current and the preset current threshold, and sending the state switching signal to the i-th slave energy storage converter comprises:

[0013] When the output current is greater than or equal to the first preset current threshold, a grid-connected to off-grid signal is generated by the master energy storage converter, and the grid-connected to off-grid signal is sent to the i-th slave energy storage converter;

[0014] When the output current is less than or equal to the second preset current threshold, an off-grid to grid-connected signal is generated by the master energy storage inverter, and the off-grid to grid-connected signal is sent to the i-th slave energy storage inverter; wherein the first preset current threshold is greater than the second preset current threshold.

[0015] Optionally, the switching of the operating mode of the i-th slave energy storage converter or generating the i-th state signal through the i-th slave energy storage converter according to the state switching signal and the operating state of the i-th slave energy storage converter comprises:

[0016] When the operation state of the i-th slave energy storage converter is the grid-connected operation state, and the state switching signal is a grid-connected to off-grid signal, the i-th slave energy storage converter is controlled to switch to the off-grid operation mode according to the grid-connected to off-grid signal;

[0017] When the operation state of the i-th slave energy storage inverter is an off-grid operation state and the state switching signal is an off-grid to grid-connected signal, the i-th slave energy storage inverter is controlled to switch to a grid-connected operation mode according to the off-grid to grid-connected signal.

[0018] Optionally, the operating state switches the operating mode of the i-th slave energy storage converter or generates the i-th state signal through the i-th slave energy storage converter according to the state switching signal and the operating state of the i-th slave energy storage converter, further comprising:

[0019] When the operation state of the i-th slave energy storage converter is an off-grid operation state, and the state switching signal is a grid-connected to off-grid signal, an off-grid state signal of the i-th slave energy storage converter is generated by the i-th slave energy storage converter according to the grid-connected to off-grid signal, and the off-grid state signal is sent to the master energy storage converter; the i-th state signal includes the off-grid state signal of the i-th slave energy storage converter;

[0020] Alternatively, when the operating state of the i-th slave energy storage inverter is a grid-connected operating state, and the state switching signal is an off-grid to grid-connected signal, the i-th slave energy storage inverter generates a grid-connected state signal of the i-th slave energy storage inverter according to the off-grid to grid-connected signal, and sends the grid-connected state signal to the master energy storage inverter; the i-th state signal also includes the grid-connected state signal of the i-th slave energy storage inverter.

[0021] Optionally, sending the state switching signal to the (i+1)th slave energy storage converter according to the i-th state signal through the master energy storage converter comprises:

[0022] When the state switching signal is a grid-connected-to-off-grid signal and the i-th state signal of the i-th slave energy storage converter is an off-grid state signal, controlling the master energy storage converter to send the grid-connected-to-off-grid signal to the i+1-th slave energy storage converter according to the off-grid state signal;

[0023] Alternatively, when the state switching signal is an off-grid to grid-connected signal and the i-th state signal of the i-th slave energy storage inverter is a grid-connected state signal, the master energy storage inverter is controlled to send the off-grid to grid-connected signal to the i+1-th slave energy storage inverter according to the grid-connected state signal.

[0024] Optionally, after switching the operation mode of the i-th slave energy storage converter according to the state switching signal and the operation state of the i-th slave energy storage converter through the i-th slave energy storage converter, the method further includes:

[0025] Obtaining the output power of the load end;

[0026] Through the master energy storage converter, it is determined whether to generate a state switching signal according to the difference between the output power and the preset power threshold, and if so, the state switching signal is sent to the (i+1)th slave energy storage converter.

[0027] Optionally, the preset power threshold includes a first preset power threshold and a second preset power threshold;

[0028] The determining, by the main energy storage converter, whether to generate a state switching signal according to a difference between the output power and a preset power threshold comprises:

[0029] When the output power is greater than or equal to the first preset power threshold, a grid-connected to off-grid signal is generated by the main energy storage converter;

[0030] When the output power is less than or equal to the second preset power threshold, an off-grid to grid-connected signal is generated by the main energy storage converter; wherein the first preset power threshold is greater than the second preset power threshold;

[0031] When the output power is greater than the second preset power threshold and less than the first preset power threshold, the main energy storage converter is controlled to stop generating a state switching signal.

[0032] Optionally, generating a state switching signal by the master energy storage converter according to a difference between the output current and a preset current threshold, and sending the state switching signal to the i-th slave energy storage converter further includes:

[0033] When the output current is greater than the second preset current threshold and less than the first preset current threshold, the main energy storage converter is controlled to stop generating a state switching signal.

