Power grid voltage frequency detection method, system and equipment

Abstract

The invention is suitable for the technical field of power systems, and provides a power grid voltage frequency detection method, system and equipment, and the method comprises the steps: obtaining a current input voltage signal of a power grid voltage in a current sampling period and a feedback voltage signal corresponding to a previous input voltage signal in a previous sampling period; obtaining a to-be-separated voltage signal of the current sampling period according to the current input voltage signal and the feedback voltage signal; performing positive and negative sequence voltage separation on the to-be-separated voltage signal to obtain a current positive sequence fundamental component and a current negative sequence fundamental component of the current sampling period; and performing signal processing on the to-be-separated voltage signal of the current sampling period and the current positive sequence fundamental component to obtain the power grid frequency of the current sampling period in the power grid voltage so as to perform closed-loop feedback control of the next sampling period according to the power grid frequency of the current sampling period, the current positive sequence fundamental component and the current negative sequence fundamental component. Real-time tracking of the power grid frequency is realized, and the accuracy of frequency detection is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of power systems, and in particular, relates to a method, system and device for detecting power grid voltage and frequency. Background Art

[0002] The voltage frequency in the power grid system is one of the most important indicators of power quality. Generally, the grid voltage frequency is required to be within the range of ±0.5Hz. However, when the active and reactive power of the power system is dynamically balanced, such as the investment of a large number of distributed new energy power generation equipment and the access of large nonlinear loads, the actual frequency of the grid voltage will fluctuate greatly.

[0003] When abnormal faults such as imbalance, frequency mutation, and large-scale harmonic injection occur in the power grid, the traditional method for detecting the grid voltage frequency is to detect it through Park transformation (abc-dq coordinate transformation). This method has a good effect under the condition of symmetrical grid voltage. However, under the condition of asymmetric grid voltage, since the grid voltage contains a large number of double-frequency harmonics, the grid voltage frequency detection is inaccurate and the frequency locking effect is very poor. Summary of the invention

[0004] The embodiments of the present application provide a grid voltage frequency detection method, system and device, which can solve the problem that the traditional grid voltage frequency detection method has inaccurate grid voltage frequency detection and poor frequency locking effect accuracy due to the presence of a large number of double frequency harmonics under unbalanced grid conditions.

[0005] In a first aspect, an embodiment of the present application provides a method for detecting a voltage frequency of a power grid, the method comprising:

[0006] Acquire a feedback voltage signal corresponding to a current input voltage signal of the grid voltage in a current sampling period and a previous input voltage signal in a previous sampling period, wherein the feedback voltage signal includes a previous positive sequence fundamental component and a previous negative sequence fundamental component;

[0007] Obtaining the voltage signal to be separated in the current sampling period according to the current input voltage signal and the feedback voltage signal;

[0008] Performing positive-sequence and negative-sequence voltage separation on the voltage signal to be separated to obtain a current positive-sequence fundamental component and a current negative-sequence fundamental component of the current sampling period;

[0009] Signal processing is performed on the voltage signal to be separated and the current positive-sequence fundamental component of the current sampling period to obtain the grid frequency of the current sampling period in the grid voltage, so as to perform closed-loop feedback control of the next sampling period according to the grid frequency of the current sampling period, the current positive-sequence fundamental component, and the current negative-sequence fundamental component.

[0010] In a possible implementation manner of the first aspect, the current input voltage signal includes a current first input voltage signal and a current second input voltage signal, the previous positive-sequence fundamental component includes a previous first positive-sequence fundamental component and a previous second positive-sequence fundamental component, and the previous negative-sequence fundamental component includes a previous first negative-sequence fundamental component and a previous second negative-sequence fundamental component;

[0011] The step of obtaining the voltage signal to be separated in the current sampling period according to the current input voltage signal and the feedback voltage signal includes:

[0012] Performing difference calculation on a previous first fundamental wave output signal obtained by adding the previous first positive-sequence fundamental wave component and the previous first negative-sequence fundamental wave component and the current first input voltage signal to obtain a first voltage signal to be separated in the current sampling period;

[0013] The difference between the last second fundamental wave output signal obtained by adding the last second positive-sequence fundamental wave component and the last second negative-sequence fundamental wave component and the current second input voltage signal is calculated to obtain the second voltage signal to be separated in the current sampling period.

[0014] In a possible implementation manner of the first aspect, performing positive-sequence and negative-sequence voltage separation on the voltage signal to be separated to obtain a current positive-sequence fundamental component and a current negative-sequence fundamental component of the current sampling period includes:

[0015] Extracting positive-sequence components from the first voltage signal to be separated and the second voltage signal to be separated to obtain a current first positive-sequence fundamental component and a current second positive-sequence fundamental component;

[0016] Negative-sequence components are extracted from the first voltage signal to be separated and the second voltage signal to be separated to obtain a current first negative-sequence fundamental component and a current second negative-sequence fundamental component.

[0017] In a possible implementation manner of the first aspect, extracting positive-sequence components from the first voltage signal to be separated and the second voltage signal to be separated to obtain a current first positive-sequence fundamental component and a second positive-sequence fundamental component includes:

[0018] Performing a first discrete filtering process based on the difference between the first voltage signal to be separated and the second voltage signal to be separated, and the grid frequency of the last sampling period, to obtain the current first positive-sequence fundamental component;

[0019] A second discrete filtering process is performed based on the sum of the first voltage signal to be separated and the second voltage signal to be separated, and the grid frequency of the previous sampling period to obtain the current second positive-sequence fundamental component.

[0020] In a possible implementation manner of the first aspect, extracting negative-sequence components from the first voltage signal to be separated and the second voltage signal to be separated to obtain a current first negative-sequence fundamental component and a current second negative-sequence fundamental component includes:

[0021] Performing a third discrete filtering process based on the difference between the first voltage signal to be separated, the second voltage signal to be separated, and the grid frequency of the previous sampling period to obtain the current first negative-sequence fundamental component;

[0022] A fourth discrete filtering process is performed based on the sum of the first voltage signal to be separated and the second voltage signal to be separated, and the grid frequency of the previous sampling period to obtain the current second negative-sequence fundamental component.

[0023] In a possible implementation manner of the first aspect, performing signal processing on the voltage signal to be separated and the current positive-sequence fundamental component of the current sampling period to obtain the grid frequency of the current sampling period in the grid voltage includes:

[0024] Performing a first multiplication operation on the first voltage signal to be separated and the current second positive-sequence fundamental component to obtain a first operation output signal;

[0025] Performing a second multiplication operation on the per-unit value of the current sampling period and the first operation output signal to obtain a second operation output signal; the per-unit value is determined based on the current first positive-sequence fundamental component and the current second positive-sequence fundamental component;

[0026] Performing a fifth discrete filtering process based on the second operation output signal to obtain a third operation output signal;

[0027] Based on the third operation output signal and the preset feedforward angular frequency, the grid frequency of the current sampling period in the grid voltage is obtained.

