Micro-grid frequency detection method, system, equipment and medium

Abstract

The invention belongs to the technical field of power grid detection, and discloses a micro-grid frequency detection method, system, equipment and medium, and the method comprises the following steps: collecting a voltage signal of a micro-grid system, and distinguishing and marking according to the voltage type of a three-phase power grid; based on the collected voltage signals, the amplitude and phase of each phase voltage signal are extracted, a three-phase power grid voltage phasor expression is constructed, and difference frequency phase components are extracted through time domain analysis and coordinate transformation; calculating the increment of the future difference frequency phase component based on the difference frequency phase components at different sampling moments; and acquiring real-time frequency information of the weak power grid by adopting an open-loop detection mode. The method comprises the following steps: acquiring a voltage signal of a micro-grid system, and extracting a difference frequency phase based on the acquired voltage signal; adjusting the difference frequency phase component; and the real-time frequency information of the weak power grid is obtained by adopting an open-loop detection method, so that the frequency measurement method is simple, the error is small, and the real-time performance is high.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid detection, and in particular to a microgrid frequency detection method, system, equipment and medium. Background Art

[0002] In recent years, frequency has become one of the important indicators of power quality. In applications such as microgrid system automatic control, motor automatic control, and microcomputer measurement of electrical parameters, there are high requirements for the accuracy and real-time performance of dynamic measurement of microgrid frequency.

[0003] Common software frequency measurement methods mainly include algorithms based on voltage zero crossing, CROSS algorithm based on linear interpolation, Fourier algorithm and three-point frequency measurement method. Among them, the CROSS algorithm based on linear interpolation has a simple calculation process, but the measurement error is large. Although the Fourier algorithm has a good harmonic suppression effect, it has high requirements for synchronous sampling of signals and the algorithm is complex. The three-point frequency measurement method combines three-point curve fitting with multi-point absolute value compensation. It is not affected by the voltage zero crossing, but it loses the simplicity of the zero crossing method to a certain extent.

[0004] Therefore, how to provide a microgrid frequency detection method, system, equipment and medium is a problem that needs to be solved urgently. Summary of the invention

[0005] The embodiments of the present invention provide a microgrid frequency detection method, system, device and medium to solve the above-mentioned technical problems existing in the prior art.

[0006] In order to have a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended to be a general review, nor is it intended to identify key / important components or to delineate the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a preface to the detailed description that follows.

[0007] According to a first aspect of an embodiment of the present invention, a microgrid frequency detection method is provided.

[0008] In one embodiment, the microgrid frequency detection method includes:

[0009] Collect the voltage signal of the microgrid system and distinguish and mark it according to the voltage type of the three-phase grid;

[0010] Based on the collected voltage signal, the amplitude and phase of each phase voltage signal are extracted, the phasor expression of the three-phase grid voltage is constructed, and the difference frequency phase component is extracted through time domain analysis and coordinate transformation;

[0011] Based on the difference frequency phase components at different sampling moments, calculating the increase of the difference frequency phase components in the future;

[0012] The open-loop detection method is adopted to obtain the real-time frequency information of the weak power grid.

[0013] In one embodiment, based on the collected voltage signal, the amplitude and phase of each phase voltage signal are extracted, the phasor expression of the three-phase grid voltage is constructed, and the difference frequency phase is extracted through time domain analysis and coordinate transformation, which includes:

[0014] The voltage signals of the three-phase grid voltage are subjected to single-phase phase-locked operation respectively to obtain the amplitude and phase of each phase, and the phasor expression of the three-phase grid voltage is constructed;

[0015] Performing a positive sequence transformation on the three-phase grid voltage phasor expression by using the symmetrical component to obtain the phasor expression of the positive sequence component in the asymmetrical grid voltage;

[0016] The positive sequence components are respectively subjected to unidirectional reverse phase-locking operation to obtain a time domain expression of a negative sequence component in an asymmetric grid voltage;

[0017] Using the positive sequence component to perform three-phase open-loop phase locking in a rotating coordinate system, a real-time synchronous phase of the asymmetric grid voltage is obtained;

[0018] Based on the difference frequency phase tracking algorithm, the difference frequency phase component in the real-time synchronization phase is extracted.

