Method and device for determining safety margin of frequency converter station in wind power low-frequency transmission system
Patent Information
- Application Number
- CN202610543977.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-23
- Publication Date
- 2026-10-23
AI Technical Summary
建模精度不足：多数方法未充分考虑新能源高阶不确定性的时空相关性，导致安全域边界计算偏差较大
根据预先构建的新能源场站与变频站的等效模型以及预设约束条件确定变频站的安全域；
Smart Images
Figure CN122968905A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of new energy technology, specifically to a method and apparatus for determining the safety margin of a frequency converter station in a wind power low-frequency transmission system. Background Technology
[0002] In the context of large-scale grid integration of new energy sources, low-frequency transmission systems are considered an important solution for long-distance wind power transmission due to their low impedance and high transmission capacity. However, compared with traditional power frequency AC systems, low-frequency wind power aggregation-conversion systems, i.e., low-frequency wind power transmission systems, differ in voltage stability mechanisms and power coupling characteristics, making it difficult to directly apply existing grid security domain calculation and evaluation methods.
[0003] In traditional AC systems, the voltage safety domain is typically obtained through power flow sensitivity analysis, PV curve analysis, or generalized Jacobian matrix characteristic analysis. The core assumption is that system node voltages are constrained by static power injection and are dominated by synchronous machines. However, in low-frequency wind power aggregation-conversion systems, there are no inertial-supported synchronous machines on the system side; voltage support is achieved by modular multilevel matrix converters (M3Cs) and droop control strategies. Its voltage stability characteristics are controlled by the combined effects of internal and external constraints of the converter station and the dynamic output of renewable energy units, causing the system's steady-state operating boundary to no longer satisfy the traditional linearization assumption. Under different wind farm outputs and converter station control parameters, the system may rapidly exceed the stability boundary, leading to voltage overshoot.
[0004] Despite the progress made by existing methods, the following significant limitations remain: Insufficient modeling accuracy: Most methods do not fully consider the spatiotemporal correlation of higher-order uncertainties in new energy sources, resulting in significant deviations in the calculation of the safety domain boundary. For example, existing machine learning feature selection methods rely on historical data and have weak generalization ability, making them difficult to adapt to extreme fluctuation scenarios.
[0005] Poor synergy in optimization objectives: Existing adaptive weighting models dynamically adjust the weights of objectives such as active power loss and voltage deviation, but ignore the conflict relationships between multiple objectives. Some source-load coordination strategies lack dynamic response mechanisms and cannot effectively cope with real-time fluctuations in source and load. Some methods rely on centralized decision-making for cluster voltage control, making it difficult to adapt to the decentralized characteristics of distributed power sources.
[0006] The stability margin is too simplistic: some methods only focus on the static boundary of the load safety domain control and ignore transient stability; the safety domain analysis does not coordinate voltage stability and frequency stability; although the integrated assessment couples power angle and voltage margin, it does not extend to static / transient coordinated scenarios.
[0007] Low computational efficiency: Existing two-stage optimization models are limited by the large-scale computation of second-order cone optimization; existing active learning requires multiple calls to time-domain simulation, which is time-consuming; although existing visualization methods reduce dimensionality, they still rely on iterative solutions of nonlinear network decomposition. Summary of the Invention
[0008] To address the problems in the prior art, embodiments of the present invention provide a method and apparatus for determining the safety margin of a frequency converter station in a wind power low-frequency transmission system, which can at least partially solve the problems existing in the prior art.
[0009] On the one hand, this invention proposes a method for determining the safety margin of a frequency converter station in a low-frequency wind power transmission system, including: The safety domain of the frequency converter station is determined based on the pre-constructed equivalent model of the new energy power station and the frequency converter station, as well as the preset constraints. The influencing factors of the safety domain are determined, and the influencing factors are used as independent variables for calculating the safety margin of the frequency converter. The safety margin of the frequency converter is determined based on the shortest distance from the operating point to the safety domain.
[0010] The equivalent model includes the voltage, active power, and reactive power at the grid connection point; correspondingly, determining the safety domain of the frequency converter station based on the pre-constructed equivalent model of the new energy power station and the frequency converter station, as well as preset constraints, includes: Using the active power and reactive power of the grid connection point as a two-dimensional plane, and the voltage of the grid connection point as the height perpendicular to the two-dimensional plane, the safety domain is obtained by applying parameter constraints through the preset constraint conditions.
