SVC (static var compensator) new energy short-circuit ratio margin evaluation method, system, equipment and medium

Abstract

The invention relates to the technical field of new energy grid-connected system stability analysis, in particular to an SVC new energy short-circuit ratio margin assessment method, system equipment and a medium, and aims to accurately correct a real-time voltage support strength assessment model of a new energy access point by dynamically integrating SVC reactive compensation capacity into a short-circuit ratio calculation process. The defect of system strength misjudgment caused by neglecting reactive compensation in a traditional method is overcome; analyzing a static voltage stability limit based on the maximum transmission power of the new energy, and accurately defining a critical short-circuit ratio as an instability boundary threshold value; a margin index is calculated through a difference value between a short-circuit ratio and a critical short-circuit ratio, the safety redundancy of the system is directly quantified, and a single-station independent access and multi-station strong coupling scene is compatible with the positive and negative characteristics of a unified margin criterion, so that the prevention and control capability on the voltage collapse risk of a high-proportion new energy power grid is remarkably improved; and a grounding stability decision basis is provided for new energy station planning and site selection, SVC reactive compensation configuration and power grid operation scheduling.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of grid-connected system stability analysis of new energy, and particularly relates to an SVC new energy short-circuit ratio margin evaluation method, a system device and a medium. BACKGROUND

[0002] With the gradual evolution of the power system into a "double-high" system containing high proportions of new energy and high proportions of power electronic devices, the installed capacity of new energy continues to rise, and the proportion of traditional thermal power units is reduced, which has profoundly changed the composition and operation mode of the power system, and the short-circuit current control margin of equipment at each voltage level is thus increasingly strained.

[0003] The installed capacity and power generation proportion of new energy represented by photovoltaic continue to rise. The operation of large-capacity direct current and photovoltaic requires the AC power grid to have sufficient voltage support strength, while facing problems such as insufficient dynamic reactive power support capability of tie lines and insufficient reactive power support capability under fault modes. In view of such problems, the access of SVC reactive power compensation devices can properly solve the problems and achieve good results. Short-circuit ratio is an important indicator for quantifying the strength of the receiving end power grid system of new energy centralized grid connection, and the critical short-circuit ratio is the short-circuit ratio corresponding to the critical stable state of the system. Comparing the relative size of the short-circuit ratio and the critical short-circuit ratio can evaluate the stability of the system under the rated operating state. At present, most related researches focus on the short-circuit ratio evaluation method of multi-infeed transmission systems, while ignoring the influence of reactive power compensation devices.

[0004] In view of the above problems, the short-circuit ratio margin index proposed by the SVC reactive power compensation device can quantitatively evaluate the safety and stability of the new energy grid-connected system, and provide a reference for maintaining the planning and operation control of the new energy grid-connected power grid. SUMMARY

[0005] In view of the above existing problems, the present application is proposed.

[0006] Therefore, the present application provides an SVC new energy short-circuit ratio margin evaluation method and system, which determines the short-circuit ratio margin control by calculating the short-circuit ratio and the critical short-circuit ratio of the new energy station, and judges the stability of the new energy single-infeed system and the new energy multi-infeed system containing the SVC reactive power compensation device.

[0007] To solve the above technical problems, the present application provides the following technical solutions:

[0008] In a first aspect, the present application provides an SVC new energy short-circuit ratio margin evaluation method, comprising:

[0009] Based on the short-circuit capacity and compensation capacity of the new energy grid connection, the short-circuit ratio of the voltage support strength is calculated;

[0010] Calculate the critical short-circuit ratio corresponding to the stable state based on the transmission capacity of new energy;

[0011] Calculate the short-circuit ratio margin by the difference between the short-circuit ratio and the critical short-circuit ratio, and evaluate the safety margin of new energy.

[0012] As a preferred scheme of the SVC new energy short-circuit ratio margin evaluation method, the short-circuit ratio based on the short-circuit capacity and compensation capacity of new energy grid connection is calculated, the distortion of intensity is solved by fusing compensation capacity correction capacity model, including:

[0013] Integrate short-circuit capacity and compensation capacity to quantify the voltage support strength of new energy station grid connection;

[0014] Calculate the coupling effect of multiple stations, and obtain the interaction strength of new energy multiple station grid connection through conversion factor expansion calculation;

[0015] Based on the calculation result, the short-circuit ratio index representing the strength is output.

[0016] As a preferred scheme of the SVC new energy short-circuit ratio margin evaluation method, the critical short-circuit ratio corresponding to the stable state is calculated based on the transmission capacity of new energy, the static voltage stability limit is analyzed, and the instability boundary threshold is located, including:

[0017] Deduce the static voltage stability point through the transmission capacity of new energy;

[0018] Establish the correlation model of short-circuit ratio and voltage stability threshold to determine the critical short-circuit ratio of stable state;

[0019] Take the critical short-circuit ratio as the boundary threshold of instability to complete the stability judgment.

