A method and device for controlling energy storage converter on-grid and off-grid

Abstract

The present application proposes a method and device for controlling the connection and off-grid operation of an energy storage converter, including, in the grid-connected mode, performing island detection on the common connection point according to the synchronized grid-side voltage, and obtaining the real-time state value of the reactive current; if the real-time state value triggers the island effect, enabling the current limiting operation of the energy storage converter, and switching the energy storage converter to operate in the off-grid mode based on the error adjustment of the energy storage converter; if the real-time state value does not trigger the island effect, maintaining the energy storage converter to operate in the grid-connected mode. By performing island detection on the common connection point, the real-time state value of the reactive current is obtained, and the off-grid mode is identified according to the disturbance of the reactive current and the positive feedback strategy of the common connection point frequency; and by enabling the current limiting operation and error adjustment of the energy storage converter, the operation of the energy storage converter is switched from the grid-connected mode to the off-grid mode, which greatly optimizes the switching time and minimizes the power-off phenomenon of the load output voltage, and has a wide range of applicability.

Description

Technical Field

[0001] The present application relates to the field of energy storage design and application technology, and in particular to a method and device for controlling grid-connection and off-grid connection of an energy storage converter. Background Art

[0002] In energy storage technology, energy storage inverters, as a key link in energy conversion and storage, provide technical support and guarantee for the large-scale application of renewable energy. The switching mode of energy storage inverters from grid-connected to off-grid and from off-grid to grid-connected is mainly achieved through the closing operation between circuit breakers, manual switches and relays to achieve on-grid and off-grid conversion control. Since constant power control is usually used in grid-connected mode, and constant voltage and frequency control is usually used in off-grid mode, there will be an action time of tens to hundreds of milliseconds at the moment of closing, which may cause power failure of the load output voltage.

[0003] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0004] The embodiments of the present application provide a method and device for controlling an energy storage converter on and off the grid.

[0005] The first embodiment of the present application proposes a method for controlling an energy storage converter on and off the grid, including:

[0006] In response to the energy storage converter operating in the grid-connected mode, an island detection is performed on the common connection point according to the synchronized grid-side voltage to obtain a real-time state value of the reactive current, wherein the common connection point is set at a connection position between the grid side and the energy storage converter;

[0007] If the real-time status value triggers an islanding effect, the current limiting operation of the energy storage converter is enabled, and based on the error adjustment of the energy storage converter, the energy storage converter is switched to operate in an off-grid mode;

[0008] If the real-time status value does not trigger an islanding effect, the energy storage converter is maintained to operate in a grid-connected mode.

[0009] The second embodiment of the present application provides a grid-connected and off-grid control device for an energy storage converter, comprising:

[0010] An acquisition module, wherein in response to the energy storage converter operating in the grid-connected mode, the acquisition module performs island detection on the common connection point according to the synchronized grid-side voltage to acquire the real-time state value of the reactive current, wherein the common connection point is set at the connection position between the grid side and the energy storage converter;

[0011] A first regulating module, wherein the first regulating module is used to trigger an islanding effect at the real-time state value, enable a current limiting operation of the energy storage converter, and switch the energy storage converter to operate in an off-grid mode based on an error regulation of the energy storage converter;

[0012] The second regulating module is used for maintaining the energy storage converter to operate in a grid-connected mode when the real-time state value does not trigger an islanding effect.

[0013] The third aspect embodiment of the present application proposes an electronic device, comprising: a processor; a memory for storing instructions executable by the processor; wherein the processor is configured to execute the instructions to implement the energy storage inverter on-grid and off-grid control method proposed in the first aspect embodiment of the present application.

[0014] The fourth aspect embodiment of the present application proposes a non-temporary computer-readable storage medium. When the instructions in the storage medium are executed by the processor of an electronic device, the electronic device can execute the method proposed in the first aspect embodiment of the present application.

