Control method of off-grid energy storage device and off-grid energy storage device

Abstract

The invention provides a control method of an off-grid energy storage device and the off-grid energy storage device. The control method comprises the following steps: collecting power grid voltage state data of a power grid; when it is judged that the power grid voltage state data meet the pre-configured mode switching condition, the amplitude and phase of the power grid voltage in the power grid voltage state data are obtained; the mode switching conditions comprise an energy storage-power grid switching condition for switching from battery pack power supply to power grid power supply and a power grid-energy storage switching condition for switching from power grid power supply to battery pack power supply; and the control module is used for controlling the mode change-over switch circuit to perform corresponding switching on the basis of a mode switching condition conforming to the state data of the power grid voltage, and controlling the amplitude and the phase of the inverter voltage output by the bidirectional AC / DC conversion module on the basis of the amplitude and the phase of the power grid voltage. The amplitude and the phase of the load voltage received by the load before and after mode switching are in a continuous state, so that the switching time is shortened, and the power failure risk of a user is reduced.

Description

Technical Field

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

[0002] With the advent of energy storage in ordinary households, users can achieve distributed power generation by installing household energy storage products, relieve the power transmission pressure of the power grid, reduce electricity bills, and more importantly, eliminate the adverse effects of power outages on normal life. In the case of normal grid operation, the off-grid household energy storage device converts alternating current (AC) to direct current (DC) through the energy storage device to charge the battery and supply power to household loads at the same time.

[0003] When the energy storage device detects an abnormal mains voltage, it stops the AC / DC conversion and reversely converts the direct current (DC) of the battery into alternating current (AC) to supply power to the user load; when the energy storage device detects that the mains voltage has returned to normal, the energy storage device stops supplying power to the load, and then the mains continues to supply power to the load. At the same time, the energy storage device changes the direction of energy flow and again converts from AC to DC, and the mains charges the battery.

[0004] In the above scenario, when the mains is abnormal, the energy storage device switches from charging the battery to inverting to supply power to the load. The traditional conversion method of the energy storage device needs to stop the AC / DC wave after the AC / DC is shut down and then switch to DC / AC. When the mains is normal, it is also necessary to turn off the energy storage device, close the relay, and charge the battery while supplying power to the load; therefore, there is a risk of load power loss whether the mains is abnormal or the mains returns to normal. The longest switching time can reach 30 ms, and the shortest switching time is also greater than 10 ms. The power supply interruption will have an adverse impact on the customer load and reduce the customer experience. Summary of the Invention

[0005] In view of this, the purpose of the present application is to provide a control method and device for an off-grid energy storage device, which can greatly shorten the switching duration of the power supply between the mains and the energy storage device and reduce the risk of user power loss.

[0006] A control method for an off-grid energy storage device provided by an embodiment of the present application is applied to a controller of the off-grid energy storage device; the off-grid energy storage device further includes a bidirectional AC / DC conversion module, a battery pack, and a mode switching switch circuit; the mode switching switch circuit is used to supply power to the load through the switching switch state by the power grid or supply power to the load by the battery pack through the AC / DC conversion module and the switching switch circuit;

[0007] The control method includes:

[0008] Collect grid voltage status data of the power grid;

[0009] When it is determined that the grid voltage status data meets the pre-configured mode switching conditions, obtain the amplitude and phase of the grid voltage in the grid voltage status data; the mode switching conditions include the energy storage-grid switching condition for switching from battery pack power supply to grid power supply and the grid-energy storage switching condition for switching from grid power supply to battery pack power supply.

[0010] Based on the mode switching conditions that the grid voltage status data meets, control the mode switching switch circuit to perform corresponding switching, and based on the amplitude and phase of the grid voltage, control the amplitude and phase of the inverted voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the load voltage received by the load before and after the mode switching are in a continuous state.

[0011] In some embodiments, in the control method of the off-grid energy storage device, the energy storage-grid switching condition includes at least one of the following: the grid returns to normal from a fault state, reaches a preset energy storage-grid switching time point, and receives an energy storage-grid switching signal.

[0012] The grid-energy storage switching condition includes: the grid is in a fault state, reaches a preset grid-energy storage switching time point, and receives a grid-energy storage switching signal.

[0013] Wherein, the fault state includes at least one of the following: overvoltage, undervoltage, underfrequency, overfrequency, and the power-off speed is greater than a preset power-off speed threshold.

[0014] In some embodiments, in the control method of the off-grid energy storage device, before determining that the grid voltage status data meets the pre-configured mode switching conditions, the method further includes:

[0015] When in the grid power supply mode, based on the grid voltage status data, determine whether the grid is in a fault state.

[0016] If so, determine that the grid voltage status data meets the grid-energy storage switching conditions.

[0017] Or,

[0018] When in the battery pack power supply mode, based on the grid voltage status data, determine whether the grid has returned to normal from a fault state.

[0019] If so, determine that the grid voltage status data meets the pre-configured energy storage-grid switching conditions.

[0020] In some embodiments, in the control method of the off-grid energy storage device, based on the mode switching conditions met by the grid voltage state data, the mode switching switch circuit is controlled to perform corresponding switching, and based on the amplitude and phase of the grid voltage, the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module are controlled so that the amplitude and phase of the load voltage input to the load before and after mode switching are in a continuous state, including:

[0021] When it is determined that the grid voltage state data meets the grid - energy storage switching condition, the mode switching switch circuit is controlled to switch from grid power supply to battery pack power supply;

[0022] Based on the amplitude and phase of the grid voltage, a first inverter signal is generated; the first inverter signal is used to modulate the amplitude and phase of the first inverter voltage output by the bidirectional AC / DC conversion module so that the amplitude and phase of the first inverter voltage and the first grid voltage are the same;

[0023] The first inverter signal is sent to the bidirectional AC / DC conversion module so that the bidirectional AC / DC conversion module outputs a first inverter voltage based on the first inverter signal.

[0024] In some embodiments, in the control method of the off-grid energy storage device, based on the mode switching conditions met by the grid voltage state data, the mode switching switch circuit is controlled to perform corresponding switching, and based on the amplitude and phase of the grid voltage, the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module are controlled so that the amplitude and phase of the load voltage input to the load before and after mode switching are in a continuous state, including:

[0025] When it is determined that the grid voltage state data meets the energy storage - grid switching condition, the amplitude and phase of the grid voltage are obtained;

[0026] Based on the amplitude and phase of the second grid voltage of the grid in power supply, a second inverter signal is generated; the second inverter signal is used to modulate the amplitude and phase of the second inverter voltage output by the bidirectional AC / DC conversion module;

[0027] The second inverter signal is sent to the bidirectional AC / DC conversion module so that the bidirectional AC / DC conversion module outputs an inverter voltage based on the second inverter signal;

[0028] When the amplitude and phase of the second inverter voltage and the grid voltage are the same, the mode switching switch circuit is controlled to switch from battery pack power supply to grid power supply.

