Static voltage stability analysis method and device based on new energy grid connection

Abstract

The invention relates to the technical field of new energy power generation, and discloses a static voltage stability analysis method and device based on new energy grid connection, and the analysis method comprises the steps: obtaining the operation state of a new energy node in a power grid system; according to the operation state and the initial power flow equation of the network construction type node, a target power flow equation of the network construction type node is determined, and the network construction type node is a node adopting a network construction type control mode in the new energy nodes; and based on the target power flow equation, analyzing the stability of the static voltage of grid-connected power generation of the new energy node in the power grid system. Through the technical scheme of the invention, the problems of low accuracy and large analysis error of a static voltage stability calculation method in a novel power system in the prior art are solved, the accuracy of static voltage stability analysis based on new energy grid connection is improved, and the analysis error is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of renewable energy power generation, and in particular to a method and device for analyzing static voltage stability based on renewable energy grid connection. Background Art

[0002] The static voltage stability problem in new power systems is gradually shifting from being dominated by the traditional load side to being jointly dominated by the load side and the source side. Currently, several relatively mature static voltage stability analysis methods have been developed for traditional power systems. However, most traditional static voltage stability analysis methods treat renewable energy generation and traditional synchronous power sources as identical, treating them as power-voltage (PV) nodes with constant output. This fails to reflect the source-side impact of renewable energy's significant dynamic characteristics on the system's static voltage stability. As a result, related static voltage stability calculation methods in new power systems suffer from low accuracy and large analysis errors. Summary of the Invention

[0003] In view of this, the present invention provides a static voltage stability analysis method and device based on renewable energy grid connection to solve the problems of low accuracy and large analysis error in static voltage stability calculation methods in related technologies under new power systems.

[0004] In a first aspect, the present invention provides a static voltage stability analysis method based on new energy grid connection, the method comprising:

[0005] Obtain the operating status of new energy nodes in the power grid system;

[0006] Determine the target power flow equation of the grid-forming node according to the operating state of the grid-forming node and the initial power flow equation, wherein the grid-forming node is a node in the new energy node that adopts the grid-forming control mode;

[0007] Based on the target power flow equation, the stability of the static voltage of the new energy nodes connected to the grid system is analyzed.

[0008] Through this method, the target power flow equation of the grid-connected node of the new energy grid is obtained. Based on the target power flow equation, the stability of the static voltage of the grid-connected power generation of the new energy node in the power grid system is analyzed, which improves the accuracy of the static voltage stability analysis based on the new energy grid connection and reduces the analysis error.

[0009] In an optional embodiment, determining a target power flow equation of the meshing node according to the operating state of the meshing node and the initial power flow equation includes:

[0010] Identify the networking nodes that adopt the networking control mode among the new energy nodes;

[0011] According to the operation status of the network nodes, the initial power flow equation is updated to the first power flow equation;

[0012] According to the operating status of the meshing node and the steady-state current limiting control mode of the meshing node, the first power flow Jacobian matrix corresponding to the first power flow equation is updated to the second power flow Jacobian matrix, and the second power flow Jacobian matrix is ​​the Jacobian matrix corresponding to the target power flow equation.

[0013] In this embodiment, the second power flow Jacobian matrix is ​​calculated for the grid-connected nodes with current limiting control, which provides a key basis for the stability evaluation of the static voltage of the new energy nodes connected to the grid system for power generation.

[0014] In an optional implementation, identifying a meshing node that adopts a meshing control mode among new energy nodes includes:

[0015] Traverse the new energy nodes and check the control mode of the target node in the new energy nodes;

[0016] If the control mode is a meshing control mode, the target node is marked as a meshing node.

[0017] In this implementation, by traversing and marking grid-forming nodes, this method can accurately distinguish between different types of renewable energy nodes in the power grid (e.g., grid-forming and grid-following types), laying the foundation for subsequent specialized modeling and processing of grid-forming nodes. This ability to distinguish is a key prerequisite for improving the accuracy of renewable energy grid-connected system analysis and avoids errors caused by mixed model usage.

[0018] In an optional implementation, the initial power flow equation is updated to a first power flow equation according to the operating status of the meshing node, including:

[0019] The grid-forming node is set as a system regulation node, and the unbalanced power flow equation of the grid-forming node is constructed based on the voltage amplitude and active current of the grid-forming node in the topological network of the power grid system, the reactive power of the nodes connected to the grid-forming node, and the conductance, susceptance and phase angle difference between different nodes in the topological network in the operating state.

[0020] The unbalanced power flow equation and the initial power flow equation are combined into the first power flow equation.

[0021] In this implementation, the grid-forming nodes are configured as system regulation nodes (e.g., PV or balancing node variants). An unbalanced power flow equation is constructed based on their actual physical characteristics (voltage amplitude, active current, connected node reactive power, network admittance parameters, and phase angle difference). This unbalanced power flow equation is then integrated into the initial system power flow equation, forming a first power flow equation that better reflects the operating characteristics of the grid-forming inverter. This process significantly improves the physical realism and mathematical accuracy of the power flow calculation model at the new energy nodes, providing a more reliable input basis for stability analysis.

[0022] In an optional embodiment, according to the operating state of the meshing node and the steady-state current limiting control mode of the meshing node, the first power flow Jacobian matrix corresponding to the first power flow equation is updated to the second power flow Jacobian matrix, including:

[0023] Based on the solution of the first power flow equation, each element of the first power flow Jacobian matrix is ​​calculated. The solution includes the active power, reactive power, phase angle and voltage stability parameters of the grid-forming nodes.

[0024] Determine the real part of the principal characteristic root of the first power flow Jacobian matrix;

[0025] Determine the total current amplitude of the meshing node according to the active power, reactive power and voltage amplitude of the meshing node in the operating state;

[0026] If the total current amplitude is greater than or equal to the current limiting threshold, the first power flow equation is updated to the target power flow equation according to the real part of the main characteristic root of the first power flow Jacobian matrix and the steady-state current limiting control mode;

[0027] According to the partial derivatives of voltage amplitude and phase angle in the target power flow equation, the first power flow Jacobian matrix is ​​updated to obtain the second power flow Jacobian matrix.

[0028] In this implementation, the real part of the principal characteristic root of the first power flow Jacobian matrix is ​​calculated, providing a key indicator for subsequent determination of system stability margins and critical points. The total current amplitude of the meshed nodes is calculated in real time and compared with the current-limiting threshold to accurately identify whether the node has entered current-limited operation. During current-limited operation, the first power flow equation is updated to the target power flow equation, and the corresponding second power flow Jacobian matrix is ​​obtained, improving the Jacobian matrix's accuracy when approaching the limit or in the current-limiting state.