[0019] In one embodiment, the expression of the real-time synchronization phase is:

[0020]

[0021] In the formula, is the real-time synchronization phase; θ is the initial phase angle of the grid voltage; θ * is the coordinate transformation angle; U d and U q They are the components of the three-phase voltage on the d and q axes of the rotating coordinate system respectively.

[0022] In one embodiment, the expression for extracting the difference frequency phase component in the real-time synchronization phase is:

[0023]

[0024] In the formula, is the difference frequency phase component; θ * is the coordinate transformation angle; U d and U q They are the components of the three-phase voltage on the d and q axes of the rotating coordinate system respectively.

[0025] In one embodiment, the calculating the increase of the future difference frequency phase component based on the difference frequency phase components at different sampling moments comprises:

[0026] Calculate the phase difference between the difference frequency phase component at the current sampling moment and the previous sampling moment, and compare the absolute value of the phase difference with a preset threshold;

[0027] If the absolute value of the phase difference is greater than a preset threshold, the difference frequency phase component is increased by (n-1)×2π starting from the current moment, where n is the periodic order.

[0028] In one embodiment, the method of acquiring the real-time frequency information of the weak power grid by adopting an open-loop detection method includes:

[0029] The feedback phase of the frequency open-loop detection is calculated by a linear relationship function between the difference frequency and the difference frequency phase component, and when the difference frequency phase component is equal to 0, the feedback phase is synchronized with the input phase;

[0030] The open-loop detection method is adopted to decompose the grid synchronization phase into the power frequency phase and the difference frequency phase. Combined with the feedback phase, the real-time frequency of the weak grid is calculated.

[0031] In one embodiment, the expression for calculating the real-time frequency of the weak power grid is:

[0032]

[0033] Where, f is the real-time frequency; f s is the power frequency phase; Δf out is the difference frequency; K p is the proportional control gain; K i is the integral control gain; is the difference frequency phase component.

[0034] According to a second aspect of an embodiment of the present invention, a microgrid frequency detection system is provided.

[0035] In one embodiment, the microgrid frequency detection system comprises:

[0036] The voltage acquisition module is used to collect the voltage signal of the microgrid system and distinguish and mark it according to the voltage type of the three-phase grid;

[0037] A phase conversion module is used to extract the amplitude and phase of each phase voltage signal based on the collected voltage signal, construct a phasor expression of the three-phase grid voltage, and extract the difference frequency phase component through time domain analysis and coordinate conversion;

[0038] An increment calculation module, used for calculating the increase of the future difference frequency phase component based on the difference frequency phase components at different sampling moments;

[0039] The frequency calculation module is used to obtain the real-time frequency information of the weak power grid by adopting an open-loop detection method.

[0040] In one embodiment, the phase conversion module includes: a single-phase phase locking module, a positive sequence conversion module, a single-phase reverse phase locking module, a coordinate conversion module and a phase tracking module, wherein:

[0041] The single-phase phase-locking module is used to perform single-phase phase-locking operations on the voltage signals of the three-phase grid voltage respectively, obtain the amplitude and phase of each phase, and construct a phasor expression of the three-phase grid voltage;

[0042] The positive sequence transformation module is used to perform positive sequence transformation on the three-phase grid voltage phasor expression using symmetrical components to obtain the phasor expression of the positive sequence component in the asymmetrical grid voltage;

[0043] The single-phase reverse phase-locking module is used to perform a one-way reverse phase-locking operation on the positive sequence components to obtain a time domain expression of the negative sequence components in the asymmetric grid voltage;

[0044] The coordinate conversion module is used to perform three-phase open-loop phase locking in a rotating coordinate system using the positive sequence component to obtain a real-time synchronous phase of the asymmetric grid voltage;

[0045] The phase tracking module is used to extract the difference frequency phase component in the real-time synchronization phase based on the difference frequency phase tracking algorithm.

[0046] In one embodiment, the expression of the real-time synchronization phase is:

[0047]

[0048] In the formula, is the real-time synchronization phase; θ is the initial phase angle of the grid voltage; θ * is the coordinate transformation angle; U d and U q They are the components of the three-phase voltage on the d and q axes of the rotating coordinate system respectively.

[0049] In one embodiment, the expression for extracting the difference frequency phase component in the real-time synchronization phase is:

[0050]

[0051] In the formula, is the difference frequency phase component; θ * is the coordinate transformation angle; U d and U q They are the components of the three-phase voltage on the d and q axes of the rotating coordinate system respectively.

