Direct current filter design method and system of hybrid direct current system

Abstract

The invention discloses a direct current filter design method and system for a hybrid direct current system, and the method comprises the steps: generating a plurality of circuit simulation conditions according to the simulation input parameters of a direct current system and an alternating current system; the simulation working conditions of all the circuits are sequentially input into a pre-constructed hybrid direct-current power transmission system model, resonance characteristic scanning is conducted on the hybrid direct-current power transmission system model, and the hybrid direct-current power transmission system model is optimized and adjusted according to a scanning result; extracting a direct-current loop from the optimized hybrid direct-current power transmission system model to obtain a direct-current loop harmonic model; calculating the harmonic frequency spectrum of each node on the DC side based on the DC loop harmonic model, and obtaining the design parameters of the DC filter according to each harmonic frequency spectrum. By designing the parameters of the direct-current filter, the direct-current side harmonic waves are effectively suppressed, so that the harmonic voltage borne by a direct-current line under various operation conditions is greatly reduced, the requirement for the insulation level of the direct-current line can be reduced, and the construction cost of the whole direct-current power transmission system is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit design, and in particular, to a method and system for designing a DC filter for a hybrid DC system. Background Art

[0002] With the development of power systems and the increasing demand for long-distance and large-capacity power transmission, power transmission technologies are undergoing important changes. As a technology that can improve the efficiency of power transmission, DC transmission is of great significance for meeting the needs of modern power systems.

[0003] In existing DC transmission technologies, as an emerging power transmission method, the hybrid DC transmission system combines the advantages of traditional line commutated converters and modular multilevel converters, and has gradually become a research and application hotspot. However, existing hybrid DC systems often use default DC filters without reasonably configuring the parameters of the DC filters, resulting in problems of insufficient harmonic suppression and system stability in the actual operation of the hybrid DC system, and there is a resonance risk, which may cause abnormal amplification of harmonic voltages and currents, further exacerbate the insulation aging of equipment, and even may cause equipment failures.

[0004] Therefore, how to reasonably configure the DC filter to effectively suppress resonance has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0005] The present invention provides a method and system for designing a DC filter for a hybrid DC system to effectively suppress the harmonics of the hybrid DC transmission system.

[0006] To solve the above technical problems, an embodiment of the present invention provides a method for designing a DC filter for a hybrid DC system, including: Generating a plurality of circuit simulation conditions according to the simulation input parameters of the DC system and the AC system.

[0007] Sequentially inputting each of the circuit simulation conditions into a pre-constructed hybrid DC transmission system model, performing a resonance characteristic scan on the hybrid DC transmission system model, and optimizing and adjusting the hybrid DC transmission system model according to the scan results.

[0008] Extracting a DC loop from the optimized hybrid DC transmission system model to obtain a DC loop harmonic model.

[0009] Calculating the harmonic spectra of each node on the DC side based on the DC loop harmonic model, and obtaining the design parameters of the DC filter according to each of the harmonic spectra.

[0010] Further, generating a plurality of circuit simulation conditions according to the simulation input parameters of the DC system and the AC system, including: Collecting the simulation input parameters of the DC system and the AC system in the hybrid DC system, where the simulation input parameters include the rated voltage, rated current, and maximum transmission power of the DC line, as well as the rated voltage, short-circuit capacity, and background harmonic content of the AC bus.

[0011] Using the Monte Carlo method to simulate the operating state of the hybrid DC system based on each of the simulation input parameters, and generating a plurality of circuit simulation conditions.

[0012] Further, sequentially inputting each of the circuit simulation conditions into a pre-constructed hybrid DC transmission system model, performing a resonance characteristic scan on the hybrid DC transmission system model, and optimizing and adjusting the hybrid DC transmission system model according to the scan results, including: Constructing an electromagnetic transient simulation model of the hybrid DC system on simulation software as the hybrid DC transmission system model.

