Converter control method, power conversion device and energy storage power supply system

Abstract

The invention provides a control method of a converter, a power conversion device and an energy storage power supply system. Wherein the input end of the converter is used for connecting a first power supply, the output end of the converter and the output end of a second power supply are connected to an AC bus in parallel, the AC bus is used for connecting a load, and the power supply priority of the first power supply is higher than that of the second power supply. The control method comprises the steps of firstly obtaining a load current value and a preset adjustment coefficient, then calculating a current adjustment value according to the load current value and the preset adjustment coefficient, and then calculating a reference voltage value of the converter according to a reference output current value of the converter, the current adjustment value, an actual output current value of the converter and an alternating current bus voltage value, and finally generating an output control signal according to the reference voltage value and the input voltage value of the converter to control the output of the converter. According to the control method, the situation that the current of the converter flows back to the second power supply due to sudden change of the load can be avoided.

Description

Technical Field

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

[0002] When the energy storage power supply is connected in parallel with the generator to carry the load, if the energy storage power supply has sufficient power, the energy storage power supply is usually allowed to supply power to the load first, the energy storage power supply outputs at full power, and the generator then makes up for the power supply difference. In order to adapt to the generators on the market, the converter (Power Conversion System, PCS) of the energy storage power supply usually adopts a current source control method. However, the current current source control method may cause the current of the PCS to be fed back to the generator when the load suddenly changes (such as complete unloading), causing the generator to be damaged or abnormally started. That is, when there are two power supplies in parallel to supply power to the load at the same time, the power supply priorities of different power supplies are different. When a sudden load change occurs, it is easy for a power supply with a high power supply priority to charge a power supply with a low power supply priority, causing damage to the power supply with a low power supply priority. Summary of the invention

[0003] In view of this, the present application provides a control method of an inverter, a power conversion device and an energy storage power supply system, which can avoid the current of a power supply with a higher power supply priority from being backflowed to a power supply with a lower power supply priority due to a sudden load change when two power supplies are connected in parallel, causing damage to the power supply with a lower power supply priority or abnormal shutdown.

[0004] The first aspect of the present application provides a control method for an inverter, wherein the input end of the inverter is used to connect to a first power supply, and the output end of the inverter is used to be connected to an AC bus in parallel with the output end of a second power supply; the AC bus is used to connect a load; the power supply priority of the first power supply is higher than the power supply priority of the second power supply; the control method includes: obtaining a load current value, and a preset adjustment coefficient for adjusting the output power of the inverter; calculating a current adjustment value according to the load current value and the preset adjustment coefficient; calculating a reference voltage value of the inverter according to a reference output current value of the inverter, the current adjustment value, the actual output current value of the inverter and the AC bus voltage value; generating an output control signal according to the reference voltage value and the input voltage value of the inverter, and the output control signal is used to control the output of the inverter.

[0005] In the control method of the present application, by obtaining the load current value and the preset adjustment coefficient, the current adjustment value is calculated according to the load current value and the preset adjustment coefficient, and then the reference voltage value of the converter is calculated according to the reference output current value of the converter, the current adjustment value, the actual output current value of the converter and the AC bus voltage value, and finally the output control signal is generated according to the reference voltage value and the input voltage value of the converter to control the output of the converter. Since the load current value can characterize the actual power of the load, when the load suddenly changes, the load current value will change with the sudden change of the load, so that the control process of the converter can respond to the sudden change of the load in time, and since the preset adjustment coefficient can be used to adjust the output power of the converter, the output of the converter can be adjusted to adapt to the load after the sudden change. Therefore, through the control method of the present application, when two power supplies are connected in parallel with load, it is possible to avoid the current of the power supply with a high power supply priority being fed back to the power supply with a low power supply priority due to a sudden change of the load, causing the power supply with a low power supply priority to be damaged or abnormally shut down.

[0006] In one embodiment, the control method further includes: obtaining a preset adjustment coefficient according to a power supply parameter of the first power supply.

[0007] In one embodiment, the power parameter of the first power source includes an actual state of charge of the first power source, and the magnitude of the preset adjustment coefficient is positively correlated with the magnitude of the actual state of charge of the first power source.

[0008] In one embodiment, a preset adjustment coefficient is obtained according to a power supply parameter of a first power supply, including: when an actual state of charge of the first power supply is greater than a first preset threshold value, determining that the preset adjustment coefficient is equal to a first preset adjustment value; when the actual state of charge of the first power supply is between the first preset threshold value and the second preset threshold value, determining that the preset adjustment coefficient is equal to the second preset adjustment value; when the actual state of charge of the first power supply is less than the second preset threshold value, determining that the preset adjustment coefficient is equal to a third preset adjustment value; wherein, the first preset threshold value is greater than the second preset threshold value, and the first preset adjustment value, the second preset adjustment value and the third preset adjustment value become smaller in sequence.

[0009] In one embodiment, a reference voltage value of the converter is calculated based on a reference output current value of the converter, a current adjustment value, an actual output current value of the converter, and an AC bus voltage value, including: calculating a target output current value based on the reference output current value and the current adjustment value; obtaining an initial voltage value after performing a deviation adjustment on a difference between the target output current value and the actual output current value of the converter; and obtaining a reference voltage value of the converter based on the initial voltage value and the AC bus voltage value.

[0010] In one embodiment, the control method also includes: obtaining an input voltage value and an input voltage target value of the converter; performing deviation adjustment on the difference between the input voltage value and the input voltage target value of the converter to obtain a reference current amplitude; and calculating a reference output current value of the converter based on the reference current amplitude and the output current phase.

[0011] In one embodiment, the control method further includes: when a discharge instruction is received, controlling the second power supply to start; after the second power supply is started, controlling the converter to connect to the grid and operate.

