Control method for converter, power conversion device, and energy storage power supply system

Abstract

A control method for a converter. An input end of the converter is used for being connected to a first power supply; an output end of the converter is used, together with an output end of a second power supply, for being connected in parallel to an alternating current bus; the alternating current bus is used for being connected to 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: first acquiring a load current value and a preset adjustment coefficient; next, calculating a current adjustment value on the basis of the load current value and the preset adjustment coefficient; then calculating a reference voltage value of a converter on the basis of a reference output current value of the converter, the current adjustment value, an actual output current value of the converter and a voltage value of an alternating current bus; and finally generating an output control signal on the basis of the reference voltage value and an input voltage value of the converter to control an output of the converter.

Description

Control method of converter, power conversion device and energy storage power supply system

[0001] Cross-reference to Related Applications

[0002] The present application claims priority from the Chinese patent application No. 202410534863.0 filed on April 29, 2024, and entitled "Control method of converter, power conversion device and energy storage power supply system", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of power supply, in particular to a control method of converter, a power conversion device and an energy storage power supply system. BACKGROUND

[0004] The statements herein are provided only to enhance understanding of the present application and are not necessarily intended to constitute exemplary technology.

[0005] When the energy storage power supply is connected in parallel with the generator to supply power to the load, in the case that the energy storage power supply has sufficient power, the energy storage power supply is usually allowed to supply power to the load preferentially, the energy storage power supply outputs at full power, and the generator supplements the difference. In order to be compatible with the generators on the market, the power conversion system (PCS) of the energy storage power supply usually adopts a current source control mode. However, the current source control mode currently used has the problem that when the load suddenly changes (for example, completely unloads), the current of the PCS is fed back to the generator, which causes damage to the generator or abnormal start of the generator. That is, when two power supplies are connected in parallel to supply power to the load, the power supply priorities of different power supplies are different, and when the load suddenly changes, the power supply with high priority charges the power supply with low priority, which causes damage to the power supply with low priority. SUMMARY

[0006] According to various embodiments of the present application, the present application provides a control method of converter, a power conversion device and an energy storage power supply system.

[0007] The first aspect of the present application provides a control method of a converter, an input end of the converter is used for connecting a first power supply, an output end of the converter is used for connecting, in parallel with an output end of a second power supply, an AC bus; the AC bus is used for connecting a load; a power supply priority of the first power supply is higher than a power supply priority of the second power supply; the control method comprises: acquiring a load current value and a preset adjustment coefficient used for adjusting an 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; and generating an output control signal according to the reference voltage value and an input voltage value of the converter, the output control signal being used for controlling an output of the converter.

[0008] The second aspect of the present application provides a power conversion device, the power conversion device comprising a converter and a controller, an input end of the converter is used for connecting a first power supply, an output end of the converter is used for connecting, in parallel with an output end of a second power supply, an AC bus; the AC bus is used for connecting a load; a power supply priority of the first power supply is higher than a power supply priority of the second power supply; the controller is used for executing the control method of the converter described in the first aspect or any one of the embodiments of the first aspect.

[0009] The third aspect of the present application provides an energy storage power supply system, the energy storage power supply system comprising a first power supply and a power conversion device; the power conversion device comprising a converter and a controller, an input end of the converter is used for connecting the first power supply, an output end of the converter is used for connecting, in parallel with an output end of a second power supply, an AC bus; the AC bus is used for connecting a load; a power supply priority of the first power supply is higher than a power supply priority of the second power supply; the controller is used for executing the control method of the converter described in the first aspect or any one of the embodiments of the first aspect.

[0010] The fourth aspect of the present application provides an electronic device, comprising a processor and a memory, the memory is used for storing programs, instructions or codes, and the processor is used for executing 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.

[0011] The fifth aspect of the present application provides a control device of a converter, comprising an acquisition module, a first calculation module, a second calculation module and a generation module. The acquisition module is used for acquiring a load current value and a preset adjustment coefficient used for adjusting an output power of the converter. The first calculation module is used for calculating a current adjustment value according to the load current value and the preset adjustment coefficient. The second calculation module is used for 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. The generation module is used for generating an output control signal according to the reference voltage value and an input voltage value of the converter, the output control signal being used for controlling an output of the converter.

[0012] The sixth aspect of the present application provides a computer readable storage medium, which stores a computer program. The computer program is loaded by a processor to execute the control method of the converter according to the first aspect or any one of the embodiments of the first aspect.

[0013] In addition, the technical effects brought by any one of the embodiments of the second aspect to the sixth aspect can refer to the technical effects brought by different embodiments of the first aspect, which will not be described here again.

[0014] The details of one or more embodiments of the present application are presented in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments or exemplary technologies of the present application, the drawings needed to be used in the embodiment or exemplary technology description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings of embodiments according to these drawings without creative labor.