[0029] In some embodiments, in the control method of the off-grid energy storage device, based on the amplitude and phase of the grid voltage, the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module are controlled, including:

[0030] Collect the actual inverter voltage output by the bidirectional AC / DC conversion module, the actual output current, and the actual inductor current of the bidirectional AC / DC conversion module;

[0031] Based on the amplitude and phase of the grid voltage, the actual inverter voltage, the actual output current, and the actual inductor current, control the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module, and the magnitude of the actual output current.

[0032] In some embodiments, in the control method of the off-grid energy storage device, based on the amplitude and phase of the grid voltage, the actual inverter voltage, the actual output current, and the actual inductor current, control the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module, and the magnitude of the output inverter current, including:

[0033] Generate a first modulation quantity for controlling the amplitude and phase of the inverter voltage based on the amplitude and phase of the grid voltage and the actual inverter voltage output by the bidirectional AC / DC conversion module;

[0034] Based on the actual output current output by the bidirectional AC / DC conversion module and the actual inductor current of the bidirectional AC / DC conversion module, re-modulate the first modulation quantity to generate a second modulation quantity for further controlling the magnitude of the actual output current of the bidirectional AC / DC conversion module;

[0035] Output the second modulation quantity to the bidirectional AC / DC conversion module to control the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module and the magnitude of the actual output current.

[0036] In some embodiments, in the control method of the off-grid energy storage device, generating a first modulation quantity for controlling the amplitude and phase of the inverter voltage based on the amplitude and phase of the grid voltage and the actual inverter voltage output by the bidirectional AC / DC conversion module includes:

[0037] Determine the voltage loop reference of the voltage loop in the controller based on the amplitude and phase of the grid voltage, and use the actual inverter voltage as the voltage loop feedback;

[0038] Adjust the voltage loop based on the voltage loop reference and the voltage loop feedback to generate a first modulation quantity for controlling the amplitude and phase of the first inverter voltage.

[0039] In some embodiments, in the control method of the off-grid energy storage device, re-modulating the first modulation quantity based on the actual output current output by the bidirectional AC / DC conversion module and the actual inductor current of the bidirectional AC / DC conversion module to generate a second modulation quantity for further controlling the magnitude of the actual output current of the bidirectional AC / DC conversion module includes:

[0040] Take the first modulation quantity output by the voltage loop as the current loop reference of the current loop in the controller, and take the actual output current and actual inductor current of the bidirectional AC / DC conversion module as the current loop feedback;

[0041] Based on the current loop reference and current loop feedback, adjust the current loop to generate a second modulation quantity that is also used to control the magnitude of the actual output current of the bidirectional AC / DC conversion module.

[0042] In some embodiments, in the control method of the off-grid energy storage device, the phase of the grid voltage is acquired based on the phase-locked loop in the controller.

[0043] In some embodiments, in the control method of the off-grid energy storage device, determining the voltage loop reference of the voltage loop in the controller based on the amplitude and phase of the grid voltage includes:

[0044] Multiply the amplitude of the grid voltage by the phase to obtain the voltage loop reference of the voltage loop in the controller.

[0045] In some embodiments, in the control method of the off-grid energy storage device, the mode switching switch circuit includes: a first switch and a second switch; the first switch and the second switch are connected in series;

[0046] The external connection end of the first switch is connected to the grid, and the external connection end of the second switch is connected to the load;

[0047] The series connection end of the first switch and the second switch is connected to the output end of the bidirectional AC / DC conversion module.

[0048] In some embodiments, there is also provided an off-grid energy storage device, including a controller, a bidirectional AC / DC conversion module, a battery pack, and a mode switching switch circuit;

[0049] The mode switching switch circuit is used to supply power to the load through the switching switch circuit by the grid or supply power to the load by the battery pack through the AC / DC conversion module and the switching switch circuit by switching the switch state;

[0050] The controller is used to collect the grid voltage state data of the grid;

[0051] When it is determined that the grid voltage state data meets the pre-configured mode switching conditions, obtain the amplitude and phase of the grid voltage in the grid voltage state data; the mode switching conditions include the energy storage-grid switching conditions for switching from battery pack power supply to grid power supply and the grid-energy storage switching conditions for switching from grid power supply to battery pack power supply;

[0052] Based on the mode switching condition met by the grid voltage status data, control the mode switching switch circuit to perform corresponding switching, and based on the amplitude and phase of the grid voltage, control the amplitude and phase of the inverted voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the load voltage received by the load before and after mode switching are in a continuous state.

[0053] In an embodiment of the present application, a control method for an off-grid energy storage device and an off-grid energy storage device are provided. The method is applied to a controller of the off-grid energy storage device; the off-grid energy storage device further includes a bidirectional AC / DC conversion module, a battery pack, and a mode switching switch circuit; the mode switching switch circuit is used to supply power to the load through the switching switch state by the grid or to supply power to the load by the battery pack through the AC / DC conversion module and the switching switch circuit; the control method includes: collecting grid voltage status data of the grid; when it is determined that the grid voltage status data meets a pre-configured mode switching condition, obtaining the amplitude and phase of the grid voltage in the grid voltage status data; the mode switching condition includes an energy storage-grid switching condition for switching from battery pack power supply to grid power supply and a grid-energy storage switching condition for switching from grid power supply to battery pack power supply; based on the mode switching condition met by the grid voltage status data, control the mode switching switch circuit to perform corresponding switching, and based on the amplitude and phase of the grid voltage, control the amplitude and phase of the inverted voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the load voltage received by the load before and after mode switching are in a continuous state; in this way, it is not necessary to turn off the energy storage device, but by adjusting and controlling the inverted signal of the inverted voltage output by the energy storage device, the amplitude and phase of the inverted voltage output by the energy storage device are made consistent with those of the grid voltage, thereby realizing the rapid switching of power supply to the load by the grid and the energy storage device, reducing the switching time, and reducing the power-off risk of users. Brief Description of the Drawings

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0055] Figure 1 Shows the circuit schematic diagram of an off-grid energy storage device described in an embodiment of the present application;

[0056] Figure 2 Shows the waveform diagram of the load voltage received by the load when the energy storage device and the grid are switched in the traditional manner in the embodiment of the present application;

[0057] Figure 3The method flow chart of the control method of the off-grid energy storage device described in the embodiments of the present application is shown;

[0058] Figure 4 The method flow chart of the control mode switching switch circuit switching from grid power supply to battery pack power supply in the embodiments of the present application is shown;

[0059] Figure 5 The method flow chart of the control mode switching switch circuit switching from battery pack power supply to grid power supply in the embodiments of the present application is shown;

[0060] Figure 6 The method flow chart of controlling the amplitude and phase of the inverter voltage output by the control bidirectional AC / DC conversion module in the embodiments of the present application is shown;

[0061] Figure 7 The control schematic diagram of the controller described in the embodiments of the present application is shown;

[0062] Figure 8 The waveform diagram of the load voltage received by the load when the energy storage device and the grid are switched according to the control method in the embodiments of the present application is shown. Detailed implementation manners

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. It should be understood that the accompanying drawings in the present application only serve the purpose of illustration and description, and are not used to limit the protection scope of the present application. In addition, it should be understood that the schematic drawings are not drawn to actual scale. The flowcharts used in the present application show the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart may not be implemented in sequence, and steps without logical context relationships may be reversed or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart or remove one or more operations from the flowchart under the guidance of the content of the present application.

