Alternating current microgrid stability analysis method, device and equipment and storage medium

Abstract

The invention discloses an AC micro-grid stability analysis method, device and equipment and a storage medium, and the method comprises the steps: carrying out the steady-state modeling of an inverter under droop control in an AC micro-grid under the premise of considering the line loss and resistive and inductive loads, obtaining an active frequency equation set composed of the active frequency equations of all inverters, and carrying out the steady-state modeling of the inverter under droop control; and calculating a Jacobian matrix of the phase angle state equation of the active frequency equation set, calculating a non-zero characteristic value of the Jacobian matrix, and determining whether the frequency synchronization balance point of the AC micro-grid is stable based on the distribution state of the non-zero characteristic value of the Jacobian matrix. On the premise of considering line loss and resistive and inductive loads, steady-state modeling is carried out on the inverter under droop control in the alternating-current micro-grid, the stability problem of an active frequency equation set is converted into the Jacobian matrix eigenvalue analysis problem of a state equation of the inverter, and the accuracy of stability analysis of the alternating-current micro-grid is improved.

Description

Technical Field

[0001] The present invention relates to power grid technology, and in particular to an AC microgrid stability analysis method, device, equipment and storage medium. Background Art

[0002] The stability analysis of the frequency synchronization balance point is an important basic work for the synchronization state, safety, power balance and load sharing of the AC Microgrid system. The volatility of renewable energy and load can easily cause the system to lose its steady state, which is a huge challenge to the frequency synchronization stability of the AC Microgrid system. At the same time, the huge node scale and the loss effect caused by the resistive and inductive lines make the stability analysis of the synchronization frequency balance point of the AC Microgrid system more difficult.

[0003] At present, a lot of research and analysis have been carried out in the modeling and stability analysis of AC microgrids, mainly focusing on the special case of lossless AC microgrids and each node containing an inverter, without considering line losses and nodes containing loads, resulting in low accuracy of existing AC microgrid stability analysis. Summary of the invention

[0004] The present invention provides an AC microgrid stability analysis method, device, equipment and storage medium to improve the accuracy of AC microgrid stability analysis.

[0005] In a first aspect, the present invention provides an AC microgrid stability analysis method, comprising:

[0006] Under the premise of considering line loss and resistive and inductive loads, a steady-state model is performed on the inverter under droop control in the AC microgrid to obtain an active frequency equation group consisting of active frequency equations of each inverter;

[0007] Calculating the Jacobian matrix of the phase angle state equation of the active frequency equation group;

[0008] Calculate the non-zero eigenvalues ​​of the Jacobian matrix;

[0009] Whether the frequency synchronization balance point of the AC microgrid is stable is determined based on the distribution state of the non-zero eigenvalues ​​of the Jacobian matrix.

[0010] Optionally, under the premise of considering line loss and resistive and inductive loads, steady-state modeling is performed on the inverter under droop control in the AC microgrid to obtain an active frequency equation group consisting of active frequency equations of each inverter, including:

[0011] The inverter under droop control is equivalent to a controlled voltage source, and an active frequency control equation of the inverter is determined;

[0012] Modeling the AC microgrid as a directed graph with a plurality of nodes, wherein the node represents the inverter or the resistive inductive load;

[0013] Determine an active power expression of each inverter based on the relationship between the admittance matrix of the directed graph and each of the nodes;

[0014] An active frequency equation group consisting of active frequency equations of each inverter is determined based on the active frequency control equation of the inverter and the active power expression of the inverter.

[0015] Optionally, the active frequency control equation of the inverter is:

[0016] θ i =ω i -m i p i

[0017] Among them, θ i ,ω i , m i and p i are the phase angle frequency, no-load frequency, droop control coefficient and the power injected into the grid of the i-th inverter.

[0018] Optionally, the active power expression of each inverter is:

[0019]

[0020] Among them, V i Indicates the power of the inverter, a ij for a ij +jb ij The phase angle, c ij for a ij +jb ij The modulus, θ i is the phase angle frequency of the i-th inverter.