[0028] In a possible implementation manner of the first aspect, the step of determining the per-unit value of the current sampling period includes:

[0029] Based on the square of the current first positive-sequence fundamental component, the square of the current second positive-sequence fundamental component and a preset per-unit parameter, an operation is performed to obtain the per-unit value of the current sampling period.

[0030] In a possible implementation manner of the first aspect, performing fifth discrete filtering based on the second operation output signal to obtain a third operation output signal includes:

[0031] Amplifying the second operation output signal based on a preset multiple to obtain an amplified second operation output signal;

[0032] A fifth discrete filtering process is performed based on the grid frequency of the previous sampling period and the amplified second operation output signal to obtain the third operation output signal.

[0033] In a possible implementation manner of the first aspect, obtaining a current input voltage signal of a grid voltage in a current sampling period includes:

[0034] Acquire an initial input voltage signal of the grid voltage in a current sampling period;

[0035] Determine a coordinate transformation algorithm for performing coordinate transformation on the initial input voltage signal according to the type of the initial input voltage signal; wherein the type of the initial input voltage signal includes a three-phase grid voltage and a single-phase grid voltage;

[0036] The initial input voltage signal is subjected to coordinate transformation according to the coordinate transformation algorithm to obtain the input voltage signal corresponding to the initial input voltage signal.

[0037] In a second aspect, an embodiment of the present application provides a power grid voltage frequency detection system, the system comprising: a positive and negative sequence separation closed-loop control module and a signal operation module; wherein,

[0038] The grid voltage positive-negative sequence separation closed-loop control module is used to obtain the feedback voltage signal corresponding to the current input voltage signal of the grid voltage in the current sampling period and the previous input voltage signal in the previous sampling period, wherein the feedback voltage signal includes the previous positive-sequence fundamental component and the previous negative-sequence fundamental component; obtain the voltage signal to be separated in the current sampling period according to the current input voltage signal and the feedback voltage signal; perform positive-negative sequence voltage separation on the voltage signal to be separated to obtain the current positive-sequence fundamental component and the current negative-sequence fundamental component in the current sampling period;

[0039] The signal operation module is used to perform signal processing on the voltage signal to be separated and the current positive-sequence fundamental component of the current sampling period to obtain the grid frequency of the current sampling period in the grid voltage, and feed back the grid frequency of the current sampling period to the grid voltage positive and negative sequence separation closed-loop control module, so as to perform closed-loop feedback control of the next sampling period according to the grid frequency of the current sampling period, the current positive-sequence fundamental component, and the current negative-sequence fundamental component.

[0040] In a third aspect, an embodiment of the present application provides a power grid voltage frequency detection device, the device comprising a controller, and the controller executes a power grid voltage frequency detection method as described in any one of the above-mentioned first aspects.

[0041] In a fourth aspect, an embodiment of the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the grid voltage frequency detection method described in any one of the first aspects above is implemented.

[0042] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the grid voltage frequency detection method described in any one of the above-mentioned first aspects is implemented.

[0043] In a sixth aspect, an embodiment of the present application provides a computer program product. When the computer program product runs on a terminal device, the terminal device executes the power grid voltage and frequency detection method described in any one of the above-mentioned first aspects.

[0044] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0045] A grid voltage frequency detection method is provided through an embodiment of the present application. First, a feedback voltage signal corresponding to a current input voltage signal of the grid voltage in a current sampling period and a previous input voltage signal in a previous sampling period is obtained, wherein the feedback voltage signal includes a previous positive-sequence fundamental component and a previous negative-sequence fundamental component; a voltage signal to be separated in the current sampling period is obtained according to the current input voltage signal and the feedback voltage signal; then, positive-sequence and negative-sequence voltage separation is performed on the voltage signal to be separated to obtain a current positive-sequence fundamental component and a current negative-sequence fundamental component in the current sampling period; finally, signal processing is performed on the voltage signal to be separated and the current positive-sequence fundamental component in the current sampling period to obtain the grid frequency of the current sampling period in the grid voltage, so as to perform closed-loop feedback control of the next sampling period according to the grid frequency of the current sampling period, the current positive-sequence fundamental component, and the current negative-sequence fundamental component. By performing positive-sequence and negative-sequence voltage separation on the current input voltage signal of the current sampling period, and then using the obtained current positive-sequence fundamental component and current negative-sequence fundamental component for closed-loop feedback regulation in the next sampling period, real-time tracking of the grid frequency of the grid voltage is achieved, thereby improving the accuracy of grid frequency detection and the accuracy of frequency locking effect under conditions of grid imbalance. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0047] Figure 1 It is a flowchart of a method for detecting power grid voltage frequency provided by an embodiment of the present application;

[0048] Figure 2 This is a circuit structure diagram of a grid voltage frequency detection process provided by an embodiment of the present application;

[0049] Figure 3 It is a circuit structure diagram of a closed-loop control module for separating positive and negative sequence voltages of a power grid provided in one embodiment of the present application;

[0050] Figure 4 This is a circuit structure diagram of a grid voltage positive sequence extraction module provided in an embodiment of the present application;

[0051] Figure 5 This is a circuit structure diagram of a grid voltage negative sequence extraction module provided in an embodiment of the present application;

[0052] Figure 6 It is a circuit structure diagram of a parameter per unit module provided by an embodiment of the present application;

[0053] Figure 7 It is a structural schematic diagram of a power grid voltage frequency detection system provided by an embodiment of the present application;

[0054] Figure 8 It is a structural schematic diagram of a power grid voltage frequency detection device provided by an embodiment of the present application;

[0055] Fig. 9 It is a structural schematic diagram of an electronic device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0056] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0057] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0058] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0059] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0060] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0061] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0062] See also Figure 1 , Figure 1 It is a flow chart of a method for detecting power grid voltage frequency provided in one embodiment of the present application.

[0063] The method includes:

[0064] S11, obtaining a feedback voltage signal corresponding to a current input voltage signal of the grid voltage in a current sampling period and a previous input voltage signal in a previous sampling period, wherein the feedback voltage signal includes a previous positive sequence fundamental component and a previous negative sequence fundamental component;

[0065] S12, obtaining a voltage signal to be separated in a current sampling period according to the current input voltage signal and the feedback voltage signal;

[0066] S13, performing positive-sequence voltage separation on the voltage signal to be separated to obtain a current positive-sequence fundamental component and a current negative-sequence fundamental component of a current sampling period;

[0067] S14. Perform signal processing on the voltage signal to be separated and the current positive-sequence fundamental component of the current sampling period to obtain the grid frequency of the current sampling period in the grid voltage, so as to perform closed-loop feedback control of the next sampling period according to the grid frequency of the current sampling period, the current positive-sequence fundamental component, and the current negative-sequence fundamental component.

[0068] It should be noted that this method is mainly used in power grid systems, and can simultaneously meet the frequency detection requirements of single-phase grid voltage and three-phase grid voltage, and can accurately and quickly detect the frequency of grid voltage in both symmetrical and asymmetrical grid voltage situations. This method is mainly suitable for detection equipment such as inverters, rectifiers, and frequency converters that need to detect grid voltage frequency.