[0011] The preset constraints are obtained by taking the intersection of the frequency converter station capacity constraints, frequency converter station current constraints, frequency converter station transformer ratio constraints, system voltage constraints, new energy power station operating range constraints, and system power flow equation constraints.
[0012] The factors influencing the determination of the security domain include: The active power, reactive power, bus voltage, and converter ratio of the frequency converter station are identified as the influencing factors.
[0013] Wherein, the operating point includes the reactive power operating point of the frequency converter station; correspondingly, the step of using the influencing factors as independent variables in calculating the safety margin of the frequency converter station, and determining the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain, includes: Determine the current active power profile of the safety domain, obtain the shortest distance from the reactive power operating point to the boundary of the safety domain on the current active power profile, and calculate the dynamic reactive power margin of the frequency converter station based on the shortest distance and the independent variable.
[0014] Wherein, the operating point includes the voltage of the grid connection point; correspondingly, the step of using the influencing factors as independent variables in calculating the safety margin of the frequency converter station, and determining the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain, includes: Obtain the first and second limit voltage values, calculate the first voltage distance between the voltage at the grid connection point and the first limit voltage value, and the second voltage distance between the voltage at the grid connection point and the second limit voltage value, and calculate the low-frequency side voltage safety margin of the frequency converter station based on the smaller of the first and second voltage distances and the independent variable.
[0015] On one hand, the present invention proposes a safety margin determination device for a frequency converter station in a wind power low-frequency transmission system, comprising: The first determining unit is used to determine the safety domain of the frequency converter station based on the pre-constructed equivalent model of the new energy power station and the frequency converter station and the preset constraints. The second determining unit is used to determine the influencing factors of the safety domain, use the influencing factors as independent variables for calculating the safety margin of the frequency converter, and determine the safety margin of the frequency converter based on the shortest distance from the operating point to the safety domain.
[0016] In another aspect, embodiments of the present invention provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the following method: The safety domain of the frequency converter station is determined based on the pre-constructed equivalent model of the new energy power station and the frequency converter station, as well as the preset constraints. The influencing factors of the safety domain are determined, and the influencing factors are used as independent variables for calculating the safety margin of the frequency converter. The safety margin of the frequency converter is determined based on the shortest distance from the operating point to the safety domain.
[0017] This invention provides a computer-readable storage medium, comprising: The computer-readable storage medium stores a computer program that, when executed by a processor, implements the following method: The safety domain of the frequency converter station is determined based on the pre-constructed equivalent model of the new energy power station and the frequency converter station, as well as the preset constraints. The influencing factors of the safety domain are determined, and the influencing factors are used as independent variables for calculating the safety margin of the frequency converter. The safety margin of the frequency converter is determined based on the shortest distance from the operating point to the safety domain.
[0018] This invention also provides a computer program product, which includes a computer program that, when executed by a processor, implements the following method: The safety domain of the frequency converter station is determined based on the pre-constructed equivalent model of the new energy power station and the frequency converter station, as well as the preset constraints. The influencing factors of the safety domain are determined, and the influencing factors are used as independent variables for calculating the safety margin of the frequency converter. The safety margin of the frequency converter is determined based on the shortest distance from the operating point to the safety domain.
[0019] The method and apparatus for determining the safety margin of a frequency converter station in a low-frequency wind power transmission system provided in this invention determine the safety domain of the frequency converter station based on a pre-constructed equivalent model of the new energy power plant and the frequency converter station, as well as preset constraints; determine the influencing factors of the safety domain, use the influencing factors as independent variables for calculating the safety margin of the frequency converter station, and determine the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain, which helps to identify out-of-bounds risks in advance, thereby improving the safety and reliability of system operation. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. 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. In the drawings: Figure 1 This is a flowchart illustrating a method for determining the safety margin of a frequency converter station in a wind power low-frequency transmission system according to an embodiment of the present invention.
[0021] Figure 2 This is a schematic diagram illustrating the security domain of a frequency converter station provided in an embodiment of the present invention.
[0022] Figure 3 This is a schematic diagram illustrating the current active power profile of the safety domain of a frequency converter station provided in an embodiment of the present invention.
[0023] Figure 4 This is a schematic diagram of the safety margin determination device for the frequency converter station in a wind power low-frequency transmission system provided by an embodiment of the present invention.
[0024] Figure 5 This is a schematic diagram of the physical structure of a computer device provided in an embodiment of the present invention. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.