[0020] As a preferred scheme of the SVC new energy short-circuit ratio margin evaluation method, the unified margin criterion is constructed, the short-circuit ratio margin is calculated by the difference between the short-circuit ratio and the critical short-circuit ratio, and the safety margin of new energy is evaluated, including:

[0021] Generate the short-circuit ratio margin index quantifying the stable boundary distance through the difference operation between the short-circuit ratio and the critical short-circuit ratio;

[0022] Based on the short-circuit ratio margin value, map the stable state, unstable state and safety degree of new energy grid connection system;

[0023] Compatible stability judgment basis, realize the stability evaluation of new energy stations of different scales through unified margin criterion.

[0024] As a preferred scheme of the SVC new energy short-circuit ratio margin evaluation method, the difference operation between the short-circuit ratio and the critical short-circuit ratio comprises:

[0025] The stability of the system is determined by comparing the short-circuit ratio with the critical short-circuit ratio.

[0026] When the critical stable state is not reached, there is a difference interval between the short-circuit ratio and the critical short-circuit ratio.

[0027] The difference interval represents the safety margin.

[0028] The beneficial effects of the preferred technical scheme are: the difference operation design converts the abstract stability problem into intuitive numerical comparison, significantly improving the recognition efficiency of the system safety state. By comparing the actual short-circuit ratio with the critical short-circuit ratio in real time, it can be clearly distinguished whether the system is in a stable operation interval or is close to a risk zone of instability, providing clear stability state demarcation basis for the operating personnel. When the system has not reached the critical point, the positive margin interval formed by the difference between the two directly quantifies the safety boundary depth of the system that can withstand disturbances at present, and the greater the value is, the stronger the system resilience is. The operation mechanism is naturally adapted to single station and multi-station scenarios, and the stability is determined by the positive and negative signs of the margin, and the safety degree is quantified by the margin value, which not only simplifies the evaluation process, but also provides a key decision basis for reactive power compensation configuration and operation strategy adjustment.

[0029] As a preferred scheme of the SVC new energy short-circuit ratio margin evaluation method, the compatibility stability judgment basis comprises:

[0030] The reactive power interaction effect between adjacent new energy stations is dynamically quantified by the complex power conversion factor, and the synergistic correction of the SVC compensation capacity on the voltage support strength of multiple nodes is integrated in the short-circuit ratio calculation, eliminating the error of the single-station evaluation model to the interconnection;

[0031] A unified stability criterion is established with the positive and negative values of the short-circuit ratio margin as the core.

[0032] The beneficial effects of this preferred technical solution are as follows: By introducing a complex power conversion factor to dynamically quantify the reactive power interaction effect between adjacent renewable energy power plants, the coupling effect of multiple nodes is accurately captured, solving the evaluation error problem of traditional single-power plant models in interconnected scenarios; at the same time, the synergistic correction effect of SVC compensation capacity on voltage support strength is integrated, significantly improving the accuracy of multi-power plant system strength assessment. Finally, a unified stability criterion with the positive and negative values ​​of short-circuit ratio margin as the core is established, enabling both single-infeed and multi-infeed systems to directly determine the stable state through the sign of the margin value, and quantifying the degree of safety based on the margin size. This achieves standardization and comparability of stability assessment methods for renewable energy power plants of different scales, providing a universally applicable, intuitive, and reliable decision-making basis for power grid planning and reactive power allocation.

[0033] As a preferred embodiment of the SVC (Short-Circuit Ratio Margin) assessment method for new energy sources according to the present invention, the stability judgment criteria include:

[0034] Stability criteria for single-infeed and multi-infeed of new energy sources;

[0035] Among them, the stability criteria for a single new energy power station include that when the margin value of a single new energy power station is greater than zero, it is stable; when the margin value of a single new energy power station is less than zero, it is unstable.

[0036] The stability criteria for multiple feed-in sources of renewable energy include: when the margin value of multiple renewable energy power plants is greater than zero, the plant is considered stable; when the margin value of multiple renewable energy power plants is less than zero, the plant is considered unstable.

[0037] The beneficial effects of this preferred technical solution are as follows: By clearly defining the stability criteria for single-infeed and multi-infeed renewable energy systems, and uniformly adopting the sign of the short-circuit ratio margin value as the core judgment standard, the intuitiveness and operability of system safety assessment are significantly improved. This method allows operation and maintenance personnel to quickly identify the system state without relying on complex calculations—a single power station with a margin value greater than zero is judged as a stable operating state, and one with a margin value less than zero is judged as a state at risk of instability; multi-power station systems also achieve consistent stability judgment based on the sign of their margin values. This standardized criterion effectively solves the problem of fragmented logic in the stability assessment of renewable energy power stations of different scales in traditional methods, greatly simplifies the power grid safety monitoring process, and provides clear safety boundary guidance for the planning and configuration of reactive power compensation capacity for renewable energy power stations, thereby strengthening the power system's anti-disturbance capability and operational reliability under high-proportion renewable energy access.