[0013] Sequentially inputting each of the circuit simulation conditions into the hybrid DC transmission system model, performing a resonance characteristic scan on the hybrid DC transmission system model, and obtaining the resonance frequency range on the DC side.

[0014] Judging whether the hybrid DC transmission system model needs to be configured with a line trap according to the resonance frequency range. If so, configuring the line trap of the hybrid DC transmission system model.

[0015] Further, judging whether the hybrid DC transmission system model needs to be configured with a line trap according to the resonance frequency range, including: If the resonance frequency range is within a preset frequency band interval, it is judged that the hybrid DC transmission system model needs to be configured with a line trap, where the frequency band interval includes the power frequency and multiples of the power frequency.

[0016] Further, extracting the DC loop from the optimized hybrid DC transmission system model to obtain a DC loop harmonic model, including: Extracting the DC loop structure and structure parameters from the optimized hybrid DC transmission system model, where the DC loop structure includes a DC line, a smoothing reactor, and a DC filter.

[0017] Constructing a DC loop harmonic model according to the extracted DC loop structure and the structure parameters.

[0018] Further, calculating the harmonic spectra of each node on the DC side based on the DC loop harmonic model, and obtaining the design parameters of the DC filter according to each of the harmonic spectra, including: Input each of the circuit simulation conditions into the DC loop harmonic model, and calculate the first harmonic spectrum and the second harmonic spectrum of each node on the DC side of the DC filter in the enabled and disabled states respectively under different conditions.

[0019] Obtain the design parameters of the DC filter according to the first harmonic spectrum and the second harmonic spectrum.

[0020] Furthermore, the method further includes: Configure the DC filter according to the design parameters, and load the configured DC filter into the target hybrid DC system.

[0021] Evaluate the dynamic response and stability of the target hybrid DC system under different loads and different fault conditions, and generate a visual evaluation report of the hybrid DC system.

[0022] Design and install the DC filter according to the visual evaluation report.

[0023] Another embodiment of the present invention provides a DC filter design system for a hybrid DC system, including: A condition generation module, configured to generate a plurality of circuit simulation conditions according to the simulation input parameters of the DC system and the AC system.

[0024] A model optimization module, configured to input each of the circuit simulation conditions into a pre-constructed hybrid DC power transmission system model in sequence, perform a resonance characteristic scan on the hybrid DC power transmission system model, and optimize and adjust the hybrid DC power transmission system model according to the scan results.

[0025] A loop extraction module, configured to extract the DC loop from the optimized hybrid DC power transmission system model to obtain a DC loop harmonic model.

[0026] A parameter design module, configured to calculate the harmonic spectrum of each node on the DC side based on the DC loop harmonic model, and obtain the design parameters of the DC filter according to each harmonic spectrum.

[0027] Furthermore, the model optimization module is configured to: Construct an electromagnetic transient simulation model of the hybrid DC system on the simulation software as the hybrid DC power transmission system model.

[0028] Input each of the circuit simulation conditions into the hybrid DC power transmission system model in sequence, perform a resonance characteristic scan on the hybrid DC power transmission system model, and obtain the resonance frequency range on the DC side.

[0029] Determine whether a line trap needs to be configured for the hybrid HVDC system model according to the resonant frequency range. If so, configure the line trap for the hybrid HVDC system model.

[0030] Further, the parameter design module is used for: Input each of the circuit simulation conditions into the DC loop harmonic model, and calculate the first harmonic spectrum and the second harmonic spectrum of each node on the DC side in the enabled and disabled states of the DC filter under different conditions respectively.

[0031] Obtain the design parameters of the DC filter according to the first harmonic spectrum and the second harmonic spectrum.

[0032] Compared with the prior art, the beneficial effects of the embodiments of the present invention are at least one of the following: By designing the parameters of the DC filter, the harmonics on the DC side are effectively suppressed, the harmonic voltages borne by the DC line under various operating conditions are greatly reduced, so that the insulation level requirements can be reduced, and the construction cost of the entire HVDC system can be reduced.

