Integral Grid-Connected Control Method, System and Storage Medium

Abstract

The present invention discloses an integral grid-connected control method, system and storage medium. The method includes: sampling a reference voltage value of a bus voltage at a previous moment, and filtering the sampled reference voltage value; storing the filtered reference voltage value after a preset time delay to obtain a delay value; acquiring a real-time value of the bus voltage at the current moment, and calculating the delay value and the real-time value to obtain an average value of the bus voltage; selecting the average value through a data selector to output a feedback value of the bus voltage to the power grid. By storing the real-time value after a preset time delay to obtain a delay value, then calculating the real-time value and the delay value to obtain the average value of the bus voltage, selecting the average value through a data selector to obtain a feedback value, and then outputting the feedback value to the power grid, a stable and pure feedback value of the bus voltage can be obtained, enabling the power grid to be stably controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of smart power grids, and in particular, to an integral grid connection control method, system, and storage medium. Background Art

[0002] As one of the essential energy sources in our lives, the quality of electric energy is directly related to the living quality of users and the lifespan of electrical equipment. Among them, converting and storing energy through solar energy for users to use is not only clean and convenient but also can obtain more benefits. And to store solar energy, a energy storage system needs to be used for control.

[0003] Currently, for the quality and stability of the energy in the energy storage system, the software of the energy storage inverter in the energy storage system plays a decisive role. Generally, the software of the energy storage inverter includes: solar maximum power point tracking (MPPT) control, battery DC-DC power control, and grid AC-DC control, etc. Among them, the battery DC-DC power control is relatively fixed, using a voltage-current double closed-loop control algorithm; the grid AC-DC control is relatively complex, mainly including grid connection control strategies and off-grid control strategies. However, among the many controls of the energy storage system, the secondary ripple disturbance of the bus voltage has a greater impact on the control strategies in the energy storage system. If the design of the bus capacitor is relatively unreasonable in terms of hardware, the ripple is greater, resulting in a significant reduction in grid connection performance, polluting the grid, and at the same time interfering with other electrical equipment and reducing their service life. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. For this purpose, the present invention proposes an integral grid connection control method that can output a stable feedback value to the grid, enabling the grid to operate normally and be stably controlled.

[0005] The present invention also proposes an integral grid connection control system.

[0006] The present invention also proposes a computer-readable storage medium.

[0007] In a first aspect, an embodiment of the present invention provides an integral grid connection control method, including:

[0008] Sampling the reference voltage value of the bus voltage at the previous moment, and filtering the sampled reference voltage value;

[0009] Storing the filtered reference voltage value after a preset time delay to obtain a delay value;

[0010] Obtaining the real-time value of the bus voltage at the current moment, and calculating the delay value and the real-time value to obtain the average value of the bus voltage;

[0011] Select the average value through a data selector to output the feedback value of the bus voltage to the power grid.

[0012] The integral grid-connection control method according to the embodiment of the present invention has at least the following beneficial effects: by sampling the reference voltage value of the bus voltage, filtering the sampled reference voltage value to obtain a pure reference voltage value, then storing it after a preset delay time to obtain a delay value, and then calculating the real-time value and the delay value to obtain the average value of the bus voltage. The average value is selected through a data selector to obtain a feedback value, and the feedback value is output to the power grid to obtain a stable and pure feedback value of the bus voltage, so as to stabilize the grid control.

[0013] According to another embodiment of the integral grid-connection control method of the present invention, the step of obtaining the real-time value of the current bus voltage and calculating the delay value and the real-time value to obtain the average value of the bus voltage includes:

[0014] Obtain the real-time value of the current bus voltage;

[0015] Subtract the delay value from the real-time value to obtain a difference;

[0016] Integrate the difference as an integral accumulation amount to obtain the average value of the bus voltage.

[0017] According to another embodiment of the integral grid-connection control method of the present invention, the sampling frequency of the real-time value is twice the control frequency of the grid-connected inverter control.