[0015] The fifth aspect embodiment of the present application proposes a computer program product, including a computer program, which implements the method proposed in the first aspect embodiment of the present application when executed by a processor in a communication device.

[0016] The technical solution provided by the embodiments of the present application brings at least the following beneficial effects:

[0017] By performing island detection on the common connection point, the real-time state value of the reactive current is obtained, and the off-grid mode is identified based on the disturbance of the reactive current and the positive feedback strategy of the common connection point frequency; and by enabling the current limiting operation and error adjustment of the energy storage inverter, the operation of the energy storage inverter is switched from the grid-connected mode to the off-grid mode, which greatly optimizes the switching time and minimizes the power-off phenomenon of the load output voltage, and has wide applicability.

[0018] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0020] Figure 1 A schematic flow chart of a method for controlling an energy storage converter on and off the grid provided in an embodiment of the present application;

[0021] Figure 2A schematic flow chart of another method for controlling an energy storage converter on and off the grid provided in an embodiment of the present application;

[0022] Figure 3 A schematic diagram of a grid-connected control strategy provided according to an embodiment of the present application;

[0023] Figure 4 A schematic diagram of an off-grid control strategy provided according to an embodiment of the present application;

[0024] Figure 5 A schematic diagram of switching from grid-connected to off-grid provided according to an embodiment of the present application;

[0025] Figure 6 Another schematic diagram of switching from grid-connected to off-grid provided according to an embodiment of the present application;

[0026] Figure 7 A schematic diagram of the structure of an energy storage converter on-grid and off-grid control device provided in an embodiment of the present application;

[0027] Figure 8 A schematic diagram of the structure of an electronic device provided according to an embodiment of the present application;

[0028] Fig. 9 It is a schematic diagram of the structure of another electronic device provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0029] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the embodiments of the present application as detailed in the appended claims.

[0030] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms of "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0031] It should be understood that, although the terms first, second, third, etc. may be used to describe various information in the embodiments of the present application, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the embodiments of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the words "if" and "if" as used herein may be interpreted as "at..." or "when..." or "in response to determination".

[0032] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0033] It should be noted that the energy storage converter on-grid and off-grid control method provided in any embodiment of the present application can be executed alone, or in combination with possible implementation methods in other embodiments, or in combination with any technical solution in the relevant technology.

[0034] The following describes the energy storage converter on-grid and off-grid control method and device according to the embodiment of the present application with reference to the accompanying drawings.

[0035] Figure 1 A schematic flow chart of a method for controlling an energy storage converter on and off the grid provided in an embodiment of the present application.

[0036] like Figure 1 As shown, the energy storage converter on-grid and off-grid control method includes but is not limited to the following steps:

[0037] S101, in response to the energy storage converter operating in the grid-connected mode, an island detection is performed on the common connection point according to the synchronized grid-side voltage to obtain a real-time state value of the reactive current, wherein the common connection point is set at a connection position between the grid side and the energy storage converter.

[0038] In a feasible implementation, in the grid-connected mode, the energy storage inverter can be equivalent to a current source model and accept the power / current scheduling of the energy management system (the energy management system can monitor the operating status of the energy storage system or the power grid in real time, including key parameters such as the voltage, current, and temperature of the battery pack, as well as the operating status of the energy storage inverter and the battery management system). The control loop is composed of an outer power loop and an inner current loop, wherein the outer power loop ensures that the output power of the energy storage inverter can accurately follow the given power instruction (i.e., ensure that the output power matches the set power reference value); the inner current loop is used to respond to the error value of the outer power loop and track the current, thereby achieving control of the power reference value.

