A new energy power station voltage support capability quantitative evaluation method and device

Abstract

The present application relates to a new energy power station voltage support capability quantitative evaluation method and device, the method comprises the following steps: determining the single machine voltage support capability evaluation index of grid-connected type new energy and grid-constructing type energy storage; taking the rated capacity of the new energy power station as the benchmark, combining the capacity proportion of different types of units in the power station, integrating the single machine voltage support capability evaluation index through normalization processing and parallel superposition principle, obtaining the overall voltage support capability evaluation index of the new energy power station; based on the overall voltage support capability evaluation index of the power station, combining the parameters of the step-up transformer and the equivalent impedance of the power grid, determining the voltage support capability evaluation index of the new energy power station at the grid connection point; based on the amplitude-frequency characteristic of the voltage support capability evaluation index of the new energy power station at the grid connection point, the voltage support capability of the new energy power station is quantitatively evaluated in the whole process. The present application can accurately depict the influence of equipment control dynamics on voltage support capability.

Description

Technical Field

[0001] This invention relates to the field of new energy power generation technology, specifically a method and device for quantitatively evaluating the voltage support capability of new energy power plants. Background Technology

[0002] Unlike traditional synchronous generators, renewable energy units, when connected to the grid via power electronic equipment, typically prioritize efficient energy conversion. During grid connection, they can only passively adapt to the grid environment and lack the ability to actively support grid voltage. With the increasing penetration rate of renewable energy, the overall voltage support capacity of the power system is declining, posing a serious challenge to the safe and stable operation of the grid. Against this backdrop, the key to building renewable energy power plants with active voltage support capabilities lies in accurately quantifying and assessing their voltage support capacity. Only by clearly defining the actual voltage support level of the power plant can a basis be provided for subsequent collaborative optimization and performance improvement.

[0003] Chinese patent document CN116454981A discloses a method and apparatus for real-time determination of voltage support strength in a new energy power system. This scheme collects real-time operating voltage and collector current at monitoring points, calculates the Thevenin equivalent potential of the system, and further calculates the short-circuit ratio, critical short-circuit ratio, and short-circuit ratio safety margin, thereby determining the strength of the voltage support strength of the new energy power system. This scheme can quickly achieve online identification of the voltage support strength of a new energy power system and has certain engineering application value. However, this scheme is essentially based on the strength classification of the short-circuit ratio and its safety margin. Its evaluation results mainly reflect the grid strength and do not deeply consider the impact of the internal control links and control parameters of new energy equipment on voltage support capability, making it difficult to reveal the differences in equipment support capability under different control parameter conditions. Furthermore, its evaluation results mainly present static indicators such as strong, medium, and weak, lacking a quantitative description of the dynamic voltage response throughout the entire process of voltage drop, support establishment, dynamic maintenance, and recovery after a disturbance, thus failing to meet the needs for a comprehensive and refined evaluation of voltage support capability.

[0004] Furthermore, real-world renewable energy power plants typically incorporate multiple resources such as wind, solar, and energy storage, and exhibit heterogeneous operation modes involving both grid connection and grid construction, making the coupling relationships between different devices more complex. Existing research mostly focuses on analyzing single wind farms or solar power plants, with few studies targeting integrated wind-solar-energy storage power plants. At the plant level, the dynamic characteristics and control behaviors of multiple power sources interact, making it difficult to directly apply voltage support capability assessment methods for individual devices. Currently, there is a lack of quantitative assessment methods for voltage support capability in such complex collaborative scenarios.

[0005] Therefore, in order to overcome the above-mentioned shortcomings in the existing technology, there is an urgent need to realize a quantitative evaluation method and device for the voltage support capability of new energy power plants. Summary of the Invention

[0006] To address the problem that existing voltage support capability assessment methods do not fully consider the dynamic response characteristics of equipment control and the dynamic coupling relationship between different devices, the purpose of this invention is to provide a quantitative assessment method for the voltage support capability of new energy power plants.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A method for quantitatively assessing the voltage support capability of new energy power plants, the method comprising the following steps:

[0009] S1. Obtain the control parameters and circuit parameters of grid-connected and grid-connected generating units, and based on the control parameters and circuit parameters, determine the single-unit voltage support capability evaluation index of grid-connected new energy and grid-connected energy storage.

[0010] S2. Based on the rated capacity of the new energy power station, and combined with the capacity ratio of different types of units in the power station, integrate the single unit voltage support capability assessment indicators to determine the overall voltage support capability assessment indicators of the new energy power station.

[0011] S3. Based on the parameters of the step-up transformer and the equivalent impedance of the power grid, the overall voltage support capability assessment index is converted to determine the voltage support capability assessment index of the new energy power station at the grid connection point.

[0012] S4. Based on the amplitude-frequency characteristics of the voltage support capability assessment index of new energy power plants at the grid connection point, the voltage support capability of new energy power plants is quantitatively assessed.

[0013] Further, step S1 specifically includes:

[0014] S11. Determination of Grid-Connected Single Unit Indicators: Obtain the PV control parameters and circuit parameters of the grid-connected renewable energy unit, and combine them with the current system's steady-state operating data to determine the voltage support capability assessment index Γ of a single grid-connected renewable energy unit. GFL (s);

[0015] S12. Determination of Single Unit Indicators for Grid-Type Energy Storage Units: Obtain the virtual synchronous machine control parameters and circuit parameters of the grid-type energy storage unit, and combine them with the current steady-state operation data of the system to determine the voltage support capability evaluation index Γ of a single grid-type energy storage unit. GFM (s).

[0016] Further, step S2 specifically includes:

[0017] S21. Standardization: Based on the rated capacity S of the new energy power plant NBased on this, the evaluation indicators of voltage support capability of grid-connected new energy single unit and the evaluation indicators of voltage support capability of grid-connected energy storage single unit obtained in step S1 are standardized.

