Method and system for determining steady-state parameters of SVG connection reactor of SLCC

Abstract

The invention discloses a method and a system for determining steady-state parameters of an SVG (Static Var Generator) connection reactor of an SLCC, which are applied to the field of direct-current transmission and comprise the following steps of: determining actual reactive power and intermediate parameters of the SVG based on an SLCC reactive power control target and initial parameters of the reactor; determining an SVG total output current and an SVG total output voltage for obtaining a current margin coefficient based on the SVG harmonic control target, the SVG actual reactive power and the intermediate parameters; determining a voltage simulation result of the SVG connected with the reactor based on the current margin coefficient; and after the SVG harmonic control target is adjusted based on the voltage simulation result, if the updated voltage simulation result does not meet the preset requirement, adjusting the initial parameters of the reactor and returning to execute the above steps. According to the method, the optimal reactor parameters are determined through closed loop of equipment parameter calculation, simulation verification, feedback and adjustment, and the stability of the SLCC system and the selection accuracy of the reactor parameters are improved while the requirements of the SLCC system are matched.

Description

Technical Field

[0001] This invention relates to the field of DC power transmission technology, and in particular to a method and system for determining the steady-state parameters of an SVG-connected reactor in a SLCC (Signal-Static Coupling). Background Technology

[0002] In SLCC (Series Line-Commutated Converter) DC transmission systems, the existing method for selecting parameters of the SVG (Static Var Generator) connected reactors is based on engineering experience and does not consider the topology characteristics and operating conditions of the SLCC DC transmission system. This leads to reactor parameters that are either too large or too small based on experience. Large reactor parameters result in a decrease in the reactive power regulation response speed of the SVG, making it unable to match the dynamic reactive power demand of the SLCC in a timely manner, and may even affect the system voltage stability. Small reactor parameters, on the other hand, are insufficient to effectively suppress transient currents, increase system harmonic losses, and may cause damage to the internal switching devices of the SVG due to excessive current stress. Summary of the Invention

[0003] This invention provides a method and system for determining the steady-state parameters of SVG-connected reactors in SLCCs, in order to solve the technical problem of inaccurate parameter selection in existing SVG-connected reactors for SLCCs.

[0004] To address the aforementioned technical problems, embodiments of the present invention provide a method for determining the steady-state parameters of an SVG-connected reactor in a SLCC, comprising: Based on the reactive power control target of the SLCC phase converter in the cascaded power grid and the initial parameters of the reactor, the actual reactive power and intermediate parameters of the static var generator (SVG) are determined. Based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters, the total output current and total output voltage of the SVG used to obtain the current margin coefficient are determined. The voltage simulation results of the SVG-connected reactor are determined based on the current margin coefficient. After adjusting the SVG harmonic control target based on the voltage simulation results, if the updated voltage simulation results do not meet the preset requirements, the initial parameters of the reactor are adjusted and the process of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor is returned.

[0005] As one preferred embodiment, determining the total SVG output current and total SVG output voltage for obtaining the current margin coefficient based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters includes: Determining SVG harmonic control targets based on SLCC topology; The fundamental current of the SVG is determined based on the actual reactive power of the SVG and the intermediate parameters. Based on the SVG harmonic control target and the SVG fundamental current, determine the SVG total output current and the SVG total output voltage; The current margin coefficient is determined based on the initial parameters of the reactor, the total output current of the SVG, and the total output voltage of the SVG.

[0006] As one preferred embodiment, the voltage simulation results for determining the SVG connected reactor based on the current margin coefficient include: If the current margin coefficient is not within the preset range, then adjust the initial parameters of the reactor and return to the steps of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor; If the current margin coefficient is within the preset range, then based on the SLCC reactive power control target, the initial parameters of the reactor, and the voltage of the SVG connected reactor, the voltage simulation results are obtained.

[0007] As one preferred embodiment, the step of determining the voltage simulation results of the SVG connected reactor based on the current margin coefficient includes: If the voltage simulation result shows that the simulation voltage meets the withstand requirements of the SVG-connected reactor, the initial parameters of the reactor are determined to be the steady-state parameters of the SVG-connected reactor. If the voltage simulation result shows that the simulated voltage does not meet the withstand requirements of the SVG connected reactor, the SVG harmonic control target is adjusted, and the steps for determining the SVG total output current and SVG total output voltage for obtaining the current margin coefficient are returned based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters.