[0034] According to another aspect of the present application, a parallel control system for an energy storage converter is provided, the parallel control system for the energy storage converter comprising a grid end and a load end, and n energy storage converters connected in parallel between the grid end and the load end; the n energy storage converters comprise a master energy storage converter and n-1 slave energy storage converters; n is a positive integer greater than or equal to 2;

[0035] The parallel control system of the energy storage converter also includes:

[0036] An acquisition module, used for acquiring the output current of the load end of the energy storage converter;

[0037] The master energy storage converter is used to generate a state switching signal according to the difference between the output current and the preset current threshold, and send the state switching signal to the i-th slave energy storage converter;

[0038] The i-th slave energy storage converter is used to switch the operation mode of the i-th slave energy storage converter or generate an i-th state signal according to the state switching signal and the operation state of the i-th slave energy storage converter; i is a positive integer greater than or equal to 1 and less than n-1;

[0039] The master energy storage converter is further configured to send the state switching signal to the (i+1)th slave energy storage converter according to the i-th state signal.

[0040] Optionally, the preset current threshold includes a first preset current threshold and a second preset current threshold;

[0041] The master energy storage converter is further configured to generate a grid-connected to off-grid switching signal when the output current is greater than or equal to the first preset current threshold, and send the grid-connected to off-grid switching signal to the i-th slave energy storage converter;

[0042] The master energy storage inverter is also used to generate an off-grid to grid-connected signal when the output current is less than or equal to the second preset current threshold, and send the off-grid to grid-connected signal to the i-th slave energy storage inverter; wherein the first preset current threshold is greater than the second preset current threshold.

[0043] The embodiment of the present application provides a parallel control method and system for an energy storage converter. The method includes: obtaining the output current of the load end of the energy storage converter, generating a state switching signal through the main energy storage converter according to the difference between the output current and the preset current threshold, and sending the state switching signal to the i-th slave energy storage converter, switching the operation mode of the i-th slave energy storage converter or generating the i-th state signal through the i-th slave energy storage converter according to the state switching signal and the operation state of the i-th slave energy storage converter, and sending the state switching signal to the i+1-th slave energy storage converter according to the i-th state signal through the main energy storage converter. The technical solution provided by the embodiment of the present application determines the change of the load by obtaining the output current of the load end. When the load increases / decreases, the main energy storage converter will generate a state switching signal and send the state switching signal to the i-th slave energy storage converter. The i-th slave energy storage converter determines whether it is necessary to switch the operation mode of the i-th slave energy storage converter according to the state switching signal and its own operation state. When it is not necessary to switch the operation mode of the i-th slave energy storage converter, the i-th slave energy storage converter will generate its own state signal to tell the main energy storage converter, and the main energy storage converter will continue to send the state switching signal to the i+1-th slave energy storage converter. In this way, the number of energy storage converters in the grid-connected mode / off-grid mode in multiple energy storage converters can be automatically adjusted according to the change of the user's load, so that the output of each energy storage converter is stably maintained at the preset current threshold, the conversion efficiency, service life and adaptive ability of the energy storage converter are improved, and the system benefits are maximized while meeting the user's load requirements.

[0044] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0046] Figure 1 A parallel control method for an energy storage converter provided in an embodiment of the present application;

[0047] Figure 2 A schematic structural diagram of a parallel control system for an energy storage converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0049] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0050] Figure 1 The flowchart of a parallel control method of an energy storage converter provided in an embodiment of the present application is applicable to the case of adaptive regulation of weak power grids, and can also be applied to any other power grids. The parallel control method is implemented by a parallel control system of the energy storage converter. Figure 2 A schematic diagram of a parallel control system for an energy storage converter provided in an embodiment of the present application is shown in FIG. Figure 2, the parallel control system of the energy storage converter includes a grid terminal 210 and a load terminal 220, and n energy storage converters 230 connected in parallel between the grid terminal 210 and the load terminal 220, the n energy storage converters include 1 master energy storage converter and n-1 slave energy storage converters, and the signal transmission between the master energy storage converter and the slave energy storage converter is not shown in the figure; n is a positive integer greater than or equal to 2. It can be understood that the grid terminal 210 is used to connect to the grid, and the load terminal 220 is used to connect to the load. Specifically, the grid terminal 210 can be the first input and output terminal of each energy storage converter 230, and the load terminal 220 can be the second input and output terminal of each energy storage converter 230.

[0051] The parallel control method of the energy storage converter includes:

[0052] S110, obtaining the output current of the load end of the energy storage converter.