[0038] Secondly, the present invention provides an SVC (Supply-Voltage Capacity) renewable energy short-circuit ratio margin assessment system, comprising:

[0039] The strength quantification module calculates the short-circuit ratio of voltage support strength based on the short-circuit capacity and compensation capacity of new energy grid connection, and solves the strength distortion problem by integrating the compensation capacity to correct the capacity model.

[0040] The critical determination module, based on the transmission capacity of new energy sources, calculates the critical short-circuit ratio corresponding to the stable state, analyzes the static voltage stability limit, and locates the instability boundary threshold.

[0041] The margin assessment module constructs a unified margin criterion and calculates the short-circuit ratio margin by the difference between the short-circuit ratio and the critical short-circuit ratio to assess the safety margin of new energy vehicles.

[0042] Thirdly, the present invention provides an electronic device, comprising:

[0043] Memory and processor;

[0044] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of an SVC (Short-Circuit Margin Assessment) method for evaluating the short-circuit ratio margin of new energy sources.

[0045] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the SVC renewable energy short-circuit ratio margin assessment method.

[0046] Compared with existing technologies, the beneficial effects of this invention are as follows: By dynamically integrating the reactive power compensation capacity of the SVC into the short-circuit ratio calculation, this invention accurately quantifies the real-time voltage support strength of the power grid under high-proportion renewable energy access, solving the problem of misjudgment of system strength caused by neglecting reactive power compensation in traditional methods; by determining the critical short-circuit ratio based on the maximum transmission power, it clarifies the boundary threshold of static voltage instability in renewable energy grid-connected systems, providing an accurate early warning benchmark for safe grid operation; by directly mapping the system safety redundancy through the short-circuit ratio margin difference, and by using a unified criterion compatible with independent access of single power plants and strongly coupled scenarios of multiple power plants, it significantly improves the ability to prevent and control the voltage collapse risk of "high-voltage and high-efficiency" power systems, providing a feasible stability decision-making basis for renewable energy power plant planning and site selection, SVC capacity configuration, and operation scheduling. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a schematic diagram of the overall process of an SVC (Short Circuit Ratio Margin) assessment method for new energy sources according to an embodiment of the present invention.

[0049] Figure 2This is a schematic diagram of a multi-station grid-connected new energy system with an SVC reactive power compensation device, which is an embodiment of the SVC new energy short-circuit ratio margin assessment method described in this invention.

[0050] Figure 3 This diagram illustrates the impact of reactive power compensation from SVC access on various parameters of the short-circuit ratio in an SVC renewable energy short-circuit ratio margin assessment method according to an embodiment of the present invention.

[0051] Figure 4 This is a graph showing the short-circuit ratio related indicators of a multi-infeed system according to an embodiment of the SVC (Short-Circuit Ratio Margin) renewable energy short-circuit ratio assessment method. Detailed Implementation

[0052] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0053] Example 1, referring to Figure 1 As an embodiment of the present invention, a method for evaluating the short-circuit ratio margin of SVC (Supply-Voltage Capacity) renewable energy sources is provided, comprising:

[0054] S1: Based on the short-circuit capacity and compensation capacity of new energy grid connection, calculate the short-circuit ratio of voltage support strength, and correct the capacity model by integrating compensation capacity to solve the strength distortion;

[0055] S2: Based on the new energy transmission capacity, calculate the critical short-circuit ratio corresponding to the steady state, analyze the static voltage stability limit, and locate the instability boundary threshold.

[0056] S3: Construct a unified margin criterion, calculate the short-circuit ratio margin by the difference between the short-circuit ratio and the critical short-circuit ratio, and evaluate the safety margin of new energy.

[0057] It should be noted that in "dual-high" power systems containing a high proportion of new energy and power electronic equipment, the traditional short-circuit ratio assessment method ignores the dynamic impact of reactive power compensation devices on voltage support strength, leading to misjudgment of system strength, ambiguity of critical stability boundaries, and inability to quantify the safety margin in scenarios with multiple new energy power plants coupled together, which seriously restricts the accuracy of power grid planning and operation control.

[0058] Therefore, in response to the aforementioned problems of insufficient dynamic reactive power support capacity, increased risk of voltage instability under fault conditions, and lack of assessment of the interactive impact of multi-infeed systems, a closed-loop mapping mechanism of reactive power compensation-system strength-stability boundary is systematically constructed through steps S1-S3. This achieves a full-chain technological breakthrough from accurate quantification of grid strength and dynamic early warning of collapse threshold to intuitive assessment of safety margin, providing direct and effective decision support for the site selection of new energy power plants, SVC capacity configuration, and the formulation of grid security defense strategies.

[0059] Example 2, refer to Figure 2 As an embodiment of the present invention, based on the above embodiment, a method for evaluating the short-circuit ratio margin of SVC new energy is provided.

