Bridge arm reactor current calculation method and system based on flexible DC power transmission system

Abstract

The invention discloses a bridge arm reactor current calculation method and system based on a flexible direct current power transmission system, which is applied to the technical field of flexible direct current power transmission, and comprises the following steps: obtaining steady-state parameter data and topological structure parameter data of a target flexible direct current power transmission system; obtaining fault working condition parameter data of the bridge arm reactor; carrying out extraction processing on the topological structure parameter data to obtain equivalent circuit parameter data; processing the equivalent circuit parameter data by using a time domain analysis technology to obtain transient current data; inputting the steady-state parameter data and the transient current data into a current processing model for processing to obtain a transient peak current; performing simulation processing on the fault working condition parameter data of the bridge arm reactor to obtain an analogue simulation current; and obtaining a peak current based on the transient peak current and the analogue simulation current. According to the method provided by the invention, the technical problem that the current calculation of the existing bridge arm reactor is inaccurate can be solved, and the steady-state operation of the flexible direct-current power transmission system is ensured.

Description

Technical Field

[0001] This invention relates to the field of flexible DC transmission technology, and in particular to a method and system for calculating the current of bridge arm reactors based on a flexible DC transmission system. Background Technology

[0002] Flexible direct current transmission (VSC-HVDC), with its rapid controllability and flexible networking capabilities, has become a key supporting technology for the grid integration and consumption of new energy sources, power supply to isolated power grids, and cross-regional asynchronous interconnection. During a short-circuit fault on the DC side, the capacitors of the submodules in the flexible direct current transmission system form an instantaneous discharge loop through the fault point, causing the fault current to surge at the microsecond level. Meanwhile, the bridge arm reactors, through their inductive characteristics, can limit the rate of current change, preventing equipment damage due to overshoot.

[0003] In existing technologies, current is mostly measured directly using current sensors based on the Hall effect principle. Specifically, the sensor is installed near the bridge arm reactor and outputs an analog voltage signal proportional to the instantaneous current by sensing the surrounding magnetic field. This signal is sampled and quantized by an analog-to-digital converter and finally converted into a digital quantity that is read by the control system as a direct basis for the inner loop control, modulation and protection of the flexible DC transmission system.

[0004] However, the sensitivity and zero-point offset of Hall elements drift with changes in ambient temperature. Although high-end sensors have built-in temperature compensation circuits, they cannot achieve complete compensation in the event of rapid temperature changes or throughout the entire operating temperature range. This introduces time-varying measurement errors, which in turn lead to distortion of current feedback. Distorted current feedback will directly cause the controller to generate incorrect modulation commands, disrupting the decoupled control of active and reactive power, potentially causing system oscillations or even transient instability. Summary of the Invention

[0005] This invention provides a method and system for calculating the current of bridge arm reactors in a flexible DC transmission system, in order to solve the technical problem of inaccurate calculation of bridge arm reactor current in existing systems, and to ensure the steady-state operation of the flexible DC transmission system.

[0006] To address the aforementioned technical problems, this invention provides a method for calculating the current of a bridge arm reactor based on a flexible DC transmission system. The method includes: Acquire steady-state parameter data and topology parameter data of the target flexible DC transmission system; acquire fault condition parameter data of the bridge arm reactors in the target flexible DC transmission system; The equivalent circuit parameter data of the target flexible DC transmission system is obtained by extracting and processing the topology parameter data. The equivalent circuit parameter data is processed using time-domain analysis techniques to obtain transient current data; The steady-state parameter data and the transient current data are input into the constructed current processing model for processing to obtain the transient peak current of the bridge arm reactor. The fault condition parameter data of the bridge arm reactor are simulated to obtain the simulated current; The peak current of the bridge arm reactor is obtained based on the transient peak current and the simulated current.

[0007] As one preferred embodiment, the step of extracting and processing the topology parameter data to obtain the equivalent circuit parameter data of the target flexible DC transmission system includes: The topology parameter data is extracted and processed to obtain the basic circuit element parameters of the target flexible DC transmission system; The parameters of the basic circuit elements are processed using equivalent circuit simplification techniques to obtain the equivalent circuit parameter data of the target flexible DC transmission system.