[0053] Optionally, in one embodiment, the output current of the load end can be directly collected by the main energy storage converter; or the output current of the load end can be collected by the slave energy storage converter and then transmitted to the main energy storage converter. The main energy storage converter and the slave energy storage converter can collect the output current through current collectors such as sampling resistors or current sensors, which is not limited.

[0054] S120 , generating a state switching signal through the master energy storage converter according to the difference between the output current and the preset current threshold, and sending the state switching signal to the i-th slave energy storage converter.

[0055] Among them, the master energy storage converter is any one of the n energy storage converters and is set as the master energy storage converter, and the remaining n-1 energy storage converters are set as slave energy storage converters. The preset current threshold can be preset according to the rated current value. The state switching signal is a control signal, and its purpose is to change the operating state of the slave energy storage converter to adjust the output current. Both the master and slave energy storage converters are set with serial numbers, for example, the serial number of the master energy storage converter is set to 0, and the serial number of the slave energy storage converter is set to 1,..., n-1.

[0056] It can be understood that the change in load can be determined by the output current. When the output current is increasing, that is, when the output current is greater than the preset current threshold, it means that the load is increasing; when the output current is decreasing, that is, when the output current is less than the preset current threshold, it means that the load is decreasing; when the load increases / decreases, the main energy storage inverter will generate a state switching signal and send the state switching signal to the i-th slave energy storage inverter, thereby changing the operating state of the i-th slave energy storage inverter to adjust the number of slave energy storage inverters operating in grid-connected mode / off-grid mode among the n-1 slave energy storage inverters, so that the difference between the output current and the preset current threshold is within the target difference.

[0057] S130. Switch the operation mode of the i-th slave energy storage inverter or generate an i-th state signal through the i-th slave energy storage inverter according to the state switching signal and the operation state of the i-th slave energy storage inverter; i is a positive integer greater than or equal to 1 and less than n-1.

[0058] The operation state is divided into a grid-connected operation state and an off-grid operation state. The state switching signal includes a grid-connected to off-grid signal and an off-grid to grid-connected signal. The operation mode is divided into a grid-connected operation mode and an off-grid operation mode. The state signal includes a grid-connected state signal and an off-grid state signal.

[0059] Specifically, after the i-th slave energy storage converter receives the state switching signal sent by the main energy storage converter, the i-th slave energy storage converter switches the operation mode of the i-th slave energy storage converter or generates the i-th state signal according to its own operation state and the received state switching signal. For example, when the output current increases, the main energy storage converter will generate a grid-connected to off-grid signal and send it to the i-th slave energy storage converter. The i-th slave energy storage converter receives the grid-connected to off-grid signal sent by the main energy storage converter. If the operation state of the i-th slave energy storage converter itself is an off-grid operation state at this time, it is not necessary to perform the grid-connected to off-grid operation, and will generate its own off-grid state signal at the same time; if the operation state of the i-th slave energy storage converter itself is a grid-connected operation state at this time, the i-th slave energy storage converter will switch its own operation mode and execute the grid-connected operation mode to the off-grid operation mode. Similarly, when the output current decreases, the main energy storage inverter will generate an off-grid to grid-connected signal and send it to the i-th slave energy storage inverter. The i-th slave energy storage inverter receives the off-grid to grid-connected signal sent by the main energy storage inverter. If the i-th slave energy storage inverter is in the grid-connected state at this time, there is no need to perform the off-grid to grid-connected operation, and a grid-connected state signal of its own will be generated at the same time. If the i-th slave energy storage inverter is in the off-grid state at this time, the i-th slave energy storage inverter will switch its own operation mode and execute the off-grid operation mode to the grid-connected operation mode.

[0060] S140 . Sending a state switching signal to the (i+1)th slave energy storage converter according to the i-th state signal via the master energy storage converter.

