Planning method, device and electronic equipment of back-to-back flexible interconnection device of power grid

Abstract

A planning method, apparatus, and electronic device for back-to-back flexible interconnection devices of a power grid are disclosed. The method includes: acquiring initial operating state data of the power grid; determining candidate planning schemes for the power grid based on the initial operating state data and a set of target constraints; determining first updated operating state data of the power grid based on the set of target constraints and the candidate planning schemes; verifying the candidate planning schemes based on the first updated operating state data to obtain a first verification result, wherein the first verification result indicates the operational feasibility of the candidate planning scheme; and obtaining the target planning scheme for the power grid based on the first verification result. This solves the technical problem of inaccurate planning results for back-to-back flexible interconnection devices of power grids in related technologies.

Description

Technical Field

[0001] This relates to the field of power systems, and more specifically, to a planning method, apparatus, and electronic equipment for a back-to-back flexible interconnection device for power grids. Background Technology

[0002] With the advancement of new power system construction, some large receiving-end urban power grids have adopted a "multi-station, multi-zone" structure, where multiple 500kV substations serve as power supply points, jointly driving a 220kV zoned power grid. While ensuring power supply reliability, this structure also faces challenges such as close interconnection between 500kV / 220kV electromagnetic ring networks, continuously rising short-circuit current levels, and insufficient controllability of power flow between zones. Employing back-to-back flexible interconnection devices to link adjacent zones of the urban power grid can flexibly adjust the direction and magnitude of power flow between zones and appropriately compensate for dynamic reactive power, making it an important means to improve the flexible adjustment capability and safety stability of the urban power grid.

[0003] However, back-to-back flexible interconnection devices have high investment costs and complex operational constraints. Their site selection and capacity configuration directly determine the operational performance and engineering economics of the devices. Existing planning methods for back-to-back flexible interconnection devices have the following shortcomings: Firstly, existing planning methods often use simplified equivalent or static indicators for site selection, failing to fully consider the modulation ratio constraints, capacity constraints, control mode constraints, and back-to-back DC coupling constraints of back-to-back flexible interconnection devices based on VSC (Voltage Source Converter) converter stations, leading to planning results that may be infeasible in actual operation. Secondly, the embedding of back-to-back flexible interconnection devices causes the power flow equations to exhibit non-convex and nonlinear characteristics. Existing methods often use heuristic algorithms or Mixed-Integer Nonlinear Programming (MINLP) for direct solution, resulting in low computational efficiency and difficulty in guaranteeing global optimality, making it difficult to meet the planning needs of large-scale urban power grids. Thirdly, existing planning methods are mostly single-layer planning, failing to fully consider the constraints of typical operating scenarios such as renewable energy fluctuations and load growth on the actual operational performance of back-to-back flexible interconnection devices, potentially leading to insufficient renewable energy absorption or equipment overload in extreme scenarios. Therefore, there is a technical problem in the related technologies where the planning results of back-to-back flexible interconnection devices for power grids are inaccurate.

[0004] There is currently no effective solution to the above problems. Summary of the Invention

[0005] The embodiments provide a planning method, apparatus, and electronic equipment for back-to-back flexible interconnection devices of power grids, so as to at least solve the technical problem of inaccurate planning results of back-to-back flexible interconnection devices of power grids in related technologies.

[0006] According to one aspect of the embodiments, a planning method for back-to-back flexible interconnection devices in a power grid is provided, comprising: acquiring initial operating state data of the power grid, wherein the initial operating state data is acquired when no back-to-back flexible interconnection devices are installed in the power grid, and the back-to-back flexible interconnection devices include two VSC converter stations; determining candidate planning schemes for the power grid based on the initial operating state data and a set of target constraints, wherein the set of target constraints includes steady-state operation constraints of the power grid, operating characteristic constraints of the back-to-back flexible interconnection devices, and location and capacity constraints of the back-to-back flexible interconnection devices, and the candidate planning schemes are used to indicate the multiple VSC converter stations included in the multiple back-to-back flexible interconnection devices planned to be installed in the power grid. The installation locations of the C converter stations and the rated capacities of the multiple VSC converter stations are determined. Based on the target constraint set and candidate planning schemes, the first updated operating status data of the power grid is determined. This first updated operating status data is obtained when the power grid has installed back-to-back flexible interconnection devices according to the candidate planning schemes and is in typical operating scenarios, including renewable energy fluctuation scenarios and load growth scenarios. Based on the first updated operating status data, the candidate planning schemes are verified to obtain the first verification result, which is used to indicate the operational feasibility of the candidate planning schemes. Based on the first verification result, the target planning scheme of the power grid is obtained.

[0007] According to another aspect of the embodiments, a planning device for back-to-back flexible interconnection devices of a power grid is provided, comprising: a data acquisition module, configured to acquire initial operating state data of the power grid, wherein the initial operating state data is acquired when the back-to-back flexible interconnection devices are not installed in the power grid, and the back-to-back flexible interconnection devices include two VSC converter stations; and a first determination module, configured to determine candidate planning schemes for the power grid based on the initial operating state data and a target constraint set, wherein the target constraint set includes steady-state operation constraints of the power grid, operating characteristic constraints of the back-to-back flexible interconnection devices, and location and capacity constraints of the back-to-back flexible interconnection devices, and the candidate planning schemes are used to indicate the distribution of multiple VSC converter stations included in the multiple back-to-back flexible interconnection devices planned to be installed in the power grid. The system includes: a first determination module, which determines the first updated operating status data of the power grid based on the target constraint set and candidate planning schemes; a second determination module, which determines the first updated operating status data of the power grid based on the target constraint set and candidate planning schemes, wherein the first updated operating status data is obtained when the power grid has installed back-to-back flexible interconnection devices according to the candidate planning schemes and is in a typical operating scenario, including new energy fluctuation scenario and load growth scenario; a verification module, which verifies the candidate planning schemes based on the first updated operating status data and obtains a first verification result, wherein the first verification result is used to indicate the operational feasibility of the candidate planning schemes; and a target planning scheme determination module, which determines the target planning scheme of the power grid based on the first verification result.

[0008] According to another aspect of the embodiments, a non-volatile storage medium is provided that stores a plurality of instructions adapted for a planning method of a back-to-back flexible interconnection device for a power grid, any one of which is loaded and executed by a processor.

[0009] According to another aspect of the embodiments, an electronic device is provided, including: one or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement any one of the planning methods for a back-to-back flexible interconnection device of a power grid.

[0010] According to another aspect of the embodiments of this application, a computer program product is provided, which, when executed on a data processing device, is adapted to perform the planning method steps of a back-to-back flexible interconnection device for a power grid.

[0011] In this embodiment, initial operating state data of the power grid is acquired before the installation of back-to-back flexible interconnection devices (including two VSC converter stations). Based on the initial operating state data and a set of target constraints, candidate planning schemes for the power grid are determined. The target constraint set includes steady-state operation constraints of the power grid, operating characteristic constraints of the back-to-back flexible interconnection devices, and location and capacity constraints of the back-to-back flexible interconnection devices. The candidate planning schemes indicate the installation locations of the multiple VSC converter stations included in the planned back-to-back flexible interconnection devices in the power grid. The system includes the rated capacity of multiple VSC converter stations; based on the target constraint set and candidate planning schemes, it determines the first updated operating status data of the power grid. This first updated operating status data is obtained when the power grid has installed back-to-back flexible interconnection devices according to the candidate planning schemes and is in typical operating scenarios, including renewable energy fluctuation scenarios and load growth scenarios. Based on the first updated operating status data, the candidate planning schemes are verified to obtain the first verification result, which indicates the operational feasibility of the candidate planning schemes. Based on the first verification result, the target planning scheme of the power grid is obtained. This achieves the goal of determining and verifying candidate planning schemes for the power grid based on the initial operating status data and target constraint set, and finally obtaining the target planning scheme of the power grid based on the verification results. This improves the accuracy of the target planning scheme determination results for the power grid, thereby solving the technical problem of inaccurate planning results for back-to-back flexible interconnection devices in related technologies. Attached Figure Description

[0012] The accompanying drawings, which are provided to further understand the invention and form part of this application, illustrate exemplary embodiments and are used for explanation, and do not constitute an undue limitation of the invention. In the drawings:

[0013] Figure 1 This is a flowchart of a planning method for a back-to-back flexible interconnection device for a power grid, provided according to an embodiment;

[0014] Figure 2 This is a flowchart of an optional planning method for a back-to-back flexible interconnection device for a power grid, provided according to an embodiment;

[0015] Figure 3 This is a schematic diagram of an optional power grid planning result provided according to an embodiment;

[0016] Figure 4 This is a schematic diagram of a planning device for a back-to-back flexible interconnection device for a power grid, provided according to an embodiment.

[0017] Figure 5 This is a structural diagram of an electronic device provided according to an embodiment of this application. Detailed Implementation

[0018] To enable those skilled in the art to better understand the solutions, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments, not all of the embodiments. Based on the embodiments described, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection.

[0019] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0020] It should be noted that the information and data collected in this application (including but not limited to initial operating status data) are information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, storage, use, processing, transmission, provision, disclosure, and application of this data all comply with relevant laws, regulations, and standards, and necessary confidentiality measures have been taken. This process does not violate public order and good morals, and corresponding access points are provided for users to choose whether to authorize or refuse. For example, interfaces are set up between this system and relevant users or organizations, providing users with corresponding access points to choose whether to agree to or refuse the automated decision-making results; if the user chooses to refuse, the process proceeds to the expert decision-making stage.

[0021] According to an embodiment, a method embodiment for planning a back-to-back flexible interconnection device for a power grid is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0022] Figure 1 This is a flowchart of a planning method for a back-to-back flexible interconnection device for a power grid, provided according to an embodiment. Figure 1 As shown, the method includes the following steps:

[0023] Step S102: Obtain the initial operating status data of the power grid. The initial operating status data is obtained when the back-to-back flexible interconnection device is not installed in the power grid. The back-to-back flexible interconnection device includes two VSC converter stations.

[0024] It is understandable that by obtaining the initial operating status data of the power grid before the installation of back-to-back flexible interconnection devices, the differences in the power grid status before and after the commissioning of back-to-back flexible interconnection devices can be accurately quantified, thereby laying the foundation for the planning of back-to-back flexible interconnection devices.

[0025] Optionally, back-to-back flexible interconnection devices can be constructed based on VSC converter stations to establish connections between multiple zones within the power grid, enabling flexible and controllable regulation of power flow between zones and independent decoupling control of active and reactive power. A back-to-back flexible interconnection device consists of two VSC converter stations (converters with VSC as the core power conversion unit) connected back-to-back, linked by a DC bus. VSC converter stations can adopt an MMC topology, which combines the DC fault clearing capability of a half-bridge topology with the lower number of switching devices (i.e., better economic efficiency) of a full-bridge topology.