[0039] Further, Figure 3 Schematic diagram of a grid-connected control strategy provided according to an embodiment of the present application. Figure 3 As shown, the instantaneous value of the grid side voltage is obtained, and the instantaneous value of the voltage is e a 、e b 、e c ; Then the voltage phase θ is obtained through the phase-locked loop PLL, and the instantaneous values ​​of the three-phase inductor currents are collected. The instantaneous values ​​of the three-phase inductor currents are i inv_a 、i inv_b 、i inv_c , the three-phase inductor current is converted into i through abc / dq d 、i q , where abc / dq conversion is a method of converting a three-phase stationary coordinate system (abc) into a two-phase rotating coordinate system (dq), and this transformation depends on the voltage phase θ; the power outer loop passes through a PI regulator (the PI regulator includes a proportional regulator and an integral regulator, both of which are based on feedback control theory and adjust the output signal according to the size of the input error signal to reduce the error. For example, when the input error signal is greater than the set value, the size of the output signal is increased to reduce the error; when the input error signal is less than the set value, the negative error is attempted to be reduced, that is, the actual value is made closer to the set value) to obtain a reference value This reference value is equal to i d 、i q Compare and get the initial error; after the initial error passes through the PI regulator, its output value is added and subtracted from the feedforward and decoupling terms to get the output voltage value U d , U q Then transform the two-phase rotating coordinate system to the two-phase stationary coordinate system (i.e. 2r / 2s) to obtain the output voltage value U d , U q The voltage component in the αβ coordinate system; the voltage component is modulated by SVPWM to generate a drive signal, and the drive signal is used for grid-connected constant power control.

[0040] Specifically, in response to the energy storage converter operating in the grid-connected mode, the instantaneous voltage on the grid side is obtained; then, according to the amplitude and phase of the instantaneous voltage, the energy storage converter synchronizes the grid-side voltage to obtain the instantaneous electrical state of the common connection point, where the common connection point is the full name of Point of Common Connection, referred to as PCC, which is the intersection of more than one user or load in the power system. In the field of grid-connected renewable energy such as photovoltaic power generation, the voltage fluctuation of the common connection point is inversely proportional to the short-circuit capacity at the grid connection point. Therefore, when the photovoltaic power station is usually located at the end of a weak power grid, the voltage fluctuation will be large. Instantaneous electrical state monitoring is the basis of island detection. By real-time monitoring of electrical parameters such as voltage, current, and frequency at the common connection point, the instantaneous electrical state of the power system can be obtained. Changes in these parameters can reflect the operating status and abnormal conditions of the power system. As an example, whether an islanding effect occurs can be determined by monitoring changes in electrical parameters such as voltage and frequency at the common connection point. When the grid is disconnected, if the power provided by the distributed power source matches the power required by the load, the changes in voltage and frequency may be small and difficult to detect. In this case, a more sensitive detection method is needed. Alternatively, whether an islanding effect occurs can be determined by applying some interference signals to the grid and then monitoring the impact of these signals on the grid, including periodically changing the output current or voltage of the distributed power source and then observing whether the voltage and frequency at the common connection point change. If so, an islanding effect may have occurred.

[0041] After obtaining the instantaneous electrical state of the common connection point, the common connection point is detected for islanding according to the instantaneous electrical state to obtain the real-time state value of the reactive current. Further, according to the instantaneous electrical state, the first deviation between the voltage frequency of the common connection point and the rated frequency of the grid side is obtained; based on the preset positive feedback coefficient, the first deviation is weighted to obtain the real-time state value of the reactive current. The instantaneous electrical state can also be subjected to power factor correction or reactive compensation to monitor and adjust the reactive current in real time. For example, the reactive current can be reduced by improving the power factor, thereby improving the power quality. This is because the power factor correction device is usually composed of components such as capacitor banks or inductors, which can generate a compensation current in the opposite direction of the reactive current, which can offset the reactive current; reactive power compensation can also be generated according to the state information obtained by real-time monitoring, and reactive power demand in the power system can be balanced by compensating reactive power, and the flow of reactive current can be adjusted, thereby reducing line losses and improving voltage stability.

[0042] S102: If the real-time status value triggers the islanding effect, the current limiting operation of the energy storage converter is enabled, and based on the error adjustment of the energy storage converter, the energy storage converter is switched to operate in an off-grid mode.