[0061] Specifically, when the i-th slave energy storage inverter does not need to perform the operation of switching from grid-connected to off-grid / off-grid to grid-connected, it will generate an off-grid status signal / grid-connected status signal and send it to the master energy storage inverter, then the master energy storage inverter will continue to send a status switching signal to the i+1-th slave energy storage inverter; when the i-th slave energy storage inverter needs to perform the operation of switching from grid-connected to off-grid / off-grid to grid-connected, the i-th slave energy storage inverter will switch its own operating mode, and after switching its own operating mode, the master energy storage inverter will send a status switching signal to the i+1-th slave energy storage inverter; if the last n-1 slave energy storage inverters all perform the operation of switching from grid-connected to off-grid / off-grid to grid-connected and still cannot meet the requirements, the master energy storage inverter is required to perform the operation of switching from grid-connected to off-grid / off-grid to grid-connected. For example, when the output current increases, the master energy storage inverter will generate a grid-to-off-grid signal and send it to the first slave energy storage inverter. The first slave energy storage inverter receives the grid-to-off-grid signal sent by the master energy storage inverter. If the operating state of the first slave energy storage inverter itself is an off-grid operating state at this time, there is no need to perform the grid-to-off-grid operation. At the same time, it will generate its own off-grid state signal and send it to the master energy storage inverter. The master energy storage inverter will continue to send a state switching signal to the second slave energy storage inverter. If the operating state of the first slave energy storage inverter is the grid-connected operating state at this time, the first slave energy storage inverter will switch its own operating mode and execute the grid-connected operating mode to the off-grid operating mode. After the first slave energy storage inverter switches its own operating mode, the master energy storage inverter sends a state switching signal to the second slave energy storage inverter; if the last n-1 slave energy storage inverters all execute the grid-connected to off-grid / off-grid to grid-connected operations and still cannot meet the requirements, the master energy storage inverter needs to execute the grid-connected to off-grid / off-grid to grid-connected operations.

[0062] It is understandable that, in one embodiment, the master energy storage converter and each slave energy storage converter can realize signal transmission through CAN (Controller Area Network) communication, and the state switching signal and each state signal can be a CAN signal. In other embodiments, other forms of communication methods can also be used, and the state switching signal and each state signal can be corresponding communication signals under the communication method, which is not limited here.

[0063] The embodiment of the present application provides a parallel control method and system for an energy storage converter. The method includes: obtaining the output current of the load end of the energy storage converter, generating a state switching signal through the main energy storage converter according to the difference between the output current and the preset current threshold, and sending the state switching signal to the i-th slave energy storage converter, switching the operation mode of the i-th slave energy storage converter or generating the i-th state signal through the i-th slave energy storage converter according to the state switching signal and the operation state of the i-th slave energy storage converter, and sending the state switching signal to the i+1-th slave energy storage converter according to the i-th state signal through the main energy storage converter. The technical solution provided by the embodiment of the present application can determine the change of load through the output current. When the load increases / decreases, the main energy storage converter will generate a state switching signal and send the state switching signal to the i-th slave energy storage converter. The i-th slave energy storage converter determines whether it is necessary to switch the operation mode of the i-th slave energy storage converter based on the state switching signal and its own operation state. When it is not necessary to switch the operation mode of the i-th slave energy storage converter, the i-th slave energy storage converter will generate its own state signal to tell the main energy storage converter, and the main energy storage converter will continue to send the state switching signal to the i+1-th slave energy storage converter. In this way, the number of energy storage converters in the grid-connected mode / off-grid mode in multiple energy storage converters can be automatically adjusted according to the change of the user's load, so that the output of each energy storage converter is stably maintained at the preset current threshold, the conversion efficiency, service life and adaptability of the energy storage converter are improved, and the system benefits are maximized while meeting the user-side load requirements.

[0064] Optionally, the preset current threshold includes a first preset current threshold and a second preset current threshold; in one embodiment, S120 includes:

[0065] S121: When the output current is greater than or equal to a first preset current threshold, a grid-connected to off-grid signal is generated by the master energy storage converter, and the grid-connected to off-grid signal is sent to the i-th slave energy storage converter.

[0066] S122: When the output current is less than or equal to the second preset current threshold, an off-grid-to-grid signal is generated by the main energy storage inverter, and the off-grid-to-grid signal is sent to the i-th slave energy storage inverter; wherein the first preset current threshold is greater than the second preset current threshold.

[0067] Among them, in this embodiment, according to the efficiency test of the energy storage converter, it is concluded that the conversion efficiency of the energy storage converter is the highest at 40% to 80%. At the same time, the temperature of the insulated gate bipolar transistor (IGBT) is relatively low in this range, which can increase the service life of the components. In order not to affect the service life of the components and to achieve the highest conversion efficiency of the energy storage converter, 40% to 80% of the rated value is finally set as the threshold. The first preset current threshold is 80% of the load rated current, and the second preset current threshold is 40% of the load rated current. In other embodiments, it can also be changed according to the specific energy storage converter efficiency test.

[0068] Specifically, when the output current is greater than or equal to 80% of the rated current, a grid-to-off-grid signal is generated by the main energy storage inverter, and the grid-to-off-grid signal is sent to the i-th slave energy storage inverter; when the output current is less than or equal to 40% of the rated current, an off-grid-to-grid signal is generated by the main energy storage inverter, and the off-grid-to-grid signal is sent to the i-th slave energy storage inverter.