[0026] Step S104: Based on the initial operating status data and the target constraint set, determine the candidate planning scheme of the power grid. The target constraint set includes the steady-state operation constraints of the power grid, the operating characteristic constraints of the back-to-back flexible interconnection devices, and the location and capacity constraints of the back-to-back flexible interconnection devices. The candidate planning scheme is used to indicate the installation location of the multiple VSC converter stations included in the multiple back-to-back flexible interconnection devices planned to be installed in the power grid, and the rated capacity of the multiple VSC converter stations.

[0027] It is understandable that, based on the initial operating state data and the target constraint set, a high-level site selection and capacity pre-planning model is used to obtain candidate planning schemes for the power grid. The steady-state operation constraints of the power grid ensure that, after the planned scheme is implemented, the voltage, power flow distribution, and component load rate of each node in the power grid meet the physical safety and operational boundary requirements, thus guaranteeing the operational stability of the power grid. The operational characteristic constraints of the back-to-back flexible interconnection devices are used to accurately characterize the power injection capability and safe operating limits of the VSC under different modulation ratios, DC voltages, and control modes, ensuring the controllability and feasibility of the back-to-back flexible interconnection devices at the electrical and physical level. The site selection and capacity constraints of the back-to-back flexible interconnection devices are used to determine the optimal installation location, configuration quantity, and capacity size conforming to engineering modular standards, achieving optimized configuration of investment costs and power grid mutual support capabilities. By synergistically considering the power grid physical safety boundaries, device electrical operating limits, and engineering configuration constraints, global synergistic optimization of the site selection, capacity, and operational characteristics of the back-to-back flexible interconnection devices is achieved, thereby maximizing regional mutual support capabilities and investment economy while ensuring the safe and stable operation of the power grid.

[0028] In an optional embodiment, before determining candidate planning schemes for the power grid based on initial operating state data and a target constraint set, the method further includes: constructing an initial constraint set; relaxing constraints in the initial constraint set that do not satisfy convexity to obtain a target constraint set, wherein convexity refers to the fact that the feasible region defined by the constraint is a convex set.

[0029] It is understandable that, in order to overcome the loss of global optimality and the difficulty in solving the problem caused by the non-convex constraints in the initial constraint set, a second-order cone programming relaxation method is used to relax the constraints that do not satisfy convexity in the initial constraint set, resulting in a target constraint set. All constraints in this target constraint set satisfy the convexity characteristic, meaning that the feasible region it defines is a convex set, and the line connecting any two points in the feasible region is completely contained within the feasible region. This supports the use of efficient convex optimization algorithms to achieve a globally optimal solution. By transforming non-convex constraints into convex constraints through second-order cone programming relaxation, the local optimum trap caused by non-convexity is eliminated while preserving the globally optimal solution, thereby improving the solution efficiency and the global optimality of the solution to the power grid location and capacity determination problem.

[0030] Optionally, the steady-state operation constraints of the power grid in the initial constraint set include power balance constraints, generator output boundary constraints, node voltage amplitude boundary constraints, new energy output boundary constraints, and line thermal stability limit constraints; the operating characteristic constraints of back-to-back flexible interconnection devices in the initial constraint set include VSC power injection constraints, back-to-back DC coupling constraints (including back-to-back DC power coupling constraints and back-to-back DC voltage constraints), VSC apparent power constraints, VSC rated capacity constraints, modulation ratio constraints, equivalent power angle boundary constraints, DC voltage upper and lower limit constraints, and control mode constraints (including sending-end constant active power control constraints and receiving-end constant DC voltage control constraints); the location and capacity constraints of back-to-back flexible interconnection devices in the initial constraint set include location binary decision variable constraints, installation quantity constraints, back-to-back flexible interconnection device capacity configuration constraints, and modular discrete capacity constraints.

[0031] Optionally, power balance constraints are established. For any AC bus i in the power grid that does not have a VSC converter station installed, its active power balance equation and reactive power balance equation are as follows:

[0032]

[0033]

[0034] in, , These represent the active and reactive power outputs of the node represented by AC bus i, respectively. , These represent the active and reactive power outputs of new energy sources at node i, respectively. , These represent the active and reactive loads of node i, respectively. , They are nodes and AC bus The voltage amplitude of the node is represented; , These are the real and imaginary parts of the corresponding elements in the nodal admittance matrix, respectively; For nodes and The voltage phase angle difference between them; Let i be the set of all adjacent nodes that are directly connected to node i.

[0035] Optionally, for any AC bus i in the power grid equipped with a VSC converter station, its active power balance equation and reactive power balance equation are as follows:

[0036]

[0037]

[0038] in, , These represent the active and reactive power injected into the grid by the VSC converter installed at node i, with the injection into the AC bus as the positive direction.

[0039] Optionally, VSC power injection constraints are established. A back-to-back flexible interconnection device is installed between AC buses i and j, requiring the construction of corresponding VSC power injection constraints. The VSC converter station is configured as a two-port unit, connected to the grid via a transformer, and its turns ratio has been factored into the equivalent admittance. Let... The equivalent admittance between AC bus i and the VSC converter station is given. This is the equivalent reactance of the sum of the leakage inductance of the connecting transformer and the inductance of the MMC bridge arm. The angular frequency of the power grid. To connect the equivalent leakage inductance of the transformer, Let be the equivalent inductance of a single submodule arm of the MMC. Then, the active and reactive power injected by the VSC converter station into AC bus i satisfies:

[0040]

[0041]

[0042] in, and These are the equivalent power angle and modulation ratio of the VSC converter station connected to AC bus i, respectively; and These are the voltage amplitude of AC bus i and the DC side voltage of the connected VSC converter station, respectively. The equivalent admittance between AC bus i and the connected VSC converter station; The DC voltage utilization rate is determined by the PWM (Pulse Width Modulation) modulation strategy of the VSC converter station, and is generally [value missing]. The value can be taken as 0.866.

[0043] Optionally, back-to-back DC coupling constraints are established, including back-to-back DC power coupling constraints and back-to-back DC voltage constraints. The flexible interconnection device adopts a back-to-back structure, with the DC sides of the two VSC converter stations directly connected to the same DC bus. There are no long-distance DC lines, so the DC voltages at both ends are equal. At the same time, when the internal losses of the VSC converter station are ignored, the active power absorbed from the grid at one end is equal to the active power injected into the grid at the other end.

[0044] The back-to-back DC power coupling constraints are as follows:

[0045]

[0046] The back-to-back DC voltage constraints are as follows:

[0047]

[0048] in, The DC side voltage of the VSC converter station connected to AC bus j.

[0049] Optionally, converter station operating boundary constraints are established, including VSC apparent power constraints, VSC rated capacity constraints, modulation ratio constraints, equivalent power angle boundary constraints, DC voltage upper and lower limit constraints, and control mode constraints. By constructing these converter station operating boundary constraints, the controllable operation of both converter stations within a safe range is ensured, preventing overload of the back-to-back flexible interconnect device and ensuring that the operating point remains within a controllable range. Based on the VSC power injection constraints, the following constraints are eliminated: We can obtain:

[0050]

[0051] The power operating range of a VSC converter station is limited by the maximum voltage modulation ratio, the minimum voltage modulation ratio, and the arm current. Furthermore, based on the modular design of the MMC, the rated capacity of the VSC converter station is determined by the rated arm current. With DC side voltage Decision. The apparent power constraints of VSC are as follows:

[0052]

[0053]

[0054] VSC rated capacity constraints are as follows:

[0055]

[0056] in, .

[0057] The modulation ratio is constrained as follows:

[0058]

[0059] The equivalent work angle boundary constraints are as follows:

[0060]

[0061] The upper and lower limits of DC voltage are constrained as follows:

[0062]

[0063] in, The rated apparent power of the VSC converter station at AC bus i is the converter station capacity. and These are the upper and lower limits of the modulation ratio of the VSC converter station at AC bus i, respectively. and These represent the upper and lower limits of the voltage at the VSC converter station at AC bus i, respectively.

[0064] Optionally, the control mode constraints include constant active power control constraints at the sending end and constant DC voltage control constraints at the receiving end. The control mode of the VSC converter is specified to determine the solution boundary, typically configured as constant active power at the sending end and constant DC voltage at the receiving end, and control mode constraints are established accordingly.

[0065] The active power control constraints at the sending end are as follows:

[0066]

[0067] The control constraints of the fixed DC voltage are as follows:

[0068]

[0069] in, and These are the active power setting value of the VSC converter station at AC bus i and the DC side voltage setting value of the VSC converter station at AC bus j, respectively.

[0070] Optionally, boundary constraints for AC system components can be established, including generator output boundary constraints, node voltage amplitude boundary constraints, renewable energy output boundary constraints, and line thermal stability limit constraints. On the AC side, generators, renewable energy sources, node voltages, and the transmission power of AC lines must all meet the corresponding operating boundaries to ensure the safe and stable operation of the urban power grid after the flexible interconnection device is connected.

[0071] The generator output boundary constraints are as follows:

[0072]

[0073]

[0074] The boundary constraints for node voltage amplitude are as follows:

[0075]

[0076] The boundary constraints for new energy power output are as follows:

[0077]

[0078] The thermal stability limit constraints of the line are as follows:

[0079]

[0080] in, and These represent the upper and lower limits of the active power injected into the generator at AC bus i, respectively. and These are the upper and lower limits of reactive power injected into the generator at AC bus i, respectively. and These are the upper and lower limits of the bus voltage at point i on the AC busbar; The upper limit of active power injected into the new energy source at AC bus i; For the active power flow on the flexible interconnection channel between AC bus i and j; This is the upper limit of active power flow on the flexible interconnection channel between AC buses i and j.

[0081] Optionally, constraints can be established for binary decision variables in site selection, installation quantity, capacity configuration of back-to-back flexible interconnection devices, and modular discrete constraints. At the planning level, the installation location, quantity, and capacity configuration of back-to-back flexible interconnection devices must meet the constraints of site selection decision and engineering configuration. Considering that the configured capacity of the VSC converter station must be greater than the maximum transmission power of its controlled interconnection lines with a certain safety margin, and that the back-to-back flexible interconnection devices adopt a modular multilevel converter structure, their rated capacity should be discretely configured in integer multiples of standard modular units.

[0082] The constraints of the binary decision variables for location selection are as follows:

[0083]

[0084] The installation quantity constraints are as follows:

[0085]

[0086] The capacity configuration constraints for back-to-back flexible interconnect devices are as follows:

[0087]

[0088] The modular discrete constraints are as follows:

[0089]

[0090] in, For binary decision variables, This indicates that a VSC converter station is configured at node i. Indicates no configuration; This represents the maximum number of VSC converter stations that are allowed to be configured in the power grid. The rated capacity of the VSC converter station at AC bus i; Rated capacity of a single submodule in a VSC converter station; A positive integer represents The for of times; This is the set of nodes corresponding to all candidate installation locations in the power grid. This is the capacity margin coefficient.