[0026] Figure 1 This is a flowchart illustrating a method for determining the safety margin of a frequency converter station in a wind power low-frequency transmission system according to an embodiment of the present invention. Figure 1 As shown in the embodiments of the present invention, the method for determining the safety margin of the frequency converter station in a wind power low-frequency transmission system includes: Step S1: Determine the safety domain of the frequency converter station based on the pre-constructed equivalent model of the new energy power station and the frequency converter station, as well as the preset constraints.
[0027] Step S2: Determine the influencing factors of the safety domain, use the influencing factors as the independent variables for calculating the safety margin of the frequency converter, and determine the safety margin of the frequency converter based on the shortest distance from the operating point to the safety domain.
[0028] In step S1 above, the device determines the safety domain of the frequency converter station based on a pre-constructed equivalent model of the new energy power station and the frequency converter station, as well as preset constraints. The device can be a computer device executing this method. The acquisition, storage, use, and processing of data in this application's technical solution all comply with relevant regulations. The construction of the equivalent model of the new energy power station and the frequency converter station is explained below: The low-frequency side renewable energy power station is equivalent to an equivalent power source P. S +jQ S The equivalent impedance Z of the collecting line and the sending line S It can be expressed by the following formula:
[0029] in, For the network loss of new energy power stations, The voltage at the grid connection point, The active power at the grid connection point. The reactive power at the grid connection point, ( v This indicates conjugate. Under different wind farm output conditions, the system network loss varies, resulting in different equivalent impedances.
[0030] The safety domain of a frequency converter station is its safe steady-state operating region. This safety domain is depicted on a two-dimensional plane with active power on the horizontal axis and reactive power on the vertical axis. It is obtained by taking the intersection of the frequency converter station capacity constraints, frequency converter station current constraints, frequency converter station turns ratio constraints, system voltage constraints, new energy power plant operating range constraints, and system power flow equation constraints. If the frequency converter station bus voltage U at a certain moment... M3C Given that the power flowing into the frequency converter station is P M3C +jQ M3C Therefore, the operating range of the new energy low-frequency collection system should meet the following constraints: Variable frequency drive (VFD) station capacity constraints:
[0031] Among them, S M3CN For the rated capacity of the frequency converter station, P M3C Q represents the active power of the frequency converter station. M3C This represents the reactive power of the frequency converter station.
[0032] Frequency converter station current constraints:
[0033] in, is the rated current of the frequency converter station, and k is the converter ratio of the frequency converter station.
[0034] Frequency converter ratio constraints:
[0035] in, This represents the minimum commutator transformer ratio. This represents the maximum value of the converter transformer ratio.
[0036] System voltage constraints:
[0037] in, The minimum system voltage can be selected as 0.97. This represents the maximum system voltage; 1.07 can be selected. This refers to the bus voltage of the new energy power station. For low-frequency transformer bus voltage, and All should meet the preset upper and lower voltage limits.
[0038] Operating range constraints for new energy power stations:
[0039] in, For the total reactive power output of new energy power plants, The minimum total reactive power output of the new energy power station This represents the maximum total reactive power output of the new energy power station. Always contributing to the development of new energy power plants For the minimum total active power output of the new energy power station, This represents the maximum total active power output of the renewable energy power station. This is because the active power capacity and reactive power compensation configuration of renewable energy power stations are both limited.
[0040] System power flow equation constraints:
[0041] Where Pi and Qi represent the injected active power and reactive power at node i, respectively, Ui represents the voltage value at node i, and G ij B ij Let i and j represent the branch conductance and branch susceptance, respectively. This represents the phase angle difference between node i and node j. For example... Figure 2 As shown, the red part represents the safety domain, and the pentagram indicates the voltage value at the grid connection point when the maximum safe steady-state operating region is achieved.
[0042] In step S2 above, the device determines the influencing factors of the safety domain, uses these influencing factors as independent variables for calculating the safety margin of the frequency converter, and determines the safety margin of the frequency converter based on the shortest distance from the operating point to the safety domain. Determining the influencing factors of the safety domain includes: The active power, reactive power, bus voltage, and converter ratio of the frequency converter station are identified as the influencing factors.
[0043] According to Z S As can be seen from the formula, Z S With the network loss of new energy power stations P loss +jQ loss Related to, and thus to, the total power output P of the new energy power station. s +jQ s Therefore, the impact analysis of the total power output of the new energy power station on the safe steady-state operation area of the frequency converter can be transformed into the impact of the equivalent line impedance Zs on the safe steady-state operation area.