[0008] As one preferred embodiment, the process of using time-domain analysis techniques to process the equivalent circuit parameter data to obtain transient current data includes: The equivalent circuit parameter data are processed using time-domain analysis techniques to obtain a mathematical model of the transient current components; The transient current component mathematical model is subjected to current superposition processing to obtain the transient current data.

[0009] As a preferred embodiment, the step of inputting the steady-state parameter data and the transient current data into the constructed current processing model for processing to obtain the transient peak current of the bridge arm reactor includes: The steady-state parameter data and the transient current data are correlated and filtered to obtain the time-domain sequence of the bridge arm current; The time-domain sequence of the bridge arm current is input into the current processing model constructed based on the principle of circuit transient response for processing to obtain the transient peak current.

[0010] As one preferred embodiment, the step of simulating the fault condition parameter data of the bridge arm reactor to obtain the simulated current includes: The fault condition parameter data of the bridge arm reactor are simulated to obtain simulated current waveform data; The simulated current waveform data is processed using a multi-fault-point traversal sampling and extraction technique to obtain the simulated current.

[0011] The present invention also provides a bridge arm reactor current calculation system based on a flexible DC transmission system, comprising: The acquisition module is used to acquire steady-state parameter data and topology parameter data of the target flexible DC transmission system; and to acquire fault condition parameter data of the bridge arm reactors in the target flexible DC transmission system. The extraction module is used to extract and process the topology parameter data to obtain the equivalent circuit parameter data of the target flexible DC transmission system; The analysis module is used to process the equivalent circuit parameter data using time-domain analysis techniques to obtain transient current data; The processing module is used to input the steady-state parameter data and the transient current data into the constructed current processing model for processing, so as to obtain the transient peak current of the bridge arm reactor. The simulation module is used to simulate the fault condition parameter data of the bridge arm reactor to obtain the simulated current. The generation module is used to obtain the peak current of the bridge arm reactor based on the transient peak current and the simulated current.

[0012] As one preferred embodiment, the step of extracting and processing the topology parameter data to obtain the equivalent circuit parameter data of the target flexible DC transmission system includes: The topology parameter data is extracted and processed to obtain the basic circuit element parameters of the target flexible DC transmission system; The parameters of the basic circuit elements are processed using equivalent circuit simplification techniques to obtain the equivalent circuit parameter data of the target flexible DC transmission system.

[0013] As one preferred embodiment, the process of using time-domain analysis techniques to process the equivalent circuit parameter data to obtain transient current data includes: The equivalent circuit parameter data are processed using time-domain analysis techniques to obtain a mathematical model of the transient current components; The transient current component mathematical model is subjected to current superposition processing to obtain the transient current data.

[0014] As a preferred embodiment, the step of inputting the steady-state parameter data and the transient current data into the constructed current processing model for processing to obtain the transient peak current of the bridge arm reactor includes: The steady-state parameter data and the transient current data are correlated and filtered to obtain the time-domain sequence of the bridge arm current; The time-domain sequence of the bridge arm current is input into the current processing model constructed based on the principle of circuit transient response for processing to obtain the transient peak current.

[0015] As one preferred embodiment, the step of simulating the fault condition parameter data of the bridge arm reactor to obtain the simulated current includes: The fault condition parameter data of the bridge arm reactor are simulated to obtain simulated current waveform data; The simulated current waveform data is processed using a multi-fault-point traversal sampling and extraction technique to obtain the simulated current.

[0016] Compared with the prior art, the beneficial effects of the present invention are at least one of the following: This invention acquires steady-state parameter data and topology parameter data of a target flexible DC transmission system; acquires fault condition parameter data of the bridge arm reactors in the target flexible DC transmission system; extracts and processes the topology parameter data to obtain equivalent circuit parameter data of the target flexible DC transmission system; processes the equivalent circuit parameter data using time-domain analysis technology to obtain transient current data; inputs the steady-state parameter data and the transient current data into a pre-constructed current processing model for processing to obtain the transient peak current of the bridge arm reactor; simulates the fault condition parameter data of the bridge arm reactor to obtain a simulated current; and obtains the peak current of the bridge arm reactor based on the transient peak current and the simulated current.

