Energy-saving control method, energy storage power supply and storage medium of energy storage power supply

Abstract

The present application relates to the field of energy storage power supplies, and discloses an energy-saving control method, an energy storage power supply and a storage medium for an energy storage power supply. The energy-saving control method includes: sampling the AC output voltage and the AC output current, and calculating the output apparent power; when the apparent power is greater than or equal to a preset power lower limit threshold, controlling the inverter to operate in a normal mode; when the apparent power is less than the power lower limit threshold, controlling the inverter to operate in a first-level low-power mode, and executing an no-load detection algorithm to determine whether the energy storage power supply is in an no-load state, and if so, controlling the inverter to switch to a second-level low-power mode. The method of the present application can identify light load and no load, and adopt different low-power control strategies in light load and no-load states, significantly reducing the energy loss of the off-grid energy storage power supply under light load or no load.

Description

Technical Field

[0001] The present application relates to the field of energy storage power supplies, and particularly to an energy-saving control method for an energy storage power supply, an energy storage power supply, and a storage medium. Background Art

[0002] In energy storage applications, DC-DC and DC-AC are commonly used to form a two-stage power conversion. When off-grid, the energy storage power supply with such a two-stage structure will cause energy loss due to load changes. How to reduce the energy loss of the energy storage power supply under light load or no load has become an urgent problem to be solved.

[0003] The existing technical solutions mainly detect the output power of the energy storage power supply. When the output power is less than a set threshold value and lasts for a period of time, it is determined that the energy storage power supply is in an idle state and enters a low-power consumption mode, thereby reducing the no-load loss. The defects of this solution are: 1) Limited by the power sampling accuracy, when a small-power load is connected, the energy storage power supply cannot distinguish between light load and no load, and there is a defect of misjudging no load and thus turning off the power output to cause the load to lose power; 2) In the low-power consumption mode, only the control strategy of the DC-DC side is changed, and there are still quite a lot of energy losses. Summary of the Invention

[0004] Embodiments of the present application aim to provide an energy-saving control method for an energy storage power supply, an energy storage power supply, and a storage medium to solve the problem of energy loss of an off-grid energy storage power supply under light load or no load in the prior art.

[0005] To solve the above technical problems, the embodiments of the present application provide the following technical solutions:

[0006] According to a first aspect of the present application, there is provided an energy-saving control method for an energy storage power supply. The energy storage power supply includes an inverter, and the inverter includes a pre-stage DC-DC module and a post-stage DC-AC module. The pre-stage DC-DC module converts a DC input voltage into a DC bus voltage, and the post-stage DC-AC module converts the DC bus voltage into an expected AC output voltage. The method includes:

[0007] Sampling the AC output voltage and the AC output current, and calculating the output apparent power;

[0008] When the apparent power is greater than or equal to a preset power lower limit threshold, controlling the inverter to enter the normal mode for operation;

[0009] When the apparent power is less than the power lower limit threshold, controlling the inverter to enter a first-level low-power consumption mode for operation, and executing an idle detection algorithm to determine whether the energy storage power supply is in an idle state. If so, controlling the inverter to enter a second-level low-power consumption mode for operation;

[0010] Among them, in the first-level low-power mode, the front-stage DC-DC module operates intermittently based on a preset hysteresis response voltage, and the rear-stage DC-AC module modulates the inverter waveform using a sine pulse width modulation mode. In the second-level low-power mode, the front-stage DC-DC module operates intermittently based on the hysteresis response voltage, and the rear-stage DC-AC module modulates the inverter waveform using a trapezoidal pulse width modulation mode.

[0011] Optionally, the hysteresis response voltage includes a lower limit of the hysteresis response voltage and an upper limit of the hysteresis response voltage. The front-stage DC-DC module operating intermittently based on a preset hysteresis response voltage is specifically: when the DC bus voltage is lower than the lower limit of the hysteresis response voltage, the front-stage DC-DC module turns on the pulse drive until the DC bus voltage reaches the upper limit of the hysteresis response voltage, at which point the front-stage DC-DC module stops the pulse drive.

