Power low-frequency switching flexible load control method, system, equipment and medium

Abstract

The invention belongs to the technical field of power system load control, and discloses a power low frequency-to-flexible load control method, system and device and a medium, and the method comprises the following steps: building a power system node frequency model; performing node frequency solution based on the power system node frequency model to obtain node frequency weight matrix information; constructing a load removal model of the new energy power system, and solving the load removal model of the new energy power system to obtain flexible load power expected to be removed by the power system; and each node flexible load on-site device performs on-site power control on the flexible load according to the optimal distribution result. According to the method, starting from the mechanism of the system frequency space-time distribution characteristics, frequency models of a synchronous machine, loads, new energy and the like are established, main indexes influencing the node frequency are explained, and a low-frequency-to-flexible-load strategy for reducing the system frequency deviation and improving the system stability is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of power system load control, and in particular to a method, system, equipment and medium for controlling low-frequency flexible loads of electric power. Background Art

[0002] At present, intermittent renewable energy sources such as wind, solar and photovoltaic will gradually change from secondary energy sources to primary energy sources in the power system, and a large number of synchronous generators on the power supply side are gradually being replaced by power electronic equipment. Compared with traditional synchronous machines, new energy sources such as wind power basically do not provide inertia, resulting in the dynamic deterioration of the frequency of the new power system after suffering severe power disturbances, which has a bad impact on the safety, stability and economic operation of the power grid.

[0003] As the third line of defense of the power system, low-frequency load shedding is an effective method to suppress frequency drop and maintain system frequency stability. The traditional low-frequency load shedding scheme adopts a successive approximation calculation method to cut off the pre-set load according to the action frequency of each round to ensure the balance between demand and power generation, thereby ensuring system stability and restoring the frequency to the allowable range. However, due to the reduction of system inertia, the probability of triggering low-frequency load shedding increases, and the above research cannot fundamentally reduce the economic losses caused by low-frequency load shedding measures to the power grid.

[0004] Flexible loads, such as constant temperature loads such as air conditioners, can reduce average power consumption through on / off control, thereby providing grid frequency support in a shorter period of time. However, due to the decentralized characteristics of flexible loads, the determination of the removal location and removal amount still needs further study.

[0005] Due to factors such as grid structure, distribution of generator sets, unit parameters and load type, the system frequency presents spatiotemporal distribution characteristics. In particular, the uneven distribution of system inertia caused by the access of new energy sources makes the spatiotemporal distribution characteristics of system frequency increasingly significant. Many experts and scholars at home and abroad have conducted relevant research on this, proposed some characterization and quantification methods for system frequency response characteristics, and performed inertia evaluation and inertia configuration based on the spatiotemporal distribution characteristics of the system, thereby improving the frequency stability of each node in the whole system. However, few literatures consider the spatiotemporal characteristics of system frequency after load shedding. But in fact, due to the removal of loads at different positions, new impacts will be generated on the system frequency, and some nodes may further increase the frequency deviation, which will have new adverse effects on system stability.

[0006] Therefore, how to provide a method, system, equipment and medium for controlling low-frequency flexible load shedding of electric power is a problem that needs to be solved urgently. Summary of the invention

[0007] The embodiments of the present invention provide a method, system, device and medium for controlling low-frequency flexible load shedding of electric power to solve the problems in the prior art.

[0008] 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.

[0009] According to a first aspect of an embodiment of the present invention, a method, system, device and medium for controlling low-frequency flexible load shedding of electric power are provided.

[0010] In one embodiment, a method for controlling low-frequency flexible load shedding of electric power comprises the following steps:

[0011] Obtain power data of the power system, and establish a power system node frequency model based on the power system node frequency generation mechanism; solve the node frequency based on the power system node frequency model to obtain the node frequency weight matrix information;

[0012] The initial distribution of electromagnetic power is carried out based on the electrical distance between the power source and the location where the disturbance occurs. According to the initial distribution result and combined with the spatiotemporal distribution characteristics of the frequency, a load shedding model of the new energy power system is constructed. By solving the load shedding model of the new energy power system, the flexible load power expected to be shelved by the power system is obtained.

[0013] According to the node frequency weight matrix information and the flexible load power that the power system expects to remove, the flexible load removal power is optimized and allocated, and the optimized allocation result is transmitted to the flexible load local device at each node; the flexible load local device at each node performs local power control on the flexible load according to the optimized allocation result.

[0014] In one embodiment, node frequency is solved based on the power system node frequency model to obtain node frequency weight matrix information including:

[0015] The expression of the power system node frequency model is differentiated with respect to time, and the differentiation result is Laplace transformed to obtain the relationship function between the node frequency and the synchronous power supply speed;

[0016] In a synchronous AC power system, the node frequency is solved based on the relationship between the rotor angle and the speed of the synchronous power supply and the relationship between the node voltage phase angle and the node frequency, and combined with the relationship function between the node frequency and the speed of the synchronous power supply, and the node frequency weight matrix information is determined based on the node frequency.

[0017] In one embodiment, the initial allocation of electromagnetic power based on the electrical distance between the power source and the location where the disturbance occurs includes:

[0018] Calculate the active output column vector of equivalent load based on the frequency response characteristics similar to grid-type renewable energy and load;

[0019] According to the similar frequency response characteristics of grid-forming new energy and synchronous machine, the active output column vector of equivalent power supply is calculated;

[0020] Based on the active output column vector of equivalent load, the active output column vector of equivalent power source and the power system node frequency model, the change of the instantaneous electromagnetic power of the synchronous power source is calculated, and the change of the instantaneous electromagnetic power of the synchronous power source is used as the initially allocated disturbance power.

[0021] In one embodiment, based on the initial allocation result and in combination with the spatiotemporal distribution characteristics of the frequency, a load shedding model of the new energy power system is constructed, and by solving the load shedding model of the new energy power system, the flexible load power expected to be shelved by the power system is obtained, including the following steps:

[0022] According to the initial allocation results and combined with the spatial and temporal distribution characteristics of the frequency, an objective function and power constraint conditions are established to minimize the difference between the disturbance power initially allocated by the equivalent synchronous power source and the disturbance power allocated by the equivalent synchronous power source according to its inertia size.

[0023] According to the objective function and power constraints, the flexible load power that the power system expects to remove is solved.

[0024] According to a second aspect of an embodiment of the present invention, there is provided an electric power low-frequency shedding flexible load control system.