[0029] In an optional embodiment, the first power flow equation is updated to a target power flow equation according to the real part of the main characteristic root of the first power flow Jacobian matrix and the steady-state current limiting control mode, including:

[0030] If the steady-state current limiting control mode is the active power priority mode, the grid-forming node is set to the first type of node with constant active power and current output, and the current constraint equation is added to the first power flow equation to obtain the target power flow equation;

[0031] If the steady-state current limiting control mode is the reactive power priority mode, the grid-forming node is set to the second type of node without active power, and the active power equation is deleted from the first power flow equation and the current constraint equation is added to obtain the target power flow equation.

[0032] In this implementation, the voltage amplitude and phase angle partial derivatives are recalculated based on the updated target power flow equation (including current limiting constraints) to obtain a second power flow Jacobian matrix. This matrix incorporates the dynamic characteristics of the grid-forming nodes under current limiting (active power, reactive power, and current constraints), making stability analysis (such as eigenvalues ​​and sensitivity) based on this matrix more reliable and significantly reducing analysis errors caused by ignoring the effects of current limiting control.

[0033] In an optional embodiment, based on the target power flow equation, analyzing the stability of the static voltage of the new energy node connected to the grid for power generation in the power grid system includes:

[0034] Based on the main eigenvalues ​​of the second power flow Jacobian matrix and the load coefficient of the meshing node, the critical point at which the voltage of the meshing node is in an unstable state is determined. The critical point is continuously iterated until the voltage corresponding to the critical point converges to the target static voltage. When the real part of the main eigenvalue is 0, the target voltage value corresponding to the load coefficient of the meshing node is the static voltage at the critical point.

[0035] In this implementation, the second power flow Jacobian matrix and its principal eigenvalues, which incorporate precise meshing node models and the effects of current limiting control, combined with node load factors, can accurately determine the critical point of system voltage instability. Continuous iteration ensures that the critical point calculation converges to the true target static voltage (critical voltage). This method directly and effectively utilizes the eigenvalues ​​of the updated Jacobian matrix, significantly improving the accuracy of critical point location and providing a more reliable quantitative indicator for assessing system stability margins.

[0036] In an optional embodiment, determining a critical point at which the voltage of the meshing node is in an unstable state based on the main characteristic root of the second power flow Jacobian matrix and the load coefficient of the meshing node, and continuously iterating the critical point until the voltage corresponding to the critical point converges to the target static voltage includes:

[0037] According to the main characteristic root of the second power flow Jacobian matrix and the load coefficient of the network node, a target curve is generated in which the real part of the main characteristic root changes with the load coefficient;

[0038] According to the preset step size and iteration coefficient, the critical point where the voltage of the grid node is in an unstable state is detected point by point in the target curve. If the real part of the characteristic root corresponding to the target point in the target curve changes from a negative value to a positive value, the target point is regarded as the critical point, and the load factor corresponding to the target point is used as the static voltage limit threshold;

[0039] If the real part of the characteristic root corresponding to the target point is negative, the target point is iterated continuously until the voltage corresponding to the target point converges to the target static voltage, and the target static voltage is less than or equal to the static voltage limit threshold.

[0040] In this embodiment, a curve showing the change of the real part of the main characteristic root with the load factor is drawn to intuitively show the changing trend of the system stability with the increase of load. Using a preset step size and iteration coefficient, the critical point (the point where the real part of the characteristic root changes from negative to positive) is searched efficiently and accurately on the curve. The load factor corresponding to this point is the static voltage stability limit (collapse point). When the real part of the characteristic root is negative, the calculation point is continuously iterated and optimized to ensure that it eventually converges to the target static voltage value that meets the accuracy requirements (this value is less than or equal to the critical point voltage). This process ensures the numerical stability and reliability of the analysis results, especially the calculation accuracy when approaching the stability boundary.

[0041] In an optional embodiment, after continuously iterating the target point until the voltage corresponding to the target point converges to the target static voltage, the method further includes:

[0042] Visualize the target curve and the target points corresponding to the target static voltage;

[0043] The maximum load factor corresponding to the output target static voltage.

[0044] In this implementation, key analysis results (stability change curves, critical point locations, and the converged target static voltage point) are visualized, and the maximum safe load factor (or margin indicator) corresponding to the target static voltage is output. This greatly enhances the comprehensibility and practicality of the analysis results, enabling grid dispatchers and planners to intuitively grasp the system voltage stability boundary and safety margin, providing a clear and quantitative basis for operational decisions (such as preventive control and emergency control) and planning optimization.

[0045] In a second aspect, the present invention provides a static voltage stability analysis device based on renewable energy grid-connected power generation, the device comprising:

[0046] An acquisition module is used to obtain the operating status of new energy nodes in the power grid system;

[0047] a determination module for determining a target power flow equation of the grid-forming node based on the operating state of the grid-forming node and the initial power flow equation, wherein the target power flow equation is used to analyze the stability of the static voltage of the new energy node connected to the grid for power generation in the power grid system, wherein the grid-forming node is a node in the new energy node that adopts the grid-forming control mode;

[0048] The analysis module is used to analyze the stability of the static voltage of the grid-connected power generation of new energy nodes in the power grid system based on the target power flow equation. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0050] Figure 1 is a flow chart of a static voltage stability analysis method based on new energy grid connection according to an embodiment of the present invention;

[0051] Figure 2 This is a flow chart of another static voltage stability analysis method based on new energy grid connection according to an embodiment of the present invention;

[0052] Figure 3 Schematic diagram of a flow chart of a method for visualizing static voltage stability analysis results based on new energy grid connection according to an embodiment of the present invention;

[0053] Figure 4 Schematic diagram of a flow chart of another static voltage stability analysis method based on new energy grid connection according to an embodiment of the present invention;

[0054] Figure 5 This is a block diagram of a grid-type new energy voltage loop control according to an embodiment of the present invention;

[0055] Figure 6 2 is a structural block diagram of a static voltage stability analysis device based on renewable energy grid-connected power generation according to an embodiment of the present invention;