[0012] Optionally, the no-load detection algorithm includes:

[0013] When the inverter operates in the first-level low-power mode, the DC bus voltage is sampled to detect the first duration required for the DC bus voltage to drop from a preset first voltage threshold to a preset second voltage threshold. If the first duration is greater than or equal to a preset discharge duration threshold, it is determined that the energy storage power supply is in a no-load state.

[0014] Optionally, the discharge duration threshold is determined based on the second duration required for the DC bus voltage to drop from the first voltage threshold to the second voltage threshold when the energy storage power supply is in a no-load state and the inverter operates in the first-level low-power mode.

[0015] Optionally, the first voltage threshold is the upper limit of the hysteresis response voltage, and the second voltage threshold is the lower limit of the hysteresis response voltage.

[0016] Optionally, when the inverter operates in the first-level low-power mode, the method further includes:

[0017] Executing the no-load detection algorithm to determine whether the energy storage power supply is in a no-load state;

[0018] If so, control the inverter to switch to the second-level low-power mode for operation;

[0019] If not, sample the AC output voltage and AC output current, calculate the apparent power output, and determine whether the apparent power is greater than or equal to the power lower limit threshold. If so, control the inverter to switch to the normal mode for operation.

[0020] Optionally, when the inverter operates in the second-level low-power mode, the method further includes:

[0021] Continuously detect the AC output voltage;

[0022] When the absolute value of the difference between the detected AC output voltage and the corresponding reference voltage amplitude is greater than a preset first voltage difference threshold, control the inverter to switch to the normal mode of operation;

[0023] When the absolute value of the difference between the detected AC output voltage and the corresponding reference voltage amplitude is continuously detected to be greater than a preset second voltage difference threshold for N times, control the inverter to switch to the first-level low-power mode of operation, where the first voltage difference threshold is greater than the second voltage difference threshold, and N is a preset number of times.

[0024] Optionally, when the post-stage DC-AC module modulates the inverter waveform using the trapezoidal pulse width modulation mode, a trapezoidal wave with a triangularization rate near 0.4 is selected for modulation.

[0025] According to a second aspect of the present application, there is provided an energy storage power supply, including an inverter, the inverter includes a pre-stage DC-DC module, a post-stage DC-AC module, and a controller, the pre-stage DC-DC module converts the DC input voltage into a DC bus voltage, the post-stage DC-AC module converts the DC bus voltage into an expected AC output voltage, the controller is respectively connected to the pre-stage DC-DC module and the post-stage DC-AC module, and the controller includes:

[0026] At least one processor and a memory communicatively connected to the at least one processor, the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the energy-saving control method of the energy storage power supply described above.

[0027] According to a third aspect of the present application, there is provided a computer storage medium, the computer storage medium stores instructions or programs, and when the instructions or programs are executed by at least one processor, the at least one processor is enabled to execute the energy-saving control method of the energy storage power supply described above.

[0028] The beneficial effects of the embodiments of the present application are as follows: Different from the prior art, in the embodiments of the present application, an energy-saving control method for an energy storage power supply is provided. The energy storage power supply includes an inverter, and the inverter includes a front-stage DC-DC module and a rear-stage DC-AC module. When the apparent power is less than the power lower limit threshold, first control the inverter to enter the first-level low-power mode for operation, and then identify whether the energy storage power supply is in an unloaded state. If so, control the inverter to switch to the second-level low-power mode for operation. Among them, in the first-level low-power mode, the front-stage DC-DC module operates intermittently based on a preset hysteresis response voltage, and the rear-stage DC-AC module modulates the inverter waveform using the sine pulse width modulation mode. In the second-level low-power mode, the front-stage DC-DC module operates intermittently based on the hysteresis response voltage, and the rear-stage DC-AC module modulates the inverter waveform using the trapezoidal pulse width modulation mode. The method of the present application can identify light load and no load, and adopt different low-power control strategies in the light load and no load states, significantly reducing the energy loss of the off-grid energy storage power supply under light load or no load. Description of the Drawings

[0029] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the drawings in the drawings do not constitute a proportional limitation.