[0025] In one embodiment, a power low-frequency shedding flexible load control system includes:

[0026] The node frequency weight matrix information calculation module is used to obtain the power data of the power system and establish a power system node frequency model based on the power system node frequency generation mechanism; the node frequency is solved based on the power system node frequency model to obtain the node frequency weight matrix information;

[0027] The flexible load power calculation module expected to be removed is used to perform the initial allocation of electromagnetic power based on the electrical distance between the power source and the location where the disturbance occurs. According to the initial allocation result and in combination with the spatiotemporal distribution characteristics of the frequency, a load removal model of the new energy power system is constructed. By solving the load removal model of the new energy power system, the flexible load power expected to be removed by the power system is obtained.

[0028] The local power control module is used to optimize the allocation of flexible load removal power according to the node frequency weight matrix information and the flexible load power that the power system expects to remove, and transmit the optimized allocation result to the local device of the flexible load at each node; the local device of the flexible load at each node performs local power control on the flexible load according to the optimized allocation result.

[0029] In one embodiment, node frequency is solved based on the power system node frequency model to obtain node frequency weight matrix information including:

[0030] The expression of the power system node frequency model is differentiated with respect to time, and the differentiation result is Laplace transformed to obtain the relationship function between the node frequency and the synchronous power supply speed;

[0031] In a synchronous AC power system, the node frequency is solved based on the relationship between the rotor angle and the speed of the synchronous power supply and the relationship between the node voltage phase angle and the node frequency, and combined with the relationship function between the node frequency and the speed of the synchronous power supply, and the node frequency weight matrix information is determined based on the node frequency.

[0032] In one embodiment, the initial allocation of electromagnetic power based on the electrical distance between the power source and the location where the disturbance occurs includes:

[0033] Calculate the active output column vector of equivalent load based on the frequency response characteristics similar to grid-type renewable energy and load;

[0034] According to the similar frequency response characteristics of grid-forming new energy and synchronous machine, the active output column vector of equivalent power supply is calculated;

[0035] Based on the active output column vector of equivalent load, the active output column vector of equivalent power source and the power system node frequency model, the change of the instantaneous electromagnetic power of the synchronous power source is calculated, and the change of the instantaneous electromagnetic power of the synchronous power source is used as the initially allocated disturbance power.

[0036] In one embodiment, according to the initial allocation result and in combination with the spatiotemporal distribution characteristics of the frequency, a load shedding model of the new energy power system is constructed, and by solving the load shedding model of the new energy power system, the flexible load power that the power system expects to shear includes:

[0037] According to the initial allocation results and combined with the spatial and temporal distribution characteristics of the frequency, an objective function and power constraint conditions are established to minimize the difference between the disturbance power initially allocated by the equivalent synchronous power source and the disturbance power allocated by the equivalent synchronous power source according to its inertia size.

[0038] According to the objective function and power constraints, the flexible load power that the power system expects to remove is solved.

[0039] According to a third aspect of an embodiment of the present invention, a computer device is provided.

[0040] 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.

[0041] According to a fourth aspect of embodiments of the present invention, a computer-readable storage medium is provided.

[0042] In one embodiment, a computer program is stored on a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0043] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0044] Starting from the mechanism of the spatiotemporal distribution characteristics of system frequency, the present invention establishes frequency models of synchronous machines, loads, and new energy sources, explains the main indicators that affect the node frequency, and proposes a low-frequency flexible load shedding strategy to reduce system frequency deviation and improve system stability.

[0045] 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

[0046] 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.

[0047] Figure 1 is a flow chart of a method for controlling low-frequency flexible load shedding of electric power according to an exemplary embodiment;

[0048] Figure 2 It is a principle block diagram of a power low-frequency shedding flexible load control system according to an exemplary embodiment;

[0049] Figure 3 is a structural schematic diagram of a computer device according to an exemplary embodiment;

[0050] Figure 4 is a schematic diagram of a typical system model including new energy in a method for controlling low-frequency flexible load shedding of electric power according to an exemplary embodiment;

[0051] Figure 5 A low-frequency flexible load cutting control process in a method for controlling a low-frequency flexible load in an electric power system is shown according to an exemplary embodiment;

[0052] Figure 6It is a system wiring diagram of an IEEE39 example in a power low-frequency flexible load shedding control method according to an exemplary embodiment;

[0053] Figure 7 It is a schematic diagram of a load shedding power distribution scheme in a method for controlling a low-frequency flexible load shedding of electric power according to an exemplary embodiment;

[0054] Figure 8 is a schematic diagram of node frequency comparison in a method for controlling low-frequency flexible load shedding of electric power according to an exemplary embodiment;

[0055] Fig. 9 is a schematic diagram showing a comparison of node frequency change rates in a method for controlling low-frequency flexible load shedding of electric power according to an exemplary embodiment;

[0056] Fig.10 It is a schematic diagram showing the comparison of maximum frequency deviations of each node after load shedding in a method for controlling low-frequency flexible load shedding of electric power according to an exemplary embodiment;

[0057] Fig.11 It is a comparison of the maximum frequency change rate of each node in a power low-frequency flexible load shedding control method according to an exemplary embodiment;

[0058] Fig.12 It is a schematic diagram showing the simulation comparison results of the speeds of various synchronous machines in a method for controlling low-frequency flexible load shedding of electric power according to an exemplary embodiment. DETAILED DESCRIPTION

[0059] 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 includes other elements that are not explicitly listed, or also includes 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.

[0060] 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.

[0061] As used herein, the term "plurality" means two or more than two, unless otherwise specified.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0067] Figure 1 An embodiment of the method for controlling low-frequency flexible load shedding of electric power according to the present invention is shown.

[0068] In this optional embodiment, the power low-frequency flexible load cutting control method includes the following steps:

[0069] Step S101, acquiring power data of the power system, and establishing a power system node frequency model based on the power system node frequency generation mechanism; solving the node frequency based on the power system node frequency model to obtain node frequency weight matrix information;

[0070] Step S103, performing initial distribution of electromagnetic power based on the electrical distance between the power source and the location where the disturbance occurs, constructing a load shedding model of the new energy power system based on the initial distribution result and in combination with the spatiotemporal distribution characteristics of the frequency, and solving the load shedding model of the new energy power system to obtain the flexible load power that the power system expects to shear off;

[0071] Step S105, based on the node frequency weight matrix information and the flexible load power that the power system expects to remove, the flexible load removal power is optimized and allocated, and the optimized allocation result is transmitted to the flexible load local device of each node; the flexible load local device of each node performs local power control on the flexible load according to the optimized allocation result.