[0060] In this embodiment of the application, step S1 calculates the short-circuit ratio of voltage support strength based on the short-circuit capacity and compensation capacity of the new energy grid-connected system. By integrating the compensation capacity to correct the capacity model, strength distortion is resolved. In the new energy power station access system, based on the short-circuit capacity of the new energy grid-connected bus and the SVC reactive power compensation capacity, the short-circuit ratio of multiple new energy power stations containing SVC reactive power compensation devices is calculated. Figure 2 As shown, it includes:

[0061] The reactive power compensation capacity of SVC is expressed as:

[0062] Q s,i =U 2 B

[0063] Among them, Q s,i U is the reactive power compensation capacity; U is the reactive power compensation point voltage; B is the capacitance to ground.

[0064] Short-circuit ratio of a single power station for new energy sources including SVC reactive power compensation device:

[0065] The short-circuit capacity of the grid-connected bus of a new energy power station with SVC reactive power compensation device is expressed as follows:

[0066]

[0067] Among them, U N Nominal voltage at the grid connection point; E eq,i Z is the equivalent potential at grid connection point i; ii The self-impedance of the grid-connected busbar of the new energy power station;

[0068] The short-circuit ratio of a single renewable energy power station with an SVC reactive power compensation device is expressed as follows:

[0069]

[0070] Among them, S w,iP represents the short-circuit capacity of the grid-connected bus of a new energy power station with SVC reactive power compensation device. N,i Rated capacity of new energy at the grid connection point; SCR i The short-circuit ratio of a single renewable energy power station with SVC reactive power compensation device is used to assess the voltage support strength of the renewable energy grid-connected system by measuring the relative strength of the system and renewable energy.

[0071] The short-circuit capacity of the grid-connected bus of a renewable energy power station with SVC reactive power compensation device is expressed as follows:

[0072]

[0073] Where * represents the conjugate operation; The rated voltage of the grid-connected busbar of the new energy power station; This refers to the short-circuit current at the grid-connected bus of the new energy power station. For the grid-connected bus voltage of the new energy power station; Z ii The self-impedance of the grid-connected busbar of the new energy power station;

[0074] For multi-infeed DC networks, the short-circuit ratio (SCR) of a single renewable energy power station is... i Based on this, a short-circuit ratio MRSCR for multiple power plants with SVC reactive power compensation devices is proposed. i The voltage support strength of a multi-station renewable energy system is assessed and expressed as follows:

[0075]

[0076] Among them, S s,i S s,j The actual apparent power of new energy injected into the i-th and j-th new energy grid-connected bus nodes; The complex power conversion factor between new energy grid-connected bus i and j;

[0077] Based on the short-circuit capacity of the grid-connected bus of the new energy power station, the above formula can be transformed into:

[0078]

[0079] Among them; Z ij The equivalent impedance between the grid-connected busbars of new energy power station i and new energy power station j; Inject AC current into new energy power stations i and j.

[0080] In an optional implementation, the short-circuit ratio for calculating voltage support strength in step S1 can also be dynamically adjusted by combining the actual power output fluctuations of the renewable energy power station, and the short-circuit capacity calculation can be updated based on real-time monitored voltage data. For example, in a wind farm integration scenario, when wind speed changes lead to an increase in renewable energy output, the system voltage may fluctuate. In this case, by collecting grid connection point voltage and renewable energy output data in real time, the SVC compensation capacity can be dynamically optimized, and then the short-circuit capacity and short-circuit ratio can be recalculated. This not only more accurately reflects the voltage support strength of the system under dynamic operating conditions, but also prevents voltage instability.

[0081] In another optional implementation, the short-circuit ratio for calculating voltage support strength in step S1 can also be improved by introducing an impedance coordination mechanism between feed points, optimizing the complex power conversion factor in a multi-station renewable energy system, and improving the accuracy of the short-circuit ratio. Specifically, in a photovoltaic power station cluster, when the feed points are close together, the calculation of the short-circuit ratio of multiple stations can be dynamically adjusted and optimized by measuring the equivalent impedance between renewable energy stations online; this effectively quantifies the interactive influence of multiple feed points and avoids optimistic bias in the planning scheme.

[0082] In this embodiment of the application, step S2 calculates the critical short-circuit ratio corresponding to the steady state based on the new energy transmission capacity, analyzes the static voltage stability limit, and locates the instability boundary threshold. It also calculates the critical short-circuit ratio of the new energy power station containing the SVC reactive power compensation device based on the maximum transmission power of the new energy system.

[0083] The derivation of the maximum transmission power of a grid-connected new energy system containing SVCs yields a quadratic equation related to the grid connection point voltage, which can be expressed as:

[0084] U 4 β-U 2 [E 2 +2(PR+QX-γ)]+S 2 Z 2 =0

[0085]

[0086] Where, λ s μ s λ is the calculation factor. S =(PR+QX-QBZ) 2 ) / E 2 μ s =(PX-QR-PBZ) 2 ) / E 2 γ and β are calculation factors related to reactive power compensation. γ = QBZ 2 β=1-2BX+B 2 Z 2 ;

[0087] According to Δ s =0, the maximum transmission power P of the new energy grid-connected system containing SVC is 0. Smax Represented as:

[0088]

[0089] Where R is the resistance at the grid-connected bus of the new energy power station, E is the potential at the grid-connected bus, Q is the reactive power at the grid-connected node of the new energy power station, and X is the reactance at the grid-connected bus of the new energy power station.