[0091] Optionally, among the above constraints, the power balance constraint includes a coupling term between the node voltage magnitude and the phase angle difference. and VSC power injection constraints include coupling terms of modulation ratio, AC voltage, DC voltage, and equivalent power angle. and This results in a mixed-integer nonlinear programming (MINLP) problem that is nonconvex overall, making it difficult to solve and prone to getting trapped in local optima. To improve computational efficiency and ensure global optimality, a second-order cone programming relaxation method is used to relax the nonconvex constraints, thus transforming it into a mixed-integer second-order cone programming model.

[0092] Alternatively, non-convex nonlinear terms can be linearized by introducing auxiliary variables, and non-convex equality relations and bilinear product terms can be handled by using rotational cone constraints and McCormick convex envelopes respectively to obtain convex relaxation constraints.

[0093] First, auxiliary variables for AC power flow and VSC power are introduced to replace the nonlinear product terms in the original constraints with new independent variables, laying the foundation for subsequent linearization. The auxiliary variables for AC power flow and VSC power are as follows:

[0094]

[0095]

[0096]

[0097]

[0098]

[0099]

[0100] in, The square of the voltage amplitude at AC bus i; and These are the real and imaginary coupling variables of the voltage phasor between AC bus i and j, respectively; and These are the equivalent coupling variables of the active and reactive power channels of the VSC converter station connected at AC bus i, respectively. It is an auxiliary variable representing the product of the modulation ratio and the DC side voltage of the VSC converter station connected at AC bus i.

[0101] Optionally, based on the aforementioned auxiliary variables, the nonlinear product terms in the power balance constraints can be transformed into linear expressions. For any AC bus i in the power grid that does not have a VSC converter station installed, its relaxed active power balance equation and reactive power balance equation are as follows:

[0102]

[0103]

[0104] For any AC bus i in the power grid equipped with a VSC converter station, its relaxed active power balance equation and reactive power balance equation are as follows:

[0105]

[0106]

[0107] Where, when i=j, we have = , =0, the above formula will automatically include AC bus self-admittance.

[0108] because Since the equation is non-convex, relaxation is performed using the following rotating cone constraint:

[0109]

[0110] Meanwhile, the auxiliary variables satisfy symmetry constraints:

[0111]

[0112]

[0113] Similarly, substituting the auxiliary variables into the VSC power injection constraint equations transforms them into a linear form. For a VSC converter station connected at AC bus i, its relaxed active power equation and reactive power equation satisfy:

[0114]

[0115]

[0116] because Since the equation is non-convex, relaxation is performed using the following rotating cone constraint:

[0117]

[0118] because For bilinear product terms, directly introducing the aforementioned rotating cone constraint still cannot guarantee convexity. Therefore, the McCormick convex envelope method is used to linearize the bilinear terms. Combined with the modulation ratio boundary of the VSC converter station... , ] and DC voltage boundary[ , Construct the following linear constraints:

[0119]

[0120]

[0121]

[0122]

[0123] Introducing auxiliary variables Subsequently, the original node voltage amplitude boundary constraints need to be adjusted accordingly. Replacing the voltage amplitude with the square of the voltage amplitude, the following boundary constraints are constructed:

[0124]

[0125] In the formula, , = , , are the upper and lower limits of the square of the voltage amplitude at AC bus i, respectively.

[0126] Optionally, other constraints such as modulation ratio constraints, equivalent power angle boundary constraints, VSC rated capacity constraints, and DC voltage upper and lower limit constraints remain unchanged in form during convex relaxation and can be directly used.

[0127] In an optional embodiment, candidate planning schemes for the power grid are determined based on initial operating state data and a set of target constraints. This includes: obtaining candidate planning schemes by adopting an upper-level location and capacity pre-planning model based on the initial operating state data and the set of target constraints. The upper-level location and capacity pre-planning model includes a first objective function and first constraints. The first objective function aims to minimize investment costs, regional imbalance, and power supply security risks. The first constraints include investment budget constraints, paired installation constraints, and installation location screening constraints.

[0128] First objective function for:

[0129]

[0130] in, To normalize investment costs, For partition imbalance, For power supply safety redundancy, The penalty coefficient is... The weighting coefficient for investment costs. The weighting coefficients for partition imbalance. The weighting coefficient for power supply safety redundancy.

[0131] It is understandable that the investment budget constraint is used to limit the total annual equivalent investment cost of back-to-back flexible interconnection devices to no more than the funding limit set in the planning stage, ensuring the economic feasibility of the planning scheme; the paired installation constraint is used to mandate that the nodes at both ends of the channel of the cross-regional back-to-back flexible interconnection device must simultaneously construct VSC converter stations to ensure the physical integrity and operational necessity of the DC side electrical connection of the back-to-back flexible interconnection device; the installation location screening constraint is used to eliminate installation locations where the capacity ratio of two adjacent zones is lower than the lower limit, avoiding the establishment of interconnections between heavily loaded zones lacking mutual support potential, thereby reducing ineffective site selection and improving solution efficiency from the source. By constructing a multi-objective collaborative optimization model that takes into account investment economy, zone balance, and power supply security, the site selection and capacity planning scheme can be guided to achieve the comprehensive optimal goal of maximizing grid mutual support capacity and minimizing operational risks while meeting budget constraints and physical integrity requirements.

[0132] Optionally, the upper-level location and capacity pre-planning model focuses on the location and capacity pre-planning of back-to-back flexible interconnection devices, with the optimization objectives of minimizing investment costs, zonal imbalance, and power supply security risks. Unlike existing location methods that rely solely on topology contribution or static operating indicators, this method starts from the physical characteristics of power system operation, constructing zonal imbalance and power supply security redundancy indices. The zonal imbalance is weighted by the relative difference in capacity-to-load ratio and the coefficient of variation of main transformer load rate, quantifying the contribution of back-to-back flexible interconnection devices in balancing zonal power supply capacity and mitigating main transformer load differences, respectively. The power supply security redundancy index characterizes the power supply security margin of the weakest link in the power grid through the minimum main transformer redundancy. Simultaneously, an iterative adaptive feedback penalty term is introduced, transforming the over-limit information from the lower-level operation simulation into economic penalties for the upper-level location decision, guiding the optimization process to avoid suboptimal solutions.

[0133] Optionally, The investment cost is normalized and mapped to the [0,1] interval. The total investment cost of a back-to-back flexible interconnect device consists of two parts: fixed investment and variable investment, which are only included when the site selection decision is 1:

[0134]

[0135]

[0136]

[0137] in, The annual equivalent investment cost of back-to-back flexible interconnect devices; , These represent the minimum and maximum investment costs of candidate planning schemes during the pre-planning stage, respectively. Fixed installation costs for the device; This refers to the investment cost per unit of capacity. (Additional information) To ensure hour And in Time does not affect Normal value.

[0138] The zoning imbalance index comprehensively reflects the degree of difference in the capacity ratio of each zone after planning and the dispersion of the main transformer load rate:

[0139]

[0140] in, , The weights of each sub-indicator are given, and ; The difference lies in the relative capacity ratio; The constant is used for the pre-calculation of the coefficient of variation of the main transformer load rate.

[0141] The power supply safety redundancy index is taken as the minimum redundancy of each main transformer. Maximizing this minimum redundancy is equivalent to minimizing the power supply safety redundancy. :

[0142]

[0143]

[0144] in, Minimum redundancy for each main transformer; The power supply redundancy of the m-th main transformer; The total number of main transformers.

[0145] The iterative adaptive feedback penalty term transforms the limit-crossing information from the lower-level post-operation evaluation into an economic penalty for the upper-level location selection decision. Penalty coefficient. The following method is used to determine:

[0146]

[0147] in, The iterative adaptive penalty coefficient for the candidate installation location at node i is initially 0. If the index exceeds the limit after the lower layer runs, the penalty coefficient is accumulated according to the amount of the exceedance.

[0148] The relative difference in capacity ratio is defined as the weighted average of the deviations between the capacity ratio of each zone and the average capacity ratio of the entire network after interconnection. It is an optimization variable that dynamically changes with the site selection scheme.

[0149]

[0150] in, , These are the capacity ratios of the two adjacent partitions x and y of node i, respectively; This represents the average capacity ratio of the power grid.

[0151] The coefficient of variation of the main transformer load rate is initially pre-calculated using pre-planning grid static data (i.e., initial operating status data). Subsequent calculations use new operating status data returned from lower levels (e.g., first updated operating status data, second updated operating status data, etc.), such as the load rate. Iterative calculations are performed, where... For the first The load rate of the m-th main transformer in the next iteration. The coefficient of variation of the main transformer load rate is used as a constant in the upper-level objective function to avoid introducing non-convexity.

[0152]

[0153]

[0154] in, Standard deviation of main transformer load rate; The average load rate of the main transformer; Let be the load rate of the m-th main transformer in the r-th iteration.

[0155] Optionally, the upper-level site selection and capacity pre-planning must meet multiple constraints, including investment budget constraints, paired installation constraints, installation location screening constraints, and target constraint conditions.

[0156] Alternatively, the investment budget constraints are as follows:

[0157]

[0158] Cross-regional flexible interconnection channels require the simultaneous construction of VSC converter stations at both ends of the node; therefore, the following pairwise installation constraint is introduced:

[0159]

[0160] The installation location filtering constraints are as follows:

[0161]

[0162] in, , These are the capacity ratios of the two adjacent partitions x and y of node i under the running scenario s; This is the upper limit of the investment budget; This is the set of node pairs that need to be installed in pairs; This represents the lower limit of the capacity ratio under operating scenario s. When the capacity ratios of two adjacent partitions are both below the lower limit, it indicates that both partitions are under heavy load and do not have the conditions to support each other. In this case, the candidate installation locations are directly eliminated.

[0163] Step S106: Based on the target constraint set and candidate planning schemes, determine the first updated operating status data of the power grid. The first updated operating status data is obtained when the power grid has installed back-to-back flexible interconnection devices according to the candidate planning schemes and is in a typical operating scenario. Typical operating scenarios include new energy fluctuation scenarios and load growth scenarios.

[0164] Understandably, based on the target constraint set and candidate planning schemes, a lower-level multi-scenario operation simulation model is used to obtain the first updated operating status data of the power grid under typical operating scenarios. By combining the candidate planning schemes with typical operating scenarios (new energy fluctuations and load growth), the first updated operating status data representing the actual operating status of the power grid after the installation of flexible interconnection devices is obtained, providing accurate physical feedback for the iterative optimization of the upper-level model, thereby ensuring that the obtained target planning scheme takes into account both economy and operational safety.