[0072] In this optional embodiment, the expression of the power system node frequency model is:

[0073] B EG (δ EG -θ)-P ELN (I+K EL f)-P CL =B0θ

[0074] In the formula, B EG represents the diagonal array of susceptance in the equivalent power supply, δ EG represents the equivalent power source rotor angle column vector, θ represents the voltage phase angle vector of each node in the power system, P ELN represents the column vector of the rated active power absorbed by the equivalent load, I represents the unit vector, K EL represents the column vector of the active power regulation effect coefficient of the equivalent load, f represents the node frequency, P CL It represents the active power actually absorbed by the flexible load, and B0 represents the node susceptance matrix of the power system.

[0075] In this optional embodiment, when the node frequency is solved based on the power system node frequency model to obtain the node frequency weight matrix information, the expression of the power system node frequency model can be differentiated with respect to time, and the differentiation result can be Laplace transformed to obtain the relationship function between the node frequency and the synchronous power supply speed; in the synchronous AC power system, based on the relationship between the rotor angle and the speed of the synchronous power supply and the relationship between the node voltage phase angle and the node frequency, and combined with the relationship function between the node frequency and the synchronous power supply speed, the node frequency is solved, and the node frequency weight matrix information is determined based on the node frequency.

[0076] In this optional embodiment, when initially distributing electromagnetic power based on the electrical distance between the power source and the location where the disturbance occurs, the equivalent load active output column vector can be calculated based on the frequency response characteristics similar to those of the grid-following new energy and the load; the equivalent power source active output column vector can be calculated based on the frequency response characteristics similar to those of the grid-forming new energy and the synchronous machine; the change in the instantaneous electromagnetic power of the synchronous power source is calculated based on the equivalent load active output column vector, the equivalent power source active output column vector and the power system node frequency model, and the change in the instantaneous electromagnetic power of the synchronous power source is used as the initially distributed disturbance power.

[0077] In this optional embodiment, the calculation formula for the change in the instantaneous electromagnetic power of the synchronous power supply is:

[0078] ΔP EG =W T ΔP CL

[0079] Where ΔP EG Indicates the change in instantaneous electromagnetic power of the synchronous power supply, W T The transposed matrix of the weight matrix representing the node frequency, ΔPCL represents the flexible load disturbance vector.

[0080] In this optional embodiment, based on the initial allocation results and in combination with the spatiotemporal distribution characteristics of the frequency, a load shedding model of the new energy power system is constructed, and by solving the load shedding model of the new energy power system to obtain the flexible load power that the power system expects to shelve, an objective function and power constraints are established based on the initial allocation results and in combination with the spatiotemporal distribution characteristics of the frequency to minimize the difference between the disturbance power initially allocated by the equivalent synchronous power source and the disturbance power allocated by the equivalent synchronous power source according to its inertia size; and based on the objective function and the power constraints, the flexible load power that the power system expects to shelve is solved.

[0081] In this optional embodiment, the expression of the objective function and power constraint condition for minimizing the difference between the disturbance power initially allocated by the equivalent synchronous power source and the disturbance power allocated by the equivalent synchronous power source according to its inertia size is:

[0082]

[0083] ΔP CLimin ≤ΔP CLi ≤ΔP CLimax ,i=1,2,…,n

[0084]

[0085] Where ΔP EGj represents the disturbance power initially distributed by the jth equivalent synchronous power source, ΔP Hj represents the disturbance power allocated to the jth equivalent synchronous power source according to its inertia size, m represents the number of equivalent synchronous power sources in the power system, ΔP CLimin and ΔP Climax They represent the minimum and maximum power of the flexible adjustment of the i-th node in the power system, n represents the number of nodes in the power system, ΔP CLi represents the flexible power adjustment of the ith node in the power system, P exp It indicates the flexible load power that the power system expects to remove.

[0086] In order to facilitate understanding of the above technical solutions of the present invention, the above technical solutions of the present invention are further described below from the perspective of architecture and principle, as follows:

[0087] The present invention proposes a low-frequency flexible load shedding control strategy considering the spatiotemporal distribution characteristics: first, starting from the generation mechanism of the spatiotemporal distribution characteristics of frequency, a system node frequency model is established; then, considering the influence of the disturbance position on the initial power distribution of each synchronous machine, a low-frequency load shedding strategy is proposed to reduce the spatiotemporal distribution characteristics of frequency by adjusting the load shedding size at different positions; finally, the IEEE39 model is simulated and verified using power system simulation software (such as DlgSILENT\PowerFactory software), and the simulation results prove the superiority of this strategy.

[0088] 1. Based on the mechanism of node frequency generation, a simplified model of network, power supply and load is established to provide a theoretical basis for the analysis in subsequent chapters.

[0089] a. Network Model

[0090] In order to analyze the instantaneous frequency construction mechanism of the power system, the power system frequency response analysis method based on DC power flow is used, and the network model can be simplified as follows:

[0091] P=Bθ

[0092] Where: P represents the net active power injection vector of each node, B represents the power system susceptance matrix, and θ represents the voltage phase angle vector of each node.

[0093] From the principle of frequency divider, we can know that in the synchronous AC power system, the frequency of each node is generated by the rotation speed of each synchronous power source, that is, the active power-phase angle network equation can be expressed as:

[0094] PG-PL=B0θ

[0095] Where P G represents the active output column vector of synchronous power supply, P L represents the load active output column vector, B represents the power system susceptance matrix, and θ represents the voltage phase angle vector of each node.

[0096] b. Synchronous machine model

[0097] The external characteristics of the synchronous machine are voltage sources. The external characteristics of the synchronous machine are voltage sources. Ignoring the stator winding resistance of the synchronous power supply and the salient pole effect of the unit, assuming that the internal potential and the terminal voltage of the synchronous machine are 1.0, the active output P of the synchronous machine is G It can be expressed as:

[0098] P G =B G (δ-θ)

[0099] Where P G represents the active output column vector of synchronous power supply, B Grepresents the internal susceptance of the synchronous machine; δ represents the rotor angle of the synchronous machine; θ represents the phase angle vector of the voltage at the machine end.

[0100] c. Load model

[0101] The load simplified model only considers the static active power model of its frequency regulation effect, which can be expressed as:

[0102] P L =P LN (1+K L Δf)

[0103] Where P L Indicates the active power actually absorbed by the load, P LN Indicates the active power absorbed by the load at rated voltage and frequency, K L It represents the load active power regulation effect coefficient, and Δf represents the frequency deviation.