[0018] According to another embodiment of the integral grid-connection control method of the present invention, it further includes:

[0019] Perform low-frequency filtering on the average value.

[0020] According to another embodiment of the integral grid-connection control method of the present invention, it further includes:

[0021] Obtain the feedback value as a compensation and error correction amount;

[0022] Dynamically adjust the average value according to the compensation and error correction amount to obtain a final average value, and output the final average value to the data selector.

[0023] According to another embodiment of the integral grid-connection control method of the present invention, the preset time is half a cycle.

[0024] According to another embodiment of the integral grid-connection control method of the present invention, it further includes:

[0025] The set value of the bus voltage and the feedback value are controlled by a voltage loop to form a control current;

[0026] Sample the inductor current and perform current prediction to obtain a predicted current;

[0027] Superimpose the predicted current and the control current and output them to the current loop;

[0028] The current loop adjusts the predicted current and the control current to output a grid-connected current to the single-phase inverter;

[0029] The single-phase inverter converts the grid-connected current into direct current and outputs it to the power grid.

[0030] In a second aspect, an embodiment of the present invention provides an integral grid-connected control system, including:

[0031] A sampling module for collecting the reference voltage value of the bus voltage, the reference voltage value at the previous moment and the real-time value at the current moment;

[0032] A first filtering module for filtering the reference voltage value;

[0033] A delay storage module for storing the reference voltage value after a preset time delay to obtain a delay value;

[0034] A data processing module for calculating the real-time value and the delay value to obtain the average value of the bus voltage;

[0035] A data selector for selecting the average value to output a feedback value to the power grid.

[0036] The integral grid-connected control system according to the embodiment of the present invention has at least the following beneficial effects: By sampling the reference voltage value and the real-time value of the bus voltage, the sampled reference voltage value is filtered to obtain a pure reference voltage value, then the reference voltage value is stored after a preset time delay to obtain a delay value, and then the real-time value and the delay value are calculated to obtain the average value of the bus voltage. The obtained average value is selected by the data selector to obtain a feedback value and output it to the power grid, so as to obtain a stable and pure feedback value of the bus voltage, which does not affect the control of the power grid and enables the power grid to be stably controlled.

[0037] According to another embodiment of the present invention, the integral grid-connected control system further includes:

[0038] A second filtering module for performing low-frequency filtering on the average value and outputting the average value to the data selector.

[0039] According to another embodiment of the present invention, the integral grid-connected control system further includes:

[0040] A driving module for outputting a driving signal;

[0041] A conversion module is configured to convert the feedback value of the AC signal into the feedback value of the DC signal according to the driving signal.

[0042] According to some other embodiments of the present invention, for the integral grid-connected control system, the conversion module is a single-phase grid-connected inverter with an H6 bridge topology.

[0043] In a third aspect, an embodiment of the present invention provides a computer-readable storage medium, which stores computer-executable instructions for causing a computer to execute an integral grid-connected control method as described in the first aspect.

[0044] Other features and advantages of the present application will be described in the subsequent specification, and will, in part, be obvious from the specification, or be understood by implementing the present application. The objectives and other advantages of the present application can be realized and obtained through the structures specifically pointed out in the specification, the claims, and the drawings. Description of the Drawings

[0045] Figure 1 It is a schematic flowchart of a specific embodiment of the integral grid-connected control method in an embodiment of the present invention;

[0046] Figure 2 It is a schematic flowchart of another specific embodiment of the integral grid-connected control method in an embodiment of the present invention;

[0047] Figure 3 It is a schematic flowchart of another specific embodiment of the integral grid-connected control method in an embodiment of the present invention;

[0048] Figure 4 It is a schematic flowchart of another specific embodiment of the integral grid-connected control method in an embodiment of the present invention;

[0049] Figure 5 It is a schematic flowchart of another specific embodiment of the integral grid-connected control method in an embodiment of the present invention;

[0050] Figure 6 It is a schematic flowchart of another specific embodiment of the integral grid-connected control method in an embodiment of the present invention;

[0051] Figure 7 It is a schematic block diagram of a specific embodiment of the integral grid-connected control system in an embodiment of the present invention;

[0052] Figure 8 It is a schematic circuit diagram of a specific embodiment of the integral grid-connected control system in an embodiment of the present invention.