[0056] Figure 7 Schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0057] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0058] The technical solutions in the embodiments of the present invention can be applied to the following technical scenarios or fields: In the design and optimization scenario of a high proportion of grid-connected new energy systems, it can be used for large-scale wind / photovoltaic power station grid-connected planning and offshore wind power cluster access system design, by accurately analyzing the static voltage stability boundary of the grid-connected new energy nodes, optimizing the capacity configuration and access scheme of the new energy station, and avoiding the overload risk caused by model simplification. For example, when a wind and solar cluster is connected to a weak power grid through a grid-connected inverter, its voltage support capability and stability limit are accurately evaluated. In the real-time operation and safety control scenario of a new power system, it can be used for grid dispatch decision support, online calculation of the static voltage stability margin of the new energy node, providing key parameters (such as the maximum safe load factor) for dispatchers, and formulating preventive control strategies. It can also be used for current limiting control mode switching warning. When the current of the grid-connected node approaches the current limiting threshold, the voltage instability risk is dynamically predicted based on the second flow Jacobian matrix, triggering control mode switching or load reduction protection. In the controller verification scenario of grid-type new energy equipment (such as virtual synchronous machines), it can be used in the hardware test of grid-type inverters to verify the actual impact of the control strategy on the system voltage stability through the Jacobian matrix and critical point data generated by this method. For example, the performance of the virtual synchronous machine voltage regulation control algorithm in the current limiting mode is evaluated. In the power market auxiliary service pricing and capacity planning scenario, it can be used for data analysis support, quantifying the contribution of new energy nodes to the static voltage stability of the system (such as through Jacobian matrix sensitivity analysis), and providing a technical basis for the pricing mechanism of new energy participating in voltage regulation auxiliary services. The above application scenarios are only examples of the use scenarios of this technical solution, and this embodiment does not limit the application scenarios of this technical solution.

[0059] An embodiment of the present invention provides a static voltage stability analysis method based on the connection of new energy to the grid. By analyzing the operating status of the new energy node and the power flow equation, the Jacobian matrix corresponding to the power flow equation is determined, thereby improving the accuracy of the static voltage stability analysis based on the connection of new energy to the grid and reducing the analysis error.

[0060] According to an embodiment of the present invention, an embodiment of a static voltage stability analysis method based on the grid connection of new energy is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0061] In this embodiment, a static voltage stability analysis method based on renewable energy grid connection is provided, which can be used for various computing devices, such as personal computers, cloud servers, Figure 1 FIG. 1 is a flow chart of a static voltage stability analysis method based on new energy grid connection according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0062] Step S101: Acquire the operating status of the new energy node in the power grid system.

[0063] In this embodiment, a new energy node refers to a connection point in the power system where new energy power generation equipment (such as a wind farm, photovoltaic power station, or energy storage power station) is connected. This connection point has a voltage amplitude and phase angle in the grid topology. The operating status includes grid topology parameters, the grid connection location of the new energy node, the control mode, the steady-state current limit value, the voltage, current, load, conductance, susceptance, and phase angle of each node. Obtaining the operating status of the new energy node from the power grid system provides a data source for the static voltage stability analysis of the new energy grid connection.

[0064] Step S102 : determining a target power flow equation of the meshing node according to the operating state of the meshing node and the initial power flow equation, wherein the meshing node is a node in the new energy node that adopts a meshing control mode.

[0065] In this embodiment, the grid-forming node refers to a node in the new energy node that adopts the grid-forming control mode. The initial power flow equation refers to a set of nonlinear algebraic equations consisting of the default node power balance equations in the power grid system, which reflects the mathematical relationship between the active power P, reactive power Q, voltage amplitude V, and phase angle θ of each node when the power system is in steady state operation. The target power flow equation refers to the power flow equation satisfied by the new energy node when the static voltage stability error of the new energy grid is minimized. According to the operating state of the grid-forming node and the initial power flow equation, the target power flow equation is obtained by adding the reactive power imbalance power flow equation.

[0066] Step S103 : analyzing the stability of the static voltage of the new energy node connected to the grid for power generation based on the target power flow equation.

[0067] In this embodiment, the corresponding Jacobian matrix is ​​calculated based on the target power flow equation. The value of the real part of the main characteristic root of the Jacobian matrix can reflect the stability of the static voltage of the new energy node connected to the grid for power generation in the power grid system. If the real part of the main characteristic root is negative, it means that the static voltage is in a stable state; if the real part of the main characteristic root is 0, it means that the static voltage is at the critical point of switching from stable to unstable; if the real part of the main characteristic root is positive, it means that the static voltage is in an unstable state.

[0068] The method of this embodiment improves the accuracy of static voltage stability analysis based on new energy grid connection and reduces analysis errors.

[0069] In this embodiment, a static voltage stability analysis method based on renewable energy grid connection is provided, which can be used for various computing devices, such as personal computers, cloud servers, etc. Figure 2 FIG. 1 is a flow chart of another static voltage stability analysis method based on new energy grid connection according to an embodiment of the present invention. Figure 2 As shown, the process includes the following steps:

[0070] Step S201: Acquire the operating status of the new energy node in the power grid system.

[0071] For details, please see Figure 1 Step S101 of the illustrated embodiment will not be described in detail here.

[0072] Step S202 : determining a target power flow equation of the meshing node according to the operating state of the meshing node and the initial power flow equation, wherein the meshing node is a node in the new energy node that adopts a meshing control mode.

[0073] Specifically, the above step S202 includes:

[0074] Step S2021: Identify the meshing nodes that adopt the meshing control mode among the new energy nodes.

[0075] All grid-forming nodes adopting a grid-forming control mode are identified from all new energy nodes in the power grid system.

[0076] Step S2022: updating the initial power flow equation to a first power flow equation according to the operation status of the meshing node.

[0077] In this embodiment, the first power flow equation refers to a power flow equation that treats the grid-forming node as a power quadrature (PQ) node and adds the associated reactive power imbalance. Based on the operating state of the grid-forming node, the reactive power imbalance is added to the initial power flow equation to obtain the first power flow equation.

[0078] Step S2023: According to the operation state of the meshing node and the steady-state current limiting control mode of the meshing node, the first power flow Jacobian matrix corresponding to the first power flow equation is updated to the second power flow Jacobian matrix, and the second power flow Jacobian matrix is ​​the Jacobian matrix corresponding to the target power flow equation.

[0079] In this embodiment, the first power flow Jacobian matrix refers to the partial derivative matrix after the linearization of the first power flow equation. Similar to the first power flow Jacobian matrix, the second power flow Jacobian matrix refers to the Jacobian matrix corresponding to the target power flow equation. According to the operating status of the meshing node, the first power flow Jacobian matrix under the steady-state current limiting control mode of the meshing node is updated to the second power flow Jacobian matrix. For example, the elements associated with the meshing node in the first power flow Jacobian matrix are corrected, the dynamic characteristics of the equipment of the meshing node are fully considered, and the coupling terms of active power and reactive power to voltage and phase angle are added.