[0043] In a feasible implementation manner, a second deviation between the rated capacity of the energy storage converter and the instantaneous power and load operating conditions on the grid side can be obtained; if the second deviation exceeds the preset first threshold, the real-time status value triggers the island effect, and the current loop in the energy storage converter outputs a current limiting instruction, and according to the current limiting instruction, the current limiting operation of the energy storage converter is enabled.

[0044] It should be noted that if Figure 3 As shown in the figure, the module that performs the current limiting operation is CR, i.e., the current limiting regulator. Its main function is to monitor the current in the circuit and take measures to limit it when the current exceeds the preset limit to prevent equipment damage or circuit failure. It is usually designed to automatically adjust circuit parameters such as voltage or resistance when the current is too large to keep the current within a safe range. The working principle of the current limiting regulator is based on Ohm's law (V=IR) and the basic principle of current regulation. It contains a monitoring circuit for real-time detection of the current value in the circuit. When the current exceeds the preset limit, the regulator will start and adjust the voltage or resistance in the circuit to reduce the current to a safe level. This adjustment is usually achieved through internal electronic components (such as transistors, operational amplifiers, etc.).

[0045] While performing the current limiting operation, a third deviation between the actual output voltage of the energy storage inverter and the preset reference voltage is obtained; if the third deviation exceeds the preset second threshold, the energy storage inverter is proportionally and integrally adjusted to make the actual output voltage close to the preset reference voltage, and the energy storage inverter is switched to operate in off-grid mode.

[0046] Further, Figure 4 Schematic diagram of an off-grid control strategy provided according to an embodiment of the present application. Figure 4 As shown, in off-grid mode, the energy storage converter can be equivalent to a voltage source model to perform constant voltage and constant frequency control. The voltage source model consists of a voltage outer loop and a current inner loop. The difference between constant voltage and constant frequency control and constant power control lies in the different ways of obtaining the current reference value. Among them:

[0047] The control target of the voltage outer loop is the load side voltage. The instantaneous value u of the three-phase voltage in the abc coordinate system can be obtained by voltage sampling. a 、u b 、u c Then, the instantaneous voltage value u in the dq rotating coordinate system is obtained through abc / dq transformation. d 、u q , the reference value And the instantaneous voltage value u d 、u q Compare and get the initial error; after the initial error is calculated by the PI regulator, we get Should As the given reference value of the current inner loop. According to the given initial phase, the instantaneous values ​​of the three-phase inductor current are collected. The instantaneous values ​​of the three-phase inductor current are i inv_a 、i inv_b 、i inv_c , the instantaneous current value i in the dq rotating coordinate system is obtained through abc / dq transformation d 、i q ; The instantaneous value of the current i d 、i q and Subtraction operation is performed to obtain the error value; after the error value is calculated by the PI regulator, its output value is added and subtracted from the voltage feedforward and the load term to obtain the output voltage value U d_svm , U q_svm Then, the two-phase rotating coordinate system is transformed into the two-phase stationary coordinate system (i.e., 2r / 2s) to obtain the voltage component in the αβ coordinate system; the voltage component is modulated by SVPWM to generate a drive signal, which is used for off-grid control.

[0048] It should be noted that when the energy storage converter is connected to the grid, the voltage and frequency on the grid side are clamped, and the energy storage converter operates in constant power mode. When a fault occurs in the grid, reactive current will be output to generate disturbances; according to the three-phase reactive current disturbance and frequency positive feedback control strategy, the common connection point is detected for islanding. If the islanding effect is triggered, according to the given initial phase, the voltage outer loop and current inner loop control are used to switch the energy storage converter to operate in off-grid mode.

[0049] S103: If the real-time status value does not trigger the islanding effect, the energy storage converter is maintained to operate in the grid-connected mode.

