Current sampling delay compensation method, device, equipment and medium

Abstract

The invention discloses a current sampling delay compensation method, device, equipment and medium, and the method comprises the steps: controlling a grid-connected converter to output a current according to an initial current reference signal, and carrying out the sampling of the output current of the grid-connected converter, and obtaining a current sampling signal; performing integral operation on the current sampling signal and the initial current reference signal to obtain a phase difference between the initial current sampling signal and the current reference signal; performing compensation adjustment on the initial current reference signal according to the phase difference to obtain a target current reference signal; and controlling the grid-connected converter to output current according to the target current reference signal. According to the invention, the current sampling delay can be effectively compensated, and the performance of the grid-connected inverter is improved.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a current sampling delay compensation method, device, equipment and medium. Background Art

[0002] In the control process of the grid-connected inverter, the current sampling delay is an issue that cannot be ignored. Due to the existence of sampling delay, there will be a phase difference between the actual value of the current and the reference value. This phase difference will cause the center frequency of the current to shift, which will affect the precise compensation of harmonics and ultimately affect the quality of the grid current. In related technologies, a proportional-integral (PI) control strategy is usually used to regulate the current, but in the presence of sampling delay, the effect of the PI control strategy will be greatly reduced. Therefore, how to effectively compensate for the current sampling delay has become a key issue in improving the performance of the grid-connected inverter. Summary of the invention

[0003] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a current sampling delay compensation method, device, equipment and medium, which can effectively compensate for the current sampling delay and improve the performance of the grid-connected inverter.

[0004] In a first aspect, an embodiment of the present invention provides a current sampling delay compensation method, comprising: Controlling the grid-connected converter to output current according to the initial current reference signal, and sampling the output current of the grid-connected converter to obtain a current sampling signal; Performing an integration operation on the current sampling signal and the initial current reference signal to obtain a phase difference between the initial current sampling signal and the current reference signal; According to the phase difference, compensating and adjusting the initial current reference signal to obtain a target current reference signal; The grid-connected converter is controlled to output current according to the target current reference signal.

[0005] The current sampling delay compensation method provided in the embodiment of the present invention has at least the following beneficial effects: by outputting current control according to the initial current reference signal, sampling the output current of the grid-connected inverter to obtain a current sampling signal, and then integrating the initial current reference signal to obtain a phase difference, and then compensating and adjusting the initial current reference signal according to the phase difference to obtain a target current reference signal, the phase synchronization between the actual value of the output current of the grid-connected inverter and the sampled value can be achieved, oscillation is suppressed, and the accuracy of current control is improved. At the same time, the problems of current center frequency offset and inaccurate harmonic compensation caused by sampling delay are avoided, thereby optimizing the performance of the grid-connected inverter, reducing energy loss, improving the quality of the grid current, and ensuring that the grid-connected inverter can operate stably and efficiently under various working conditions.

[0006] In the current sampling delay compensation method provided by the embodiment of the present invention, sampling the output current of the grid-connected converter to obtain a current sampling signal includes: Sampling the output current of the grid-connected converter to obtain a sampled current; The initial current reference signal is used as a basic signal, the sampling current and the phase angle variable caused by the current sampling delay are introduced to obtain a current sampling signal.

[0007] In the current sampling delay compensation method provided by the embodiment of the present invention, the integration operation of the current sampling signal and the initial current reference signal to obtain the phase difference between the initial current sampling signal and the current reference signal includes: Performing a product operation on the current sampling signal and the initial current reference signal to obtain a current product signal; An integration operation is performed on the current product signal to obtain a phase difference between the initial current sampling signal and the current reference signal.

[0008] In the current sampling delay compensation method provided by an embodiment of the present invention, the current product signal includes a first product signal and a second product signal, the first product signal is constructed by the current sampling signal and the initial current reference signal, and the second product signal is constructed by the complementary signal of the initial current reference signal and the current sampling signal; The integrating operation on the current product signal to obtain a phase difference between the initial current sampling signal and the current reference signal includes: Performing integration operations on the first product signal and the second product signal respectively to obtain a first integrated signal of the first product signal and a second integrated signal of the second product signal; A phase difference between the initial current sampling signal and the current reference signal is obtained according to the first integrated signal and the second integrated signal.

[0009] In the current sampling delay compensation method provided by the embodiment of the present invention, obtaining the phase difference between the initial current sampling signal and the current reference signal according to the first integrated signal and the second integrated signal includes: Using trigonometric functions to perform simplified operations on the first integrated signal and the second integrated signal respectively, to obtain a first simplified signal of the first integrated signal and a second simplified signal of the second integrated signal; A phase difference between the initial current sampling signal and the current reference signal is obtained according to the first simplified signal and the second simplified signal.