[0080] Step S203 : Analyze the stability of the static voltage of the new energy node connected to the grid for power generation based on the target power flow equation.

[0081] For details, please see Figure 1 Step S103 of the illustrated embodiment will not be described in detail here.

[0082] In some optional implementations, the above step S2021 includes:

[0083] Step a1: traverse the new energy nodes and check the control mode of the target node in the new energy nodes.

[0084] In this embodiment, the target node refers to a node currently being processed when traversing all new energy nodes in the power grid system. The new energy nodes are traversed and the control modes of the target nodes are checked one by one.

[0085] Step a2: If the control mode is a meshing control mode, the target node is marked as a meshing node.

[0086] In this embodiment, the grid-forming control mode refers to a core control strategy for renewable energy power generation equipment (such as photovoltaic inverters and wind power converters) that autonomously builds grid voltage and frequency. Its essence is to simulate the physical characteristics of traditional synchronous generators, transforming renewable energy equipment from "followers" to "supporters," becoming the voltage and frequency source for the new power system. For target nodes whose control mode is the grid-forming control mode, the target node is marked as a grid-forming node.

[0087] Through this implementation, network-forming nodes are screened out from new energy nodes, and node objects to be processed are obtained.

[0088] In some optional implementations, the above step S2022 includes:

[0089] Step b1, setting the meshing node as a system regulation node, and constructing the unbalanced power flow equation of the meshing node based on the voltage amplitude and active current of the meshing node in the topological network of the power grid system, the reactive power of the nodes connected to the meshing node, and the conductance, susceptance and phase angle difference between different nodes in the topological network in the operating state.

[0090] In this embodiment, the system regulation type node refers to a meshing type node that simulates the characteristics of a synchronous machine. Conductance refers to the inverse of the line resistance in the power grid system, reflecting the active power loss. Susceptance refers to the capacity of the line in the power grid system to accommodate alternating current, reflecting the reactive power exchange. The unbalanced power flow equation refers to a temporary equation that describes the relationship between the power and voltage of the meshing type node. The meshing type node is set as a system regulation type node, such as a controlled PQ node. The unbalanced power flow equation of the meshing type node is constructed based on the voltage amplitude and active current of the meshing type node in the topological network of the power grid system, the reactive power of the nodes connected to the meshing type node, and the conductance, susceptance and phase angle difference between different nodes in the topological network in the operating state.

[0091] Step b2: merging the unbalanced power flow equation and the initial power flow equation into a first power flow equation.

[0092] In this embodiment, the unbalanced power flow equation and the initial power flow equation are combined to obtain the first power flow equation. In one example of this embodiment, the first power flow equation is as follows:

[0093]

[0094] Among them, U i is the voltage amplitude of the grid-forming new energy node, i d is the active current of the grid-connected new energy, i q is the active current of the grid-connected new energy, P Li is the active load of the nodes connected to the network-type new energy, Q Li is the reactive load of the nodes connected to the grid-type new energy, U k is the voltage amplitude of the kth node in the system, G ik is the conductance between the i-th node and the k-th node in the system, B ik is the susceptance between the i-th node and the k-th node in the system, θ ik is the phase angle difference between the i-th node and the k-th node in the system.

[0095] Through this implementation, a first power flow equation that is more in line with the operating characteristics of the grid-type inverter is constructed, thereby improving the authenticity and accuracy of the power flow calculation model at the new energy node.

[0096] In some optional implementations, step S2023 includes:

[0097] Step c1, calculating each element of the first power flow Jacobian matrix according to the solution of the first power flow equation, wherein the solution includes the active power, reactive power, phase angle and voltage stability parameter of the grid-forming node.

[0098] In this embodiment, the variables obtained after solving the first power flow equation are the solution values ​​of the first power flow equation, including the active power, reactive power, phase angle, and voltage stability parameters of the grid-forming node. Based on the solution values ​​of the first power flow equation, each element in the first power flow Jacobian matrix is ​​calculated to complete the correction of the first power flow Jacobian matrix. In some examples of this embodiment, the following calculation method can be used to calculate the correction term:

[0099]

[0100] Among them, P Gi is the active power output of the network-type new energy node, k pac is the proportional parameter of the grid-type new energy voltage loop, Q Gi is the reactive power output of the grid-type new energy node, θ i is the phase angle of the network-forming new energy node.

[0101] Step c2: determine the real part of the principal characteristic root of the first power flow Jacobian matrix.

[0102] In this embodiment, the eigenvalues ​​are calculated for the first power flow Jacobian matrix, and the largest real part of the eigenvalues ​​is used as the real part of the main eigenroot, which is used as the eigenroot state under the current load factor of the meshing node.

[0103] Step c3: determining the total current amplitude of the meshing node according to the active power, reactive power and voltage amplitude of the meshing node in the operating state.

[0104] In this embodiment, active power refers to the actual energy delivered by the meshing node to the power grid, which is used to drive the load to do work. Reactive power refers to the exchange power used by the meshing node to maintain the grid voltage. The voltage amplitude refers to the line voltage amplitude of the grid-connected point of the meshing node. The total current amplitude refers to the comprehensive effective value of the output current of the meshing node, which includes active and reactive components and can be used as the core criterion for determining whether the node triggers current limiting protection. Based on the active power, reactive power and voltage amplitude of the meshing node in the operating state of the power grid system, the total current amplitude of the meshing node can be calculated.

[0105] In one example of this embodiment, the total current amplitude I is determined by the following formula: total .

[0106]

[0107] Among them, the total current amplitude I total Active component I d =P Gi / V i , reactive component I q =Q Gi / V i , the active power P of the network node Gi , reactive power Q Gi and voltage amplitude V i .

[0108] Step c4: if the total current amplitude is greater than or equal to the current limiting threshold, the first power flow equation is updated to a target power flow equation according to the real part of the main characteristic root of the first power flow Jacobian matrix and the steady-state current limiting control mode.

[0109] In this embodiment, the current limiting threshold is used to measure the magnitude of the total current threshold. If the total current amplitude is greater than or equal to the current limiting threshold, it indicates that the meshing node has entered the current limiting mode. Based on the real part of the principal eigenvalue of the first power flow Jacobian matrix and different steady-state current limiting control modes, the first power flow equation is updated to the target power flow equation according to the node type of the meshing node.