[0069] Optionally, in one embodiment, S130 includes:

[0070] S131a: When the operation state of the i-th slave energy storage inverter is the grid-connected operation state and the state switching signal is the grid-connected to off-grid signal, the i-th slave energy storage inverter is controlled to switch to the off-grid operation mode according to the grid-connected to off-grid signal.

[0071] Exemplarily, the serial number of the master energy storage converter is set to 0, and the serial number of the slave energy storage converter is set to 1, ..., n-1. When the operation state of the first slave energy storage converter is the grid-connected operation state, and the state switching signal is the grid-connected to off-grid signal, the first slave energy storage converter controls itself according to the grid-connected to off-grid signal to switch to the off-grid operation mode.

[0072] S131b: When the operation state of the i-th slave energy storage inverter is the off-grid operation state and the state switching signal is the off-grid to grid-connected signal, the i-th slave energy storage inverter is controlled to switch to the grid-connected operation mode according to the off-grid to grid-connected signal.

[0073] Exemplarily, when the operating state of the first slave energy storage inverter is an off-grid operating state and the state switching signal is an off-grid to grid-connected signal, the first slave energy storage inverter controls itself to switch to the grid-connected operating mode according to the off-grid to grid-connected signal.

[0074] Optionally, in one embodiment, S130 further includes:

[0075] S132a. When the operation state of the i-th slave energy storage inverter is the off-grid operation state and the state switching signal is the grid-connected to off-grid signal, the i-th slave energy storage inverter generates an off-grid state signal of the i-th slave energy storage inverter according to the grid-connected to off-grid signal, and sends the off-grid state signal to the master energy storage inverter.

[0076] The i-th state signal includes an off-grid state signal of the i-th slave energy storage converter and a grid-connected state signal of the i-th slave energy storage converter.

[0077] Exemplarily, when the operating state of the first slave energy storage inverter is an off-grid operating state and the state switching signal is a grid-connected to off-grid signal, the first slave energy storage inverter generates an off-grid state signal of the first slave energy storage inverter according to the grid-connected to off-grid signal, and sends the off-grid state signal to the master energy storage inverter.

[0078] or,

[0079] S132b. When the operation state of the i-th slave energy storage inverter is the grid-connected operation state and the state switching signal is the off-grid to grid-connected signal, the i-th slave energy storage inverter generates a grid-connected state signal of the i-th slave energy storage inverter according to the off-grid to grid-connected signal, and sends the grid-connected state signal to the master energy storage inverter.

[0080] Exemplarily, when the operating state of the first slave energy storage inverter is a grid-connected operating state and the state switching signal is an off-grid to grid-connected signal, the first slave energy storage inverter generates a grid-connected state signal of the first slave energy storage inverter according to the off-grid to grid-connected signal, and sends the grid-connected state signal to the master energy storage inverter.

[0081] Optionally, in one embodiment, S140 includes:

[0082] S141. When the state switching signal is a grid-connected-to-off-grid signal and the i-th state signal of the i-th slave energy storage inverter is an off-grid state signal, control the master energy storage inverter to send a grid-connected-to-off-grid signal to the i+1-th slave energy storage inverter according to the off-grid state signal.

[0083] Exemplarily, when the operating state of the first slave energy storage inverter is an off-grid operating state and the state switching signal is a grid-connected to off-grid signal, the first slave energy storage inverter generates an off-grid state signal of the first slave energy storage inverter according to the grid-connected to off-grid signal, and sends the off-grid state signal to the master energy storage inverter. The master energy storage inverter sends a grid-connected to off-grid signal to the second slave energy storage inverter according to the off-grid state signal.

[0084] or,

[0085] S142. When the state switching signal is an off-grid to grid-connected signal and the i-th state signal of the i-th slave energy storage inverter is a grid-connected state signal, control the master energy storage inverter to send an off-grid to grid-connected signal to the i+1-th slave energy storage inverter according to the grid-connected state signal.

[0086] Exemplarily, when the operating state of the first slave energy storage inverter is the grid-connected operating state and the state switching signal is an off-grid to grid-connected signal, the first slave energy storage inverter generates a grid-connected state signal of the first slave energy storage inverter according to the off-grid to grid-connected signal, and sends the grid-connected state signal to the master energy storage inverter. The master energy storage inverter sends an off-grid to grid-connected signal to the second slave energy storage inverter according to the grid-connected state signal.

[0087] Optionally, in one embodiment, after S130, the method further includes:

[0088] S150: Obtain output power at the load end.

[0089] Specifically, the output power is calculated by collecting the output current and output voltage of the load end of the energy storage converter.