[0010] In the current sampling delay compensation method provided by the embodiment of the present invention, the initial current reference signal is compensated and adjusted according to the phase difference to obtain a target current reference signal, including: Performing proportional integration processing on the phase difference to obtain a compensation phase angle; According to the compensation phase angle, the phase of the initial current reference signal is compensated and adjusted to obtain a target current reference signal.

[0011] In the current sampling delay compensation method provided by the embodiment of the present invention, the phase of the initial current reference signal is compensated and adjusted according to the compensation phase angle to obtain the target current reference signal, including: Converting the initial current reference signal into a reference complex signal, and constructing a complex signal using the compensation phase angle as a signal argument to obtain a compensated complex signal; The reference complex signal is multiplied by the compensated complex signal to obtain a target current reference signal.

[0012] In the current sampling delay compensation method provided by the embodiment of the present invention, after controlling the grid-connected converter to output current according to the target current reference signal, the method further includes: Sampling the output current of the grid-connected converter again to obtain a new sampled current; According to the new sampled current, the target current reference signal is adjusted to update the target current reference signal; The grid-connected converter is controlled to output current according to the updated target current reference signal.

[0013] In the current sampling delay compensation method provided by the embodiment of the present invention, adjusting the target current reference signal according to the new sampling current to update the target current reference signal includes: Extracting a reference current synchronized with a sampling time of the new sampled current from the target current reference signal; According to the current difference between the new sampled current and the reference current, the target current reference signal is adjusted to update the target current reference signal to reduce the current difference. In a second aspect, an embodiment of the present invention provides an operation control device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the current sampling delay compensation method as described in the embodiment of the first aspect above.

[0014] The operation control device provided in the embodiment of the present invention has at least the following beneficial effects: by outputting current control according to the initial current reference signal, sampling the output current of the grid-connected inverter to obtain a current sampling signal, and then integrating the initial current reference signal to obtain a phase difference, and then compensating and adjusting the initial current reference signal according to the phase difference to obtain a target current reference signal, the phase synchronization between the actual value of the output current of the grid-connected inverter and the sampling value can be achieved, oscillation is suppressed, and the accuracy of current control is improved. At the same time, the problems of current center frequency offset and inaccurate harmonic compensation caused by sampling delay are avoided as much as possible, thereby optimizing the performance of the grid-connected inverter, reducing energy loss, improving the quality of grid current, and ensuring that the grid-connected inverter can operate stably and efficiently under various working conditions.

[0015] In a third aspect, an embodiment of the present invention provides a current sampling delay compensation device, comprising an operation control device as described in the embodiment of the second aspect above.

[0016] The current sampling delay compensation device provided in accordance with the embodiment of the present invention has at least the following beneficial effects: by outputting current control according to the initial current reference signal, sampling the output current of the grid-connected inverter to obtain a current sampling signal, and then integrating the initial current reference signal to obtain a phase difference, and then compensating and adjusting the initial current reference signal according to the phase difference to obtain a target current reference signal, the phase synchronization between the actual value of the output current of the grid-connected inverter and the sampled value can be achieved, oscillation can be suppressed, and the accuracy of current control can be improved. At the same time, the problems of current center frequency offset and inaccurate harmonic compensation caused by sampling delay can be avoided as much as possible, thereby optimizing the performance of the grid-connected inverter, reducing energy loss, improving the quality of the grid current, and ensuring that the grid-connected inverter can operate stably and efficiently under various working conditions.

[0017] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the current sampling delay compensation method as described in the embodiment of the first aspect.

[0018] The computer-readable storage medium provided in accordance with the embodiment of the present invention has at least the following beneficial effects: by outputting current control according to an initial current reference signal, sampling the output current of the grid-connected inverter to obtain a current sampling signal, and then integrating the current with the initial current reference signal to obtain a phase difference, and then compensating and adjusting the initial current reference signal according to the phase difference to obtain a target current reference signal, the phase synchronization between the actual value of the output current of the grid-connected inverter and the sampling value can be achieved, oscillation can be suppressed, and the accuracy of current control can be improved. At the same time, the problems of current center frequency offset and inaccurate harmonic compensation caused by sampling delay can be avoided as much as possible, thereby optimizing the performance of the grid-connected inverter, reducing energy loss, improving the quality of the grid current, and ensuring that the grid-connected inverter can operate stably and efficiently under various working conditions.