[0012] The second aspect of the present application provides a power conversion device, which includes an inverter and a controller. The input end of the inverter is used to connect to a first power supply, and the output end of the inverter is used to be connected to an AC bus in parallel with the output end of a second power supply; the AC bus is used to connect a load; the power supply priority of the first power supply is higher than the power supply priority of the second power supply; the controller is used to execute the control method of the inverter described in the first aspect or any one of the embodiments of the first aspect.

[0013] The third aspect of the present application provides an energy storage power supply system, which includes a first power supply and a power conversion device; the power conversion device includes an inverter and a controller, the input end of the inverter is used to connect to the first power supply, and the output end of the inverter is used to be connected to an AC bus in parallel with the output end of the second power supply; the AC bus is used to connect a load; the power supply priority of the first power supply is higher than the power supply priority of the second power supply; the controller is used to execute the control method of the inverter described in the first aspect or any one of the embodiments of the first aspect.

[0014] In one embodiment, the first power source is an energy storage power source; and the second power source is a generator.

[0015] The fourth aspect of the present application provides an electronic device, including a processor and a memory, the memory being used to store programs, instructions or codes, and the processor being used to execute the programs, instructions or codes in the memory to complete the control method of the converter described in the first aspect or any one of the embodiments of the first aspect.

[0016] In a fifth aspect, the present application provides a control device for a converter, comprising an acquisition module, a first calculation module, a second calculation module and a generation module. The acquisition module is used to acquire a load current value and a preset adjustment coefficient for adjusting the output power of the converter. The first calculation module is used to calculate a current adjustment value according to the load current value and the preset adjustment coefficient. The second calculation module is used to calculate a reference voltage value of the converter according to a reference output current value of the converter, a current adjustment value, an actual output current value of the converter and an AC bus voltage value. The generation module is used to generate an output control signal according to the reference voltage value and the input voltage value of the converter, and the output control signal is used to control the output of the converter.

[0017] A sixth aspect of the present application provides a computer-readable storage medium storing a computer program, which is loaded by a processor to execute the control method of the converter described in the first aspect or any one of the embodiments of the first aspect.

[0018] In addition, the technical effects brought about by any embodiment of the second to sixth aspects can refer to the technical effects brought about by different embodiments of the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of an application scenario of the converter control method provided in an embodiment of the present application.

[0020] Figure 2 It is a flow chart of a control method of a converter provided in an embodiment of the present application.

[0021] Figure 3 This is another flow chart of the converter control method provided in an embodiment of the present application.

[0022] Figure 4 yes Figure 2 A detailed flowchart of step S13 in FIG.

[0023] Figure 5 This is another flow chart of the converter control method provided in an embodiment of the present application.

[0024] Figure 6 This is another flow chart of the converter control method provided in an embodiment of the present application.

[0025] Figure 7 It is a control block diagram of the converter control method provided in an embodiment of the present application.

[0026] Figure 8 It is a schematic diagram of an electronic device provided in an embodiment of the present application.

[0027] Fig. 9 It is a schematic diagram of a control device for a converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] It should be noted that the terms "first", "second" and "third" in the specification, claims and drawings of the present application are used to distinguish similar objects rather than to describe a specific order or sequence.

[0029] It should also be noted that the method disclosed in the embodiments of the present application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchangeable with each other, and some of the steps can also be deleted.

[0030] Some embodiments will be described below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0031] When the energy storage power supply is connected in parallel with the generator, if the energy storage power supply is sufficient, the energy storage power supply is usually allowed to supply power to the load first, the energy storage power supply outputs at full power, and the generator then makes up for the power supply difference. At this time, the converter (Power Conversion System, PCS) of the energy storage power supply can adopt voltage source control or current source control. When the energy storage power supply adopts voltage source control, inertia and damping need to be introduced to make the PCS have mechanical characteristics similar to those of the generator, so that during the startup process, the PCS and the generator can share the impact current and improve the stability of the microgrid. However, in the face of different generators on the market, the PCS needs to adjust the voltage source control method accordingly to adapt to different inertia and damping. Such a control method is complex, not robust, and difficult to debug. In order to adapt to the generators on the market, the converter (Power Conversion System, PCS) in the energy storage power supply usually adopts current source control. The current source control method allows its output to track changes in load disturbances. However, the current current source control method is difficult to respond quickly when the load suddenly changes (such as complete unloading), which will cause the current output by the PCS to be fed back to the generator, causing damage to the generator or abnormal startup. That is, when there are two power supplies in parallel to supply power to the load at the same time, different power supplies have different power supply priorities. When a sudden load change occurs, it is easy for the power supply with a high power supply priority to charge the power supply with a low power supply priority, causing damage to the power supply with a low power supply priority.

[0032] Therefore, an embodiment of the present application provides a control method for an inverter, which can solve the problem of current backflow from a power supply with a higher power supply priority to a power supply with a lower power supply priority caused by a sudden load change when two power supplies are connected in parallel.

[0033] The technical solution of the present application is further described in detail below in conjunction with the accompanying drawings.

[0034] See also Figure 1 , shows an application scenario of the control method of the converter provided in an embodiment of the present application. This scenario includes a first power source 100, a second power source 200, a converter 300, an AC bus AC_BUS, a load 400 and a controller 500.

[0035] Specifically, the first power supply 100 is connected to the input end of the converter 300, the output end of the converter 300 is connected in parallel with the output end of the second power supply 200 to the AC bus AC_BUS, and the load 400 is also connected to the AC bus AC_BUS. Among them, the first power supply 100 and the second power supply 200 are different power supplies. The load 400 can be any electronic load that can consume alternating current. The converter 300 can adopt a corresponding power conversion circuit according to actual conditions (such as the parameters and specifications of the first power supply 100 and the load 400, etc.).