[0018] S22. Superposition Calculation: Based on the actual capacity ratio of grid-connected and grid-connected units within the new energy power plant, the two types of single-unit indicators that have undergone per-unit processing are superimposed and calculated using the principle of parallel superposition to obtain the overall voltage support capability evaluation index Γ(s) of the new energy power plant.

[0019] Further, step S3 specifically includes:

[0020] S31. Parameter Acquisition and Per-unit Standardization: Obtain the rated capacity S of the power station's step-up transformer. T and leakage resistance X T And for leakage resistance X T Perform per-unit processing;

[0021] S32. Grid Connection Point Indicator Conversion: Based on the standardized overall voltage support capability assessment index of the power station, and combined with the standardized transformer leakage reactance and the equivalent reactance of the power grid, the voltage support capability assessment index Γ of the new energy power station at the grid connection point is calculated. PCC (s).

[0022] Further, step S4 specifically includes:

[0023] S41. Plotting the amplitude-frequency response curve: Plotting the grid connection point voltage support capability assessment index Γ. PCC (s) amplitude-frequency response curve;

[0024] S42. Voltage Support Capability Analysis: Based on the amplitude-frequency characteristic curve and the representational significance of different frequency bands of the curve, the voltage support capability of the new energy power station is analyzed to achieve a full-process quantitative assessment of the voltage support capability of the new energy power station.

[0025] Furthermore, the evaluation index Γ of the grid-connected single-unit voltage support capability... GFL The formula for calculating (s) is:

[0026] ;

[0027] In the formula, ∆Q e_L To track the change in reactive power output of grid-connected renewable energy, ∆U t U represents the change in port voltage during reactive power disturbance. c0_L To determine the steady-state value of the internal potential of the grid-connected unit, U t0 X is the steady-state value of the port voltage. f_L For the filter reactance of the grid-connected unit, k up k is the proportional parameter of the outer loop PI controller for the terminal voltage. uiThese are the integral parameters of the outer loop PI controller for the terminal voltage.

[0028] The evaluation index of the voltage support capability of the network-type single unit Γ GFM The formula for calculating (s) is:

[0029] ;

[0030] In the formula, ∆Q e_M ∆U represents the change in reactive power output of grid-type energy storage. t U represents the change in port voltage during reactive power disturbance. c0_M U is the steady-state value of the internal potential of a grid-connected unit. t0 X is the steady-state value of the port voltage. f_M For the filter reactor of the grid-type unit, D q is the reactive power-voltage droop coefficient, and K is the reactive power loop integral coefficient.

[0031] Furthermore, the standardized overall voltage support capability evaluation index Γ(s) of the new energy power station is:

[0032] ;

[0033] In the formula, n represents the number of grid-connected new energy generating units, and Γ GFL (s) is an evaluation index for the voltage support capability of a single unit in grid-connected new energy vehicles. GFL To match the rated capacity of a single unit in grid-connected new energy vehicles, S N m represents the rated capacity of the new energy power plant; m represents the number of grid-connected energy storage units; Γ represents the rated capacity of the new energy power plant. GFM (s) is an evaluation index for the voltage support capability of a single unit in a grid-type energy storage system. GFM This refers to the rated capacity of a single grid-type energy storage unit.

[0034] The voltage support capability assessment index at the grid connection point Γ PCC The formula for calculating (s) is:

[0035] ;

[0036] In the formula, Γ(s) is the evaluation index of the overall voltage support capability of new energy power plants after standardization, and X T For the leakage reactance of the step-up transformer in the new energy power plant, S N For the rated capacity of new energy power plants, S T X is the rated capacity of the step-up transformer. g It is the equivalent reactance of the power grid.

[0037] In a second aspect of the present invention, a device for quantitatively evaluating the voltage support capability of a new energy power station is disclosed, the device comprising:

[0038] The single-unit evaluation index acquisition module is used to acquire the control parameters and circuit parameters of grid-connected and grid-connected units, and based on the control parameters and circuit parameters, determine the single-unit voltage support capability evaluation index of grid-connected new energy and grid-connected energy storage.

[0039] The overall evaluation index acquisition module is used to determine the overall voltage support capability evaluation index of the new energy power station by taking the rated capacity of the new energy power station as the benchmark, combining the capacity ratio of different types of units in the power station, integrating the single unit voltage support capability evaluation index, and determining the overall voltage support capability evaluation index of the new energy power station.

[0040] The grid connection point assessment index acquisition module is used to calculate the overall voltage support capability assessment index based on the step-up transformer parameters and the grid equivalent impedance, and determine the voltage support capability assessment index of the new energy power station at the grid connection point.

[0041] The quantitative assessment module is used to quantitatively assess the voltage support capability of new energy power plants based on the amplitude-frequency characteristics of the voltage support capability assessment index at the grid connection point.

[0042] In a third aspect of the invention, an electronic device is disclosed, comprising: at least one processor; and a memory storing instructions that, when executed by the at least one processor, cause the at least one processor to perform the quantitative evaluation method for the voltage support capability of new energy power plants.

[0043] In a fourth aspect of the invention, a machine-readable storage medium is disclosed, which stores executable instructions that, when executed, cause the machine to perform the quantitative evaluation method for the voltage support capability of new energy power plants.

[0044] Compared with the prior art, the advantages of the present invention are:

[0045] (1) This invention establishes a voltage support capability assessment index that considers the dynamic response process of internal electromotive force by introducing equipment control parameters. This makes the assessment model not only include external information such as grid-side short-circuit capacity, but also reflect the effect of converter control parameters on voltage dynamic support capability. Thus, it solves the technical problem that existing technologies cannot quantify the impact of internal control dynamics of new energy equipment on voltage support capability, realizes the expansion from "grid external strength assessment" to "equipment control dynamic support capability assessment", improves the accuracy of assessment results, and can provide a basis for control parameter tuning, control strategy optimization and power plant support capability improvement.