[0019] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0021] The present invention is further described below in conjunction with the accompanying drawings and embodiments; Figure 1 is a flow chart of a current sampling delay method provided by an embodiment of the present invention; Figure 2 yes Figure 1 The specific process schematic diagram of step S110 is shown; Figure 3 yes Figure 1 The specific process schematic diagram of step S120 is shown; Figure 4 yes Figure 3 The specific process schematic diagram of step S320 is shown; Figure 5 yes Figure 1 The specific process schematic diagram of step S130 is shown; Figure 6is a flowchart of a current sampling delay compensation process provided by an embodiment of the present invention; Figure 7 yes Figure 5 The specific process schematic diagram of step S520 is shown; Figure 8 yes Figure 1 The specific process schematic diagram of step S140 is shown; Fig. 9 yes Figure 8 The specific process diagram of step S730 is shown; Fig.10 It is a structural schematic diagram of the operation control device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0022] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0023] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, "above", "below", "within", etc. are understood to include the number itself, "any one" means one or more, "at least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. If there is a description of the first and the second, it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0024] It should be noted that the terms such as setting, installing, and connecting in the embodiments of the present invention should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the embodiments of the present invention in combination with the specific content of the technical solution. For example, the term "connection" can be a mechanical connection, an electrical connection, or mutual communication; it can be directly connected or indirectly connected through an intermediate medium.

[0025] It should be noted that the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] In the control process of the grid-connected inverter, the current sampling delay is an issue that cannot be ignored. Due to the existence of sampling delay, there will be a phase difference between the actual value of the current and the reference value. This phase difference will cause the center frequency of the current to shift, which will affect the precise compensation of harmonics and ultimately affect the quality of the grid current. In related technologies, a proportional-integral (PI) control strategy is usually used to regulate the current, but in the presence of sampling delay, the effect of the PI control strategy will be greatly reduced. Therefore, how to effectively compensate for the current sampling delay has become a key issue in improving the performance of the grid-connected inverter.

[0027] Based on this, an embodiment of the present invention proposes a current sampling delay method, device, equipment and medium, which outputs current control according to an initial current reference signal, samples the output current of the grid-connected inverter to obtain a current sampling signal, and then integrates the initial current reference signal to obtain a phase difference, and then compensates and adjusts the initial current reference signal according to the phase difference to obtain a target current reference signal. This can achieve phase synchronization between the actual value of the output current of the grid-connected inverter and the sampled value, suppress oscillation, and improve the accuracy of current control. At the same time, it can avoid the current center frequency offset and inaccurate harmonic compensation caused by sampling delay as much as possible, thereby optimizing the performance of the grid-connected inverter, reducing energy loss, improving the quality of the grid current, and ensuring that the grid-connected inverter can operate stably and efficiently under various working conditions.

[0028] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0029] First, refer to Figure 1 , Figure 1 : is a flow chart of a current sampling delay method provided by an embodiment of the present invention. The current sampling delay compensation method includes but is not limited to the following steps: Step S110: controlling the grid-connected converter to output current according to the initial current reference signal, and sampling the output current of the grid-connected converter to obtain a current sampling signal; Step S120: performing an integration operation on the current sampling signal and the initial current reference signal to obtain a phase difference between the initial current sampling signal and the current reference signal; Step S130: compensating and adjusting the initial current reference signal according to the phase difference to obtain a target current reference signal; Step S140: controlling the grid-connected converter to output current according to the target current reference signal.

[0030] It can be understood that the initial current reference signal can be set based on comprehensive considerations such as grid demand, load conditions, and performance parameters of the grid-connected converter. The initial current reference signal can refer to the current value output by the voltage outer loop in the dual-loop control of the grid-connected converter. The initial current reference signal can be a sine wave signal. Since the grid-connected converter is controlled to output current according to the set initial current reference signal, at this time, the current actually output by the grid-connected converter can be understood as the initial current reference signal.

[0031] The output current information of the grid-connected converter, i.e., the current sampling signal, is obtained. The current sampling signal can be obtained by real-time acquisition through measuring equipment such as current sensors. However, due to the sampling delay, the sampled data is actually the actual output data of the grid-connected converter before a certain period of time. Therefore, the current sampling signal can reflect the current output of the grid-connected converter at a historical moment. Therefore, there is a time delay between the initial current reference signal (or the actual output current signal) and the current sampling signal. The current sampling signal cannot accurately and timely reflect the current data output by the current grid-connected converter in real time. That is to say, the delay between the current sampling signal and the initial current reference signal is ignored in the related technology, and the initial current reference signal, i.e., the output current, is adjusted directly according to the current sampling signal. The adjustment based on the current sampling signal with sampling delay will cause the waveform of the output current to be inconsistent with the actual demand and produce distortion. This distortion may be manifested as a phase shift, amplitude change, or increase in harmonic components of the current waveform, affecting the stability of the control system of the grid-connected converter.