[0053] Reference numerals: 100, sampling module; 200, first filtering module; 300, delay storage module; 400, data processing module; 500, data selector; 600, second filtering module; 700, driving module; 800, conversion module. Detailed implementation manners

[0054] The following will clearly and completely describe the concept and the resulting technical effects of the present invention in conjunction with embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts all fall within the scope of protection of the present invention.

[0055] In the description of the embodiments of the present invention, if "several" is involved, it means more than one; if "multiple" is involved, it means more than two; if "greater than", "less than", "exceeding" are involved, they should all be understood as not including the number itself; if "above", "below", "within" are involved, they should all be understood as including the number itself. If "first" and "second" are involved, they should be understood as used to distinguish technical features, rather than indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0056] Traditional energy storage systems include: energy storage inverter software, EMS energy management software, user software, etc. EMS energy management software and user software have a greater impact on the user experience, while the energy storage inverter software plays a decisive role in the energy quality, stability, etc. of the energy storage system. Among them, the energy storage inverter software includes: solar maximum power tracking control system, battery DC-DC power control system, grid AC-DC control system, etc. Among them, the solar maximum power tracking control system commonly uses some MPPT algorithms combined with intelligent tracking, such as delt_P / delt_V maximum power point tracking, UI maximum power point tracking, and multi-peak tracking. The battery DC-DC power control is relatively fixed, generally using a voltage-current double closed-loop control algorithm. The grid AC-DC control system mainly includes: grid-connected control method and off-grid control method. Among them, the control method of the AC-DC control system is generally a voltage outer loop and a current inner loop. By optimizing the controller, the stability and accuracy of the AC-DC control system are improved, and thus the performance of the grid-connected control method and the off-grid control method is improved. However, the secondary ripple disturbance of the bus voltage affects the control in the AC-DC control system. If the bus capacitor design is relatively unreasonable, the ripple is greater, resulting in a significant reduction in the grid-connected performance, polluting the grid, interfering with other electrical equipment at the same time, and reducing its service life.

[0057] To this end, the present application provides an integral grid-connected control method, which integrates the ripple period of the bus voltage and takes the average value to obtain stable feedback data for AC-DC control.

[0058] In a first aspect, referring to Figure 1 , an embodiment of the present invention discloses an integral grid-connected control method, including:

[0059] S100. Sample the reference voltage value of the bus voltage at the previous moment, and filter the sampled reference voltage value.

[0060] Among them, the reference voltage value of the bus voltage at the previous moment is obtained through AD sampling, and then the reference voltage value is filtered, and the filtering is RC filtering. The high-frequency noise in the reference voltage value is removed through RC filtering to obtain a pure and stable reference voltage value.

[0061] S200. Store the filtered reference voltage value after a preset time delay to obtain a delay value.

[0062] After filtering the reference voltage value, it needs to be delayed for a preset time before storage, so as to obtain the delay value of the bus voltage after delay.

[0063] S300. Obtain the real-time value of the bus voltage at the current moment, and calculate the delay value and the real-time value to obtain the average value of the bus voltage.

[0064] Among them, the reference voltage value and the real-time value differ by a preset time period, that is, if the reference voltage value is obtained at the first moment and the real-time value is obtained at the second moment. At the third moment, the real-time value at the second moment becomes the reference voltage value, and then the real-time value is re-obtained at the third moment to replace the real-time value at the second moment. By calculating the delay value and the real-time value to obtain the average value, the average value of the pure and stable bus voltage is initially obtained, and the noise in the bus voltage is reduced.