[0052] In one embodiment, the increment calculation module includes: a difference calculation module and a threshold analysis module, wherein:

[0053] The difference calculation module is used to calculate the phase difference between the difference frequency phase component at the current sampling moment and the previous sampling moment, and compare the absolute value of the phase difference with a preset threshold;

[0054] The threshold analysis module is used to increase the difference frequency phase component by (n-1)×2π from the current moment if the absolute value of the phase difference is greater than a preset threshold, where n is the periodic order.

[0055] In one embodiment, the frequency calculation module includes: a linear calculation module and an open-loop detection module, wherein:

[0056] The linear calculation module is used to calculate the feedback phase of the frequency open-loop detection through the linear relationship function between the difference frequency and the difference frequency phase component. When the difference frequency phase component is equal to 0, the feedback phase is synchronized with the input phase;

[0057] The open-loop detection module is used to decompose the grid synchronization phase into a power frequency phase and a difference frequency phase by means of open-loop detection, and calculate the real-time frequency of the weak grid in combination with the feedback phase.

[0058] In one embodiment, the expression for calculating the real-time frequency of the weak power grid is:

[0059]

[0060] Where, f is the real-time frequency; f s is the power frequency phase; Δf out is the difference frequency; K p is the proportional control gain; K i is the integral control gain; is the difference frequency phase component.

[0061] According to a third aspect of an embodiment of the present invention, a computer device is provided.

[0062] In some embodiments, the computer device includes a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0063] According to a fourth aspect of embodiments of the present invention, a computer-readable storage medium is provided.

[0064] In one embodiment, the computer-readable storage medium stores a computer program, and the computer program implements the steps of the above method when executed by a processor.

[0065] The technical solution provided by the embodiment of the present invention may include the following beneficial effects: by collecting the voltage signal of the microgrid system, extracting the difference frequency phase based on the collected voltage signal; adjusting the difference frequency phase component; using the open-loop detection method to obtain the real-time frequency information of the weak power grid, which helps to simplify the frequency measurement method, reduce the error and have strong real-time performance.

[0066] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0068] Figure 1 is a flow chart of a microgrid frequency detection method according to an exemplary embodiment;

[0069] Figure 2 is a structural schematic diagram of a microgrid frequency detection system according to an exemplary embodiment;

[0070] Figure 3 The figure is a schematic diagram showing the structure of a computer device according to an exemplary embodiment.

[0071] Figure 4 This is the principle diagram of frequency closed-loop detection. DETAILED DESCRIPTION

[0072] The following description and accompanying drawings fully illustrate the specific embodiments of this article so that those skilled in the art can practice them. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. The scope of the embodiments of this article includes the entire scope of the claims, as well as all available equivalents of the claims. Herein, the terms "first", "second", etc. are only used to distinguish one element from another, without requiring or implying any actual relationship or order between these elements. In fact, the first element can also be called the second element, and vice versa. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the structure, device or equipment including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to such structure, device or equipment. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the structure, device or equipment including the elements. Each embodiment is described in a progressive manner herein, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other.

[0073] The terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. in this document indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this document and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of this document, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, it can also be the internal communication of two elements, it can be a direct connection, or it can be an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0074] As used herein, unless otherwise specified, the term "plurality" means two or more than two.

[0075] In this document, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0076] In this article, the term "and / or" is a description of the association relationship between objects, indicating that three relationships may exist. For example, A and / or B means: A or B, or, A and B.

[0077] It should be understood that, although the various steps in the flow chart are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0078] Each module in the device or system of the present application can be implemented in whole or in part by software, hardware, or a combination thereof. The above modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above modules.

[0079] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0080] Figure 1 An embodiment of a microgrid frequency detection method of the present invention is shown.

[0081] In this optional embodiment, the microgrid frequency detection method includes:

[0082] Step S101: Collect voltage signals of the microgrid system and distinguish and mark them according to the voltage types of the three-phase grid.

[0083] Step S103: based on the collected voltage signal, extract the amplitude and phase of each phase voltage signal, construct the phasor expression of the three-phase grid voltage, and extract the difference frequency phase component through time domain analysis and coordinate transformation.

[0084] Step S105: Calculate the increase of the future difference frequency phase component based on the difference frequency phase components at different sampling moments.

[0085] Step S107: using an open-loop detection method to obtain real-time frequency information of the weak power grid.