[0044] According to Z S As can be seen from the formula, Z S It is not an independent constant, but rather is determined by the grid loss of the new energy power station and the voltage U at the grid connection point. pcc The power output at the grid connection point and the total power output of the renewable energy power station are both determined by these factors; and these factors are in turn influenced by the total power output P of the renewable energy power station. s +jQ sTherefore, the impact of the total power output of the new energy power station on the safe steady-state operation range of the frequency converter can be equivalent to the impact of the change in equivalent impedance Zs under different operating conditions on the safe steady-state operation range.
[0045] As the equivalent impedance increases, the safe steady-state operating region gradually decreases. This indicates that the magnitude of the equivalent impedance, i.e., the power output of the renewable energy power plant, has a significant impact on the safe steady-state operating region. Simultaneously, it also shows that when the internal line impedance of the renewable energy power plant is high, the safe steady-state operating region of the frequency converter station is a crucial factor limiting the power transmission from the renewable energy power plant. Since the active and reactive power of the frequency converter station are closely related to the total power of the renewable energy power plant, the active and reactive power of the frequency converter station can be considered as influencing factors of the safe operating region.
[0046] As the voltage setpoint at the grid connection point increases, the shape of the safe and stable region changes significantly, affecting the reactive power regulation margin of the frequency converter station during operation. For example... Figure 2 As shown in the 3D graph, the impact of the grid connection point voltage on the safe steady-state operating range can be more intuitively seen from the variation of the grid connection point voltage (0.97, 1.03). The safe steady-state operating range reaches its maximum at a certain voltage value; increasing or decreasing the voltage from this origin will decrease the safe steady-state operating range. Since there is a correlation between the inverter station bus voltage and the grid connection point voltage setpoint, the inverter station bus voltage can be considered as an influencing factor on the safety domain.
[0047] Fixed equivalent impedance Zs and grid connection point voltage setting U pcc By changing the converter transformer's speed range, the safe steady-state operating region can be obtained under different conditions. As the converter transformer's speed range changes, the shape and size of the safe steady-state operating region undergo slight changes, while its relative position on the power two-dimensional coordinate axis changes significantly. Intuitively, this is because when the converter transformer's speed range changes, the reactive power distribution of the system changes, thus shifting the position of the safe steady-state operating region vertically. Therefore, the setting of the converter transformer's speed range is quite important for safe steady-state operation. This means that the converter transformer ratio of the frequency converter station is also considered as an influencing factor on the safety domain.
[0048] The operating point includes the reactive power operating point of the frequency converter station; correspondingly, the step of using the influencing factors as independent variables in calculating the safety margin of the frequency converter station, and determining the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain, includes: Determine the current active power profile of the safety domain, obtain the shortest distance from the reactive power operating point to the boundary of the safety domain on the current active power profile, and calculate the dynamic reactive power margin of the frequency converter station based on the shortest distance and the independent variable.
[0049] The operating point includes the voltage of the grid connection point; correspondingly, the step of using the influencing factors as independent variables in calculating the safety margin of the frequency converter station, and determining the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain, includes: Obtain the first and second limit voltage values, calculate the first voltage distance between the voltage at the grid connection point and the first limit voltage value, and the second voltage distance between the voltage at the grid connection point and the second limit voltage value, and calculate the low-frequency side voltage safety margin of the frequency converter station based on the smaller of the first and second voltage distances and the independent variable.
[0050] Variable frequency drives (VFDs) are characterized by rapid reactive power regulation. The grid connection point voltage setting essentially determines the voltage level of each busbar within the renewable energy power plant. Therefore, ensuring reliable and safe reactive power voltage support from the VFD during operation is essential. This invention proposes two indicators to determine the safety margin of the VFD: dynamic reactive power margin and grid connection point voltage safety margin (i.e., low-frequency side voltage safety margin). The dynamic reactive power margin measures the amount of reactive power that the VFD can still handle, while the grid connection point voltage safety margin measures the margin for voltage instability at the VFD's grid connection point and reflects the voltage levels of each busbar within the renewable energy power plant.
[0051] like Figure 3 As shown, the dynamic reactive power margin of the frequency converter station is the shortest distance from the reactive power operating point of the frequency converter station to the safe steady-state operating boundary under the current active power section. Furthermore, since the safe steady-state operating region is related to the frequency converter station bus voltage U... M3C It is related to the converter transformer ratio k, therefore its dynamic reactive power margin is related to U. M3C The function of k and operating power is shown in the following equation: .