[0036] In some embodiments, the output power of the first power supply 100 is different from the specification requirements of the load 400, and it needs to be converted before it can be supplied to the load 400. The output power of the second power supply 200 meets the specification requirements of the load 400 and can be directly supplied to the load 400. In one embodiment, the first power supply 100 can be an energy storage power supply, a photovoltaic power generation device, or other power supplies that can provide direct current. The energy storage power supply includes a battery pack, or multiple battery packs connected in series, in parallel, or in series and parallel. The second power supply 200 can be a generator or other power supply that can provide alternating current, wherein the generator can be, for example, a wind turbine, a gasoline generator, a diesel generator, or a hybrid generator. The converter 300 can be an inverter, and its topology can be selected accordingly according to actual needs, and is not specifically limited here. The converter 300 can be used to invert the direct current output by the first power supply 100 into alternating current and then transmit it to the AC bus AC_BUS, and the second power supply 200 can be used to output alternating current to the AC bus AC_BUS. Therefore, the converter 300 and the second power supply 200 can both supply power to the load 400 through the AC bus AC_BUS.

[0037] The controller 500 may be a microcontroller unit (MCU) or other control circuits. The controller 500 may be independently configured or integrated into the first power source 100, the converter 300 or the like. Figure 1 The controller 500 can be used as an EMS (Energy Management System). The controller 500 is connected to the first power supply 100, the converter 300 and the second power supply 200, and can be used to control the operation of the first power supply 100, the converter 300 and the second power supply 200, and realize power distribution and scheduling of the first power supply 100, the converter 300 and the second power supply 200.

[0038] In the embodiment of the present application, the power supply priority of the first power supply 100 is higher than the power supply priority of the second power supply 200. Therefore, when power is required to the load 400, under the control of the controller 500, the converter 300 will supply the power of the first power supply 100 to the load 400 first.

[0039] Among them, if the demand power of the load 400 is not greater than the output power of the converter 300, the converter 300 is solely loaded. In some embodiments, the AC bus AC_BUS can also be connected to a power grid (not shown). Therefore, the converter 300 can also be in a grid-connected load operation state or an off-grid load operation state according to actual conditions. In addition, when the converter 300 is connected to the grid, the output power of the converter 300 can be fed into the power grid in addition to supplying the load 400. The output power of the second power supply 200 can also be fed into the power grid.

[0040] If the power demand of the load 400 is greater than the output power of the converter 300, the converter 300 and the second power source 200 will carry the load together. Specifically, the converter 300 will output with the maximum power first, and the power difference will be supplemented by the second power source 200, so that the sum of the output power of the converter 300 and the output power of the second power source 200 can reach the power demand of the load 400.

[0041] If the sum of the output power of the converter 300 and the output power of the second power source 200 fails to reach the required power of the load 400, at least one of the converter 300 and the second power source 200 can supply power to the load 400 together with the grid, or the grid can supply power to the load 400.

[0042] In the process of the converter 300 supplying power first and being off-grid, the output power of the converter 300 may be greater than the output power of the second power source 200. In this case, when the load 400 on the AC bus AC_BUS is suddenly reduced or completely unloaded (that is, the power demand of the load 400 suddenly decreases), since the traditional control method of the converter 300 cannot respond to the sudden change of load quickly, and the adjustment time of the output power of the converter 300 is also relatively long, the output power of the converter 300 will exceed the power demand of the load 400 after the sudden change for a long time, and the excess power will be transmitted to the second power source 200 through the AC bus AC_BUS, thereby causing the current of the converter 300 to flow back to the second power source 200. For example, assuming that the current power of the load 400 is 5kW, the converter 300 is off-grid and can provide 3kW of power, and the second power source 200 can provide 2kW of power. If the load 400 is suddenly unloaded or suddenly reduced at this time, under the traditional control method, the controller 500 cannot quickly notify the converter 300 to adjust the power, so the converter 300 still outputs with the previous power distribution scheme, that is, the converter 300 still outputs 3kW power. Since there is no load 400 or the load 400 is very light, the 3kW power of the converter 300 minus the power required by the load 400 is still easily higher than the 2kW power of the second power supply 200, so the current of the converter 300 will be fed back to the second power supply 200. During the adjustment process, it is necessary to adjust the output power of the converter 300 to a suitable size through multiple adjustments. Therefore, the current of the converter 300 will continue to be fed back to the second power supply 200. In the long run, the second power supply 200 will be damaged, or the protection mechanism of the second power supply 200 will be triggered, causing the second power supply 200 to shut down or even be damaged.

[0043] Therefore, to deal with this situation, the controller 500 can also be used to execute the inverter control method provided in the embodiment of the present application to control the inverter 300, so that the output of the inverter 300 can follow the sudden change of the load 400, thereby avoiding the current of the inverter 300 from being fed back to the second power supply 200, which is beneficial to the normal operation of the second power supply 200.

[0044] Specifically, please see Figure 2 , the control method of the converter provided in the embodiment of the present application includes:

[0045] Step S11: Obtain a load current value and a preset adjustment coefficient for adjusting the output power of the converter.

[0046] The load current value refers to the actual current value of the load 400. The present application does not specifically limit the method for obtaining the load current value, for example, the controller 500 can obtain the load current value by real-time sampling of the current on the AC bus AC_BUS through a current sampling circuit, or by real-time sampling of the current on the port of the load 400 for connecting to the AC bus AC_BUS through a current sampling circuit.