[0046] (2) This invention constructs an evaluation index Γ for voltage support capability at the grid connection point. PCC(s) and analyze its amplitude-frequency characteristics. The low-frequency amplitude characteristics are used to characterize the power station's ability to recover from steady-state voltage deviations, while the high-frequency amplitude characteristics are used to characterize the power station's dynamic suppression capability against rapid reactive power fluctuations. This achieves a quantitative assessment of the entire process of voltage support capability of new energy power stations from transient to steady state. This technology overcomes the limitations of existing methods that can only assess steady-state results and are difficult to characterize rapid dynamic support capabilities. It enables the assessment results to simultaneously reflect voltage support performance at different time scales within the same framework, providing a more targeted basis for voltage safety analysis and dispatch decisions of new energy power stations.

[0047] (3) This invention utilizes the principle of parallel superposition and per-unit processing, taking the rated capacity of the new energy power station as a unified benchmark, and uniformly models n grid-connected units and m grid-connected units, further considering the impact of the leakage reactance of the step-up transformer and the equivalent reactance of the power grid on the support capability. Through this technical feature, units with different control types and different capacity levels can be included in the same voltage support capability assessment framework, thereby breaking through the limitation of the existing single-unit model being unable to describe the overall support capability of heterogeneous new energy power stations. Attached Figure Description

[0048] Figure 1 This is a topology diagram of a typical new energy power plant grid-connected system;

[0049] Figure 2 This is a control block diagram for grid-type new energy PV;

[0050] Figure 3 This is a control block diagram of a grid-type energy storage virtual synchronous machine provided in an embodiment of the present invention;

[0051] Figure 4 This is a flowchart of the quantitative evaluation method for the voltage support capability of new energy power plants in this invention;

[0052] Figure 5 This is a simulation topology diagram of a hybrid new energy power station including 3MW of grid-connected new energy and 0.5MW of grid-connected energy storage, provided in an embodiment of the present invention.

[0053] Figure 6(a) is the amplitude-frequency characteristic curve of the voltage support capability evaluation index under scenario I of the present invention;

[0054] Figure 6(b) shows the reactive power output response of the system when it faces a rapid reactive power disturbance in scenario I of the present invention.

[0055] Figure 6(c) shows the dynamic voltage response at the grid connection point when the system faces rapid reactive power disturbance in scenario I of the present invention.

[0056] Figure 7(a) is the amplitude-frequency characteristic curve of the grid connection point voltage support capability evaluation index under scenario II of the present invention;

[0057] Figure 7(b) shows the reactive power output response of the system when faced with rapid reactive power disturbance under scenario II of the present invention.

[0058] Figure 7(c) shows the dynamic voltage response at the grid connection point when the system faces rapid reactive power disturbance under scenario II of the present invention.

[0059] Figure 8(a) is the amplitude-frequency characteristic curve of the grid connection point voltage support capability evaluation index under Example Scenario III of the present invention;

[0060] Figure 8(b) shows the reactive power output response of the system when faced with rapid reactive power disturbance under scenario III of the present invention.

[0061] Figure 8(c) shows the dynamic voltage response at the grid connection point when the system faces rapid reactive power disturbance under scenario III of the present invention.

[0062] Figure 9(a) is the amplitude-frequency characteristic curve of the grid connection point voltage support capability evaluation index under scenario IV of the present invention;

[0063] Figure 9(b) shows the reactive power output response of the system when faced with rapid reactive power disturbance under scenario IV of the present invention.

[0064] Figure 9(c) shows the dynamic voltage response at the grid connection point when the system faces rapid reactive power disturbance under scenario IV of the present invention. Detailed Implementation

[0065] To provide a better understanding of the structural features and effects achieved by the present invention, a detailed description is provided below, accompanied by preferred embodiments and accompanying drawings:

[0066] Example 1

[0067] This invention provides a method for quantitatively evaluating the voltage support capability of new energy power plants. This method achieves quantitative evaluation of the voltage support capability of new energy power plants by establishing a frequency domain model that considers control dynamics. The method includes: quantitative evaluation of the voltage support capability of grid-connected new energy plants, quantitative evaluation of the voltage support capability of grid-connected energy storage plants, and quantitative evaluation of the voltage support capability of integrated wind-solar-storage new energy power plants.

[0068] This invention defines the ratio of reactive power change to voltage amplitude change in the frequency domain as the voltage support capability assessment index Γ(s), and its expression is:

[0069] ;

[0070] In the formula, ΔQ PCC ΔU represents the reactive power disturbance at the grid connection point. PCCThis indicates the voltage amplitude disturbance at the grid connection point. This indicator can comprehensively characterize the ability of a new energy power plant to withstand voltage disturbances throughout the entire transient-steady-state process.

[0071] Figure 1 A topology diagram of a typical new energy power plant grid-connected system, such as Figure 1 As shown, the photovoltaic, energy storage, and wind turbine units are respectively filtered through LCL filters (the filter reactance of each branch is as follows). , , The filter capacitors are respectively , , The voltage is collected at the 690V low-voltage bus, then connected to the 35kV grid connection point via the step-up transformer T1, and finally processed by the grid equivalent reactance. Connect to the power grid.

[0072] The grid-connected new energy control structure adopted in this invention is as follows: Figure 2 As shown, this structure is a dual-loop control and phase-locked loop architecture. The control logic of this structure is as follows:

[0073] (1) Terminal voltage outer loop

[0074] port voltage Compared with reference value The deviation is the input, which is then processed by the PI controller. V Generate reactive current reference value The deviation is the input, and the actual reactive current. After comparison, the current loop PI controller PI I Generate internal potential reference value .

[0075] (2) Active outer ring

[0076] With actual active power P e Compared with reference value P ref The deviation is the input, which is then processed by the PI controller. p Generate active current reference value , and the actual active current i d After comparison, the current loop PI controller PI I Generate internal potential reference value U cdref .