[0052] The grid connection point voltage setting changes the shape and size of the safe steady-state operating region; therefore, changing the grid connection point voltage alters the relative position of the current grid connection voltage point to the safe steady-state operating region. If the grid connection point voltage setting is too high or too low, the current grid connection voltage point may even exceed the safe steady-state operating region. Similarly, a first limit voltage value U can be obtained. pcc1 (Maximum or minimum grid connection point voltage) and second limiting voltage value U pcc2 (The minimum or maximum voltage at the grid connection point) The distance between the current grid connection voltage point and the first limit voltage value is denoted as dU1, and the distance between the current grid connection voltage point and the second limit voltage value is denoted as dU2.
[0053] Therefore, the voltage safety margin F at the grid connection point UThe shortest distance from the current grid-connected voltage point to the limit voltage value is shown in the following formula: .
[0054] The method for determining the safety margin of the frequency converter station in the wind power low-frequency transmission system provided in this embodiment of the invention is further explained below: (1) Construction of equivalent model of new energy power station-frequency converter station: In the low-frequency side collection system, the output of multiple new energy power stations is combined into an equivalent power source; at the same time, the collection line and the transmission line are equivalent to impedance as a whole. This impedance can be calculated based on the system network loss and bus voltage, and is adjusted with the change of wind power output. The frequency converter station model is composed of its rated capacity, transformation ratio, bus voltage setpoint and other parameters. Thus, a unified model of "equivalent power source - equivalent impedance - frequency converter station" is established, which provides a basis for security domain analysis.
[0055] (2) Definition of Constraints for Safe Steady-State Operation Region: Based on the above model, the power-reactive power region for safe operation of the frequency converter station is defined and limited by various constraints. The constraints include the frequency converter station capacity, current, transformer ratio, bus voltage, station output range, and system power flow balance. The constraints together determine the set of feasible operating points of the frequency converter station on the active-reactive power plane, i.e., the safe steady-state operation region. This region describes all states in which the frequency converter station can operate stably under the conditions of satisfying electrical and control boundary conditions.
[0056] (3) Analysis of factors affecting the safe steady-state operation zone: The study of the impact of different operating conditions on the safe zone can reveal the coupling relationship between system parameters and safe operating range, providing a basis for operation optimization.
[0057] (4) Safety margin index and boundary judgment method: In order to quantitatively assess the safety level of the system, a dynamic reactive power margin is proposed. and voltage safety margin The former reflects the reactive power margin that the current frequency converter can continue to adjust, while the latter measures the margin between the current voltage and the limit voltage. Both can be obtained from the distance between the operating point and the safety domain boundary, and are used to determine whether the system is approaching the instability boundary, and to provide a quantitative reference for scheduling and control decisions.
[0058] (5) Safety Domain Calculation and Result Application: After determining the model and constraints, the safety domain is numerically calculated. The operating point that satisfies the constraints is obtained by traversal or optimization algorithms, and the safety domain boundary on the power-reactive power plane is plotted. Combined with changes in parameters such as voltage and transformer ratio, a three-dimensional safety domain diagram can be generated to visualize the operating status. Reactive power / voltage indicators are used for online monitoring and early warning; when any indicator is lower than the set threshold, the operating system can automatically adjust the power, reactive power, or voltage settings to bring the operating point back to the safe zone, thereby ensuring the long-term safe and stable operation of the low-frequency wind power collection and transmission-frequency conversion system.
[0059] The method provided by this invention has the following advantages: This invention effectively fills the gap in traditional security domain analysis for this special system structure by establishing a calculation model of the safe steady-state operation region of the frequency converter station in the "low-frequency wind power collection and transmission-frequency conversion system". First, the model statically equates physical elements such as new energy power stations and transmission lines to power sources and impedance forms.
[0060] Secondly, this invention integrates the internal control constraints of the frequency converter station with the power / voltage constraints of the low-frequency network side into the solution of the safety domain boundary, thereby enhancing the engineering feasibility of boundary identification.
[0061] Finally, margin indicators (such as dynamic reactive power margin and voltage safety margin) provide operation monitoring and early warning functions, which help to identify out-of-bounds risks in advance and improve the safety and reliability of system operation.
[0062] In summary, the method of this invention combines theoretical rigor with operability, and significantly improves the safe operation guarantee capability of low-frequency wind power collection-frequency conversion and transmission systems.