[0069] The current input voltage signal of the current sampling period is not a voltage signal directly obtained from the power grid, but a voltage signal obtained after coordinate transformation of the voltage signal directly obtained from the power grid. The voltage signal usually contains positive sequence components, negative sequence components, zero sequence components and various harmonic components. The feedback voltage signal is a voltage signal obtained after positive and negative sequence voltage separation from the previous input voltage signal obtained in the previous sampling period, that is, the previous positive sequence fundamental component and the previous negative sequence fundamental component. The previous positive sequence fundamental component and the previous negative sequence fundamental component are used as feedback signals to control the power grid frequency.

[0070] Positive and negative sequence voltage separation refers to the decomposition of the positive sequence component and negative sequence component in the voltage signal through a certain transformation form (such as symmetrical component method, Park transformation, etc.). In general, the positive sequence component refers to the voltage component whose rotation direction is the same as that of the power grid, representing the normal state of the power grid voltage; the negative sequence component refers to the voltage component whose rotation direction is opposite to that of the power grid, representing the unbalanced state of the power grid voltage.

[0071] The voltage signal to be separated is a voltage signal that is calculated based on the current input voltage signal and the feedback voltage signal in the current sampling period and needs to be further separated from the positive and negative sequence voltage. The current positive sequence fundamental component is the positive sequence component separated from the voltage signal to be separated by the positive and negative sequence voltage separation signal processing in the current sampling period; the current negative sequence fundamental component is the negative sequence component separated from the voltage signal to be separated by the positive and negative sequence voltage separation signal processing in the current sampling period. The grid frequency of the grid voltage is an important parameter for the stable operation of the grid system. The grid frequency of the current sampling period is the frequency of the alternating current in the grid obtained by signal processing the voltage signal to be separated and the current positive sequence fundamental component of the current sampling period, which is used for subsequent closed-loop feedback control. The grid frequency of the current sampling period, the current positive sequence fundamental component and the current negative sequence fundamental component are input into the grid voltage as feedback signals for use in the next sampling period.

[0072] It can be understood that, first, the feedback voltage signal corresponding to the current input voltage signal of the grid voltage in the current sampling period and the previous input voltage signal in the previous sampling period is obtained, wherein the feedback voltage signal includes the previous positive-sequence fundamental component and the previous negative-sequence fundamental component; according to the current input voltage signal and the feedback voltage signal, the voltage signal to be separated in the current sampling period is obtained; then, the positive-sequence and negative-sequence voltages of the voltage signal to be separated are separated to obtain the current positive-sequence fundamental component and the current negative-sequence fundamental component of the current sampling period; finally, the voltage signal to be separated and the current positive-sequence fundamental component of the current sampling period are signal processed to obtain the grid frequency of the current sampling period in the grid voltage, so as to perform closed-loop feedback control of the next sampling period according to the grid frequency of the current sampling period, the current positive-sequence fundamental component and the current negative-sequence fundamental component. By performing positive-sequence and negative-sequence voltage separation on the current input voltage signal of the current sampling period, and then using the obtained current positive-sequence fundamental component and current negative-sequence fundamental component for closed-loop feedback regulation in the next sampling period, real-time tracking of the grid frequency of the grid voltage is achieved, thereby improving the accuracy of grid voltage frequency detection and the accuracy of frequency locking effect under conditions of grid imbalance.

[0073] In a possible implementation, the current input voltage signal includes a current first input voltage signal and a current second input voltage signal, the previous positive-sequence fundamental component includes a previous first positive-sequence fundamental component and a previous second positive-sequence fundamental component, and the previous negative-sequence fundamental component includes a previous first negative-sequence fundamental component and a previous second negative-sequence fundamental component;

[0074] According to the current input voltage signal and the feedback voltage signal, the voltage signal to be separated in the current sampling period is obtained, including:

[0075] Perform difference calculation on the last first fundamental wave output signal obtained by adding the last first positive sequence fundamental wave component and the last first negative sequence fundamental wave component, and the current first input voltage signal to obtain the first voltage signal to be separated in the current sampling period;

[0076] The difference between the last second fundamental wave output signal obtained by adding the last second positive sequence fundamental wave component and the last second negative sequence fundamental wave component and the current second input voltage signal is calculated to obtain the second voltage signal to be separated in the current sampling period.

[0077] It should be noted that the current input voltage signal is a voltage signal obtained after coordinate transformation of the voltage signal directly obtained from the power grid. Usually, the voltage signal directly obtained from the power grid is transformed into two components of different phases in a two-phase rotating coordinate system through a coordinate transformation algorithm, namely, the current first input voltage signal and the current second input voltage signal. Correspondingly, the last positive sequence fundamental component includes the last first positive sequence fundamental component and the last second positive sequence fundamental component, and the last negative sequence fundamental component includes the last first negative sequence fundamental component and the last second negative sequence fundamental component. The last first positive sequence fundamental component and the last second positive sequence fundamental component are positive sequence components corresponding to two different phases in the last sampling period, and are used as feedback voltage signals for closed-loop feedback control of the current sampling period; the last first negative sequence fundamental component and the last second negative sequence fundamental component are negative sequence components corresponding to two different phases in the last sampling period, and are used as feedback voltage signals for closed-loop feedback control of the current sampling period.

[0078] Correspondingly, the voltage signal to be separated includes a first voltage signal to be separated and a second voltage signal to be separated. The first voltage signal to be separated is a voltage signal that is calculated according to the current first input voltage signal and the feedback voltage signal in the current sampling cycle and needs to be further separated from the positive and negative sequence voltages. The second voltage signal to be separated is a voltage signal that is calculated according to the current second input voltage signal and the feedback voltage signal in the current sampling cycle and needs to be further separated from the positive and negative sequence voltages.

[0079] Specifically, the previous first positive sequence fundamental component and the previous first negative sequence fundamental component are added to obtain the previous first fundamental output signal, which is the fundamental voltage output signal of the first phase in the previous sampling period, and represents the part contributed by the positive sequence fundamental component and the negative sequence fundamental component in the previous first input voltage signal. The previous first fundamental output signal and the current first input voltage signal are subjected to difference calculation to obtain the first voltage signal to be separated; the first voltage signal to be separated reflects the change amount of the first phase voltage in the current sampling period, that is, other components in the current first input voltage signal except the positive sequence fundamental component and the negative sequence fundamental component, including harmonics, noise, etc., that is, reflects the deviation information between the current first input voltage signal and its fundamental component.

[0080] The previous second positive-sequence fundamental component and the previous second negative-sequence fundamental component are added to obtain the previous second fundamental output signal, which represents the fundamental voltage output signal of the second phase in the previous sampling period, and represents the part contributed by the positive-sequence fundamental component and the negative-sequence fundamental component in the previous second input voltage signal. The previous second fundamental output signal and the current second input voltage signal are subjected to difference calculation to obtain the second voltage signal to be separated; the second voltage signal to be separated reflects the change amount of the second phase voltage in the current sampling period, that is, other components in the current second input voltage signal except the positive-sequence fundamental component and the negative-sequence fundamental component, including harmonics, noise, etc., that is, reflects the deviation information between the current second input voltage signal and its fundamental component.