[0165] In an optional embodiment, the first updated operating status data of the power grid is determined based on the target constraint set and candidate planning schemes, including: obtaining the first updated operating status data by adopting a lower-level multi-scenario operation simulation model based on the candidate planning schemes and the target constraint set, wherein the lower-level multi-scenario operation simulation model includes a second objective function, which is used to maximize the comprehensive operating benefits of the power grid under typical operating scenarios.

[0166] Second objective function for:

[0167]

[0168] in, This is a collection of typical operating scenarios. Let be the probability of scenario s occurring. For time period sets, This represents the actual wind power absorption capacity during time period t under operating scenario s. The actual photovoltaic power absorbed during time period t under operating scenario s. This represents the amount of wind and solar power curtailed during time period t under operating scenario s. The line overload power during time period t under operating scenario s. This refers to the power received by the power grid from the back-to-back flexible interconnection device during time period t under operating scenario s. The unit wind power price for time period t under operating scenario s. The unit photovoltaic electricity price for time period t under operating scenario s. The penalty coefficient for wind and solar power curtailment. This is the line overload penalty coefficient. Cost per unit of electricity received.

[0169] Understandable. Based on and The difference between them is determined. The transmission power of the flexible interconnection channel ij (i.e., the flexible interconnection channel of the back-to-back flexible interconnection device composed of the VSC converter station connected at node i and the VSC converter station connected at node j) during time period t under the operating scenario s. Let be the power received by the power grid from the back-to-back flexible interconnection device during time period t under operating scenario s, i.e., the power received by the power grid through the flexible interconnection channel during time period t. By constructing a comprehensive operational benefit maximization objective function that includes renewable energy consumption revenue, curtailment and overload penalties, and power receiving costs, the actual operational economy and safety of the back-to-back flexible interconnection device can be quantitatively evaluated under typical operating scenarios. This guides the collaborative iteration of upper and lower layer models to find the optimal objective planning scheme that balances high renewable energy utilization, low system operating costs, and strong power supply reliability.

[0170] Optionally, the lower-level multi-scenario simulation model uses the candidate planning schemes given in the upper level. Based on this, the actual operating effect of back-to-back flexible interconnection devices is simulated and verified under typical operating scenarios. The scenario set covers operating conditions such as fluctuations in renewable energy output and load growth. With the goal of maximizing comprehensive operating benefits, the operating status data such as renewable energy consumption, line load rate, and voltage level under each typical operating scenario are determined to evaluate the operational feasibility of candidate planning schemes.

[0171] Optionally, the lower-level multi-scenario operation simulation model needs to satisfy multiple constraints in the target constraint condition set during operation to ensure the safe and stable operation of the power grid under each typical operation scenario.

[0172] Step S108: Based on the first updated running status data, the candidate planning scheme is verified to obtain a first verification result, wherein the first verification result is used to indicate the operational feasibility of the candidate planning scheme;

[0173] It is understandable that by conducting multi-dimensional feasibility verification of candidate planning schemes based on the first updated operational status data (such as curtailment rate, line overload, and ramping capability), the potential risks and limit-breaking issues of candidate planning schemes in actual operation can be accurately identified, thereby improving the rationality and feasibility of the target planning scheme.

[0174] In one optional embodiment, the candidate planning scheme is verified based on the first updated operating status data to obtain a first verification result, including: obtaining a second verification result based on the actual power consumption data in the first updated operating status data; obtaining a third verification result based on the wind and solar power curtailment in the first updated operating status data; obtaining a fourth verification result based on the line overload power in the first updated operating status data; obtaining a fifth verification result based on the power received in the first updated operating status data; if the second, third, fourth, and fifth verification results are all verified as passed, the first verification result is determined to be verified as passed; if any of the second, third, fourth, and fifth verification results fail to pass verification, the first verification result is determined to be verified as failed.

[0175] It is understood that the second verification result is obtained based on the actual power consumption data (e.g., actual wind power consumption and actual photovoltaic power consumption) and predicted output value in the first updated operating status data; the third verification result is obtained based on the wind and solar curtailment power and the maximum allowable wind and solar curtailment rate in the first updated operating status data; the fourth verification result is obtained based on the line overload power and preset line overload threshold in the first updated operating status data; and the fifth verification result is obtained based on the power received and the up / down adjustment rate limit of the conventional grid units in the first updated operating status data. If the second, third, fourth, and fifth verification results are all verified and passed, it indicates that the candidate planning scheme meets the constraints of new energy consumption, curtailment rate limit, equipment capacity, and grid power receiving capacity under typical operating scenarios, and has sufficient power receiving and regulation capacity, demonstrating the feasibility and safety of engineering operation. In this case, the first verification result is determined to be verified and passed. If any of the second, third, fourth, or fifth verification results fail, it indicates that the candidate planning scheme has operational defects in certain typical operating scenarios, such as insufficient renewable energy consumption, excessive curtailment rate, equipment overload, or insufficient power grid ramping capability, which cannot guarantee the safe and stable operation of the power grid. In this case, the first verification result is determined to be a failure. Through a multi-dimensional verification mechanism, the actual performance of the candidate planning scheme in terms of renewable energy consumption, equipment safety, and power grid regulation capability is comprehensively evaluated to ensure that the final target planning scheme is both economical and operationally feasible, thereby improving the engineering applicability and power supply reliability of the power grid regional flexible interconnection project.

[0176] Optionally, if the actual power consumption is less than or equal to the predicted output value, it indicates that no wind or solar power curtailment has occurred, and the second verification result is considered successful; otherwise, the verification is considered unsuccessful. If the wind or solar power curtailment is less than or equal to the maximum wind or solar power curtailment rate, it indicates that the wind or solar power curtailment rate has not exceeded the allowable value, and the third verification result is considered successful; otherwise, the verification is considered unsuccessful. If the line overload power is less than or equal to the preset line overload threshold, it indicates that the line overload power has not exceeded the limit, and the fourth verification result is considered successful; otherwise, the verification is considered unsuccessful. If the difference between the power received in the current period and the power received in the previous period is less than or equal to the limit of the upward / downward adjustment rate of the grid's conventional generating units, it indicates that the grid's power received has not exceeded its ramp-up capability, and the fifth verification result is considered successful; otherwise, the verification is considered unsuccessful.

[0177] Optionally, the second verification result is obtained by performing the following verification based on the actual power consumption data (e.g., actual wind power consumption and actual photovoltaic power consumption) in the new operating status data output by the lower-level multi-scenario operation simulation model.

[0178]

[0179]

[0180] in, , These represent the predicted available power output of wind power and solar power during time period t under operating scenario s.

[0181] Based on the new operational status data output by the lower-level multi-scenario operation simulation model, the following verification was performed to obtain the third verification result.

[0182]

[0183] in, The maximum allowable wind and solar curtailment rate.

[0184] Based on the line overload power in the new operating status data output by the lower-level multi-scenario operation simulation model, the following verification was performed, resulting in the fourth verification result.

[0185]

[0186] in, This is the preset line overload threshold.

[0187] The power received is verified based on the new operating status data output by the lower-level multi-scenario operation simulation model, resulting in the fifth verification result.

[0188]

[0189] in, These are the limits for the rate of increase / decrease of conventional generating units in the power grid.

[0190] Step S110: Based on the first verification result, obtain the target planning scheme for the power grid.

[0191] It is understandable that by conducting multi-dimensional verification of candidate planning schemes, the rationality and feasibility of the target planning scheme determination results can be improved.

[0192] In one optional embodiment, the target planning scheme for the power grid is obtained based on the first verification result, including: if the first verification result is verified as passed, the candidate planning scheme is iteratively optimized based on the first updated operating status data, using an upper-level addressing and capacity pre-planning model and a lower-level multi-scenario operation simulation model, to obtain the target planning scheme.

[0193] It is understandable that if the first verification result is successful, based on the first updated operating status data and the target constraint set, the upper-level location and capacity pre-planning model is used to obtain a new first objective function value and a new planning scheme. The new first objective function value is used to determine whether the first iteration stopping condition is met. If it is, the target planning scheme is obtained based on the candidate planning scheme and the new planning scheme. If not, based on the new planning scheme and the target constraint set, the lower-level multi-scenario operation simulation model is used to obtain the third updated operating status data. The new planning scheme is then verified based on the third updated operating status data to obtain the seventh verification result. The new planning scheme is then iteratively optimized based on the seventh verification result to finally obtain the target planning scheme. Through the upper and lower-level collaborative iterative optimization mechanism, the planning scheme is continuously optimized while ensuring its operational feasibility until the first objective function converges, thereby obtaining a globally optimal planning scheme that balances investment economy and power grid operation safety.

[0194] Optionally, the first iteration stopping condition is that the difference between two consecutive first objective function values ​​(e.g., the first objective function value corresponding to the candidate planning scheme and the new first objective function value) is less than the convergence precision. The above-mentioned process of obtaining the target planning scheme based on the candidate planning scheme and the new planning scheme means: if the candidate planning scheme and the new planning scheme are the same, then the candidate planning scheme is determined as the target planning scheme; if the candidate planning scheme and the new planning scheme are different, then the planning scheme corresponding to the iteration number with the smaller first objective function value is determined as the target planning scheme.

[0195] Optionally, the stopping condition for the first iteration is:

[0196]

[0197] in, , Let be the first objective function values ​​for the r-th iteration and the (r-1)-th iteration, respectively. For convergence accuracy.

[0198] Optionally, the planning scheme determination model based on the upper-level site selection and capacity pre-planning model and the lower-level multi-scenario operation simulation model also includes a second iteration stopping condition. The second iteration stopping condition refers to the number of iterations reaching the maximum number of iterations. The planning scheme corresponding to the maximum number of iterations is then determined as the target planning scheme.

[0199] In one optional embodiment, the target planning scheme for the power grid is obtained based on the first verification result, including: if the first verification result is a failure, adjusting the parameters of the back-to-back flexible interconnection device capacity configuration constraints in the upper-level site selection and capacity pre-planning model and the target constraint set to obtain an updated site selection and capacity pre-planning model and an updated constraint set; based on the initial operating state data and the updated constraint set, using the updated site selection and capacity pre-planning model to obtain an updated planning scheme; based on the updated constraint set and the updated planning scheme, using the lower-level multi-scenario operation simulation model to obtain second updated operating state data; based on the second updated operating state data, verifying the updated planning scheme to obtain a sixth verification result; and using the method of obtaining the target planning scheme, obtaining the target planning scheme based on the sixth verification result.