[0030] Figure 1 is a schematic structural diagram of an energy storage power supply provided by an embodiment of the present application;

[0031] Figure 2 is a schematic structural diagram of the controller provided by an embodiment of the present application;

[0032] Figure 3 is a schematic flowchart of an energy-saving control method for an energy storage power supply provided by an embodiment of the present application;

[0033] Figure 4 is a schematic pulse drive diagram of the front-stage DC-DC module in the normal operation mode and the intermittent operation mode provided by an embodiment of the present application;

[0034] Figure 5 is a schematic diagram of using T-PWM to replace SPWM provided by an embodiment of the present application;

[0035] Figure 6 is a schematic diagram of the relationship curve between the triangularization rate of the trapezoidal wave, the waveform distortion rate, and the DC voltage utilization rate provided by an embodiment of the present application;

[0036] Figure 7 is a schematic flowchart of an unloaded detection algorithm provided by an embodiment of the present application;

[0037] Figure 8 It is a schematic flowchart of determining the discharge duration threshold provided by an embodiment of the present application;

[0038] Figure 9 It is a schematic flowchart of another energy-saving control method for an energy storage power supply provided by an embodiment of the present application. Detailed implementation manners

[0039] 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 with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0040] In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0041] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0042] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of an energy storage power supply provided by an embodiment of the present application. As Figure 1 shown, the energy storage power supply 100 includes a DC power source 10 and an inverter 20. Among them, the inverter 20 includes a front-stage DC-DC module 21, a rear-stage DC-AC module 22, and a controller 23. The front-stage DC-DC module 21 converts the DC input voltage from the DC power source 10 into a DC bus voltage, and the rear-stage DC-AC module 22 converts the DC bus voltage into an expected AC output voltage. The controller 23 is respectively connected to the front-stage DC-DC module 21 and the rear-stage DC-AC module 22, and is used for the drive control of the front-stage DC-DC module 21 and the inverter conversion control of the rear-stage DC-AC module 22.

[0043] In some embodiments, the controller 23 further includes a sampling circuit for sampling the AC output voltage and the AC output current. The controller 23 can adopt a microcontroller unit (MCU) or a digital signal processing (DSP) controller, etc.

[0044] In some embodiments, the energy storage power supply 100 further includes an AC output filter circuit, which is composed of an inductor L and a filter capacitor C2. When a load is connected, the load is connected in parallel with the filter capacitor C2.

[0045] The energy storage power supply 100 can be connected to the power grid in parallel or connected to a local load. The energy-saving control method for the energy storage power supply provided in this application is a solution proposed for the energy loss problem of the off-grid energy storage power supply 100 in a light-load or no-load state.

[0046] Please refer to Figure 2 , Figure 2 An exemplary structure of the controller 23 is shown. As Figure 2 shown, the controller 23 includes at least one processor 231 and a memory 232. Among them, the memory 232 can be built into the controller 23 or external to the controller 23. The memory 232 can also be a remotely set memory, which is connected to the controller 23 through a network.

[0047] The memory 232, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules. The memory 232 can include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data created according to the use of the terminal, etc. In addition, the memory 232 can include high-speed random access memory, and can also include non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state storage devices. In some embodiments, the memory 232 optionally includes a memory remotely set relative to the processor 231, and these remote memories can be connected to the terminal through a network. Examples of the above network include but are not limited to the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0048] The processor 231 executes various functions of the terminal and processes data by running or executing software programs and / or modules stored in the memory 232, and by calling data stored in the memory 232, so as to perform overall monitoring of the terminal. For example, the energy-saving control method for the energy storage power supply provided in any embodiment of this application is implemented.

[0049] The processor 231 can be one or more. Figure 2Taking a processor 231 as an example. The processor 231 and the memory 232 can be connected through a bus or other means. The processor 231 may include a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, etc. The processor 231 can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0050] Please refer to Figure 3 , Figure 3 which is a schematic flow chart of the energy-saving control method for the energy storage power supply provided by the embodiments of the present application. Among them, the energy storage power supply includes an inverter, and the inverter includes a front-stage DC-DC module, a rear-stage DC-AC module, and a controller. Among them, the front-stage DC-DC module converts the DC input voltage into a DC bus voltage, the rear-stage DC-AC module converts the DC bus voltage into an expected AC output voltage, and the controller is respectively connected to the front-stage DC-DC module and the rear-stage DC-AC module for driving control of the front-stage DC-DC module and inverter conversion control of the rear-stage DC-AC module. Among them, in some embodiments, the energy storage power supply here can be implemented through a structure such as Figure 1 - Figure 2 shown, and the specific implementation process has been described in detail in the above embodiments and will not be elaborated here.