[0016] FIG. 1 is a schematic diagram of an application scenario of the control method of the converter according to one of the embodiments of the present application.

[0017] FIG. 2 is a flowchart of the control method of the converter according to one of the embodiments of the present application.

[0018] FIG. 3 is another flowchart of the control method of the converter according to one of the embodiments of the present application.

[0019] FIG. 4 is a detailed flowchart of step S13 in FIG. 2.

[0020] FIG. 5 is another flowchart of the control method of the converter according to one of the embodiments of the present application.

[0021] FIG. 6 is another flowchart of the control method of the converter according to one of the embodiments of the present application.

[0022] FIG. 7 is a control block diagram of the control method of the converter according to one of the embodiments of the present application.

[0023] FIG. 8 is a schematic diagram of an electronic device according to one of the embodiments of the present application.

[0024] FIG. 9 is a schematic diagram of a control device of the converter according to one of the embodiments of the present application. DETAILED DESCRIPTION

[0025] It should be noted that the terms "first", "second", "third" in the specification and claims of the present application and the drawings are used to distinguish similar objects, and are not used to describe a specific order or sequence.

[0026] In addition, it should 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, and the execution order of the steps can be interchanged with each other without departing from the scope of the claims, and some steps can also be deleted.

[0027] Some embodiments will be described below with reference to the accompanying drawings. The following embodiments and features in the embodiments can be combined with each other without conflict.

[0028] When the energy storage power supply is connected in parallel with the generator to supply power to the load, in the case that the energy storage power supply has sufficient power, the energy storage power supply is usually allowed to supply power to the load preferentially, the energy storage power supply outputs at full power, and the generator supplements the difference in power supply. At this time, the power conversion system (PCS) of the energy storage power supply can adopt a voltage source control mode or a current source control mode. When the energy storage power supply adopts the voltage source control mode, inertia and damping need to be introduced to make the PCS have similar mechanical characteristics as the generator, so that in the starting 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 mode accordingly to adapt to different inertia and damping, and such a control mode is complex, has poor robustness, and is difficult to debug. In order to adapt to the generators on the market, the power conversion system (PCS) in the energy storage power supply usually adopts a current source control mode. The current source control mode can make its output track the changes of load disturbance. However, the current source control mode is difficult to respond quickly when the load mutates (for example, completely unloads), which can cause the current output by the PCS to be fed back to the generator, resulting in damage or abnormal start of the generator. That is, when two power supplies are connected in parallel to supply power to the load, the power supply priorities of different power supplies are different, and when the load mutates, the power supply with high power supply priority can easily charge the power supply with low power supply priority, thereby causing damage to the power supply with low power supply priority.

[0029] Therefore, the embodiments of the present application provide a control method of a power conversion system, which can solve the problem that the current of the power supply with high power supply priority is fed back to the power supply with low power supply priority due to load mutation when two power supplies are connected in parallel to supply power to the load.

[0030] The technical solutions of the present application will be described in further detail below with reference to the accompanying drawings.

[0031] Please refer to FIG. 1, which shows an application scenario of the control method of the converter provided in the embodiments. The scenario includes a first power supply 100, a second power supply 200, a converter 300, an AC bus AC_BUS, a load 400, and a controller 500.

[0032] 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. The load 400 is also connected to the AC bus AC_BUS. The first power supply 100 and the second power supply 200 are different power supplies. The load 400 can be any kind of electronic load that can consume AC power. The converter 300 can adopt a corresponding power conversion circuit according to actual conditions (such as the parameter specifications of the first power supply 100 and the load 400).

[0033] In some embodiments, the output power of the first power supply 100 is different from the specification requirement of the load 400 and needs to be converted before being supplied to the load 400. The output power of the second power supply 200 meets the specification requirement of the load 400 and can be directly supplied to the load 400. In an 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 DC power. The energy storage power supply includes a battery pack, and the energy storage battery can also include multiple battery packs connected in series, in parallel, or in series-parallel. The second power supply 200 can be a generator or other power supplies that can provide AC power, such as a wind turbine generator, a gasoline generator, a diesel generator, a vehicle-mounted generator, or a hybrid generator. The converter 300 can be an inverter, and its topology structure can be selected according to actual needs, which is not specifically limited here. The converter 300 can be used to convert the DC power output by the first power supply 100 into AC power and then transmit it to the AC bus AC_BUS. The second power supply 200 can be used to output AC power 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.

[0034] The controller 500 can adopt a microcontroller unit (MCU) or other control circuits. The controller 500 can be independently set or integrated into the first power supply 100, the converter 300, or other devices in the scenario of FIG. 1. The controller 500 can serve 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, thereby realizing power distribution and scheduling of the first power supply 100, the converter 300, and the second power supply 200.

[0035] In the embodiments of the present application, the power supply priority of the first power supply 100 is higher than that of the second power supply 200. Therefore, when the load 400 needs to be powered, the converter 300 will preferentially supply the load 400 with power from the first power supply 100 under the control of the controller 500.