[0064] As energy storage enters ordinary families, users can realize the concept of distributed power generation, relieve the grid transmission pressure, reduce electricity bills, and more importantly, eliminate the adverse effects of power outages on normal life by installing household energy storage products.

[0065] Please refer to Figure 1 , Figure 1 shows the circuit schematic diagram of an off-grid energy storage device described in the embodiments of the present application; when the grid 101 is normal, the off-grid household energy storage device 103 closes the first relay Rly1 and the second relay Rly2, and the grid 101 converts alternating current AC into direct current DC through the energy storage device 103 to charge the battery and supply power to the household load 102 at the same time;

[0066] When the energy storage device 103 detects an abnormal voltage of the power grid 101, it disconnects the first relay Rly1 and the second relay Rly2. The energy storage device 103 stops the AC-DC conversion, reversely converts the direct current DC of the battery into alternating current AC, then closes the second relay Rly2, and supplies power to the user load 102;

[0067] When the energy storage device 103 detects that the voltage of the power grid 101 has returned to normal, the energy storage device 103 stops supplying power to the load 102, and then closes the first relay Rly1. At this time, the power grid 101 continues to supply power to the load 102. At the same time, the energy storage device 103 changes the energy flow direction, and again from AC to DC, and the power grid 101 charges the battery;

[0068] In the above scenario, when the power grid 101 is abnormal, the energy storage device 103 switches from charging the battery to inverting and supplying power to the load 102, experiencing relay on / off. The traditional conversion method of the energy storage device 103 needs to be converted to DC-AC after the AC-DC wave is blocked and shut down. When the power grid 101 is normal, it is also necessary to turn off the energy storage device 103, close the relay, and charge the battery while supplying power to the load 102; Therefore, there is a risk of power loss of the load 102 whether the power grid 101 is abnormal or the power grid 101 returns to normal. The longest switching time can reach 30 ms, and the minimum switching time is also greater than 10 ms. The power supply interruption will have an adverse impact on the customer load 102 and reduce the customer experience.

[0069] Please refer to Figure 2 , Figure 2 which shows the waveform diagram of the load voltage received by the load when the energy storage device and the power grid described in the embodiment of the present application are switched.

[0070] Based on this, an embodiment of the present application provides a control method for an off-grid energy storage device and an off-grid energy storage device. The method is applied to a controller of the off-grid energy storage device. The off-grid energy storage device further includes a bidirectional AC / DC conversion module, a battery pack, and a mode switching switch circuit. The mode switching switch circuit is configured to supply power to a load through the switching switch state, either by enabling the power grid to supply power to the load through the switching switch circuit or by enabling the battery pack to supply power to the load through the AC / DC conversion module and the switching switch circuit. The control method includes: collecting grid voltage state data of the power grid; when it is determined that the grid voltage state data meets a pre-configured mode switching condition, obtaining the amplitude and phase of the grid voltage in the grid voltage state data. The mode switching conditions include an energy storage-grid switching condition for switching from battery pack power supply to grid power supply and a grid-energy storage switching condition for switching from grid power supply to battery pack power supply; based on the mode switching condition that the grid voltage state data meets, controlling the mode switching switch circuit to perform corresponding switching, and based on the amplitude and phase of the grid voltage, controlling the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the load voltage received by the load before and after mode switching are in a continuous state. In this way, it is not necessary to turn off the energy storage device. Instead, by adjusting and controlling the inverter signal of the inverter voltage output by the energy storage device, the amplitude and phase of the inverter voltage output by the energy storage device are made consistent with those of the grid voltage, thereby realizing a fast switch between the power grid and the energy storage device for supplying power to the load, reducing the switching time, and reducing the power-off risk of users.

[0071] Please refer to Figure 3 , Figure 3 shows a flowchart of the control method for the off-grid energy storage device according to an embodiment of the present application. The control method is applied to a controller of the off-grid energy storage device. The off-grid energy storage device further includes a bidirectional AC / DC conversion module, a battery pack, and a mode switching switch circuit. The mode switching switch circuit is configured to supply power to a load through the switching switch state, either by enabling the power grid to supply power to the load through the switching switch circuit or by enabling the battery pack to supply power to the load through the AC / DC conversion module and the switching switch circuit. Please refer to Figure 3 , the method includes the following steps S301 - S303:

[0072] S301. Collect grid voltage state data of the power grid;

[0073] S302. When it is determined that the grid voltage state data meets a pre-configured mode switching condition, obtain the amplitude and phase of the grid voltage in the grid voltage state data. The mode switching conditions include an energy storage-grid switching condition for switching from battery pack power supply to grid power supply and a grid-energy storage switching condition for switching from grid power supply to battery pack power supply;

[0074] S303. Based on the mode switching conditions that conform to the grid voltage status data, control the mode switching switch circuit to perform corresponding switching, and based on the amplitude and phase of the grid voltage, control the amplitude and phase of the inverted voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the load voltage received by the load before and after mode switching are in a continuous state.

[0075] Please refer to Figure 1 , the mode switching switch circuit includes: a first switch and a second switch; the first switch and the second switch are connected in series;

[0076] The external connection end of the first switch is connected to the power grid, and the external connection end of the second switch is connected to the load;

[0077] The series connection end of the first switch and the second switch is connected to the output end of the bidirectional AC / DC conversion module.

[0078] Specifically, the first switch is the first relay Rly1, and the second switch is the second relay Rly2.

[0079] In the step S101, collect the grid voltage status data of the power grid.

[0080] Specifically, the grid voltage status data characterizes the operating state and power quality of the power grid. The grid voltage status data includes: voltage amplitude, voltage waveform, voltage phase, voltage frequency, power-off speed, current value, etc.

[0081] The voltage amplitude refers to the amplitude of the grid voltage. The change of the voltage amplitude will affect the stability of the power system and the power quality. In the embodiments of the present application, the voltage amplitude is collected based on the power monitoring system.

[0082] The voltage waveform refers to the curve of the grid voltage changing with time. The voltage waveform can reflect information such as the harmonic components, fluctuation magnitude, and stability of the grid voltage.

[0083] The voltage phase refers to the relationship between the grid voltage and time, that is, the phase angle of the voltage. The change of the voltage phase will affect the power factor and efficiency of the power system.

[0084] The voltage frequency refers to the number of periodic changes per unit time in the voltage signal, and the unit is Hertz (Hz), that is, the number of cycles repeated per second. In an AC power system, the voltage frequency is usually 50 Hertz or 60 Hertz.

[0085] The power-off speed of the power grid refers to the speed at which the power supply is interrupted when a fault occurs in the power grid.

[0086] The voltage value of the power grid refers to the effective value of the grid voltage.

[0087] Specifically, in actual applications, the grid voltage status data can be collected through the following methods:

[0088] Using a voltage transformer: A voltage transformer is an instrument used to measure AC voltage. It can convert the grid voltage into a lower voltage and measure the magnitude and waveform of this voltage.