[0200] It is understandable that if the first verification result is a failure, the parameters of the capacity configuration constraints of the back-to-back flexible interconnection device in the upper-level site selection and capacity pre-planning model and the target constraint set (such as the weighting coefficient of investment cost, capacity margin coefficient, penalty coefficient, and the node set corresponding to the candidate installation location) are adjusted to obtain an updated site selection and capacity pre-planning model and an updated constraint set. Based on the initial operating status data and the updated constraint set, the updated site selection and capacity pre-planning model is used to obtain an updated planning scheme. Based on the updated constraint set and the updated planning scheme, the lower-level multi-scenario operation simulation model is used to obtain the second updated operating status data. The updated planning scheme is verified based on the second updated operating status data to obtain the sixth verification result. The updated planning scheme is iteratively optimized using the method of obtaining the target planning scheme based on the first verification result to obtain the target planning scheme. By dynamically adjusting the parameters of the upper-level site selection and capacity pre-planning model and the target constraint set when the lower-level verification fails, the optimization direction is guided to correct infeasible schemes, thereby achieving a globally optimal solution for the planning scheme that balances economy and feasibility while ensuring that the back-to-back flexible interconnection device meets the safety boundaries of multi-scenario operation.

[0201] Optionally, the capacity configuration constraints of back-to-back flexible interconnect devices in the upper-layer site selection and capacity pre-planning model and the target constraint set can be adjusted in the following way:

[0202] (1) Increase the weighting coefficient of investment cost in the upper-level site selection and sizing pre-planning model. ;

[0203] (2) Increase the capacity margin coefficient This will increase the lower limit of the rated capacity of VSC converter stations and improve capacity configuration;

[0204] (3) Add a penalty coefficient term to the first objective function;

[0205] (4) Screen out the candidate installation locations corresponding to nodes that have not passed the above verification, and narrow down the range of candidate installation locations.

[0206] Through the above steps S102 to S110, the candidate planning schemes of the power grid can be determined and verified based on the initial operating state data and target constraint set of the power grid. Finally, the target planning scheme of the power grid is obtained based on the verification results. This achieves the technical effect of improving the accuracy of the target planning scheme determination results of the power grid, thereby solving the technical problem of inaccurate planning results of back-to-back flexible interconnection devices of the power grid in related technologies.

[0207] Based on the above embodiments and optional embodiments, an implementation method for planning back-to-back flexible interconnection devices in a power grid is proposed. This optional implementation method can be understood as a method for site selection and capacity determination of VSC back-to-back flexible interconnection devices in multi-station, multi-zone urban power grids. By constructing an initial constraint set including steady-state operation constraints of the power grid, operating characteristic constraints of the back-to-back flexible interconnection devices, and site selection and capacity determination constraints of the back-to-back flexible interconnection devices, and employing a second-order cone programming relaxation technique to relax non-convex constraints, thereby transforming them into convex constraints, the method achieves coordinated optimization of the installation location and rated capacity configuration of the back-to-back flexible interconnection devices. Simultaneously, through a collaborative iterative mechanism between upper and lower layers, simulation results of multiple typical operating scenarios are fed back to the planning layer, ensuring that the obtained target planning scheme balances economic efficiency and operational feasibility, thereby improving the inter-regional mutual support capability and operational flexibility of the urban power grid. This method is applicable to the regional flexible interconnection planning under the "multi-station, multi-zone" structure of large receiving-end urban power grids.

[0208] By establishing constraints that consider the modulation ratio, capacity, control mode, and back-to-back DC coupling of VSC converter stations, and using MISOCP (Mixed-Integer Second-Order Cone Programming) technology for global optimal solution, the investment economy and operational benefits of back-to-back flexible interconnection devices can be effectively coordinated, providing a scientific site selection and capacity determination scheme for urban power grid zone flexible interconnection projects. Figure 2 This is a flowchart of an optional planning method for a back-to-back flexible interconnection device for a power grid, provided according to an embodiment. Figure 2As shown, the steps of the VSC back-to-back flexible interconnection device site selection and capacity determination method for multi-station and multi-area urban power grids include:

[0209] Step S1: Establish a steady-state operation model of the power grid and the back-to-back flexible interconnection device based on VSC converter station, including power balance constraints, VSC power injection constraints, back-to-back DC coupling constraints, and converter station operation boundary constraints, so as to fully describe the steady-state operation characteristics of the back-to-back flexible interconnection device after it is embedded in the urban power grid.

[0210] The VSC back-to-back flexible interconnect device adopts a back-to-back hybrid modular multilevel converter (MMC) topology. The hybrid MMC combines the characteristics of half-bridge and full-bridge topologies. Compared with the half-bridge topology, it has DC fault clearing capability, and compared with the full-bridge topology, it has a moderate number of switching devices and better economic benefits.

[0211] Establish power balance constraints. For any AC bus i in the power grid that does not have a VSC converter station installed, its active power balance equation and reactive power balance equation are as follows:

[0212]

[0213]

[0214] in, , These represent the active and reactive power outputs of the node represented by AC bus i, respectively. , These represent the active and reactive power outputs of new energy sources at node i, respectively. , These represent the active and reactive loads of node i, respectively. , They are nodes and AC bus The voltage amplitude of the node is represented; , These are the real and imaginary parts of the corresponding elements in the nodal admittance matrix, respectively; For nodes and The voltage phase angle difference between them; Let i be the set of all adjacent nodes that are directly connected to node i.

[0215] For any AC bus i in the power grid equipped with a VSC converter station, its active power balance equation and reactive power balance equation are as follows:

[0216]

[0217]

[0218] in, , These represent the active and reactive power injected into the grid by the VSC converter installed at node i, with the injection into the AC bus as the positive direction.

[0219] Establish VSC power injection constraints. A back-to-back flexible interconnection device is installed between AC buses i and j, requiring the construction of corresponding VSC power injection constraints. The VSC converter station is configured as a two-port unit, connected to the grid via a transformer, and its turns ratio has been factored into the equivalent admittance. Let... The equivalent admittance between AC bus i and the VSC converter station is given. This is the equivalent reactance of the sum of the leakage inductance of the connecting transformer and the inductance of the MMC bridge arm. The angular frequency of the power grid. To connect the equivalent leakage inductance of the transformer, Let be the equivalent inductance of a single submodule arm of the MMC. Then, the active and reactive power injected by the VSC converter station into AC bus i satisfies:

[0220]

[0221]

[0222] in, and These are the equivalent power angle and modulation ratio of the VSC converter station connected to AC bus i, respectively; and These are the voltage amplitude of AC bus i and the DC side voltage of the connected VSC converter station, respectively. The equivalent admittance between AC bus i and the connected VSC converter station; The DC voltage utilization rate is determined by the PWM (Pulse Width Modulation) modulation strategy of the VSC converter station, and is generally [value missing]. The value can be taken as 0.866.

[0223] Back-to-back DC coupling constraints are established, including back-to-back DC power coupling constraints and back-to-back DC voltage constraints. The flexible interconnection device adopts a back-to-back structure, with the DC sides of the two VSC converter stations directly connected to the same DC bus. There are no long-distance DC lines, so the DC voltages at both ends are equal. At the same time, neglecting the internal losses of the VSC converter stations, the active power absorbed from the grid at one end is equal to the active power injected into the grid at the other end.

[0224] The back-to-back DC power coupling constraints are as follows:

[0225]

[0226] The back-to-back DC voltage constraints are as follows:

[0227]

[0228] in, The DC side voltage of the VSC converter station connected to AC bus j.

[0229] Establish converter station operating boundary constraints, including VSC apparent power constraints, VSC rated capacity constraints, modulation ratio constraints, equivalent power angle boundary constraints, DC voltage upper and lower limit constraints, and control mode constraints. By constructing these operating boundary constraints, the controllable operation of both converter stations within a safe range is ensured, preventing overload of the back-to-back flexible interconnect device and ensuring that the operating point remains within a controllable range. Based on the VSC power injection constraints, eliminate... We can obtain:

[0230]

[0231] The power operating range of a VSC converter station is limited by the maximum voltage modulation ratio, the minimum voltage modulation ratio, and the arm current. Furthermore, based on the modular design of the MMC, the rated capacity of the VSC converter station is determined by the rated arm current. With DC side voltage Decision. The apparent power constraints of VSC are as follows:

[0232]

[0233]

[0234] VSC rated capacity constraints are as follows:

[0235]

[0236] in, .

[0237] The modulation ratio is constrained as follows:

[0238]

[0239] The equivalent work angle boundary constraints are as follows:

[0240]

[0241] The upper and lower limits of DC voltage are constrained as follows:

[0242]

[0243] in, The rated apparent power of the VSC converter station at AC bus i is the converter station capacity. and These are the upper and lower limits of the modulation ratio of the VSC converter station at AC bus i, respectively. and These represent the upper and lower limits of the voltage at the VSC converter station at AC bus i, respectively.

[0244] Control mode constraints include constant active power control constraints at the sending end and constant DC voltage control constraints at the receiving end. The control mode of the VSC converter is specified to determine the solution boundary. A typical configuration is constant active power at the sending end and constant DC voltage at the receiving end, and control mode constraints are established accordingly.

[0245] The active power control constraints at the sending end are as follows:

[0246]

[0247] The control constraints of the fixed DC voltage are as follows:

[0248]

[0249] in, and These are the active power setting value of the VSC converter station at AC bus i and the DC side voltage setting value of the VSC converter station at AC bus j, respectively.

[0250] Step S2: Establish site selection and capacity determination decisions and system boundary constraints, including site selection binary decision variable constraints, installation quantity constraints, back-to-back flexible interconnection device capacity configuration constraints, modular discrete constraints, and AC system component boundary constraints, forming a joint constraint set for planning and operation;

[0251] Establish boundary constraints for AC system components, including generator output boundary constraints, node voltage amplitude boundary constraints, renewable energy output boundary constraints, and line thermal stability limit constraints. On the AC side, generators, renewable energy sources, node voltages, and AC line transmission power must all meet the corresponding operating boundaries to ensure the safe and stable operation of the urban power grid after the flexible interconnection device is connected.

[0252] The generator output boundary constraints are as follows:

[0253]

[0254]

[0255] The boundary constraints for node voltage amplitude are as follows:

[0256]

[0257] The boundary constraints for new energy power output are as follows:

[0258]

[0259] The thermal stability limit constraints of the line are as follows:

[0260]

[0261] in, and These represent the upper and lower limits of the active power injected into the generator at AC bus i, respectively. and These are the upper and lower limits of reactive power injected into the generator at AC bus i, respectively. and These are the upper and lower limits of the bus voltage at point i on the AC busbar; The upper limit of active power injected into the new energy source at AC bus i; For the active power flow on the flexible interconnection channel between AC bus i and j; This is the upper limit of active power flow on the flexible interconnection channel between AC buses i and j.