[0033] By simulating a variety of conditions to optimize the model, it can be ensured that the harmonic spectra of each node and component on the DC side of the circuit system meet the standard requirements under different operating conditions, avoiding the interference and impact of harmonics on the system operation, reducing problems such as equipment failures and system oscillations caused by harmonics, and improving the safe and stable operation ability of the HVDC system. Description of the Drawings

[0034] Figure 1 It is a step flow chart of the DC filter design method for the hybrid DC system provided by the embodiment of the present invention; Figure 2 It is a structural block diagram of the DC filter design system for the hybrid DC system provided by the embodiment of the present invention. Detailed Embodiments

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the 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 making creative efforts shall fall within the protection scope of the present invention.

[0036] In the description of this application, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", "third", etc. may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0037] In the description of this application, it should be noted that, unless otherwise clearly specified and defined, the terms "installed", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. The terms "vertical", "horizontal", "left", "right", "upper", "lower" and similar expressions used herein are for illustrative purposes only and do not indicate or imply that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0038] In the description of this application, 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 those of ordinary skill in the technical field to which this invention belongs. The terms used in the specification of this invention are only for the purpose of describing specific embodiments and are not intended to limit this invention. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] An embodiment of the present invention provides a method for designing a DC filter of a hybrid DC system. Specifically, please refer to Figure 1 , Figure 1 which shows a flowchart of the steps of the method for designing a DC filter of a hybrid DC system in one embodiment of the present invention, including steps S11 to S14: Step S11: Generate a number of circuit simulation conditions according to the simulation input parameters of the DC system and the AC system.

[0040] The hybrid DC system consists of a DC part and an AC part, each with its unique operating characteristics and parameters. To accurately conduct circuit simulation, these parameters must be comprehensively collected; otherwise, the actual operating conditions of the system cannot be fully reflected. Collect the simulation input parameters of the DC system and the AC system in the hybrid DC system. Among them, the simulation input parameters include the rated voltage, rated current, maximum and minimum transmission powers, and various operating modes of the DC line in the DC system, as well as the rated voltage, short-circuit capacity, background harmonic content, maximum and minimum values of short-circuit impedance of the AC bus in the AC system, etc. Collect the key parameters in multiple above-mentioned hybrid DC systems. By collecting these parameters, the boundary conditions in the simulation process, such as the rated voltage and rated current of the DC line, can be determined, providing clear constraint conditions for the simulation calculation.

[0041] The operating state of the power system is affected by various factors and has a certain degree of uncertainty. As a stochastic simulation method, the Monte Carlo method can consider these uncertainty factors and simulate different operating states of the system through multiple random samplings.

[0042] Use the Monte Carlo method to simulate the operating state of the hybrid DC system based on each simulation input parameter, and generate several circuit simulation conditions.

[0043] The Monte Carlo method generates multiple simulation conditions through random sampling and can simulate the behavior of the hybrid DC system under various possible operating states. Specifically, the circuit simulation conditions generated in this embodiment include three types: normal operation, fault operation, and transition operation, and each type contains multiple specific conditions.

[0044] By generating multiple simulation conditions, different simulation scenarios can be provided for the subsequent harmonic scanning of the hybrid DC system under different operating conditions.

[0045] Step S12: Sequentially input each circuit simulation condition into the pre-constructed hybrid DC transmission system model, conduct a resonance characteristic scan on the hybrid DC transmission system model, and optimize and adjust the hybrid DC transmission system model according to the scan results.

[0046] The hybrid DC system contains complex electromagnetic transient processes, which play a key role in system design, operation, and optimization. The electromagnetic transient simulation model can accurately simulate these dynamic behaviors and provide a basis for system analysis and research. In this embodiment, an electromagnetic transient simulation model of the hybrid DC system is constructed on the PSCAD / EMTDC simulation software as the hybrid DC transmission system model.