[0089] Using a power monitoring system: A power monitoring system is a system that integrates multiple power meters and sensors. It can monitor parameters such as the voltage, current, and frequency of the grid in real time, and record and analyze these data. By using a power monitoring system, the status data of the grid voltage can be conveniently obtained.

[0090] Using a smart meter: A smart meter is a meter with automatic measurement and recording functions. It can monitor parameters such as the voltage, current, and active power of the grid in real time and record these data.

[0091] The collected original voltage status data needs to be processed and analyzed to extract the useful grid voltage status data required by the embodiments of the present application. Processing and analyzing the original voltage status data includes steps such as data cleaning, feature extraction, and anomaly detection to obtain the status information of the grid voltage.

[0092] By using these collection devices to collect the original voltage status data, after processing the original voltage status data, the grid voltage status data required by the controller of the present application is obtained, and the grid voltage status data is sent to the controller so that the controller can collect the grid voltage status data.

[0093] In the embodiments of the present application, the grid voltage status data of the grid is collected to monitor the grid voltage status in real time.

[0094] Specifically, in the embodiments of the present application, the phase of the grid voltage is collected based on the phase-locked loop in the controller.

[0095] In step S102, when it is determined that the grid voltage status data meets the pre-configured mode switching conditions, the amplitude and phase of the grid voltage in the grid voltage status data are obtained; the mode switching conditions include the energy storage-grid switching conditions for switching from battery pack power supply to grid power supply and the grid-energy storage switching conditions for switching from grid power supply to battery pack power supply.

[0096] The energy storage-grid switching conditions include at least one of the following: the grid resumes normal from a fault state, reaches a preset energy storage-grid switching time point, and receives an energy storage-grid switching signal;

[0097] The grid-energy storage switching conditions include: the grid is in a fault state, reaches a preset grid-energy storage switching time point, and receives a grid-energy storage switching signal;

[0098] Among them, the fault state at least includes one of the following: overvoltage, undervoltage, underfrequency, overfrequency, and the power-off speed is greater than a preset power-off speed threshold.

[0099] Overvoltage: It means that the grid voltage value exceeds the preset normal voltage range, which may be caused by reasons such as transmission line overload and transformer failure. Overvoltage will cause problems such as equipment damage and insulation failure, and may even cause fires.

[0100] Undervoltage: It means that the grid voltage value is lower than the preset normal voltage range, which may be caused by reasons such as line loss and excessive load. Undervoltage will cause the equipment to fail to operate normally or even be damaged, and will also affect the stability and reliability of the power system.

[0101] Underfrequency: It means that the grid frequency is lower than the preset normal frequency range, which may be caused by reasons such as generator failure and load change. Underfrequency will cause problems such as unstable operation and vibration of the motor, affecting the normal operation of the power system.

[0102] Overfrequency: It means that the grid frequency exceeds the preset normal frequency range, which may be caused by reasons such as sudden reduction of load and generator failure. Overfrequency will cause problems such as equipment damage and insulation failure, affecting the stability and reliability of the power system.

[0103] The power-off speed is greater than the preset power-off speed threshold, that is, the power-off speed of the grid is too fast.

[0104] Specifically, for each fault state, corresponding fault judgment conditions are configured, and based on whether the grid voltage state data of the corresponding type meets the fault judgment conditions, it is determined whether the grid voltage is in the fault state.

[0105] The grid has a fault state, that is, when the grid is in a normal state, at least one fault state occurs.

[0106] The grid recovers from the fault state to normal, that is, when the grid is in at least one fault state, it recovers to the normal state.

[0107] Among the energy storage-grid switching conditions, reaching the preset energy storage-grid switching time point is a control method of timed switching. For example, during the low-power consumption period at 1 o'clock in the morning every day, the power supply is switched from the battery pack to the grid.

[0108] Among the energy storage-grid switching conditions, receiving an energy storage-grid switching signal is only an example and can be a manual switch. The user can manually input a control signal to close the first relay Rly1.

[0109] Among the grid - energy storage switching conditions, reaching the preset grid - energy storage switching time point is a control method of timed switching. For example, during the peak electricity consumption period at 8 pm every night, switch from grid power supply to battery pack power supply. Or in the forced discharge mode, the user actively sets the switching time, and the energy storage system automatically switches.

[0110] Among the grid - energy storage switching conditions, receiving the grid - energy storage switching signal. Only as an example, it can be a manual switch, where a control signal can be manually input to turn on the first relay Rly1. The following mainly discusses real - time tracking of the phase and amplitude of the grid voltage, detecting abnormal grid states, and smooth switching during the charging and discharging process to reduce the power - off time of the load. Specifically, it includes two cases. When the grid is in normal power supply, if it is detected that the grid has an abnormal state, then switch from grid power supply to battery pack power supply. After that, continue to track and monitor the grid. When it is detected that the grid returns to normal from the fault state, then switch from battery pack power supply to grid power supply.

[0111] The grid power supply can also be called the mains power supply, that is, the grid supplies power to the load through the switching switch circuit.

[0112] The battery pack power supply can also be called the energy storage device power supply, that is, the battery pack supplies power to the load through the AC / DC conversion module and the switching switch circuit.

[0113] In step S103, based on the mode - switching conditions met by the grid voltage state data, control the mode - switching switch circuit to perform corresponding switching, and based on the amplitude and phase of the grid voltage, control the amplitude and phase of the inverted voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the load voltage received by the load before and after the mode - switching are in a continuous state.

[0114] Based on this, there are two cases for controlling the mode - switching switch circuit to perform corresponding switching in step S103: controlling the mode - switching switch circuit to switch from grid power supply to battery pack power supply, or controlling the mode - switching switch circuit to switch from battery pack power supply to grid power supply.

[0115] Specifically, please refer to Figure 4 , Figure 4 shows the method flow chart for controlling the mode - switching switch circuit to switch from grid power supply to battery pack power supply in the embodiment of the present application; as Figure 4 shown, based on the mode - switching conditions met by the grid voltage state data, control the mode - switching switch circuit to perform corresponding switching, and based on the amplitude and phase of the grid voltage, control the amplitude and phase of the inverted voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the load voltage input to the load before and after the mode - switching are in a continuous state, including the following steps S401 - S403:

[0116] S401. When it is determined that the grid voltage status data meets the grid - energy storage switching condition, control the mode - switching switch circuit to switch from grid power supply to battery - pack power supply;

[0117] S402. Generate a first inversion signal based on the amplitude and phase of the grid voltage; the first inversion signal is used to modulate the amplitude and phase of the first inversion voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the first inversion voltage are the same as those of the first grid voltage;

[0118] S403. Send the first inversion signal to the bidirectional AC / DC conversion module, so that the bidirectional AC / DC conversion module outputs a first inversion voltage based on the first inversion signal.

[0119] Specifically, when the mode - switching switch circuit switches from grid power supply to battery - pack power supply, that is, disconnect the first relay Rly1.