[0036] If the required power of the load 400 is not greater than the output power of the converter 300, the load 400 is powered by the converter 300 alone. In some embodiments, the AC bus AC_BUS can also be connected to a power grid (not shown in the figure). Therefore, the converter 300 can also operate in a grid-connected load carrying state or an off-grid load carrying state according to actual conditions. In addition, when the converter 300 is connected to the grid, the excess part of the output power of the converter 300 can also be fed into the grid in addition to being supplied to the load 400. The output power of the second power supply 200 can also be fed into the grid.

[0037] If the required power of the load 400 is greater than the output power of the converter 300, the load 400 is powered by the converter 300 and the second power supply 200 together. Specifically, the converter 300 will preferentially output at the maximum power, and the second power supply 200 will make up the power difference, so that the sum of the output power of the converter 300 and the output power of the second power supply 200 can reach the required power of the load 400.

[0038] If the sum of the output power of the converter 300 and the output power of the second power supply 200 fails to reach the required power of the load 400, at least one of the converter 300 and the second power supply 200 can supply power to the load 400 together with the grid, or the load 400 can be powered by the grid.

[0039] In the process of the above-mentioned converter 300 preferentially supplying power and being off-grid, the output power of the converter 300 can be greater than the output power of the second power supply 200. In such a case, when the load 400 on the AC bus AC_BUS suddenly lightens or is completely unloaded, that is, the demand power of the load 400 suddenly drops, since the conventional converter 300 control mode cannot quickly respond to the load mutation and the adjustment time of the converter 300 output power is relatively long, the output power of the converter 300 will exceed the demand power of the load 400 after the mutation for a long time, and the excess power will be transmitted to the second power supply 200 through the AC bus AC_BUS, thereby causing the current of the converter 300 to flow back to the second power supply 200. For example, it is assumed that the current power of the load 400 is 5 kW (kilowatt), the converter 300 is off-grid and can provide 3 kW power, and the second power supply 200 can provide 2 kW power. If the load 400 is suddenly unloaded or suddenly lightens at this time, under the conventional control mode, the controller 500 cannot quickly notify the converter 300 to adjust the power, so the converter 300 still outputs according to the previous power allocation scheme, that is, the converter 300 still outputs 3 kW power. Since there is no load 400 or the load 400 is very light, the 3 kW power of the converter 300 minus the power required by the load 400 is still likely to be higher than the 2 kW power of the second power supply 200, so the current of the converter 300 will flow back to the second power supply 200. During the adjustment process, the output power of the converter 300 needs to be adjusted multiple times to be reduced to an appropriate size, so the current of the converter 300 will continue to flow back to the second power supply 200. In the long run, it will cause damage to the second power supply 200 or trigger the protection mechanism of the second power supply 200, resulting in shutdown or even damage of the second power supply 200.

[0040] Therefore, to cope with this situation, the controller 500 can also be used to execute the control method of the converter provided in the embodiments of the present application to control the converter 300, so that the output of the converter 300 can follow the mutation of the load 400, thereby avoiding the current of the converter 300 flowing back to the second power supply 200, and being beneficial to the normal operation of the second power supply 200.

[0041] Specifically, referring to FIG. 2, the control method of the converter provided in the embodiments of the present application comprises:

[0042] Step S11: acquiring a load current value and a preset adjustment coefficient for adjusting the output power of the converter.

[0043] The load current value refers to the actual current value of the load 400. The application does not make specific limitations on the acquisition method of the load current value. For example, the controller 500 can obtain the current on the AC bus AC_BUS through real-time sampling by a current sampling circuit, or obtain the current on the port of the load 400 connected to the AC bus AC_BUS through real-time sampling by a current sampling circuit.

[0044] The preset adjustment coefficient is a dynamically variable value, and its size needs to be set according to the actual situation. This application does not make specific limitations. For example, the controller 500 can set the preset adjustment coefficient for the purpose of optimal energy distribution or economic optimization of the off-grid converter 300 and the second power supply 200, so as to make the system where the first power supply 100 and the off-grid converter 300 are located as self-sufficient as possible, and the amount of consumables of the second power supply 200 is minimized.

[0045] Further examples, for different load conditions, the controller 500 can set different preset adjustment coefficients, for example, to make the output power of the converter 300 under heavy load different from that under light load, the preset adjustment coefficient under heavy load can be greater than or less than that under light load. Another example, for different specifications and operating conditions of the first power supply 100, different preset adjustment coefficients can also be set. For example, the preset adjustment coefficient of the large-capacity first power supply 100 is greater than that of the small-capacity first power supply 100. For example, the preset adjustment coefficient of the first power supply 100 when full can be greater than or less than that when the first power supply 100 is not full.

[0046] In step S11, considering that the load 400 and the first power supply 100 can both change, the controller 500 can 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 can be different.