[0065] S400. Select the average value through a data selector to output the feedback value of the bus voltage to the power grid.

[0066] Among them, the data selector mainly selects slow and stable signals and fast and abrupt signals.

[0067] After sampling the reference voltage value of the bus voltage and filtering it to eliminate the noise in the reference voltage value of the bus voltage, a relatively pure reference voltage value is obtained. Then, the reference voltage value is delayed by a preset time and stored to obtain a delay value, and the delay value and the real-time value are calculated to obtain an average value. The average value selects the slow and stable signal and the fast and mutant signal in the bus voltage through a data selector to increase the cut-off frequency of the average value sampling, so as to obtain a relatively pure and stable feedback value of the bus voltage. By outputting the feedback value to the power grid, it participates in the double-loop control of the power grid, thereby improving the performance of the AC-DC control system, obtaining a stable and pure feedback value and inputting it into the power grid, so that the power grid can receive stable and pure electric energy.

[0068] In some embodiments, since the bus in the power grid will be subject to power shocks from functional modules such as photovoltaics and batteries, the grid-connected inverter control system needs to have a relatively fast response speed. Therefore, the sampling frequency of the reference voltage value is at least twice the control frequency of the grid-connected inverter control, where the control frequency of the grid-connected inverter control is the control frequency of the integration grid-connected control method. In this embodiment, the sampling frequency is twice the control frequency of the grid-connected inverter control, and in other embodiments, it can be three times, four times, etc. By setting the sampling frequency to be twice the control frequency of the grid-connected inverter control, the control frequency and the sampling frequency will not be aliased, increasing the response speed of the grid-connected inverter control. By AD sampling the reference voltage value of the bus voltage at the previous moment, the reference voltage value is filtered by an RC filter, which is a first-order RC filter, to filter out high-frequency noise above the filter cut-off frequency, and the filter algorithm formula for filtering the reference voltage value by the RC filter is:

[0069] Yn = α * Xn+(1 - α) * Yn-1 (1)

[0070] where α = 2 * Π * △t * Fc, α = filter coefficient; X(n) = current sampling value; Y(n - 1) = previous filter output value; Y(n) = current filter output value. Therefore, X(n) is the value before filtering the reference voltage value, and Y(n) is the value after filtering the reference voltage value.

[0071] In some embodiments, since the ripple of the bus voltage is an inherent frequency disturbance, and the inherent frequency is twice the frequency of the grid voltage, the preset time is half a cycle, so as to delay the reference voltage value by half a cycle and then store it to obtain a delay value, so that the delay value and the real-time value can be calculated to obtain a stable and pure average value.

[0072] Refer to Figure 2 , in some embodiments, step S300 specifically includes:

[0073] S310. Obtain the real-time value of the current bus voltage;

[0074] S320. Subtract the delay value from the real-time value to obtain a difference value.

[0075] S330. Use the difference value as the integral cumulative amount for integral operation to obtain the average value of the bus voltage.

[0076] Among them, the delay value is obtained by delaying the real-time value by half a cycle, then the delay value and the real-time value are subtracted to obtain a difference value, and the difference value is used as the integral cumulative amount for integral operation to obtain the average value of the bus voltage. The calculation formula for the average value of the bus voltage is

[0077]

[0078] In the formula, Bus_Aug is the average value, Bus_Vlot is the real-time value, and Bus_Dely is the delay value.

[0079] By subtracting and then integrating according to the real-time value and the delay value to obtain the average value of the bus voltage, a more accurate bus voltage value can be obtained.

[0080] Refer to Figure 3 , in some embodiments, the integral grid connection control method further includes:

[0081] S500. Perform low-frequency filtering on the average value.

[0082] Since there are high-frequency signals such as steps in the process of subtracting the real-time value and the delay value, this will cause greater disturbance to the inverter grid connection control system. Therefore, low-frequency filtering is performed on the calculated average value of the bus voltage to filter out high-frequency interference signals, making the feedback value input to the power grid more stable. Specifically, the low-frequency filtering uses the same low-pass filtering as the RC filtering.