[0090] S160. Determine whether to generate a state switching signal through the master energy storage converter according to the difference between the output power and the preset power threshold, and if so, send the state switching signal to the (i+1)th slave energy storage converter.

[0091] The preset power threshold can be preset according to the rated power value.

[0092] Specifically, after switching the operating mode of the i-th slave energy storage inverter, it is necessary to determine whether the output power meets the preset power threshold. If the output power after switching the operating mode of the i-th slave energy storage inverter meets the preset power threshold, there is no need to generate a state switching signal to adjust the operating mode of other slave energy storage inverters; if the output power after switching the operating mode of the i-th slave energy storage inverter meets the preset power threshold, it means that the system still has an overload risk or does not meet the operating requirements, then it is necessary to generate a state switching signal again and send the signal to the i+1-th slave energy storage inverter.

[0093] Exemplarily, after switching the operating mode of the first slave energy storage inverter, it is necessary to determine whether the output power meets the preset power threshold. If the output power after switching the operating mode of the first slave energy storage inverter meets the preset power threshold, there is no need to regenerate a state switching signal to adjust the operating modes of other slave energy storage inverters; if the output power after switching the operating mode of the first slave energy storage inverter does not meet the preset power threshold, it means that the system still has an overload risk or does not meet the operating requirements, then it is necessary to regenerate a state switching signal and send the signal to the second slave energy storage inverter.

[0094] Optionally, the preset power threshold includes a first preset power threshold and a second preset power threshold;

[0095] In one embodiment, S160 includes:

[0096] S161. When the output power is greater than or equal to a first preset power threshold, a grid-connected to off-grid signal is generated by the main energy storage converter.

[0097] The first preset power threshold is 80% of the rated power of the energy storage converter, and the second preset power threshold is 40% of the rated power of the energy storage converter.

[0098] Specifically, when the output power is greater than or equal to 80% of the rated power, a grid-connected to off-grid signal is generated by the master energy storage converter, and the grid-connected to off-grid signal is sent to the i+1th slave energy storage converter. Exemplarily, if the output power after switching the operating mode of the first slave energy storage converter is greater than or equal to 80% of the rated power, it means that the system still has an overload risk, and then it is necessary to generate a state switching signal again and send the signal to the second slave energy storage converter.

[0099] S162: When the output power is less than or equal to a second preset power threshold, a main energy storage converter is used to generate an off-grid to grid-connected signal.

[0100] The first preset power threshold is greater than the second preset power threshold.

[0101] Specifically, when the output power is less than or equal to 40% of the rated power, an off-grid-to-grid signal is generated by the main energy storage converter, and the off-grid-to-grid signal is sent to the (i+1)th slave energy storage converter.

[0102] For example, if the output power after switching the operating mode of the first slave energy storage inverter is less than or equal to 40% of the rated power, it means that the system does not meet the operating requirements, so it is necessary to regenerate a state switching signal and send the signal to the second slave energy storage inverter.

[0103] S163: When the output power is greater than the second preset power threshold and less than the first preset power threshold, control the main energy storage converter to stop generating a state switching signal.

[0104] Specifically, when the output power is greater than 40% of the rated power and less than 80% of the rated power, the main energy storage converter is controlled to stop generating the state switching signal.

[0105] Optionally, in one embodiment, S120 further includes:

[0106] S123: When the output current is greater than the second preset current threshold and less than the first preset current threshold, control the main energy storage converter to stop generating a state switching signal.

[0107] Specifically, when the output current is greater than 40% of the rated current and less than 80% of the rated current, the main energy storage converter is controlled to stop generating the state switching signal.

[0108] The technical solution provided in the embodiment of the present application further determines whether to adjust the operating mode of the slave energy storage inverter through the difference between the output power and the preset power threshold, thereby playing a further strengthening role, and automatically adjusting the number of energy storage inverters in the grid-connected mode / off-grid mode among multiple energy storage inverters according to changes in user load, thereby improving the service life of the energy storage inverter, the utilization efficiency of the energy storage inverter and the energy conversion capability, and improving the customer economic effect and the adaptability of the system.

[0109] Continue to see Figure 2 The parallel control system of the energy storage converter includes a grid end 210 and a load end 220, and n energy storage converters 230 connected in parallel between the grid end 210 and the load end 220; the n energy storage converters include 1 master energy storage converter and n-1 slave energy storage converters; n is a positive integer greater than or equal to 2.

[0110] The parallel control system of the energy storage converter also includes:

[0111] The acquisition module is used to acquire the output current of the load end of the energy storage converter. The specific acquisition process can refer to step S110 and step S150 in the above embodiment, which will not be described in detail here.