[0090] New energy power station grid-connected short-circuit capacity S ac Represented as:

[0091]

[0092] in, Z is the rated AC voltage at the DC feed point; Z is the equivalent reactance of the AC system.

[0093] The critical short-circuit ratio establishes the relationship between the short-circuit ratio and static voltage stability, using the maximum transmission power as the criterion for static voltage stability. As the transmission power increases, the operating point transitions from the upper half to the lower half of the PV curve, reaching the maximum transmission power at the inflection point, at which point the system is critically stable. At this point, the short-circuit ratio is the critical short-circuit ratio. The critical short-circuit ratio of the new energy power station i is determined by the CSCR (Continuous Voltage Regulator). i Represented as:

[0094]

[0095] Where k is an imaginary number.

[0096] In an optional implementation, the critical short-circuit ratio calculated in step S2 corresponding to the steady state can also be optimized by introducing dynamic reactive power compensation response characteristics. Specifically, considering the actual reactive power regulation rate and delay characteristics of the SVC device during the system transient process, and combining the power output fluctuation data of new energy power plants (such as minute-level fluctuations in photovoltaic power or turbulent fluctuations in wind turbines), a time-varying maximum transmission power model is established. By collecting the correlation between the voltage drop rate at the grid connection point and the reactive power output change rate of the SVC in real time, the equivalent reactance parameters in the calculation of the critical short-circuit ratio are dynamically corrected, so that the critical short-circuit ratio is closer to the dynamic influence of the SVC on the system voltage support strength in actual operation.

[0097] In another optional implementation, the critical short-circuit ratio corresponding to the steady state in step S2 can also be calculated by integrating multiple feed-in coupling factors. For scenarios where adjacent renewable energy power plants share SVC reactive power resources (such as multiple photovoltaic power plants connected to the same SVC centralized compensation point), when calculating the critical short-circuit ratio of the i-th power plant, a coupling coefficient (reflecting the sensitivity of the reactive power change of power plant j to the voltage of power plant i) is introduced. The original single-point maximum transmission power equation is extended to a matrix form to quantitatively evaluate the collaborative allocation effect of SVC reactive power resources among multiple power plants, avoiding the problem of optimistic estimation of the critical short-circuit ratio caused by reactive power competition among neighboring power plants.

[0098] In this application embodiment, step S3 establishes a unified margin criterion, calculates the short-circuit ratio margin by the difference between the short-circuit ratio and the critical short-circuit ratio, and evaluates the safety margin of renewable energy. The short-circuit ratio margin of renewable energy power plants containing SVC reactive power compensation devices is calculated based on the difference between the short-circuit ratio and the critical short-circuit ratio to quantitatively evaluate the stability of the renewable energy feed-in system, including:

[0099] Short-circuit ratio margin η of a new energy single power station with SVC reactive power compensation device SCR Represented as:

[0100]

[0101] Among them, Q i P represents the equivalent reactive power transmitted from new energy sources to the AC system. N,i The rated capacity of new energy at the grid connection point;

[0102] By comparing the system short-circuit ratio with the critical short-circuit ratio, the stability of the system can be determined. Before the system reaches critical stability, there is a certain difference range between the system short-circuit ratio and the critical short-circuit ratio. This difference range represents the safety margin of the system. The quantitative index of the safety margin of a single new energy power station is expressed through η. SCR express;

[0103] The stability criterion for a single-feedback new energy system is expressed as follows:

[0104] When SCR i <CSCR i , that is, η SCR When the value is less than 0, the new energy grid-connected system is in an unstable state, and the stability margin η is less than 0. SCR The larger the value, the less stable the system.

[0105] When SCR i >CSCR i , that is, η SCR When the value is greater than 0, the new energy grid-connected system is in a stable state, and the stability margin η is [value missing]. SCRThe larger the value, the more stable the system.

[0106] The short-circuit ratio margin of multiple new energy power stations connected to the grid is expressed as follows:

[0107]

[0108] in, The short-circuit capacity of the grid-connected bus of the new energy power station is defined. By comparing the system short-circuit ratio with the critical short-circuit ratio, the stability of the system is determined. Before the system reaches critical stability, there is a certain difference range between the system short-circuit ratio and the critical short-circuit ratio. This difference range represents the safety margin of the system. The safety margin quantification index for multiple new energy power stations is expressed through η. MRSCR express;

[0109] The stability criterion for a new energy multi-infeed system with SVC reactive power compensation device is expressed as follows:

[0110] When MRSCR i <CSCR i , that is, η MRSCR When the value is less than 0, the new energy power station access system is in an unstable state, and the stability margin η is less than 0. MRSCR The larger the value, the less stable the system.