[0047] By constructing this hybrid DC transmission system model, it can be verified in a virtual environment whether the design of the hybrid DC transmission system is reasonable and whether it meets the expected performance requirements, thus avoiding risks and costs in actual construction.

[0048] Each circuit simulation condition is successively input into the hybrid HVDC system model, and then the resonance characteristics of the hybrid HVDC system model are scanned to obtain the resonance frequency range on the DC side.

[0049] Specifically, in this embodiment, the resonance characteristics of the hybrid HVDC system model are scanned respectively according to the three types of circuit simulation conditions of normal operation, fault operation, and transition operation obtained in step S11, and the first resonance frequency range corresponding to the normal operation condition, the second resonance frequency range corresponding to the fault operation condition, and the third resonance frequency range corresponding to the transition operation condition are obtained respectively, and the line traps of the hybrid HVDC system are set according to these three different resonance frequency ranges respectively.

[0050] Under the normal operation condition, the obtained first resonance frequency range reflects the resonance frequencies that may occur when the system is operating normally. If the first resonance frequency range is close to the normal operating frequency of the system or the natural frequency of the equipment, it may cause system oscillation and affect the normal operation of the equipment.

[0051] The second resonance frequency range obtained under the fault operation condition reflects the resonance frequencies that may occur when the system is in a fault condition. The resonance frequencies under the fault operation condition may be different from those under the normal operation condition and may pose a greater threat to the stability of the system. Therefore, separate scanning is required.

[0052] The third resonance frequency range obtained under the transition operation condition reflects the resonance frequencies that may occur when the system is in transition operation. The resonance frequencies under the transition operation condition may vary between the normal and fault operation conditions.

[0053] The resonance characteristics of the hybrid HVDC system may be different under different operation conditions (normal operation, fault operation, and transition operation). By scanning the resonance characteristics of these conditions respectively, the resonance behavior of the system in various situations can be comprehensively evaluated to ensure that the system can remain stable in all possible operating states.

[0054] Scanning the resonance characteristics under different operation conditions can help identify potential risks in the system in various situations, especially the resonance frequencies under fault and transition operation conditions, which may pose a greater threat to the stability of the system and the safe operation of the equipment.

[0055] It is determined respectively according to the first resonance frequency range, the second resonance frequency range, and the third resonance frequency range whether the hybrid HVDC system model needs to be configured with line traps in the normal, fault, and transition operating states. If so, line traps are selected for the hybrid HVDC system model in different operating states according to the specific resonance frequency range and the parameters of the line traps are configured according to the corresponding resonance frequency range.

[0056] Specifically, the method for determining whether to set a line trap in this embodiment is as follows: If the resonance frequency range is within a preset frequency band interval, it is determined that the hybrid HVDC system model needs to be configured with a line trap. Among them, the frequency band interval corresponding to the first resonance frequency range includes the vicinity of the power frequency and the vicinity of the multiple frequencies of the power frequency. The fluctuation range between it and the power frequency can be 5 - 10 Hz, which is specifically determined according to the actual operating state. The selected fluctuation range in this embodiment is ±5 Hz, and the power frequency uses the internationally common 50 Hz. Therefore, the frequency band interval corresponding to the first resonance frequency range selected in this embodiment is within the range of 45 - 55 Hz and its multiple frequency intervals.

[0057] Since the second resonance frequency range and the third resonance frequency range respectively correspond to faults and transition conditions, the corresponding frequency intervals can be measured during the operation of the hybrid DC system, and they are both within a specified frequency and its multiple frequency intervals.

[0058] Step S13: Extract the DC loop from the optimized hybrid HVDC system model to obtain the DC loop harmonic model.

[0059] The DC loop in the hybrid HVDC system is an important part of the system, and its characteristics directly affect the harmonic performance of the system. By extracting the DC loop structure and structure parameters, it is possible to focus on analyzing and optimizing the harmonic characteristics of the DC loop.