[0008] As one preferred embodiment, the step of adjusting the SVG harmonic control target based on the voltage simulation results, and if the updated voltage simulation results do not meet the preset requirements, adjusting the initial parameters of the reactor and returning to determine the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor includes: After adjusting the SVG harmonic control target based on the voltage simulation results, if the updated simulation voltage meets the withstand requirement, then the initial parameters of the reactor are determined to be the steady-state parameters of the SVG connected reactor. After adjusting the SVG harmonic control target based on the voltage simulation results, if the updated simulation voltage does not meet the withstand requirement, the initial parameters of the reactor are adjusted and the process of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor is returned.

[0009] Another embodiment of the present invention provides a system for determining the steady-state parameters of an SVG-connected reactor in a SLCC, comprising: The SLCC system parameter determination module is used to determine the actual reactive power and intermediate parameters of the Static Var Generator (SVG) based on the reactive power control target of the SLCC phase-commutator in the cascaded power grid and the initial parameters of the reactor. The SVG total output determination module is used to determine the SVG total output current and SVG total output voltage for obtaining the current margin coefficient based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters. The voltage simulation module is used to determine the voltage simulation results of the SVG connected reactor based on the current margin coefficient. The reactor parameter adjustment module is used to adjust the initial parameters of the reactor and return the steps of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor after adjusting the SVG harmonic control target based on the voltage simulation results and if the updated voltage simulation results do not meet the preset requirements.

[0010] As one preferred embodiment, the SVG total output determination module includes: An SVG harmonic control target determination unit is used to determine the SVG harmonic control target based on the SLCC topology. The SVG fundamental current determination unit is used to determine the SVG fundamental current based on the actual reactive power of the SVG and the intermediate parameters. The SVG total output power determination unit is used to determine the SVG total output current and SVG total output voltage based on the SVG harmonic control target and the SVG fundamental current. The current margin coefficient determination unit is used to determine the current margin coefficient based on the initial parameters of the reactor, the total output current of the SVG, and the total output voltage of the SVG.

[0011] As one preferred embodiment, the voltage simulation module includes: The reactor initial parameter adjustment unit is used to adjust the reactor initial parameters and return the steps of determining the actual reactive power and intermediate parameters of SVG based on the SLCC reactive power control target and the reactor initial parameters if the current margin coefficient is not within the preset range. The voltage simulation unit is used to simulate the voltage of the SVG-connected reactor based on the SLCC reactive power control target, the initial parameters of the reactor, and if the current margin coefficient is within a preset range, and to obtain the voltage simulation results.

[0012] As one preferred embodiment, the SLCC SVG-connected reactor steady-state parameter determination system further includes: The steady-state parameter determination module is used to determine the initial parameters of the reactor as the steady-state parameters of the SVG-connected reactor when the voltage simulation result shows that the simulation voltage meets the withstand requirements of the SVG-connected reactor. The SVG harmonic control target adjustment module is used to adjust the SVG harmonic control target when the voltage simulation result shows that the simulated voltage does not meet the withstand requirements of the SVG connected reactor, and to return the steps of determining the SVG total output current and SVG total output voltage for obtaining the current margin coefficient based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters.

[0013] As one preferred embodiment, the reactor parameter adjustment module includes: The steady-state parameter determination unit is used to determine the initial parameters of the reactor as the steady-state parameters of the SVG connected reactor if the updated simulation voltage meets the tolerance requirement after adjusting the SVG harmonic control target based on the voltage simulation results. The reactor parameter adjustment unit is used to adjust the initial parameters of the reactor and return to the steps of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor after adjusting the SVG harmonic control target based on the voltage simulation results and if the updated simulation voltage does not meet the withstand requirements.