[0032] After obtaining the current sampling signal, the initial current reference signal is obtained, and the initial current reference signal and the current sampling signal are integrated, and the initial current reference signal is used as the basis for analysis, wherein the initial current reference signal can be regarded as a standard sine wave, and the phase lead of the current sampling signal relative to the initial current reference signal is analyzed on the initial current reference signal, that is, the phase difference between the current sampling signal and the initial current reference signal is calculated by integration operation. The phase difference calculated by integration operation can reflect the phase relationship between the two signals, and can also reflect the current sampling delay, thereby providing accurate information for subsequent compensation adjustment.

[0033] The phase difference between the current sampling signal and the initial current reference signal is calculated by the integral operation, which can quickly complete the calculation of the phase difference and better adapt to the application scenarios that require real-time signal processing, such as the current phase monitoring in the power system. At the same time, the calculation process of the integral operation is simple, has low hardware dependence, and is easy to implement. In the related technology, the fast Fourier transform (FFT) is usually used to convert the current sampling signal and the initial current reference signal into the frequency domain and extract the phase angle to calculate the phase difference. Although this method can provide high-precision phase information, the calculation process is relatively complex and requires a lot of computing resources and time. Therefore, the method of calculating the phase difference by integral operation is superior to the method of calculating the phase difference by FFT in terms of calculation simplicity and real-time performance, and is more suitable for application scenarios that require fast response and real-time processing. At the same time, the method of calculating the phase difference by integral operation is easier to implement in hardware, reducing system complexity and cost.

[0034] After obtaining the phase difference, the phase difference can be used to compensate and adjust the initial current reference current. The purpose of compensation adjustment is to eliminate the phase difference, so that the initial current reference signal (i.e., output current) of the grid-connected converter is phase-synchronized with the current sampling signal. By adjusting the phase of the initial current reference signal, a new target current reference signal can be obtained. The target current reference signal can be closer to the current sampling signal, which helps to eliminate the phase difference between the actual output value and the sampling value of the current, so that real-time and accurate current data can be obtained, which helps to achieve accurate compensation for harmonics in the current and improve the quality of the grid current. Therefore, making the grid-connected converter output current according to the target current reference signal can ensure that the output current of the grid-connected converter is consistent with the sampling current, achieve phase synchronization between the actual value of the current and the sampling value, help improve the quality and stability of the grid current, and can also reduce the loss and failure rate of the grid-connected converter, and improve the operating efficiency of the entire power system.

[0035] Reference Figure 2 , a current sampling delay compensation method provided by an embodiment of the present invention, Figure 1 In the step S110 shown, the current sampling delay compensation method further includes steps S210 to S220: Step S210: sampling the output current of the grid-connected converter to obtain a sampled current; Step S220: Taking the initial current reference signal as a basic signal, introducing the sampling current and the phase angle variable caused by the current sampling delay, and obtaining a current sampling signal.

[0036] It is understandable that in the process of the grid-connected converter outputting current to the grid according to the control instruction, the current sensor and other measuring equipment can be used to sample the output current of the grid-connected converter in real time. The current value obtained by sampling is the sampling current. However, due to the sampling delay, the obtained sampling current reflects the actual output current of the grid-connected converter at the historical moment, which is inconsistent with the actual output current of the grid-connected converter at the current moment (that is, the initial current reference signal). In other words, there will be a phase difference between the sampled current signal and the actual output current signal. This phase difference can be expressed as a phase angle variable, which reflects the influence of the sampling delay on the phase of the current signal. The initial current reference signal can be used as a basic signal. The initial current reference signal The specific expression of can refer to formula (1): (1); Among them, the initial current reference signal For a sine wave signal, the phase angle The amplitude and value are set according to the grid demand. Here, the amplitude is 1 as an example. The initial current reference signal The expected grid-connected current waveform can be expressed. The sampling current and phase angle variables are introduced into the basic signal to construct the current sampling signal. The specific expression of can refer to formula (2): (2); in, Indicates the normal phase angle, which is the initial current reference signal The phase angle in is known to the control system, and Then, the actual current sampling signal can be expressed as Compared with the ideal current sampling signal (i.e. the initial current reference signal ) can be compared and analyzed to determine the accuracy of the current current sampling, thereby judging whether there is a delay in the sampling process. By analyzing the difference between the current sampling signal and the initial current reference signal, the output current of the grid-connected converter, i.e., the initial current reference signal, can be adjusted to reduce the current difference, thereby facilitating accurate current control, reducing the current fluctuation and harmonic components in the power grid, improving the power factor, and thus improving the stability and reliability of the power system.