[0051] As Figure 3 shown, the energy-saving control method of the energy storage power supply includes:

[0052] Step S301: Sample the AC output voltage and the AC output current, and calculate the output apparent power.

[0053] Sample the AC output voltage and the AC output current of the inverter, and calculate the output apparent power , and the calculation formula is as follows:

[0054]

[0055] Among them, is the total number of sampling points within a sine period, is the th sampling point.

[0056] Step S302: When the apparent power is greater than or equal to the preset power lower limit threshold, control the inverter to enter the normal mode of operation.

[0057] In one embodiment, a lower power threshold of apparent power is preset (for example, 5% of the rated apparent power). When the apparent power is greater than or equal to the power threshold, the inverter enters the normal mode of operation. In the normal mode, the front-stage DC-DC module and the rear-stage DC-AC module of the inverter operate normally according to the existing control strategy. Specifically, the front-stage DC-DC module is in a continuous periodic pulse drive mode, and the rear-stage DC-AC module uses a sine pulse width modulation mode to modulate the inverter waveform.

[0058] Step S303, when the apparent power is less than the power threshold, control the inverter to enter the first-level low-power mode of operation, and execute an no-load detection algorithm to determine whether the energy storage power supply is in an no-load state. If so, control the inverter to switch to the second-level low-power mode of operation.

[0059] When the apparent power is less than the power threshold, the inverter enters the first-level low-power mode, and in the first-level low-power mode, an no-load detection algorithm is executed to determine whether the energy storage power supply is in an no-load state. If so, control the inverter to switch to the second-level low-power mode of operation. In the first-level low-power mode, the front-stage DC-DC module enters an intermittent operation mode and operates intermittently based on a preset hysteresis response voltage, and the rear-stage DC-AC module operates normally and uses a sine pulse width modulation mode to modulate the inverter waveform; in the second-level low-power mode, the front-stage DC-DC module enters an intermittent operation mode, and the modulation method of the inverter waveform of the rear-stage DC-AC module is switched from sine pulse width modulation to trapezoidal pulse width modulation.

[0060] When the energy storage power supply is in a light load / no-load state, the main loss is the switching loss. Therefore, when the inverter operates in the low-power mode, the front-stage DC-DC module switches from the normal continuous operation mode to the intermittent operation mode. As Figure 4 shown, in the intermittent operation mode, the drive pulse of the front-stage DC-DC module is intermittently turned off to reduce the drive loss of the front-stage DC-DC module.

[0061] In the intermittent operation mode, a hysteresis response voltage is set, and the hysteresis response voltage includes a lower limit of the hysteresis response voltage and an upper limit of the hysteresis response voltage. After the front-stage DC-DC module enters the intermittent operation mode, the DC bus voltage is sampled. When it is detected that the DC bus voltage is lower than the lower limit of the hysteresis response voltage, control the front-stage DC-DC module to turn on the pulse drive. Under the action of the pulse drive, the DC bus voltage continuously rises. When it is detected that the DC bus voltage reaches the upper limit of the hysteresis response voltage, control the front-stage DC-DC module to stop the pulse drive.

[0062] In one embodiment, the lower limit of the hysteresis response voltage is the minimum voltage value for the normal operation of the rear-stage DC-AC module. Assume that the rated peak voltage of the energy storage power supply on the inverter side is U ac, the inversion efficiency of the inverter is 95%, that is, the DC bus voltage is at least 1.05ⅹU ac , considering the influence of the hysteresis response delay, the lower limit of the hysteresis response voltage can be selected as 1.1ⅹU ac . The upper limit of the hysteresis response voltage is the maximum value within the range allowed by the hardware.