[0047] Step S12: Calculate the current adjustment value according to the load current value and the preset adjustment coefficient.

[0048] In an embodiment, the controller 500 can multiply the load current value and the preset adjustment coefficient, and the product obtained can be used as the current adjustment value. In another embodiment, the controller 500 can also fine-tune the product before using 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 application does not make specific limitations on the calculation method of the current adjustment value.

[0049] 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.

[0050] The reference output current value can be set according to actual conditions (for example, the specification parameters of the first power supply 100 and the load 400) and is not limited herein. The actual output current value of the converter 300 can be obtained by sampling the current on the output end of the converter 300 in real time 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, and therefore, the actual output current value can also be obtained by sampling the current of the output inductor in real time by the current sampling circuit. The AC bus voltage value can be obtained by sampling the voltage on the AC bus AC_BUS in real time by the voltage sampling circuit.

[0051] In step S13, the controller 500 can derive the reference voltage value by closed-loop control on the reference output current value of the converter 300, the current regulation value, the actual output current value of the converter 300, and the AC bus voltage value. The loop can be set according to actual conditions, for example, it can be a combination of a current loop and a voltage loop, or a combination of a current loop, a power loop, and a voltage loop, and the like, which are not enumerated herein. It can be understood that the 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.

[0052] Step S14: generating 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.

[0053] It can be understood that the input end of the converter 300 is connected to the first power supply 100, and therefore, the input voltage value Vin of the converter 300 is the output voltage of the first power supply 100.

[0054] 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 structure 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 structure (two levels refer to the phase voltage of the output having 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 the output control signal according to the division result. When the converter 300 adopts a three-level topology structure (three levels refer to the phase voltage of the output having three level states: +Vin / 2, 0, -Vin / 2, and the difference between the adjacent two level states is Vin / 2), the controller 500 can divide the reference voltage value by half of the input voltage value, and then generate the output control signal according to the division result.

[0055] It can be understood that, since the converter 300 realizes the conversion function by switching the on-off state of the internal power switch, the output control signal can be a PWM (Pulse Width Modulation) signal. The PWM signal can be used to control the on-off state of the internal power switch of the converter 300, and thus the output (including the output current, the output voltage and the output power) of the converter 300 can also be controlled.

[0056] In summary, in the control method of the converter of the embodiment of the present application, the load current value and the preset adjustment coefficient are obtained, then the current adjustment value is calculated according to the load current value and the preset adjustment coefficient, 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, so as to control the output of the converter 300. Since the load current value will change accordingly when the load suddenly changes (i.e. the load power changes), the load current value can be used to represent the load power and reflect the dynamic change of the load power, therefore, the control method of 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 as to respond to the sudden change of the load 400 in time. Moreover, the control method of the embodiment of the present application also introduces the 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 suddenly changed 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.

[0057] In particular, in the scenario where the generator is the second power source 200, the output of the converter 300 is controlled by the control method of the embodiments of the present application, which can avoid the situation that the current of the converter 300 is back-feeding to the generator due to sudden change of the load, resulting in damage or abnormal shutdown of the generator. For example, it is assumed that the current power of the load 400 is 5kW, the converter 300 is operating 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 greatly decrease. Under the control method provided by the embodiments of the present application, the current regulation value will also become 0 or greatly decrease following the change of the load current value. Once the current regulation value changes, the output control signal will also change accordingly, so that the controller 500 can quickly control the output power of the converter 300 by following the output control signal that changes with the current regulation value, thereby realizing the quick response of the converter 300 to the sudden change of the load. Moreover, in the control process, the controller 500 can use the preset regulation coefficient to adjust the output power of the converter 300 to an appropriate size, so that the converter 300 and the generator can be parallelly connected and operated normally, and the situation of back-feeding of the current can be avoided.

[0058] It should be noted that in the case of sudden unloading or sudden reduction of the load 400, the control method of the embodiments of the present application can first use the preset regulation coefficient of the previous period to calculate the current regulation value. After obtaining the new preset regulation coefficient, the new current regulation value is calculated with the new preset regulation coefficient. Since the load current value also participates in the calculation of the current regulation value, even if the current regulation value is calculated with the preset regulation coefficient of the previous period, the current regulation value can also become 0 following the load current value becoming 0, or greatly decrease following the great decrease of the load current value, so that the method can still obtain an effective current regulation value, thereby effectively controlling the output of the converter 300.

[0059] In the embodiments of the present application, the control method can first determine the preset regulation coefficient before each execution of step S11. Therefore, in some embodiments, the control method of the converter can further include:

[0060] obtaining the preset regulation coefficient according to the power supply parameter of the first power source.