[0120] Please refer to Figure 5 , Figure 5 which shows the flowchart of the method for the mode - switching switch circuit of the embodiment of the present application to switch from battery - pack power supply to grid power supply; as Figure 5 shown, based on the mode - switching condition met by the grid voltage status data, control the mode - switching switch circuit to perform corresponding switching, and based on the amplitude and phase of the grid voltage, control the amplitude and phase of the inversion voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the load voltage input to the load before and after the mode - switching are in a continuous state, including the following steps S501 - S504:

[0121] S501. When it is determined that the grid voltage status data meets the energy storage - grid switching condition, obtain the amplitude and phase of the grid voltage;

[0122] S502. Generate a second inversion signal based on the amplitude and phase of the second grid voltage of the grid in power supply; the second inversion signal is used to modulate the amplitude and phase of the second inversion voltage output by the bidirectional AC / DC conversion module;

[0123] S503. Send the second inversion signal to the bidirectional AC / DC conversion module, so that the bidirectional AC / DC conversion module outputs an inversion voltage based on the second inversion signal;

[0124] S504. When the amplitude and phase of the second inversion voltage are the same as those of the grid voltage, control the mode - switching switch circuit to switch from battery - pack power supply to grid power supply.

[0125] Specifically, when the mode - switching switch circuit switches from battery - pack power supply to grid power supply, that is, close the first relay Rly1.

[0126] When switching from grid power supply to battery pack power supply, the first relay Rly1 is directly output, and based on making the phase and amplitude of the first inverted voltage output by modulating the two-way AC / DC conversion module consistent with the voltage amplitude and phase during grid power failure, seamless switching from grid power supply to battery pack power supply is achieved.

[0127] When switching from battery pack power supply to grid power supply, it is necessary to first track the amplitude and phase of the grid voltage, and output a second inverted signal to modulate the second inverted voltage output by the two-way AC / DC conversion module, so that after the phase and amplitude of the second inverted voltage are consistent with the amplitude and phase of the grid voltage, then turn off the first relay Rly1 to switch the battery pack power supply to grid power supply.

[0128] In this way, by real-time tracking the grid voltage status information, combining the working state switching of the off-line energy storage device and the control algorithm during the switching process, when the mains power is abnormal, the switching time of the energy storage device from ACDC to DCAC and then back to ACDC after the mains power returns to normal can be greatly shortened, so as to ensure uninterrupted power supply to the load and improve the user experience.

[0129] During the power supply switching process, the load current may be temporarily too large because during the switching process, the load needs to switch from the old power supply to the new power supply, and there may be short-term current fluctuations during this process. Therefore, collect the actual output current and actual inductor current of the two-way AC / DC conversion module for feedback control.

[0130] Moreover, during the switching process, to improve the dynamic response of the controller, collect the actually output inverted voltage of the two-way AC / DC conversion module as feedforward to ensure seamless tracking of the off-grid inverted voltage to the grid at the moment of switching.

[0131] Based on this, in the embodiments of the present application, please refer to Figure 6 , based on the amplitude and phase of the grid voltage, controlling the amplitude and phase of the inverted voltage output by the two-way AC / DC conversion module, including the following steps S601 - S602:

[0132] S601. Collect the actual inverted voltage, actual output current output by the two-way AC / DC conversion module, and the actual inductor current of the two-way AC / DC conversion module;

[0133] S602. Based on the amplitude and phase of the grid voltage, actual inverted voltage, and the actual output current and actual inductor current, control the amplitude and phase of the inverted voltage output by the two-way AC / DC conversion module, and the magnitude of the actual output current.

[0134] Specifically, based on the amplitude and phase of the grid voltage, the actual inverter voltage, as well as the actual output current and the actual inductor current, control the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module, and the magnitude of the inverter current output, including:

[0135] Generate a first modulation quantity for controlling the amplitude and phase of the inverter voltage based on the amplitude and phase of the grid voltage and the actual inverter voltage output by the bidirectional AC / DC conversion module;

[0136] Based on the actual output current output by the bidirectional AC / DC conversion module and the actual inductor current of the bidirectional AC / DC conversion module, modulate the first modulation quantity again to generate a second modulation quantity that is also used to control the magnitude of the actual output current of the bidirectional AC / DC conversion module;

[0137] Output the second modulation quantity to the bidirectional AC / DC conversion module to control the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module and the magnitude of the actual output current.

[0138] Here, a PWM wave is finally generated based on the first modulation quantity and the second modulation quantity.

[0139] A PWM wave is a signal that regulates the voltage amplitude, phase, and current magnitude by controlling the pulse width. In the AC / DC conversion module, the PWM wave can be used to control parameters such as voltage and current.

[0140] Specifically, the pulse width of the PWM wave determines the conduction time of the AC / DC conversion module, thereby controlling the amplitude and phase of the output voltage. When the pulse width is narrow, the conduction time of the AC / DC conversion module is short, the amplitude of the output voltage is low, and the phase lags; when the pulse width is wide, the conduction time of the AC / DC conversion module is long, the amplitude of the output voltage is high, and the phase leads. Therefore, by adjusting the pulse width of the PWM wave, the amplitude and phase of the output voltage can be controlled.

[0141] At the same time, the PWM wave can also be used to control the magnitude of the current of the AC / DC conversion module. When the pulse width of the PWM wave is narrow, the conduction time of the AC / DC conversion module is short, and the current is small; when the pulse width is wide, the conduction time of the AC / DC conversion module is long, and the current is large. Therefore, by adjusting the pulse width of the PWM wave, the magnitude of the current of the AC / DC conversion module can be controlled.

[0142] In the embodiments of the present application, please refer to Figure 7 , Figure 7The control schematic diagram of the controller according to the embodiments of the present application is shown; the controller includes a voltage loop 702 and a current loop 703. The voltage loop 702 is used to generate a first modulation quantity for controlling the amplitude and phase of the inverter voltage based on the amplitude and phase of the grid voltage and the actual inverter voltage output by the bidirectional AC / DC conversion module. The current loop 703 is used to modulate the first modulation quantity again based on the actual output current output by the bidirectional AC / DC conversion module and the actual inductor current of the bidirectional AC / DC conversion module, and generate a second modulation quantity for further controlling the magnitude of the actual output current of the bidirectional AC / DC conversion module.

[0143] Specifically, generating a first modulation quantity for controlling the amplitude and phase of the inverter voltage based on the amplitude and phase of the grid voltage and the actual inverter voltage output by the bidirectional AC / DC conversion module includes:

[0144] Determining the voltage loop reference of the voltage loop in the controller based on the amplitude and phase of the grid voltage, and using the actual inverter voltage as the voltage loop feedback;

[0145] Adjusting the voltage loop based on the voltage loop reference and the voltage loop feedback to generate a first modulation quantity for controlling the amplitude and phase of the first inverter voltage.

[0146] In the embodiments of the present application, the actual output inverter voltage is added as a feedforward to the adjustment quantity of the voltage loop to improve the dynamic response and ensure seamless tracking of the off-grid inverter voltage at the moment of switching.

[0147] In some embodiments, determining the voltage loop reference of the voltage loop in the controller based on the amplitude and phase of the grid voltage includes:

[0148] Multiplying the amplitude of the grid voltage by the phase to obtain the voltage loop reference of the voltage loop in the controller. Multiplying the amplitude of the grid voltage by the phase determines the voltage value corresponding to this phase.