[0081] That is, the calculation formula of the first voltage signal to be separated is as follows:

[0082] v α =v′ α_P +v′ α_N -u α ;

[0083] The calculation formula of the second voltage signal to be separated is as follows:

[0084] v β =v′ β_P +v′ β_N -u β ;

[0085] Among them, v α Represents the first voltage signal to be separated, v β Indicates the second voltage signal to be separated, u α Indicates the current first input voltage signal, u β Represents the current second input voltage signal, v′ α_P Represents the previous first positive sequence fundamental component, v′ β_P Represents the second positive sequence fundamental component, v′ α_N Represents the previous first negative sequence fundamental component, v′ β_N Represents the previous second negative sequence fundamental component.

[0086] As shown in 2, Figure 2 It is a circuit structure diagram of a grid voltage frequency detection process provided by an embodiment of the present application. Figure 2 Middle,U a , U b , U c Indicates the three-phase input voltage signal; U ab , U bc , U ca Represents single-phase input voltage signal; v α represents the first voltage signal to be separated; vβ_P Indicates the current second positive sequence fundamental component; F x Indicates per unit value; K1 indicates the preset multiple; F0 indicates the preset feedforward angular frequency; ω c Indicates the grid frequency of the current sampling period. By separating the positive and negative sequence voltages of the input voltage signal, the positive sequence fundamental component is obtained, and then the separated voltage signal and the positive sequence fundamental component are processed to obtain the grid frequency of the current sampling period. The grid frequency of the current sampling period is input into the grid voltage positive and negative sequence separation closed-loop control module for closed-loop feedback control to adjust the system's operating parameters and ensure that the system can adapt to changes in the grid frequency. The signal processing here can include multiplication, amplification, normalization, and discrete filtering.

[0087] In a possible implementation, the voltage signal to be separated is subjected to positive and negative sequence voltage separation to obtain a current positive sequence fundamental component and a current negative sequence fundamental component of a current sampling period, including:

[0088] Extracting positive-sequence components from the first voltage signal to be separated and the second voltage signal to be separated to obtain a current first positive-sequence fundamental component and a current second positive-sequence fundamental component;

[0089] Negative-sequence components are extracted from the first voltage signal to be separated and the second voltage signal to be separated to obtain a current first negative-sequence fundamental component and a current second negative-sequence fundamental component.

[0090] Specifically, Figure 3 As shown, Figure 3 It is a circuit structure diagram of a grid voltage positive and negative sequence voltage separation closed-loop control module provided in one embodiment of the present application. Figure 3 In the grid voltage positive sequence extraction module, the module is used to extract the positive sequence fundamental component from the voltage signal to be separated. The positive sequence fundamental component is the main part of the grid voltage and is crucial to the stability of the grid. The grid voltage negative sequence extraction module is used to extract the negative sequence fundamental component from the voltage signal to be separated. The negative sequence fundamental component is usually caused by grid faults, unbalanced loads or other asymmetric factors, which will have an adverse effect on the stability of the grid. Figure 3 As shown, U a , U b , U c Indicates the three-phase input voltage signal; U ab , U bc , U ca Represents single-phase input voltage signal; u α Indicates the current first input voltage signal; u β Represents the current second input voltage signal; v α represents the first voltage signal to be separated; v βrepresents the second voltage signal to be separated; v α_P Represents the current first positive sequence fundamental component; v β_P Indicates the current second positive sequence fundamental component; v α_N Indicates the current first negative sequence fundamental component; v β_N Represents the current second negative-sequence fundamental component. Positive-sequence component extraction is to extract the positive-sequence fundamental component from the voltage signal through the grid voltage positive-sequence extraction module. Negative-sequence component extraction is to extract the negative-sequence fundamental component from the voltage signal through the grid voltage negative-sequence extraction module. The current first positive-sequence fundamental component and the current second positive-sequence fundamental component are positive-sequence fundamental components extracted from the first signal to be separated and the second signal to be separated in the current sampling period; the current first positive-sequence fundamental component and the current second positive-sequence fundamental component represent the normal state of the grid voltage. The current first negative-sequence fundamental component and the current second negative-sequence fundamental component are negative-sequence fundamental components extracted from the first signal to be separated and the second signal to be separated in the current sampling period; the current first negative-sequence fundamental component and the current second negative-sequence fundamental component represent the unbalanced state of the grid voltage.

[0091] It can be understood that the positive-sequence fundamental component and the negative-sequence fundamental component play an important role in evaluating the state of the grid voltage and detecting imbalance. By using these components to calculate the grid frequency, etc., the stability and reliability of the grid voltage can be ensured, and the occurrence of voltage fluctuations and imbalance can be reduced.

[0092] In a possible implementation, extracting positive-sequence components from the first voltage signal to be separated and the second voltage signal to be separated to obtain a current first positive-sequence fundamental component and a second positive-sequence fundamental component includes:

[0093] Performing a first discrete filtering process based on the difference between the first voltage signal to be separated and the second voltage signal to be separated and the power grid frequency of the previous sampling period to obtain a current first positive sequence fundamental component;

[0094] A second discrete filtering process is performed based on the sum of the first voltage signal to be separated and the second voltage signal to be separated, and the power grid frequency of the previous sampling period to obtain a current second positive-sequence fundamental component.

[0095] It should be noted that if Figure 4 As shown, Figure 4 It is a circuit structure diagram of a grid voltage positive sequence extraction module provided in one embodiment of the present application. Figure 4 In, v α Represents the first voltage signal to be separated, v β represents the second voltage signal to be separated; v α_P is the current first positive sequence fundamental component, v β_P is the current second positive sequence fundamental component, ω′ cis the grid frequency of the previous sampling cycle. The grid voltage positive sequence extraction module includes a first discrete filter and a second discrete filter, and the first discrete filter and the second discrete filter are used to discretely process the first voltage signal to be separated, the second voltage signal to be separated, and the grid frequency of the previous sampling cycle to obtain the current first positive sequence fundamental component and the current second positive sequence fundamental component. The first discrete filter and the second discrete filter are designed according to the preset signal processing requirements, and are used to remove noise, smooth signals, or extract specific frequency components.

[0096] Specifically, the first discrete filtering process can be expressed as:

[0097]

[0098] The second discrete filtering process can be expressed as:

[0099]

[0100] Among them, v α_P is the current first positive sequence fundamental component, v β_P is the current second positive sequence fundamental component, v α is the first voltage signal to be separated, v β is the second voltage signal to be separated, T s is the sampling period of the grid voltage, ω′ c is the grid frequency of the previous sampling period, k is the amplification factor, and z is the discretization operator.

[0101] It should be noted that the sampling period of the grid voltage is T s is the time interval for sampling the grid voltage. c is the grid frequency of the previous sampling period, ω′ c is a variable. The value of the amplification factor k is generally set between 50 and 100, and there is no limit on this. The discretization operator usually refers to the algorithm used in the process of converting a continuous-time signal into a discrete-time signal, which is used to convert a continuous grid voltage signal into a discrete sampling value sequence for subsequent signal processing and analysis.

