Converter system control method and apparatus, and power system

Abstract

The present application relates to the technical field of power control, and in particular relates to a converter system control method and apparatus, and a power system. The converter system comprises a power grid access end, and multiple energy storage converter devices connected to the power grid access end and configured in parallel, each of the energy storage converter devices comprising a battery cluster. The converter system control method comprises: controlling the battery cluster of at least one of the energy storage converter devices to be in a state of alternating operation between charging and discharging; and controlling the remaining energy storage converter devices to be in a standby state. By means of controlling the battery cluster of at least one energy storage converter device to be in the state of alternating operation between charging and discharging, the battery cluster is placed in a charging-discharging cycling state, thereby maintaining battery health of the battery cluster at a relatively high level, keeping the performance of the battery cluster stable, and reducing the likelihood of failures due to power feeding of the battery cluster, and the replacement frequency.

Description

Control methods and devices for converter systems, power systems

[0001] This application claims priority to Chinese Patent Application No. 202410692468.5, filed on May 30, 2024, entitled "Control Method and Apparatus for Converter System, Power System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of power control technology, and in particular to a control method and apparatus for a converter system and a power system. Background Technology

[0003] In a power system, when the system is disturbed, power oscillations occur. At this time, the power parameters in the system (e.g., voltage at various points and current in each loop) will change, deviating from preset values.

[0004] Currently, with the rapid development of converter technology, its application in power systems to mitigate power oscillations is widely used. In related technologies, to quickly alleviate power oscillations, a single energy storage converter is typically kept in a zero-power operation state for an extended period. However, this leads to power depletion of the battery clusters in the energy storage converter, reducing their lifespan.

[0005] Summary of the Invention

[0006] Therefore, it is necessary to provide a control method and device for a converter system that improves the lifespan of battery clusters, as well as a power system.

[0007] On one hand, this application provides a control method for a converter system, the converter system including a grid connection terminal and multiple energy storage converter devices connected in parallel to the grid connection terminal, each of the energy storage converter devices including a battery cluster, and the control method for the converter system including:

[0008] Controlling at least one of the battery clusters of the energy storage converter to be in a state of alternating charging and discharging;

[0009] The remaining energy storage converters are kept in standby mode.

[0010] In one embodiment, each of the energy storage converters includes a switching circuit connected between the battery cluster and the grid access terminal, the switching circuit being used to control the battery cluster to be in a state of alternating charging and discharging;

[0011] The control of at least one of the battery clusters of the energy storage converter to operate in an alternating charging and discharging state includes:

[0012] The switching circuit is controlled to operate in the first working mode for a first preset duration so that the battery cluster of at least one of the energy storage converters is in either a charging or discharging state.

[0013] The switching circuit is switched to a different operating mode, and the switching circuit is controlled to run for a second preset duration in the second operating mode, so that the battery cluster of the at least one energy storage converter is in another state of charging or discharging.

[0014] In one embodiment, the switching circuit operates at the same power in the first operating mode as in the second operating mode.

[0015] In one embodiment, controlling at least one of the battery clusters of the energy storage converter to operate in an alternating charging and discharging state includes:

[0016] Determine the rated power of the switching circuit;

[0017] Based on the rated power, the operating power of the switching circuit in the first operating mode and the second operating mode is set.

[0018] In one embodiment, the first preset power and the second preset power are respectively one percent to five percent of the rated power.

[0019] In one embodiment, the first preset duration is equal to the second preset duration.

[0020] or,

[0021] The first preset duration is the duration during which the battery cluster is in a charging state, and the second preset duration is the duration during which the battery cluster is in a discharging state. The first preset duration is longer than the second preset duration.

[0022] In one embodiment, the switching circuit includes a transformer circuit, the first operating mode includes a boost mode, and the second operating mode includes a buck mode.

[0023] In one embodiment, controlling the remaining energy storage converter to be in standby mode includes:

[0024] The switching circuit of the remaining energy storage converter is disconnected.

[0025] On one hand, a control device for a converter system is provided, the converter system including a grid connection terminal and a plurality of energy storage converter devices connected in parallel to the grid connection terminal, each of the energy storage converter devices including a battery cluster, and the control device for the converter system including:

[0026] The first control module is used to control the battery cluster of at least one of the energy storage converters to be in a state of alternating charging and discharging;

[0027] The second control module is used to control the remaining energy storage converters to be in standby mode.