[0262] Constraints are established based on binary decision variables for site selection, quantity constraints, capacity configuration constraints for back-to-back flexible interconnection devices, and modular discrete constraints. At the planning level, the installation location, quantity, and capacity configuration of back-to-back flexible interconnection devices must meet the constraints of site selection decisions and engineering configuration. Considering that the configured capacity of VSC converter stations must be greater than the maximum transmission power of the interconnected lines they control and leave a certain safety margin, and that the back-to-back flexible interconnection devices adopt a modular multilevel converter structure, their rated capacity should be discretely configured in integer multiples of standard modular units.

[0263] The constraints of the binary decision variables for location selection are as follows:

[0264]

[0265] The installation quantity constraints are as follows:

[0266]

[0267] The capacity configuration constraints for back-to-back flexible interconnect devices are as follows:

[0268]

[0269] The modular discrete constraints are as follows:

[0270]

[0271] in, For binary decision variables, This indicates that a VSC converter station is configured at node i. Indicates no configuration; This represents the maximum number of VSC converter stations that are allowed to be configured in the power grid. The rated capacity of the VSC converter station at AC bus i; Rated capacity of a single submodule in a VSC converter station; A positive integer represents The for of times; This is the set of nodes corresponding to all candidate installation locations in the power grid. This is the capacity margin coefficient.

[0272] Step S3 involves relaxing the non-convex constraints using mixed-integer second-order cone programming. An auxiliary variable is introduced to linearize the non-convex nonlinear terms in the power balance constraint and VSC power injection constraint. A rotating cone constraint is used to relax the non-convex equations, and McCormick's convex envelope is used to handle the bilinear product terms, transforming the original mixed-integer nonlinear programming model into an efficiently solvable MISOCP model.

[0273] Among the constraints mentioned above, the power balance constraint includes a coupling term between node voltage magnitude and phase angle difference. and VSC power injection constraints include coupling terms of modulation ratio, AC voltage, DC voltage, and equivalent power angle. and This results in a mixed-integer nonlinear programming (MINLP) problem that is nonconvex overall, making it difficult to solve and prone to getting trapped in local optima. To improve computational efficiency and ensure global optimality, a second-order cone programming relaxation method is used to relax the nonconvex constraints, thus transforming it into a mixed-integer second-order cone programming model.

[0274] Specifically, by introducing auxiliary variables to linearize the non-convex nonlinear terms, and by using the rotating cone constraint and McCormick convex envelope to handle the non-convex equality relations and bilinear product terms respectively, convex relaxation constraints are obtained.

[0275] First, auxiliary variables for AC power flow and VSC power are introduced to replace the nonlinear product terms in the original constraints with new independent variables, laying the foundation for subsequent linearization. The auxiliary variables for AC power flow and VSC power are as follows:

[0276]

[0277]

[0278]

[0279]

[0280]

[0281]

[0282] in, The square of the voltage amplitude at AC bus i; and These are the real and imaginary coupling variables of the voltage phasor between AC bus i and j, respectively; and These are the equivalent coupling variables of the active and reactive power channels of the VSC converter station connected at AC bus i, respectively. It is an auxiliary variable representing the product of the modulation ratio and the DC side voltage of the VSC converter station connected at AC bus i.

[0283] Based on the aforementioned auxiliary variables, the nonlinear product terms in the power balance constraints can be transformed into linear expressions. For any AC bus i in the power grid that does not have a VSC converter station installed, its relaxed active power balance equation and reactive power balance equation are as follows:

[0284]

[0285]

[0286] For any AC bus i in the power grid equipped with a VSC converter station, its relaxed active power balance equation and reactive power balance equation are as follows:

[0287]

[0288]

[0289] Where, when i=j, we have = , =0, the above formula will automatically include AC bus self-admittance.

[0290] because Since the equation is non-convex, relaxation is performed using the following rotating cone constraint:

[0291]

[0292] Meanwhile, the auxiliary variables satisfy symmetry constraints:

[0293]

[0294]

[0295] Similarly, substituting the auxiliary variables into the VSC power injection constraint equations transforms them into a linear form. For a VSC converter station connected at AC bus i, its relaxed active power equation and reactive power equation satisfy:

[0296]

[0297]

[0298] because Since the equation is non-convex, relaxation is performed using the following rotating cone constraint:

[0299]

[0300] because For bilinear product terms, directly introducing the aforementioned rotating cone constraint still cannot guarantee convexity. Therefore, the McCormick convex envelope method is used to linearize the bilinear terms. Combined with the modulation ratio boundary of the VSC converter station... , ] and DC voltage boundary[ , Construct the following linear constraints:

[0301]

[0302]

[0303]

[0304]

[0305] Introducing auxiliary variables Subsequently, the original node voltage amplitude boundary constraints need to be adjusted accordingly. Replacing the voltage amplitude with the square of the voltage amplitude, the following boundary constraints are constructed:

[0306]

[0307] In the formula, , = , , are the upper and lower limits of the square of the voltage amplitude at AC bus i, respectively.

[0308] Other constraints, such as modulation ratio constraints, equivalent power angle boundary constraints, VSC rated capacity constraints, and DC voltage upper and lower limit constraints, remain unchanged in form during convex relaxation and can be directly used.

[0309] Step S4: Establish an upper-level site selection and capacity planning model. With the optimization objectives of minimizing investment costs, regional imbalance, and power supply security risks, generate candidate site selection and capacity planning schemes (i.e., candidate planning schemes).

[0310] The upper-level location and capacity pre-planning model focuses on the location and capacity pre-planning of back-to-back flexible interconnection devices, aiming to minimize investment costs, regional imbalance, and power supply security risks. Unlike existing location methods that rely solely on topology contribution or static operating indicators, this method starts from the physical characteristics of power system operation, constructing regional imbalance and power supply security redundancy indices. The regional imbalance is weighted by the relative difference in capacity-to-load ratio and the coefficient of variation of transformer load rate, quantifying the contribution of back-to-back flexible interconnection devices in balancing regional power supply capacity and mitigating transformer load differences, respectively. The power supply security redundancy index characterizes the power supply security margin of the weakest link in the power grid through minimum transformer redundancy. Simultaneously, an iterative adaptive feedback penalty term is introduced, transforming the over-limit information from lower-level operation simulation into economic penalties for upper-level location decisions, guiding the optimization process to avoid suboptimal solutions. The upper-level comprehensive objective function (i.e., the first objective function) is as follows:

[0311]

[0312] in, To normalize investment costs, For partition imbalance, For power supply safety redundancy, The penalty coefficient is... The weighting coefficient for investment costs. The weighting coefficients for partition imbalance. The weighting coefficient for power supply safety redundancy.

[0313] The investment cost is normalized and mapped to the [0,1] interval. The total investment cost of a back-to-back flexible interconnect device consists of two parts: fixed investment and variable investment, which are only included when the site selection decision is 1:

[0314]

[0315]

[0316]

[0317] in, The annual equivalent investment cost of back-to-back flexible interconnect devices; , These represent the minimum and maximum investment costs of candidate planning schemes during the pre-planning stage, respectively. Fixed installation costs for the device; This refers to the investment cost per unit of capacity. (Additional information) To ensure hour And in Time does not affect Normal value.

[0318] The zoning imbalance index comprehensively reflects the degree of difference in the capacity ratio of each zone after planning and the dispersion of the main transformer load rate:

[0319]

[0320] in, , The weights of each sub-indicator are given, and ; The difference lies in the relative capacity ratio; The constant is used for the pre-calculation of the coefficient of variation of the main transformer load rate.

[0321] The power supply safety redundancy index is taken as the minimum redundancy of each main transformer. Maximizing this minimum redundancy is equivalent to minimizing the power supply safety redundancy. :

[0322]

[0323]

[0324] in, Minimum redundancy for each main transformer; The power supply redundancy of the m-th main transformer; The total number of main transformers.

[0325] The iterative adaptive feedback penalty term transforms the limit-crossing information from the lower-level post-operation evaluation into an economic penalty for the upper-level location selection decision. Penalty coefficient. The following method is used to determine:

[0326]

[0327] in, The iterative adaptive penalty coefficient for the candidate installation location at node i is initially 0. If the index exceeds the limit after the lower layer runs, the penalty coefficient is accumulated according to the amount of the exceedance.

[0328] The relative difference in capacity ratio is defined as the weighted average of the deviations between the capacity ratio of each zone and the average capacity ratio of the entire network after interconnection. It is an optimization variable that dynamically changes with the site selection scheme.

[0329]

[0330] in, , These are the capacity ratios of the two adjacent partitions x and y of node i, respectively; This represents the average capacity ratio of the power grid.

[0331] The coefficient of variation of the main transformer load rate is initially pre-calculated using pre-planning grid static data (i.e., initial operating status data). Subsequent calculations use new operating status data returned from lower levels (e.g., first updated operating status data, second updated operating status data, etc.), such as the load rate. Iterative calculations are performed, where... For the first The load rate of the m-th main transformer in the next iteration. The coefficient of variation of the main transformer load rate is used as a constant in the upper-level objective function to avoid introducing non-convexity.

[0332]

[0333]

[0334] in, Standard deviation of main transformer load rate; The average load rate of the main transformer; Let be the load rate of the m-th main transformer in the r-th iteration.

[0335] The upper-level site selection and capacity pre-planning must meet investment budget constraints, paired installation constraints, installation location screening constraints, and multiple constraints constructed in steps S1 and S2.

[0336] The investment budget constraints are as follows:

[0337]

[0338] Cross-regional flexible interconnection channels require the simultaneous construction of VSC converter stations at both ends of the node; therefore, the following pairwise installation constraint is introduced:

[0339]

[0340] The installation location filtering constraints are as follows:

[0341]

[0342] in, , These are the capacity ratios of the two adjacent partitions x and y of node i under the running scenario s; This is the upper limit of the investment budget; This is the set of node pairs that need to be installed in pairs; This represents the lower limit of the capacity ratio under operating scenario s. When the capacity ratios of two adjacent partitions are both below the lower limit, it indicates that both partitions are under heavy load and do not have the conditions to support each other. In this case, the candidate installation locations are directly eliminated.