[0086] In this optional embodiment, based on the collected voltage signal, the amplitude and phase of each phase voltage signal are extracted to construct the phasor expression of the three-phase grid voltage. When the difference frequency phase is extracted through time domain analysis and coordinate transformation, the voltage signals of the three-phase grid voltage can be subjected to single-phase phase-locked operation respectively to obtain the amplitude and phase of each phase to construct the phasor expression of the three-phase grid voltage; the symmetrical components are used to perform positive sequence transformation on the phasor expression of the three-phase grid voltage to obtain the phasor expression of the positive sequence component in the asymmetric grid voltage; the positive sequence components are subjected to one-way inverse phase-locked operation respectively to obtain the time domain expression of the negative sequence component in the asymmetric grid voltage; the positive sequence components are used to perform three-phase open-loop phase locking in a rotating coordinate system to obtain the real-time synchronous phase of the asymmetric grid voltage; based on the difference frequency phase tracking algorithm, the difference frequency phase component in the real-time synchronous phase is extracted.

[0087] In this optional embodiment, the expression of the real-time synchronization phase is:

[0088]

[0089] In the formula, is the real-time synchronization phase; θ is the initial phase angle of the grid voltage; θ * is the coordinate transformation angle; U d and U q They are the components of the three-phase voltage on the d and q axes of the rotating coordinate system respectively.

[0090] In this optional embodiment, the expression for extracting the difference frequency phase component in the real-time synchronization phase is:

[0091]

[0092] In the formula, is the difference frequency phase component; θ * is the coordinate transformation angle; U d and U q They are the components of the three-phase voltage on the d and q axes of the rotating coordinate system respectively.

[0093] In this optional embodiment, when calculating the increase of the future difference frequency phase component based on the difference frequency phase component at different sampling moments, the phase difference between the difference frequency phase component at the current sampling moment and the previous sampling moment can be calculated, and the absolute value of the phase difference can be compared with a preset threshold; if the absolute value of the phase difference is greater than the preset threshold, then starting from the current moment, the difference frequency phase component is increased by (n-1)×2π, where n is the periodic order.

[0094] In this optional embodiment, when the open-loop detection method is used to obtain the real-time frequency information of the weak power grid, the feedback phase of the frequency open-loop detection can be calculated through the linear relationship function between the difference frequency and the difference frequency phase component. When the difference frequency phase component is equal to 0, the feedback phase is synchronized with the input phase. The open-loop detection method is used to decompose the power grid synchronization phase into the power frequency phase and the difference frequency phase, and the real-time frequency of the weak power grid is calculated in combination with the feedback phase.

[0095] In this optional embodiment, the expression for calculating the real-time frequency of the weak power grid is:

[0096]

[0097] Where, f is the real-time frequency; f s is the power frequency phase; Δf out is the difference frequency; K p is the proportional control gain; K i is the integral control gain; is the difference frequency phase component.

[0098] Figure 2 An embodiment of a microgrid frequency detection system of the present invention is shown.

[0099] In this optional embodiment, the microgrid frequency detection system includes:

[0100] The voltage acquisition module 201 is used to collect the voltage signal of the microgrid system and distinguish and mark it according to the voltage type of the three-phase grid.

[0101] The phase conversion module 203 is used to extract the amplitude and phase of each phase voltage signal based on the collected voltage signal, construct a phasor expression of the three-phase grid voltage, and extract the difference frequency phase component through time domain analysis and coordinate conversion.

[0102] The increment calculation module 205 is used to calculate the increase of the future difference frequency phase component based on the difference frequency phase components at different sampling moments.

[0103] The frequency calculation module 207 is used to obtain the real-time frequency information of the weak power grid by adopting an open-loop detection method.