[0063] When the energy storage power supply is in the no-load state, to improve the utilization rate of the DC bus voltage and further reduce the no-load loss, the subsequent DC-AC module uses the Trapezoidal Pulse Width Modulation (T-PWM) mode to replace the original Sinusoidal Pulse Width Modulation (SPWM) mode to modulate the inversion waveform.

[0064] Please refer to Figure 5 and Figure 6 , Figure 5 is a schematic diagram showing the replacement of SPWM with T-PWM provided by an embodiment of the present application, Figure 6 is a schematic diagram of the relationship curve between the triangularization rate, waveform distortion rate, and DC voltage utilization rate of the trapezoidal wave provided by an embodiment of the present application. Among them, Figure 6 in, the horizontal axis is the triangularization rate , the solid curve is the waveform distortion rate, and the dashed curve is the DC voltage utilization rate. It can be seen from Figure 5 that for modulation signals with the same amplitude, the enclosed area of the trapezoidal wave is significantly larger than that of the sine wave, so that the amplitude of the fundamental component of the trapezoidal wave increases relative to the sine wave, and the utilization rate of the DC bus voltage is improved. It can be seen from Figure 6 that when the triangularization rate is around 0.4 to 0.8, the waveform distortion rate is very low, and the DC voltage utilization rate is higher around 0.4. Preferably, when the subsequent DC-AC module uses the trapezoidal pulse width modulation mode to modulate the inversion waveform, a trapezoidal wave with a triangularization rate around 0.4 is selected for modulation.

[0065] In this application, the no-load detection algorithm is executed when the inverter operates in the first-level low-power mode. In one embodiment, the no-load detection algorithm includes: when the inverter operates in the first-level low-power mode, sampling the DC bus voltage, detecting the first duration required for the DC bus voltage to drop from a preset first voltage threshold to a preset second voltage threshold. If the first duration is greater than or equal to a preset discharge duration threshold, it is determined that the energy storage power supply is in a no-load state. Among them, the first voltage threshold is greater than the second voltage threshold. In one embodiment, the first voltage threshold is the upper limit of the hysteresis response voltage, and the second voltage threshold is the lower limit of the hysteresis response voltage. The discharge duration threshold is the maximum duration required for the DC bus voltage to drop from the first voltage threshold to the second voltage threshold when the inverter operates in the first-level low-power mode, that is, the duration required when the energy storage power supply is in a no-load state. If a load is connected to the energy storage power supply, the DC bus voltage drops faster and takes less time. Therefore, when the first duration is greater than or equal to the discharge duration threshold, it can be determined that the energy storage power supply is in a no-load state.

[0066] Please refer to Figure 7 and Figure 8 , Figure 7 which is a schematic flowchart of a no-load detection algorithm provided by an embodiment of this application, Figure 8 and Figure 7 is a schematic flowchart for determining the discharge duration threshold provided by an embodiment of this application. As

[0067] shown, the flowchart of the no-load detection algorithm includes:

[0068] Step S701, sampling the DC bus voltage.

[0068] Step S702, determining whether the DC bus voltage is less than the lower limit of the hysteresis response voltage. If so, proceed to step S703; if not, proceed to step S701.

[0069] Step S703, turning on the drive pulse of the front-stage DC-DC module to increase the DC bus voltage.

[0070] Step S704, sampling the DC bus voltage.

[0071] Step S705, determining whether the DC bus voltage has risen to the upper limit of the hysteresis response voltage. If so, proceed to step S706; if not, proceed to step S704.

[0072] Step S706, turning off the pulse drive of the front-stage DC-DC module and starting the timer.

[0073] Step S707, sampling the DC bus voltage.

[0074] Step S708, determining whether the DC bus voltage has dropped to the lower limit of the hysteresis response voltage. If so, proceed to step S709; if not, proceed to step S707.

[0075] Step S709, stop the timer from timing and record the timing duration as the first duration.

[0076] Step S710, determine whether the first duration is greater than or equal to a preset discharge duration threshold. If so, proceed to step S711; if not, proceed to step S712.

[0077] Step S711, determine that the energy storage power supply is in an unloaded state.

[0078] Step S712, determine that the energy storage power supply is in a lightly loaded state.