[0102] It can be understood that in this embodiment, the first discrete filter and the second discrete filter are used to remove high-frequency noise and harmonic components in the first voltage signal to be separated and the second voltage signal to be separated, and separate the positive-sequence fundamental component related to the grid frequency; at the same time, the grid frequency is fed back to the first discrete filter and the second discrete filter, and the parameters of the first discrete filter and the second discrete filter are dynamically adjusted according to the changes in the grid frequency to ensure that the positive-sequence fundamental component can be accurately extracted.

[0103] In a possible implementation, performing negative-sequence component extraction on the first voltage signal to be separated and the second voltage signal to be separated to obtain a current first negative-sequence fundamental component and a current second negative-sequence fundamental component includes:

[0104] Performing a third discrete filtering process based on the difference between the first voltage signal to be separated, the second voltage signal to be separated, and the power grid frequency of the previous sampling period to obtain a current first negative-sequence fundamental component;

[0105] A fourth discrete filtering process is performed based on the sum of the first voltage signal to be separated and the second voltage signal to be separated, and the power grid frequency of the previous sampling period to obtain a current second negative-sequence fundamental component.

[0106] It should be noted that if Figure 5 As shown, Figure 5 It is a circuit structure diagram of a grid voltage negative sequence extraction module provided in one embodiment of the present application. Figure 5 In, v α Represents the first voltage signal to be separated, v β represents the second voltage signal to be separated; v α_N is the current first negative sequence fundamental component, v β_N is the current second negative sequence fundamental component, ω′ c is the grid frequency of the previous sampling cycle. The grid voltage negative sequence extraction module includes a third discrete filter and a fourth discrete filter, and the first voltage signal to be separated, the second voltage signal to be separated and the grid frequency of the previous sampling cycle are discretely processed by the third discrete filter and the fourth discrete filter to obtain the current first negative sequence fundamental component and the current second negative sequence fundamental component. The third discrete filter and the fourth discrete filter are designed according to the preset signal processing requirements, and are used to remove noise, smooth signals or extract specific frequency components.

[0107] The third discrete filtering process can be expressed as:

[0108]

[0109] The fourth discrete filtering process can be expressed as:

[0110]

[0111] Among them, v α_N is the current first negative sequence fundamental component, v β_N is the current second negative sequence fundamental component, v α is the first voltage signal to be separated, v β is the second voltage signal to be separated, T s is the sampling period of the grid voltage, ω′ cis the grid frequency of the previous sampling period, k is the amplification factor, and z is the discretization operator.

[0112] It can be understood that in this embodiment, the third discrete filter and the fourth discrete filter are used to remove high-frequency noise and harmonic components in the first voltage signal to be separated and the second voltage signal to be separated, and separate the negative-sequence fundamental component related to the grid frequency; at the same time, the grid frequency is fed back to the third discrete filter and the fourth discrete filter, and the parameters of the third discrete filter and the fourth discrete filter are dynamically adjusted according to the change of the grid frequency to ensure that the negative-sequence fundamental component can be accurately extracted.

[0113] In a possible implementation, signal processing is performed on the voltage signal to be separated and the current positive sequence fundamental component of the current sampling period to obtain the grid frequency of the current sampling period in the grid voltage, including:

[0114] Performing a first multiplication operation on the first voltage signal to be separated and the current second positive sequence fundamental wave component to obtain a first operation output signal;

[0115] Perform a second multiplication operation on the per-unit value of the current sampling period and the first operation output signal to obtain a second operation output signal; the per-unit value is determined based on the current first positive sequence fundamental component and the current second positive sequence fundamental component;

[0116] Perform a fifth discrete filtering process based on the second operation output signal to obtain a third operation output signal;

[0117] Based on the third operation output signal and the preset feedforward angular frequency, the grid frequency of the current sampling period in the grid voltage is obtained.

[0118] Specifically, Figure 2As shown in, first, by performing a first multiplication operation on the first voltage signal to be separated and the current second positive sequence fundamental component, the part related to the current second positive sequence fundamental component in the first voltage signal to be separated is adjusted or enhanced, thereby obtaining a first operation output signal. Secondly, the per-unit value obtained by converting the current first positive sequence fundamental component and the current second positive sequence fundamental component is subjected to a second multiplication operation with the first operation output signal to obtain a second operation output signal; that is, the second operation output signal is an output signal obtained by adjusting or enhancing the first operation output signal by the per-unit value to reflect the relative importance of the current first positive sequence fundamental component and the current second positive sequence fundamental component. Then, the second operation output signal is input into the fifth discrete filter for fifth discrete filtering to obtain a third operation output signal. The fifth discrete filter is designed according to the preset signal processing requirements and is used to remove noise, smooth signals or extract specific frequency components. Finally, the third operation output signal is subjected to a sum operation with the preset feedforward angular frequency to obtain the grid frequency of the current sampling period in the grid voltage. That is, the third operation output signal obtained after filtering is associated with the preset feedforward angular frequency to obtain the grid frequency of the current sampling period. The grid frequency of the current sampling period is input again into the grid voltage positive sequence extraction module and the grid voltage negative sequence extraction module to adjust the positive sequence fundamental component and the negative sequence fundamental component of the next sampling period to realize closed-loop feedback control of the grid frequency.

[0119] It should be noted that Figure 2 The parameter per unit module is a module that converts the current first positive sequence fundamental component and the current second positive sequence fundamental component to obtain a per unit value. x It is a unitless quantity used to represent the proportional relationship between the actual value and the reference value. The per-unit value helps to eliminate the influence of different dimensions on subsequent calculations. The preset feedforward angular frequency F0 is an angular velocity proportional to the grid voltage frequency and is a pre-set value. By performing an AND operation on the preset feedforward angular frequency and the third operation output signal, further adjustment of the grid frequency can be achieved.

[0120] In a possible implementation, the step of determining the per-unit value of the current sampling period includes:

[0121] Based on the square of the current first positive sequence fundamental wave component, the square of the current second positive sequence fundamental wave component and the preset per unit parameter, the per unit value of the current sampling period is obtained.

[0122] Specifically, Figure 6 As shown, Figure 61 is a circuit structure diagram of a parameter per unit module provided in an embodiment of the present application. The specific process of the parameter per unit module calculating the per unit value is: adding the square of the current first positive sequence fundamental wave component and the square of the current second positive sequence fundamental wave component to obtain the added value; then, dividing the preset per unit parameter by the added value to obtain the per unit value. Figure 6 Medium, F x Indicates per unit value, v α_P Represents the current first positive sequence fundamental component; v β_P represents the current second positive sequence fundamental component; the preset per-unit parameter is a preset constant. In this embodiment, the value of the preset per-unit parameter can be 300, and no specific limitation is made to this.

[0123] In a possible implementation, performing a fifth discrete filtering process based on the second operation output signal to obtain a third operation output signal includes:

[0124] Amplifying the second operation output signal based on a preset multiple to obtain an amplified second operation output signal;

[0125] A fifth discrete filtering process is performed based on the grid frequency of the previous sampling period and the amplified second operation output signal to obtain a third operation output signal.