[0017] Compared with existing technologies, this invention obtains inherent parameters such as the system's steady-state condition, topology, and bridge arm reactor fault conditions, then extracts equivalent circuit parameters from the topology parameters, obtains transient current data through time-domain analysis, calculates the transient peak current by combining the steady-state parameter input current processing model, and obtains simulated current cross-validation through fault condition simulation. It replaces the distorted signal caused by temperature drift of the Hall sensor with accurate current calculation without temperature error. The entire process avoids system oscillation or transient instability, ensuring the steady-state operation of the flexible DC transmission system. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the method for calculating the current of a bridge arm reactor based on a flexible DC transmission system in one embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a bridge arm reactor current calculation system based on a flexible DC transmission system in one embodiment of the present invention; Figure label: The module consists of: 11. Acquisition module; 12. Extraction module; 13. Analysis module; 14. Processing module; 15. Simulation module; and 16. Generation module. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing specific embodiments only and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] One embodiment of the present invention provides a method for calculating the current of the bridge arm reactor in a flexible DC transmission system. For details, please refer to [link to relevant documentation]. Figure 1 , Figure 1 The diagram shown is a flowchart illustrating a method for calculating the current of a bridge arm reactor based on a flexible DC transmission system, according to one embodiment of the present invention. The method includes: S1: Obtain steady-state parameter data and topology parameter data of the target flexible DC transmission system; obtain fault condition parameter data of the bridge arm reactors in the target flexible DC transmission system; S2: Extract and process the topology parameter data to obtain the equivalent circuit parameter data of the target flexible DC transmission system; S3: The equivalent circuit parameter data is processed using time-domain analysis techniques to obtain transient current data; S4: Input the steady-state parameter data and the transient current data into the constructed current processing model for processing to obtain the transient peak current of the bridge arm reactor; S5: Simulate the fault condition parameter data of the bridge arm reactor to obtain the simulated current; S6: Based on the transient peak current and the simulated current, the peak current of the bridge arm reactor is obtained.

[0022] Specifically, steady-state parameter data refers to the key operating indicators and equipment rated parameters of the system under normal and stable operating conditions. These mainly include: rated DC voltage, rated DC current, rated transmission power, converter rated capacity, bridge arm reactor rated inductance, bridge arm submodule rated voltage and capacitance, as well as modulation ratio, firing angle, current loop steady-state setpoint, voltage loop steady-state setpoint, etc. during steady-state operation.

[0023] The topology parameter data describes the physical connection method and component structure characteristics of the target flexible DC transmission system, mainly including: system wiring method, converter topology type, number and connection method of bridge arms, self-inductance and mutual inductance values ​​of bridge arm reactors, capacitance values ​​of submodules, leakage inductance and magnetizing inductance values ​​of converter transformers, as well as the installation position of each bridge arm reactor in the converter, the connection sequence with submodules, and topology node information of current flow path, etc.

[0024] The fault condition parameter data addresses the fault scenarios that the bridge arm reactor may face, including fault type parameters, such as fault type and fault location; fault timing parameters, such as fault occurrence time, fault duration, fault clearing time, and system recovery and startup time after the fault; and fault boundary condition parameters, such as the system operating state just before the fault occurs.

[0025] In step S2, the equivalent circuit parameter data of the target flexible DC transmission system is obtained by extracting and processing the topology parameter data, including: extracting and processing the topology parameter data to obtain the basic circuit element parameters of the target flexible DC transmission system; and processing the basic circuit element parameters using equivalent circuit simplification techniques to obtain the equivalent circuit parameter data of the target flexible DC transmission system.

[0026] Specifically, based on the topology of the target flexible DC transmission system, the key basic components in the main circuit are identified, including bridge arm reactors, submodule capacitors, converter transformers, transmission lines, grounding components, etc.

[0027] For each identified component, its directly related electrical characteristic parameters are extracted from the topology parameter data. For example, the self-inductance characteristic parameters of the bridge arm reactor, the leakage inductance characteristic parameters of the converter transformer, the capacitance characteristic parameters of the submodule capacitor, the resistance and inductance characteristic parameters of the transmission line, and the resistance characteristic parameters of the grounding element are extracted from the topology parameters.

[0028] The extracted parameters are categorized and organized to form a complete set of basic circuit component parameters according to component type. Non-electrical characteristic parameters such as component installation position and connection sequence in the topology description are excluded to ensure that the extracted parameters are all core data reflecting the electrical function of the components.