[0104] The power of the flexible load is adjusted according to the user temperature. In order to simplify the calculation, the frequency regulation effect can be ignored in this paper, which is equivalent to a constant power load model, that is, K L =0, which can be expressed as:

[0105] P CL =P CLN

[0106] Where P CL Indicates the active power actually absorbed by the flexible load, P CLN Indicates the active power absorbed by the flexible load at rated voltage and frequency.

[0107] d. New energy equivalent model

[0108] (1) Grid-connected new energy

[0109] For grid-connected new energy, its external characteristics are shown as a current source, so its simplified model can be expressed as:

[0110] P GFL =P GFLN (1-K GFL Δf)

[0111] Where P GFL Indicates the actual output of the grid-type power supply, P GFLN Indicates the rated output of the grid-type power supply, K GFL It represents the active power regulation effect coefficient of the grid-type power supply, and Δf is the frequency offset of the node where the grid-type power supply is located.

[0112] (2) Network-building new energy

[0113] For grid-building new energy, its external characteristics are voltage sources, so its simplified model can be expressed as:

[0114] P GFM =B GFM (δ GFM -θ)

[0115] Where P GFM Indicates the actual output of the grid-type power supply, δ GFM The virtual rotor angle of the grid type, B GFM represents the virtual internal susceptance of the grid-type power supply, and θ represents the node voltage phase angle.

[0116] Therefore, if Figure 4 As shown, the network equation of the typical system node frequency model containing new energy can be expressed as:

[0117] P G +P GFM +P GFL -P L -P CL =B0θ

[0118] Where P G represents the active output column vector of synchronous power supply, P GFM Indicates the actual output of the grid-type power supply, P GFL Indicates the actual output of the grid-type power supply, P L Indicates the active power actually absorbed by the load, P CL represents the active power actually absorbed by the flexible load, B0 represents the node susceptance matrix of the power system, and θ represents the voltage phase angle vector of each node in the power system.

[0119] Figure 4 In the formula, GFL stands for grid-following power source, GFM stands for grid-forming power source, L stands for common load, CL stands for controllable load, G stands for synchronous machine, and B stands for 12 , B 23 Respectively represent the susceptance between nodes 1 and 2 and between nodes 2 and 3, B G , B GFM They represent the internal susceptance of the synchronous machine and the equivalent internal susceptance of the grid-type power supply respectively.

[0120] Among them, the power system node susceptance matrix B0 is:

[0121]

[0122] In addition, it can be seen from the expressions of the simplified load model and the grid-following new energy that the grid-following new energy and the load have similar frequency response characteristics. In order to simplify the calculation, they can be combined to obtain the equivalent load active output column vector, which can be expressed as:

[0123] P EL =PL -P GFL =P ELN (I+K EL f)

[0124]

[0125] Where P EL Represents the active output column vector of equivalent load, P L Indicates the active power actually absorbed by the load, P GFL Indicates the actual output of the grid-type power supply, P ELN represents the column vector of the rated active power absorbed by the equivalent load, I represents the unit vector, K EL represents the column vector of the active power regulation effect coefficient of the equivalent load, and f represents the node frequency.

[0126] Similarly, according to the synchronous machine model expression and the grid-connected new energy expression, it can be seen that the grid-connected new energy and the synchronous machine have similar frequency response characteristics. In order to simplify the calculation, they can be combined, and the equivalent power source active output column vector P EG It is expressed as:

[0127] P EG =P G +P GFM =B EG (δ EG -θ)

[0128]

[0129] Where P EG Represents the active output column vector of the equivalent power supply, P G represents the active output column vector of synchronous power supply, P GFM Indicates the actual output of the grid-type power supply, B EG represents the diagonal array of susceptance in the equivalent power supply, δ EG represents the equivalent power source rotor angle column vector, θ represents the voltage phase angle vector of each node in the power system, B EG,j represents the internal susceptance diagonal matrix of the jth equivalent power supply, B G,j represents the diagonal array of susceptance in the jth synchronous machine, B GFM,j represents the virtual internal susceptance diagonal array of the j-th grid-type power source, δ EG,j represents the rotor angle column vector of the jth equivalent power supply, δ j represents the rotor angle column vector of the jth synchronous machine, δ GFM,j Represents the virtual rotor angle column vector of the j-th grid-type power supply.

[0130] Substituting the equivalent load active output column vector expression and the equivalent power source active output column vector expression into the network equation of the typical system node frequency model containing new energy, the optimized network equation of the typical system node frequency model containing new energy can be obtained:

[0131] P EG -P EL -P CL =B0θ

[0132] B EG (δ EG -θ)-P ELN (I+K EL f)-P CL =B0θ

[0133] Where P EG Represents the active output column vector of the equivalent power supply, P CL Indicates the active power actually absorbed by the flexible load, P EL represents the column vector of the equivalent load active output, B0 represents the node susceptance matrix of the power system, θ represents the voltage phase angle vector of each node in the power system, B EG represents the diagonal array of susceptance in the equivalent power supply, δ EG represents the equivalent power rotor angle column vector, P ELN represents the column vector of the rated active power absorbed by the equivalent load, I represents the unit vector, K EL represents the column vector of the active power regulation effect coefficient of the equivalent load, f represents the node frequency, P CL Indicates the active power actually absorbed by the flexible load.

[0134] In a synchronous AC power system, the rotor angle δ of the synchronous power source is related to the speed f G , and the node voltage phase angle θ and the node frequency f satisfy the following relationship:

[0135]

[0136] The network equation of the optimized typical system node frequency model containing new energy is differentiated with respect to time and Laplace transformed, and the relationship between the node frequency and the synchronous power supply speed can be obtained as follows:

[0137] f(s)=W(s)f EG (s)

[0138] W(s)=(B0+B EG +sK EL P ELN ) -1 B EG

[0139]

[0140] Where W represents the weight matrix of node frequency, w ij represents the influence weight of the power supply at node j on the frequency of node i, f(s) represents the frequency domain expression of the node frequency, W(s) represents the frequency domain form of the weight matrix of the node frequency, f EG (s) represents the frequency domain expression of the equivalent power supply speed, B0 represents the power system node susceptance matrix, B EG represents the diagonal array of susceptance in the equivalent power supply, K EL Represents the column vector of the active power regulation effect coefficient of the equivalent load, P ELN represents the column vector of rated active power absorbed by the equivalent load, and s represents the complex variable in Laplace transform.