[0112] The master energy storage converter is used to generate a state switching signal according to the difference between the output current and the preset current threshold, and send the state switching signal to the i-th slave energy storage converter. For the specific process, refer to step S120 and step S160 in the above embodiment, wherein step S120 includes step S121, step S122 and step S123; step S160 includes step S161, step S162 and step S163; they will not be repeated here.

[0113] The i-th slave energy storage inverter is used to switch the operating mode of the i-th slave energy storage inverter or generate the i-th state signal according to the state switching signal and the operating state of the i-th slave energy storage inverter; i is a positive integer greater than or equal to 1 and less than n-1. For the specific process, refer to step S130 in the above embodiment. Step S130 includes step S131a, step S131b, S132a and step S132b.

[0114] The master energy storage converter is also used to send a state switching signal to the (i+1)th slave energy storage converter according to the i-th state signal. For the specific process, see step S140 in the above embodiment. Step S140 includes step S141 and step S142, which will not be repeated here.

[0115] Optionally, the preset current threshold includes a first preset current threshold and a second preset current threshold;

[0116] The main energy storage converter is also used to generate a grid-connected to off-grid signal when the output current is greater than or equal to a first preset current threshold, and send the grid-connected to off-grid signal to the i-th slave energy storage converter.

[0117] The main energy storage inverter is also used to generate an off-grid to grid-connected signal when the output current is less than or equal to a second preset current threshold, and send the off-grid to grid-connected signal to the i-th slave energy storage inverter; wherein the first preset current threshold is greater than the second preset current threshold.

[0118] The parallel control system provided in the embodiments of the present application can execute the parallel control method provided in any embodiment of the present application, and has the corresponding functional modules and beneficial effects of the execution method.

[0119] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this application can be executed in parallel, sequentially or in different orders, as long as the expected results of the technical solution of this application can be achieved, and this document is not limited here.

[0120] The above specific implementations do not constitute a limitation on the protection scope of this application. It should be understood by those skilled in the art 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 principles of this application should be included in the protection scope of this application.

Claims

1. A parallel control method for an energy storage converter, characterized in that: A parallel control system for an energy storage converter, the parallel control system for the energy storage converter comprising a grid end and a load end, and n energy storage converters connected in parallel between the grid end and the load end, the n energy storage converters comprising a master energy storage converter and n-1 slave energy storage converters; n is a positive integer greater than or equal to 2; The parallel control method of the energy storage converter comprises: Obtaining the output current of the load end of the energy storage converter; Generate a state switching signal through the master energy storage converter according to the difference between the output current and a preset current threshold, and send the state switching signal to the i-th slave energy storage converter; By means of the i-th slave energy storage converter, according to the state switching signal and the operating state of the i-th slave energy storage converter, the operating mode of the i-th slave energy storage converter is switched or the i-th state signal is generated; i is a positive integer greater than or equal to 1 and less than n-1; The state switching signal is sent to the (i+1)th slave energy storage converter via the master energy storage converter according to the i-th state signal.

2. The parallel control method according to claim 1, characterized in that: The preset current threshold comprises a first preset current threshold and a second preset current threshold; The generating a state switching signal by the master energy storage converter according to the difference between the output current and the preset current threshold, and sending the state switching signal to the i-th slave energy storage converter comprises: When the output current is greater than or equal to the first preset current threshold, a grid-connected to off-grid signal is generated by the master energy storage converter, and the grid-connected to off-grid signal is sent to the i-th slave energy storage converter; When the output current is less than or equal to the second preset current threshold, an off-grid to grid-connected signal is generated by the master energy storage inverter, and the off-grid to grid-connected signal is sent to the i-th slave energy storage inverter; wherein the first preset current threshold is greater than the second preset current threshold.

3. The parallel control method according to claim 1, characterized in that: The step of switching the operation mode of the i-th slave energy storage converter or generating the i-th state signal according to the state switching signal and the operation state of the i-th slave energy storage converter through the i-th slave energy storage converter comprises: When the operation state of the i-th slave energy storage converter is the grid-connected operation state, and the state switching signal is a grid-connected to off-grid signal, the i-th slave energy storage converter is controlled to switch to the off-grid operation mode according to the grid-connected to off-grid signal; When the operation state of the i-th slave energy storage inverter is an off-grid operation state and the state switching signal is an off-grid to grid-connected signal, the i-th slave energy storage inverter is controlled to switch to a grid-connected operation mode according to the off-grid to grid-connected signal.