[0047] The preset adjustment coefficient is a dynamically changeable value, and its size needs to be set accordingly according to the actual situation, and is not limited here. For example, the controller 500 can set the preset adjustment coefficient for the purpose of optimal or economic optimal energy distribution between the off-grid converter 300 and the second power source 200, so as to make the system where the first power source 100 and the off-grid converter 300 are located self-sufficient as much as possible, and the consumables of the second power source 200 are minimized.

[0048] As a further example, for different load conditions, the controller 500 can set different preset adjustment coefficients. For example, in order to make the output power of the converter 300 under heavy load different from the output power of the converter 300 under light load, the preset adjustment coefficient under heavy load can be greater than or less than the preset adjustment coefficient under light load. As another example, different preset adjustment coefficients can also be set for first power supplies 100 of different specifications and operating conditions. For example, the preset adjustment coefficient of the large-capacity first power supply 100 is greater than or less than the preset adjustment coefficient of the small-capacity first power supply 100. For another example, the preset adjustment coefficient of the first power supply 100 when it is fully charged can be greater than or less than the preset adjustment coefficient when the first power supply 100 is not fully charged.

[0049] In step S11, considering that both the load 400 and the first power source 100 may change, the controller 500 may obtain the load current value and the preset adjustment coefficient in real time, and the load current value and the preset adjustment coefficient obtained at different times may be different.

[0050] Step S12: Calculate the current adjustment value according to the load current value and the preset adjustment coefficient.

[0051] In one embodiment, the controller 500 may multiply the load current value and the preset adjustment coefficient, and the obtained product may be used as the current adjustment value. In another embodiment, the controller 500 may also fine-tune the product and then use it as the current adjustment value, or perform other mathematical operations on the load current value and the preset adjustment coefficient to obtain the current adjustment value. The present application does not specifically limit the calculation method of the current adjustment value.

[0052] Step S13: Calculate the reference voltage value of the converter according to the reference output current value of the converter, the current adjustment value, the actual output current value of the converter and the AC bus voltage value.

[0053] Among them, the size of the reference output current value can be set accordingly according to the actual situation (such as the specification parameters of the first power supply 100 and the load 400, etc.), and is not limited here. The actual output current value of the converter 300 can be obtained by real-time sampling of the current at the output end of the converter 300 by the current sampling circuit. It can be understood that when the converter 300 is provided with an output inductor, the current flowing through the output inductor is the actual output current value. Therefore, the actual output current value can also be obtained by real-time sampling of the current of the output inductor by the current sampling circuit. The AC bus voltage value can be obtained by real-time sampling of the voltage on the AC bus AC_BUS by the voltage sampling circuit.

[0054] In step S13, the controller 500 can obtain a reference voltage value by performing closed-loop control on the reference output current value, the current adjustment value, the actual output current value of the converter 300, and the AC bus voltage value of the converter 300. Among them, the loop can be set accordingly according to the actual situation, for example, it can be a combination of a current loop and a voltage loop, or it can be a combination of a current loop, a power loop and a voltage loop, etc., which are not listed here one by one. It can be understood that closed-loop control can improve the control accuracy of the reference voltage value, reduce the deviation, and thus be beneficial to the control effect of the converter 300.

[0055] Step S14: generating an output control signal according to the reference voltage value and the input voltage value of the converter, wherein the output control signal is used to control the output of the converter.

[0056] It can be understood that the input end of the converter 300 is connected to the first power source 100 , and therefore, the input voltage value Vin of the converter 300 is also the output voltage of the first power source 100 .

[0057] In step S14, the controller 500 can perform corresponding mathematical operations on the reference voltage value and the input voltage value according to the hardware topology of the converter 300, and then generate a corresponding output control signal according to the operation result, wherein the operation result carries the duty cycle information of the output control signal. For example, when the converter 300 adopts a two-level topology (two-level means that the output phase voltage has two level states: +Vin / 2, -Vin / 2, and the difference between the two level states is Vin), the controller 500 can divide the reference voltage value by the input voltage value, and then generate an output control signal according to the division result. When the converter 300 adopts a three-level topology (three-level means that the output phase voltage has three level states: +Vin / 2, 0, -Vin / 2, and the difference between two adjacent level states is Vin / 2), the controller 500 can divide the reference voltage value by half of the input voltage value, and then generate an output control signal according to the division result.

[0058] It can be understood that since the converter 300 realizes the current conversion function by switching the internal power switch on and off, the output control signal can be a PWM (Pulse Width Modulation) signal. The PWM signal can be used to control the on and off state of the internal power switch of the converter 300, and further control the output of the converter 300 (including output current, output voltage and output power).

[0059] In summary, in the control method of the converter in the embodiment of the present application, the load current value and the preset adjustment coefficient are obtained, and then the current adjustment value is calculated according to the load current value and the preset adjustment coefficient, and then the reference voltage value of the converter 300 is calculated according to the reference output current value of the converter 300, the current adjustment value, the actual output current value of the converter 300 and the AC bus voltage value, and finally the output control signal of the converter 300 is generated according to the reference voltage value and the input voltage value of the converter 300, thereby controlling the output of the converter 300. Since the load current value will change accordingly with the sudden change of the load (that is, the load power changes), it can be used to characterize the load power and reflect the dynamic change of the load power. Therefore, the control method in the embodiment of the present application introduces the load current value, so that the control process of the converter 300 can be adjusted accordingly due to the change of the load current value, so that the sudden change of the load 400 can be responded to in time. Moreover, the control method of the embodiment of the present application also introduces a preset adjustment coefficient, which can be used to adjust the output power of the converter 300, so that the output of the converter 300 can be adjusted to adapt to the sudden change of the load 400. It can be understood that the control method of the embodiment of the present application can be executed periodically to cope with the sudden change of the load 400 at any time.