[0077] (3) Phase-locked loop

[0078] For port voltage U t The phase is obtained by performing dq decomposition and then passing it through a PI controller and an integrator. It is used for dq / abc coordinate transformation, and finally outputs the three-phase internal potential reference value U. cabcref .

[0079] Grid-connected new energy sources adopt PV control, taking into account the dynamic control characteristics of the equipment. When reactive power disturbances occur at the grid connection point, it can provide reactive power response ∆Q. e_L Based on the above grid-connected new energy control structure, this embodiment uses the rated capacity S of a single grid-connected new energy unit. GFL Rated voltage U B Based on this, the voltage support capability assessment index Γ of a single grid-connected renewable energy unit is determined using the following formula. GFL (s):

[0080] ;

[0081] In the formula, ∆Q e_L To track the change in reactive power output of grid-connected renewable energy, ∆U t U represents the change in port voltage during reactive power disturbance. c0_L To determine the steady-state value of the internal potential of the grid-connected unit, U t0 X is the steady-state value of the port voltage. f_L For the filter reactance of the grid-connected unit, k up k is the proportional parameter of the outer loop PI controller for the terminal voltage. ui These are the integral parameters of the outer loop PI controller for the terminal voltage.

[0082] When n grid-connected renewable energy units are operating in parallel, their total voltage support capacity is demonstrated to the outside world. This can be expressed as the sum of the voltage support capabilities of a single converter:

[0083] ;

[0084] In the formula, ∆Q e_L1 ,…,∆Q e_Ln The reactive power change of the i-th grid-connected new energy source is ∆U. t Γ represents the change in port voltage. GFLi (s) is the voltage support capability evaluation index of the i-th converter.

[0085] The grid-type energy storage control structure used in this invention is as follows: Figure 3 As shown, the core control parameters include:

[0086] (1) Reactive power loop integral coefficient K: determines the dynamic response speed and steady-state accuracy of reactive power regulation;

[0087] (2) Reactive power-voltage droop coefficient D q This reflects the active support strength of the grid-type unit against voltage disturbances.

[0088] Grid-based energy storage employs virtual synchronous machine control. Considering the dynamic control characteristics of the equipment, it can provide reactive power response ∆Q when reactive power disturbances occur at the grid connection point. e_MThe rated capacity S of a single-unit grid-type energy storage system GFM Rated voltage U B Based on this, the evaluation index Γ of the single-unit voltage support capability is determined using the following formula. GFM (s):

[0089] ;

[0090] In the formula, ∆Q e_M ∆U represents the change in reactive power output of grid-type energy storage. t U represents the change in port voltage during reactive power disturbance. c0_M U is the steady-state value of the internal potential of a grid-connected unit. t0 X is the steady-state value of the port voltage. f_M For the filter reactor of the grid-type unit, D q is the reactive power-voltage droop coefficient, and K is the reactive power loop integral coefficient.

[0091] When m grid-type energy storage units are operating in parallel, their total voltage support capability is demonstrated to the outside world. This can be expressed as a linear superposition of the voltage support capabilities of a single converter:

[0092] ;

[0093] In the formula, ∆Q e_M1 ,…,∆Q e_Mm These represent the reactive power change output of the i-th grid-connected energy storage unit, ∆U. t Γ represents the change in port voltage. GFMi (s) is the voltage support capability evaluation index of the i-th converter.

[0094] Assume the new energy power station consists of n units with a rated capacity of S GFL The grid-connected new energy and m units with a rated capacity of S GFM The grid-type energy storage system together constitutes the main structure of the new energy power station, and the rated capacity of the new energy power station is:

[0095] S N =n×S GFL +m×S GFM .

[0096] Unify all variables to the rated capacity S N Rated voltage U B Using the per-unit value as the benchmark, the evaluation index Γ(s) of the voltage support capability at the power station level for new energy power plants is obtained as follows:

[0097] ;

[0098] In the formula, ∆Q e_Li For the reactive power change of the i-th grid-connected renewable energy source, ∆U t∆Q represents the change in port voltage. e_Mi Let i be the reactive power change output of the i-th grid-type energy storage unit. The total voltage support capacity demonstrated by n grid-connected renewable energy units when operating in parallel; S GFL To match the rated capacity of a single unit in grid-connected new energy vehicles, S N This refers to the rated capacity of the new energy power plant. When m grid-type energy storage units are connected in parallel, the total voltage support capability exhibited externally, S GFM This refers to the rated capacity of a single grid-type energy storage unit.

[0099] For the same renewable energy power plant, the control parameters and filter reactance of all grid-connected renewable energy sources, as well as the control parameters and filter reactance of all grid-connected energy storage sources, are usually taken to have the same values. Therefore, when the control parameters and filter reactance of all grid-connected renewable energy sources and grid-connected energy storage sources in the power plant are the same, the above expression can be simplified to:

[0100] ;

[0101] In the formula, n represents the number of grid-connected new energy generating units, and Γ GFL (s) is an evaluation index for the voltage support capability of a single unit in grid-connected new energy vehicles. GFL To match the rated capacity of a single unit in grid-connected new energy vehicles, S N m represents the rated capacity of the new energy power plant; m represents the number of grid-connected energy storage units; Γ represents the rated capacity of the new energy power plant. GFM (s) is an evaluation index for the voltage support capability of a single unit in a grid-type energy storage system. GFM This refers to the rated capacity of a single grid-type energy storage unit.

[0102] Taking into account the leakage reactance X of the step-up transformer T and according to the power station's rated capacity S N After standardization, the voltage support capability assessment index Γ at the grid connection point can be obtained. PCC (s):

[0103] ;

[0104] In the formula, Γ(s) is the evaluation index of the overall voltage support capability of new energy power plants after standardization, and X T For the leakage reactance of the step-up transformer in the new energy power plant, S N For the rated capacity of new energy power plants, S T X is the rated capacity of the step-up transformer. g It is the equivalent reactance of the power grid.