[0028] On the one hand, a power system is provided, the power system comprising:

[0029] Grid connection end;

[0030] Multiple energy storage converters are connected in parallel to the grid access terminal, and each energy storage converter includes a battery cluster;

[0031] A control unit is connected to the plurality of energy storage converter devices, and the control unit controls the plurality of energy storage converter devices according to the control method of the converter system described in the first aspect or any embodiment thereof.

[0032] The control method and device of the above-mentioned converter system and power system control the battery cluster of at least one energy storage converter to be in a state of alternating charging and discharging, thereby keeping the battery cluster in a charge-discharge cycle state, thus maintaining the battery health of the battery cluster at a high level, keeping the performance of the battery cluster stable, and reducing the probability and frequency of failures caused by battery cluster power depletion. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 is a schematic diagram of a power system provided in an embodiment;

[0035] Figure 2 is a schematic diagram of a control method for a converter system provided in an embodiment;

[0036] Figure 3 is a schematic diagram of a power system provided in another embodiment;

[0037] Figure 4 is a schematic diagram of the control device of a converter system provided in one embodiment.

[0038] Explanation of reference numerals in the attached diagram: Power system - 100; Grid access terminal - 110; Energy storage converter - 120; First-stage converter unit - 120A; Second-stage converter unit - 120B; Battery cluster - 121; Switching circuit - 122; Bidirectional DCAC circuit - 1221; DC-DC circuit - 1222; Photovoltaic module - 123.

[0039] To better describe and illustrate embodiments and / or examples of the inventions disclosed herein, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed inventions, the currently described embodiments and / or examples, or the best mode of these inventions as currently understood. Detailed Implementation

[0040] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0042] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0043] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0044] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0045] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0046] In one embodiment, please refer to Figure 1, which illustrates an exemplary power system 100. The power system 100 includes a grid connection terminal 110, multiple energy storage converters 120, and a control unit.

[0047] The grid access terminal 110 is used for grid connection. Multiple energy storage converters 120 are connected in parallel and connected to the grid access terminal 110. When power oscillations occur in the grid, the power oscillations can be mitigated by charging and discharging the battery clusters 121 in the multiple energy storage converters 120.

[0048] For example, each energy storage converter 120 may include a first-stage converter unit 120A and a second-stage converter unit 120B connected in series, thereby forming a multi-stage converter system. The first-stage converter unit 120A may include a battery cluster 121 and a DC-DC circuit 1222. The second-stage converter unit 120B may include a connected AC circuit breaker K and a bidirectional DC-AC circuit 1221. In addition, the second-stage converter unit 120B may also include a filter capacitor C and a filter inductor L. The filter inductor L may be connected between the AC circuit breaker K and the bidirectional DC-AC circuit 1221. One end of the filter capacitor C may be connected to the line between the filter inductor L and the AC circuit breaker K, and the other end may be connected to the ground terminal.

[0049] In addition, the power system 100 may include a portion of energy storage converter 120 comprising battery clusters 121, and another portion of energy storage converter 120 comprising parallel battery clusters 121 and a DC coupling system. The DC coupling system may include photovoltaic modules 123 such as solar panels.

[0050] In related technologies, it is common practice to set one energy storage converter to operate at zero power, while the other n-1 energy storage converters are all in standby mode. This way, when power grid fluctuations occur, multiple energy storage converters can promptly charge and discharge each battery cluster. Setting one energy storage converter to operate at zero power can be achieved by controlling the on / off states of its switches, thereby limiting the current to that specific converter and thus maintaining its zero-power operation. Setting the other n-1 energy storage converters to standby mode can be achieved by simultaneously opening the AC circuit breakers of only the other n-1 converters while disconnecting their DC-DC (DCDC) and / or bidirectional DC-AC (DCAC) circuits, thus placing the other n-1 energy storage converters in standby mode.

[0051] The inventors discovered that controlling the energy storage converter 120 to operate at 0 power has poor operational accuracy. Furthermore, prolonged operation of the energy storage converter 120 at 0 power can lead to power depletion of the corresponding battery cluster 121, reducing its capacity and negatively impacting the power system 100. In this embodiment, a control unit is connected to multiple energy storage converters 120. The control unit controls these multiple energy storage converters 120 according to a control method for a converter system formed by any of the following multiple embodiments. By controlling the battery cluster 121 of at least one energy storage converter 120 to operate in an alternating charging and discharging state, the battery cluster 121 is kept in a charge-discharge cycle, thereby maintaining the battery health of the battery cluster 121 at a high level, ensuring stable performance, and reducing the probability and frequency of failures and replacements caused by power depletion of the battery cluster 121.