[0060] In particular, in the scenario where the generator is used as the second power source 200, the output of the converter 300 is controlled by the control method of the embodiment of the present application, so that the current of the converter 300 is not fed back to the generator due to a sudden change in load, causing damage to the generator or abnormal shutdown. For example, assuming that the current power of the load 400 is 5kW, the converter 300 is off-grid and can provide 3kW power, and the generator can provide 2kW power. If the load 400 is suddenly unloaded or suddenly reduced at this time, the load current value will quickly become 0 or drop sharply. Then, under the control method provided in the embodiment of the present application, the current regulation value will change to 0 or drop sharply with the change of the load current value. Once the current regulation value changes, the output control signal will change accordingly, so the controller 500 can quickly control the output power of the converter 300 by following the output control signal of the current regulation value, thereby realizing the rapid response of the converter 300 to the sudden change in load. Moreover, during the control process, the controller 500 can use a preset adjustment coefficient to adjust the output power of the converter 300 to an appropriate size, so that the converter 300 and the generator can be connected in parallel with equal current and operate normally, avoiding the occurrence of current backflow.

[0061] It should be noted that, in the case where the load 400 is suddenly unloaded or suddenly reduced, the control method of the embodiment of the present application can first use the preset adjustment coefficient of the previous cycle to calculate the current adjustment value. After obtaining the new preset adjustment coefficient, the new current adjustment value is calculated with the new preset adjustment coefficient. Since the load current value is also involved in the calculation of the current adjustment value, even if the current adjustment value is calculated using the preset adjustment coefficient of the previous cycle, the current adjustment value can also become 0 as the load current value becomes 0, or decrease significantly as the load current value decreases significantly, so the method can still obtain an effective current adjustment value, thereby effectively controlling the output of the converter 300.

[0062] In the embodiment of the present application, the control method may determine the preset adjustment coefficient before executing step S11 each time. Therefore, in some embodiments, the control method of the converter may further include:

[0063] A preset adjustment coefficient is obtained according to a power supply parameter of the first power supply.

[0064] Among them, the power parameters of the first power supply 100 include but are not limited to at least one of the state of charge (SOC), power, capacity, output voltage, output current, and output power of the first power supply 100. Furthermore, the power parameters may also include at least one of the actual power parameters, rated power parameters, and target power parameters. Among them, the actual power parameters of the first power supply 100 can be obtained by detecting the first power supply 100 through corresponding detection circuits or detection equipment. The rated power parameters of the first power supply 100 can be pre-recorded and stored or provided by the manufacturer. The target power parameters of the first power supply 100 can be set accordingly according to the actual situation and are not limited here.

[0065] There is a correspondence between the preset adjustment coefficient and one or more power parameters of the first power supply 100, and the correspondence can be set accordingly according to actual conditions, and this application does not make specific limitations on this. Therefore, after obtaining the power parameters of the first power supply 100, the controller 500 can find out the preset adjustment coefficient corresponding to the power parameters according to the preset correspondence.

[0066] For example, there may be a preset corresponding relationship of positive correlation between the preset adjustment coefficient and the actual state of charge of the first power supply 100. Therefore, the controller 500 may obtain the preset adjustment coefficient according to the actual state of charge of the first power supply 100. If the actual state of charge of the first power supply 100 is larger, it means that more power can be allocated, and the obtained preset adjustment coefficient is larger. If the actual state of charge of the first power supply 100 is smaller, it means that less power can be allocated, and the obtained preset adjustment coefficient is smaller. Therefore, the preset adjustment coefficient may also reflect the power distribution of the converter 300.

[0067] Further examples such as Figure 3 As shown, the process of obtaining a preset adjustment coefficient according to the power supply parameter of the first power supply may include:

[0068] Step S21: confirm whether the actual state of charge of the first power source is greater than a first preset threshold value. If yes, proceed to step S22. If no, proceed to step S23.

[0069] Step S22: when the actual state of charge of the first power source is greater than a first preset threshold, determining that the preset adjustment coefficient is equal to the first preset adjustment value.

[0070] Step S23: confirm whether the actual state of charge of the first power source is between the first preset threshold and the second preset threshold. If yes, proceed to step S24. If no, proceed to step S25.

[0071] Step S24: when the actual state of charge of the first power source is between the first preset threshold and the second preset threshold, determining that the preset adjustment coefficient is equal to the second preset adjustment value.

[0072] Step S25: when the actual state of charge of the first power source is not between the first preset threshold and the second preset threshold, that is, is less than the second preset threshold, determining that the preset adjustment coefficient is equal to the third preset adjustment value.

[0073] Among them, the first preset threshold is greater than the second preset threshold, the first preset adjustment value, the second preset adjustment value and the third preset adjustment value are sequentially reduced, and the specific values ​​of these thresholds and adjustment values ​​can be set accordingly according to actual conditions, as long as such a size relationship is satisfied. For example, in one embodiment, the first preset threshold can be set to 80%, and the second preset threshold can be set to 30%. The first preset adjustment value can be set to 1 (i.e., the converter 300 has priority output), the second preset adjustment value can be set to 0.5 (i.e., the converter 300 and the second power supply 200 each bear half of the load power), and the third preset adjustment value can be set to 0.2 (i.e., the converter 300 bears 20% of the load power).