[0111] When MRSCR i >CSCR i , that is, η MRSCR When the value is greater than 0, the new energy power station access system is in a stable state, and the stability margin η is [value missing]. MRSCR The larger the value, the more stable the system.

[0112] It should be noted that by calculating the short-circuit ratio margin of new energy power plants with SVC reactive power compensation, the abstract static voltage stability problem is transformed into an intuitive numerical comparison, significantly improving the efficiency of safety status identification: real-time comparison of the actual short-circuit ratio and the critical short-circuit ratio can clearly distinguish between the stable operating range and the instability risk zone, providing clear criteria for operators; the positive margin range directly quantifies the system's disturbance rejection capability, with a larger margin value indicating stronger resilience; by introducing a complex power conversion factor to dynamically quantify the reactive power interaction effect of multiple power plants (such as in symmetrical scenarios with multiple infeed impedances), and by integrating SVC compensation capacity to collaboratively correct voltage support strength, the influence of node coupling is accurately captured, solving the evaluation error of traditional single-power plant models and improving the accuracy of multi-power plant evaluation; a unified stability criterion with the positive and negative margin values ​​as the core is established to achieve standardization of evaluation methods and comparability of results for power plants of different scales.

[0113] In an optional implementation, the short-circuit ratio margin calculated in step S3 by the difference between the short-circuit ratio and the critical short-circuit ratio can also be dynamically corrected by combining the actual operating conditions of the new energy power station. Specifically, when calculating the short-circuit ratio margin of a single new energy power station, the voltage fluctuation rate of the grid connection point and the response time of the reactive power compensation device collected in real time are introduced as correction factors. When the voltage fluctuation rate is detected to be >5% and the response time of the reactive power compensation device is detected to be >20ms, the critical short-circuit ratio is multiplied by a safety factor to obtain the correction margin. By dynamically increasing the critical short-circuit ratio threshold, the adaptability to voltage transient processes is enhanced.

[0114] In another optional implementation, the short-circuit ratio margin calculated in step S3 by the difference between the short-circuit ratio and the critical short-circuit ratio can also be achieved by integrating a multi-timescale evaluation framework. For the short-circuit ratio margin of multiple new energy power plants, in addition to the conventional steady-state calculation, a short-time margin assessment of 0.5s after the fault is added. By utilizing the supporting characteristics of the reactive power compensation capacity of the SVC during the fault, the apparent power is replaced with the actual output upper limit during the fault ride-through, and the complex power conversion factor is recalculated based on the equivalent impedance. This can quantify the supporting effect of the SVC on voltage recovery after the fault.

[0115] In summary, this invention effectively solves the problem of misjudging system strength caused by neglecting compensation devices in traditional methods by dynamically integrating SVC reactive power compensation capacity to accurately correct the voltage support strength assessment model of new energy power plants. It innovatively adopts complex power conversion factors to quantify the reactive power interaction effects of multiple power plants, overcoming the challenge of analyzing the coupling effects of adjacent new energy clusters. It constructs a unified criterion with the positive or negative short-circuit ratio margin value as the core, transforming complex stability analysis into a standardized management and control tool that can be executed in engineering. Operation and maintenance personnel only need to monitor a single margin indicator to quickly determine the stable state and quantify the safety redundancy. At the same time, it supports the dynamic optimization of SVC reactive power output and new energy power generation plans of the power grid, significantly improving the resilience of high-proportion new energy power grids to voltage instability.

[0116] Example 3, referring to Figures 3-4 As an embodiment of the present invention, a method for evaluating the short-circuit ratio margin of SVC new energy sources is provided. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0117] Based on the PSD-BPA model, the maximum output power of the system is calculated using the continuous power flow method. System examples are established with different SVC reactive power compensation capacities. The short-circuit ratio margin of new energy power plants with reactive power compensation devices is verified by calculating the difference between the short-circuit ratio index and the critical short-circuit ratio. This is to quantitatively evaluate the feasibility and effectiveness of the new energy feed-in system on voltage support strength.

[0118] In the single-infeed system example, the parameters are set as follows: R = 0, AC system equivalent impedance Z = 0.2i / pu, short-circuit capacity Sac = 5 / pu, reactive power Q = -0.4 / pu, PV corresponding system active power P = 2.06 / pu, and operating voltage U = 0.66 / pu. Under different SVC reactive power compensation capacities, the short-circuit ratio indices are calculated for the system's critical stability state, and the impact of SVC reactive power compensation on the stability margin η is observed. SCR The effects of different SVC reactive power capacity compensation on the short-circuit ratio parameters are shown in Table 1. The changes in the short-circuit ratio control margin are also shown in Table 1. Figure 3 As shown;

[0119] Table 1. Short-circuit ratio of single-infeed systems under different SVC reactive power compensation capacities

[0120]

[0121]