[0052] Based on the same inventive concept, referring to Figure 2, in one embodiment, a control method for a converter system is provided. The control method for the converter system includes the following steps:

[0053] Step S2: Control the battery cluster 121 of at least one energy storage converter 120 to be in a state of alternating charging and discharging.

[0054] Step S4: Control the remaining energy storage converter 120 to be in standby mode.

[0055] In step S2, among the multiple energy storage converters 120, the method of step S2 can be performed on one energy storage converter 120 or multiple energy storage converters 120.

[0056] Each energy storage converter 120 includes a battery cluster 121. Each battery cluster 121 may consist of multiple individual battery cells. During normal operation, the battery cluster 121 may have both a charging state and a discharging state. In one example, the state of the battery cluster 121 can be switched to control it to alternate between charging and discharging. In another example, the energy storage converter 120 further includes a switching circuit 122 connected between the battery cluster 121 and the grid connection 110. In this case, switching the switching circuit 122 can control the battery cluster 121 to alternate between charging and discharging.

[0057] In step S4, in one example, the switch between part of the remaining energy storage converter 120 and the grid connection terminal 110 can be turned on (e.g., turning on the AC circuit breaker K), while the switch between part of the remaining energy storage converter 120 and the grid connection terminal 110 can be turned off (e.g., turning off the DC-DC circuit 1222), to control the remaining energy storage converter 120 to be in a standby state. In another example, the remaining energy storage converter 120 can be controlled to be in a standby state by stopping the operation of the battery cluster 121.

[0058] In this embodiment, by controlling the battery cluster 121 of at least one energy storage converter 120 to be in a state of alternating charging and discharging, the battery cluster 121 is in a charge-discharge cycle state, thereby maintaining the battery health of the battery cluster 121 at a high level, keeping the performance of the battery cluster 121 stable, and reducing the probability and frequency of failures caused by the battery cluster 121 being depleted.

[0059] In this embodiment, while controlling at least one energy storage converter 120's battery cluster 121 to operate in alternating charging and discharging mode, the remaining energy storage converters 120 are also controlled to be in standby mode. In the event of power grid oscillations, multiple energy storage converters 120 can promptly charge and discharge each battery cluster 121. At this time, the battery cluster 121 can absorb excess power from the power system 100, or it can apply power to the power system 100, thereby eliminating power oscillations.

[0060] In one embodiment, each energy storage converter 120 includes a switching circuit 122 connected between the battery cluster 121 and the grid connection 110. The switching circuit 122 is used to control the battery cluster 121 to operate in an alternating charging and discharging state. At this time, step S2 includes:

[0061] Step S22: The control switching circuit 122 operates in the first working mode for a first preset time so that the battery cluster 121 of at least one energy storage converter 120 is in either a charging or discharging state.

[0062] Step S24: Switch the operating mode of the switching circuit 122 and control the switching circuit 122 to run for a second preset time in the second operating mode so that the battery cluster 121 of at least one energy storage converter 120 is in another state of charging or discharging.

[0063] In steps S22 and S24, as an example, the switching circuit 122 may include a transformer circuit. In this case, the first operating mode includes a boost mode, and the second operating mode includes a buck mode.

[0064] As mentioned above, the energy storage converter 120 may include a bidirectional DCAC circuit 1221 and a DC-DC converter 1222. The following description uses the switching circuit 122 as a DC-DC converter 1222 as an example to illustrate the method of this embodiment. After the bidirectional DCAC circuit 1221 is turned on, firstly, the DC-DC converter 1222 can be controlled to be in boost mode, increasing the voltage of the grid connection terminal 110. When the voltage of the grid connection terminal 110 is higher than the voltage of the battery cluster 121, the battery cluster 121 is in a charging state. After the battery cluster 121 is in a charging state and maintains this state for a first preset time, the DC-DC converter 1222 is controlled to be in buck mode, so that when the voltage of the battery cluster 121 is higher than the voltage of the grid connection terminal 110, the battery cluster 121 is in a discharging state. Afterwards, after the battery cluster 121 is in a discharging state and maintains this state for a second preset time, the DC-DC converter 1222 can be controlled to be in boost mode, and the above steps are repeated.