[0021] Optionally, the active frequency equation group formed by the active frequency equations of each inverter is:

[0022] θ=ω1 n -KP

[0023] Where ω is a constant, K = diag{kp1,…,kp n}, p i is the active power of the ith inverter, k is a constant, 1 n Represents an n-dimensional vector whose elements are 1.

[0024] Optionally, the Jacobian matrix of the phase angle state equation of the active frequency equation group is:

[0025]

[0026] Among them, the diagonal elements e ii and the off-diagonal elements e iz The expressions are as follows:

[0027]

[0028] e iz =V i V z c iz sin(θ i -θ z +α iz )

[0029] Among them, V i Indicates the power of the inverter, a ij for a ij +jb ij The phase angle, c ij for a ij +jb ij The modulus, θ i is the phase angle frequency of the i-th inverter.

[0030] Optionally, determining whether the frequency synchronization balance point of the AC microgrid is stable based on the distribution state of the non-zero eigenvalues ​​of the Jacobian matrix includes:

[0031] Determine whether the non-zero eigenvalues ​​of the Jacobian matrix are located in the upper triangular region of the Jacobian matrix;

[0032] If so, it is determined that the frequency synchronization balance point of the AC microgrid is stable;

[0033] If not, it is determined that the frequency synchronization balance point of the AC microgrid is unstable.

[0034] In a second aspect, the present invention further provides an AC microgrid stability analysis device, comprising:

[0035] A steady-state modeling module is used to perform steady-state modeling on the inverter under droop control in the AC microgrid under the premise of considering line loss and resistive and inductive loads, and obtain an active frequency equation group consisting of active frequency equations of each of the inverters;

[0036] A Jacobian matrix calculation module, used for calculating the Jacobian matrix of the phase angle state equation of the active frequency equation group;

[0037] An eigenvalue calculation module, used for calculating the non-zero eigenvalues ​​of the Jacobian matrix;

[0038] The stability judgment module is used to judge whether the frequency synchronization balance point of the AC microgrid is stable based on the distribution state of the non-zero eigenvalues ​​of the Jacobian matrix.

[0039] In a third aspect, the present invention further provides an electronic device, comprising:

[0040] one or more processors;

[0041] A storage device for storing one or more programs;

[0042] When the one or more programs are executed by the one or more processors, the one or more processors implement the AC microgrid stability analysis method provided in the first aspect of the present invention.

[0043] In a fourth aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the AC microgrid stability analysis method provided in the first aspect of the present invention.

[0044] The AC microgrid stability analysis method provided by the present invention performs steady-state modeling on the inverter under droop control in the AC microgrid under the premise of considering line loss and resistive inductive load, obtains an active frequency equation group consisting of active frequency equations of each inverter, calculates the Jacobian matrix of the phase angle state equation of the active frequency equation group, calculates the non-zero eigenvalues ​​of the Jacobian matrix, and determines whether the frequency synchronization balance point of the AC microgrid is stable based on the distribution state of the non-zero eigenvalues ​​of the Jacobian matrix. Under the premise of considering line loss and resistive inductive load, the inverter under droop control in the AC microgrid is modeled in a steady state, and the stability problem of the active frequency equation group is converted into the Jacobian matrix eigenvalue analysis problem of its state equation, thereby improving the accuracy of the stability analysis of the AC microgrid.

[0045] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0047] Figure 1 A flow chart of an AC microgrid stability analysis method provided by the present invention;

[0048] Figure 2 A schematic diagram of the structure of an AC microgrid stability analysis device provided by the present invention;

[0049] Figure 3 The present invention provides a schematic structural diagram of an electronic device.

[0050] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0051] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0052] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0053] Figure 1 This is a flow chart of an AC microgrid stability analysis method provided by the present invention. This embodiment can be applied to AC microgrid stability analysis. The method can be executed by an AC microgrid stability analysis device provided by the present invention. The device can be implemented by software and / or hardware, and is usually configured in an electronic device, such as Figure 1 As shown in FIG. 1 , the AC microgrid stability analysis method specifically includes the following steps:

[0054] S101. Under the premise of considering line loss and resistive and inductive loads, steady-state modeling is performed on the inverter under droop control in the AC microgrid to obtain an active frequency equation group consisting of active frequency equations of each inverter.