[0063] Within the existing large-scale renewable energy power plant transmission systems, a "renewable energy island" system structure based on low-frequency aggregation and frequency conversion transmission is under development. This system is characterized by: the low-frequency sending end consisting of multiple wind farms and other renewable energy plants forming a long-term operating island system, designed to be decoupled from the AC main grid during daily operation; within this system, all wind power output is aggregated to the low-frequency bus, transmitted over long distances via the switching station, and finally transmitted to the load or main grid via the receiving-end frequency converter station, while local load is minimal or near zero. This structure is fundamentally different from traditional large-scale renewable energy grid-connected systems and traditional AC transmission systems.
[0064] In this system, the frequency converter station plays a crucial role, providing voltage / frequency support for the low-frequency island and transmitting the collected renewable energy output through frequency converters. The safe steady-state operating region of the frequency converter station directly restricts the upper limit of the power output of the renewable energy island system, the overall stability margin of the system, and its disturbance rejection capability. Therefore, for this type of system, it is urgent to accurately characterize the safe steady-state operating region of the frequency converter station in islanded mode (i.e., the power, reactive power, and voltage combination conditions allowed by the frequency converter station and its supporting systems) and study its influencing factors, so as to serve as an important basis for the optimal control of reactive power and voltage and the maximization of power output in the renewable energy island. Based on the above, this invention aims to solve the following technical problem: under the low-frequency power transmission structure of renewable energy islands, how to construct a safe domain calculation model applicable to the safe steady-state operation of the frequency converter station, that is, to clearly define the boundary of the region where the frequency converter station is still in a safe and operable state under given operating conditions (collected power output, reactive power injection, low-frequency bus voltage, and frequency converter station control parameters).
[0065] By solving the above-mentioned technical problems, this invention will provide a system-level, safe, quantifiable, and visualized safety domain calculation method for low-frequency wind power collection-conversion transmission systems, providing technical support for frequency converter station operation strategy design, output decision-making, and reactive power / voltage control optimization, thereby improving the system's safe operation guarantee capability and economic operation capability.
[0066] The method for determining the safety margin of the frequency converter station in a wind power low-frequency transmission system provided in this invention has the following beneficial technical effects: This invention establishes a safe steady-state operating domain model suitable for low-frequency wind power collection and transmission-conversion systems, achieving a quantitative definition of the operable power-reactive power combination of the frequency converter station, thereby significantly improving the system's operational safety and controllability. First, this scheme statically equates the power output, lines, and collection network on the islanded side of the renewable energy source to power sources and equivalent impedances, and combines frequency converter station control constraints with network constraints, making the safety domain boundary calculable and visualized at the engineering level, improving the accuracy of boundary identification. Second, it introduces margin indicators (such as dynamic reactive power margin and voltage safety margin), enabling the system's operating status to be quantified in real time as "current position - boundary distance," thus supporting control decisions such as operational early warning, power output limitation, and reactive power compensation adjustment. Third, this scheme adapts to new transmission structures that operate under long-term islanded and low-frequency decoupled operation, filling the blind spots of traditional power frequency safety domain analysis, and is specifically designed for low-frequency frequency converter systems, enhancing its applicability and engineering feasibility. Ultimately, through security domain calculation and online monitoring mechanisms, this invention improves the power utilization, safety margin, and operational reliability of the new energy aggregation-frequency conversion transmission system, which helps to achieve safe and stable operation under large-scale and high-proportion access of new energy.
[0067] The method for determining the safety margin of a frequency converter station in a low-frequency wind power transmission system provided in this invention determines the safety domain of the frequency converter station based on a pre-constructed equivalent model of the new energy power plant and the frequency converter station, as well as preset constraints; it determines the influencing factors of the safety domain, uses the influencing factors as independent variables for calculating the safety margin of the frequency converter station, and determines the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain. This method helps to identify out-of-bounds risks in advance, thereby improving the safety and reliability of system operation.
[0068] In the above optional embodiments, the equivalent model includes the voltage at the grid connection point, the active power at the grid connection point, and the reactive power at the grid connection point; correspondingly, determining the safety domain of the frequency converter station based on the pre-constructed equivalent model of the new energy power station and the frequency converter station and preset constraints includes: Using the active power and reactive power of the grid connection point as a two-dimensional plane, and the voltage of the grid connection point as the height perpendicular to the two-dimensional plane, the safety domain is obtained by applying the preset constraint conditions. This can be referred to the above embodiment for further explanation and will not be repeated here.
[0069] In the above optional embodiments, the preset constraints are obtained by taking the intersection of the frequency converter station capacity constraints, frequency converter station current constraints, frequency converter station transformer ratio constraints, system voltage constraints, new energy power station operating range constraints, and system power flow equation constraints. This can be referred to the above embodiments for further explanation and will not be repeated here.