[0083] Refer to Figure 4 , in some embodiments, the integral grid connection control method further includes:

[0084] S600. Obtain a feedback value as the compensation and error correction amount.

[0085] S700. Dynamically adjust the average value according to the compensation and error correction amount to obtain the final average value, and output the final average value to the data selector.

[0086] Among them, since integral operation is introduced in the integral grid-connection control method, the accumulation of storage errors in the integral operation, that is, the so-called "integral floating phenomenon", and this error is irreversible, which will cause a deviation between the finally obtained feedback value and the true value. The long-term deviation accumulates to a certain amount exceeding the hardware limit and will damage the system hardware. Therefore, the feedback value of the bus voltage is obtained periodically as a compensation and error correction amount for this integral for dynamic adjustment to obtain the final average value, thereby improving the redundancy and stability of the system. Among them, the calculation formula for dynamically adjusting the final average value according to the feedback value as the compensation and error correction amount is:

[0087] Bus_Avg=CompRadioA·Bus_Avg+CmpRadio·Bus_Avg_Cal (3)

[0088] In the formula, CmpRadioA is the first compensation factor, CmpRadioB is the second compensation factor, and in this embodiment, the first compensation factor is 0.8 and the second compensation factor is 0.2.

[0089] By using the feedback value as the error correction amount, specifically, the feedback value is compared with the filtered real-time value. If the difference between the filtered real-time value and the feedback value is obvious, it is excluded, and the second real-time value close to the feedback value is retained, so as to exclude the real-time value with too large error, thereby improving the accuracy of the feedback value calculation.

[0090] In some embodiments, the data selector is an instantaneous switch, and the slow stable signal and the fast mutation signal in the average value of the bus voltage are optimally selected through the instantaneous switch to increase the cut-off frequency of the sampling, thereby increasing the response speed of the grid-connected inverter control.

[0091] Finally, the obtained relatively pure and stable feedback value of the bus voltage participates in the double-loop control in the power grid, so that the power grid receives a stable bus voltage.

[0092] Referring to Figure 5 and Figure 6 , in some embodiments, the integral grid-connection control method further includes:

[0093] S800. The set value and the feedback value of the bus voltage are controlled by a voltage loop to form a control current;

[0094] S900. Sample the inductor current and perform current prediction to obtain a predicted current;

[0095] S1000. Superimpose the predicted current and the control current and output them to the current loop control;

[0096] S1100. The current loop adjusts the predicted current and the control current and outputs a grid-connected current to the single-phase inverter;

[0097] The single-phase inverter S1200 converts the grid-connected current into direct current for output to the grid.

[0098] Among them, the control current is calculated based on the set value and the feedback value of the bus voltage, and then the predicted current is obtained through inductor sampling. Then, the predicted current and the control current are superimposed to output the value current loop. Among them, according to the dual-loop control algorithm, the current loop adjusts the current, power, and PF of the predicted current and the control current to meet the set requirements to form the grid-connected current, and outputs the grid-connected current to the single-phase inverter. The single-phase inverter converts the grid-connected current into direct current for output to the grid. Through rapid sampling of the inductor current and then predicting the inductor current to obtain the predicted current, the predicted current and the control current are superimposed to form a larger current value, making grid connection control easier. Since there will be a time delay when sampling the inductor current according to the sampling frequency, and the predicted current is obtained by predicting the inductor current, there is no need to wait for the inductor current to be sampled before outputting it. Then, according to the superposition of the predicted current and the control current, the control speed of grid-connected inverter control can be accelerated to obtain a high-quality grid-connected current waveform. Among them, the calculation formula for predicting the inductor current to obtain the predicted current is:

[0099] I_fb = I_Curr + Radio·(I_Curr - I_Last) (4)

[0100] In the formula, I_fb is the predicted current, I_Curr is the inductor current, Radio is the prediction parameter, and I_Last is the inductor current at the previous moment.