[0061] The power supply parameters of the first power supply 100 include, but are not limited to, at least one of a state of charge (SOC), an electric quantity, a capacity, an output voltage, an output current, and an output power of the first power supply 100. Further, the power supply parameters can also include at least one of an actual power supply parameter, a rated power supply parameter, and a target power supply parameter. The actual power supply parameter of the first power supply 100 can be obtained by detecting the first power supply 100 through a corresponding detection circuit or detection device. The rated power supply parameter of the first power supply 100 can be pre-recorded and stored or provided by a manufacturer. The target power supply parameter of the first power supply 100 can be set according to actual conditions, which is not limited herein.

[0062] The preset adjustment coefficient has a corresponding relationship with one or more power supply parameters of the first power supply 100. The corresponding relationship can be set according to actual conditions, which is not specifically limited herein. Therefore, after obtaining the power supply parameters of the first power supply 100, the controller 500 can find the preset adjustment coefficient corresponding to the power supply parameters according to the preset corresponding relationship.

[0063] For example, the preset adjustment coefficient and the actual state of charge of the first power supply 100 can have a preset corresponding relationship of positive correlation. Therefore, the controller 500 can 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 large, it means that the allocatable power is more, and the obtained preset adjustment coefficient is larger. If the actual state of charge of the first power supply 100 is small, it means that the allocatable power is less, and the obtained preset adjustment coefficient is smaller. Therefore, the preset adjustment coefficient can also reflect the power distribution of the converter 300.

[0064] Further examples, as shown in FIG. 3, the process of obtaining the preset adjustment coefficient according to the power supply parameters of the first power supply can include:

[0065] Step S21: confirming whether the actual state of charge of the first power supply is greater than a first preset threshold. If yes, go to step S22. If no, go to step S23.

[0066] Step S22: when the actual state of charge of the first power supply is greater than the first preset threshold, determining that the preset adjustment coefficient is equal to a first preset adjustment value.

[0067] Step S23: confirming whether the actual state of charge of the first power supply is between a first preset threshold and a second preset threshold. If yes, go to step S24. If no, go to step S25.

[0068] Step S24: when the actual state of charge of the first power supply is between the first preset threshold and the second preset threshold, determining that the preset adjustment coefficient is equal to a second preset adjustment value.

[0069] Step S25: When the actual state of charge of the first power supply is not between the first preset threshold and the second preset threshold, i.e., less than the second preset threshold, it is determined that the preset adjustment coefficient is equal to a third preset adjustment value.

[0070] 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 are sequentially smaller. The specific values of these thresholds and adjustment values can be set according to actual conditions, as long as they meet such a size relationship. For example, in an 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 is preferentially 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. The third preset adjustment value can be set to 0.2, i.e., the converter 300 bears 20% of the load power.

[0071] For another example, the controller 500 can configure the target power supply parameter of the first power supply 100 according to its control strategy, and obtain the preset adjustment coefficient according to the configured target power supply parameter. The control strategy of the controller 500 can be set according to actual conditions, which is not limited herein. For example, when the controller 500 controls the first power supply 100 to work in an energy-saving mode, the target output power of the first power supply 100 in the energy-saving mode can be configured to be less than the target output power of the first power supply 100 in a normal mode, and thus a preset adjustment coefficient in the energy-saving mode different from that 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 maintaining this discharge power for a certain time will easily cause corresponding abnormalities or problems, and thus the target output power of the first power supply 100 will be reduced. Based on this, the corresponding preset adjustment coefficient can be determined according to the reduced target output power. For another example, when the controller 500 controls the plurality of battery packs in the first power supply 100 for equalization control, the corresponding preset adjustment coefficient can be determined according to the target output power required for the equalization control.

[0072] In general, the embodiments of the present application can determine a preset adjustment parameter of appropriate size according to the power supply parameter 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.

[0073] It can be understood that the preset adjustment coefficient obtaining manner described above is only a schematic example provided by the present application, and in other embodiments, the preset adjustment coefficient can also be obtained by other manners. For example, in the process of determining the preset adjustment coefficient according to the power supply parameter of the first power supply, the power supply parameter of the second power supply, the parameter of the load, and / or the price of the consumables of the second power supply can also be combined to determine together, so as to more reasonably allocate the electric energy of the first power supply and the second power supply, and the like, which will not be enumerated here.

[0074] In addition, in some embodiments, the reference output current value of the converter can also be determined before step S13 is performed. Therefore, referring to FIG. 4, the control method of the converter can also include:

[0075] Step S31: obtaining an input voltage value of the converter and an input voltage target value.

[0076] The input voltage target value is an input voltage value that the converter 300 expects to obtain from the first power supply 100.

[0077] Step S32: obtaining a reference current amplitude by performing deviation adjustment on the difference between the input voltage value of the converter and the input voltage target value.

[0078] That is, the input voltage value of the converter 300 can be subtracted from the input voltage target value to obtain a voltage difference value, and then the voltage difference value 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 manners, which are not limited here.