[0110] In one example of this embodiment, if I total max , where I max If the set current limit amplitude is not reached, the PV node model is maintained during the process of drawing the steady-state nose curve. Otherwise, the current limit mode is triggered.

[0111] Step c5: Update the first power flow Jacobian matrix according to the partial derivatives of the voltage amplitude and the phase angle in the target power flow equation to obtain the second power flow Jacobian matrix.

[0112] In this embodiment, as in the method of correcting the first power flow Jacobian matrix in step c1, the first power flow Jacobian matrix is ​​corrected according to the partial derivatives of the voltage amplitude and phase angle in the target power flow equation to obtain the second power flow Jacobian matrix.

[0113] Through this embodiment, in the current limiting mode, the first power flow equation is updated to the target power flow equation, and the second power flow Jacobian matrix corresponding to the target power flow equation is obtained, thereby improving the representation accuracy of the Jacobian matrix in the current limiting mode.

[0114] In some optional implementations, the above step c4 includes:

[0115] ​Step d1: If the steady-state current limiting control mode is the active power priority mode, the meshing node is set to a first-class node with constant active power and current output, and a current constraint equation is added to the first power flow equation to obtain a target power flow equation.

[0116] In this embodiment, a first-class node refers to a meshing node with constant active power output and constant current output. The current constraint equation is an equation that ensures that the current satisfies predefined conditions. If the steady-state current limiting control mode is active power priority mode, the meshing node is set to the first-class node type. That is, the node's external characteristics are reconstructed to that of a first-class node. Simultaneously, the active power equation is retained on top of the first power flow equation, and a current constraint equation is added to obtain the target power flow equation.

[0117] In one example of this embodiment, the current constraint equation is as follows:

[0118]

[0119] Among them, ΔI i is the current unbalance of the grid-type new energy node power flow equation, I Li is the load current of the node, I ik is the current flowing from node i to node k.

[0120] Step d2: If the steady-state current limiting control mode is the reactive power priority mode, the grid-forming node is set to a second type of node without active power, and the active power equation is deleted from the first power flow equation and the current constraint equation is added to obtain the target power flow equation.

[0121] In this embodiment, the second type of node refers to a meshing node that does not include active power. If the steady-state current limiting control mode is reactive power priority mode, the meshing node is set to the second type of node. The active power equation is deleted from the first power flow equation, and the current constraint equation is added to obtain the target power flow equation.

[0122] Through this embodiment, according to the dynamic characteristics of the meshing nodes in the current limiting state, the stability analysis result of the second power flow Jacobian matrix is ​​made more reliable, and the error of the stability analysis in the current limiting mode is improved.

[0123] In some optional implementations, the above step S203 includes:

[0124] Step e1: Determine the critical point at which the voltage of the meshing node is in an unstable state based on the main characteristic root of the second power flow Jacobian matrix and the load coefficient of the meshing node, and continuously iterate the critical point until the voltage corresponding to the critical point converges to the target static voltage. When the real part of the main characteristic root is 0, the target voltage value corresponding to the load coefficient of the meshing node is the static voltage of the critical point.

[0125] In this embodiment, the load factor of a meshing node refers to a proportional factor that measures the current load level of the node relative to the reference load. The target static voltage refers to the steady-state voltage of the meshing node before it approaches an unstable state. Based on the principal eigenvalue of the second power flow Jacobian matrix and the load factor of the meshing node, the critical point at which the voltage of the meshing node is unstable can be determined, and the critical point is continuously iterated until the voltage corresponding to the critical point converges to the target static voltage. Optionally, when the real part of the principal eigenvalue is 0, the target voltage value corresponding to the load factor of the meshing node is the static voltage at the critical point.

[0126] Through this implementation, the position of the critical point is continuously iterated, providing a more accurate critical point position for the stability analysis of the static voltage in the grid-connected new energy nodes, and gradually reducing the stability analysis error.

[0127] In some optional implementations, the above step e1 includes:

[0128] Step f1: generating a target curve in which the real part of the main characteristic root varies with the load coefficient according to the main characteristic root of the second power flow Jacobian matrix and the load coefficient of the meshing node.

[0129] In this embodiment, the voltage amplitude corresponding to the real part of the principal characteristic root of the second power flow Jacobian matrix is ​​plotted on the vertical axis, and the load factor of the meshing node is plotted on the horizontal axis. A target curve is generated, where the real part of the principal characteristic root varies with the load factor. Preferably, the target curve is a PV curve.

[0130] In step f2, based on the preset step size and iteration coefficient, the critical point where the voltage of the grid-type node is in an unstable state is detected point by point in the target curve. If the real part of the characteristic root corresponding to the target point in the target curve changes from a negative value to a positive value, the target point is used as the critical point, and the load factor corresponding to the target point is used as the static voltage limit threshold.

[0131] In this embodiment, the preset step size is the length that can be advanced in each cycle when searching for the target curve. The longer the preset step size, the faster the iteration of the target curve and the fewer target points that can be iterated. Conversely, the slower the iteration, the more target points that can be iterated and the more accurate the positioning of the critical point. The iteration coefficient is a weight parameter of the step size, which is used to adjust the iteration accuracy and speed by adaptive step size. According to the preset compensation and iteration coefficient, the critical point where the voltage of the grid-type node is in an unstable state is detected point by point in the target curve. If the real part of the characteristic root corresponding to the target point in the target curve is detected to change from a negative value to a positive value, it means that this target point is a critical state where the voltage changes from a stable state to an unstable state. The target point is set as the critical point, and the load coefficient corresponding to the target point is used as the static voltage limit threshold, indicating the maximum value of the stable state that the static voltage can reach.

[0132] Optionally, a tangential-vertical correction method can be used to advance the tangential prediction along the PV curve, using an adaptive step size (e.g., step coefficient) and increasing the load factor according to the sensitivity of the current power flow Jacobian matrix. Vertical or horizontal correction can then be used to correct the predicted points using the Newton-Raphson method to ensure that the critical point converges to the target static voltage of the new steady-state. If the horizontal increment is greater than the vertical increment, vertical correction is used; if the horizontal increment is less than the vertical increment, horizontal correction is used.

[0133] Step f3: If the real part of the characteristic root corresponding to the target point is a negative value, the target point is iterated continuously until the voltage corresponding to the target point converges to the target static voltage, and the target static voltage is less than or equal to the static voltage limit threshold.