[0122] In the calculation of the short-circuit ratio index of a single-infeed system, the reactive power compensation Q of the SVC is... s,i The increase in power makes the maximum transmission power P Smax The CSCR (Circuit Short-Circuit Capacity) is calculated as the ratio of short-circuit capacity to maximum transmission power. The main reason for a decrease in CSCR is the system's maximum transmission power P. Smax The decrease in CSCR, coupled with the rapid decline in CSCR, leads to a reduction in the short-circuit ratio control margin η. SCR The improvement in short-circuit ratio control margin η SCR When the value reaches 0, the new energy single-infeed system is in a critical stable state. When the short-circuit ratio control margin η SCR When η > 0, the new energy single-site access system is in a stable state, and η SCR The larger the value, the greater the relative distance between the short-circuit ratio (SCR) of a single new energy power station and the short-circuit ratio (CSCR) corresponding to the critical stable state, indicating that the system has a wider stability margin and the grid-connected system of a single new energy power station is more stable.

[0123] The multi-infeed system case comprehensively considers the interaction between multiple infeed renewable energy power plants. The Thevenin equivalent is adopted for the AC system, and the parameters are shown in Table 2. After the renewable energy capacity of grid connection points 2 and 3 is determined, the PV curve of grid connection point 1 under reactive power level Q = 0 corresponds to the system active power P = 2.5 / pu and the operating voltage U = 0.707 / pu.

[0124] Table 2 Parameters for Multi-Input Cases

[0125] AC system impedance Branch 1 Branch 2 Branch 3 0.3j 0.12j 0.8j 0.8j

[0126] Table 3 shows the changes in short-circuit ratio parameters at each grid connection point after different SVC reactive power capacity compensations, and the changes in short-circuit ratio control margin are shown in Table 3. Figure 4 As shown;

[0127] Since the branch impedances at points 2 and 3 are exactly the same, and the renewable energy grid-connected capacity is the same, according to the multi-infeed equivalent model, when the reactive power output, impedance parameters, and renewable energy grid-connected capacity at the two infeed points are symmetrical, the parameters of the renewable energy multi-station short-circuit ratio (MRSCR) and critical short-circuit ratio (CSCR) are also the same; when an SVC device is installed to compensate for reactive power, the compensation capacity Q s,i Increase, maximum transmission power P Smax As η increases, the critical short-circuit ratio (CSCR) decreases, and η decreases. MRSCR Increase the control margin η of short-circuit ratio at multiple stations MRSCR When the value reaches 0, the system is in a critical stable state. When the short-circuit ratio control margin η MRSCR When the value is greater than 0, the new energy multi-site access system is in a stable state, and the stability margin η is [value missing]. MRSCR The larger the value, the greater the relative distance between the short-circuit ratio MRSCR of the new energy multi-site grid and the short-circuit ratio CSCR corresponding to the critical stable state. This means that the system has a wider stability margin and the new energy multi-site grid-connected system is more stable.

[0128] Table 3 Short-circuit ratio index of multi-infeed system under different reactive power compensation capacities

[0129]

[0130] Example 4 illustrates a schematic scheme for an SVC (Short-Circuit Ratio Margin) assessment method for renewable energy. It should be noted that the technical solution of this SVC renewable energy short-circuit ratio margin assessment system belongs to the same concept as the technical solution of the aforementioned SVC renewable energy short-circuit ratio margin assessment method. Details not described in detail in this example of the SVC renewable energy short-circuit ratio margin assessment system can be found in the description of the aforementioned SVC renewable energy short-circuit ratio margin assessment method.

[0131] This embodiment also provides an SVC (Supply-Conditioned Dynamic Valve) short-circuit ratio margin assessment system for new energy sources, including:

[0132] The strength quantification module calculates the short-circuit ratio of voltage support strength based on the short-circuit capacity and compensation capacity of new energy grid connection, and solves the strength distortion problem by integrating the compensation capacity to correct the capacity model.

[0133] The critical determination module, based on the transmission capacity of new energy sources, calculates the critical short-circuit ratio corresponding to the stable state, analyzes the static voltage stability limit, and locates the instability boundary threshold.

[0134] The margin assessment module constructs a unified margin criterion and calculates the short-circuit ratio margin by the difference between the short-circuit ratio and the critical short-circuit ratio to assess the safety margin of new energy vehicles.

[0135] This embodiment also provides an electronic device applicable to an SVC (Short-Circuit Ratio Margin) assessment of renewable energy, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the SVC renewable energy short-circuit ratio margin assessment method proposed in the above embodiment.

[0136] This embodiment also provides a storage medium storing a computer program, which, when executed by a processor, implements an SVC (Short-Circuit Ratio Margin) assessment method for new energy sources as proposed in the above embodiments.