[0014] This invention provides a method and system for determining the steady-state parameters of an SVG-connected reactor in a Series-Based Cushioning (SLCC). By setting SLCC reactive power control targets, SVG harmonic control targets, and initial reactor parameters, the actual reactive power and intermediate parameters of the SVG are determined, transforming the SLCC system requirements into specific equipment parameters. These specific equipment parameters are then used to determine the total output current and voltage of the SVG for obtaining the current margin coefficient. Output calculations yield the current margin necessary to ensure safe system operation. Finally, simulation verification forms a feedback and adjustment closed loop, iteratively optimizing and determining the optimal reactor parameters. This invention, through equipment parameter calculation, simulation verification, and a feedback and adjustment closed loop to determine the optimal reactor parameters, improves SLCC system stability and the accuracy of reactor parameter selection while matching SLCC system requirements. Attached Figure Description

[0015] Figure 1This is one of the flowcharts illustrating the method for determining the steady-state parameters of the SVG-connected reactor in SLCC provided by the present invention; Figure 2 This is the second flowchart illustrating the method for determining the steady-state parameters of the SVG-connected reactor in SLCC provided by this invention. Figure 3 This is a schematic diagram of the SVG-connected reactor steady-state parameter determination system for SLCC provided by the present invention.

[0016] Figure label: Among them, 301 is the SLCC system parameter determination module; 302 is the SVG total output determination module; 303 is the voltage simulation module; and 304 is the reactor parameter adjustment module. Detailed Implementation

[0017] 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.

[0018] 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 number of indicated technical features. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0019] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between 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 device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0020] 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 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 application based on the specific circumstances.

[0021] See Figure 1 , Figure 1 This is a flowchart illustrating an embodiment of the method for determining the steady-state parameters of the SVG-connected reactor in SLCC provided by the present invention, as shown below. Figure 1 As shown, this embodiment includes steps 100 to 400, and the specific steps are as follows: Step 100: Based on the reactive power control target of the cascaded grid phase-commutator converter SLCC and the initial parameters of the reactor, determine the actual reactive power and intermediate parameters of the static var generator SVG; First, we define the reactive power target that the SLCC converter station needs to absorb or inject from the AC system (i.e., the SLCC reactive power control target in this embodiment), and the specific harmonics that the SVG needs to compensate for (i.e., the SVG harmonic control target described below, for example, 6k±1, 12k±1, or full-spectrum harmonics). The control target is used to determine the boundary conditions for subsequent calculations, where the selection of the harmonic control target affects the voltage stress on the reactor.

[0022] Based on the determination of the reactive power control target of SLCC (clarifying the reactive power range that SVG needs to compensate) and the harmonic control target of SVG (the harmonic frequency band that SVG needs to suppress), an initial reactor parameter (such as the initial inductance value) is selected to calculate the actual reactive power and intermediate parameters of SVG. The actual reactive power of SVG refers to the reactive power that SVG needs to provide in steady-state operation of SLCC system. The intermediate parameters used subsequently include equivalent impedance, commutation angle and valve side current, etc.

[0023] Step 200: Based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters, determine the total output current and total output voltage of the SVG used to obtain the current margin coefficient; Determine the fundamental current obtained when calculating the actual reactive power and intermediate parameters of the SVG in step 100 above. Based on the SVG harmonic control target, the actual reactive power of the SVG, and the equivalent impedance, and combined with the harmonic spectrum of the converter station, calculate the target harmonic current (e.g., 11th, 13th) and the natural shunt harmonics (e.g., 5th, 7th). The total output current of the SVG includes the mean square sum of the fundamental current and the harmonic currents; the total output voltage of the SVG is the superposition of the voltage required for target harmonic compensation, the voltage generated by the natural shunt harmonics, and the highest voltage on the valve side.

[0024] Step 300: Determine the voltage simulation results of the SVG connected reactor based on the current margin coefficient; Specifically, in this scheme, the first condition for iteratively adjusting the initial parameters of the reactor is the current margin coefficient, which is determined based on the total output current and total output voltage of the SVG. For example, if the current margin coefficient k is not within the range of 1.2-1.5, the reactor inductance value is immediately reselected. Then, the initial parameters of the reactor are iteratively adjusted until the current margin coefficient is updated due to the adjustment of the initial parameters of the reactor. In the current margin factor In this case, the voltage withstand capability is further verified by transient simulation to obtain voltage simulation results, which include both equipment-constrained and equipment-unconstrained scenarios.

[0025] Step 400: After adjusting the SVG harmonic control target based on the voltage simulation results, if the updated voltage simulation results do not meet the preset requirements, adjust the initial parameters of the reactor and return to the step of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor.