[0343] Step S5: Establish a multi-scenario operation simulation model at the lower level. Under the given candidate site selection and capacity determination schemes at the upper level, conduct operation simulations based on typical scenarios such as new energy fluctuations and load growth, and verify the actual operation effect of the candidate site selection and capacity determination schemes with the goal of comprehensive operation benefits;

[0344] The lower-level multi-scenario simulation model uses the candidate planning schemes given in the upper level. Based on this, the actual operating effect of the back-to-back flexible interconnection device is simulated and verified according to typical operating scenarios. The scenario set covers operating conditions such as fluctuations in renewable energy output and load growth. With the goal of maximizing comprehensive operating benefits, the operating status data such as renewable energy consumption, line load rate, and voltage level under each typical operating scenario are determined to evaluate the operational feasibility of candidate planning schemes. The second objective function of the lower-level multi-scenario operation simulation model is as follows:

[0345]

[0346] in, This is a collection of typical operating scenarios. Let be the probability of scenario s occurring. For time period sets, This represents the actual wind power absorption capacity during time period t under operating scenario s. The actual photovoltaic power absorbed during time period t under operating scenario s. This represents the amount of wind and solar power curtailed during time period t under operating scenario s. The line overload power during time period t under operating scenario s is based on and The difference between them is determined. The transmission power of the flexible interconnection channel ij (i.e., the flexible interconnection channel of the back-to-back flexible interconnection device composed of the VSC converter station connected at node i and the VSC converter station connected at node j) during time period t under operating scenario s. This refers to the power received by the power grid from the back-to-back flexible interconnection device during time period t under operating scenario s (i.e., the power received by the power grid through the flexible interconnection channel during time period t). The unit wind power price for time period t under operating scenario s. The unit photovoltaic electricity price for time period t under operating scenario s. The penalty coefficient for wind and solar power curtailment. This is the line overload penalty coefficient. Cost per unit of electricity received.

[0347] The lower-level multi-scenario operation simulation model needs to meet multiple constraints constructed in steps S1 and S2 during operation to ensure the safe and stable operation of the power grid under each typical operation scenario.

[0348] Step S6: The upper and lower layers work together to iteratively solve for the optimal solution. The results of the lower layer are fed back to the upper layer, the optimization direction is dynamically adjusted, and the solution is iteratively solved until the optimal addressing and sizing scheme (i.e., the target planning scheme) that takes into account both economic efficiency and operational feasibility is obtained.

[0349] The upper-level site selection and capacity pre-planning model generates a set of candidate planning schemes and passes them to the lower level. The lower-level multi-scenario operation simulation model performs operation simulations based on typical scenarios under the given schemes, calculates the value of the second objective function representing the comprehensive operation benefits, and outputs new operation status data (e.g., first updated operation status data, second updated operation status data, etc.). The candidate planning schemes are verified based on the new operation status data to obtain the first verification result.

[0350] The second verification result is obtained by performing the following verification based on the actual power consumption data (such as the actual power consumption of wind power and the actual power consumption of photovoltaic power) in the new operating status data output by the lower-level multi-scenario operation simulation model.

[0351]

[0352]

[0353] in, , These represent the predicted available power output of wind power and solar power during time period t under operating scenario s.

[0354] Based on the new operational status data output by the lower-level multi-scenario operation simulation model, the following verification was performed to obtain the third verification result.

[0355]

[0356] in, The maximum allowable wind and solar curtailment rate.

[0357] Based on the line overload power in the new operating status data output by the lower-level multi-scenario operation simulation model, the following verification was performed, resulting in the fourth verification result.

[0358]

[0359] in, This is the preset line overload threshold.

[0360] The power received is verified based on the new operating status data output by the lower-level multi-scenario operation simulation model, resulting in the fifth verification result.

[0361]

[0362] in, These are the limits for the rate of increase / decrease of conventional generating units in the power grid.

[0363] If the second, third, fourth, and fifth verification results are all verified, it means that the first verification result is verified and the candidate planning scheme is feasible.

[0364] At this point, the new operating status data is further input into the upper-level addressing and sizing pre-planning model to obtain a new first objective function value. Based on the first and second iteration stopping conditions, it is determined whether to stop the iteration and obtain the target planning scheme.

[0365] The stopping condition for the first iteration is:

[0366]

[0367] in, , Let be the first objective function values ​​for the r-th iteration and the (r-1)-th iteration, respectively. For convergence accuracy.

[0368] The second iteration stopping condition is when the number of iterations reaches the maximum number of iterations. .

[0369] If any of the above-mentioned second, third, fourth, and fifth verification results fail, it indicates that the first verification result fails, and the candidate planning scheme is not feasible.

[0370] At this point, the parameters of the capacity configuration constraints for back-to-back flexible interconnect devices in the upper-layer site selection and capacity quantification pre-planning model and the target constraint set (such as the weighting coefficient of investment cost, capacity margin coefficient, penalty coefficient, and the node set corresponding to the candidate installation location) are adjusted to obtain an updated site selection and capacity quantification pre-planning model and an updated constraint set. Based on the initial operating status data and the updated constraint set, the updated site selection and capacity quantification pre-planning model is used to obtain an updated planning scheme. Based on the updated constraint set and the updated planning scheme, the lower-layer multi-scenario operation simulation model is used to obtain the second updated operating status data. The updated planning scheme is verified based on the second updated operating status data to obtain the sixth verification result. The updated planning scheme is iteratively optimized using the method of obtaining the target planning scheme based on the first verification result to obtain the target planning scheme.

[0371] If the first verification result is that the verification fails, the capacity configuration constraints of the back-to-back flexible interconnect device in the upper-layer site selection and capacity determination pre-planning model and the target constraint set shall be adjusted in the following way:

[0372] (1) Increase the weighting coefficient of investment cost in the upper-level site selection and sizing pre-planning model. ;

[0373] (2) Increase the capacity margin coefficient This will increase the lower limit of the rated capacity of VSC converter stations and improve capacity configuration;

[0374] (3) Add a penalty coefficient term to the first objective function;

[0375] (4) Screen out the candidate installation locations corresponding to nodes that have not passed the above verification, and narrow down the range of candidate installation locations.

[0376] Figure 3 This is a schematic diagram of an optional power grid planning result provided according to an embodiment, such as... Figure 3 As shown, the power grid comprises 34 zones, with back-to-back flexible interconnection devices installed between zones 21 and 33, zones 12 and 18, and zones 2 and 14.

[0377] The aforementioned method for site selection and capacity determination of VSC back-to-back flexible interconnection devices for multi-station and multi-regional urban power grids possesses high scalability. At the model level, it can be upgraded to a multi-timescale coordinated planning model (taking into account both day-ahead scheduling and long-term planning), or a robust optimization model and stochastic programming model that considers the uncertainty of renewable energy output. Furthermore, it can embed N-1 security constraints and transient voltage stability constraints to improve the reliability of the scheme. At the application level, it can overcome the limitations of specific voltage levels and regions, and be flexibly extended to 110kV distribution network regional interconnection, 500kV regional transmission network asynchronous interconnection, and source-load matching channel planning in areas with a high proportion of renewable energy penetration, so as to adapt to the differentiated operating characteristics of different power grids.

[0378] The above-mentioned optional implementation methods achieve at least the following effects: through the upper and lower layer collaborative iterative optimization mechanism, the planning scheme is continuously optimized under the premise of ensuring the operational feasibility of the planning scheme until the first objective function converges, thereby obtaining a globally optimal planning scheme that takes into account both investment economy and power grid operation safety; by dynamically adjusting the parameters of the upper layer location and capacity pre-planning model and the target constraint condition set when the lower layer verification fails, the optimization direction is guided to correct infeasible schemes, thereby achieving a globally optimal solution for the planning scheme that takes into account both economy and feasibility while ensuring that the back-to-back flexible interconnection device meets the operational safety boundaries of multiple scenarios.

[0379] It should be noted that the steps shown in the flowchart in 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 may be executed in a different order than that shown here.

[0380] This embodiment also provides a planning device for a back-to-back flexible interconnection device for a power grid. This device is used to implement the above embodiments and preferred embodiments, and details already described will not be repeated. As used below, the terms "module" and "device" can refer to a combination of software and / or hardware that performs a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0381] According to an embodiment, an apparatus embodiment for a planning method of implementing a back-to-back flexible interconnection device for a power grid is also provided. Figure 4 This is a schematic diagram of a planning device for a back-to-back flexible interconnection device for a power grid, provided according to an embodiment. Figure 4 As shown, the planning device for the back-to-back flexible interconnection device of the above-mentioned power grid includes a data acquisition module 402, a first determination module 404, a second determination module 406, a verification module 408, and a target planning scheme determination module 410. The device will be described below.

[0382] The data acquisition module 402 is used to acquire the initial operating status data of the power grid. The initial operating status data is acquired when the back-to-back flexible interconnection device is not installed in the power grid. The back-to-back flexible interconnection device includes two VSC converter stations.

[0383] The first determining module 404, connected to the data acquisition module 402, is used to determine candidate planning schemes for the power grid based on initial operating state data and a set of target constraints. The set of target constraints includes steady-state operating constraints of the power grid, operating characteristic constraints of back-to-back flexible interconnection devices, and location and capacity constraints of back-to-back flexible interconnection devices. The candidate planning schemes are used to indicate the installation locations of the multiple VSC converter stations included in the multiple back-to-back flexible interconnection devices planned to be installed in the power grid, as well as the rated capacities of the multiple VSC converter stations.

[0384] The second determining module 406 is connected to the first determining module 404 and is used to determine the first updated operating status data of the power grid based on the target constraint set and the candidate planning scheme. The first updated operating status data is obtained when the power grid has installed the back-to-back flexible interconnection device according to the candidate planning scheme and is in a typical operating scenario. The typical operating scenarios include the new energy fluctuation scenario and the load growth scenario.

[0385] The verification module 408, connected to the second determination module 406, is used to verify the candidate planning scheme based on the first updated running status data and obtain a first verification result, wherein the first verification result is used to indicate the operational feasibility of the candidate planning scheme.

[0386] The target planning scheme determination module 410 is connected to the verification module 408 and is used to obtain the target planning scheme of the power grid based on the first verification result.

[0387] In the planning device for a back-to-back flexible interconnection device of a power grid provided in the embodiment, by setting a data acquisition module 402, a first determination module 404, a second determination module 406, a verification module 408, and a target planning scheme determination module 410, the device aims to determine and verify candidate planning schemes of the power grid based on the initial operating state data and target constraint set of the power grid, and finally obtain the target planning scheme of the power grid based on the verification results. This achieves the technical effect of improving the accuracy of the target planning scheme determination results of the power grid, thereby solving the technical problem of inaccurate planning results of back-to-back flexible interconnection devices of power grids in related technologies.

[0388] It should be noted that the above modules can be implemented by software or hardware. For example, for the latter, it can be implemented in the following ways: the above modules can be located in the same processor; or the above modules can be located in different processors in any combination.

[0389] It should be noted that the data acquisition module 402, the first determination module 404, the second determination module 406, the verification module 408, and the target planning scheme determination module 410 correspond to steps S102 to S110 in the embodiments. The instances and application scenarios implemented by the above modules and corresponding steps are the same, but are not limited to the content disclosed in the above embodiments. It should be noted that the above modules, as part of the device, can run in a computer terminal.

[0390] It should be noted that the optional or preferred implementation methods of this embodiment can be found in the relevant descriptions in the embodiments, and will not be repeated here.

[0391] The planning device for the back-to-back flexible interconnection device of the aforementioned power grid may also include a processor and a memory. The data acquisition module 402, the first determination module 404, the second determination module 406, the verification module 408, the target planning scheme determination module 410, etc. are all stored in the memory as program units, and the processor executes the above-mentioned program units stored in the memory to realize the corresponding functions.