[0037] Reference Figure 3 , a current sampling delay compensation method provided by an embodiment of the present invention, Figure 1 In step S120 shown, the current sampling delay compensation method further includes steps S310 to S320: Step S310: performing a product operation on the current sampling signal and the initial current reference signal to obtain a current product signal; Step S320: performing an integration operation on the current product signal to obtain a phase difference between the initial current sampling signal and the current reference signal.

[0038] Specifically, the analysis process of the current sampling signal and the initial current reference signal may refer to the analysis of the initial current reference signal and the phase shift angle (i.e., the phase angle variable ) current sampling signal, and then integrate the product result to calculate the phase shift angle. The calculation process can refer to formula (3): (3); Among them, the two current signals can be multiplied, and the result of this product operation is the current product signal The phase difference between the initial current reference signal and the current sampling signal is the phase angle variable introduced by the current sampling signal during sampling. Therefore, by integrating the current product signal, the introduced current sampling delay is analyzed.

[0039] It can be understood that the result of the integration operation is a time-dependent cumulative value, which can reflect the phase relationship between the current sampling signal and the initial current reference signal over a period of time. Due to the periodicity of the sinusoidal wave signal (i.e., the initial current reference signal), the result of the integration operation will show periodic changes. Therefore, by analyzing the result of the integration operation, the phase difference between the current sampling signal and the initial current reference signal can be determined.

[0040] Reference Figure 4 , a current sampling delay compensation method provided by an embodiment of the present invention, Figure 3 In step S320 shown, the current sampling delay compensation method further includes steps S410 to S430: Step S410: performing integration operations on the first product signal and the second product signal respectively to obtain a first integrated signal of the first product signal and a second integrated signal of the second product signal; Step S420: using a trigonometric function to perform simplification operations on the first integrated signal and the second integrated signal respectively, to obtain a first simplified signal of the first integrated signal and a second simplified signal of the second integrated signal; Step S430: Obtaining a phase difference between the initial current sampling signal and the current reference signal according to the first simplified signal and the second simplified signal.

[0041] It can be understood that the current product signal includes a first product signal and a second product signal, and the first product signal is the product result of the current sampling signal and the initial current reference signal. , performing an integration operation on the first product signal, the first integral signal can be obtained, that is, Then, the first integrated signal is simplified by using trigonometric functions to obtain a first simplified signal. The simplified operation process of the first integrated signal can be specifically referred to the following formulas (4) and (5): (4); Based on the product formula of trigonometric functions, the first integral signal can be expanded and transformed. Then, the expanded first expression, i.e., formula (4), can be integrated within one cycle, and considering The integral result of will be offset due to periodicity, that is, it will be zero within one cycle. Therefore, the first integral signal can be simplified to obtain the first simplified signal. The expression of the first simplified signal can refer to formula (5): (5); Therefore, by performing simplified operations on the first integrated signal, a related quantity of the phase angle variable, ie, the first simplified signal, can be obtained.

[0042] To solve the phase angle variable, the complementary signal of the initial current reference signal can be used With current sampling signal Multiply to get the second product signal, further derive the correlation of the phase angle variable, and use the correlation of multiple phase angle variables to solve. Specifically, the second product signal The expression of can refer to formula (6): (6); Similarly, the second product signal is integrated to obtain the corresponding second integrated signal, that is, ; Then, the second integral signal is expanded using the product formula of trigonometric functions to obtain the expanded second expression, which can refer to formula (7): (7); In one cycle The integral result is zero. Therefore, the second simplified signal can be obtained by simplifying the second expression. The expression of the second simplified signal can refer to formula (8): (8); After obtaining the first simplified signal and the second simplified signal, the phase angle variable, that is, the phase difference between the initial current sampling signal and the current reference signal, can be calculated by an inverse trigonometric function. Specifically, the first simplified signal and the second simplified signal are converted into corresponding formulas (9) and (10), respectively: (9); (10); That is to say, by transforming the first simplified signal, the phase angle variable can be obtained. The cosine correlation of , and by transforming the second simplified signal, the phase angle variable can be obtained The sinusoidal correlation Then, the phase difference between the initial current sampling signal and the current reference signal can be solved by using the inverse trigonometric function. The specific phase difference can refer to formula (11): (11); Among them, the phase difference is the phase angle variable introduced by the current sampling delay .

[0043] Reference Figure 5 , a current sampling delay compensation method provided by an embodiment of the present invention, Figure 1 In step S130 shown, the current sampling delay compensation method further includes steps S510 to S520: Step S510: performing proportional integration processing on the phase difference to obtain a compensation phase angle; Step S520: compensating and adjusting the phase of the initial current reference signal according to the compensation phase angle to obtain a target current reference signal.