[0055] In general, a large-scale network can be modeled as a directed graph G(V,E) with q nodes, where V = {1,2,…,q} is the set of nodes and E = V×V is the set of edges. represents the relationship between each node and edge, |E| is the cardinality of E, where if node i is the outgoing end of edge (i,z), then b iz =1; if node i is the incident end of edge (i,z), then b iz = -1; otherwise b iz = 0. The edge weight diagonal matrix is The Laplace matrix of graph G is L = B T AB.

[0056] Assume that in a conventional AC microgrid, there are n inverters under droop control and m resistive and inductive loads consisting of resistors and inductors, respectively. The inverter under droop control can be equivalent to a controlled voltage source, and its active frequency control equation is given by (1):

[0057] θ i =ω i -m i p i (1)

[0058] Among them, θ i ,ω i , m i and p i are the phase angle frequency, no-load frequency, droop control coefficient and power injected into the grid of the i-th inverter. The no-load frequency is usually 50HZ or 60HZ.

[0059] In order to establish the complete active frequency control equation, the active power p injected into the network by the i-th inverter node will be established next. i In fact, the AC microgrid can be modeled as a graph G(V,E), where V = {V I ,V L},V I ={1,…,n},V L ={1,…,m}, where V I is the set of inverter nodes, V L is the set of load nodes. Then, the admittance matrix of the network can be expressed as Where A and B are the edge weight diagonal matrix and incidence matrix of graph G respectively. where r iz and x iz are the impedance and inductive reactance of edge (i, z) respectively. Next, rewrite the admittance matrix Y as formula (2):

[0060]

[0061] in The relationship between the current and voltage between nodes can be given by equation (3):

[0062]

[0063] in Represent the voltages of all inverter nodes and the current injected into the network, They represent the voltage of all load nodes and the current injected into the network. In addition, the current of the load node also satisfies the relationship (4):

[0064]

[0065] in r load,i and x load,i They are load i∈V L The impedance and inductive reactance of the load. Equation (4) represents the current drawn by the load from the network. Combining equations (3) and (4), we can get equation (5):

[0066]

[0067] Substituting formula (5) into formula (3) and simplifying it, we get formula (6):

[0068] I S =Y eq U S

[0069]

[0070] Y eq Rewrite equation (7) in argument form:

[0071]

[0072] in Therefore, the apparent power of all inverter nodes is Given by formula (8):

[0073]

[0074] Y eq * Rewrite as formula (9):

[0075]

[0076] in c iz =czi ,α iz =α zi ,α iz ∈[-π,π] is a ij +jb ij The phase angle.

[0077] Taking the real part of formula (8) we get the expression (10) of the inverter active power P:

[0078]

[0079] Define K = diag{kp1,…,kp n} and θ=[θ1,…,θ n ] T , combined with equation (1), we get the active frequency equation group (11) consisting of the active frequency equations of each inverter:

[0080] θ=ω1 n -KP (11)

[0081] Among them, ω=50Hz is a constant, K=diag{kp1,…,kp n}, p i is the active power of the ith inverter, k is a constant, 1 n Represents an n-dimensional vector whose elements are 1.

[0082] S102. Calculate the Jacobian matrix of the phase angle state equation of the active frequency equation group.

[0083] Definition 1 Frequency synchronization: For the active frequency equations (11), frequency synchronization means:

[0084]

[0085] That is where ω syc The synchronization frequency is constant.

[0086] Definition 2 If a matrix All off-diagonal elements of are negative or 0, and all diagonal elements are positive, then the matrix A is called a Z matrix. If the absolute value of the main diagonal elements in each row (column) is greater than or equal to the sum of the absolute values ​​of other off-diagonal elements in the row (column), then the matrix B is a diagonally dominant matrix.