[0392] The processor contains a core that retrieves the corresponding program unit from memory. One or more cores may be configured. Memory may include non-persistent memory in computer-readable media, random access memory (RAM), and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory includes at least one memory chip.

[0393] The embodiment provides a non-volatile storage medium storing a program that, when executed by a processor, implements a planning method for back-to-back flexible interconnection devices of a power grid.

[0394] The embodiment provides an electronic device, Figure 5 This is a structural diagram of an electronic device provided according to an embodiment of this application. For example... Figure 5 As shown, the electronic device may include: one or more ( Figure 5 (Only one is shown) a processor 502, a memory 504, a memory controller, and a peripheral interface, wherein the peripheral interface is connected to an RF module, an audio module, and a display. The electronic device includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it performs the following steps: acquiring initial operating state data of the power grid, which is acquired before back-to-back flexible interconnection devices are installed in the power grid, the back-to-back flexible interconnection devices including two VSC converter stations; based on the initial operating state data and a set of target constraints, determining candidate planning schemes for the power grid, wherein the set of target constraints includes steady-state operation constraints of the power grid, operating characteristic constraints of the back-to-back flexible interconnection devices, and location and capacity constraints of the back-to-back flexible interconnection devices, and the candidate planning schemes are used to indicate multiple back-to-back flexible interconnection devices planned to be installed in the power grid. This includes the installation locations of multiple VSC converter stations and their respective rated capacities. Based on the target constraint set and candidate planning schemes, the first updated operating status data of the power grid is determined. This first updated operating status data is obtained when the power grid has installed back-to-back flexible interconnection devices according to the candidate planning schemes and is operating under typical scenarios, including renewable energy fluctuation scenarios and load growth scenarios. Based on the first updated operating status data, the candidate planning schemes are verified to obtain the first verification result, which indicates the operational feasibility of the candidate planning schemes. Based on the first verification result, the target planning scheme for the power grid is obtained. The equipment mentioned in this paper can be servers, PCs, etc.

[0395] A computer program product is also provided, which, when executed on a data processing device, is suitable for executing an initialization program with the following method steps: acquiring initial operating state data of the power grid, the initial operating state data being acquired when no back-to-back flexible interconnection devices are installed in the power grid, the back-to-back flexible interconnection devices including two VSC converter stations; based on the initial operating state data and a set of target constraints, determining candidate planning schemes for the power grid, wherein the set of target constraints includes steady-state operation constraints of the power grid, operating characteristic constraints of the back-to-back flexible interconnection devices, and location and capacity constraints of the back-to-back flexible interconnection devices, and the candidate planning schemes are used to indicate the multiple back-to-back flexible interconnection devices planned to be installed in the power grid. The installation locations and rated capacities of multiple VSC converter stations are determined. Based on the target constraint set and candidate planning schemes, the first updated operating status data of the power grid is determined. This first updated operating status data is obtained when the power grid has installed back-to-back flexible interconnection devices according to the candidate planning schemes and is in typical operating scenarios, including renewable energy fluctuation scenarios and load growth scenarios. Based on the first updated operating status data, the candidate planning schemes are verified to obtain the first verification result, which indicates the operational feasibility of the candidate planning schemes. Based on the first verification result, the target planning scheme of the power grid is obtained.

[0396] Those skilled in the art will understand that the embodiments can be provided as methods, systems, or computer program products. Therefore, they can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, they can take the form of computer program products implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0397] The description is based on flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments. It will be understood that each block of the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, produce a machine for implementing the flowcharts and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0398] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0399] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0400] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0401] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0402] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0403] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0404] Those skilled in the art will understand that the embodiments can be provided as methods, systems, or computer program products. Therefore, they can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, they can take the form of computer program products implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0405] The above are merely embodiments and are not intended to limit the scope of the invention. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of the claims.

Claims

1. A planning method for a back-to-back flexible interconnection device for a power grid, characterized in that, include: Acquire initial operating status data of the power grid, which is acquired when the power grid has not installed back-to-back flexible interconnection devices, which include two VSC converter stations; Based on the initial operating status data and the target constraint set, candidate planning schemes for the power grid are determined. The target constraint set includes the steady-state operation constraints of the power grid, the operating characteristic constraints of the back-to-back flexible interconnection devices, and the location and capacity constraints of the back-to-back flexible interconnection devices. The candidate planning schemes are used to indicate the installation locations of the multiple VSC converter stations included in the multiple back-to-back flexible interconnection devices planned to be installed in the power grid, as well as the rated capacities of the multiple VSC converter stations. Based on the target constraint set and the candidate planning scheme, the first updated operating status data of the power grid is determined. The first updated operating status data is obtained when the power grid has installed back-to-back flexible interconnection devices according to the candidate planning scheme and is in a typical operating scenario. The typical operating scenario includes new energy fluctuation scenario and load growth scenario. Based on the first updated running status data, the candidate planning scheme is verified to obtain a first verification result, wherein the first verification result is used to indicate the operational feasibility of the candidate planning scheme; Based on the first verification result, the target planning scheme for the power grid is obtained.

2. The method according to claim 1, characterized in that, Before determining the candidate planning scheme for the power grid based on the initial operating state data and the target constraint set, the method further includes: Construct the initial set of constraints; The constraints that do not satisfy convexity in the initial constraint set are relaxed to obtain the target constraint set, wherein convexity means that the feasible region defined by the constraint is a convex set.

3. The method according to claim 1, characterized in that, The step of determining candidate planning schemes for the power grid based on the initial operating state data and the target constraint set includes: Based on the initial operating status data and the target constraint set, the candidate planning scheme is obtained by adopting the upper-level site selection and capacity determination pre-planning model. The upper-level site selection and capacity determination pre-planning model includes a first objective function and a first constraint. The first objective function aims to minimize investment cost, regional imbalance, and power supply security risk. The first constraint includes investment budget constraint, paired installation constraint, and installation location screening constraint. The first objective function for: in, To normalize investment costs, For partition imbalance, For power supply safety redundancy, The penalty coefficient is... The weighting coefficient for investment costs. The weighting coefficients for partition imbalance. The weighting coefficient for power supply safety redundancy.

4. The method according to claim 1, characterized in that, The step of determining the first updated operating status data of the power grid based on the target constraint set and the candidate planning scheme includes: Based on the candidate planning scheme and the target constraint set, the first updated operating status data is obtained by using a lower-level multi-scenario operation simulation model. The lower-level multi-scenario operation simulation model includes a second objective function, which is used to maximize the comprehensive operating benefits of the power grid under typical operating scenarios. Second objective function for: in, This is a collection of typical operating scenarios. Let be the probability of scenario s occurring. For time period sets, This represents the actual wind power absorption capacity during time period t under operating scenario s. This represents the actual photovoltaic power absorbed during time period t under operating scenario s. This represents the amount of wind and solar power curtailed during time period t under operating scenario s. The line overload power during time period t under operating scenario s. This refers to the power received by the power grid from the back-to-back flexible interconnection device during time period t under operating scenario s. The unit wind power price for time period t under operating scenario s. The unit photovoltaic electricity price for time period t under operating scenario s. The penalty coefficient for wind and solar power curtailment. This is the line overload penalty coefficient. Cost per unit of electricity received.

5. The method according to claim 1, characterized in that, The step of verifying the candidate planning scheme based on the first updated running status data to obtain a first verification result includes: Based on the actual power absorption data in the first updated operating status data, a second verification result is obtained; Based on the wind and solar power curtailment in the first updated operating status data, a third verification result is obtained; Based on the line overload power in the first updated operating status data, the fourth verification result is obtained; Based on the power received in the first updated operating status data, the fifth verification result is obtained; If the second verification result, the third verification result, the fourth verification result, and the fifth verification result are all verified successfully, then the first verification result is determined to be verified successfully. If any of the second, third, fourth, and fifth verification results fails, the first verification result is determined to be a verification failure.

6. The method according to claim 1, characterized in that, The step of obtaining the target planning scheme for the power grid based on the first verification result includes: If the first verification result is successful, based on the first updated operating status data, the candidate planning scheme is iteratively optimized using the upper-layer location and capacity pre-planning model and the lower-layer multi-scenario operation simulation model to obtain the target planning scheme.

7. The method according to any one of claims 1 to 6, characterized in that, The step of obtaining the target planning scheme for the power grid based on the first verification result includes: If the first verification result is that the verification fails, the parameters of the upper-level site selection and capacity determination pre-planning model and the back-to-back flexible interconnect device capacity configuration constraints in the target constraint set are adjusted to obtain the updated site selection and capacity determination pre-planning model and the updated constraint set. Based on the initial operating status data and the set of update constraints, the update planning scheme is obtained by using the update site selection and capacity pre-planning model. Based on the set of update constraints and the update planning scheme, a lower-level multi-scenario operation simulation model is used to obtain the second update operation status data. Based on the second update operation status data, the update planning scheme is verified to obtain the sixth verification result; The target planning scheme is obtained by using the method described above, based on the sixth verification result.

8. A planning device for a back-to-back flexible interconnection device of a power grid, characterized in that, include: The data acquisition module is used to acquire the initial operating status data of the power grid. The initial operating status data is acquired when the power grid has not installed back-to-back flexible interconnection devices, which include two VSC converter stations. The first determining module is used to determine candidate planning schemes for the power grid based on the initial operating state data and the target constraint set. The target constraint set includes the steady-state operation constraints of the power grid, the operating characteristic constraints of the back-to-back flexible interconnection devices, and the location and capacity constraints of the back-to-back flexible interconnection devices. The candidate planning scheme is used to indicate the installation locations of the multiple VSC converter stations included in the multiple back-to-back flexible interconnection devices planned to be installed in the power grid, and the rated capacities of the multiple VSC converter stations. The second determining module is used to determine the first updated operating status data of the power grid based on the target constraint set and the candidate planning scheme. The first updated operating status data is obtained when the power grid has installed the back-to-back flexible interconnection device according to the candidate planning scheme and is in a typical operating scenario. The typical operating scenario includes the new energy fluctuation scenario and the load growth scenario. The verification module is used to verify the candidate planning scheme based on the first updated running status data and obtain a first verification result, wherein the first verification result is used to indicate the operational feasibility of the candidate planning scheme. The target planning scheme determination module is used to obtain the target planning scheme of the power grid based on the first verification result.

9. A non-volatile storage medium, characterized in that, The non-volatile storage medium stores multiple instructions adapted for loading and execution by a processor of the planning method for a back-to-back flexible interconnection device of a power grid as described in any one of claims 1 to 7.

10. An electronic device, characterized in that, include: One or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the planning method for a back-to-back flexible interconnection device of a power grid as described in any one of claims 1 to 7.

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