[0141] Specifically, by performing an inverse Laplace transform on the relationship expression between the node frequency and the synchronous power supply rotation speed, the time domain expression of the node frequency can be obtained.

[0142] 2. Based on the above theoretical analysis, by considering the spatiotemporal distribution characteristics of frequency, a load shedding model of the new energy power system is established, including the optimization objective function of reducing node frequency deviation, the flexible load shedding power allocation method and the optimization solution process.

[0143] 2.1. Initial perturbation allocation

[0144] When a disturbance occurs in the system, the initial disturbance is distributed according to the electrical distance between the power source and the location where the disturbance occurs. The specific details are as follows: Substituting the column vector expression of the active output of the equivalent power source into the optimized network equation of the typical system node frequency model containing new energy, we can obtain:

[0145]

[0146] Substituting the above formula into the equivalent power source active output column vector expression, we get:

[0147] P EG =P G +P GFM

[0148] =B EG [I-(B0+B EG ) -1 B EG ]δ EG

[0149] +B EG (B0+B EG ) -1 (P EL +P CL )

[0150] =BEG (IW)δ EG +W T (P EL +P CL )

[0151] Therefore, when the system flexible load generates ΔP CL When there is a disturbance of magnitude, the change in the instantaneous electromagnetic power of the synchronous power supply ΔP can be obtained. EG for:

[0152] ΔP EG =W T ΔP CL

[0153] In the formula, ΔP EG Indicates the change in instantaneous electromagnetic power of the synchronous power supply, W T represents the transposed matrix of the weight matrix representing the node frequency, ΔP CL represents the flexible load disturbance vector.

[0154] The above formula shows that when a power disturbance occurs in the power system, the unbalanced electromagnetic power will be distributed according to the frequency weight of the synchronous power source at the node where the disturbance occurs.

[0155] 2.2. From the analysis of 2.1, it can be seen that the process of cutting flexible loads at low frequencies can be equivalent to the disturbance of load reduction, and the distribution of the initial power of each synchronous power source will be carried out according to the expression of the change in the instantaneous electromagnetic power of the synchronous power source. From the mechanism of the frequency-time-space characteristics, it can be seen that the ratio of the inertia size of the synchronous power source does not match the distribution ratio of the node frequency weight matrix W, which ultimately leads to a large deviation in the frequency of each node. Therefore, this paper will optimize the above problems by reasonably distributing the power removal of flexible loads at different locations and reducing the deviation between the two ratios. The objective function can be expressed as:

[0156]

[0157]

[0158] In the formula, ΔP EGj represents the disturbance power initially distributed by the jth equivalent synchronous power source, ΔP Hj represents the disturbance power allocated to the jth equivalent synchronous power source according to its inertia size, m represents the number of equivalent synchronous power sources in the power system, and w ij represents the influence weight of the power supply at node j on the frequency of node i, n represents the number of nodes in the power system, ΔP CLi represents the flexible power adjustment of the i-th node in the power system, H j Represents the inertia of the jth equivalent synchronous power supply.

[0159] Among them, the adjustable flexible load power of each node ΔP CLi Certain power constraints need to be met, which can be expressed as:

[0160] ΔP CLimin ≤ΔP CLi ≤ΔP CLimax ,i=1,2,…,n

[0161]

[0162] ΔP CLimin and ΔP Climax They represent the minimum and maximum power of the flexible adjustment of the i-th node in the power system, n represents the number of nodes in the power system, ΔP CLi represents the flexible power adjustment of the ith node in the power system, P exp It indicates the flexible load power that the power system expects to remove.

[0163] The flexible load power that the power system expects to remove can be calculated by the following formula:

[0164]

[0165] Where P exp represents the flexible load power that the power system expects to remove, κ L Indicates the equivalent load frequency regulation coefficient of the power system, Δf * Indicates the per-unit value of the deviation between the stable frequency value after load shedding and the rated frequency, f ss and f N Respectively represent the stable frequency value after load reduction and the nominal value of the rated frequency, ΔP L represents the disturbance size, P LN represents the total active power of the system load, κ i Indicates the equivalent load frequency regulation coefficient, P LNi Indicates the power of the i-th load.

[0166] Among them, the disturbance size ΔP L It can be estimated from the system inertia center frequency:

[0167]

[0168] In the formula, H COI and f COI Represents COI inertia and COI frequency, ΔP L represents the disturbance size, m represents the number of equivalent synchronous power sources in the system, H j represents the inertia of the jth equivalent synchronous power supply, f irepresents the frequency of the jth equivalent synchronous power supply node, and t represents the time.

[0169] Ideally, after the flexible load is removed, the synchronous power supply should share the disturbance according to its inertia ratio, that is, ΔP EG =ΔP H , substituting it into the expression of the change in the instantaneous electromagnetic power of the synchronous power supply, we get:

[0170] ΔP H =W T ΔP CL

[0171] In the formula, ΔP H Indicates that W T represents the transposed matrix of the weight matrix representing the node frequency, ΔP CL represents the flexible load disturbance vector.

[0172] 3. Low frequency flexible load shedding control strategy

[0173] The control strategy flow of low-frequency flexible load shedding is as follows: Figure 5 As shown, a two-layer control architecture is adopted, the upper layer is the load control center, and the lower layer is the load local control device.

[0174] The upper load control center receives information such as the system admittance matrix, power data, and load data to solve the node frequency and obtain the node frequency weight matrix information. By solving the power inertia and COI frequency, the expected load reduction is calculated using the power expression of the flexible load that the power system expects to remove. After that, the load control center optimizes the allocation of the flexible load removal power based on the node frequency weight matrix, the expected load reduction, and the expected load reduction of each node flexible load, and sends the allocation results to the local flexible load devices at each node.

[0175] The functions of the lower-level load local control device mainly include three parts: flexible load operation status awareness, adjustable power evaluation and power control. Flexible load operation status awareness refers to the load local control device using measuring devices to achieve real-time monitoring of indoor and outdoor temperature, weather, load operating power, rated power, node frequency and other information; adjustable power evaluation refers to the load local control device evaluating the adjustable power of the flexible load based on the monitored data, taking into account factors such as user comfort and economic operation, and regularly sending the evaluation results to the upper-level load control center; load power control is the load local control device performing local power control on the flexible load based on the power command issued by the upper-level load control center.