[0149] Modulating the first modulation quantity again based on the actual output current output by the bidirectional AC / DC conversion module and the actual inductor current of the bidirectional AC / DC conversion module, and generating a second modulation quantity for further controlling the magnitude of the actual output current of the bidirectional AC / DC conversion module includes:

[0150] Using the first modulation quantity output by the voltage loop as the current loop reference of the current loop in the controller, and using the actual output current and the actual inductor current of the bidirectional AC / DC conversion module as the current loop feedback;

[0151] Adjusting the current loop based on the current loop reference and the current loop feedback to generate a second modulation quantity for further controlling the magnitude of the actual output current of the bidirectional AC / DC conversion module.

[0152] Specifically, the loop difference is calculated between the current loop reference and the actual inductor current and the actual output current of the feedback, and the current loop is adjusted to prevent the current received by the load from being too large and damaging the load.

[0153] The following combines Figure 1 and Figure 7 to illustrate the specific control process of the controller of the off-grid energy storage device. When the power grid supplies power to the load and the off-grid energy storage device, and the grid voltage is abnormal and switches from grid power supply to off-grid energy storage device power supply, the specific control process of the controller is as follows: The grid voltage status is monitored in real time; when the power grid is in at least one fault state of overvoltage, undervoltage, underfrequency, overfrequency, or rapid power failure, the grid-side abnormality flag bit is set; the first relay Rly1 is disconnected, and the energy storage device is adjusted from the ACDC control mode to the DCAC inverter control mode; in the inverter control mode, the actual voltage amplitude and phase information (such as the product Uref of the voltage amplitude and phase) at the moment of mains power failure detected in real time are used as the reference of the voltage loop 702 in the inverter mode, and the actual inverter voltage Uout is used as the feedback to adjust the voltage loop 702; the adjustment error is calculated based on the output of the voltage loop 702 (the first modulation quantity) as the reference of the current loop 703 and the inductor current iL and the actual output current iO of the feedback, and the current loop 703 is adjusted; in this way, the actual value feedforward of the inverter voltage is added to the loop adjustment quantity to improve the dynamic response of the system, and the modulation wave PWM signal is output; at this time, the amplitude and phase of the output inverter voltage are the same as those at the moment before the grid voltage abnormality, thus realizing seamless switching of off-grid inversion.

[0154] When the grid voltage returns to normal from the abnormal state and switches from off-grid energy storage device power supply to grid power supply, the specific control process of the controller is as follows: The grid voltage status is monitored in real time. When the power grid returns to normal, the grid-side normal flag is set, the phase information of the grid voltage is locked through the phase-locked loop 701, and the grid voltage is sampled to calculate its amplitude information; the energy storage device uses the actual voltage amplitude and phase information as the reference of the voltage loop 702 in the inverter mode, and the actual inverter voltage Uout is used as the feedback to adjust the voltage loop 702 and track the grid voltage; the output of the voltage loop 702 is used as the reference of the current loop 703, and the actual output current iO and the actual inductor current iL of the energy storage device are used as the feedback of the current loop 703 to adjust the current loop 703, and the modulation wave PWM signal is output to adjust the inverter voltage; when the inverter voltage is the same as the grid voltage in amplitude and phase, the first relay Rly1 is closed, the mains power supplies power to the load, and at the same time the inverter of the energy storage device is blocked and switches to the ACDC working mode to charge the battery, completing the seamless switching after the mains power returns to normal.

[0155] Please refer to Figure 8 and Figure 8The waveform diagram of the load voltage received by the load when the energy storage device and the power grid according to the embodiments of the present application are switched according to the control method is shown. Compared with Figure 2 the switching in the existing manner, the phase, amplitude, and the previous moment of the voltage are continuous and consistent.

[0156] Based on the same inventive concept, an off-grid energy storage device corresponding to the control method of the off-grid energy storage device is also provided in the embodiments of the present application. Since the principle of solving problems by the off-grid energy storage device in the embodiments of the present application is similar to the above control method in the embodiments of the present application, the implementation of the off-grid energy storage device can refer to the implementation of the control method, and the repeated parts will not be described again.

[0157] An embodiment of the present application provides an off-grid energy storage device, including a controller, a bidirectional AC / DC conversion module, a battery pack, and a mode switching switch circuit;

[0158] The mode switching switch circuit is used to supply power to the load through the switching switch state by the power grid through the switching switch circuit, or to supply power to the load by the battery pack through the AC / DC conversion module and the switching switch circuit;

[0159] The controller is used to collect the power grid voltage state data of the power grid;

[0160] When it is determined that the power grid voltage state data meets the pre-configured mode switching condition, the amplitude and phase of the power grid voltage in the power grid voltage state data are obtained; the mode switching condition includes an energy storage-power grid switching condition for switching from battery pack power supply to power grid power supply and a power grid-energy storage switching condition for switching from power grid power supply to battery pack power supply;

[0161] Based on the mode switching condition that the power grid voltage state data meets, the mode switching switch circuit is controlled to perform corresponding switching, and based on the amplitude and phase of the power grid voltage, the amplitude and phase of the inverted voltage output by the bidirectional AC / DC conversion module are controlled, so that the amplitude and phase of the load voltage received by the load before and after the mode switching are in a continuous state.

[0162] In some embodiments, the energy storage-power grid switching condition includes at least one of the following: the power grid returns to normal from a fault state, reaches a preset energy storage-power grid switching time point, and receives an energy storage-power grid switching signal;

[0163] The power grid-energy storage switching condition includes: the power grid is in a fault state, reaches a preset power grid-energy storage switching time point, and receives a power grid-energy storage switching signal;

[0164] Among them, the fault state includes at least one of the following: overvoltage, undervoltage, underfrequency, overfrequency, and the power-off speed is greater than a preset power-off speed threshold.

[0165] In some embodiments, the controller of the off-grid energy storage device is further configured to, before determining that the grid voltage status data meets the pre-configured mode switching condition, when in the grid power supply mode, determine whether the grid is in a fault state based on the grid voltage status data;

[0166] If so, determine that the grid voltage status data meets the grid-storage switching condition;

[0167] Or,

[0168] When in the battery pack power supply mode, determine whether the grid has recovered from the fault state based on the grid voltage status data;

[0169] If so, determine that the grid voltage status data meets the pre-configured storage-grid switching condition.

[0170] In some embodiments, when the controller of the off-grid energy storage device is configured to control the mode switching switch circuit to perform corresponding switching based on the mode switching condition met by the grid voltage status data, and control the amplitude and phase of the inverted voltage output by the bidirectional AC / DC conversion module based on the amplitude and phase of the grid voltage, so that the amplitude and phase of the load voltage input to the load before and after the mode switching are in a continuous state, it is specifically configured to:

[0171] When it is determined that the grid voltage status data meets the grid-storage switching condition, control the mode switching switch circuit to switch from grid power supply to battery pack power supply;

[0172] Generate a first inverted signal based on the amplitude and phase of the grid voltage; the first inverted signal is used to modulate the amplitude and phase of the first inverted voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the first inverted voltage and the first grid voltage are the same;

[0173] Send the first inverted signal to the bidirectional AC / DC conversion module, so that the bidirectional AC / DC conversion module outputs a first inverted voltage based on the first inverted signal.