[0060] The extracted DC loop structure and structure parameters are the basis for constructing the DC loop harmonic model. According to the mentioned DC loop structure and corresponding structure parameters, a DC loop harmonic model including at least the parameters of the DC line, the smoothing reactor, and the DC filter is constructed to obtain the DC loop harmonic model.

[0061] The hybrid DC system includes various components in the entire circuit system, including DC lines, converters, AC buses, energy storage devices, and other structures and components. By first constructing a complete hybrid DC system model and performing the optimization process based on the complete system model, it can more accurately reflect the actual operating state of the system. The optimized model not only considers the characteristics of the DC loop but also the influence of other parts on the DC loop, making the finally extracted DC loop structure and parameters more accurate, and the constructed DC loop harmonic model closer to its actual operating state in the complete circuit system.

[0062] This optimization method not only considers the performance of the DC loop but also the stability and reliability of the hybrid DC system under different operating conditions, reducing errors and inaccurate factors in the model.

[0063] Step S14: Calculate the harmonic spectra of each node on the DC side based on the DC loop harmonic model, and obtain the design parameters of the DC filter according to each harmonic spectrum.

[0064] Input the circuit simulation conditions into the DC loop harmonic model, and calculate the harmonic spectrum of the DC filter under different conditions respectively.

[0065] Specifically, the calculation process is as follows: First, deactivate the DC filter. In the state where the DC filter is not enabled, input the parameters of each circuit simulation condition into the DC loop harmonic model to obtain the second harmonic spectrum of each node on the DC side.

[0066] Obtain the harmonic information to be suppressed based on the second harmonic spectrum, and perform preliminary settings on the filter according to this information.

[0067] Enable the DC filter with the preliminary set parameters, and scan the DC loop harmonic model under each circuit simulation condition again to obtain the first harmonic spectrum.

[0068] If the first harmonic spectrum falls within the range of reasonable normal resonance phenomena, determine the parameters of the DC filter according to the first harmonic spectrum; otherwise, adjust the parameters of the DC loop harmonic model, deactivate the DC filter again, obtain a new second harmonic spectrum, and correct the first harmonic spectrum with the new second harmonic spectrum until the first harmonic spectrum enters the spectrum range corresponding to the reasonable normal resonance phenomenon when the DC filter is in the enabled state.

[0069] Preferably, this embodiment further includes step S15, configuring the DC filter according to the design parameters, loading the configured DC filter into the target hybrid DC system, integrating the DC filter into the actual operating system, and ensuring that the harmonic performance of the system meets the design requirements during actual operation.

[0070] The dynamic response and stability of the hybrid DC system under different loads and different fault conditions are key indicators in system design and operation. By evaluating these performance indicators, the operating characteristics of the system can be comprehensively understood. Therefore, this embodiment evaluates the dynamic response and stability of the target hybrid DC system under different loads and different fault conditions, generates a visual evaluation report of the hybrid DC system, which can intuitively display the performance indicators of the system, facilitating designers and managers to understand the operating state of the hybrid DC system.

[0071] Design and install the DC filter according to the visual evaluation report.

[0072] The DC filter design method for the hybrid DC system of the present invention effectively suppresses the harmonics on the DC side by designing the DC filter parameters, significantly reducing the harmonic voltage borne by the DC line under various operating conditions. As a result, the requirement for its insulation level can be reduced, and the construction cost of the entire DC transmission system can be lowered. By simulating various operating conditions to optimize the model, it can ensure that the harmonic spectra of each node and component on the DC side of the circuit system meet the standard requirements under different operating conditions, avoiding interference and impact of harmonics on the system operation, reducing problems such as equipment failures and system oscillations caused by harmonics, and improving the safe and stable operation ability of the DC transmission system.