[0026] Specifically, given the voltage simulation results indicating an adjustment to the SVG harmonic control target, the maximum voltage of the connected reactor under the control target is simulated. The voltage withstand capability is verified through transient simulation. If the updated voltage simulation result shows that the simulated voltage does not meet the withstand requirements of the SVG connected reactor, indicating equipment limitations, the control target of the SLCC and the initial parameters of the reactor are further adjusted. The simulation is then iterated again in step 100 to obtain new voltage simulation results until the new voltage simulation result shows that the simulated voltage meets the withstand requirements of the SVG connected reactor.

[0027] This embodiment determines the actual reactive power and intermediate parameters of the SVG by setting the reactive power control target of SLCC, the harmonic control target of SVG, and the initial reactor parameters. This transforms the SLCC system requirements into specific equipment parameters. The total output current and voltage of the SVG, used to obtain the current margin coefficient, are then determined based on these specific equipment parameters. The current margin ensuring safe system operation is obtained through output calculation. Finally, simulation verification forms a feedback and adjustment closed loop, iteratively optimizing and determining the optimal reactor parameters. This invention, through equipment parameter calculation, simulation verification, and a feedback and adjustment closed loop to determine the optimal reactor parameters, improves the stability of the SLCC system and the accuracy of reactor parameter selection while matching the SLCC system requirements.

[0028] See Figure 2 , Figure 2This is a flowchart illustrating another embodiment of the method for determining the steady-state parameters of the SVG-connected reactor in SLCC provided by the present invention, as shown below. Figure 2 As shown, this embodiment is a further refinement of step 200 above, including steps 210 to 240, each of which is detailed below: Step 210: Determine the SVG harmonic control target based on the SLCC topology; Step 220: Determine the fundamental current of the SVG based on the actual reactive power of the SVG and the intermediate parameters; Step 230: Based on the SVG harmonic control target and the SVG fundamental current, determine the total output current and total output voltage of the SVG; Step 240: Determine the current margin coefficient based on the initial parameters of the reactor, the total output current of the SVG, and the total output voltage of the SVG.

[0029] Determining the harmonic control target of SVG based on the SLCC topology is a systematic decision-making process, which can be summarized as follows: (1) Analyze the harmonic sources. Based on the pulsation number of the LCC converter valve in the SLCC topology (e.g., 6 pulsations), determine its inherent characteristic harmonic spectrum (6k±1). (2) Make trade-offs. A balance is achieved between filtering effect, system cost and complexity. If the ultimate harmonic control effect is pursued and cost is not a concern, compensation for all characteristic harmonics can be selected. If economy is pursued, a hybrid filtering scheme of passive filter + SVG is adopted, with SVG responsible for higher-order harmonics.

[0030] In this embodiment, the output current of the actual SVG branch and the output voltage of the SVG are calculated based on the harmonic current of the converter station. The total harmonic compensation capability of the SVG includes two parts: one part is the voltage capability required for the absorption current of the SVG branch, and the other part is the voltage capability required for the natural shunt through the bridge arm reactor.

[0031] The total output current of the SVG is calculated as follows: (This is based on the actual reactive power output of the SVG.) and SVG grid connection point voltage Determine the fundamental current of the SVG As shown in Formula 1, calculate the current naturally shunted to the SVG branch. As shown in Formula 2, where, The impedance of the SVG connection impedance branch; Harmonic currents shunted by natural impedance; The impedance of the statcom vargeneration (SVG) is given.

[0032] (1) (2) SVG total output current The calculation is shown in Formula 3, where, Related to the SVG control objective and the SVG natural impedance shunt characteristics, It is the lowest frequency harmonic of the natural shunting.

[0033] (3) The total output voltage of the SVG is calculated as follows: the total output voltage of the SVG is the superposition of three parts: the voltage required for target harmonic compensation, the voltage generated by natural shunt harmonics, and the highest voltage on the valve side. The voltage required for target harmonic compensation... The calculation is shown in Formula 4, where, Related to the SVG control objective, it refers to the harmonics under the SVG control objective. It is the lowest harmonic under the control target; It is the highest harmonic under the SVG control target.