[0174] In some embodiments, when the controller of the off-grid energy storage device is configured to control the mode switching switch circuit to perform corresponding switching based on the mode switching condition met by the grid voltage status data, and control the amplitude and phase of the inverted voltage output by the bidirectional AC / DC conversion module based on the amplitude and phase of the grid voltage, so that the amplitude and phase of the load voltage input to the load before and after the mode switching are in a continuous state, it is specifically configured to:

[0175] When it is determined that the grid voltage status data meets the storage-grid switching condition, obtain the amplitude and phase of the grid voltage;

[0176] Generate a second inverter signal based on the phase of the amplitude of the second grid voltage of the energized power grid; the second inverter signal is used to modulate the amplitude and phase of the second inverter voltage output by the bidirectional AC / DC conversion module;

[0177] Send the second inverter signal to the bidirectional AC / DC conversion module so that the bidirectional AC / DC conversion module outputs an inverter voltage based on the second inverter signal;

[0178] When the amplitude and phase of the second inverter voltage are the same as those of the grid voltage, control the mode switching switch circuit to switch from battery pack power supply to grid power supply.

[0179] In some embodiments, when the controller of the off-grid energy storage device controls the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module based on the amplitude and phase of the grid voltage, it is specifically used for:

[0180] Collect the actual inverter voltage, actual output current output by the bidirectional AC / DC conversion module, and the actual inductor current of the bidirectional AC / DC conversion module;

[0181] Based on the amplitude and phase of the grid voltage, the actual inverter voltage, the actual output current, and the actual inductor current, control the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module and the magnitude of the actual output current.

[0182] In some embodiments, when the controller of the off-grid energy storage device controls the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module and the magnitude of the output inverter current based on the amplitude and phase of the grid voltage, the actual inverter voltage, the actual output current, and the actual inductor current, it is specifically used for:

[0183] Generate a first modulation quantity for controlling the amplitude and phase of the inverter voltage based on the amplitude and phase of the grid voltage and the actual inverter voltage output by the bidirectional AC / DC conversion module;

[0184] Based on the actual output current output by the bidirectional AC / DC conversion module and the actual inductor current of the bidirectional AC / DC conversion module, modulate the first modulation quantity again to generate a second modulation quantity that is also used to control the magnitude of the actual output current of the bidirectional AC / DC conversion module;

[0185] Output the second modulation quantity to the bidirectional AC / DC conversion module to control the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module and the magnitude of the actual output current.

[0186] In some embodiments, when the controller of the off-grid energy storage device generates a first modulation quantity for controlling the amplitude and phase of the inverted voltage based on the amplitude and phase of the grid voltage and the actual inverted voltage output by the bidirectional AC / DC conversion module, it specifically is used for:

[0187] Determine the voltage loop reference of the voltage loop in the controller based on the amplitude and phase of the grid voltage, and use the actual inverted voltage as the voltage loop feedback;

[0188] Adjust the voltage loop based on the voltage loop reference and voltage loop feedback to generate a first modulation quantity for controlling the amplitude and phase of the first inverted voltage.

[0189] In some embodiments, when the controller of the off-grid energy storage device re-modulates the first modulation quantity based on the actual output current output by the bidirectional AC / DC conversion module and the actual inductor current of the bidirectional AC / DC conversion module to generate a second modulation quantity that is also used to control the magnitude of the actual output current of the bidirectional AC / DC conversion module, it specifically is used for:

[0190] Use the first modulation quantity output by the voltage loop as the current loop reference of the current loop in the controller, and use the actual output current and actual inductor current of the bidirectional AC / DC conversion module as the current loop feedback;

[0191] Adjust the current loop based on the current loop reference and current loop feedback to generate a second modulation quantity that is also used to control the magnitude of the actual output current of the bidirectional AC / DC conversion module.

[0192] In some embodiments, in the off-grid energy storage device, the phase of the grid voltage is acquired based on a phase-locked loop in the controller.

[0193] In some embodiments, when the controller in the off-grid energy storage device determines the voltage loop reference of the voltage loop in the controller based on the amplitude and phase of the grid voltage, it specifically is used for:

[0194] Multiply the amplitude of the grid voltage by the phase to obtain the voltage loop reference of the voltage loop in the controller.

[0195] In some embodiments, the mode switching switch circuit in the off-grid energy storage device includes: a first switch and a second switch; the first switch and the second switch are connected in series;

[0196] The external connection end of the first switch is connected to the grid, and the external connection end of the second switch is connected to the load;

[0197] The series connection end of the first switch and the second switch is connected to the output end of the bidirectional AC / DC conversion module.

[0198] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all embodiments. The components of the embodiments of the present application generally described and illustrated in the accompanying drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0199] It should be noted that the term "including" will be used in the embodiments of the present application to indicate the presence of the stated features thereafter, but does not exclude the addition of other features.

[0200] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems and devices described above can refer to the corresponding processes in the method embodiments, which will not be elaborated herein in the present application. In the several embodiments provided by the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of the modules is only a logical function division, and there can be other division methods in actual implementation. For another example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some communication interfaces, and the indirect couplings or communication connections of the devices or modules can be in electrical, mechanical or other forms.

[0201] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical units, that is, they can be located in one place, or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0202] In addition, the functional units in the various embodiments of the present application can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit.

[0203] When the above-mentioned functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium executable by a processor. Based on such an understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a platform server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical discs that can store program codes.

[0204] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed by this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A control method for an off-grid energy storage device, characterized in that Controller applied to off-grid energy storage device; the off-grid energy storage device further includes a bidirectional AC / DC conversion module, a battery pack, and a mode switching switch circuit; the mode switching switch circuit is used to supply power to a load through the switching switch state, enabling the power grid to supply power to the load through the switching switch circuit, or enabling the battery pack to supply power to the load through the AC / DC conversion module and the switching switch circuit; The control method includes: Collecting grid voltage state data of the power grid; When it is determined that the grid voltage state data meets the pre-configured mode switching conditions, obtaining the amplitude and phase of the grid voltage in the grid voltage state data; the mode switching conditions include an energy storage-grid switching condition for switching from battery pack power supply to grid power supply and a grid-energy storage switching condition for switching from grid power supply to battery pack power supply; Based on the mode switching conditions that the grid voltage state data meets, controlling the mode switching switch circuit to perform corresponding switching, and based on the amplitude and phase of the grid voltage, controlling the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the load voltage received by the load before and after the mode switching are in a continuous state.

2. The control method of the off-grid energy storage device according to claim 1, characterized in that, The energy storage-grid switching conditions include at least one of the following: the power grid resumes normal from a fault state, reaches a preset energy storage-grid switching time point, or receives an energy storage-grid switching signal; The grid-energy storage switching conditions include: the power grid is in a fault state, reaches a preset grid-energy storage switching time point, or receives a grid-energy storage switching signal; Wherein, the fault state includes at least one of the following: overvoltage, undervoltage, underfrequency, overfrequency, and the power-off speed is greater than a preset power-off speed threshold.