[0101] The predicted current is calculated according to formula (4), that is, the next inductor current is predicted by the currently collected inductor current to obtain the predicted current. The predicted current can improve the speed of current control to obtain a high-quality grid-connected current waveform.

[0102] Next, refer to Figures 1 to 6 A specific embodiment is used to describe in detail an integral grid connection control method according to an embodiment of the present invention. It should be understood that the following description is only an exemplary illustration and not a specific limitation of the invention.

[0103] The reference voltage value of the bus voltage at the previous moment is obtained through AD sampling, and then the reference voltage value is filtered by RC to filter out high-frequency noise above the cut-off frequency, so as to obtain a pure reference voltage value. After obtaining the reference voltage value, it is stored after a half-cycle delay to obtain a delay value, and then the delay value is subtracted from the real-time value obtained at the current moment to obtain a difference value. This difference value is used as an integral cumulative quantity for integral operation to obtain the average value of the bus voltage. Then, low-pass filtering is performed on the average value of the bus voltage to filter out high-frequency interference signals. The average value after low-pass filtering is dynamically adjusted according to the feedback value as a compensation and error correction quantity to obtain the final average value. The final average value is optimized and selected for slow stable signals and fast mutation signals through an instantaneous switch to obtain a pure and stable feedback value of the bus voltage. The feedback value and the set value of the bus voltage are controlled through a voltage loop to obtain a control current. Then, the inductor current is sampled, and the sampled inductor current is predicted to obtain a predicted current. The predicted current and the control current are superimposed and output to the current loop control, and then the grid-connected current value is output through the current loop. The single-phase inverter converts the direct current and outputs the direct current to the power grid. By predicting the current, the speed of the current loop control is increased, and a high-quality grid-connected current waveform is obtained without affecting the stability of the power grid.

[0104] In a second aspect, referring to Figure 7 , an integral type grid-connected control system according to an embodiment of the present invention further includes: a sampling module 100, a first filtering module 200, a delay storage module 300, a data processing module 400, and a data selector 500; the sampling module 100 is configured to collect the reference voltage value of the bus voltage at the previous moment and the real-time value at the current moment; the first filtering module 200 is configured to perform filtering processing on the reference voltage value; the delay storage module 300 is configured to store the reference voltage value after a preset time delay to obtain a delay value; the data processing module 400 is configured to calculate the real-time value and the delay value to obtain the average value of the bus voltage; the data selector 500 is configured to select the average value to output a feedback value to the power grid.

[0105] After the sampling module 100 collects the reference voltage value of the bus voltage, the first filtering module 200 performs filtering processing on the reference voltage value to obtain a pure reference voltage value, and then the delay storage module 300 stores the reference voltage value after a preset time delay to obtain a delay value. The data processing module 400 calculates the real-time value and the delay value to obtain the average value of the bus voltage. Finally, the average value is selected by the data selector 500 to obtain the feedback value of the bus voltage, and the feedback value is output to the power grid, so that the power grid can be stably controlled.

[0106] An integral grid-connected control system further includes: a second filtering module 600; the second filtering module 600 is used to perform low-frequency filtering on the average value and output the average value to the data selector 500.

[0107] The second filtering module 600 performs low-frequency filtering on the average value to remove the noise in the average value and obtain a pure average value.

[0108] In some embodiments, an integral grid-connected control system further includes: a driving module 700 and a conversion module 800. The driving module 700 is used to output a driving signal. The conversion module 800 is used to receive the driving signal and control the conversion of the feedback value of the AC signal into the feedback value of the DC signal according to the driving signal.