[0176] Among them, the communication between the load control center and the local control device is realized through the 4G / 5G cloud platform. Since the status information such as indoor and outdoor temperature, weather, load operating power, etc. will not change suddenly in a short time, the load adjustable power evaluation cycle can be set longer, which is set to 5 minutes in this paper. When a disturbance occurs, the load control center can calculate according to the evaluation results of the previous cycle to improve the calculation efficiency. The node frequency and load reduction instructions have high real-time requirements, and the 4G / 5G cloud platform can meet the control requirements of this paper.

[0177] 4. To verify the effectiveness of the low-frequency flexible load shedding proposed in this paper, the IEEE39 model is used for simulation verification in DIgSILENT\PowerFactory. On the basis of the original standard model, the synchronous machines at nodes 33 and 38 are replaced with grid-following power supplies of equal capacity, and the synchronous machine at node 39 is replaced with a grid-forming power supply of equal capacity. The system wiring diagram is shown in the figure. Figure 6 As shown, 1-39 represent 39 bus nodes, WT1 represents a grid-forming power source, WT2 and WT3 represent grid-following power sources, and G2, G3, G5, G6, G7, G8, and G10 represent synchronous machines.

[0178] The present invention uses a sudden increase in load to demonstrate the frequency change in the transient process of the example system. When the time domain simulation is 2s, the load power of node 4 is suddenly increased by 500MW. Figure 7 Two load shedding schemes are given as follows:

[0179] (1) Solution 1: Centrally remove the high-power load at node 20.

[0180] (2) Scheme 2: Based on the load shedding scheme proposed in this paper: Evaluate the flexible loads on nodes 8, 16, 20, and 29, and set the flexible load adjustment power with the minimum frequency deviation of each node as the optimization goal.

[0181] System node frequency simulation results comparison Figure 8-11 As shown, Figure 8 For the comparison of frequency changes of each node, Fig. 9 is the comparison of the maximum frequency change rate of each node, Fig.10 This is the comparison of the maximum frequency deviation of each node after load shedding. Fig.11 is the comparison of the maximum frequency change rate of each node after load shedding. Figure 8-9It can be seen that after cutting off the same size of load, the frequency deviation and frequency change rate deviation of each node caused by concentrated load shedding in Scheme 1 are both large, and the maximum frequency change rate deviation of the node after load shedding is higher than the deviation caused by the disturbance, which has a bad impact on the system; while after Scheme 2 considers the spatiotemporal distribution characteristics of the nodes, the frequency deviation and frequency change rate deviation of each node caused are significantly reduced, and the system steady-state frequency caused by Scheme 2 is 49.91Hz, while that of Scheme 1 is 49.88Hz, which proves the superiority of Scheme 2.

[0182] Depend on Figure 10-11 Further comparison shows that the maximum frequency deviation of each node in Scheme 2 is reduced by 65.01% compared with Scheme 1, and the maximum deviation of the frequency change rate of each node is reduced by 54.39%. The spatiotemporal distribution characteristics of the frequency are significantly weakened, which prevents the load shedding from causing a greater impact on the system frequency, and improves the frequency stability of the system.

[0183] At the same time, the speed of each synchronous machine is compared and analyzed, such as Fig.12 As shown in the figure, the speed deviation of each synchronous machine after load shedding in Scheme 1 is obvious. It is particularly important to note that the minimum speed of some synchronous machines is lower than the minimum speed before load shedding, which has a more serious impact on the synchronous machine. However, the speed deviation of each synchronous machine in Scheme 2 is significantly reduced, and the minimum speed is higher than the speed before load shedding, which is conducive to the safe and stable operation of the synchronous machine.

[0184] In summary, this paper starts from the mechanism of the spatiotemporal distribution characteristics of system frequency, establishes frequency models of synchronous machines, loads, and new energy, explains the main indicators that affect the node frequency, and proposes a low-frequency flexible load shedding strategy to reduce system frequency deviation and improve system stability. The conclusions are as follows:

[0185] (1) The node frequency is obtained by superimposing the speed changes of each synchronous machine according to the weight matrix and is only related to the network topology.

[0186] (2) The initial node power disturbance is distributed according to the electrical distance, and the mismatch with the inertia size of the synchronous machine causes the deviation of the frequency of each node.

[0187] (3) The low-frequency flexible load shedding strategy proposed in this paper can greatly reduce the secondary impact of load shedding measures on the system frequency by considering the spatiotemporal distribution characteristics of the system frequency, improve the consistency of the frequency of each node, and verify the effectiveness and superiority of the strategy through simulation.

[0188] Figure 2 An embodiment of an electric power low-frequency shedding flexible load control system of the present invention is shown.

[0189] In this optional embodiment, the electric power low-frequency shedding flexible load control system includes:

[0190] The node frequency weight matrix information calculation module 201 is used to obtain the power data of the power system, and establish a node frequency model of the power system based on the node frequency generation mechanism of the power system; solve the node frequency based on the node frequency model of the power system to obtain the node frequency weight matrix information;

[0191] The flexible load power calculation module 203 expected to be removed is used to perform the initial allocation of electromagnetic power based on the electrical distance between the power source and the location where the disturbance occurs, and to construct a load removal model of the new energy power system based on the initial allocation result and in combination with the spatiotemporal distribution characteristics of the frequency, and to obtain the flexible load power expected to be removed by the power system by solving the load removal model of the new energy power system;

[0192] The local power control module 205 is used to optimize the allocation of flexible load removal power based on the node frequency weight matrix information and the flexible load power that the power system expects to remove, and transmit the optimized allocation result to the local device of the flexible load at each node; the local device of the flexible load at each node performs local power control on the flexible load according to the optimized allocation result.

[0193] In this optional embodiment, the expression of the power system node frequency model is:

[0194] B EG (δ EG -θ)-P ELN (I+K EL f)-P CL =B0θ

[0195] In the formula, B EG represents the diagonal array of susceptance in the equivalent power supply, δ EG represents the equivalent power source rotor angle column vector, θ represents the voltage phase angle vector of each node in the power system, P ELN represents the column vector of the rated active power absorbed by the equivalent load, I represents the unit vector, K EL represents the column vector of the active power regulation effect coefficient of the equivalent load, f represents the node frequency, P CL It represents the active power actually absorbed by the flexible load, and B0 represents the node susceptance matrix of the power system.