[0087] Lemma 1 If the matrix C is both diagonally dominant and a Z matrix, then the matrix All eigenvalues ​​of are non-negative, but the opposite is not necessarily true.

[0088] But in fact, the active frequency equation group (11) is a model of the inverter phase angle in the AC microgrid. The active frequency equation group (11) can only analyze the stability of the phase angle, but cannot deduce the stability of the phase angle difference between inverters, that is, the stability of the frequency synchronization balance point. Next, we will prove that the non-zero eigenvalues ​​of the Jacobian matrix of the inverter phase angle state equation are completely consistent with the eigenvalues ​​of the Jacobian matrix of the phase angle difference state equation between inverters, that is, the stability of the inverter frequency synchronization balance point can be judged by the non-zero eigenvalues ​​of the Jacobian matrix of the inverter phase angle state space.

[0089] First, define the matrix is the Jacobian matrix of the state equation of the active frequency equation group (11), and its block is shown in equation (12):

[0090]

[0091] in Then the linearized state space (13) of the active frequency equation group (11) is obtained:

[0092]

[0093] In an AC microgrid with n inverters, there are n phase angle variables, but in fact there are only n-1 sets of independent phase angle difference variables. Therefore, the phase angle difference variable It is defined as shown in formula (14):

[0094]

[0095] Taking the derivative of equation (14) and combining it with equation (13) we get equation (15):

[0096]

[0097] By transforming formula (15), we can get its equivalent form (16):

[0098]

[0099] Substituting equation (16) into equation (14), we obtain the linearized state space of phase angle difference (17):

[0100]

[0101] In fact, to determine the stability of the frequency synchronization equilibrium point of the active frequency equation group (11), it is necessary to determine the eigenvalue of the Jacobian matrix of its phase difference state equation, that is, the Jacobian matrix J 11 -1 n-1 J 21 Is the real part of the eigenvalue of in the upper triangle area? Next we will prove that J 11-1 n-1 J 21 The eigenvalues ​​of are exactly the same as the non-zero eigenvalues ​​of J. Define the matrix N:

[0102]

[0103] The eigenvalue of J is calculated as shown in (19):

[0104] |λI n-1 -J|=0 (19)

[0105] Multiplying both sides of equation (19) by matrix N and simplifying it, we get equation (20):

[0106]

[0107] Since the determinant of matrix N is 1, the operation of equation (20) does not affect the calculation of the eigenvalue of J. Since the row sum of matrix J is 0, the last column of the second matrix in equation (20) is 0. After simplifying (20), the characteristic equation of the phase angle (21) is obtained:

[0108] λ|λI n-1 -(J 11 -1 n-1 J 21 )|=0 (21)

[0109] Obviously, one eigenvalue is equal to 0, and the rest is exactly the matrix J 11 -1 n-1 J 21 This shows that the eigenvalues ​​of the phase difference Jacobian matrix are completely consistent with the non-zero eigenvalues ​​of the phase angle Jacobian matrix. Therefore, the stability of the frequency synchronization balance point of all nodes of the inverter can be explained by studying the non-zero eigenvalues ​​of the Jacobian matrix of the state equation of the phase angle of the inverter node itself.

[0110] The Jacobian matrix J of the active frequency equation group (11) is calculated as follows:

[0111]

[0112] The diagonal elements e ii and the off-diagonal elements e iz The expressions are as follows

[0113]

[0114] e iz =V i V z c iz sin(θ i -θ z +αiz ) (twenty three)

[0115] Among them, V i Indicates the power of the inverter, a ij for a ij +jb ij The phase angle, c ij for a ij +jb ij The modulus, θ i is the phase angle frequency of the i-th inverter.

[0116] According to formula (23), it is not difficult to deduce that the row sum of J is 0. From the above, it can be seen that the stability of the phase difference considered by the synchronous frequency balance point is equivalent to analyzing the non-zero eigenvalues ​​of the Jacobian matrix of its phase state equation, that is, analyzing the non-zero eigenvalues ​​of formula (22).