[0126] Specifically, Figure 2 As shown, the grid frequency of the previous sampling period is obtained after the positive and negative sequence voltages are separated in the previous sampling period. The fifth discrete filter is a filter designed according to a preset fifth discrete filter expression. First, the second operation output signal is amplified by a preset multiple to obtain an amplified second operation output signal, and the amplitude of the second operation output signal is increased by amplifying the signal so that it is easier to detect and identify in the subsequent filtering process. Then, the amplified second operation output signal and the grid frequency of the previous sampling period are subjected to the fifth discrete filtering process by the fifth discrete filter to obtain a third operation output signal.

[0127] Specifically, the fifth discrete filtering process can be expressed as:

[0128]

[0129] Among them, Y LPF is the third operation output signal, T s is the sampling period of the grid voltage, ω′ c is the grid frequency of the previous sampling period, X is the amplified second operation output signal, k is the amplification factor, and z is the discretization operator.

[0130] The amplified second operation output signal X can be expressed as:

[0131] X=K1×v α ×v β_P ×F x ;

[0132] Among them, K1 is the preset multiple, v α is the first voltage signal to be separated, v β_P is the current second positive sequence fundamental component, F x Is the per unit value.

[0133] It should be noted that the preset multiple K1 is a pre-set value for signal amplification. Generally, the value of the preset multiple is a negative number, such as -100. In this embodiment, the value of the preset multiple is not specifically limited.

[0134] In a possible implementation, obtaining a current input voltage signal of a grid voltage in a current sampling period includes:

[0135] Obtaining the initial input voltage signal of the grid voltage in the current sampling period;

[0136] According to the type of the initial input voltage signal, a coordinate transformation algorithm for performing coordinate transformation on the initial input voltage signal is determined; wherein the type of the initial input voltage signal includes a three-phase grid voltage and a single-phase grid voltage;

[0137] The initial input voltage signal is subjected to coordinate transformation according to a coordinate transformation algorithm to obtain a current input voltage signal corresponding to the initial input voltage signal.

[0138] It should be noted that in the power grid system, the grid voltage can be divided into single-phase grid voltage and three-phase grid voltage. In order to simplify the analysis and control of voltage signal processing, the three-phase grid voltage or single-phase grid voltage is usually converted into a voltage signal of a two-phase rotating coordinate system during the process of detecting the grid voltage frequency.

[0139] The initial input voltage signal is a voltage signal directly obtained from the power grid. In the process of detecting the frequency of the power grid voltage through detection equipment such as a frequency converter, it is necessary to judge the type of the initial input voltage signal directly obtained. If the initial input voltage signal is a three-phase power grid voltage, the coordinate transformation algorithm corresponding to the three-phase power grid voltage (such as the Clark coordinate transformation algorithm) is selected to perform coordinate transformation on the initial input voltage signal to obtain the current input voltage signal. If the initial input voltage signal is a single-phase power grid voltage, the coordinate transformation algorithm corresponding to the single-phase power grid voltage (SOGI coordinate transformation algorithm) is selected to perform coordinate transformation on the initial input voltage signal to obtain the current input voltage signal.

[0140] like Figure 3 As shown, Figure 31 is a schematic diagram of a circuit structure of a closed-loop control module for separating positive and negative sequence voltages of a power grid provided in an embodiment of the present application. Figure 3 In the process, different coordinate transformation algorithms are selected to process the input initial input voltage signal according to whether single-phase grid voltage frequency detection or three-phase grid voltage frequency detection is selected in the three-phase / single-phase frequency locking selection module. If three-phase grid voltage transformation is selected, the three-phase grid voltage transformation module executes the three-phase coordinate transformation algorithm on the initial input voltage signal; if single-phase grid voltage transformation is selected, the single-phase grid voltage transformation module executes the single-phase coordinate transformation algorithm on the initial input voltage signal. Both algorithms transform the initial input voltage signal into a quantity in a two-phase rotating coordinate system through a coordinate transformation algorithm, and the output result is the current input voltage signal, that is, the current first input voltage signal u α and the current second input voltage signal u β By converting and simplifying the complex input voltage signal, the subsequent processing and control of the voltage signal becomes easier.

[0141] It can be understood that the grid voltage frequency detection method provided in the embodiment of the present application has the following advantages compared with the existing detection methods: 1) no special hardware circuit is required, thereby reducing the complexity of the design and saving costs; 2) it can be compatible with single-phase and three-phase grid voltage frequency detection at the same time, and has a wide range of adaptability; 3) it can track the changes in grid voltage frequency in real time, with short response time and high detection accuracy; 4) the discrete control method can be well deployed in a microprocessor-based system in a program manner.

[0142] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0143] Corresponding to a grid voltage frequency detection method in the above embodiment, Figure 7 A schematic structural diagram of a power grid voltage and frequency detection system provided in an embodiment of the present application is shown. For ease of explanation, only the parts related to the embodiment of the present application are shown.

[0144] Reference Figure 7 , the power grid voltage and frequency detection system 20 of this embodiment includes:

[0145] Positive and negative sequence separation closed-loop control module 21 and signal operation module 22; wherein,

[0146] The grid voltage positive-negative sequence separation closed-loop control module 21 is used to obtain the feedback voltage signal corresponding to the current input voltage signal of the grid voltage in the current sampling period and the previous input voltage signal in the previous sampling period, wherein the feedback voltage signal includes the previous positive-sequence fundamental component and the previous negative-sequence fundamental component; obtain the voltage signal to be separated in the current sampling period according to the current input voltage signal and the feedback voltage signal; perform positive-negative sequence voltage separation on the voltage signal to be separated to obtain the current positive-sequence fundamental component and the current negative-sequence fundamental component of the current sampling period;

[0147] The signal operation module 22 is used to perform signal processing on the voltage signal to be separated and the current positive-sequence fundamental component of the current sampling period to obtain the grid frequency of the current sampling period in the grid voltage, and feed back the grid frequency of the current sampling period to the grid voltage positive and negative sequence separation closed-loop control module 21, so as to perform closed-loop feedback control of the next sampling period according to the grid frequency of the current sampling period, the current positive-sequence fundamental component, and the current negative-sequence fundamental component.

[0148] It can be understood that in the embodiment of the present application, the grid voltage positive and negative sequence separation closed-loop control module 21 obtains the feedback voltage signal corresponding to the current input voltage signal of the grid voltage in the current sampling period and the previous input voltage signal of the previous sampling period, wherein the feedback voltage signal includes the previous positive sequence fundamental component and the previous negative sequence fundamental component; according to the current input voltage signal and the feedback voltage signal, the voltage signal to be separated in the current sampling period is obtained; and the voltage signal to be separated is subjected to positive and negative sequence voltage separation to obtain the current positive sequence fundamental component and the current negative sequence fundamental component of the current sampling period. Then, the signal operation module 22 performs signal processing on the voltage signal to be separated in the current sampling period and the current positive sequence fundamental component to obtain the grid frequency of the current sampling period in the grid voltage, so as to perform closed-loop feedback control of the next sampling period according to the grid frequency of the current sampling period, the current positive sequence fundamental component, and the current negative sequence fundamental component. By performing positive-sequence and negative-sequence voltage separation on the current input voltage signal of the current sampling period, and then using the obtained current positive-sequence fundamental component and current negative-sequence fundamental component for closed-loop feedback regulation in the next sampling period, real-time tracking of the grid frequency of the grid voltage is achieved, thereby improving the accuracy of grid voltage frequency detection and the accuracy of frequency locking effect under conditions of grid imbalance.