[0196] In this optional embodiment, the node frequency is solved based on the power system node frequency model to obtain the node frequency weight matrix information including:

[0197] The expression of the power system node frequency model is differentiated with respect to time, and the differentiation result is Laplace transformed to obtain the relationship function between the node frequency and the synchronous power supply speed;

[0198] In a synchronous AC power system, the node frequency is solved based on the relationship between the rotor angle and the speed of the synchronous power supply and the relationship between the node voltage phase angle and the node frequency, and combined with the relationship function between the node frequency and the speed of the synchronous power supply, and the node frequency weight matrix information is determined based on the node frequency.

[0199] In this optional embodiment, the initial distribution of electromagnetic power based on the electrical distance between the power source and the location where the disturbance occurs includes:

[0200] Calculate the active output column vector of equivalent load based on the frequency response characteristics similar to grid-type renewable energy and load;

[0201] According to the similar frequency response characteristics of grid-forming new energy and synchronous machine, the active output column vector of equivalent power supply is calculated;

[0202] Based on the active output column vector of equivalent load, the active output column vector of equivalent power source and the power system node frequency model, the change of the instantaneous electromagnetic power of the synchronous power source is calculated, and the change of the instantaneous electromagnetic power of the synchronous power source is used as the initially allocated disturbance power.

[0203] In this optional embodiment, the calculation formula for the change in the instantaneous electromagnetic power of the synchronous power supply is:

[0204] ΔP EG =W T ΔP CL

[0205] Where ΔP EG Indicates the change in instantaneous electromagnetic power of the synchronous power supply, W T represents the transposed matrix of the weight matrix representing the node frequency, ΔP CL represents the flexible load disturbance vector.

[0206] In this optional embodiment, according to the initial allocation result and in combination with the spatiotemporal distribution characteristics of the frequency, a load shedding model of the new energy power system is constructed, and by solving the load shedding model of the new energy power system, the flexible load power that the power system expects to shear includes:

[0207] According to the initial allocation results and combined with the spatial and temporal distribution characteristics of the frequency, an objective function and power constraint conditions are established to minimize the difference between the disturbance power initially allocated by the equivalent synchronous power source and the disturbance power allocated by the equivalent synchronous power source according to its inertia size.

[0208] According to the objective function and power constraints, the flexible load power that the power system expects to remove is solved.

[0209] In this optional embodiment, the expression of the objective function and power constraint condition for minimizing the difference between the disturbance power initially allocated by the equivalent synchronous power source and the disturbance power allocated by the equivalent synchronous power source according to its inertia size is:

[0210]

[0211] ΔP CLimin ≤ΔP CLi ≤ΔP CLimax ,i=1,2,…,n

[0212]

[0213] Where ΔP EGj represents the disturbance power initially distributed by the jth equivalent synchronous power source, ΔP Hj represents the disturbance power allocated to the jth equivalent synchronous power source according to its inertia size, m represents the number of equivalent synchronous power sources in the power system, ΔP CLimin and ΔP Climax They represent the minimum and maximum power of the flexible adjustment of the i-th node in the power system, n represents the number of nodes in the power system, ΔP CLi represents the flexible power adjustment of the ith node in the power system, P exp It indicates the flexible load power that the power system expects to remove.

[0214] 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.

[0215] 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.

[0216] 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.

[0217] 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.

[0218] 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).

[0219] 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 method for controlling low-frequency flexible load shedding of electric power, characterized in that: The method comprises the following steps: Obtain power data of the power system, and establish a power system node frequency model based on the power system node frequency generation mechanism; solve the node frequency based on the power system node frequency model to obtain the node frequency weight matrix information; The initial distribution of electromagnetic power is carried out based on the electrical distance between the power source and the location where the disturbance occurs. According to the initial distribution result and combined with the spatiotemporal distribution characteristics of the frequency, a load shedding model of the new energy power system is constructed. By solving the load shedding model of the new energy power system, the flexible load power expected to be shelved by the power system is obtained. According to the node frequency weight matrix information and the flexible load power that the power system expects to remove, the flexible load removal power is optimized and allocated, and the optimized allocation result is transmitted to the flexible load local device at each node; the flexible load local device at each node performs local power control on the flexible load according to the optimized allocation result.

2. The method for controlling low-frequency flexible load shedding of electric power according to claim 1, characterized in that: The expression of the power system node frequency model is: B EG (d EG -i)-P ELN (I+K EL f)-P CL =B0θ In the formula, B EG represents the diagonal array of susceptance in the equivalent power supply, δ EG represents the equivalent power source rotor angle column vector, θ represents the voltage phase angle vector of each node in the power system, P ELN represents the column vector of the rated active power absorbed by the equivalent load, I represents the unit vector, K EL represents the column vector of the active power regulation effect coefficient of the equivalent load, f represents the node frequency, P CL It represents the active power actually absorbed by the flexible load, and B0 represents the node susceptance matrix of the power system.

3. The method for controlling low-frequency flexible load shedding of electric power according to claim 2, characterized in that: Solving the node frequency based on the power system node frequency model to obtain the node frequency weight matrix information includes the following steps: The expression of the power system node frequency model is differentiated with respect to time, and the differentiation result is Laplace transformed to obtain the relationship function between the node frequency and the synchronous power supply speed; In a synchronous AC power system, the node frequency is solved based on the relationship between the rotor angle and the speed of the synchronous power supply and the relationship between the node voltage phase angle and the node frequency, and combined with the relationship function between the node frequency and the speed of the synchronous power supply, and the node frequency weight matrix information is determined based on the node frequency.

4. The method for controlling low-frequency flexible load shedding of electric power according to claim 1, characterized in that: The initial distribution of electromagnetic power based on the electrical distance between the power source and the location where the disturbance occurs comprises the following steps: Calculate the active output column vector of equivalent load based on the frequency response characteristics similar to grid-type renewable energy and load; According to the similar frequency response characteristics of grid-forming new energy and synchronous machine, the active output column vector of equivalent power supply is calculated; Based on the active output column vector of equivalent load, the active output column vector of equivalent power source and the power system node frequency model, the change of the instantaneous electromagnetic power of the synchronous power source is calculated, and the change of the instantaneous electromagnetic power of the synchronous power source is used as the initially allocated disturbance power.

5. The method for controlling low-frequency flexible load shedding of electric power according to claim 4, characterized in that: The calculation formula for the change in the instantaneous electromagnetic power of the synchronous power supply is: ΔP EG =W T ΔP CL Where ΔP EG Indicates the change in instantaneous electromagnetic power of the synchronous power supply, W T The transposed matrix of the weight matrix representing the node frequency, ΔP CL represents the flexible load disturbance vector.