[0079] As Figure 8 shown, the process of determining the discharge duration threshold includes:

[0080] Step S801, after disconnecting the load connected to the energy storage power supply, control the energy storage power supply to turn on.

[0081] Step S802, sample the AC output voltage and AC output current, and calculate the apparent power output.

[0082] Step S803, determine whether the apparent power is less than the power lower limit threshold. If so, proceed to step S804; if not, proceed to step S802.

[0083] Step S804, sample the DC bus voltage.

[0084] Step S805, determine whether the DC bus voltage is less than the lower limit of the hysteresis response voltage. If so, proceed to step S806; if not, proceed to step S804.

[0085] Step S806, turn on the drive pulse of the front-stage DC-DC module to increase the DC bus voltage.

[0086] Step S807, sample the DC bus voltage.

[0087] Step S808, determine whether the DC bus voltage has risen to the upper limit of the hysteresis response voltage. If so, proceed to step S809; if not, proceed to step S807.

[0088] Step S809, turn off the pulse drive of the front-stage DC-DC module and start the timer to time.

[0089] Step S810, sample the DC bus voltage.

[0090] Step S811, determine whether the DC bus voltage has dropped to the lower limit of the hysteresis response voltage. If so, proceed to step S812; if not, proceed to step S810.

[0091] Step S812: Stop the timer and record the timing duration as the second duration.

[0092] Step S813: Determine the discharge duration threshold according to the second duration.

[0093] In one embodiment, the discharge duration threshold is the same as the second duration. After determining the discharge duration threshold, store the discharge duration threshold in the memory of the inverter.

[0094] It should be noted that Figure 7 The no-load detection algorithm of is executed based on the first voltage threshold being the upper limit of the hysteresis response voltage and the second voltage threshold being the lower limit of the hysteresis response voltage. In other embodiments, the first voltage threshold and the second voltage threshold can also be other values that satisfy the following relationship: upper limit of hysteresis response voltage ≥ first voltage threshold > second voltage threshold ≥ lower limit of hysteresis response voltage. When the first voltage threshold is not the upper limit of the hysteresis response voltage and the second voltage threshold is not the lower limit of the hysteresis response voltage, only need to modify steps S706 to S709 in Figure 7 to the following steps:

[0095] Step S706': Turn off the pulse drive of the front-stage DC-DC module.

[0096] Step S707': Sample the DC bus voltage and start the timer when it is detected that the DC bus voltage drops to the first voltage threshold.

[0097] Step S708': Sample the DC bus voltage and stop the timer when it is detected that the DC bus voltage drops to the second voltage threshold.

[0098] Step S709': Record the timing duration as the first duration.

[0099] It can be understood that when the first voltage threshold is not the upper limit of the hysteresis response voltage and the second voltage threshold is not the lower limit of the hysteresis response voltage, the process of determining the discharge duration threshold also needs to be modified accordingly with reference to the above process.

[0100] Based on Figure 3 to Figure 8 the energy-saving control method of the energy storage power supply described above, the working mode of the inverter in the initial state can be determined, and the subsequent working mode of the inverter can be determined based on the current working mode of the inverter and the current detection data.

[0101] Specifically, when the inverter operates in the first - level low - power mode, the energy - saving control method further includes: executing an no - load detection algorithm to determine whether the energy storage power supply is in an no - load state; if so, controlling the inverter to switch to the second - level low - power mode for operation; if not, sampling the AC output voltage and the AC output current, calculating the apparent power output, and determining whether the apparent power is greater than or equal to the power lower - limit threshold. If so, controlling the inverter to switch to the normal mode for operation.