4. The parallel control method according to claim 1, characterized in that: The operation state is said to switch the operation mode of the i-th slave energy storage converter or generate the i-th state signal according to the state switching signal and the operation state of the i-th slave energy storage converter through the i-th slave energy storage converter, and also includes: When the operation state of the i-th slave energy storage converter is an off-grid operation state, and the state switching signal is a grid-connected to off-grid signal, an off-grid state signal of the i-th slave energy storage converter is generated by the i-th slave energy storage converter according to the grid-connected to off-grid signal, and the off-grid state signal is sent to the master energy storage converter; the i-th state signal includes the off-grid state signal of the i-th slave energy storage converter; Alternatively, when the operating state of the i-th slave energy storage inverter is a grid-connected operating state, and the state switching signal is an off-grid to grid-connected signal, the i-th slave energy storage inverter generates a grid-connected state signal of the i-th slave energy storage inverter according to the off-grid to grid-connected signal, and sends the grid-connected state signal to the master energy storage inverter; the i-th state signal also includes the grid-connected state signal of the i-th slave energy storage inverter.

5. The parallel control method according to claim 4, wherein sending the state switching signal to the (i+1)th slave energy storage converter according to the i-th state signal through the master energy storage converter comprises: When the state switching signal is a grid-connected-to-off-grid signal and the i-th state signal of the i-th slave energy storage converter is an off-grid state signal, controlling the master energy storage converter to send the grid-connected-to-off-grid signal to the i+1-th slave energy storage converter according to the off-grid state signal; Alternatively, when the state switching signal is an off-grid to grid-connected signal and the i-th state signal of the i-th slave energy storage inverter is a grid-connected state signal, the master energy storage inverter is controlled to send the off-grid to grid-connected signal to the i+1-th slave energy storage inverter according to the grid-connected state signal.

6. The parallel control method according to claim 1, characterized in that: After switching the operation mode of the i-th slave energy storage converter according to the state switching signal and the operation state of the i-th slave energy storage converter through the i-th slave energy storage converter, the method further includes: Obtaining the output power of the load end; Through the master energy storage converter, it is determined whether to generate a state switching signal according to the difference between the output power and the preset power threshold, and if so, the state switching signal is sent to the (i+1)th slave energy storage converter.

7. The parallel control method according to claim 6, characterized in that: The preset power threshold includes a first preset power threshold and a second preset power threshold; The determining, by the main energy storage converter, whether to generate a state switching signal according to a difference between the output power and a preset power threshold comprises: When the output power is greater than or equal to the first preset power threshold, a grid-connected to off-grid signal is generated by the main energy storage converter; When the output power is less than or equal to the second preset power threshold, an off-grid to grid-connected signal is generated by the main energy storage converter; wherein the first preset power threshold is greater than the second preset power threshold; When the output power is greater than the second preset power threshold and less than the first preset power threshold, the main energy storage converter is controlled to stop generating a state switching signal.

8. The parallel control method according to claim 2, characterized in that: The generating a state switching signal according to the difference between the output current and the preset current threshold by the master energy storage converter, and sending the state switching signal to the i-th slave energy storage converter further comprises: When the output current is greater than the second preset current threshold and less than the first preset current threshold, the main energy storage converter is controlled to stop generating a state switching signal.

9. A parallel control system for an energy storage converter, characterized in that: The parallel control system of the energy storage converter includes a grid end and a load end, and n energy storage converters connected in parallel between the grid end and the load end; the n energy storage converters include 1 master energy storage converter and n-1 slave energy storage converters; n is a positive integer greater than or equal to 2; The parallel control system of the energy storage converter also includes: An acquisition module, used for acquiring the output current of the load end of the energy storage converter; The master energy storage converter is used to generate a state switching signal according to the difference between the output current and the preset current threshold, and send the state switching signal to the i-th slave energy storage converter; The i-th slave energy storage converter is used to switch the operation mode of the i-th slave energy storage converter or generate an i-th state signal according to the state switching signal and the operation state of the i-th slave energy storage converter; i is a positive integer greater than or equal to 1 and less than n-1; The master energy storage converter is further configured to send the state switching signal to the (i+1)th slave energy storage converter according to the i-th state signal.

10. The parallel control system according to claim 9, characterized in that: The preset current threshold comprises a first preset current threshold and a second preset current threshold; The master energy storage converter is further configured to generate a grid-connected to off-grid switching signal when the output current is greater than or equal to the first preset current threshold, and send the grid-connected to off-grid switching signal to the i-th slave energy storage converter; The master energy storage inverter is also used to generate an off-grid to grid-connected signal when the output current is less than or equal to the second preset current threshold, and send the off-grid to grid-connected signal to the i-th slave energy storage inverter; wherein the first preset current threshold is greater than the second preset current threshold.

Images