[0104] In this optional embodiment, the phase conversion module 203 includes: a single-phase phase-locking module (not shown in the figure), a positive-sequence transformation module (not shown in the figure), a single-phase reverse phase-locking module (not shown in the figure), a coordinate conversion module (not shown in the figure) and a phase tracking module (not shown in the figure), wherein the single-phase phase-locking module is used to perform single-phase phase-locking operations on the voltage signals of the three-phase power grid voltage respectively, obtain the amplitude and phase of each phase, and construct the phasor expression of the three-phase power grid voltage; the positive-sequence transformation module is used to perform positive-sequence transformation on the phasor expression of the three-phase power grid voltage using symmetrical components to obtain the phasor expression of the positive-sequence component in the asymmetric power grid voltage; the single-phase reverse phase-locking module is used to perform unidirectional reverse phase-locking operations on the positive-sequence components respectively to obtain the time domain expression of the negative-sequence component in the asymmetric power grid voltage; the coordinate conversion module is used to perform three-phase open-loop phase locking in a rotating coordinate system using the positive-sequence component to obtain the real-time synchronous phase of the asymmetric power grid voltage; the phase tracking module is used to extract the difference frequency phase component in the real-time synchronous phase based on the difference frequency phase tracking algorithm.

[0105] In this optional embodiment, the expression of the real-time synchronization phase is:

[0106]

[0107] In the formula, is the real-time synchronization phase; θ is the initial phase angle of the grid voltage; θ * is the coordinate transformation angle; U d and U q They are the components of the three-phase voltage on the d and q axes of the rotating coordinate system respectively.

[0108] In this optional embodiment, the expression for extracting the difference frequency phase component in the real-time synchronization phase is:

[0109]

[0110] In the formula, is the difference frequency phase component; θ * is the coordinate transformation angle; U d and U q They are the components of the three-phase voltage on the d and q axes of the rotating coordinate system respectively.

[0111] In this optional embodiment, the incremental calculation module 205 includes: a difference calculation module (not shown in the figure) and a threshold analysis module (not shown in the figure), wherein the difference calculation module is used to calculate the phase difference between the difference frequency phase component at the current sampling moment and the previous sampling moment, and compare the absolute value of the phase difference with a preset threshold; the threshold analysis module is used to increase the difference frequency phase component by (n-1)×2π starting from the current moment if the absolute value of the phase difference is greater than the preset threshold, wherein n is the periodic order.

[0112] In this optional embodiment, the frequency calculation module 207 includes: a linear calculation module (not shown in the figure) and an open-loop detection module (not shown in the figure), wherein the linear calculation module is used to calculate the feedback phase of the frequency open-loop detection through a linear relationship function between the difference frequency and the difference frequency phase component, and when the difference frequency phase component is equal to 0, the feedback phase is synchronized with the input phase; the open-loop detection module is used to decompose the grid synchronization phase into the power frequency phase and the difference frequency phase by using an open-loop detection method, and calculate the real-time frequency of the weak grid in combination with the feedback phase.

[0113] In this optional embodiment, the expression for calculating the real-time frequency of the weak power grid is:

[0114]

[0115] Where, f is the real-time frequency; f s is the power frequency phase; Δf out is the difference frequency; K p is the proportional control gain; K i is the integral control gain; is the difference frequency phase component.

[0116] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0117] This embodiment provides a frequency detection method applied to a microgrid, comprising the following steps:

[0118] S1: Collect the voltage signal of the microgrid system and convert the voltage signal into u a 、u b and u c express.

[0119] S2: Extract the difference frequency phase based on the collected voltage signal.

[0120] S21: u a 、u b and u c The amplitude and phase of each phase can be obtained by performing single-phase phase-locking operations respectively, thereby constructing the phasor expression of the three-phase grid voltage, as shown below:

[0121]

[0122] Among them, U sm is the three-phase voltage amplitude of the power grid; θ is the initial phase angle of the power grid voltage;

[0123] S22: Perform Clarke transformation on the above expression to obtain the following expression:

[0124]

[0125] Among them, u sα and u sβ are the components of the three-phase voltage on the α and β axes of the stationary coordinate system;

[0126] S23: perform Park transformation again;

[0127]

[0128] Among them, U d and U q is the component of the three-phase voltage on the d and q axes of the rotating coordinate system, θ * is the coordinate transformation angle;

[0129]

[0130] S24: The synchronous phase of the grid voltage can be obtained by using the phase fast open-loop calculation method

[0131]

[0132] S25: Extracted by difference frequency phase tracking algorithm The difference frequency phase component in .

[0133]

[0134] S3: Adjust the difference frequency phase component.

[0135] Specifically, compare the difference frequency phase between the current sampling time t and the previous sampling time t-1. When the absolute value of the result is greater than m, the theoretical value of m is equal to 2π, and the difference frequency phase starting from time t needs to be increased by (n-1)×2π; where n is the period order, thus the adjusted

[0136]

[0137] S4: Use closed-loop detection method to obtain real-time frequency information of weak power grid.