[0102] When the inverter operates in the second - level low - power mode, the energy - saving control method further includes: continuously detecting the AC output voltage. When the absolute value of the difference between the detected AC output voltage and the corresponding reference voltage amplitude is greater than a preset first voltage - difference threshold (i.e., the energy storage power supply is connected to a heavy load), controlling the inverter to switch to the normal mode for operation; when the absolute value of the difference between the detected AC output voltage and the corresponding reference voltage amplitude is greater than a preset second voltage - difference threshold for N consecutive times (i.e., the energy storage power supply is connected to a light load), controlling the inverter to switch to the first - level low - power mode for operation, where the first voltage - difference threshold is greater than the second voltage - difference threshold (for example, the first voltage - difference threshold is 120V and the second voltage - difference threshold is 80V), and N is a preset number. In one embodiment, N = 0.0015×f, where f is the main control interrupt frequency of the inverter. That is, for an AC voltage with a frequency of 50Hz, when the duration of the voltage deviation satisfying the above conditions within one cycle (the duration of one cycle is 20ms) reaches 1.5ms, it is determined that the energy storage power supply is connected to a light load.

[0103] Please refer to Figure 9 , Figure 9 which is the complete process of the energy - saving control method for the energy storage power supply, specifically including:

[0104] Step S901: Sample the AC output voltage and the AC output current, and calculate the apparent power output.

[0105] Step S902: Determine whether the apparent power is less than the power lower - limit threshold. If so, go to step S903; if not, go to step S908.

[0106] Step S903: Control the inverter to enter the first - level low - power mode for operation.

[0107] Step S904: Execute an no - load detection algorithm to determine whether the energy storage power supply is in an no - load state. If so, go to step S905; if not, go to step S901.

[0108] Step S905: Control the inverter to enter the second - level low - power mode for operation.

[0109] Step S906: Determine whether the energy storage power supply is connected to a load. If so, go to step S907; if not, go to step S905.

[0110] Specifically, the AC output voltage is continuously detected by a voltage sensor. When the absolute value of the difference between the detected AC output voltage and the corresponding reference voltage amplitude is greater than the first voltage difference threshold, or when the absolute value of the difference between the detected AC output voltage and the corresponding reference voltage amplitude is greater than the second voltage difference threshold for N consecutive times, it is determined that the energy storage power supply is connected to the load. The meanings of the first voltage difference threshold, the second voltage difference threshold, and N are described in detail above.

[0111] Step S907: Determine whether the energy storage power supply is connected to a heavy load. If so, go to step S908; if not, go to step S903.

[0112] Specifically, when the absolute value of the difference between the detected AC output voltage and the corresponding reference voltage amplitude is greater than the first voltage difference threshold, it is determined that the energy storage power supply is connected to a heavy load.

[0113] Step S908: Control the inverter to operate in the normal mode.

[0114] For the energy storage power supply energy-saving control method provided in this application, the energy storage power supply includes an inverter, and the inverter includes a front-stage DC-DC module and a rear-stage DC-AC module. When the apparent power is less than the power lower limit threshold, first control the inverter to operate in the first-level low-power mode, and then identify whether the energy storage power supply is in an unloaded state. If so, control the inverter to switch to the second-level low-power mode. Among them, in the first-level low-power mode, the front-stage DC-DC module operates intermittently based on a preset hysteresis response voltage, and the rear-stage DC-AC module modulates the inverter waveform using a sine pulse width modulation mode. In the second-level low-power mode, the front-stage DC-DC module operates intermittently based on the hysteresis response voltage, and the rear-stage DC-AC module modulates the inverter waveform using a trapezoidal pulse width modulation mode. The method of this application can identify light loads and unloaded states, and adopt different low-power control strategies in light load and unloaded states, significantly reducing the energy loss of the off-grid energy storage power supply under light load or unloaded conditions.

[0115] According to an embodiment of this application, a computer-readable storage medium is provided. Its type is as described above. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor executes the steps of the energy storage power supply energy-saving control method described above.