[0134] In this embodiment, if the real part of the characteristic root corresponding to the target point on the target curve is negative, it indicates that the voltage of the meshed node is stable. The target point can be iterated until the voltage corresponding to the target point converges to the target static voltage. The target static voltage is less than or equal to the static voltage limit threshold, indicating a voltage that is stable at or before the critical point.

[0135] This implementation proposes a real-time eigenvalue tracking algorithm. By continuously monitoring the real part of the dominant eigenvalue root of the Jacobian matrix, a stability criterion that considers the dynamic characteristics of the equipment is established, replacing the traditional PV curve inflection point method and improving sensitivity. A hybrid tangential-vertical correction solution is proposed. Combining the rapidity of tangential prediction with the robustness of vertical correction, it addresses the power flow convergence challenge in power grids with a high proportion of renewable energy.

[0136] In this embodiment, a static voltage stability analysis method based on new energy grid connection is provided. Figure 3 FIG. 1 is a flow chart of a method for visualizing static voltage stability analysis results based on new energy grid connection according to an embodiment of the present invention. Figure 3 As shown, in some optional embodiments, the method includes the following steps:

[0137] Step S301 : generating a target curve in which the real part of the main characteristic root varies with the load coefficient according to the main characteristic root of the second power flow Jacobian matrix and the load coefficient of the meshing node.

[0138] Please refer to step f1 above for details and will not be repeated here.

[0139] In step S302, based on a preset step size and iteration coefficient, the critical point where the voltage of the meshed node is in an unstable state is detected point by point in the target curve. If the real part of the characteristic root corresponding to the target point in the target curve changes from a negative value to a positive value, the target point is used as the critical point, and the load factor corresponding to the target point is used as the static voltage limit threshold.

[0140] Please refer to step f2 above for details and will not be repeated here.

[0141] Step S303 : If the real part of the characteristic root corresponding to the target point is a negative value, the target point is iterated continuously until the voltage corresponding to the target point converges to the target static voltage, and the target static voltage is less than or equal to the static voltage limit threshold.

[0142] Please refer to step f3 above for details and will not be repeated here.

[0143] Step S304 : Visualizing the target curve and the target point corresponding to the target static voltage.

[0144] In this embodiment, after obtaining the target static voltage based on the voltage stability analysis of the new energy grid connection, the target curve and the target points corresponding to the target static voltage are visualized and displayed through the user interface, intuitively providing the stability boundary of the power grid system.

[0145] Step S305: outputting the maximum load factor corresponding to the target static voltage.

[0146] In this embodiment, while visualizing the target curve and the target point, the maximum load factor corresponding to the target static voltage is output.

[0147] Through this embodiment, the comprehensibility and practicality of the analysis results are enhanced.

[0148] In this embodiment, a static voltage stability analysis method based on new energy grid connection is provided. Figure 4 FIG. 1 is a flow chart of another static voltage stability analysis method based on new energy grid connection according to an embodiment of the present invention. Figure 4As shown, the grid topology and renewable energy parameters are input, and the power flow calculation is initialized. Constant-terminal voltage control nodes are treated as PV nodes. All system nodes are traversed to identify grid-type control. The current node is determined to be a grid-type control renewable energy node. If so, the node's external characteristics are reconstructed, the node power flow equation is reformulated, and a voltage loop correction is added. The power flow Jacobian matrix and partial derivative terms are updated. If the current node is not a grid-type control renewable energy node, the traditional PQ or PV node model is maintained, and the power flow Jacobian matrix and partial derivative terms are updated. The load factor is increased using an adaptive step size, and tangential prediction is performed. The horizontal increment is determined to be greater than the vertical increment. If so, the Newton-Raphson method is used for vertical correction, and the total current amplitude of the grid-type node is calculated. If the horizontal increment is less than or equal to the vertical increment, the total current amplitude of the grid-type node is calculated. Furthermore, the system determines whether the total current amplitude reaches the steady-state limiting current. If so, the node type is switched based on the current limiting control mode. The power flow Jacobian matrix is ​​reconstructed, the partial derivatives are updated, and the real part of the dominant characteristic root of the power flow Jacobian matrix is ​​calculated. If the total current amplitude does not reach the total current amplitude, the current node model is maintained, and the real part of the dominant characteristic root is calculated. A determination is made as to whether the real part of the dominant characteristic root crosses zero. If not, the load factor is increased using an adaptive step size to perform tangential prediction. If so, the critical point load factor is recorded, and the PV curve and the location of the critical point of static voltage collapse are output. This provides a critical point for static voltage stability analysis of renewable energy nodes connected to the grid. A negative voltage at the critical point indicates stable static voltage, while a positive voltage at the critical point indicates unstable static voltage. Through continuous iterations, the point where the negative value transitions to a positive value is determined, resulting in the target critical point that determines stability. This improves the accuracy of static voltage stability analysis based on renewable energy grid integration and reduces analysis errors.

[0149] Figure 5 This is a block diagram of a grid-type new energy voltage loop control in an embodiment of the present invention. Figure 5 As shown, the d-axis component U of the actual voltage of the power grid is collected. d and the q-axis component U q , will U d and d-axis reference voltage U dref (usually set to the rated value) and compare to generate the d-axis error ΔU d =U dref -U d . Will U q With q-axis reference voltage U qref (Always set to 0) Compare and generate the q-axis error ΔU q =U qref -U q .

[0150] The two independent PI controllers process the errors respectively as follows, thus achieving PI regulation:

[0151] i dref =(K pac ΔU q +K iac ∫ΔU d d t )+x1

[0152] i qref =(K pac ΔU q +K iac ∫ΔU d d t )+x2

[0153] Among them, K pac K is the proportional gain, used to quickly respond to voltage fluctuations. iac / s is the integral gain, which accumulates the error through the state variables x1 and x2 to eliminate the steady-state deviation. dref and i qref It is sent to the inner loop current controller to drive the inverter to output the d-axis current i d To adjust the active power to maintain frequency stability, and at the same time drive the inverter to output q-axis current i q To adjust the reactive power to support the voltage amplitude. d and i q The total current amplitude can be calculated, thereby triggering the steady-state current limiting mode switching and the dynamic update of the Jacobian matrix, ultimately ensuring the accuracy of the voltage stability analysis.

[0154] This embodiment also provides a static voltage stability analysis device based on renewable energy grid-connected power generation. This device is used to implement the above-mentioned embodiments and preferred embodiments, and the details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation using hardware, or a combination of software and hardware, is also possible and contemplated.