[0109] Since the reference voltage value sampled by the sampling module 100 is an AC signal, only an AC signal can delay the reference voltage value to obtain a delay value, calculate the delay value and the real-time value to obtain an average value, and then obtain a feedback value through the data selector 500. The process of data calculation needs to be completed by an AC signal. However, the current signal received by the power grid is a DC signal, so the conversion module 800 needs to convert the feedback value of the AC signal into the feedback value of the DC signal. At the same time, the conversion module 800 is driven according to the driving signal output by the driving module 700 to realize the function of converting the AC signal into the DC signal.

[0110] Among them, the sampling module 100, the delay storage module 300, the data processing module 400, the data selector 500, and the driving module 700 are integrated in a control chip, and the integral grid-connected control algorithm and the digital double closed-loop control algorithm are stored in the control chip. The control chip performs data delay, calculation, and averaging according to the integral grid-connected control algorithm to obtain a stable feedback value. The control chip outputs a corresponding driving signal according to the digital double closed-loop control algorithm to control the conversion function of the conversion module 800. The model of the control chip is DSP-TMS28069, and the control chip is connected to the conversion module 800. The conversion module 800 is connected to the power grid. The conversion module 800 converts the feedback value of the AC signal into the feedback value of the DC signal according to the driving signal output by the control chip and inputs it to the power grid, so that the power grid can receive electric energy normally.

[0111] Refer to Figure 7 and Figure 8 , in some embodiments, the conversion module 800 is a single-phase grid-connected inverter with an H6 bridge topology, and the single-phase grid-connected inverter with an H6 bridge topology is composed of 6 MOS transistors, 2 diodes, several filter capacitors, and several inductors. The circuit connection structure screenshots of the 6 MOS transistors, 2 diodes, several filter capacitors, and several inductors refer to Figure 6Among them, the six MOS transistors are respectively defined as the first MOS transistor S1, the second MOS transistor S2, the third MOS transistor S3, the fourth MOS transistor S4, the fifth MOS transistor S5, and the sixth MOS transistor S6, and the two diodes are respectively defined as the first diode D1 and the second diode D2. The first MOS transistor S1, the fifth MOS transistor S5, and the sixth MOS transistor S6 form the first bridge arm, and the second MOS transistor S2, the third MOS transistor S3, and the fourth MOS transistor S4 form the second bridge arm. When the current is a positive current, the current flow direction of the first bridge arm is that the current flows in from Bus+, and then flows in the order of the first MOS transistor S1, the fifth inductor L5, the fifth MOS transistor S5, or the sixth MOS transistor S6, and the freewheeling loop is: flowing from the fifth inductor L5 to the fifth MOS transistor S5 and the second diode D2. When the current is a negative current: it flows in from BUS_-, and flows in the order of the third MOS transistor S3, the first diode D1, the sixth inductor L6, the first MOS transistor S1, and Bus_+, and the freewheeling loop from the sixth inductor L6 to the second MOS transistor S2 and the first diode D1. The working principle of the second bridge arm is the same as that of the first bridge arm, which will not be elaborated here. The driving signals output by the control chip are used to control the opening and closing of the first MOS transistor S1, the second MOS transistor S2, the third MOS transistor S3, the fourth MOS transistor S4, the fifth MOS transistor S5, and the sixth MOS transistor S6, so as to realize the function of converting the AC signal into a DC signal.

[0112] Among them, the execution process of an integral grid-connected control system specifically refers to the integral grid-connected control method in the first aspect, which will not be elaborated here.

[0113] In the third aspect, the embodiments of the present invention also disclose a computer-readable storage medium, which stores computer-executable instructions for causing a computer to execute an integral grid-connected control method as in the first aspect.

[0114] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0115] Those of ordinary skill in the art will understand that all or some of the steps and systems disclosed in the above methods can be implemented as software, firmware, hardware, and their appropriate combinations. Some physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or can be implemented as hardware, or can be implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include a computer storage medium (or non-transitory medium) and a communication medium (or transitory medium). As is well known to those of ordinary skill in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassettes, tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those of ordinary skill in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transmission mechanism, and can include any information delivery medium.