[0029] Then, based on the calculation requirements for subsequent time-domain analysis, the simplification goals and accuracy requirements of the equivalent circuit are determined, clarifying the core electrical characteristics that need to be retained and the secondary characteristics that can be simplified. For example, if the focus is on transient current analysis, the characteristics of energy storage components such as inductors and capacitors can be retained first, while the secondary characteristics of loss components such as resistors can be reasonably simplified. Appropriate equivalent circuit simplification techniques are then selected to handle different types of component combinations and connection methods: for multiple series or parallel components of the same type, the series-parallel equivalent rule is used to integrate parameters, such as integrating multiple sub-module capacitors in the same bridge arm into a single equivalent capacitor parameter according to their connection method; for components with coupling relationships, such as multi-winding converter transformers, a decoupling equivalent method is used to transform them into uncoupled equivalent inductance parameters; for long-distance transmission lines, lumped parameter equivalent or distributed parameter simplification models are used to integrate the line's resistance, inductance, and capacitance parameters into appropriate equivalent parameters for calculation.

[0030] The simplified parameters are integrated and verified, and the equivalent parameters of various components are associated according to the simplified equivalent circuit structure to form complete equivalent circuit parameter data, ensuring that the equivalent circuit is consistent with the original system in key electrical characteristics.

[0031] The equivalent circuit parameter data is processed using time-domain analysis techniques to obtain transient current data, including: processing the equivalent circuit parameter data using time-domain analysis techniques to obtain a mathematical model of transient current components; and performing current superposition processing on the mathematical model of transient current components to obtain the transient current data.

[0032] Specifically, the circuit topology and characteristics of each component are determined based on the equivalent circuit parameters, and the triggering conditions for transient processes are determined, such as the occurrence of a fault or a sudden change in the system's operating state.

[0033] Based on Kirchhoff's laws and the current-voltage characteristics of components, a dynamic circuit equation for the equivalent circuit in the time domain is established. This equation reflects the relationship between voltage and current in the circuit and time.

[0034] Based on the physical characteristics of the transient process, the transient current is decomposed into different components, including the free component reflecting the sudden change in the initial state of the system, the forced component generated by external power supply excitation, and the additional component generated by component coupling or nonlinear characteristics.

[0035] For each decomposed current component, a mathematical model is established based on its corresponding physical mechanism and circuit equation. The model needs to reflect the law of change of each component over time, such as decay characteristics and rate of change. The mathematical expressions of all components are integrated to form a complete mathematical model of transient current components. Each component model has a clear physical meaning and calculation logic.

[0036] It should be noted that, in this process, a unified time dimension benchmark must be established, the time range and calculation step size of the transient process must be clearly defined, and all component models must be superimposed under the same time coordinate.

[0037] For each time node, based on the mathematical model of each component, the specific values ​​of each current component under that node are calculated. According to the direction characteristics of the current and the circuit connection relationship, the values ​​of each component at the same time node are algebraically superimposed. If the component currents are in the same direction, they are added together; if they are in opposite directions, they are subtracted together, thus obtaining the instantaneous value of the transient current at that time node.

[0038] According to the set time step, the instantaneous current value at each time node in the entire transient process is calculated sequentially. All instantaneous values ​​are arranged in chronological order to form complete transient current data. This data can intuitively present the waveform of the entire transient current from its occurrence to its decay or stabilization.

[0039] The steady-state parameter data and the transient current data are input into the constructed current processing model for processing to obtain the transient peak current of the bridge arm reactor. This includes: performing correlation and filtering processing on the steady-state parameter data and the transient current data to obtain the bridge arm current time domain sequence; and inputting the bridge arm current time domain sequence into the current processing model constructed based on the circuit transient response principle for processing to obtain the transient peak current.

[0040] Clearly define the basis for association, using parameters related to the bridge arm reactor in the steady-state parameter data as anchor points, such as the circuit node information corresponding to the rated inductance value of the bridge arm reactor and the reference current value of the bridge arm during steady-state operation of the system.

[0041] Based on correlation criteria, the transient current components flowing through the target bridge arm reactor are screened from the transient current data, while transient current data of other bridge arm lines or equipment are eliminated.