[0044] Reference Figure 6 , Figure 6 The flow chart of the current sampling delay compensation process provided by the embodiment of the present invention is as follows: the sampling current obtained by sampling the output current of the grid-connected converter is input into the phase controller for integration operation, and the phase difference can be obtained. After the phase difference is calculated, the phase difference, i.e., the phase angle variable The initial current reference signal is compensated so that there is no phase difference between the compensated initial current reference signal and the current sampling signal. Figure 6 As shown, the phase difference can be input into the proportional-integral controller for proportional-integral processing, and the compensation phase angle for compensating and adjusting the initial current reference signal can be obtained. The initial current reference signal can be phase-compensated by using the compensation phase angle, and the phase difference between the initial current reference signal and the current sampling signal can be gradually reduced until it is eliminated, so that the current sampling value and the actual output value are consistent in phase. By performing proportional-integral processing on the phase difference, a smooth transition of phase compensation can be achieved, avoiding system instability caused by sudden changes in the compensation amount.

[0045] Reference Figure 7 , a current sampling delay compensation method provided by an embodiment of the present invention, Figure 5In step S520 shown, the current sampling delay compensation method further includes steps S610 to S620: Step S610: converting the initial current reference signal into a reference complex signal, and constructing a complex signal using the compensation phase angle as the signal argument to obtain a compensated complex signal; Step S620 : multiplying the reference complex signal and the compensated complex signal to obtain a target current reference signal.

[0046] It should be noted that in the process of using the compensation phase angle to perform phase compensation on the initial current reference signal, the phase rotation method can be used to compensate for the phase difference. Specifically, the initial current reference signal is first converted into a reference complex signal in complex form. If the initial current reference signal is a real signal, the initial current reference signal can be regarded as a complex signal with an imaginary part of zero; then a complex signal related to the compensation phase angle is constructed, the modulus of the complex signal is set to 1, and the signal angle is consistent with the compensation phase angle, so as to obtain a compensated complex signal corresponding to the compensation phase angle; then, the compensated complex signal is multiplied by the reference complex signal, and the target current reference signal after phase compensation can be obtained. Among them, after the two complex signals are multiplied, the product result may be a complex signal, so the real part of the product result can be extracted as the target current reference signal.

[0047] After obtaining the target current reference signal, the grid-connected converter can be controlled to output current according to the target current reference signal. At this time, since the phase difference is eliminated, the actual current output of the grid-connected converter will approach the current sampling value, that is, the current sampling value of the grid-connected converter is consistent with the actual output value in phase, which effectively compensates for the current sampling delay, thereby improving the quality of the grid current.

[0048] Reference Figure 8 , a current sampling delay compensation method provided by an embodiment of the present invention, Figure 1 After step S140, the current sampling delay compensation method further includes steps S710 to S730: Step S710: sampling the output current of the grid-connected converter again to obtain a new sampled current; Step S720: adjusting the target current reference signal according to the new sampled current to update the target current reference signal; Step S730: controlling the grid-connected converter to output current according to the updated target current reference signal.

[0049] It can be understood that after adjusting the current output of the grid-connected converter, the output current of the grid-connected converter can be sampled to determine whether the adjusted output current is consistent with the sampled current, and the difference between the two is found. The target current reference signal is then adjusted using the difference to implement feedback adjustment and closed-loop control of the target current reference signal, update the target current reference signal, and control the grid-connected converter to output current according to the updated target current reference signal, hoping that the updated target current reference signal can be consistent in phase with the new sampled current.

[0050] Reference Fig. 9 , a current sampling delay compensation method provided by an embodiment of the present invention, Figure 8 In step S730 shown, the current sampling delay compensation method further includes steps S810 to S820: Step S810: extracting a reference current synchronized with a sampling time of a new sampled current from a target current reference signal; Step S820: adjusting the target current reference signal according to the current difference between the new sampled current and the reference current, and updating the target current reference signal.

[0051] While sampling the output current of the grid-connected converter, the reference current is synchronously extracted from the target current reference signal, that is, the sampling time of the output current of the grid-connected converter is recorded, and then the current value corresponding to the sampling time is extracted from the target current reference signal to obtain the reference current. Next, the new sampled current is differenced with the reference current to obtain the current difference, and then the target current reference signal is adjusted according to the current difference to reduce the current difference, that is, the target current reference signal is consistent with the current sampled current. Specifically, in the case where the current difference between the new sampled current and the reference current is used to adjust the target reference current signal, proportional resonant (PR) control can be used. PR control is a special control strategy that can be applied to AC systems that require precise control of a specific frequency (or resonant frequency), such as current control in grid-connected converters. Figure 6As shown, in the current sampling delay compensation method, the new sampled current and the reference current can be input into the PR controller. When there is a difference between the new sampled current and the reference current, the PR controller can calculate the adjustment amount according to the difference. Specifically, the PR controller detects the frequency component of the current difference signal, and pays special attention to the component corresponding to the resonant frequency. When the frequency of the difference signal is close to the resonant frequency, the gain of the PR controller increases significantly, thereby providing a larger adjustment amount to reduce the difference. Then, the adjustment amount output by the PR controller is superimposed on the original target current reference signal to obtain an updated target current reference signal, and then the updated target current reference signal is used to control the output current of the grid-connected converter.