[0050] It should be noted that this embodiment is optimized from the perspective of the grid-connected control strategy. When the islanding effect is detected, the current limiting regulator enables the current limiting operation of the energy storage converter to limit the current output to ensure that the current output is stable during the transient process of switching from grid-connected to off-grid. On the other hand, in the case of erroneous switching, the current limiting regulator can also perform a reset operation to maintain the energy storage converter in the grid-connected mode. Specifically, if the real-time state value erroneously triggers the islanding effect, the current limiting operation of the energy storage converter is enabled, the switching action is reset, and the real-time state value of the reactive current is reacquired until the real-time state value jumps out of the constraint that triggers the islanding effect.

[0051] In summary, by performing island detection on the common connection point, the real-time state value of the reactive current is obtained, and the off-grid mode is identified according to the disturbance of the reactive current and the positive feedback strategy of the common connection point frequency; and by enabling the current limiting operation and error adjustment of the energy storage converter, the operation of the energy storage converter is switched from the grid-connected mode to the off-grid mode, which greatly optimizes the switching time and minimizes the power-off phenomenon of the load output voltage, and has wide applicability.

[0052] Figure 2 A schematic flow chart of another method for controlling grid-connection and off-grid connection of an energy storage converter provided in an embodiment of the present application.

[0053] like Figure 2 As shown, the energy storage converter on-grid and off-grid control method includes but is not limited to the following steps:

[0054] S201, in response to the energy storage converter operating in the grid-connected mode, obtaining the instantaneous voltage on the grid side.

[0055] For further details on step S201, please refer to the relevant contents in the above embodiment, which will not be repeated here.

[0056] S202, according to the amplitude and phase of the instantaneous voltage, the energy storage converter synchronizes the grid side voltage.

[0057] It should be noted that if an islanding effect is detected at the common connection point, step S203 is performed; if no islanding effect is detected at the common connection point, step S201 is performed.

[0058] For further details on step S202, please refer to the relevant contents in the above embodiment, which will not be repeated here.

[0059] S203, enabling the current limiting operation of the energy storage converter.

[0060] For further details on step S203, please refer to the relevant contents in the above embodiment, which will not be repeated here.

[0061] S204, based on the error adjustment of the energy storage converter, switching the energy storage converter to operate in an off-grid mode.

[0062] For further details on step S204, please refer to the relevant contents in the above embodiments, which will not be repeated here.

[0063] As an example, Figure 5 A schematic diagram of switching from on-grid to off-grid provided according to an embodiment of the present application.

[0064] like Figure 5As shown, a 500kW energy storage converter system is built using Matlab / Simulink. The load adopts a 60% resistive inductive load with a rated capacity of 500kVA and a power factor of 0.8. According to the energy storage converter on-grid and off-grid control method provided in this embodiment, on-grid to off-grid switching is performed. It can be seen that in the on-grid mode, the energy storage converter discharges 500kW to the grid. At this time, the current on the grid side removes the active power loss of the load and also includes the reactive current provided by the grid to the load; at 0.28s, the grid loses power, and the three-phase current on the grid side is instantly 0. The power of the energy storage converter is converted from the on-grid 500kW to the off-grid load 300kVA. The output current of the energy storage converter itself is reduced, and the load current remains basically stable, completing the seamless switching from on-grid to off-grid.

[0065] Figure 6 Another schematic diagram of switching from grid-connected to off-grid provided according to an embodiment of the present application.

[0066] like Figure 6 As shown, a 500kW energy storage converter system is built using Matlab / Simulink. The load adopts a 100% resistive inductive load with a rated capacity of 500kVA and a power factor of 0.8. According to the energy storage converter on-grid and off-grid control method provided in this embodiment, on-grid to off-grid switching is performed. It can be seen that in the on-grid mode, the energy storage converter still discharges 500kW to the grid. At 0.28s, the grid loses power, and the three-phase current on the grid side is instantly 0. The power of the energy storage converter is converted from the on-grid 500kW to the off-grid load 500kVA. The output current of the energy storage converter itself remains unchanged, and the load current remains basically stable, completing the seamless switching from on-grid to off-grid.