[0070] In the above optional embodiments, determining the influencing factors of the security domain includes: The active power, reactive power, bus voltage, and converter transformer ratio of the frequency converter station are identified as the influencing factors. This can be referred to the above embodiments for further explanation and will not be repeated here.
[0071] In the above optional embodiments, the operating point includes the reactive power operating point of the frequency converter station; correspondingly, the step of using the influencing factors as the independent variable for calculating the safety margin of the frequency converter station, and determining the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain, includes: The current active power profile of the safety domain is determined. The shortest distance from the reactive power operating point to the boundary of the safety domain is obtained on the current active power profile. The dynamic reactive power margin of the frequency converter station is calculated based on the shortest distance and the independent variable. This can be referred to the above embodiment for further explanation and will not be repeated here.
[0072] In the above optional embodiments, the operating point includes the voltage of the grid connection point; correspondingly, the step of using the influencing factors as the independent variable in calculating the safety margin of the frequency converter, and determining the safety margin of the frequency converter based on the shortest distance from the operating point to the safety domain, includes: Obtain the first and second limiting voltage values, calculate the first voltage distance between the grid connection point voltage and the first limiting voltage value, and the second voltage distance between the grid connection point voltage and the second limiting voltage value. Based on the smaller of the first and second voltage distances, and the independent variable, calculate the low-frequency side voltage safety margin of the frequency converter station. Refer to the above embodiment for further details.
[0073] Figure 4 This is a schematic diagram of the safety margin determination device for a frequency converter station in a wind power low-frequency transmission system according to an embodiment of the present invention, as shown below. Figure 4 As shown, the safety margin determination device for the frequency converter station in the wind power low-frequency transmission system provided in this embodiment of the invention includes a first determination unit 401 and a second determination unit 402, wherein: The first determining unit 401 is used to determine the safety domain of the frequency converter station based on the pre-constructed equivalent model of the new energy power station and the frequency converter station and the preset constraints; the second determining unit 402 is used to determine the influencing factors of the safety domain, use the influencing factors as the independent variables for calculating the safety margin of the frequency converter station, and determine the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain.
[0074] Specifically, the first determining unit 401 in the device is used to determine the safety domain of the frequency converter station based on the pre-constructed equivalent model of the new energy power station and the frequency converter station and the preset constraints; the second determining unit 402 is used to determine the influencing factors of the safety domain, use the influencing factors as the independent variables for calculating the safety margin of the frequency converter station, and determine the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain.
[0075] The safety margin determination device for frequency converter stations in wind power low-frequency transmission systems provided in this invention determines the safety domain of the frequency converter station based on a pre-constructed equivalent model of the new energy power plant and the frequency converter station, as well as preset constraints; it determines the influencing factors of the safety domain, uses the influencing factors as independent variables for calculating the safety margin of the frequency converter station, and determines the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain. This helps to identify out-of-bounds risks in advance, thereby improving the safety and reliability of system operation.
[0076] The embodiments of the present invention provide a safety margin determination device for frequency converter stations in wind power low-frequency transmission systems. Specifically, it can be used to execute the processing flow of the above-described method embodiments. Its functions will not be repeated here, but can be referred to the detailed description of the above-described method embodiments.
[0077] Figure 5 This is a schematic diagram of the physical structure of a computer device provided in an embodiment of the present invention, such as... Figure 5As shown, the computer device includes: a memory 501, a processor 502, and a computer program stored in the memory 501 and executable on the processor 502. When the processor 502 executes the computer program, it implements the following method: The safety domain of the frequency converter station is determined based on the pre-constructed equivalent model of the new energy power station and the frequency converter station, as well as the preset constraints. The influencing factors of the safety domain are determined, and the influencing factors are used as independent variables for calculating the safety margin of the frequency converter. The safety margin of the frequency converter is determined based on the shortest distance from the operating point to the safety domain.
[0078] This embodiment discloses a computer program product, which includes a computer program that, when executed by a processor, implements the following method: The safety domain of the frequency converter station is determined based on the pre-constructed equivalent model of the new energy power station and the frequency converter station, as well as the preset constraints. The influencing factors of the safety domain are determined, and the influencing factors are used as independent variables for calculating the safety margin of the frequency converter. The safety margin of the frequency converter is determined based on the shortest distance from the operating point to the safety domain.