[0155] This embodiment provides a static voltage stability analysis device based on renewable energy grid-connected power generation. Figure 6 Shown, including:

[0156] Acquisition module 601, used to obtain the operating status of the new energy node in the power grid system;

[0157] Determination module 602, configured to determine a target power flow equation for the grid-forming node based on the operating state of the grid-forming node and the initial power flow equation, wherein the target power flow equation is used to analyze the stability of the static voltage of the new energy node during grid-connected power generation in the power grid system, wherein the grid-forming node is a node in the new energy node that adopts the grid-forming control mode;

[0158] The analysis module 603 is used to analyze the stability of the static voltage of the new energy node connected to the grid for power generation based on the target power flow equation.

[0159] In some optional implementations, the determining module 602 includes:

[0160] An identification unit, used to identify a meshing node that adopts a meshing control mode among new energy nodes;

[0161] An equation updating unit, configured to update the initial power flow equation to a first power flow equation according to the operating status of the network-forming node;

[0162] The matrix updating unit is used to update the first power flow Jacobian matrix corresponding to the first power flow equation to the second power flow Jacobian matrix according to the operating status of the meshing node and the steady-state current limiting control mode of the meshing node. The second power flow Jacobian matrix is ​​the Jacobian matrix corresponding to the target power flow equation.

[0163] In some optional embodiments, the identification unit includes:

[0164] A checking subunit, used for traversing the new energy nodes and checking the control mode of the target node in the new energy nodes;

[0165] The marking unit is used to mark the target node as a meshing node if the control mode is a meshing control mode.

[0166] In some optional implementations, the equation updating unit includes:

[0167] A construction subunit is used to set the meshing node as a system regulation node, and to construct an unbalanced power flow equation for the meshing node based on the voltage amplitude and active current of the meshing node in the topological network of the power grid system, the reactive power of the nodes connected to the meshing node, and the conductance, susceptance, and phase angle difference between different nodes in the topological network in the operating state;

[0168] The merging subunit is used to merge the unbalanced power flow equation and the initial power flow equation into the first power flow equation.

[0169] In some optional implementations, the matrix updating unit includes:

[0170] A calculation subunit, configured to calculate each element of the first power flow Jacobian matrix according to the solution of the first power flow equation, wherein the solution includes active power, reactive power, phase angle, and voltage stability parameter of the grid-forming node;

[0171] A first determining subunit is used to determine the real part of the principal characteristic root of the first power flow Jacobian matrix;

[0172] A second determining subunit is used to determine the total current amplitude of the meshing node according to the active power, reactive power and voltage amplitude of the meshing node in the operating state;

[0173] an equation updating subunit, configured to update the first power flow equation to a target power flow equation according to the real part of the principal characteristic root of the first power flow Jacobian matrix and the steady-state current limiting control mode if the total current amplitude is greater than or equal to the current limiting threshold;

[0174] The matrix updating subunit is used to update the first power flow Jacobian matrix according to the partial derivatives of the voltage amplitude and the phase angle in the target power flow equation to obtain the second power flow Jacobian matrix.

[0175] In some optional implementations, the equation updating subunit is configured to:

[0176] If the steady-state current limiting control mode is the active power priority mode, the grid-forming node is set to the first type of node with constant active power and current output, and the current constraint equation is added to the first power flow equation to obtain the target power flow equation;

[0177] If the steady-state current limiting control mode is the reactive power priority mode, the grid-forming node is set to the second type of node without active power, and the active power equation is deleted from the first power flow equation and the current constraint equation is added to obtain the target power flow equation.

[0178] In some optional implementations, the analysis module 603 includes:

[0179] The iterative unit is used to determine the critical point at which the voltage of the meshing node is in an unstable state according to the main characteristic root of the second power flow Jacobian matrix and the load coefficient of the meshing node, and continuously iterate the critical point until the voltage corresponding to the critical point converges to the target static voltage, wherein when the real part of the main characteristic root is 0, the target voltage value corresponding to the load coefficient of the meshing node is the static voltage of the critical point.

[0180] In some optional embodiments, the iteration unit includes:

[0181] A generating subunit, for generating a target curve in which the real part of the main characteristic root varies with the load coefficient according to the main characteristic root of the second power flow Jacobian matrix and the load coefficient of the network-type node;

[0182] The detection subunit is used to detect the critical point where the voltage of the grid-type node is in an unstable state point by point in the target curve according to a preset step size and iteration coefficient. If the real part of the characteristic root corresponding to the target point in the target curve changes from a negative value to a positive value, the target point is regarded as the critical point, and the load factor corresponding to the target point is used as the static voltage limit threshold;

[0183] The iterator unit is used to continuously iterate the target point until the voltage corresponding to the target point converges to the target static voltage if the real part of the characteristic root corresponding to the target point is negative, and the target static voltage is less than or equal to the static voltage limit threshold.

[0184] In some optional implementations, the iterator unit is further configured to:

[0185] Visualize the target curve and the target points corresponding to the target static voltage;

[0186] The maximum load factor corresponding to the output target static voltage.

[0187] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0188] The static voltage stability analysis device based on renewable energy grid-connected power generation in this embodiment is presented in the form of a functional unit, where the unit refers to an application-specific integrated circuit (ASIC) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0189] The embodiment of the present invention also provides a computer device having the above Figure 6 The static voltage stability analysis device based on new energy grid-connected power generation is shown.

[0190] See also Figure 7 , Figure 7 is a structural diagram of a computer device provided by an optional embodiment of the present invention, such as Figure 7As shown, the computer device includes: one or more processors 10, memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components utilize different buses to communicate with each other and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in the memory or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Equally, multiple computer devices can be connected, and each device provides part of the necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 7 A processor 10 is taken as an example.

[0191] The processor 10 may be a central processing unit, a network processor, or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic, or any combination thereof.

[0192] The memory 20 stores instructions that can be executed by at least one processor 10, so that the at least one processor 10 executes the method shown in the above embodiment.

[0193] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created based on the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0194] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0195] The computer device further includes an input device 30 and an output device 40. The processor 10, the memory 20, the input device 30 and the output device 40 may be connected via a bus or other means. Figure 7 The bus connection is taken as an example.

[0196] The input device 30 can receive input digital or character information and generate key signal input related to user settings and function control of the computer device, such as a touch screen, a keypad, a mouse, a trackpad, a touch pad, an indicator stick, one or more mouse buttons, a trackball, a joystick, etc. The output device 40 can include a display device, an auxiliary lighting device (e.g., an LED), and a tactile feedback device (e.g., a vibration motor). The above-mentioned display device includes but is not limited to a liquid crystal display, a light emitting diode, a display, and a plasma display. In some optional embodiments, the display device can be a touch screen.