[0079] In an embodiment, the voltage difference value can also be subjected to amplitude limiting processing before the deviation adjustment, to obtain a reference current amplitude of a suitable size, so as to avoid that the reference current amplitude is too large to affect the duty cycle information of the output control signal, and then affect the effect of suppressing the current backflow of the converter 300 to the second power supply 200.

[0080] Step S33: calculating a reference output current value of the converter according to the reference current amplitude and an output current phase.

[0081] The output current phase can be generated by a signal generator or a phase-locked loop circuit, etc. The size of the output current phase can be determined according to actual conditions. For example, since the load 400 can be powered by the power grid or the converter 300, the current of the load 400, the alternating current provided by the power grid, and the actual output current value of the converter 300 are at least the same in phase and frequency. Therefore, the output current phase can adopt a phase signal that is in phase with the alternating current of the power grid or the actual output current value and varies regularly in a sine wave.

[0082] In step S33, the reference current amplitude and the output current phase can be multiplied to obtain a reference output current value that varies regularly in a sine wave.

[0083] 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, it has high control accuracy, and thus the deviation of the reference output current value can be small, thereby facilitating the control effect of the subsequent converter 300.

[0084] In an embodiment, the reference output current value can be used as a given of the current loop of the converter 300 together with the current regulation value. Therefore, referring to FIG. 5, the process of calculating the reference voltage value of the converter according to the reference output current value of the converter, the current regulation value, the actual output current value of the converter, and the alternating bus voltage value (i.e., step S13) can include:

[0085] In step S131, a target output current value is calculated according to the reference output current value and the current regulation value.

[0086] In an embodiment, the reference output current value and the current regulation value can be added to obtain the target output current value.

[0087] In step S132, a voltage initial value is obtained after deviation adjustment is performed on the difference between the target output current value and the actual output current value of the converter.

[0088] 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 adjustment to obtain the voltage initial value.

[0089] In step S133, the reference voltage value of the converter is obtained according to the voltage initial value and the alternating bus voltage value.

[0090] In an embodiment, the reference voltage value can be obtained by subtracting the voltage initial value from the AC bus voltage value. In another embodiment, the reference voltage value can be obtained by subtracting the voltage initial value from the AC bus voltage value after the voltage initial value is limited. In this way, the reference voltage value can be prevented from being too large to affect the duty cycle information of the output control signal, and further affect the effect of suppressing the current backflow of the converter 300 to the second power supply 200.

[0091] Therefore, by steps S131-S133, the reference voltage value of the converter 300 can be determined. As can be seen from FIG. 4, the control process of the converter 300 is a control process combining the voltage loop and the current loop, and has high response speed and control accuracy. Therefore, the output of the converter 300 can be quickly and accurately controlled, so that the output current of the converter 300 is appropriate and will not be too large to backflow to the second power supply 200.

[0092] In addition, as described above, the converter 300 in the scenario of FIG. 1 can act as a current source, and the second power supply 200 can act as a voltage source. Therefore, the second power supply 200 can be started before the converter 300 to provide voltage for the converter 300. Therefore, as shown in FIG. 6, before step S11, the control method of the embodiment of the application can further include:

[0093] Step S41: When the discharge instruction is received, the second power supply is controlled to start.

[0094] In an embodiment, the controller 500 can be in communication connection with the device side or the APP side to receive the discharge instruction sent by the device side or the APP side. The discharge instruction can be used to instruct the controller 500 to control the second power supply 200 to start. The communication connection mode is not limited, for example, it can be a wireless communication mode such as Bluetooth, ZigBee, Wi-Fi, power line carrier communication, star flash, etc.

[0095] Step S42: After the second power supply starts, the converter is controlled to operate in parallel.

[0096] It can be understood that after the second power supply 200 starts, the voltage can be provided to the converter 300, so that the converter 300 is powered on and enters the running state. As described above, the actual output current value of the converter 300 is in phase and frequency with the AC current provided by the power grid. Therefore, in step S42, the converter 300 can be controlled to operate in parallel after the second power supply 200 starts.

[0097] It should be noted that, for the foregoing method embodiments, in order to simply describe, they are all described as a series of action combinations, but those skilled in the art should know that the application is not limited to the action order described, because according to the application, certain steps can be performed in other order or simultaneously.

[0098] In addition, in an embodiment of the present application, the control method of the converter shown in FIGS. 2, 4 and 5 can also be implemented by the control loop shown in FIG. 7.

[0099] As shown in FIG. 7, the control loop includes a first multiplier 601, a first adder 602, a first subtractor 603, a first deviation adjuster 604, a first limiter 605, a second multiplier 606, a second subtractor 607, a second deviation adjuster 608, a second limiter 609, a third subtractor 610, a divider 611 and a modulator 612.

[0100] Specifically, the load current value Io and a preset adjustment coefficient K are input into the first multiplier 601, and the first multiplier 601 multiplies the load current value Io and the preset adjustment coefficient K to output a current adjustment value Io*K to the first adder 602.