[0052] Second, refer to Fig.10 The embodiment of the present invention provides an operation control device 1000, including a memory 1020, a processor 1010, and a computer program stored in the memory 1020 and executable on the processor 1010. The processor 1010 executes the program to implement the current sampling delay compensation method of the first embodiment, for example, Figure 1 In the method steps S110 to S140, Figure 2 Steps S210 to S220 of the method, or performing Figure 3 Steps S310 to S320 of the method, or performing Figure 4 or performing steps S410 to S430 of the method Figure 5 Steps S510 to S520 of the method, or executing Figure 7 Steps S610 to S620 of the method, or performing Figure 8 or performing steps S710 to S730 of the method Fig. 9 Method steps S810 to S820 in.

[0053] According to the operation control device provided by the embodiment of the present invention, the output current control is performed according to the initial current reference signal, and the output current of the grid-connected inverter is sampled to obtain a current sampling signal, and then an integral operation is performed with the initial current reference signal to obtain a phase difference, and then the initial current reference signal is compensated and adjusted according to the phase difference to obtain a target current reference signal. The phase synchronization between the actual value and the sampled value of the output current of the grid-connected inverter can be achieved, the oscillation is suppressed, and the accuracy of the current control is improved. At the same time, the problems of current center frequency offset and inaccurate harmonic compensation caused by sampling delay are avoided as much as possible, thereby optimizing the performance of the grid-connected inverter, reducing energy loss, improving the quality of the grid current, and ensuring that the grid-connected inverter can operate stably and efficiently under various working conditions.

[0054] In a third aspect, an embodiment of the present invention provides a current sampling delay compensation device, comprising an operation control device as described in the embodiment of the second aspect above.

[0055] According to the current sampling delay compensation device provided by the embodiment of the present invention, the output current control is performed according to the initial current reference signal, and the output current of the grid-connected inverter is sampled to obtain a current sampling signal, and then an integral operation is performed with the initial current reference signal to obtain a phase difference, and then the initial current reference signal is compensated and adjusted according to the phase difference to obtain a target current reference signal. The phase synchronization between the actual value and the sampled value of the output current of the grid-connected inverter can be achieved, oscillation is suppressed, and the accuracy of current control is improved. At the same time, the problems of current center frequency offset and inaccurate harmonic compensation caused by sampling delay are avoided as much as possible, thereby optimizing the performance of the grid-connected inverter, reducing energy loss, improving the quality of the grid current, and ensuring that the grid-connected inverter can operate stably and efficiently under various working conditions.

[0056] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the current sampling delay compensation method of the first aspect embodiment above, for example, to execute Figure 1 In the method steps S110 to S140, Figure 2 Steps S210 to S220 of the method, or performing Figure 3 Steps S310 to S320 of the method, or performing Figure 4 or performing steps S410 to S430 of the method Figure 5 Steps S510 to S520 of the method, or executing Figure 7 Steps S610 to S620 of the method, or performing Figure 8 or performing steps S710 to S730 of the method Fig. 9 Method steps S810 to S820 in.

[0057] According to the computer-readable storage medium provided in the embodiment of the present invention, by outputting current control according to the initial current reference signal, sampling the output current of the grid-connected inverter to obtain a current sampling signal, and then integrating the initial current reference signal to obtain a phase difference, and then compensating and adjusting the initial current reference signal according to the phase difference to obtain a target current reference signal, the phase synchronization between the actual value of the output current of the grid-connected inverter and the sampling value can be achieved, oscillation is suppressed, and the accuracy of current control is improved. At the same time, the problems of current center frequency offset and inaccurate harmonic compensation caused by sampling delay are avoided as much as possible, thereby optimizing the performance of the grid-connected inverter, reducing energy loss, improving the quality of grid current, and ensuring that the grid-connected inverter can operate stably and efficiently under various working conditions.