[0065] It is understood that the DC-DC circuit 1222 includes multiple switches and transformers, and the operating mode of the DC-DC circuit 1222 can be switched by controlling the on / off state of each switch.

[0066] In this embodiment, the specific form of the switching circuit 122 is not limited. That is, the switching circuit 122 can be a DC-DC circuit 1222, a bidirectional DC-AC circuit 1221, or a circuit formed by combining the DC-DC circuit 1222 and the bidirectional DC-AC circuit 1221.

[0067] Furthermore, referring to Figure 3, each energy storage converter 120 may include multiple battery clusters 121 connected in parallel. In the control method of the converter system, all the battery clusters 121 connected in parallel in at least one energy storage converter 120 can be controlled to alternate between charging and discharging, or at least one battery cluster 121 in at least one energy storage converter 120 can be controlled to alternate between charging and discharging. Of course, in this case, each energy storage converter 120 may also include a DC-DC circuit 1222 corresponding to each battery cluster 121 therein.

[0068] In this embodiment, by switching the working mode of the switching circuit 122, it is easier to control the battery cluster 121 to be in an alternating charging or discharging state, thus reducing the difficulty of control.

[0069] This embodiment does not limit the specific values ​​of the first preset duration and the second preset duration. As an example, the first preset duration can be between 5 and 15 minutes, and the second preset duration can also be between 5 and 15 minutes. The first and second preset durations can be the same, which can balance the charging and discharging time of the battery cluster 121, thereby further improving the health of the battery cluster 121. For example, the first and second preset durations can both be 10 minutes. The first and second preset durations can also be different. For example, the first preset duration is the duration of the battery cluster 121 in the charging state, and the second preset duration is the duration of the battery cluster 121 in the discharging state, with the first preset duration being longer than the second preset duration. In this case, the granularity of the duration of the battery cluster 121 in the discharging state can be as small as possible.

[0070] In one embodiment, the operating power of the switching circuit 122 is the same in the first operating mode and the second operating mode. As an example, the operating power of the switching circuit 122 can be controlled by controlling the on / off state of each switch in the switching circuit 122.

[0071] In this embodiment, the operating power of the switching circuit 122 in the first working mode and the second working mode is the same, so as to balance the charging and discharging power of the battery cluster 121 and improve the health of the battery cluster 121.

[0072] Accordingly, step S2 includes:

[0073] Step S26: Determine the rated power of switching circuit 122.

[0074] Step S28: Based on the rated power, set the operating power of the switching circuit 122 in the first operating mode and the second operating mode.

[0075] In steps S26 and S28, for example, the operating power of the switching circuit 122 in the first operating mode and the second operating mode can be set to one percent to five percent of the rated power of the switching circuit 122. For example, when the switching circuit 122 is a DC-DC circuit 1222, the rated power of the DC-DC circuit 1222 is usually set to 200kW. Setting the operating power of the switching circuit 122 in the first operating mode and the second operating mode to one percent of the rated power means that the operating power of the switching circuit 122 in the first operating mode and the second operating mode is 5kW.

[0076] In this embodiment, by setting the operating power of the switching circuit 122 in the first working mode and the second working mode, not only can the operating accuracy be guaranteed, but also the operating power value is small and will not increase too much loss.

[0077] It should be understood that although the steps in the flowchart of Figure 2 are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some of the steps in Figure 2 may include multiple steps or multiple stages, which are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps.

[0078] Based on the same inventive concept, please refer to Figure 4. In one embodiment, a control device for a converter system is provided. The control device for the converter system includes: a first control module and a second control module.

[0079] The first control module is used to control the battery cluster 121 of at least one energy storage converter 120 to be in a state of alternating charging and discharging.

[0080] The second control module is used to keep the remaining energy storage converter 120 in standby mode.

[0081] In one embodiment, the first control module is further configured to control the switching circuit 122 to operate in a first operating mode for a first preset duration, so that the battery cluster 121 of at least one energy storage converter 120 is in either a charging or discharging state. The first control module is further configured to switch the operating mode of the switching circuit 122 and control the switching circuit 122 to operate in a second operating mode for a second preset duration, so that the battery cluster 121 of at least one energy storage converter 120 is in the other state of charging or discharging.