[0117] S103. Calculate the non-zero eigenvalues ​​of the Jacobian matrix.

[0118] In the embodiment of the present invention, the non-zero eigenvalues ​​of the Jacobian matrix are calculated, and the calculation formula can refer to formula (19).

[0119] S104. Determine whether the frequency synchronization balance point of the AC microgrid is stable based on the distribution state of the non-zero eigenvalues ​​of the Jacobian matrix.

[0120] Exemplarily, determining whether the non-zero eigenvalue of the Jacobian matrix is ​​located in the upper triangular region of the Jacobian matrix;

[0121] If so, it is determined that the frequency synchronization balance point of the AC microgrid is stable;

[0122] If not, it is determined that the frequency synchronization balance point of the AC microgrid is unstable.

[0123] Theorem 1 If the frequency synchronization equilibrium point of the active frequency equation group (11) satisfies condition (24), then the equilibrium point is stable.

[0124] (θ i -θ z +α iz )∈[0±2kπ,π±2kπ] (24)

[0125] in k is an integer.

[0126] Proof: The frequency synchronization equilibrium point of the active frequency equation group (11) has small signal stability, which is equivalent to that all non-zero eigenvalues ​​of its Jacobian matrix J are located in the upper triangular region.

[0127] Now it is known that the row sum of matrix J is 0. According to Definition 2, we know that J is a diagonally dominant matrix. From Lemma 1, we know that as long as J is also a Z matrix, all eigenvalues ​​of J are non-negative, that is, it is necessary to ensure that the diagonal of J is positive and the off-diagonal is non-positive, and then condition (24) is derived.

[0128] The AC microgrid stability analysis method provided by the present invention performs steady-state modeling on the inverter under droop control in the AC microgrid under the premise of considering line loss and resistive inductive load, obtains an active frequency equation group consisting of active frequency equations of each inverter, calculates the Jacobian matrix of the phase angle state equation of the active frequency equation group, calculates the non-zero eigenvalues ​​of the Jacobian matrix, and determines whether the frequency synchronization balance point of the AC microgrid is stable based on the distribution state of the non-zero eigenvalues ​​of the Jacobian matrix. Under the premise of considering line loss and resistive inductive load, the inverter under droop control in the AC microgrid is modeled in a steady state, and the stability problem of the active frequency equation group is converted into the Jacobian matrix eigenvalue analysis problem of its state equation, thereby improving the accuracy of the stability analysis of the AC microgrid.

[0129] Figure 2 A schematic diagram of the structure of an AC microgrid stability analysis device provided by the present invention is shown in FIG. Figure 2 As shown, the AC microgrid stability analysis device includes:

[0130] The steady-state modeling module 201 is used to perform steady-state modeling on the inverter under droop control in the AC microgrid under the premise of considering line loss and resistive and inductive loads, and obtain an active frequency equation group consisting of active frequency equations of each of the inverters;

[0131] A Jacobian matrix calculation module 202, used for calculating the Jacobian matrix of the phase angle state equation of the active frequency equation group;

[0132] An eigenvalue calculation module 203 is used to calculate the non-zero eigenvalues ​​of the Jacobian matrix;

[0133] The stability judgment module 204 is used to judge whether the frequency synchronization balance point of the AC microgrid is stable based on the distribution state of the non-zero eigenvalues ​​of the Jacobian matrix.

[0134] In some embodiments of the present invention, the steady-state modeling module 201 includes:

[0135] An active frequency control equation determination submodule, used to treat the inverter under droop control as equivalent to a controlled voltage source, and determine the active frequency control equation of the inverter;

[0136] A directed graph construction submodule, used for modeling the AC microgrid as a directed graph with a plurality of nodes, wherein the nodes represent the inverter or the resistive-inductive load;

[0137] An active power expression determination submodule, used to determine the active power expression of each inverter based on the relationship between the admittance matrix of the directed graph and each of the nodes;

[0138] The active frequency control equation group determination submodule is used to determine the active frequency equation group consisting of the active frequency equations of each inverter based on the active frequency control equation of the inverter and the active power expression of the inverter.