[0138] like Figure 4 As shown, specifically, a closed-loop detection method is used to obtain real-time frequency information of a weak power grid; specifically, the following steps are included:

[0139] Let the difference frequency be Δf out , and The linear relationship function is used as the feedback phase θ of the frequency open loop detection back , which is in the form of:

[0140]

[0141] when When it is equal to 0, that is, the feedback phase is synchronized with the input phase, it can be expressed as Δf out =Δf, from which we can get:

[0142]

[0143] Among them, K p is the proportional control gain; K i is the integral control gain.

[0144] The open-loop detection method is used to synchronize the phase of the power grid Decomposed into power frequency phase f s Sum and Difference Phase Two parts, so the real-time frequency is:

[0145]

[0146] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Figure 3 As shown. The computer device includes a processor, a memory and a network interface connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store static information and dynamic information data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, the steps in the above method embodiment are implemented.

[0147] Those skilled in the art will understand that Figure 3 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present invention, and does not constitute a limitation on the computer device to which the solution of the present invention is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0148] In addition, the present invention also provides a computer device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above method embodiment when executing the computer program.

[0149] In addition, the present invention further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps in the above method embodiment are implemented.

[0150] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0151] The present invention is not limited to the structures which have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A microgrid frequency detection method, characterized in that: include: Collect the voltage signal of the microgrid system and distinguish and mark it according to the voltage type of the three-phase grid; Based on the collected voltage signal, the amplitude and phase of each phase voltage signal are extracted, the phasor expression of the three-phase grid voltage is constructed, and the difference frequency phase component is extracted through time domain analysis and coordinate transformation; Based on the difference frequency phase components at different sampling moments, calculating the increase of the difference frequency phase components in the future; The open-loop detection method is adopted to obtain the real-time frequency information of the weak power grid.

2. The microgrid frequency detection method according to claim 1, characterized in that: The step of extracting the amplitude and phase of each phase voltage signal based on the collected voltage signal, constructing a phasor expression of the three-phase grid voltage, and extracting the difference frequency phase through time domain analysis and coordinate transformation includes: The voltage signals of the three-phase grid voltage are subjected to single-phase phase-locked operation respectively to obtain the amplitude and phase of each phase, and the phasor expression of the three-phase grid voltage is constructed; Performing a positive sequence transformation on the three-phase grid voltage phasor expression by using the symmetrical component to obtain the phasor expression of the positive sequence component in the asymmetrical grid voltage; The positive sequence components are respectively subjected to unidirectional reverse phase-locking operation to obtain a time domain expression of a negative sequence component in an asymmetric grid voltage; Using the positive sequence component to perform three-phase open-loop phase locking in a rotating coordinate system, a real-time synchronous phase of the asymmetric grid voltage is obtained; Based on the difference frequency phase tracking algorithm, the difference frequency phase component in the real-time synchronization phase is extracted.

3. The microgrid frequency detection method according to claim 2, characterized in that: The expression of the real-time synchronization phase is: In the formula, is the real-time synchronization phase; θ is the initial phase angle of the grid voltage; θ * is the coordinate transformation angle; U d and U q They are the components of the three-phase voltage on the d and q axes of the rotating coordinate system respectively.

4. The microgrid frequency detection method according to claim 2, characterized in that: The expression for extracting the difference frequency phase component in the real-time synchronization phase is: In the formula, is the difference frequency phase component; θ * is the coordinate transformation angle; U d and U q They are the components of the three-phase voltage on the d and q axes of the rotating coordinate system respectively.

5. The microgrid frequency detection method according to claim 1, characterized in that: The step of calculating the increase of the future difference frequency phase component based on the difference frequency phase components at different sampling moments includes: Calculate the phase difference between the difference frequency phase component at the current sampling moment and the previous sampling moment, and compare the absolute value of the phase difference with a preset threshold; If the absolute value of the phase difference is greater than a preset threshold, the difference frequency phase component is increased by (n-1)×2π starting from the current moment, where n is the periodic order.

6. The microgrid frequency detection method according to claim 1, characterized in that: The method of using open loop detection to obtain real-time frequency information of a weak power grid includes: The feedback phase of the frequency open-loop detection is calculated by a linear relationship function between the difference frequency and the difference frequency phase component, and when the difference frequency phase component is equal to 0, the feedback phase is synchronized with the input phase; The open-loop detection method is adopted to decompose the grid synchronization phase into the power frequency phase and the difference frequency phase. Combined with the feedback phase, the real-time frequency of the weak grid is calculated.