[0197] The embodiment of the present invention also provides a computer-readable storage medium. The above-mentioned method according to the embodiment of the present invention can be implemented in hardware, firmware, or implemented as a computer code that can be recorded in a storage medium, or implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memory. It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor or hardware, the method shown in the above embodiment is implemented.

[0198] A portion of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the form in which the computer program instruction exists in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc. Accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium that can be accessed by the computer.

[0199] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A static voltage stability analysis method based on renewable energy grid-connected power generation, characterized in that: The method comprises: Obtain the operating status of new energy nodes in the power grid system; Determining a target power flow equation of the meshing node according to an operating state of the meshing node and an initial power flow equation, wherein the meshing node is a node in the new energy node that adopts a meshing control mode; Based on the target power flow equation, the stability of the static voltage of the new energy node in the power grid system during grid-connected power generation is analyzed.

2. The method according to claim 1, characterized in that The step of determining a target power flow equation of the meshing node according to the operating state of the meshing node and the initial power flow equation includes: Identifying a meshing type node that adopts a meshing type control mode among the new energy nodes; According to the operating status of the meshing node, the initial power flow equation is updated to a first power flow equation; According to the operating state of the meshing node and the steady-state current limiting control mode of the meshing node, the first power flow Jacobian matrix corresponding to the first power flow equation is updated to a second power flow Jacobian matrix, and the second power flow Jacobian matrix is ​​the Jacobian matrix corresponding to the target power flow equation.

3. The method according to claim 2, characterized in that The identifying the meshing type nodes that adopt the meshing type control mode among the new energy nodes includes: Traversing the new energy nodes and checking the control mode of the target node among the new energy nodes; If the control mode is the meshing control mode, the target node is marked as the meshing node.

4. The method according to claim 2, characterized in that The updating of the initial power flow equation to a first power flow equation according to the operating state of the meshed node includes: Setting the meshing node as a system regulation node, and constructing an unbalanced power flow equation for the meshing node based on the voltage amplitude and active current of the meshing node in the topological network of the power grid system, the reactive power of nodes connected to the meshing node, and the conductance, susceptance, and phase angle difference between different nodes in the topological network in the operating state; The unbalanced power flow equation and the initial power flow equation are combined into the first power flow equation.

5. The method according to claim 2, characterized in that The updating of the first power flow Jacobian matrix corresponding to the first power flow equation to a second power flow Jacobian matrix according to the operating state of the meshing node and the steady-state current limiting control mode of the meshing node includes: Calculating each element of the first power flow Jacobian matrix according to the solution of the first power flow equation, wherein the solution includes active power, reactive power, phase angle, and voltage stability parameter of the grid-forming node; determining the real part of the principal characteristic root of the first power flow Jacobian matrix; Determining a total current amplitude of the meshing node according to the active power, reactive power and voltage amplitude of the meshing node in the operating state; If the total current amplitude is greater than or equal to the current limiting threshold, updating the first power flow equation to the target power flow equation according to the real part of the main characteristic root of the first power flow Jacobian matrix and the steady-state current limiting control mode; The first power flow Jacobian matrix is ​​updated according to the partial derivatives of the voltage amplitude and the phase angle in the target power flow equation to obtain the second power flow Jacobian matrix.

6. The method according to claim 5, characterized in that The updating of the first power flow equation to the target power flow equation according to the real part of the main characteristic root of the first power flow Jacobian matrix and the steady-state current limiting control mode includes: If the steady-state current limiting control mode is the active power priority mode, setting the meshing node to a first-type node with constant active power and current output, and adding a current constraint equation to the first power flow equation to obtain the target power flow equation; If the steady-state current limiting control mode is the reactive power priority mode, the grid-forming node is set as a second type of node without active power, and the active power equation is deleted from the first power flow equation and the current constraint equation is added to obtain the target power flow equation.

7. The method according to claim 2, characterized in that The analyzing, based on the target power flow equation, the stability of the static voltage of the grid-connected power generation of the new energy node in the power grid system includes: According to the main characteristic root of the second power flow Jacobian matrix and the load coefficient of the meshed node, a critical point at which the voltage of the meshed node is in an unstable state is determined, and the critical point is continuously iterated until the voltage corresponding to the critical point converges to a target static voltage, wherein when the real part of the main characteristic root is 0, the target voltage value corresponding to the load coefficient of the meshed node is the static voltage of the critical point.

8. The method according to claim 7, characterized in that The method further comprises: determining, based on the principal characteristic root of the second power flow Jacobian matrix and the load coefficient of the meshed node, a critical point at which the voltage of the meshed node is in an unstable state, and continuously iterating the critical point until the voltage corresponding to the critical point converges to a target static voltage. generating, according to the principal characteristic root of the second power flow Jacobian matrix and the load coefficient of the meshed node, a target curve in which the real part of the principal characteristic root varies with the load coefficient; According to a preset step size and iteration coefficient, the critical point where the voltage of the meshed node is in an unstable state is detected point by point in the target curve; if the real part of the characteristic root corresponding to the target point in the target curve changes from a negative value to a positive value, the target point is used as the critical point, and the load factor corresponding to the target point is used as the static voltage limit threshold; If the real part of the characteristic root corresponding to the target point is a negative value, the target point is continuously iterated until the voltage corresponding to the target point converges to the target static voltage, and the target static voltage is less than or equal to the static voltage limit threshold.

9. The method according to claim 8, characterized in that After continuously iterating the target point until the voltage corresponding to the target point converges to the target static voltage, the method further includes: Visualizing the target curve and the target point corresponding to the target static voltage; The maximum load factor corresponding to the target static voltage is output.

10. A static voltage stability analysis device based on renewable energy grid-connected power generation, characterized in that: The device comprises: An acquisition module is used to obtain the operating status of new energy nodes in the power grid system; a determination module, configured to determine a target power flow equation of the grid-forming node based on an operating state of the grid-forming node and an initial power flow equation, wherein the target power flow equation is used to analyze the stability of the static voltage of the new energy node during grid-connected power generation in the power grid system, wherein the grid-forming node is a node among the new energy nodes that adopts a grid-forming control mode; An analysis module is used to analyze the stability of the static voltage of the new energy node connected to the grid for power generation in the power grid system based on the target power flow equation.

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