[0067] In summary, by performing island detection on the common connection point, the real-time state value of the reactive current is obtained, and the off-grid mode is identified according to the disturbance of the reactive current and the positive feedback strategy of the common connection point frequency; and by enabling the current limiting operation and error adjustment of the energy storage converter, the operation of the energy storage converter is switched from the grid-connected mode to the off-grid mode, which greatly optimizes the switching time and minimizes the power-off phenomenon of the load output voltage, and has wide applicability.

[0068] Figure 7 This is a schematic diagram of the structure of an energy storage converter on-grid and off-grid control device provided in an embodiment of the present application. Figure 7 As shown, the energy storage converter on-grid and off-grid control device 700 includes:

[0069] An acquisition module 701, in response to the energy storage converter operating in the grid-connected mode, performs island detection on the common connection point according to the synchronized grid-side voltage to acquire the real-time state value of the reactive current, wherein the common connection point is set at the connection position between the grid side and the energy storage converter;

[0070] A first regulating module 702, the first regulating module 702 is used to trigger the islanding effect in the real-time state value, enable the current limiting operation of the energy storage converter, and switch the energy storage converter to operate in an off-grid mode based on the error regulation of the energy storage converter;

[0071] The second regulating module 703 is used to maintain the energy storage converter operating in the grid-connected mode when the real-time state value does not trigger the islanding effect.

[0072] Figure 8 The present invention is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present application. Figure 8 The electronic device shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0073] like Figure 8 As shown, the electronic device 800 includes a processor 801, which can perform various appropriate actions and processes according to the program stored in the read-only memory (ROM) 802 or the program loaded from the memory 1006 to the random access memory (RAM) 803. In the RAM 803, various programs and data required for the operation of the electronic device 800 are also stored. The processor 801, ROM 802 and RAM 803 are connected to each other through a bus 804. An input / output (I / O) interface 805 is also connected to the bus 804.

[0074] The following components are connected to the I / O interface 805: a memory 806 including a hard disk, etc.; and a communication part 807 including a network interface card such as a LAN (Local Area Network) card, a modem, etc., and the communication part 807 performs communication processing via a network such as the Internet; a drive 808 is also connected to the I / O interface 805 as needed.

[0075] In particular, according to an embodiment of the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present application includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 807. When the computer program is executed by the processor 801, the above-mentioned functions defined in the method of the present application are executed.

[0076] In an exemplary embodiment, a storage medium including instructions is also provided, such as a memory including instructions, and the instructions can be executed by the processor 801 of the electronic device 800 to complete the above method. Optionally, the storage medium can be a non-transitory computer-readable storage medium, for example, the non-transitory computer-readable storage medium can be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

[0077] In the present application, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in combination with an instruction execution system, apparatus, or device. In the present application, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries a computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in combination with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium may be transmitted using any suitable medium, including but not limited to: wireless, wire, optical cable, RF, etc., or any suitable combination of the above.

[0078] Fig. 9 The figure is a schematic diagram of the structure of another electronic device provided according to an embodiment of the present application. Fig. 9 The electronic device shown is only an example and should not limit the functions and scope of use of the embodiments of the present application. Fig. 9 As shown, the electronic device 900 includes a processor 901 and a memory 902. The memory 902 is used to store program codes, and the processor 901 is connected to the memory 902 to read the program codes from the memory 902 to implement the energy storage converter on-grid and off-grid control method in the above embodiment.

[0079] Optionally, the number of processors 901 may be one or more.

[0080] Optionally, the electronic device may further include an interface 903, and the number of the interface 903 may be multiple. The interface 903 may be connected to an application program and may receive data from an external device such as a sensor.