7. The microgrid frequency detection method according to claim 6, characterized in that: The expression for calculating the real-time frequency of the weak power grid is: Where, f is the real-time frequency; f s is the power frequency phase; Δf out is the difference frequency; K p is the proportional control gain; K i is the integral control gain; is the difference frequency phase component.

8. A microgrid frequency detection system, characterized in that: include: The voltage acquisition module is used to collect the voltage signal of the microgrid system and distinguish and mark it according to the voltage type of the three-phase grid; A phase conversion module is used to extract the amplitude and phase of each phase voltage signal based on the collected voltage signal, construct a phasor expression of the three-phase grid voltage, and extract the difference frequency phase component through time domain analysis and coordinate conversion; An increment calculation module, used for calculating the increase of the future difference frequency phase component based on the difference frequency phase components at different sampling moments; The frequency calculation module is used to obtain the real-time frequency information of the weak power grid by adopting an open-loop detection method.

9. The microgrid frequency detection system according to claim 8, characterized in that: The phase conversion module includes: a single-phase phase-locking module, a positive sequence conversion module, a single-phase reverse phase-locking module, a coordinate conversion module and a phase tracking module, wherein: The single-phase phase-locking module is used to perform single-phase phase-locking operations on the voltage signals of the three-phase grid voltage respectively, obtain the amplitude and phase of each phase, and construct a phasor expression of the three-phase grid voltage; The positive sequence transformation module is used to perform positive sequence transformation on the three-phase grid voltage phasor expression using symmetrical components to obtain the phasor expression of the positive sequence component in the asymmetrical grid voltage; The single-phase reverse phase-locking module is used to perform a one-way reverse phase-locking operation on the positive sequence components to obtain a time domain expression of the negative sequence components in the asymmetric grid voltage; The coordinate conversion module is used to perform three-phase open-loop phase locking in a rotating coordinate system using the positive sequence component to obtain a real-time synchronous phase of the asymmetric grid voltage; The phase tracking module is used to extract the difference frequency phase component in the real-time synchronization phase based on the difference frequency phase tracking algorithm.

10. The microgrid frequency detection system according to claim 9, characterized in that: The expression of the real-time synchronization phase is: In the formula, is the real-time synchronization phase; θ is the initial phase angle of the grid voltage; θ * is the coordinate transformation angle; U d and U q They are the components of the three-phase voltage on the d and q axes of the rotating coordinate system respectively.

11. The microgrid frequency detection system according to claim 9, characterized in that: The expression for extracting the difference frequency phase component in the real-time synchronization phase is: In the formula, is the difference frequency phase component; θ * is the coordinate transformation angle; U d and U q They are the components of the three-phase voltage on the d and q axes of the rotating coordinate system respectively.

12. The microgrid frequency detection system according to claim 8, characterized in that: The incremental calculation module includes: a difference calculation module and a threshold analysis module, wherein: The difference calculation module is used to calculate the phase difference between the difference frequency phase component at the current sampling moment and the previous sampling moment, and compare the absolute value of the phase difference with a preset threshold; The threshold analysis module is used to increase the difference frequency phase component by (n-1)×2π starting from the current moment if the absolute value of the phase difference is greater than a preset threshold, where n is the periodic order.

13. The microgrid frequency detection system according to claim 8, characterized in that: The frequency calculation module includes: a linear calculation module and an open-loop detection module, wherein: The linear calculation module is used to calculate the feedback phase of the frequency open-loop detection through the linear relationship function between the difference frequency and the difference frequency phase component. When the difference frequency phase component is equal to 0, the feedback phase is synchronized with the input phase; The open-loop detection module is used to decompose the grid synchronization phase into a power frequency phase and a difference frequency phase by means of open-loop detection, and calculate the real-time frequency of the weak grid in combination with the feedback phase.

14. The microgrid frequency detection system according to claim 13, characterized in that: The expression for calculating the real-time frequency of the weak power grid is: Where, f is the real-time frequency; f s is the power frequency phase; Δf out is the difference frequency; K p is the proportional control gain; K i is the integral control gain; is the difference frequency phase component.

15. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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