[0137] The storage medium proposed in this embodiment belongs to the same inventive concept as the method for evaluating the short-circuit ratio margin of SVC new energy proposed in the above embodiments. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0138] Based on the above description of the implementation methods, those skilled in the art will clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0139] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for evaluating the short-circuit ratio margin of SVC renewable energy sources, characterized in that, include: Based on the short-circuit capacity and compensation capacity of new energy grid connection, the short-circuit ratio of voltage support strength is calculated, and the capacity model is corrected by integrating compensation capacity to solve the strength distortion. Based on the new energy transmission capacity, the critical short-circuit ratio corresponding to the steady state is calculated, the static voltage stability limit is analyzed, and the instability boundary threshold is located. A unified margin criterion is constructed, and the short-circuit ratio margin is calculated by the difference between the short-circuit ratio and the critical short-circuit ratio to assess the safety margin of new energy.

2. The SVC (Short-Circuit Ratio) margin assessment method for new energy sources as described in claim 1, characterized in that, The method for calculating the short-circuit ratio of voltage support strength based on the short-circuit capacity and compensation capacity of new energy grid connection, and resolving strength distortion by integrating the compensation capacity to correct the capacity model, includes: Integrating short-circuit capacity and compensation capacity, the voltage support strength for grid connection of new energy power plants is quantified; The coupling effect of multiple power stations is calculated, and the calculation is extended by a reduction factor to obtain the grid-connected interaction intensity of multiple new energy power stations; Based on the calculation results, the short-circuit ratio index, which characterizes the strength, is output.

3. The SVC (Short-Circuit Ratio) margin assessment method for new energy sources as described in claim 2, characterized in that, The process of calculating the critical short-circuit ratio corresponding to the stable state based on the new energy transmission capacity, analyzing the static voltage stability limit, and locating the instability boundary threshold includes: Derivation of the static voltage stability point based on new energy transmission capabilities; Establish a correlation model between the short-circuit ratio and the voltage stability threshold to determine the critical short-circuit ratio for steady-state operation; The critical short-circuit ratio is used as the boundary threshold for instability to complete the stability assessment.

4. The SVC (Short-Circuit Ratio) Margin Assessment Method for New Energy Sources as described in claim 3, characterized in that, The construction of a unified margin criterion, which calculates the short-circuit ratio margin by the difference between the short-circuit ratio and the critical short-circuit ratio, and assesses the safety margin of new energy sources, includes: The short-circuit ratio margin index, which quantifies the stable boundary distance, is generated by calculating the difference between the short-circuit ratio and the critical short-circuit ratio. Based on the short-circuit ratio margin value, the stability, instability and safety level of the new energy grid-connected system are mapped; The compatibility and stability judgment criteria are based on a unified margin criterion to achieve stability assessment of new energy power plants of different scales.

5. The SVC (Short-Circuit Ratio) Margin Assessment Method for New Energy Sources as described in claim 4, characterized in that, The calculation of the difference between the short-circuit ratio and the critical short-circuit ratio includes: The stability of the system is determined by comparing the short-circuit ratio with the critical short-circuit ratio. When the critical steady state has not been reached, there is a difference range between the short-circuit ratio and the critical short-circuit ratio; The difference range represents the safety margin.

6. The SVC (Short-Circuit Ratio) margin assessment method for new energy sources as described in claim 5, characterized in that, The aforementioned compatibility stability judgment criteria, through a unified margin criterion, enable stability assessment of new energy power plants of different scales, including: The reactive power interaction effect between adjacent renewable energy power plants is dynamically quantified by complex power conversion factor, and the SVC compensation capacity is integrated into the short-circuit ratio calculation to coordinate the correction of the voltage support strength of multiple nodes, thereby eliminating the error of single power plant evaluation model on interconnection. Establish a unified stability criterion with positive and negative short-circuit ratio margin as the core.

7. The SVC (Short-Circuit Ratio) Margin Assessment Method for New Energy Sources as described in claim 6, characterized in that, The stability judgment criteria include: Stability criteria for single-infeed and multi-infeed of new energy sources; Among them, the stability criteria for a single new energy power station include that when the margin value of a single new energy power station is greater than zero, it is stable; when the margin value of a single new energy power station is less than zero, it is unstable. The stability criteria for multiple feed-in sources of renewable energy include: when the margin value of multiple renewable energy power plants is greater than zero, the plant is considered stable; when the margin value of multiple renewable energy power plants is less than zero, the plant is considered unstable.

8. A short-circuit ratio margin assessment system for SVC renewable energy, using the method described in any one of claims 1-7, characterized in that, include: The strength quantification module calculates the short-circuit ratio of voltage support strength based on the short-circuit capacity and compensation capacity of new energy grid connection, and solves the strength distortion problem by integrating the compensation capacity to correct the capacity model. The critical determination module, based on the transmission capacity of new energy sources, calculates the critical short-circuit ratio corresponding to the stable state, analyzes the static voltage stability limit, and locates the instability boundary threshold. The margin assessment module constructs a unified margin criterion and calculates the short-circuit ratio margin by the difference between the short-circuit ratio and the critical short-circuit ratio to assess the safety margin of new energy vehicles.

9. An electronic device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the SVC new energy short-circuit ratio margin assessment method according to any one of claims 1 to 7.

10. A computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the SVC (Short-Circuit Margin) assessment method for new energy sources according to any one of claims 1 to 7.

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