[0081] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed in this application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0082] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for controlling an energy storage converter on and off the grid, characterized in that: include: In response to the energy storage converter operating in the grid-connected mode, an island detection is performed on the common connection point according to the synchronized grid-side voltage to obtain a real-time state value of the reactive current, wherein the common connection point is set at a connection position between the grid side and the energy storage converter; If the real-time status value triggers an islanding effect, enabling a current limiting operation of the energy storage converter, and switching the energy storage converter to operate in an off-grid mode based on an error adjustment of the energy storage converter; If the real-time status value does not trigger an islanding effect, the energy storage converter is maintained to operate in a grid-connected mode.

2. The method according to claim 1, characterized in that In response to the energy storage converter operating in the grid-connected mode, performing island detection on the common connection point according to the synchronized grid-side voltage to obtain the real-time state value of the reactive current includes: In response to the energy storage converter operating in the grid-connected mode, obtaining an instantaneous voltage on the grid side; According to the amplitude and phase of the instantaneous voltage, the energy storage converter synchronizes the grid-side voltage to obtain the instantaneous electrical state of the common connection point; According to the instantaneous electrical state, island detection is performed on the common connection point to obtain a real-time state value of reactive current.

3. The method according to claim 2, characterized in that The performing island detection on the common connection point according to the instantaneous electrical state to obtain the real-time state value of reactive current includes: Acquire a first deviation between the voltage frequency of the common connection point and the rated frequency of the grid side according to the instantaneous electrical state; Based on a preset positive feedback coefficient, the first deviation is weighted to obtain a real-time state value of the reactive current.

4. The method according to claim 1, characterized in that: If the real-time status value triggers an islanding effect, enabling a current limiting operation of the energy storage converter includes: Obtaining a second deviation between the rated capacity of the energy storage converter and the instantaneous power and load operating conditions on the grid side; If the second deviation exceeds the preset first threshold, the real-time status value triggers the islanding effect, the current loop in the energy storage converter outputs a current limiting instruction, and according to the current limiting instruction, the current limiting operation of the energy storage converter is enabled.

5. The method according to claim 1, characterized in that: The step of switching the energy storage converter to operate in an off-grid mode based on the error adjustment of the energy storage converter includes: Obtaining a third deviation between an actual output voltage of the energy storage converter and a preset reference voltage; If the third deviation exceeds the preset second threshold, proportional-integral adjustment is performed on the energy storage converter to make the actual output voltage close to the preset reference voltage, and the energy storage converter is switched to operate in an off-grid mode.

6. The method according to any one of claims 1 to 5, characterized in that The method further comprises: If the real-time status value erroneously triggers the islanding effect, the current limiting operation of the energy storage converter is enabled, the switching action is reset, and the real-time status value of the reactive current is reacquired until the real-time status value jumps out of the constraint that triggers the islanding effect.

7. A grid-connected and off-grid control device for an energy storage converter, characterized in that: include: An acquisition module, wherein in response to the energy storage converter operating in the grid-connected mode, the acquisition module performs island detection on the common connection point according to the synchronized grid-side voltage to acquire the real-time state value of the reactive current, wherein the common connection point is set at the connection position between the grid side and the energy storage converter; A first regulating module, wherein the first regulating module is used to trigger an islanding effect at the real-time state value, enable a current limiting operation of the energy storage converter, and switch the energy storage converter to operate in an off-grid mode based on an error regulation of the energy storage converter; The second regulating module is used for maintaining the energy storage converter to operate in a grid-connected mode when the real-time state value does not trigger an islanding effect.

8. An electronic device, characterized in that: include: processor; a memory for storing instructions executable by the processor; The processor is configured to execute the instructions to implement the method according to any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium, characterized in that: When the instructions in the storage medium are executed by a processor of an electronic device, the electronic device is enabled to execute the method as claimed in any one of claims 1 to 6.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the method according to any one of claims 1 to 6 when being executed by a processor.

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