[0074] For another example, the controller 500 can configure the target power parameters of the first power supply 100 according to its control strategy, and obtain the preset adjustment coefficient according to the configured target power parameters. The control strategy of the controller 500 can be set accordingly according to the actual situation, and is not limited here. For example, when the controller 500 controls the first power supply 100 to work in the energy-saving mode, the target output power of the first power supply 100 can be configured to be less than the target output power of the first power supply 100 in the normal mode, and then the preset adjustment coefficient in the energy-saving mode that is different from the preset adjustment coefficient in the normal mode can be determined. For another example, when the controller 500 controls the first power supply 100 to discharge at a certain power, but the controller 500 predicts that it will easily cause corresponding abnormalities or problems after maintaining this discharge power for a certain period of time, the target output power of the first power supply 100 will be reduced, based on which, the corresponding preset adjustment coefficient can be determined according to the reduced target output power. For another example, when the controller 500 performs balanced control on multiple battery packs in the first power supply 100, the corresponding preset adjustment coefficient can be determined according to the target output power required for balanced control.

[0075] In general, the embodiment of the present application can determine a preset adjustment parameter of a suitable size according to the power supply parameters of the first power supply. Based on this preset adjustment coefficient, the output of the converter 300 can be effectively controlled to match the load condition after the sudden change.

[0076] It can be understood that the above-described method for obtaining the preset adjustment coefficient is only an illustrative example provided in the present application. In other embodiments, the preset adjustment coefficient can also be obtained by other methods. For example, in the process of determining the preset adjustment coefficient based on the power parameters of the first power supply, it can also be determined in combination with the power parameters of the second power supply, the parameters of the load and / or the price of consumables of the second power supply, etc., so as to more reasonably allocate the electrical energy of the first power supply and the second power supply, etc., which are not listed one by one here.

[0077] In addition, in some embodiments, the reference output current value of the converter may be determined before executing step S13. Figure 4 , the control method of the converter may further include:

[0078] Step S31: Obtain the input voltage value and input voltage target value of the converter.

[0079] The input voltage target value is the input voltage value that the converter 300 expects to obtain from the first power source 100 .

[0080] Step S32: After performing deviation adjustment on the difference between the input voltage value of the converter and the input voltage target value, a reference current amplitude is obtained.

[0081] That is to say, the input voltage value of the converter 300 can be subtracted from the input voltage target value to obtain a voltage difference, and then the voltage difference is subjected to deviation adjustment to obtain a reference current amplitude. The deviation adjustment can be PI adjustment (Proportional Integral adjustment), PID (Proportional Integral Derivative) adjustment or other adjustment methods, which are not limited here.

[0082] In one embodiment, the voltage difference may be limited and then deviation adjusted to obtain a reference current amplitude of appropriate size to avoid the reference current amplitude being too large to affect the duty cycle information of the output control signal, thereby affecting the effect of suppressing the current backflow of the converter 300 to the second power supply 200.

[0083] Step S33: Calculate the reference output current value of the converter according to the reference current amplitude and the output current phase.

[0084] The output current phase can be generated by a signal generator or a phase-locked loop circuit. The output current phase can be determined according to the actual situation. For example, since the load 400 can be powered by the power grid or the converter 300, the current of the load 400, the AC current provided by the power grid, and the actual output current value of the converter 300 should be the same at least in phase and frequency. Therefore, the output current phase can use a phase signal that is in phase with the AC current of the power grid or the actual output current value and changes in a sinusoidal pattern.

[0085] In step S33, the reference current amplitude and the output current phase may be multiplied to obtain a reference output current value that changes in a sinusoidal manner.

[0086] In general, through the above process, the reference output current value of the converter 300 can be obtained. Since this process is a voltage loop control process with high control accuracy, the deviation of the reference output current value can be small, which is beneficial to the subsequent control effect of the converter 300.

[0087] In one embodiment, the reference output current value and the current adjustment value can be used together as the given value of the current loop of the converter 300. Figure 5 The process of calculating the reference voltage value of the converter according to the reference output current value of the converter, the current adjustment value, the actual output current value of the converter and the AC bus voltage value (i.e., step S13) may include:

[0088] Step S131: Calculate and obtain a target output current value according to a reference output current value and a current adjustment value.

[0089] In one embodiment, the reference output current value and the current adjustment value may be added to obtain the target output current value.

[0090] Step S132: After performing deviation adjustment on the difference between the target output current value and the actual output current value of the converter, an initial voltage value is obtained.

[0091] That is, the target output current value can be subtracted from the actual output current value to obtain a current difference value, and then the current difference value is adjusted by PI adjustment, PID adjustment or other methods to obtain the initial voltage value.

[0092] Step S133: Obtain a reference voltage value of the converter according to the initial voltage value and the AC bus voltage value.

[0093] In one embodiment, the initial voltage value and the AC bus voltage value may be subtracted to obtain a reference voltage value. In another embodiment, the initial voltage value may be subjected to amplitude limiting and then subtracted from the AC bus voltage value to obtain a reference voltage value of appropriate size, so that the reference voltage value may be prevented from being too large to affect the duty cycle information of the output control signal, thereby affecting the effect of suppressing the current backflow of the converter 300 to the second power supply 200.

[0094] Therefore, through steps S131 to S133, the reference voltage value of the converter 300 can be determined. Figure 4 It can be seen that the control process of the converter 300 is a control process that combines a voltage loop and a current loop, and has a high response speed and control accuracy. Therefore, the output of the converter 300 can be controlled quickly and accurately, so that the output current of the converter 300 is of appropriate size and will not be too large to be fed back to the second power supply 200.

[0095] In addition, as mentioned above, Figure 1 The converter 300 in the scenario can be used as a current source, and the second power source 200 can be used as a voltage source. Therefore, the second power source 200 can be started before the converter 300 to provide voltage for the converter 300. Figure 6 As shown, before step S11, the control method of the embodiment of the present application may further include:

[0096] Step S41: upon receiving a discharge instruction, controlling the second power supply to start.

[0097] In one embodiment, the controller 500 can be connected to the device or APP to receive a discharge instruction sent by the device or APP. The discharge instruction can be used to instruct the controller 500 to control the second power supply 200 to start. The communication connection method is not limited, for example, it can be Bluetooth, ZigBee, Wi-Fi, power line carrier communication, star flash and other wireless communication methods.