[0073] An embodiment of the present invention also provides a DC filter design system for a hybrid DC system, which is used to execute the DC filter design method for the hybrid DC system as described above. Figure 2 The following is the structural block diagram of the DC filter design system for the hybrid DC system of the embodiment of the present invention. The system includes: A working condition generation module 21, which is used to generate a number of circuit simulation working conditions according to the simulation input parameters of the DC system and the AC system.

[0074] A model optimization module 22, which is used to sequentially input each of the circuit simulation working conditions into a pre-constructed hybrid DC transmission system model, perform a resonance characteristic scan on the hybrid DC transmission system model, and optimize and adjust the hybrid DC transmission system model according to the scan results.

[0075] A loop extraction module 23, which is used to extract the DC loop from the optimized hybrid DC transmission system model to obtain a DC loop harmonic model.

[0076] A parameter design module 24, which is used to calculate the harmonic spectra of each node on the DC side based on the DC loop harmonic model, and obtain the design parameters of the DC filter according to each of the harmonic spectra.

[0077] Among them, the model optimization module is used for: Construct an electromagnetic transient simulation model of the hybrid DC system on the simulation software as the hybrid DC transmission system model; Sequentially input each of the circuit simulation working conditions into the hybrid DC transmission system model, perform a resonance characteristic scan on the hybrid DC transmission system model, and obtain the resonance frequency range on the DC side; Judge whether the hybrid DC transmission system model needs to be configured with a choke according to the resonance frequency range. If so, configure the choke of the hybrid DC transmission system model.

[0078] The parameter design module is used for: Input each of the circuit simulation conditions into the DC loop harmonic model, and calculate the first harmonic spectrum and the second harmonic spectrum of each node on the DC side of the DC filter in the enabled and disabled states respectively under different conditions; Obtain the design parameters of the DC filter according to the first harmonic spectrum and the second harmonic spectrum.

[0079] The technical features and technical effects of the system proposed in the embodiments of the present invention are the same as those of the method proposed in the embodiments of the present invention, and will not be elaborated here. Each module in the above device can be implemented in whole or in part by software, hardware and their combination. Each of the above modules can be embedded in or independent of the processor in the computer device in the form of hardware, or stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0080] The above embodiments only represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended claims.

Claims

1. A DC filter design method for a hybrid DC system, characterized in that: include: Generate several circuit simulation conditions according to the simulation input parameters of the DC system and the AC system; sequentially inputting each of the circuit simulation conditions into a pre-built hybrid DC power transmission system model, scanning the resonance characteristics of the hybrid DC power transmission system model, and optimizing and adjusting the hybrid DC power transmission system model according to the scanning results; Extracting a DC circuit from the optimized hybrid DC transmission system model to obtain a DC circuit harmonic model; The harmonic spectrum of each node on the DC side is calculated based on the DC circuit harmonic model, and the design parameters of the DC filter are obtained according to each harmonic spectrum.

2. The DC filter design method for a hybrid DC system according to claim 1, characterized in that: According to the simulation input parameters of the DC system and the AC system, a plurality of circuit simulation conditions are generated, including: Collecting simulation input parameters of a DC system and an AC system in a hybrid DC system, wherein the simulation input parameters include a rated voltage, a rated current, and a maximum transmission power of a DC line, and a rated voltage, a short-circuit capacity, and a background harmonic content of an AC bus; The operating state of the hybrid DC system is simulated based on the simulation input parameters using the Monte Carlo method to generate a plurality of circuit simulation conditions.

3. The DC filter design method of the hybrid DC system according to claim 1, characterized in that: The step of sequentially inputting each of the circuit simulation conditions into a pre-built hybrid DC power transmission system model, scanning the resonance characteristics of the hybrid DC power transmission system model, and optimizing and adjusting the hybrid DC power transmission system model according to the scanning results includes: An electromagnetic transient simulation model of a hybrid DC system is constructed on the simulation software as a hybrid DC transmission system model; Inputting each circuit simulation working condition into the hybrid DC power transmission system model in turn, scanning the resonance characteristics of the hybrid DC power transmission system model, and obtaining the resonance frequency range of the DC side; It is determined whether the hybrid DC power transmission system model needs to be configured with a surge arrester according to the resonant frequency range, and if so, the surge arrester of the hybrid DC power transmission system model is configured.