[0101] The input voltage value Vin and the input voltage target value Vin_set of the converter are input into the first subtractor 603. The first subtractor 603 subtracts the input voltage value Vin from the input voltage target value Vin_set to obtain a corresponding difference value Vin_set-Vin, and outputs the difference value Vin_set-Vin to the first deviation adjuster 604. The difference value Vin_set-Vin is subjected to deviation adjustment by the first deviation adjuster 604 and then transmitted to the first limiter 605 for limiting processing, so as to obtain a reference current amplitude Im. The reference current amplitude Im and the output current phase sinθ are input into the second multiplier 606. The second multiplier 606 multiplies the reference current amplitude Im and the output current phase sinθ to obtain a reference output current value Iref and transmit it to the first adder 602.

[0102] The first adder 602 adds the current regulation value Io*K and the reference output current value Iref, and outputs a 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, and the second subtractor 607 subtracts the target output current value Iset from the actual output current value IL, and outputs a corresponding difference value Iset-IL to the second deviation adjuster 608. The difference value Iset-IL is subjected to deviation adjustment by the second deviation adjuster 608, and then transmitted to the second limiter 609 for limiting processing, so as to obtain a voltage initial value Um. The voltage initial value Um is subtracted from the AC bus voltage value Vac_bus, and a reference voltage value Vref=Vm-Vac_bus of the converter is output to the divider 611. The divider 611 performs corresponding division operation on the reference voltage value Vref and the input voltage value of the converter, and outputs an operation result carrying duty cycle information to the modulator 612. Finally, the modulator 612 can generate a corresponding output control signal according to the operation result carrying the duty cycle information. The output control signal can be output to the converter, so as to control the output of the converter.

[0103] It should be noted that the control loop can be located in the controller 500. Moreover, the control loop described above is only a schematic example provided by the present application, and the present application does not limit the specific composition of the control loop, for example, part of the links (such as the first limiter 605 or the second limiter 609) can be omitted, part of the links can be combined or split, and the like, and the specific adjustment can be made according to the actual situation, which is within the protection scope of the present application.

[0104] It can be understood that the present application also provides a power conversion device.

[0105] Please refer to Fig. 1 again, the power conversion device 600 comprises the converter 300 and the controller 500. The converter 300 and the controller 500 can be applied to the scenario shown in Fig. 1, and the controller 500 can be used to execute the control method of the converter described above to control the converter 300. It should be understood that other descriptions of the converter 300 and the controller 500 can be referred to the related description in the foregoing method embodiments, which will not be described herein again.

[0106] In addition, the present application also provides an energy storage power supply system.

[0107] Please continue to refer to Fig. 1, the energy storage power supply system 1000 comprises the first power supply 100 and the power conversion device 600. The first power supply 100 and the power conversion device 600 can be referred to the related description in the foregoing embodiments, which will not be described herein again. The first power supply 100 and the power conversion device 600 can be respectively and independently arranged, and in actual use, the first power supply 100 can also be connected through a cable to the power conversion device 600 to supply power to the load through the power conversion device 600.

[0108] In an embodiment, the first power supply 100 can be an energy storage power supply, and the second power supply 200 connected in parallel with the power conversion device 600 can be a generator. Therefore, the energy storage power supply system 1000 can constitute an energy storage power supply and generator hybrid power supply system together with the generator, and the energy storage power supply system 1000 can work in coordination with the generator according to the load condition, which is beneficial to improve the self-provisioning capability of power supply and the reliability of load power supply.

[0109] Please refer to FIG. 8, which shows a structural schematic diagram of an electronic device provided in an embodiment of the present application.

[0110] As shown in FIG. 8, the electronic device 700 can include a processor 701 and a memory 702.

[0111] The processor 701 can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0112] The memory 702 can be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of dynamic storage device that can store information and instructions, an Electrically Erasable Programmable Read-Only Memory (EEPROM), a Compact Disc Read-Only Memory (CD-ROM) or other optical disk storage, a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer, but is not limited to this. The memory 702 can exist independently and be connected to the processor 701 through a bus. The memory 702 can also be integrated with the processor 701.

[0113] The memory 702 is configured to store a program, an instruction or a code for performing the control method of the converter. The processor 701 is configured to execute the program, the instruction or the code stored in the memory 702. The program, the instruction or the code stored in the memory 702 can execute part or all of the steps of the control method of the converter in the embodiments shown in FIGS. 2 to 6.

[0114] Referring to FIG. 9, a schematic diagram of the control device of the converter is shown. The control device 800 of the converter can be used to implement the control method of the converter.

[0115] Specifically, as shown in FIG. 9, the control device 800 of the converter includes an obtaining module 801, a first calculating module 802, a second calculating module 803 and a generating module 804.

[0116] The obtaining module 801 is configured to obtain the load current value, and configured to adjust the preset adjustment coefficient of the output power of the converter.