[0105] As can be seen from the above formula, the evaluation index of grid connection point voltage support capability consists of two parts: one part is the equivalent reactance of the power grid. One part is determined by the power grid itself, which is a constant value and represents the grid's ability to support voltage disturbances. The other part is determined by the new energy power station, which is the frequency domain dynamic contribution of the power station to the voltage support capability at the grid connection point after the power station is connected. This value is related to the dynamic control characteristics of grid-connected and grid-structured energy storage and represents the frequency domain admittance characteristics of the new energy power station.

[0106] Based on the above, this invention provides a method for quantitatively evaluating the voltage support capability of new energy power plants, such as... Figure 4 As shown, the method includes the following steps:

[0107] S1. Obtain the control parameters and circuit parameters of grid-connected and grid-connected generating units. Based on the control parameters and circuit parameters, determine the single-unit voltage support capability evaluation index of grid-connected new energy and grid-connected energy storage respectively.

[0108] Step S1 specifically includes:

[0109] S11. Determination of Grid-Connected Single Unit Indicators: Obtain the PV control parameters and circuit parameters of the grid-connected renewable energy unit, combine them with the current system's steady-state operating data, and substitute them into the evaluation index calculation formula to determine the voltage support capability evaluation index Γ of a single grid-connected renewable energy unit. GFL (s) is used to quantify its dynamic reactive power response capability under voltage disturbances. The PV control parameters of the grid-connected renewable energy unit include the proportional coefficient k of the terminal voltage controller. up and integral coefficient k ui The circuit parameters of the grid-connected new energy unit include the filter reactance X. f_L The current steady-state operating data of the system includes the converter internal potential U. c0_L Port voltage U t0 wait.

[0110] S12. Calculate the voltage support capability assessment index of grid-type energy storage: Obtain the virtual synchronous machine control parameters and circuit parameters of the grid-type energy storage unit, combine them with the current steady-state operation data of the system, substitute them into the assessment index calculation formula, and determine the voltage support capability assessment index Γ of a single grid-type energy storage unit. GFM (s) is used to quantify its dynamic reactive power response capability under voltage disturbances. The virtual synchronous machine control parameters of the grid-type energy storage unit include the reactive power loop integral coefficient K and the reactive power-voltage droop coefficient D. q The circuit parameters of the grid-type energy storage unit include the filter reactance X. f_M The current steady-state operating data of the system includes the converter internal potential U. c0_L Port voltage U t0 wait.

[0111] S2. Based on the rated capacity of the new energy power station, and combined with the capacity ratio of different types of units in the power station, the single-unit voltage support capability assessment index is integrated through per-unit processing and parallel superposition principle to obtain the overall voltage support capability assessment index of the new energy power station.

[0112] Step S2 specifically includes:

[0113] S21. Standardization: Based on the rated capacity S of the new energy power plant N Based on this, the voltage support capability assessment indicators for grid-connected new energy single-unit and grid-connected energy storage single-unit obtained in step S1 are standardized. Standardization eliminates the impact of differences in rated capacity between different units, enabling the comparison and aggregation of the two types of unit indicators.

[0114] S22. Superposition Calculation: Based on the actual capacity ratio of grid-connected and grid-connected units within the new energy power plant, the two types of single-unit indicators after standardization are superimposed using the principle of parallel superposition to obtain the overall voltage support capability assessment index Γ(s) of the new energy power plant. This index can accurately characterize the total reactive power response characteristics of the new energy power plant under the synergistic effect of grid-connected and grid-connected heterogeneous power sources, laying the foundation for subsequent grid connection point voltage support capability assessment.

[0115] S3. Based on the overall voltage support capability assessment index of the power station, combined with the parameters of the step-up transformer and the equivalent impedance of the power grid, determine the voltage support capability assessment index of the new energy power station at the grid connection point.

[0116] Step S3 specifically includes:

[0117] S31. Parameter Acquisition and Per-unit Standardization: Obtain the rated capacity S of the power station's step-up transformer. T and leakage resistance X T And for leakage resistance X T Perform per-unit processing;

[0118] S32. Grid Connection Point Indicator Conversion: Based on the standardized overall voltage support capability assessment index of the power station, and combined with the standardized transformer leakage reactance and the equivalent reactance of the power grid, the voltage support capability assessment index Γ of the new energy power station at the grid connection point is calculated. PCC (s).

[0119] S4. Based on the amplitude-frequency characteristics of the voltage support capability assessment index of new energy power plants at the grid connection point, conduct a full-process quantitative assessment of the voltage support capability of new energy power plants.

[0120] Step S4 specifically includes:

[0121] S41. Plotting the amplitude-frequency response curve: Plotting the grid connection point voltage support capability assessment index Γ.PCC (s) amplitude-frequency response curve;

[0122] S42. Voltage Support Capability Analysis: Based on the amplitude-frequency characteristic curve and the representative meaning of different frequency bands of the curve, the voltage support capability of the new energy power station is analyzed, thereby achieving a quantitative assessment of the entire process of the voltage support capability of the new energy power station. Wherein, Γ PCC The amplitude of the amplitude-frequency characteristic curve (s) in the low-frequency band represents the power station's ability to recover from steady-state voltage deviation, while the amplitude in the high-frequency band represents the power station's ability to dynamically suppress rapid reactive power fluctuations.

[0123] To verify the effectiveness of the quantitative evaluation method for voltage support capability of new energy power plants provided by this invention, the following simulation verification process is designed.

[0124] (1) Frequency domain analysis scenario

[0125] To verify the effectiveness of the quantitative evaluation method for voltage support capability of new energy power plants provided by this invention, the voltage support capability evaluation index Γ obtained based on this method is analyzed. PCC The amplitude-frequency response curves are analyzed. Since the primary focus is on the voltage support capability of renewable energy power plants under rapid reactive power disturbances, only the dynamic response at the voltage control scale (~10Hz) is considered, and the frequency range of the Bode plot is set to 1Hz~100Hz. The control parameters k for different grid-connected renewable energy and grid-connected energy storage systems are analyzed. up k ui Under the conditions of K and Dq, the effects of different values ​​on the voltage support capability of the grid connection point are compared and analyzed.