6. The method for controlling low-frequency flexible load shedding of electric power according to claim 1, characterized in that: The method of constructing a load shedding model of a new energy power system based on the initial allocation result and combining the spatiotemporal distribution characteristics of the frequency, and solving the load shedding model of the new energy power system to obtain the flexible load power that the power system expects to shear includes the following steps: According to the initial allocation results and combined with the spatial and temporal distribution characteristics of the frequency, an objective function and power constraint conditions are established to minimize the difference between the disturbance power initially allocated by the equivalent synchronous power source and the disturbance power allocated by the equivalent synchronous power source according to its inertia size. According to the objective function and power constraints, the flexible load power that the power system expects to remove is solved.

7. The method for controlling low-frequency flexible load shedding of electric power according to claim 6, characterized in that: The expression of the objective function and power constraint condition for minimizing the difference between the disturbance power initially allocated by the equivalent synchronous power source and the disturbance power allocated by the equivalent synchronous power source according to its inertia size is: ΔP CLimin ≤ΔP CLi ≤ΔP CLimax ,i=1,2,…,n Where ΔP EGj represents the disturbance power initially distributed by the jth equivalent synchronous power source, ΔP Hj represents the disturbance power allocated to the jth equivalent synchronous power source according to its inertia size, m represents the number of equivalent synchronous power sources in the power system, ΔP CLimin and ΔP Climax They represent the minimum and maximum power of the flexible adjustment of the i-th node in the power system, n represents the number of nodes in the power system, ΔP CLi represents the flexible power adjustment of the ith node in the power system, P exp It indicates the flexible load power that the power system expects to remove.

8. A power low-frequency shedding flexible load control system, characterized in that: The system includes: The node frequency weight matrix information calculation module is used to obtain the power data of the power system and establish a power system node frequency model based on the power system node frequency generation mechanism; the node frequency is solved based on the power system node frequency model to obtain the node frequency weight matrix information; The flexible load power calculation module expected to be removed is used to perform the initial allocation of electromagnetic power based on the electrical distance between the power source and the location where the disturbance occurs. According to the initial allocation result and in combination with the spatiotemporal distribution characteristics of the frequency, a load removal model of the new energy power system is constructed. By solving the load removal model of the new energy power system, the flexible load power expected to be removed by the power system is obtained. The local power control module is used to optimize the allocation of flexible load removal power according to the node frequency weight matrix information and the flexible load power that the power system expects to remove, and transmit the optimized allocation result to the local device of the flexible load at each node; the local device of the flexible load at each node performs local power control on the flexible load according to the optimized allocation result.

9. The power low-frequency shedding flexible load control system according to claim 8, characterized in that: The expression of the power system node frequency model is: B EG (d EG -i)-P ELN (I+K EL f)-P CL =B0θ In the formula, B EG represents the diagonal array of susceptance in the equivalent power supply, δ EG represents the equivalent power source rotor angle column vector, θ represents the voltage phase angle vector of each node in the power system, P ELN represents the column vector of the rated active power absorbed by the equivalent load, I represents the unit vector, K EL represents the column vector of the active power regulation effect coefficient of the equivalent load, f represents the node frequency, P CL It represents the active power actually absorbed by the flexible load, and B0 represents the node susceptance matrix of the power system.

10. The electric power low-frequency shedding flexible load control system according to claim 9, characterized in that: The node frequency is solved based on the power system node frequency model to obtain the node frequency weight matrix information including: The expression of the power system node frequency model is differentiated with respect to time, and the differentiation result is Laplace transformed to obtain the relationship function between the node frequency and the synchronous power supply speed; In a synchronous AC power system, the node frequency is solved based on the relationship between the rotor angle and the speed of the synchronous power supply and the relationship between the node voltage phase angle and the node frequency, and combined with the relationship function between the node frequency and the speed of the synchronous power supply, and the node frequency weight matrix information is determined based on the node frequency.

11. The electric power low-frequency shedding flexible load control system according to claim 8, characterized in that: The initial distribution of electromagnetic power based on the electrical distance between the power source and the location where the disturbance occurs includes: Calculate the active output column vector of equivalent load based on the frequency response characteristics similar to grid-type renewable energy and load; According to the similar frequency response characteristics of grid-forming new energy and synchronous machine, the active output column vector of equivalent power supply is calculated; Based on the active output column vector of equivalent load, the active output column vector of equivalent power source and the power system node frequency model, the change of the instantaneous electromagnetic power of the synchronous power source is calculated, and the change of the instantaneous electromagnetic power of the synchronous power source is used as the initially allocated disturbance power.

12. The power low-frequency shedding flexible load control system according to claim 11, characterized in that: The calculation formula for the change in the instantaneous electromagnetic power of the synchronous power supply is: ΔP EG =W T ΔP CL Where ΔP EG Indicates the change in instantaneous electromagnetic power of the synchronous power supply, W T The transposed matrix of the weight matrix representing the node frequency, ΔP CL represents the flexible load disturbance vector.

13. The power low-frequency shedding flexible load control system according to claim 8, characterized in that: According to the initial allocation result and in combination with the spatiotemporal distribution characteristics of the frequency, a load shedding model of the new energy power system is constructed, and by solving the load shedding model of the new energy power system, the flexible load power expected to be shelved by the power system is obtained, including: According to the initial allocation results and combined with the spatial and temporal distribution characteristics of the frequency, an objective function and power constraint conditions are established to minimize the difference between the disturbance power initially allocated by the equivalent synchronous power source and the disturbance power allocated by the equivalent synchronous power source according to its inertia size. According to the objective function and power constraints, the flexible load power that the power system expects to remove is solved.

14. The electric power low-frequency shedding flexible load control system according to claim 13, characterized in that: The expression of the objective function and power constraint condition for minimizing the difference between the disturbance power initially allocated by the equivalent synchronous power source and the disturbance power allocated by the equivalent synchronous power source according to its inertia size is: ΔP CLimin ≤ΔP CLi ≤ΔP CLimax ,i=1,2,…,n Where ΔP EGj represents the disturbance power initially distributed by the jth equivalent synchronous power source, ΔP Hj represents the disturbance power allocated to the jth equivalent synchronous power source according to its inertia size, m represents the number of equivalent synchronous power sources in the power system, ΔP CLimin and ΔP Climax They represent the minimum and maximum power of the flexible adjustment of the i-th node in the power system, n represents the number of nodes in the power system, ΔP CLi represents the flexible power adjustment of the ith node in the power system, P exp It indicates the flexible load power that the power system expects to remove.

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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