3. The control method of the off-grid energy storage device according to claim 2, wherein Before determining that the grid voltage state data meets the pre-configured mode switching conditions, the method further includes: When in the grid power supply mode, judging whether the power grid is in a fault state based on the grid voltage state data; If so, determining that the grid voltage state data meets the grid-energy storage switching conditions; Or, When in the battery pack power supply mode, judging whether the power grid resumes normal from a fault state based on the grid voltage state data; If so, determining that the grid voltage state data meets the pre-configured energy storage-grid switching conditions.

4. The control method of the off-grid energy storage device according to claim 1, characterized in that Based on the mode switching conditions that the grid voltage state data meets, controlling the mode switching switch circuit to perform corresponding switching, and based on the amplitude and phase of the grid voltage, controlling the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the load voltage input to the load before and after the mode switching are in a continuous state, including: When it is determined that the grid voltage state data meets the grid-energy storage switching conditions, controlling the mode switching switch circuit to switch from grid power supply to battery pack power supply; Generating a first inverter signal based on the amplitude and phase of the grid voltage; the first inverter signal is used to modulate the amplitude and phase of the first inverter voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the first inverter voltage and the first grid voltage are the same; Send the first inversion signal to the bidirectional AC / DC conversion module, so that the bidirectional AC / DC conversion module outputs a first inversion voltage based on the first inversion signal.

5. The control method of the off-grid energy storage device according to claim 1, characterized in that, Based on the mode switching conditions met by the grid voltage state data, control the mode switching switch circuit to perform corresponding switching, and based on the amplitude and phase of the grid voltage, control the amplitude and phase of the inversion voltage output by the bidirectional AC / DC conversion module, so that the amplitude and phase of the load voltage input to the load before and after mode switching are in a continuous state, including: When it is determined that the grid voltage state data meets the energy storage-grid switching conditions, obtain the amplitude and phase of the grid voltage; Generate a second inversion signal based on the amplitude and phase of the second grid voltage of the grid in power supply; the second inversion signal is used to modulate the amplitude and phase of the second inversion voltage output by the bidirectional AC / DC conversion module; Send the second inversion signal to the bidirectional AC / DC conversion module, so that the bidirectional AC / DC conversion module outputs an inversion voltage based on the second inversion signal; When the amplitude and phase of the second inversion voltage are consistent with those of the grid voltage, control the mode switching switch circuit to switch from battery pack power supply to grid power supply.

6. The control method of the off-grid energy storage device according to claim 1, wherein Based on the amplitude and phase of the grid voltage, control the amplitude and phase of the inversion voltage output by the bidirectional AC / DC conversion module, including: Collect the actual inversion voltage, actual output current output by the bidirectional AC / DC conversion module, and the actual inductor current of the bidirectional AC / DC conversion module; Based on the amplitude and phase of the grid voltage, actual inversion voltage, actual output current, and actual inductor current, control the amplitude and phase of the inversion voltage output by the bidirectional AC / DC conversion module and the magnitude of the actual output current.

7. The control method of the off-grid energy storage device according to claim 6, characterized in that, Based on the amplitude and phase of the grid voltage, actual inversion voltage, actual output current, and actual inductor current, control the amplitude and phase of the inversion voltage output by the bidirectional AC / DC conversion module and the magnitude of the output inversion current, including: Generate a first modulation quantity for controlling the amplitude and phase of the inversion voltage based on the amplitude and phase of the grid voltage and the actual inversion voltage output by the bidirectional AC / DC conversion module; Based on the actual output current output by the bidirectional AC / DC conversion module and the actual inductor current of the bidirectional AC / DC conversion module, modulate the first modulation quantity again to generate a second modulation quantity that is also used to control the magnitude of the actual output current of the bidirectional AC / DC conversion module; Output the second modulation quantity to the bidirectional AC / DC conversion module to control the amplitude and phase of the inversion voltage output by the bidirectional AC / DC conversion module and the magnitude of the actual output current.

8. The control method of the off-grid energy storage device according to claim 7, wherein Generate a first modulation quantity for controlling the amplitude and phase of the inversion voltage based on the amplitude and phase of the grid voltage and the actual inversion voltage output by the bidirectional AC / DC conversion module, including: Determine the voltage loop reference in the controller based on the amplitude and phase of the grid voltage, and use the actual inversion voltage as the voltage loop feedback; Based on the voltage loop reference and voltage loop feedback, the voltage loop is adjusted to generate a first modulation quantity for controlling the amplitude and phase of the first inverter voltage.

9. The control method of the off-grid energy storage device according to claim 7, wherein Based on the actual output current of the bidirectional AC / DC conversion module and the actual inductor current of the bidirectional AC / DC conversion module, the first modulation quantity is modulated again to generate a second modulation quantity for further controlling the magnitude of the actual output current of the bidirectional AC / DC conversion module, including: Taking the first modulation quantity output by the voltage loop as the current loop reference in the controller, and taking the actual output current and actual inductor current of the bidirectional AC / DC conversion module as the current loop feedback; Based on the current loop reference and current loop feedback, the current loop is adjusted to generate a second modulation quantity for further controlling the magnitude of the actual output current of the bidirectional AC / DC conversion module.

10. The control method of the off-grid energy storage device according to claim 1, wherein The phase of the grid voltage is acquired based on the phase-locked loop in the controller.

11. The control method of the off-grid energy storage device according to claim 8, characterized in that, Determining the voltage loop reference of the voltage loop in the controller based on the amplitude and phase of the grid voltage, including: Multiplying the amplitude of the grid voltage by the phase to obtain the voltage loop reference of the voltage loop in the controller.

12. The control method of the off-grid energy storage device according to claim 1, wherein, The mode switching switch circuit includes: a first switch and a second switch; the first switch and the second switch are connected in series; The external connection end of the first switch is connected to the grid, and the external connection end of the second switch is connected to the load; The series connection end of the first switch and the second switch is connected to the output end of the bidirectional AC / DC conversion module.

13. An off-grid energy storage device, characterized in that, Including a controller, a bidirectional AC / DC conversion module, a battery pack, and a mode switching switch circuit; The mode switching switch circuit is used to supply power to the load through the switching switch circuit by the grid or supply power to the load by the battery pack through the AC / DC conversion module and the switching switch circuit by switching the switch state; The controller is used to collect the grid voltage state data of the grid; When it is determined that the grid voltage state data meets the pre-configured mode switching conditions, the amplitude and phase of the grid voltage in the grid voltage state data are obtained; the mode switching conditions include the energy storage-grid switching condition for switching from battery pack power supply to grid power supply and the grid-energy storage switching condition for switching from grid power supply to battery pack power supply; Based on the mode switching conditions met by the grid voltage state data, the mode switching switch circuit is controlled to perform corresponding switching, and based on the amplitude and phase of the grid voltage, the amplitude and phase of the inverter voltage output by the bidirectional AC / DC conversion module are controlled so that the amplitude and phase of the load voltage received by the load before and after the mode switching are in a continuous state.

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