[0126] (2) Time-domain simulation scenario

[0127] To further illustrate the effectiveness of the quantitative evaluation method for voltage support capability of new energy power plants proposed in this invention, a specific embodiment is described below:

[0128] This implementation method takes a hybrid renewable energy power station containing 3MW of grid-connected renewable energy and 0.5MW of grid-connected energy storage as an example for simulation research, such as... Figure 5 As shown in Table 1, the key system parameters are as follows: 0.5 Mvar reactive load is applied at the grid connection point at t=2s, and the load is removed 100ms later to simulate rapid reactive power fluctuations in the system. The accuracy of the frequency domain indicators is verified by the time domain waveform, which intuitively reflects the voltage support effect of the power station under rapid reactive power disturbances.

[0129] Table 1

[0130] parameter symbol numerical values Steady-state value of internal electromotive force of grid-connected new energy <![CDATA[U c0_L ]]> 1.01pu Grid-connected new energy rated capacity <![CDATA[S GFL ]]> 3MW Grid-type new energy filter reactor <![CDATA[X f_L ]]> 0.08pu Steady-state value of internal potential of grid-type energy storage <![CDATA[U c0_M ]]> 1.01pu Grid-type energy storage rated capacity <![CDATA[S GFM ]]> 0.5MW Network-type energy storage filter reactor <![CDATA[X f_M ]]> 0.08pu Converter output voltage <![CDATA[U t0 ]]> 1.00pu Voltage reference value <![CDATA[U B ]]> 690V Rated capacity of new energy power plants <![CDATA[S N ]]> 3.5MW Step-up transformer rated capacity <![CDATA[S T ]]> 5MW Leakage reactance of step-up transformer <![CDATA[X T ]]> 0.08pu DC side voltage <![CDATA[U dc ]]> 2070V Transmission line resistance <![CDATA[R g ]]> 0.04pu Transmission line reactance <![CDATA[X g ]]> 0.3pu Active power controller parameters <![CDATA[K pp ,K pi ]]> 0.05 pu 10 p.u. AC voltage controller parameters <![CDATA[K up ,K ui ]]> 5p.u. 150p.u. Current controller parameters <![CDATA[K ip ,K ii ]]> 1p.u. 10p.u. Resistor of grid-type new energy filter <![CDATA[R f_L ]]> 0.008pu Grid-type new energy filter reactance <![CDATA[X f_L ]]> 0.08pu Active-phase control parameters <![CDATA[J,D p ]]> 2p.u. 150p.u. Reactive power-amplitude control parameters <![CDATA[K,D q ]]> 0.5 pu 3 p.u. Network-type new energy filter resistor <![CDATA[R f_M ]]> 0.008pu Network-type new energy filter reactance <![CDATA[X f_M ]]> 0.08pu

[0131] Specifically, the control parameters for grid-connected new energy and grid-based energy storage in each scenario in this embodiment are set as follows:

[0132] Scenario I: Change the proportional coefficient k of the grid-connected new energy terminal voltage controller up =3, 5, 10, and other parameters are shown in Table 1.

[0133] Scenario II: Change the integral coefficient k of the grid-connected renewable energy terminal voltage controller ui =50, 100, 150, other parameters are shown in Table 1.

[0134] Scenario III: Change the reactive power loop integral coefficient K of the grid-type energy storage to 0.1, 0.5, and 2, and other parameters are shown in Table 1.

[0135] Scenario IV: Changing the voltage control parameter D of the grid-type energy storage terminal q =1, 6, 20, and other parameters are shown in Table 1.

[0136] Figure 6(a) shows the grid connection point voltage support capability evaluation index Γ under scenario I. PCC The amplitude-frequency response curves, Figures 6(b) and 6(c), show the reactive power output response and grid connection point voltage dynamic change waveforms of the system under scenario I when facing rapid reactive power disturbances. As can be seen from Figure 6(a), in the frequency band above 10Hz, increasing the scaling factor k... up This can significantly improve the corresponding value of the amplitude-frequency curve. This indicates that by increasing the scaling factor, the evaluation index Γ... PCC It can maintain a higher amplitude over a wider frequency range, thereby enhancing the ability of new energy power plants to suppress and support voltage disturbances in this frequency band. As can be seen from Figures 6(b) and 6(c), the scaling factor k... up For ΔQ e The impact was already evident in the early stages of the disturbance, and with k up As the voltage increases, the lowest point of the grid connection voltage rises accordingly, and the recovery speed accelerates significantly.

[0137] Figure 7(a) shows the grid connection point voltage support capability evaluation index Γ under scenario II. PCC The amplitude-frequency characteristic curves, Figures 7(b) and 7(c), show the reactive power output response and grid connection point voltage dynamic change waveforms of the system under scenario II when facing rapid reactive power disturbances. As can be seen from Figure 7(a), with the integral coefficient k... ui Increase the evaluation index Γ near 10Hz PCC The amplitude increases significantly, indicating that the integral coefficient has a strong influence on the dynamic response in the mid-to-low frequency range. However, in the high-frequency region near 100Hz, increasing k... ui For Γ PCC The increase in amplitude is relatively limited, indicating that the integral coefficient has a weak impact on improving the voltage support capability during disturbances. As can be seen from Figures 7(b) and 7(c), the integral coefficient k... ui For ΔQe and ΔU PCC The impact is mainly reflected in the middle and later stages of the disturbance, with a relatively small impact on the instantaneous response. As k... ui The voltage increases, but the lowest point of the grid connection voltage does not change significantly; however, the voltage recovery speed improves.