[0042] Meanwhile, the validity of the selected transient current data is verified by combining the bridge arm operation reference information in the steady-state parameters to ensure that the selected current data matches the electrical characteristics of the bridge arm reactor under steady-state conditions. The verified transient current data are arranged in chronological order to form a continuous bridge arm current time-domain sequence, which fully presents the trajectory of the current change of the bridge arm reactor over time during the transient process.

[0043] The time-domain sequence of the bridge arm current is standardized to ensure that the time step data format of the bridge arm current time-domain sequence is consistent with the input requirements preset by the model. If there are differences, the standardization adjustment is performed.

[0044] The adjusted bridge arm current time-domain sequence is input into the model. Based on the principle of circuit transient response, the model performs dynamic characteristic analysis on the current value at each time node in the sequence, including the current rise rate decay trend and abrupt change characteristics. These analyses are consistent with the change law of inductor current during the transient process. In the process of traversing the complete time-domain sequence, the model compares the instantaneous current value at each time node in real time and captures the maximum value, that is, the transient peak current of the bridge arm reactor.

[0045] Specifically, before blocking, the transient process exhibits strong nonlinearity due to the switching of submodules and is subject to control system regulation. Solving the entire transient process analytically is extremely complex and offers limited guidance for engineering design. Therefore, the circuit mathematical model can ignore the real-time changes in the switching states of the upper and lower bridge arm submodules during the transient process and can be considered a second-order linear circuit. To intuitively analyze the effect of current changes, a time-domain model is used.

[0046] The fault condition parameter data of the bridge arm reactor is simulated to obtain the simulated current, including: simulating the fault condition parameter data of the bridge arm reactor to obtain simulated current waveform data; and processing the simulated current waveform data using multi-fault point traversal sampling extraction technology to obtain the simulated current.

[0047] In this process, a simulation model of a pure half-bridge MMC flexible DC system was built based on PSCAD / EMTDC. The system parameters were input and randomly generated fault points were not the most severe operating conditions. Considering that the attenuation coefficient and initial phase are different, there will be appropriate deviations between the simulation results and the calculation results. Therefore, 20 fault points were set for one cycle to ensure that all severe operating conditions were traversed. The difference between the simulation results and the calculation results within 5% is within a reasonable range.

[0048] If the main wiring topology changes, the division of the aforementioned fault areas and the corresponding calculation process need to be adaptively optimized based on the topology adjustment.

[0049] Specifically, based on the topology and component parameters of the target flexible DC transmission system, a simulation model consistent with the actual system is built in a professional power system simulation platform. The model must accurately include core components such as bridge arm reactors, converters, and transmission lines.

[0050] Then, the fault condition parameters are organized according to the input requirements of the simulation platform, including fault type, fault location, fault timing, fault boundary conditions, etc., and then entered into the corresponding parameter modules of the simulation model in sequence.

[0051] Specifically, set the relevant simulation parameters, determine the simulation time range to ensure coverage of the entire process of fault occurrence, development and stabilization, set an appropriate time step to ensure the accuracy of the current waveform, start the simulation program, and the model will simulate the generation and change of current during the fault process according to the input fault condition parameters. After the simulation is completed, export the complete current-time curve data, i.e., the simulated current waveform data.

[0052] Based on the fault characteristics of the bridge arm reactor and actual operating experience, determine the range of fault points that need to be traversed, including different fault locations such as the front and rear ends of the bridge arm reactor, and different fault severity such as the fault level corresponding to different short-circuit resistances.

[0053] For each identified fault point, retrieve the corresponding simulated current waveform data, and select key sampling moments on the waveform according to the preset sampling rules, including characteristic moments such as the current rise phase, peak moment, and current decay phase at the moment the fault occurs.

[0054] The current value at each sampling moment is extracted, and the current data at different characteristic moments under each fault point is recorded, including key information such as the rate of change of the instantaneous value of the current peak. The sampling data of all fault points are integrated and filtered, and abnormal data is removed to form a simulation current that can comprehensively reflect the current characteristics of the bridge arm reactor under fault conditions. This data contains key current information under different fault scenarios and can be used to complement and verify the transient peak current.

[0055] Then, based on the obtained transient peak current and the simulated current, the peak current of the bridge arm reactor is obtained.

[0056] It should be noted that the precise value of the transient peak current and the corresponding transient process characteristics are extracted. This value is a theoretical limit value derived from the system equivalent circuit and time domain analysis, reflecting the current peak value under a specific transient scenario.