[0098] Step S42: After the second power supply is started, the converter is controlled to be connected to the grid.

[0099] It can be understood that after the second power supply 200 is started, a voltage can be provided to the converter 300, so that the converter 300 is powered on and starts and enters the operating state. As mentioned above, the actual output current value of the converter 300 is in the same phase and frequency as the AC current provided by the power grid. Therefore, in step S42, the converter 300 can be controlled to be in the grid-connected operating state after the second power supply 200 is started.

[0100] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should know that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously.

[0101] In addition, in one embodiment of the present application, it is also possible to Figure 7 The control loop shown is implemented Figure 2 , Figure 4 and Figure 5 The control method of the converter shown.

[0102] like Figure 7 As shown, the control loop includes a first multiplier 601, a first adder 602, a first subtractor 603, a first deviation regulator 604, a first limiter 605, a second multiplier 606, a second subtractor 607, a second deviation regulator 608, a second limiter 609, a third subtractor 610, a divider 611 and a modulator 612.

[0103] Specifically, the load current value Io and the preset adjustment coefficient K are respectively input into the first multiplier 601 . After the first multiplier 601 multiplies the load current value Io and the preset adjustment coefficient K, it outputs the current adjustment value Io*K to the first adder 602 .

[0104] The input voltage value Vin and the input voltage target value Vin_set of the converter are respectively input to the first subtractor 603, which subtracts the input voltage value Vin and the input voltage target value Vin_set to obtain the corresponding difference Vin_set-Vin, and outputs the difference Vin_set-Vin to the first deviation regulator 604. The difference Vin_set-Vin is biased by the first deviation regulator 604 and then transmitted to the first limiter 605 for limiting processing, thereby obtaining the reference current amplitude Im. The reference current amplitude Im and the output current phase sinθ are respectively input to the second multiplier 606, which multiplies the reference current amplitude Im and the output current phase sinθ to obtain the reference output current value Iref and transmits it to the first adder 602.

[0105] The first adder 602 adds the current adjustment value Io*K and the reference output current value Iref, and outputs the target output current value Iset to the second subtractor 607. The actual output current value IL of the converter is also input to the second subtractor 607. The second subtractor 607 subtracts the target output current value Iset from the actual output current value IL, and outputs the corresponding difference Iset-IL to the second deviation regulator 608. The difference Iset-IL is bias-adjusted by the second deviation regulator 608 and then transmitted to the second limiter 609 for limiting processing, thereby obtaining the initial voltage value Vm. After the initial voltage value Vm is subtracted from the AC bus voltage value Vac_bus, the reference voltage value Vref of the converter is output to the divider 611. The divider 611 performs a corresponding division operation on the reference voltage value Vref and the input voltage value of the converter, and outputs the operation result carrying the duty cycle information to the modulator 612. Finally, the modulator 612 can generate a corresponding output control signal according to the calculation result carrying the duty cycle information. The output control signal can be output to the converter to control the output of the converter.

[0106] It should be noted that the control loop may be located in the controller 500. Moreover, the control loop described above is only an illustrative example provided by the present application, and the present application does not limit the specific composition of the control loop. For example, some links may be omitted (such as omitting the first limiter 605 or the second limiter 609), and some links may be combined or split, etc., which may be adjusted accordingly according to actual conditions, all within the protection scope of the present application.

[0107] It can be understood that the embodiment of the present application also provides a power conversion device.

[0108] Please refer again Figure 1 The power conversion device 600 includes a converter 300 and a controller 500. The converter 300 and the controller 500 can be applied to Figure 1 In the illustrated scenario, the controller 500 can be used to execute the aforementioned converter control method to control the converter 300. It should be understood that other descriptions of the converter 300 and the controller 500 can refer to the relevant records in the aforementioned method embodiment, and will not be repeated here.

[0109] In addition, an embodiment of the present application also provides an energy storage power supply system.

[0110] Please continue reading Figure 1, the energy storage power supply system 1000 includes a first power supply 100 and a power conversion device 600. The first power supply 100 and the power conversion device 600 can refer to the relevant descriptions in the above embodiments, and will not be repeated here. The first power supply 100 and the power conversion device 600 can be set independently, and in actual use, they can also be connected by a cable so that the first power supply 100 supplies power to the load through the power conversion device 600.

[0111] In one embodiment, the first power supply 100 may be an energy storage power supply, and the second power supply 200 connected in parallel with the power conversion device 600 may be a generator. Therefore, the energy storage power supply system 1000 may constitute a hybrid power supply system of an energy storage power supply and a generator together with the generator. The energy storage power supply system 1000 may coordinate with the generator according to the load conditions, which is beneficial to improving the power supply self-sufficiency capability and the reliability of load power supply.

[0112] See also Figure 8 , shows a structural schematic diagram of an electronic device provided in an embodiment of the present application.

[0113] like Figure 8 As shown, electronic device 700 may include a processor 701 and a memory 702 .

[0114] The processor 701 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0115] The memory 702 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 702 may exist independently and be connected to the processor 701 via a bus. The memory 702 may also be integrated with the processor 701.

[0116] The memory 702 is used to store programs, instructions or codes for executing the above converter control method. The processor 701 is used to execute the programs, instructions or codes stored in the memory 702. The programs, instructions or codes stored in the memory 702 can be executed. Figures 2 to 6 Part or all of the steps of the method for controlling the converter in the embodiment shown in FIG.

[0117] See also Fig. 9 , shows a schematic diagram of a control device for a converter provided in an embodiment of the present application. The control device 800 for a converter can be used to implement the control method for the converter described above.