4. The DC filter design method for a hybrid DC system according to claim 3, characterized in that: The determining, according to the resonant frequency range, whether the hybrid direct current power transmission system model needs to be configured with a wave trap comprises: If the resonant frequency range is within a preset frequency band, it is determined that the hybrid direct current power transmission system model needs to be configured with a wave trap, wherein the frequency band includes the power frequency and a multiple of the power frequency.

5. The DC filter design method for a hybrid DC system according to claim 1, characterized in that: The step of extracting a DC circuit from the optimized hybrid DC power transmission system model to obtain a DC circuit harmonic model includes: Extracting a DC loop structure and structural parameters from the optimized hybrid DC power transmission system model, wherein the DC loop structure includes a DC line, a smoothing reactor and a DC filter; A DC link harmonic model is constructed according to the extracted DC link structure and the structural parameters.

6. The DC filter design method of the hybrid DC system according to claim 1, characterized in that: The calculating the harmonic spectrum of each node on the DC side based on the DC circuit harmonic model, and obtaining the design parameters of the DC filter according to each harmonic spectrum, includes: Inputting each of the circuit simulation working conditions into the DC circuit harmonic model, and respectively calculating the first harmonic spectrum and the second harmonic spectrum of each node on the DC side of the DC filter in an enabled and disabled state under different working conditions; The design parameters of the DC filter are obtained according to the first harmonic spectrum and the second harmonic spectrum.

7. The DC filter design method for a hybrid DC system according to claim 1, characterized in that: The method further comprises: Configuring the DC filter according to the design parameters, and loading the configured DC filter into a target hybrid DC system; Evaluate the dynamic response and stability of the target hybrid DC system under different loads and different fault conditions, and generate a visual evaluation report of the hybrid DC system; The DC filter is designed and installed according to the visual evaluation report.

8. A DC filter design system for a hybrid DC system, characterized in that: include: A working condition generation module is used to generate a number of circuit simulation working conditions according to simulation input parameters of a DC system and an AC system; A model optimization module, used for sequentially inputting each of the circuit simulation conditions into a pre-built hybrid DC power transmission system model, scanning the resonance characteristics of the hybrid DC power transmission system model, and optimizing and adjusting the hybrid DC power transmission system model according to the scanning results; A circuit extraction module is used to extract a DC circuit from the optimized hybrid DC power transmission system model to obtain a DC circuit harmonic model; The parameter design module is used to calculate the harmonic spectrum of each node on the DC side based on the DC circuit harmonic model, and obtain the design parameters of the DC filter according to each harmonic spectrum.

9. The DC filter design system for a hybrid DC system according to claim 8, characterized in that: The model optimization module is used to: An electromagnetic transient simulation model of a hybrid DC system is constructed on the simulation software as a hybrid DC transmission system model; Inputting each circuit simulation working condition into the hybrid DC power transmission system model in turn, scanning the resonance characteristics of the hybrid DC power transmission system model, and obtaining the resonance frequency range of the DC side; It is determined whether the hybrid DC power transmission system model needs to be configured with a surge arrester according to the resonant frequency range, and if so, the surge arrester of the hybrid DC power transmission system model is configured.

10. The DC filter design system for a hybrid DC system according to claim 8, characterized in that: The parameter design module is used for: Inputting each of the circuit simulation working conditions into the DC circuit harmonic model, and respectively calculating the first harmonic spectrum and the second harmonic spectrum of each node on the DC side of the DC filter in an enabled and disabled state under different working conditions; The design parameters of the DC filter are obtained according to the first harmonic spectrum and the second harmonic spectrum.

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