[0149] Furthermore, the grid voltage positive and negative sequence separation closed-loop control module 21 includes:

[0150] A first voltage signal to be separated determination submodule, used for performing difference calculation between a previous first fundamental wave output signal obtained by adding a previous first positive sequence fundamental wave component and a previous first negative sequence fundamental wave component and a current first input voltage signal, to obtain a first voltage signal to be separated in a current sampling period;

[0151] A second voltage signal to be separated determination submodule, used for performing difference calculation between a previous second fundamental wave output signal obtained by adding a previous second positive sequence fundamental wave component and a previous second negative sequence fundamental wave component and a current second input voltage signal, to obtain a second voltage signal to be separated in a current sampling period;

[0152] Among them, the current input voltage signal includes the current first input voltage signal and the current second input voltage signal, the previous positive-sequence fundamental component includes the previous first positive-sequence fundamental component and the previous second positive-sequence fundamental component, and the previous negative-sequence fundamental component includes the previous first negative-sequence fundamental component and the previous second negative-sequence fundamental component.

[0153] Furthermore, the grid voltage positive and negative sequence separation closed-loop control module 21 includes:

[0154] A grid voltage positive sequence extraction module, used for extracting positive sequence components from the first voltage signal to be separated and the second voltage signal to be separated, to obtain a current first positive sequence fundamental component and a current second positive sequence fundamental component;

[0155] The grid voltage negative sequence extraction module is used to extract negative sequence components from the first voltage signal to be separated and the second voltage signal to be separated to obtain the current first negative sequence fundamental component and the current second negative sequence fundamental component.

[0156] Furthermore, the grid voltage positive and negative sequence separation closed-loop control module 21 includes:

[0157] A first positive-sequence fundamental component determination submodule, configured to perform a first discrete filtering process based on a difference between the first voltage signal to be separated and the second voltage signal to be separated, and a power grid frequency in a previous sampling period, to obtain a current first positive-sequence fundamental component;

[0158] The second positive-sequence fundamental component determination submodule is used to perform a second discrete filtering process based on the sum of the first voltage signal to be separated and the second voltage signal to be separated and the grid frequency of the previous sampling period to obtain a current second positive-sequence fundamental component.

[0159] Furthermore, the grid voltage positive and negative sequence separation closed-loop control module 21 includes:

[0160] A first negative-sequence fundamental component determination submodule, configured to perform a third discrete filtering process based on a difference between the first voltage signal to be separated, the second voltage signal to be separated, and the grid frequency of the previous sampling period to obtain a current first negative-sequence fundamental component;

[0161] The second negative-sequence fundamental component determination submodule is used to perform a fourth discrete filtering process based on the sum of the first voltage signal to be separated and the second voltage signal to be separated and the grid frequency of the previous sampling period to obtain the current second negative-sequence fundamental component.

[0162] Furthermore, the signal operation module 22 includes:

[0163] A first signal operation submodule, used for performing a first multiplication operation on the first voltage signal to be separated and the current second positive sequence fundamental component to obtain a first operation output signal;

[0164] The second signal operation submodule is used to perform a second multiplication operation on the per-unit value of the current sampling period and the first operation output signal to obtain a second operation output signal; the per-unit value is determined based on the current first positive sequence fundamental component and the current second positive sequence fundamental component;

[0165] A third signal operation submodule, configured to perform a fifth discrete filtering process based on the second operation output signal to obtain a third operation output signal;

[0166] The fourth signal operation submodule is used to obtain the grid frequency of the current sampling period in the grid voltage based on the third operation output signal and the preset feedforward angular frequency.

[0167] Furthermore, the signal operation module 22 includes:

[0168] The parameter per unit module is used to calculate based on the square of the current first positive sequence fundamental component, the square of the current second positive sequence fundamental component and the preset per unit parameter to obtain the per unit value of the current sampling period.

[0169] Furthermore, the third signal operation submodule is specifically used for:

[0170] Amplifying the second operation output signal based on a preset multiple to obtain an amplified second operation output signal;

[0171] A fifth discrete filtering process is performed based on the grid frequency of the previous sampling period and the amplified second operation output signal to obtain a third operation output signal.

[0172] Furthermore, the grid voltage positive and negative sequence separation closed-loop control module 21 includes a three-phase / single-phase frequency locking selection module, which is specifically used for:

[0173] Obtaining the initial input voltage signal of the grid voltage in the current sampling period;

[0174] According to the type of the initial input voltage signal, a coordinate transformation algorithm for performing coordinate transformation on the initial input voltage signal is determined; wherein the type of the initial input voltage signal includes a three-phase grid voltage and a single-phase grid voltage;

[0175] The initial input voltage signal is subjected to coordinate transformation according to a coordinate transformation algorithm to obtain a current input voltage signal corresponding to the initial input voltage signal.

[0176] It should be noted that the information interaction, execution process and other contents between the modules in the above-mentioned power grid voltage and frequency detection system 20 are based on the same concept as the method embodiment of the present application. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0177] The present application also provides a power grid voltage frequency detection device, such as Figure 8 As shown, Figure 8 This is a schematic diagram of the structure of a power grid voltage frequency detection device provided in one embodiment of the present application. Figure 8 The grid voltage and frequency detection device 30 includes a controller 31, and the controller 31 executes any of the grid voltage and frequency detection methods described above.

[0178] The present application also provides an electronic device, such as Fig. 9 As shown, Fig. 9 This is a schematic diagram of the structure of an electronic device provided by an embodiment of the present application. Fig. 9 The electronic device 40 of this embodiment includes: a memory 41, a processor 42, and a computer program stored in the memory 41 and executable on the processor 42. When the processor 42 executes the computer program, the steps in any one of the above-mentioned embodiments of the grid voltage and frequency detection method are implemented.

[0179] The embodiment of the present application further provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments can be implemented.

[0180] An embodiment of the present application provides a computer program product. When the computer program product runs on a mobile terminal, the mobile terminal can implement the steps in the above-mentioned method embodiments when executing the computer program product.

[0181] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, which can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of the above-mentioned method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may at least include: any entity or device that can carry the computer program code to the camera / terminal device, a recording medium, a computer memory, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), an electric carrier signal, a telecommunication signal, and a software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk or an optical disk. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electric carrier signals and telecommunication signals.