[0058] It will be appreciated by those skilled in the art that all or some of the steps and systems in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. Some physical components or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or may be implemented as hardware, or may be implemented as an integrated circuit, such as an application-specific integrated circuit. The integrated physical components may be stored in a computer-readable storage medium if implemented in the form of software functional units and sold or used as independent products. Based on such an understanding, the technical solution of the present invention may be essentially or partly or all or partly in the form of a software product that contributes to the prior art, and the computer software product may be stored in a storage medium, including several instructions for enabling a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of various embodiments of the present invention. As a term well known to those skilled in the art, computer storage media include 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 include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk DVD or other optical disk storage, magnetic cassettes, magnetic 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 skilled 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 transport mechanism, and may include any information delivery media.

Claims

1. A current sampling delay compensation method, characterized in that: include: Controlling the grid-connected converter to output current according to the initial current reference signal, and sampling the output current of the grid-connected converter to obtain a current sampling signal; Performing an integration operation on the current sampling signal and the initial current reference signal to obtain a phase difference between the initial current sampling signal and the current reference signal; According to the phase difference, compensating and adjusting the initial current reference signal to obtain a target current reference signal; The grid-connected converter is controlled to output current according to the target current reference signal.

2. The current sampling delay compensation method according to claim 1, characterized in that: The step of sampling the output current of the grid-connected converter to obtain a current sampling signal includes: Sampling the output current of the grid-connected converter to obtain a sampled current; The initial current reference signal is used as a basic signal, the sampling current and the phase angle variable caused by the current sampling delay are introduced to obtain a current sampling signal.

3. The current sampling delay compensation method according to claim 1, characterized in that: The integrating operation of the current sampling signal and the initial current reference signal to obtain a phase difference between the initial current sampling signal and the current reference signal includes: Performing a product operation on the current sampling signal and the initial current reference signal to obtain a current product signal; An integration operation is performed on the current product signal to obtain a phase difference between the initial current sampling signal and the current reference signal.

4. The current sampling delay compensation method according to claim 3, characterized in that: The current product signal includes a first product signal and a second product signal, the first product signal is constructed by the current sampling signal and the initial current reference signal, and the second product signal is constructed by the complementary signal of the initial current reference signal and the current sampling signal; The integrating operation on the current product signal to obtain a phase difference between the initial current sampling signal and the current reference signal includes: Performing integration operations on the first product signal and the second product signal respectively to obtain a first integrated signal of the first product signal and a second integrated signal of the second product signal; A phase difference between the initial current sampling signal and the current reference signal is obtained according to the first integrated signal and the second integrated signal.

5. The current sampling delay compensation method according to claim 4, characterized in that: The step of obtaining a phase difference between the initial current sampling signal and the current reference signal according to the first integrated signal and the second integrated signal includes: Using trigonometric functions to perform simplified operations on the first integrated signal and the second integrated signal respectively, to obtain a first simplified signal of the first integrated signal and a second simplified signal of the second integrated signal; A phase difference between the initial current sampling signal and the current reference signal is obtained according to the first simplified signal and the second simplified signal.

6. The current sampling delay compensation method according to claim 1, characterized in that: The compensating and adjusting the initial current reference signal according to the phase difference to obtain a target current reference signal includes: Performing proportional integration processing on the phase difference to obtain a compensation phase angle; According to the compensation phase angle, the phase of the initial current reference signal is compensated and adjusted to obtain a target current reference signal.

7. The current sampling delay compensation method according to claim 6, characterized in that: The compensating and adjusting the phase of the initial current reference signal according to the compensation phase angle to obtain a target current reference signal includes: Converting the initial current reference signal into a reference complex signal, and constructing a complex signal using the compensation phase angle as a signal argument to obtain a compensated complex signal; The reference complex signal is multiplied by the compensated complex signal to obtain a target current reference signal.

8. The current sampling delay compensation method according to claim 1, characterized in that: After controlling the grid-connected converter to output current according to the target current reference signal, the method further includes: Sampling the output current of the grid-connected converter again to obtain a new sampled current; According to the new sampled current, the target current reference signal is adjusted to update the target current reference signal; The grid-connected converter is controlled to output current according to the updated target current reference signal.

9. The current sampling delay compensation method according to claim 8, characterized in that: The step of adjusting the target current reference signal according to the new sampled current to update the target current reference signal includes: Extracting a reference current synchronized with a sampling time of the new sampled current from the target current reference signal; According to the current difference between the new sampled current and the reference current, the target current reference signal is adjusted and updated to reduce the current difference.

10. An operation control device, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the current sampling delay compensation method according to any one of claims 1 to 9.

11. A current sampling delay compensation device, applied to a converter system, characterized in that: It comprises the operation control device as claimed in claim 10.

12. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the current sampling delay compensation method according to any one of claims 1 to 9.

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