[0139] In some embodiments of the present invention, the active frequency control equation of the inverter is:

[0140] θ i =ω i -m i p i

[0141] Among them, θ i ,ω i , m i and p i are the phase angle frequency, no-load frequency, droop control coefficient and the power injected into the grid of the i-th inverter.

[0142] In some embodiments of the present invention, the active power expression of each inverter is:

[0143]

[0144] Among them, V i Indicates the power of the inverter, a ij for a ij +jb ij The phase angle, c ij for a ij +jb ij The modulus, θ i is the phase angle frequency of the i-th inverter.

[0145] In some embodiments of the present invention, the active frequency equation group formed by the active frequency equations of each inverter is:

[0146] θ=ω1 n -KP

[0147] Where ω is a constant, K = diag{kp1,…,kp n}, p i is the active power of the ith inverter, k is a constant, 1 n Represents an n-dimensional vector whose elements are 1.

[0148] In some embodiments of the present invention, the Jacobian matrix of the phase angle state equation of the active frequency equation group is:

[0149]

[0150] Among them, the diagonal elements e ii and the off-diagonal elements e iz The expressions are as follows:

[0151]

[0152] e iz =V i V z c iz sin(θ i -θ z +α iz )

[0153] Among them, V i Indicates the power of the inverter, a ij for a ij +jb ij The phase angle, c ij for a ij +jb ij The modulus, θ i is the phase angle frequency of the i-th inverter.

[0154] In some embodiments of the present invention, the stability determination module 204 includes:

[0155] A judgment submodule, used to judge whether the non-zero eigenvalue of the Jacobian matrix is ​​located in the upper triangular area of ​​the Jacobian matrix;

[0156] A stability determination submodule, used for determining whether the frequency synchronization balance point of the AC microgrid is stable when the non-zero eigenvalue of the Jacobian matrix is ​​located in the upper triangular region of the Jacobian matrix;

[0157] The instability determination submodule is used to determine that the frequency synchronization balance point of the AC microgrid is unstable when the non-zero eigenvalue of the Jacobian matrix is ​​not located in the upper triangular area of ​​the Jacobian matrix.

[0158] The above-mentioned AC microgrid stability analysis device can execute the AC microgrid stability analysis method provided by the aforementioned embodiment of the present invention, and has corresponding functional modules and beneficial effects for executing the AC microgrid stability analysis method.

[0159] Figure 3A schematic diagram of the structure of an electronic device provided by the present invention. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0160] like Figure 3 As shown, the electronic device includes at least one processor 11, and a memory connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 to the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0161] A number of components in the electronic device are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0162] The processor 11 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as the AC microgrid stability analysis method.

[0163] In some embodiments, the AC microgrid stability analysis method may be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program may be loaded and / or installed on an electronic device via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the AC microgrid stability analysis method described above may be performed. Alternatively, in other embodiments, the processor 11 may be configured to perform the AC microgrid stability analysis method in any other appropriate manner (e.g., by means of firmware).

[0164] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0165] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0166] In the context of the present invention, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in combination with an instruction execution system, device or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0167] To provide interaction with a user, the systems and techniques described herein may be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form (including acoustic input, voice input, or tactile input).

[0168] The systems and techniques described herein may be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0169] A computing system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

[0170] An embodiment of the present invention further provides a computer program product, including a computer program, which, when executed by a processor, implements the AC microgrid stability analysis method provided in any embodiment of the present application.

[0171] In the process of implementation, the computer program product can be written in one or more programming languages ​​or a combination thereof to perform the computer program code of the present invention, including object-oriented programming languages, such as Java, Smalltalk, C++, and conventional procedural programming languages, such as "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (for example, using an Internet service provider to connect through the Internet).