[0116] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the essence of the above technical solution, or the part that contributes to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0117] As described above, the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present application. Therefore, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for energy-saving control of an energy storage power supply, characterized in that: The energy storage power supply includes an inverter, the inverter includes a front-stage DC-DC module and a rear-stage DC-AC module, the front-stage DC-DC module converts a DC input voltage into a DC bus voltage, and the rear-stage DC-AC module converts the DC bus voltage into an expected AC output voltage. The method includes: Sampling the AC output voltage and AC output current, and calculating the output apparent power; When the apparent power is greater than or equal to a preset power lower limit threshold, controlling the inverter to enter a normal mode of operation; When the apparent power is less than the power lower limit threshold, the inverter is controlled to enter the first-level low power consumption mode, and the no-load detection algorithm is executed to determine whether the energy storage power supply is in a no-load state. If so, the inverter is controlled to switch to the second-level low power consumption mode; Wherein, in the first-level low power consumption mode, the front-stage DC-DC module works intermittently based on the preset hysteresis response voltage, and the rear-stage DC-AC module modulates the inverter waveform using a sinusoidal pulse width modulation mode; in the second-level low power consumption mode, the front-stage DC-DC module works intermittently based on the hysteresis response voltage, and the rear-stage DC-AC module modulates the inverter waveform using a trapezoidal pulse width modulation mode; The no-load detection algorithm includes: When the inverter operates in the first-level low power consumption mode, the DC bus voltage is sampled to detect the first time duration required for the DC bus voltage to drop from a preset first voltage threshold to a preset second voltage threshold. If the first time duration is greater than or equal to a preset discharge time duration threshold, it is determined that the energy storage power supply is in a no-load state.

2. The method according to claim 1, characterized in that The hysteresis response voltage includes a hysteresis response voltage lower limit and a hysteresis response voltage upper limit. The front-stage DC-DC module works intermittently based on the preset hysteresis response voltage: when the DC bus voltage is lower than the hysteresis response voltage lower limit, the front-stage DC-DC module starts pulse driving until the DC bus voltage reaches the hysteresis response voltage upper limit, and the front-stage DC-DC module stops pulse driving.

3. The method according to claim 1, characterized in that The discharge time threshold is determined based on a second time required for the DC bus voltage to drop from the first voltage threshold to the second voltage threshold when the energy storage power supply is in a no-load state and the inverter operates in a primary low power consumption mode.

4. The method according to claim 2, characterized in that: The first voltage threshold is the upper limit of the hysteresis response voltage, and the second voltage threshold is the lower limit of the hysteresis response voltage.

5. The method according to any one of claims 1 to 4, characterized in that: When the inverter operates in the first-level low power consumption mode, the method further includes: Executing the no-load detection algorithm to determine whether the energy storage power supply is in a no-load state; If yes, control the inverter to switch to the secondary low power consumption mode; If not, the AC output voltage and the AC output current are sampled, the output apparent power is calculated, and it is determined whether the apparent power is greater than or equal to the power lower limit threshold. If so, the inverter is controlled to switch to normal mode.

6. The method according to any one of claims 1 to 4, characterized in that: When the inverter operates in the secondary low power consumption mode, the method further includes: Continuously detect the AC output voltage; When it is detected that the absolute value of the difference between the AC output voltage and the corresponding reference voltage amplitude is greater than a preset first voltage difference threshold, controlling the inverter to switch to a normal mode of operation; When the absolute value of the difference between the AC output voltage and the corresponding reference voltage amplitude is detected to be greater than a preset second voltage difference threshold for N consecutive times, the inverter is controlled to switch to a first-level low power consumption mode, the first voltage difference threshold is greater than the second voltage difference threshold, and N is a preset number of times.

7. The method according to any one of claims 1 to 4, characterized in that: When the latter DC-AC module adopts the trapezoidal pulse width modulation mode to modulate the inverter waveform, a trapezoidal wave with a triangular ratio of about 0.4 is selected for modulation.

8. An energy storage power supply, characterized in that: The inverter includes a front-stage DC-DC module, a rear-stage DC-AC module and a controller. The front-stage DC-DC module converts a DC input voltage into a DC bus voltage. The rear-stage DC-AC module converts the DC bus voltage into an expected AC output voltage. The controller is connected to the front-stage DC-DC module and the rear-stage DC-AC module respectively. The controller includes: At least one processor and a memory communicatively connected to the at least one processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor so that the at least one processor can execute the energy-saving control method for the energy storage power supply as described in any one of claims 1 to 7.

9. A computer storage medium, characterized in that: The computer storage medium stores instructions or programs, and when the instructions or programs are executed by at least one processor, the at least one processor executes the energy-saving control method for the energy storage power supply as described in any one of claims 1 to 7.

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