[0182] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0183] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0184] In the embodiments provided in the present application, it should be understood that the disclosed devices / network equipment and methods can be implemented in other ways. For example, the device / network equipment embodiments described above are only schematic. For example, the division of modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0185] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0186] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for detecting power grid voltage frequency, characterized in that: include: Acquire a feedback voltage signal corresponding to a current input voltage signal of the grid voltage in a current sampling period and a previous input voltage signal in a previous sampling period, wherein the feedback voltage signal includes a previous positive sequence fundamental component and a previous negative sequence fundamental component; Obtaining the voltage signal to be separated in the current sampling period according to the current input voltage signal and the feedback voltage signal; Performing positive-sequence and negative-sequence voltage separation on the voltage signal to be separated to obtain a current positive-sequence fundamental component and a current negative-sequence fundamental component of the current sampling period; Signal processing is performed on the voltage signal to be separated and the current positive-sequence fundamental component of the current sampling period to obtain the grid frequency of the current sampling period in the grid voltage, so as to perform closed-loop feedback control of the next sampling period according to the grid frequency of the current sampling period, the current positive-sequence fundamental component, and the current negative-sequence fundamental component.

2. The method for detecting the voltage frequency of a power grid according to claim 1, characterized in that: The current input voltage signal includes a current first input voltage signal and a current second input voltage signal, the previous positive-sequence fundamental component includes a previous first positive-sequence fundamental component and a previous second positive-sequence fundamental component, and the previous negative-sequence fundamental component includes a previous first negative-sequence fundamental component and a previous second negative-sequence fundamental component; The step of obtaining the voltage signal to be separated in the current sampling period according to the current input voltage signal and the feedback voltage signal includes: Performing difference calculation on a previous first fundamental wave output signal obtained by adding the previous first positive-sequence fundamental wave component and the previous first negative-sequence fundamental wave component and the current first input voltage signal to obtain a first voltage signal to be separated in the current sampling period; The difference between the last second fundamental wave output signal obtained by adding the last second positive-sequence fundamental wave component and the last second negative-sequence fundamental wave component and the current second input voltage signal is calculated to obtain the second voltage signal to be separated in the current sampling period.

3. The method for detecting the voltage frequency of a power grid according to claim 2, characterized in that: The step of performing positive-sequence and negative-sequence voltage separation on the voltage signal to be separated to obtain a current positive-sequence fundamental component and a current negative-sequence fundamental component of the current sampling period includes: Extracting positive-sequence components from the first voltage signal to be separated and the second voltage signal to be separated to obtain a current first positive-sequence fundamental component and a current second positive-sequence fundamental component; Negative-sequence components are extracted from the first voltage signal to be separated and the second voltage signal to be separated to obtain a current first negative-sequence fundamental component and a current second negative-sequence fundamental component.

4. The method for detecting the voltage frequency of a power grid according to claim 3, characterized in that: The extracting positive-sequence components of the first voltage signal to be separated and the second voltage signal to be separated to obtain the current first positive-sequence fundamental component and the second positive-sequence fundamental component includes: Performing a first discrete filtering process based on the difference between the first voltage signal to be separated and the second voltage signal to be separated, and the grid frequency of the last sampling period, to obtain the current first positive-sequence fundamental component; A second discrete filtering process is performed based on the sum of the first voltage signal to be separated and the second voltage signal to be separated, and the grid frequency of the previous sampling period to obtain the current second positive-sequence fundamental component.

5. The method for detecting the voltage frequency of a power grid according to claim 4, characterized in that: The extracting negative-sequence components of the first voltage signal to be separated and the second voltage signal to be separated to obtain a current first negative-sequence fundamental component and a current second negative-sequence fundamental component includes: Performing a third discrete filtering process based on the difference between the first voltage signal to be separated, the second voltage signal to be separated, and the grid frequency of the previous sampling period to obtain the current first negative-sequence fundamental component; A fourth discrete filtering process is performed based on the sum of the first voltage signal to be separated and the second voltage signal to be separated, and the grid frequency of the previous sampling period to obtain the current second negative-sequence fundamental component.

6. The method for detecting the voltage frequency of a power grid according to claim 3, characterized in that: The performing signal processing on the voltage signal to be separated and the current positive sequence fundamental component of the current sampling period to obtain the grid frequency of the current sampling period in the grid voltage includes: Performing a first multiplication operation on the first voltage signal to be separated and the current second positive-sequence fundamental component to obtain a first operation output signal; Performing a second multiplication operation on the per-unit value of the current sampling period and the first operation output signal to obtain a second operation output signal; the per-unit value is determined based on the current first positive-sequence fundamental component and the current second positive-sequence fundamental component; Performing a fifth discrete filtering process based on the second operation output signal to obtain a third operation output signal; Based on the third operation output signal and the preset feedforward angular frequency, the grid frequency of the current sampling period in the grid voltage is obtained.

7. The method for detecting the voltage frequency of a power grid according to claim 6, characterized in that: The performing a fifth discrete filtering process based on the second operation output signal to obtain a third operation output signal comprises: Amplifying the second operation output signal based on a preset multiple to obtain an amplified second operation output signal; A fifth discrete filtering process is performed based on the grid frequency of the previous sampling period and the amplified second operation output signal to obtain the third operation output signal.

8. The method for detecting the voltage frequency of a power grid according to claim 1, characterized in that: The step of obtaining a current input voltage signal of the grid voltage in a current sampling period includes: Acquire an initial input voltage signal of the grid voltage in a current sampling period; Determine a coordinate transformation algorithm for performing coordinate transformation on the initial input voltage signal according to the type of the initial input voltage signal; wherein the type of the initial input voltage signal includes a three-phase grid voltage and a single-phase grid voltage; The initial input voltage signal is subjected to coordinate transformation according to the coordinate transformation algorithm to obtain the current input voltage signal corresponding to the initial input voltage signal.

9. A power grid voltage frequency detection system, characterized in that: include: Positive and negative sequence separation closed-loop control module and signal operation module; among which, The grid voltage positive-negative sequence separation closed-loop control module is used to obtain the feedback voltage signal corresponding to the current input voltage signal of the grid voltage in the current sampling period and the previous input voltage signal in the previous sampling period, wherein the feedback voltage signal includes the previous positive-sequence fundamental component and the previous negative-sequence fundamental component; obtain the voltage signal to be separated in the current sampling period according to the current input voltage signal and the feedback voltage signal; perform positive-negative sequence voltage separation on the voltage signal to be separated to obtain the current positive-sequence fundamental component and the current negative-sequence fundamental component in the current sampling period; The signal operation module is used to perform signal processing on the voltage signal to be separated and the current positive-sequence fundamental component of the current sampling period to obtain the grid frequency of the current sampling period in the grid voltage, and feed back the grid frequency of the current sampling period to the grid voltage positive and negative sequence separation closed-loop control module, so as to perform closed-loop feedback control of the next sampling period according to the grid frequency of the current sampling period, the current positive-sequence fundamental component, and the current negative-sequence fundamental component.

10. A power grid voltage frequency detection device, characterized in that: It comprises a controller, wherein the controller executes the grid voltage frequency detection method according to any one of claims 1 to 8.

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