[0138] Figure 8(a) shows the grid connection point voltage support capability evaluation index Γ under Scenario III. PCC The amplitude-frequency response curves, Figures 8(b) and 8(c), show the reactive power output response and grid connection point voltage dynamic changes of the system under scenario III when facing rapid reactive power disturbances. As can be seen from Figure 8(a), with the increase of the reactive power loop integral coefficient K, the amplitude of the amplitude-frequency curve increases significantly in the 10Hz~100Hz frequency band, indicating that K mainly improves the system's Γ in the high-frequency band. PCC As can be seen from Figures 8(b) and 8(c), the reactive power output increases after the disturbance as the value of K increases. Furthermore, when K=0.1, the lowest voltage drop at the grid connection point is significantly lower than that under the conditions of K=0.5 and K=2, indicating that a smaller integral coefficient will lead to insufficient system voltage support capability. However, when K is further increased from 0.5 to 2, there is no significant difference in the corresponding minimum voltage, indicating that as K continues to increase, its effect on improving the voltage support capability in the high-frequency range gradually weakens, exhibiting saturation characteristics.

[0139] Figure 9(a) shows the grid connection point voltage support capability evaluation index Γ under scenario IV. PCC The amplitude-frequency characteristic curves, Figures 9(b) and 9(c), show the reactive power output response and grid connection point voltage dynamic change waveforms of the system under scenario IV when facing rapid reactive power disturbances. As can be seen from Figure 9(a), with the increase in the terminal voltage control coefficient D... q The increase in amplitude is more pronounced in the 10Hz~100Hz frequency band, indicating that D q Its main function is to improve the Γ frequency band in the initial stage of the disturbance. PCC As can be seen from Figures 9(b) and 9(c), with D... q As the voltage increases, the reactive power output increases after the disturbance, the rate of voltage drop at the grid connection point slows down, the steep drop characteristic of the voltage waveform in the early stage of the disturbance is suppressed, and the minimum point of the grid connection point voltage increases accordingly during the dynamic process.

[0140] Example 2

[0141] A device for quantitatively evaluating the voltage support capability of a new energy power station, the device comprising:

[0142] The single-unit evaluation index acquisition module is used to acquire the control parameters and circuit parameters of grid-connected and grid-connected units, and based on the control parameters and circuit parameters, determine the single-unit voltage support capability evaluation index of grid-connected new energy and grid-connected energy storage.

[0143] The overall evaluation index acquisition module is used to determine the overall voltage support capability evaluation index of the new energy power station by taking the rated capacity of the new energy power station as the benchmark, combining the capacity ratio of different types of units in the power station, integrating the single unit voltage support capability evaluation index, and determining the overall voltage support capability evaluation index of the new energy power station.

[0144] The grid connection point assessment index acquisition module is used to calculate the overall voltage support capability assessment index based on the step-up transformer parameters and the grid equivalent impedance, and determine the voltage support capability assessment index of the new energy power station at the grid connection point.

[0145] The quantitative assessment module is used to quantitatively assess the voltage support capability of new energy power plants based on the amplitude-frequency characteristics of the voltage support capability assessment index at the grid connection point.

[0146] Example 3

[0147] An electronic device includes: at least one processor; and a memory storing instructions that, when executed by the at least one processor, cause the at least one processor to perform the aforementioned quantitative assessment method for the voltage support capability of new energy power plants.

[0148] In this embodiment, the electronic device may include, but is not limited to: personal computer, server computer, workstation, desktop computer, laptop computer, notebook computer, mobile computing device, smartphone, tablet computer, cellular phone, personal digital assistant (PDA), handheld device, messaging device, wearable computing device, consumer electronic device, etc.

[0149] Example 4

[0150] A machine-readable storage medium storing executable instructions that, when executed, cause the machine to perform the aforementioned quantitative assessment method for the voltage support capability of new energy power plants.

[0151] Specifically, a system or apparatus equipped with a readable storage medium storing software program code that implements the functions of any of the embodiments described above, and enabling the computer or processor of the system or apparatus to read and execute instructions stored in the readable storage medium. In this case, the program code read from the readable medium itself can implement the functions of any of the embodiments described above; therefore, the machine-readable code and the readable storage medium storing the machine-readable code constitute a part of this specification. Embodiments of the readable storage medium include floppy disks, hard disks, magneto-optical disks, optical disks (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD-RW), magnetic tapes, non-volatile memory cards, and ROMs. Alternatively, the program code can be downloaded from a server computer or the cloud via a communication network. Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied 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. The present invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations 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 flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 The 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 operate 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.

[0152] 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 1One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0153] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A method for quantitatively evaluating the voltage support capability of new energy power plants, characterized in that, The method includes the following steps: S1. Obtain the control parameters and circuit parameters of grid-connected and grid-connected generating units, and based on the control parameters and circuit parameters, determine the single-unit voltage support capability evaluation index of grid-connected new energy and grid-connected energy storage. S2. Based on the rated capacity of the new energy power station, and combined with the capacity ratio of different types of units in the power station, integrate the single unit voltage support capability assessment indicators to determine the overall voltage support capability assessment indicators of the new energy power station. S3. Based on the parameters of the step-up transformer and the equivalent impedance of the power grid, the overall voltage support capability assessment index is converted to determine the voltage support capability assessment index of the new energy power station at the grid connection point. S4. Based on the amplitude-frequency characteristics of the voltage support capability assessment index of new energy power plants at the grid connection point, the voltage support capability of new energy power plants is quantitatively assessed.

2. The method for quantitatively evaluating the voltage support capability of new energy power plants according to claim 1, characterized in that, Step S1 specifically includes: S11. Determination of Grid-Connected Single Unit Indicators: Obtain the PV control parameters and circuit parameters of the grid-connected renewable energy unit, and combine them with the current system's steady-state operating data to determine the voltage support capability assessment index Γ of a single grid-connected renewable energy unit. GFL (s); S12. Determination of Single Unit Indicators for Grid-Type Energy Storage Units: Obtain the virtual synchronous machine control parameters and circuit parameters of the grid-type energy storage unit, and combine them with the current steady-state operation data of the system to determine the voltage support capability evaluation index Γ of a single grid-type energy storage unit. GFM (s).