[0117] The first calculating module 802 is configured to calculate the current adjustment value according to the load current value and the preset adjustment coefficient.

[0118] The second calculating module 803 is configured 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.

[0119] The generating module 804 is configured to generate the 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.

[0120] It can be understood that the division of each module in the control device 800 of the converter is only for example, and in other embodiments, the control device 800 of the converter can be divided into different modules as needed to complete all or part of the functions of the control device 800 of the converter.

[0121] The specific implementation of each module in the embodiments of the present application can also correspond to the description of the corresponding method embodiments shown in FIGS. 2 to 6, and therefore will not be described in detail here.

[0122] The functions of each module in the embodiments of the present application can be integrated into one processing module / unit, or each module can be a separate module, or two or more modules can be integrated into one module; the integrated module can be realized in the form of hardware or in the form of hardware plus software function module.

[0123] The above-mentioned integrated modules of the present application, if realized in the form of software function modules and sold or used as independent products, can also be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the embodiments of the present application can be embodied in the form of a software product, which is stored in a storage medium and includes a plurality of instructions for causing 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 the embodiments of the present application. The aforementioned storage medium includes various media that can store program codes, such as mobile storage devices, ROM, RAM, magnetic or optical disks, etc.

[0124] The embodiments of the present application also provide a computer readable storage medium for storing a computer program or code, which, when loaded and executed by a processor, realizes all or part of the steps in the control method embodiments of the converter shown in FIGS. 2 to 6. 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 refer to the description of the memory 702 in FIG. 8, which will not be described here.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A control method of a converter, an input end of the converter being configured to be connected to a first power supply, an output end of the converter being configured to be connected in parallel to an output end of a second power supply to an AC bus, the AC bus being configured to be connected to a load, a power supply priority of the first power supply being higher than a power supply priority of the second power supply, the control method comprising: obtaining a load current value and a preset adjustment coefficient for adjusting an 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; and generating an output control signal according to the reference voltage value and an input voltage value of the converter, the output control signal being configured to control an output of the converter. The control method further comprises: obtaining the preset adjustment coefficient according to a power supply parameter of the first power supply. The power supply parameter of the first power supply comprises an actual state of charge of the first power supply, and a size of the preset adjustment coefficient is positively correlated with a size of the actual state of charge of the first power supply. The obtaining the preset adjustment coefficient according to the power supply parameter of the first power supply comprises: 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 greater than a first preset threshold; determining that the preset adjustment coefficient is equal to a second preset adjustment value when the actual state of charge of the first power supply is between the first preset threshold and a second preset threshold; and determining that the preset adjustment coefficient is equal to a third preset adjustment value when the actual state of charge of the first power supply is less than the second preset threshold, wherein 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 order. The preset adjustment coefficient is determined according to the power supply parameter of the first power supply, a power supply parameter of the second power supply, a load parameter and a price of a consumable of the second power supply. The 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; obtaining a voltage initial value after deviation adjustment on a difference between the target output current value and the actual output current value of the converter; and obtaining the reference voltage value of the converter according to the voltage initial value and the AC bus voltage value. The control method further comprises: obtaining an input voltage value of the converter and an input voltage target value; obtaining a reference current amplitude value after deviation adjustment on a difference between the input voltage value of the converter and the input voltage target value; and calculating the reference output current value of the converter according to the reference current amplitude value and an output current phase. The control method further comprises: controlling the second power supply to start when a discharge instruction is received. ​ ​ ​ ​ 2. The control method of claim 1, wherein, ​ ​ 3. The control method of claim 2, wherein, ​ 4. The control method of claim 3, wherein, ​ ​ ​ ​ ​ 5. The control method of claim 2, wherein, ​ 6. The control method of claim 1, wherein, ​ ​ ​ ​ 7. The control method of claim 1, wherein, ​ ​ ​ ​ 8. The control method of claim 1, wherein, ​ ​ After the second power source is started, the converter is controlled to operate in grid-connected mode. 9.A power conversion device, comprising a converter and a controller, an input of the converter being configured to be connected to a first power source, an output of the converter being configured to be connected in parallel with an output of a second power source to an AC bus, the AC bus being configured to be connected to a load, the first power source having a higher priority in power supply than the second power source, the controller being configured to perform the method of controlling the converter according to any one of claims 1 to 8. 10.An energy storage power supply system, comprising a first power source and a power conversion device, the power conversion device comprising a converter and a controller, an input of the converter being configured to be connected to the first power source, an output of the converter being configured to be connected in parallel with an output of a second power source to an AC bus, the AC bus being configured to be connected to a load, the first power source having a higher priority in power supply than the second power source, the controller being configured to perform the method of controlling the converter according to any one of claims 1 to 8.

11. The energy storage power supply system of claim 10, wherein, The first power source is an energy storage power source, and the second power source is a generator.

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