[0079] This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the following method: The safety domain of the frequency converter station is determined based on the pre-constructed equivalent model of the new energy power station and the frequency converter station, as well as the preset constraints. The influencing factors of the safety domain are determined, and the influencing factors are used as independent variables for calculating the safety margin of the frequency converter. The safety margin of the frequency converter is determined based on the shortest distance from the operating point to the safety domain.
[0080] Compared with existing technical solutions, the method for determining the safety margin of a frequency converter station in a low-frequency wind power transmission system provided by this invention determines the safety domain of the frequency converter station based on a pre-constructed equivalent model of the new energy power plant and the frequency converter station, as well as preset constraints; it determines the influencing factors of the safety domain, uses the influencing factors as independent variables for calculating the safety margin of the frequency converter station, and determines the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain. This helps to identify out-of-bounds risks in advance, thereby improving the safety and reliability of system operation.
[0081] 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.
[0082] This 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, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.
[0083] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.
[0084] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0085] In the description of this specification, the references to terms such as "an embodiment," "a specific embodiment," "some embodiments," "for example," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0086] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for determining the safety margin of a frequency converter station in a low-frequency wind power transmission system, characterized in that, include: The safety domain of the frequency converter station is determined based on the pre-constructed equivalent model of the new energy power station and the frequency converter station, as well as the preset constraints. The influencing factors of the safety domain are determined, and the influencing factors are used as independent variables for calculating the safety margin of the frequency converter. The safety margin of the frequency converter is determined based on the shortest distance from the operating point to the safety domain.
2. The method for determining the safety margin of the frequency converter station in a wind power low-frequency transmission system according to claim 1, characterized in that, The equivalent model includes the voltage, active power, and reactive power at the grid connection point; correspondingly, determining the safety domain of the frequency converter station based on the pre-constructed equivalent model of the new energy power station and the frequency converter station, as well as preset constraints, includes: Using the active power and reactive power of the grid connection point as a two-dimensional plane, and the voltage of the grid connection point as the height perpendicular to the two-dimensional plane, the safety domain is obtained by applying parameter constraints through the preset constraint conditions.
3. The method for determining the safety margin of the frequency converter station in a wind power low-frequency transmission system according to claim 2, characterized in that, The preset constraints are obtained by taking the intersection of the following constraints: frequency converter station capacity constraint, frequency converter station current constraint, frequency converter station transformer ratio constraint, system voltage constraint, new energy power station operating range constraint, and system power flow equation constraint.
4. The method for determining the safety margin of the frequency converter station in a wind power low-frequency transmission system according to claim 1, characterized in that, The factors influencing the determination of the security domain include: The active power, reactive power, bus voltage, and converter ratio of the frequency converter station are identified as the influencing factors.
5. The method for determining the safety margin of the frequency converter station in a wind power low-frequency transmission system according to claim 1, characterized in that, The operating point includes the reactive power operating point of the frequency converter station; correspondingly, the step of using the influencing factors as independent variables in calculating the safety margin of the frequency converter station, and determining the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain, includes: Determine the current active power profile of the safety domain, obtain the shortest distance from the reactive power operating point to the boundary of the safety domain on the current active power profile, and calculate the dynamic reactive power margin of the frequency converter station based on the shortest distance and the independent variable.
6. The method for determining the safety margin of the frequency converter station in a wind power low-frequency transmission system according to claim 1, characterized in that, The operating point includes the voltage of the grid connection point; correspondingly, the step of using the influencing factors as independent variables in calculating the safety margin of the frequency converter station, and determining the safety margin of the frequency converter station based on the shortest distance from the operating point to the safety domain, includes: Obtain the first and second limit voltage values, calculate the first voltage distance between the voltage at the grid connection point and the first limit voltage value, and the second voltage distance between the voltage at the grid connection point and the second limit voltage value, and calculate the low-frequency side voltage safety margin of the frequency converter station based on the smaller of the first and second voltage distances and the independent variable.
7. A device for determining the safety margin of a frequency converter station in a low-frequency wind power transmission system, characterized in that, include: The first determining unit is used to determine the safety domain of the frequency converter station based on the pre-constructed equivalent model of the new energy power station and the frequency converter station and the preset constraints. The second determining unit is used to determine the influencing factors of the safety domain, use the influencing factors as independent variables for calculating the safety margin of the frequency converter, and determine the safety margin of the frequency converter based on the shortest distance from the operating point to the safety domain.
8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method of any one of claims 1 to 6.
9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method of any one of claims 1 to 6.
10. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the method of any one of claims 1 to 6.