3. The quantitative evaluation method for voltage support capability of new energy power plants according to claim 2, characterized in that, Step S2 specifically includes: S21. Per-unit processing: Based on the rated capacity S of the new energy power station N Based on this, the evaluation indicators of voltage support capability of grid-connected new energy single unit and the evaluation indicators of voltage support capability of grid-connected energy storage single unit obtained in step S1 are standardized. S22. Superposition Calculation: Based on the actual capacity ratio of grid-connected and grid-connected units within the new energy power plant, the two types of single-unit indicators that have undergone per-unit processing are superimposed and calculated using the principle of parallel superposition to obtain the overall voltage support capability evaluation index Γ(s) of the new energy power plant.

4. The method for quantitatively evaluating the voltage support capability of new energy power plants according to claim 3, characterized in that, Step S3 specifically includes: S31. Parameter Acquisition and Per-unit Standardization: Obtain the rated capacity S of the power station's step-up transformer. T and leakage resistance X T And for leakage resistance X T Perform per-unit processing; S32. Grid Connection Point Indicator Conversion: Based on the standardized overall voltage support capability assessment index of the power station, and combined with the standardized transformer leakage reactance and the equivalent reactance of the power grid, the voltage support capability assessment index Γ of the new energy power station at the grid connection point is calculated. PCC (s).

5. The quantitative evaluation method for voltage support capability of new energy power plants according to claim 4, characterized in that, Step S4 specifically includes: S41. Plotting the amplitude-frequency response curve: Plotting the grid connection point voltage support capability assessment index Γ. PCC (s) amplitude-frequency response curve; S42. Voltage Support Capability Analysis: Based on the amplitude-frequency characteristic curve and the representational significance of different frequency bands of the curve, the voltage support capability of the new energy power station is analyzed to achieve a full-process quantitative assessment of the voltage support capability of the new energy power station.

6. The method for quantitatively evaluating the voltage support capability of new energy power plants according to claim 2, characterized in that, The evaluation index of the voltage support capability of the grid-connected single unit Γ GFL The formula for calculating (s) is: ； In the formula, ∆Q e_L To track the change in reactive power output of grid-connected renewable energy, ∆U t U represents the change in port voltage during reactive power disturbance. c0_L To determine the steady-state value of the internal potential of the grid-connected unit, U t0 X is the steady-state value of the port voltage. f_L For the filter reactance of the grid-connected unit, k up k is the proportional parameter of the outer loop PI controller for the terminal voltage. ui The integral parameters of the outer loop PI controller for the terminal voltage; The evaluation index of the voltage support capability of the network-type single unit Γ GFM The formula for calculating (s) is: ； In the formula, ∆Q e_M ∆U represents the change in reactive power output of grid-type energy storage. t U represents the change in port voltage during reactive power disturbance. c0_M U is the steady-state value of the internal potential of a grid-connected unit. t0 X is the steady-state value of the port voltage. f_M For the filter reactor of the grid-type unit, D q is the reactive power-voltage droop coefficient, and K is the reactive power loop integral coefficient.

7. The method for quantitatively evaluating the voltage support capability of new energy power plants according to claim 1, characterized in that, The standardized overall voltage support capability evaluation index Γ(s) for the new energy power station is: ； In the formula, n represents the number of grid-connected new energy generating units, and Γ GFL (s) is an evaluation index for the voltage support capability of a single unit in grid-connected new energy vehicles. GFL To match the rated capacity of a single unit in grid-connected new energy vehicles, S N m represents the rated capacity of the new energy power plant; m represents the number of grid-connected energy storage units; Γ represents the rated capacity of the new energy power plant. GFM (s) is an evaluation index for the voltage support capability of a single unit in a grid-type energy storage system. GFM This refers to the rated capacity of a single unit in a grid-type energy storage system. The voltage support capability assessment index at the grid connection point Γ PCC The formula for calculating (s) is: ； In the formula, Γ(s) is the evaluation index of the overall voltage support capability of new energy power plants after standardization, and X T For the leakage reactance of the step-up transformer in the new energy power plant, S N For the rated capacity of new energy power plants, S T X is the rated capacity of the step-up transformer. g It is the equivalent reactance of the power grid.

8. A device for quantitatively evaluating the voltage support capability of a new energy power station, characterized in that, The device includes: The single-unit evaluation index acquisition module is used to acquire the control parameters and circuit parameters of grid-connected and grid-connected units, and based on the control parameters and circuit parameters, determine the single-unit voltage support capability evaluation index of grid-connected new energy and grid-connected energy storage. The overall evaluation index acquisition module is used to determine the overall voltage support capability evaluation index of the new energy power station by taking the rated capacity of the new energy power station as the benchmark, combining the capacity ratio of different types of units in the power station, integrating the single unit voltage support capability evaluation index, and determining the overall voltage support capability evaluation index of the new energy power station. The grid connection point assessment index acquisition module is used to calculate the overall voltage support capability assessment index based on the step-up transformer parameters and the grid equivalent impedance, and determine the voltage support capability assessment index of the new energy power station at the grid connection point. The quantitative assessment module is used to quantitatively assess the voltage support capability of new energy power plants based on the amplitude-frequency characteristics of the voltage support capability assessment index at the grid connection point.

9. An electronic device, characterized in that, include: At least one processor; And a memory that stores instructions that, when executed by the at least one processor, cause the at least one processor to perform the quantitative evaluation method for the voltage support capability of new energy power plants as described in any one of claims 1 to 7.

10. A machine-readable storage medium, characterized in that, It stores executable instructions that, when executed, cause the machine to perform the quantitative evaluation method for the voltage support capability of new energy power plants as described in any one of claims 1 to 7.

Images