[0172] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0173] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for analyzing the stability of an AC microgrid, characterized in that: include: Under the premise of considering line loss and resistive and inductive loads, a steady-state model is performed on the inverter under droop control in the AC microgrid to obtain an active frequency equation group consisting of active frequency equations of each inverter; Calculating the Jacobian matrix of the phase angle state equation of the active frequency equation group; Calculate the non-zero eigenvalues ​​of the Jacobian matrix; Whether the frequency synchronization balance point of the AC microgrid is stable is determined based on the distribution state of the non-zero eigenvalues ​​of the Jacobian matrix.

2. The AC microgrid stability analysis method according to claim 1, characterized in that: Under the premise of considering line loss and resistive and inductive loads, the inverter under droop control in the AC microgrid is modeled in a steady state, and an active frequency equation group consisting of active frequency equations of each inverter is obtained, including: The inverter under droop control is equivalent to a controlled voltage source, and an active frequency control equation of the inverter is determined; Modeling the AC microgrid as a directed graph with a plurality of nodes, wherein the node represents the inverter or the resistive inductive load; Determine an active power expression of each inverter based on the relationship between the admittance matrix of the directed graph and each of the nodes; An active frequency equation group consisting of active frequency equations of each inverter is determined based on the active frequency control equation of the inverter and the active power expression of the inverter.

3. The AC microgrid stability analysis method according to claim 2, characterized in that: The active frequency control equation of the inverter is: i i =ω i -m i p i Among them, θ i ,ω i , m i and p i are the phase angle frequency, no-load frequency, droop control coefficient and the power injected into the grid of the i-th inverter.

4. The AC microgrid stability analysis method according to claim 2, characterized in that: The active power expression of each inverter is: Among them, V i Indicates the power of the inverter, a ij for a ij +jb ij The phase angle, c ij for a ij +jb ij The modulus, θ i is the phase angle frequency of the i-th inverter.

5. The AC microgrid stability analysis method according to claim 2, characterized in that: The active frequency equation group formed by the active frequency equations of each inverter is: θ=ω1 n -KP Where ω is a constant, K = diag{kp1,…,kp n }, p i is the active power of the ith inverter, k is a constant, 1 n Represents an n-dimensional vector whose elements are 1.

6. The AC microgrid stability analysis method according to claim 1, characterized in that: The Jacobian matrix of the phase angle state equation of the active frequency equation group is: Among them, the diagonal elements e ii and the off-diagonal elements e iz The expressions are as follows: e iz =V i V z c iz sin(θ i -θ z +a iz ) Among them, V i Indicates the power of the inverter, a ij for a ij +jb ij The phase angle, c ij for a ij +jb ij The modulus, θ i is the phase angle frequency of the i-th inverter.

7. The AC microgrid stability analysis method according to claim 1, characterized in that: Determining whether the frequency synchronization balance point of the AC microgrid is stable based on the distribution state of the non-zero eigenvalues ​​of the Jacobian matrix includes: Determine whether the non-zero eigenvalues ​​of the Jacobian matrix are located in the upper triangular region of the Jacobian matrix; If so, it is determined that the frequency synchronization balance point of the AC microgrid is stable; If not, it is determined that the frequency synchronization balance point of the AC microgrid is unstable.

8. An AC microgrid stability analysis device, characterized in that: include: A steady-state modeling module is used to perform steady-state modeling on the inverter under droop control in the AC microgrid under the premise of considering line loss and resistive and inductive loads, and obtain an active frequency equation group consisting of active frequency equations of each of the inverters; A Jacobian matrix calculation module, used for calculating the Jacobian matrix of the phase angle state equation of the active frequency equation group; An eigenvalue calculation module, used for calculating the non-zero eigenvalues ​​of the Jacobian matrix; The stability judgment module is used to judge whether the frequency synchronization balance point of the AC microgrid is stable based on the distribution state of the non-zero eigenvalues ​​of the Jacobian matrix.

9. An electronic device, characterized in that: include: one or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the AC microgrid stability analysis method as described in any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the AC microgrid stability analysis method as described in any one of claims 1 to 7 is implemented.

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