[0057] Specifically, the peak data of simulated current under different fault scenarios are analyzed to determine the impact of each fault scenario on the current peak value, and the maximum current peak value and corresponding fault type in the simulation data are identified. Then, by combining the characteristics of the two types of data, the correlation between the theoretical peak value and the simulated peak value is analyzed to determine whether the theoretical peak value can cover the extreme scenarios in the simulation, or whether the simulated peak value is closer to the actual extreme state due to the scenario setting.

[0058] By comparing the theoretical transient peak value and the simulated limiting peak value after fusion analysis, if the simulated limiting peak value is greater than the theoretical transient peak value, it indicates that the simulation scenario is closer to the actual extreme situation. The final peak current is determined based on the simulated limiting peak value and a preset safety margin. If the theoretical transient peak value is larger and verified to be reasonable, the final value is determined based on the theoretical transient peak value and a safety margin. Finally, the final peak current of the bridge arm reactor is output. This value includes both the accuracy of theoretical calculations and the comprehensiveness of actual fault scenarios, and can be directly used for system design and protection configuration.

[0059] In a specific embodiment, a ±260kV back-to-back pure half-bridge high-voltage flexible DC transmission project is taken as an example.

[0060] Fault identification and parameter acquisition: The DC voltage of both the positive and negative terminals was detected to drop sharply from 500kV to 0kV, and the positive current was detected to rise sharply from 3kA to 4.7kA, which was determined to be a grounding fault between the positive and negative terminals. Constructing an equivalent model and calculations: The main circuit is: positive submodule capacitor → positive converter valve → DC line → grounding fault point → negative line → negative submodule → positive module capacitor; A PSCAD simulation model was built, and simulation verification was carried out for this working condition. 20 points were scanned in a 20ms cycle to obtain the maximum value of the steady-state operating current of the bridge arm before the fault and the maximum value of the freewheeling current flowing through the diode after the fault. The peak current of the bridge arm reactor is obtained based on the maximum value of the steady-state operating current of the bridge arm before the fault and the magnitude of the freewheeling current flowing through the diode after the fault (transient peak current).

[0061] Another embodiment of the present invention provides a bridge arm reactor current calculation system based on a flexible DC transmission system. For details, please refer to [link to relevant documentation]. Figure 2 , Figure 2 The diagram shown is a structural schematic of a bridge arm reactor current calculation system based on a flexible DC transmission system according to one embodiment of the present invention. The system includes: The acquisition module 11 is used to acquire steady-state parameter data and topology parameter data of the target flexible DC transmission system; and to acquire fault condition parameter data of the bridge arm reactors in the target flexible DC transmission system. Extraction module 12 is used to extract and process the topology parameter data to obtain the equivalent circuit parameter data of the target flexible DC transmission system; Analysis module 13 is used to process the equivalent circuit parameter data using time-domain analysis technology to obtain transient current data; Processing module 14 is used to input the steady-state parameter data and the transient current data into the constructed current processing model for processing, so as to obtain the transient peak current of the bridge arm reactor; Simulation module 15 is used to simulate the fault condition parameter data of the bridge arm reactor to obtain the simulated current; The generation module 16 is used to obtain the peak current of the bridge arm reactor based on the transient peak current and the simulated current.

[0062] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for calculating the current of a bridge arm reactor in a flexible DC transmission system, characterized in that, include: Acquire steady-state parameter data and topology parameter data of the target flexible DC transmission system; Obtain fault condition parameter data of the bridge arm reactor in the target flexible DC transmission system; The equivalent circuit parameter data of the target flexible DC transmission system is obtained by extracting and processing the topology parameter data. The equivalent circuit parameter data is processed using time-domain analysis techniques to obtain transient current data; The steady-state parameter data and the transient current data are input into the constructed current processing model for processing to obtain the transient peak current of the bridge arm reactor. The fault condition parameter data of the bridge arm reactor are simulated to obtain the simulated current; The peak current of the bridge arm reactor is obtained based on the transient peak current and the simulated current.