[0118] Specifically, Fig. 9 As shown, the control device 800 of the converter includes an acquisition module 801 , a first calculation module 802 , a second calculation module 803 and a generation module 804 .

[0119] The acquisition module 801 is used to acquire the load current value and a preset adjustment coefficient for adjusting the output power of the converter.

[0120] The first calculation module 802 is used to calculate a current adjustment value according to a load current value and a preset adjustment coefficient.

[0121] The second calculation module 803 is used to calculate the reference voltage value of the converter according to the reference output current value of the converter, the current adjustment value, the actual output current value of the converter and the AC bus voltage value.

[0122] The generating module 804 is used to generate an output control signal according to a reference voltage value and an input voltage value of the converter, and the output control signal is used to control the output of the converter.

[0123] It can be understood that the division of the various modules in the above-mentioned converter control device 800 is only for illustrative purposes. In other embodiments, the converter control device 800 can be divided into different modules as needed to complete all or part of the functions of the above-mentioned converter control device 800.

[0124] The specific implementation of each module in the embodiment of the present application can also refer to Figures 2 to 6 The corresponding description of the method embodiment is shown, so it will not be described in detail here.

[0125] The functional modules in the embodiments of the present application may all be integrated into one processing module / unit, or each module may be a separate module, or two or more modules may be integrated into one module; the above-mentioned integrated modules may be implemented in the form of hardware or in the form of hardware plus software functional modules.

[0126] If the above-mentioned integrated module of the present application is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the embodiment of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROM, RAM, magnetic disks or optical disks.

[0127] The present application also provides a computer-readable storage medium for storing a computer program or code. When the computer program or code is loaded and executed by a processor, the above Figures 2 to 6 All or part of the steps in the control method embodiment of the converter shown. Among them, the computer-readable storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). The specific implementation of the computer-readable storage medium can be found in Figure 8 The description of the memory 702 in will not be repeated here.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the preferred embodiments, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. A control method for a converter, wherein the input end of the converter is used to connect to a first power supply, and the output end of the converter is used to be connected to an AC bus in parallel with the output end of a second power supply; the AC bus is used to connect to a load; the power supply priority of the first power supply is higher than the power supply priority of the second power supply; characterized in that: The control method comprises: Obtaining a load current value and a preset adjustment coefficient for adjusting the output power of the converter; Calculating a current adjustment value according to the load current value and the preset adjustment coefficient; Calculating a reference voltage value of the converter according to a reference output current value of the converter, the current adjustment value, an actual output current value of the converter and an AC bus voltage value; An output control signal is generated according to the reference voltage value and the input voltage value of the converter, and the output control signal is used to control the output of the converter.

2. The control method according to claim 1, characterized in that: The control method further comprises: The preset adjustment coefficient is obtained according to a power supply parameter of the first power supply.

3. The control method according to claim 2, characterized in that: The power supply parameter of the first power supply includes an actual state of charge of the first power supply, and the size of the preset adjustment coefficient is positively correlated with the size of the actual state of charge of the first power supply.

4. The control method according to claim 3, characterized in that: The obtaining the preset adjustment coefficient according to the power supply parameter of the first power supply includes: When the actual state of charge of the first power source is greater than a first preset threshold, determining that the preset adjustment coefficient is equal to a first preset adjustment value; When the actual state of charge of the first power source is between the first preset threshold and the second preset threshold, determining that the preset adjustment coefficient is equal to the second preset adjustment value; When the actual state of charge of the first power source is less than the second preset threshold, determining that the preset adjustment coefficient is equal to a third preset adjustment value; The first preset threshold is greater than the second preset threshold, and the first preset adjustment value, the second preset adjustment value and the third preset adjustment value decrease in sequence.

5. The control method according to claim 1, characterized in that: The step of calculating the reference voltage value of the converter according to the reference output current value of the converter, the current adjustment value, the actual output current value of the converter and the AC bus voltage value comprises: Calculating a target output current value according to the reference output current value and the current adjustment value; After performing deviation adjustment on the difference between the target output current value and the actual output current value of the converter, an initial voltage value is obtained; The reference voltage value of the converter is obtained according to the initial voltage value and the AC bus voltage value.

6. The control method according to claim 1, characterized in that: The control method further comprises: Obtaining an input voltage value and an input voltage target value of the converter; After performing deviation adjustment on the difference between the input voltage value of the converter and the input voltage target value, a reference current amplitude is obtained; A reference output current value of the converter is calculated based on the reference current amplitude and the output current phase.

7. The control method according to claim 1, characterized in that: The control method further comprises: When receiving a discharge instruction, controlling the second power supply to start; After the second power supply is started, the converter is controlled to be connected to the grid.

8. A power conversion device, characterized in that: The power conversion device includes an inverter and a controller, the input end of the inverter is used to connect to a first power supply, and the output end of the inverter is used to be connected to an AC bus in parallel with the output end of a second power supply; the AC bus is used to connect a load; the power supply priority of the first power supply is higher than the power supply priority of the second power supply; the controller is used to execute the control method of the inverter as described in any one of claims 1 to 7.

9. An energy storage power supply system, characterized in that: The energy storage power supply system includes a first power supply and a power conversion device; the power conversion device includes an inverter and a controller, the input end of the inverter is used to connect the first power supply, and the output end of the inverter is used to be connected to an AC bus in parallel with the output end of a second power supply; the AC bus is used to connect a load; the power supply priority of the first power supply is higher than the power supply priority of the second power supply; the controller is used to execute the control method of the inverter as described in any one of claims 1 to 7.

10. The energy storage power supply system according to claim 9, characterized in that: The first power source is an energy storage power source; the second power source is a generator.

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