[0116] The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the scope of knowledge possessed by those of ordinary skill in the relevant technical field. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. An integral grid-connected control method, characterized in that, Including: Sampling the reference voltage value of the bus voltage at the previous moment, and filtering the sampled reference voltage value; Storing the filtered reference voltage value after a preset time delay to obtain a delay value; Obtaining the real-time value of the bus voltage at the current moment, and calculating the delay value and the real-time value to obtain the average value of the bus voltage; Performing low-pass filtering on the average value; Selecting the average value through a data selector to output the feedback value of the bus voltage to the power grid; The step of selecting the average value through a data selector to output the feedback value of the bus voltage to the power grid includes: Obtaining the feedback value as a compensation and error correction amount; Dynamically adjusting the average value after low-pass filtering according to the compensation and error correction amount to obtain a final average value; Passing the final average value through a data selector to optimize the selection of slow stable signals and fast mutation signals, and outputting the feedback value of the bus voltage to the power grid; The step of obtaining the feedback value as a compensation and error correction amount includes: Comparing the feedback value with the filtered real-time value, and rejecting it if the difference between the filtered real-time value and the feedback value is obvious, so as to retain the second real-time value close to the feedback value.

2. The integral grid-connected control method according to claim 1, wherein The step of obtaining the real-time value of the current bus voltage and calculating the delay value and the real-time value to obtain the average value of the bus voltage includes: Obtaining the real-time value of the current bus voltage; Subtracting the real-time value from the delay value to obtain a difference; Performing an integration operation on the difference as an integration cumulative amount to obtain the average value of the bus voltage.

3. The integral grid-connected control method according to claim 1, wherein The sampling frequency of the real-time value is twice the control frequency of the grid-connected inverter control.

4. The integral grid-connected control method according to any one of claims 1 to 3, characterized in that The preset time is half a cycle.

5. The integral grid-connected control method according to any one of claims 1 to 3, characterized in that Also including: Forming a control current through voltage loop control of the set value of the bus voltage and the feedback value; Sampling the inductor current and performing current prediction to obtain a predicted current; Superposing the predicted current and the control current and outputting them to the current loop; The current loop adjusts the predicted current and the control current to output a grid-connected current to the single-phase inverter; The single-phase inverter converts the grid-connected current into direct current and outputs it to the power grid.

6. An integral grid-connected control system, characterized in that, Including: A sampling module for collecting the reference voltage value of the bus voltage at the previous moment and the real-time value at the current moment; A first filtering module for filtering the reference voltage value; A delay storage module for storing the reference voltage value after a preset time delay to obtain a delay value; A data processing module for calculating the real-time value and the delay value to obtain the average value of the bus voltage; A data selector for selecting the average value to output a feedback value to the power grid; The step of selecting the average value to output a feedback value to the power grid includes: Obtaining the feedback value as a compensation and error correction amount; Dynamically adjusting the average value after low-pass filtering according to the compensation and error correction amount to obtain a final average value; The final average value is optimized and selected for slow stable signals and fast mutation signals through a data selector, so as to output the feedback value of the bus voltage to the power grid; Obtaining the feedback value as a compensation and error correction amount includes: Comparing the feedback value with the filtered real-time value, and if there is an obvious gap between the filtered real-time value and the feedback value, it is excluded to retain the second real-time value close to the feedback value; A second filtering module is configured to perform low-frequency filtering on the average value and output the average value to the data selector.

7. An integral grid-connected control system according to claim 6, wherein It further includes: A driving module is configured to output a driving signal; A conversion module is configured to convert the feedback value of the AC signal into the feedback value of the DC signal according to the driving signal.

8. An integral grid-connected control system according to claim 7, characterized in that, The conversion module is a single-phase grid-connected inverter with an H6 bridge topology.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions for causing a computer to execute an integral grid-connected control method according to any one of claims 1 to 5.

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