2. The method for calculating the current of the bridge arm reactor based on a flexible DC transmission system as described in claim 1, characterized in that, The step of extracting and processing the topology parameter data to obtain the equivalent circuit parameter data of the target flexible DC transmission system includes: The topology parameter data is extracted and processed to obtain the basic circuit element parameters of the target flexible DC transmission system; The parameters of the basic circuit elements are processed using equivalent circuit simplification techniques to obtain the equivalent circuit parameter data of the target flexible DC transmission system.

3. The method for calculating the current of the bridge arm reactor based on a flexible DC transmission system as described in claim 1, characterized in that, The process of using time-domain analysis techniques to process the equivalent circuit parameter data to obtain transient current data includes: The equivalent circuit parameter data are processed using time-domain analysis techniques to obtain a mathematical model of the transient current components; The transient current component mathematical model is subjected to current superposition processing to obtain the transient current data.

4. The method for calculating the current of the bridge arm reactor based on a flexible DC transmission system as described in claim 1, characterized in that, The step of inputting the steady-state parameter data and the transient current data into the constructed current processing model for processing to obtain the transient peak current of the bridge arm reactor includes: The steady-state parameter data and the transient current data are correlated and filtered to obtain the time-domain sequence of the bridge arm current; The time-domain sequence of the bridge arm current is input into the current processing model constructed based on the principle of circuit transient response for processing to obtain the transient peak current.

5. The method for calculating the current of the bridge arm reactor based on a flexible DC transmission system as described in claim 1, characterized in that, The simulation processing of the fault condition parameter data of the bridge arm reactor to obtain the simulated current includes: The fault condition parameter data of the bridge arm reactor are simulated to obtain simulated current waveform data; The simulated current waveform data is processed using a multi-fault-point traversal sampling and extraction technique to obtain the simulated current.

6. A bridge arm reactor current calculation system based on a flexible DC transmission system, characterized in that, include: The acquisition module is used to acquire steady-state parameter data and topology parameter data of the target flexible DC transmission system; Obtain fault condition parameter data of the bridge arm reactor in the target flexible DC transmission system; The extraction module is used to extract and process the topology parameter data to obtain the equivalent circuit parameter data of the target flexible DC transmission system; The analysis module is used to process the equivalent circuit parameter data using time-domain analysis techniques to obtain transient current data; The processing module is used to input the steady-state parameter data and the transient current data into the constructed current processing model for processing, so as to obtain the transient peak current of the bridge arm reactor. The simulation module is used to simulate the fault condition parameter data of the bridge arm reactor to obtain the simulated current. The generation module is used to obtain the peak current of the bridge arm reactor based on the transient peak current and the simulated current.

7. The bridge arm reactor current calculation system based on a flexible DC transmission system as described in claim 6, characterized in that, The step of extracting and processing the topology parameter data to obtain the equivalent circuit parameter data of the target flexible DC transmission system includes: The topology parameter data is extracted and processed to obtain the basic circuit element parameters of the target flexible DC transmission system; The parameters of the basic circuit elements are processed using equivalent circuit simplification techniques to obtain the equivalent circuit parameter data of the target flexible DC transmission system.

8. The bridge arm reactor current calculation system based on a flexible DC transmission system as described in claim 6, characterized in that, The process of using time-domain analysis techniques to process the equivalent circuit parameter data to obtain transient current data includes: The equivalent circuit parameter data are processed using time-domain analysis techniques to obtain a mathematical model of the transient current components; The transient current component mathematical model is subjected to current superposition processing to obtain the transient current data.

9. The bridge arm reactor current calculation system based on a flexible DC transmission system as described in claim 6, characterized in that, The step of inputting the steady-state parameter data and the transient current data into the constructed current processing model for processing to obtain the transient peak current of the bridge arm reactor includes: The steady-state parameter data and the transient current data are correlated and filtered to obtain the time-domain sequence of the bridge arm current; The time-domain sequence of the bridge arm current is input into the current processing model constructed based on the principle of circuit transient response for processing to obtain the transient peak current.

10. The bridge arm reactor current calculation system based on a flexible DC transmission system as described in claim 6, characterized in that, The simulation processing of the fault condition parameter data of the bridge arm reactor to obtain the simulated current includes: The fault condition parameter data of the bridge arm reactor are simulated to obtain simulated current waveform data; The simulated current waveform data is processed using a multi-fault-point traversal sampling and extraction technique to obtain the simulated current.

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