[0082] In one embodiment, the first control module is further configured to determine the rated power of the switching circuit 122. The first control module is also configured to set the operating power of the switching circuit 122 in a first operating mode and a second operating mode based on the rated power.

[0083] The control device of the above-mentioned converter system controls the battery cluster 121 of at least one energy storage converter 120 to be in a state of alternating charging and discharging, thereby keeping the battery cluster 121 in a charge-discharge cycle state, thus maintaining the battery health of the battery cluster 121 at a high level, keeping the performance of the battery cluster 121 stable, reducing the probability and frequency of failures caused by the battery cluster 121 being depleted, and reducing the frequency of replacement.

[0084] Specific limitations regarding the control device of the converter system can be found in the limitations on the control method of the converter system above, and will not be repeated here. Each module in the control device of the aforementioned converter system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware or independently of the processor in the computer device, or stored in software in the memory of the computer device, so that the processor can call and execute the corresponding operations of each module.

[0085] It is understood that the power system 100, switching circuit 122 and battery cluster 121 described above can also take other forms, and are not limited to the forms already mentioned in the above embodiments, as long as they can achieve the functions of the power system 100, switching circuit 122 and battery cluster 121.

[0086] In the description of this specification, references to terms such as "some embodiments," "other embodiments," 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 descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0087] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A control method of a power conversion system, characterized by, The converter system includes a grid connection terminal and multiple energy storage converter devices connected in parallel to the grid connection terminal. Each energy storage converter device includes a battery cluster. The control method of the converter system includes: Controlling at least one of the battery clusters of the energy storage converter to be in a state of alternating charging and discharging; The remaining energy storage converters are kept in standby mode.

2. The control method of a current conversion system according to claim 1, characterized by, Each of the energy storage converters includes a switching circuit connected between the battery cluster and the grid connection terminal, the switching circuit being used to control the battery cluster to operate in an alternating charging and discharging state; The control of at least one of the battery clusters of the energy storage converter to operate in an alternating charging and discharging state includes: The switching circuit is controlled to operate in the first working mode for a first preset duration so that the battery cluster of at least one of the energy storage converters is in either a charging or discharging state. The switching circuit is switched to a different operating mode, and the switching circuit is controlled to run for a second preset duration in the second operating mode, so that the battery cluster of the at least one energy storage converter is in another state of charging or discharging.

3. The control method of a current conversion system according to claim 2, characterized by, The switching circuit operates at the same power in the first operating mode as it does in the second operating mode.

4. The control method for the converter system according to claim 3, characterized in that, The control of at least one of the battery clusters of the energy storage converter to operate in an alternating charging and discharging state includes: Determine the rated power of the switching circuit; Based on the rated power, the operating power of the switching circuit in the first operating mode and the second operating mode is set.

5. The control method for the converter system according to claim 4, characterized in that, The first preset power and the second preset power are respectively one percent to five percent of the rated power.

6. The control method for the converter system according to claim 2, characterized in that, The first preset duration is equal to the second preset duration. or, The first preset duration is the duration during which the battery cluster is in a charging state, and the second preset duration is the duration during which the battery cluster is in a discharging state. The first preset duration is longer than the second preset duration.

7. The control method for the converter system according to claim 2, characterized in that, The switching circuit includes a transformer circuit, the first operating mode includes a boost mode, and the second operating mode includes a buck mode.

8. The control method for the converter system according to claim 2, characterized in that, The control of the remaining energy storage converters to be in standby mode includes: The switching circuit of the remaining energy storage converter is disconnected.

9. A control device for a converter system, characterized in that, The converter system includes a grid connection terminal and multiple energy storage converter devices connected in parallel to the grid connection terminal. Each energy storage converter device includes a battery cluster. The control device of the converter system includes: The first control module is used to control the battery cluster of at least one of the energy storage converters to be in a state of alternating charging and discharging; The second control module is used to control the remaining energy storage converters to be in standby mode.

10. An electric power system, characterized in that, The power system includes: Grid connection end; Multiple energy storage converters are connected in parallel to the grid access terminal, and each energy storage converter includes a battery cluster; A control unit is connected to the plurality of energy storage converter devices, and the control unit controls the plurality of energy storage converter devices according to the control method of the converter system according to any one of claims 1-8.

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