[0034] (4) (5) (6) Voltage generated by natural harmonic shunting The calculation is shown in Formula 5, where, It is the highest harmonic under the control target. SVG total output voltage. The calculation is shown in Formula 6, where, This is the highest voltage on the valve side.

[0035] In this embodiment, the stress in the SVG of the SLCC system comes not only from actively compensated harmonics, but also from natural shunting caused by impedance relationships. Through this refined stress calculation, the technical effects of suppressing harmonic losses, preventing equipment overstress, and ensuring equipment lifespan are achieved.

[0036] In another embodiment of the method for determining the steady-state parameters of the SVG-connected reactor in SLCC provided by the present invention, step 300 specifically includes: Step 310: If the current margin coefficient is not within the preset range, adjust the initial parameters of the reactor and return to the step of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor. Step 320: If the current margin coefficient is within the preset range, then based on the SLCC reactive power control target, the initial parameters of the reactor, and the voltage of the SVG connected reactor, the voltage simulation result is obtained.

[0037] Assume the rated engineering voltage of the submodule is Then the number of submodules The current margin under transient conditions at this time The calculation is shown in Formula 7, where, for; These are the initial parameters of the reactor; This represents the valve control response time. Formula 7 is used to evaluate whether the IGBT devices in the SVG arm have sufficient current safety margin during a severe transient fault in the system. The numerator represents the actual safe current capacity available to the IGBT during the fault, calculated by subtracting the unavailable current increment caused by the valve terminal voltage in the reactor and control delay from the theoretical maximum available current of the IGBT. The denominator represents the total peak current demand that the SVG branch needs to withstand during the fault. This is the ratio of available capacity to demand, where k>1 indicates a margin.

[0038] (7) When the initial parameters of the reactor are within the preset range If the current margin coefficient is within the preset range, it means that the initial parameters of the reactor can meet the system requirements; otherwise, if the current margin coefficient is not within the preset range, the initial parameters of the reactor are adjusted, and the process returns to step 100 above to re-iterate and calculate the new current margin coefficient until the new current margin coefficient is within the preset range.

[0039] This embodiment links parameter selection with the transient safety and reliability of the system. A reasonable k value means that the IGBT has sufficient margin to avoid damage in the event of serious faults such as valve short circuits, thereby reducing the risk of commutation failure and ensuring the safe and stable operation of the system.

[0040] In another embodiment of the method for determining the steady-state parameters of the SVG-connected reactor in SLCC provided by the present invention, the step 300 above specifically includes: Step 500: If the voltage simulation result shows that the simulation voltage meets the withstand requirements of the SVG connected reactor, determine the initial parameters of the reactor as the steady-state parameters of the SVG connected reactor. Step 600: If the voltage simulation result shows that the simulated voltage does not meet the withstand requirements of the SVG connected reactor, adjust the SVG harmonic control target and return to the step of determining the SVG total output current and SVG total output voltage for obtaining the current margin coefficient based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters.

[0041] The calculation results were verified by establishing a detailed electromagnetic transient simulation model. The simulation simulates actual operating conditions, directly observing the voltage waveform and peak value across the reactor and comparing it with the theoretical calculation value. If the simulation results show that the equipment's voltage withstand capability is limited (i.e., the simulated voltage does not meet the withstand requirements of the SVG connected reactor), it is necessary to return to adjust the SLCC's control target and reactor parameters to re-simulate the voltage across the reactor.

[0042] This embodiment verifies the correctness of the above calculations through simulation and provides the basis for final optimization.

[0043] In another embodiment of the method for determining the steady-state parameters of the SVG-connected reactor in SLCC provided by the present invention, step 400 specifically includes: Step 410: After adjusting the SVG harmonic control target based on the voltage simulation results, if the updated simulation voltage meets the withstand requirement, then the initial parameters of the reactor are determined to be the steady-state parameters of the SVG connected reactor. Step 420: After adjusting the SVG harmonic control target based on the voltage simulation results, if the updated simulation voltage does not meet the withstand requirements, adjust the initial parameters of the reactor and return to the step of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor.

[0044] The objectives of simulating the voltage of the SVG-connected reactor include verifying the accuracy of the theoretical model and determining... Whether it matches the simulation results. Directly observe equipment stress: intuitively obtain the dynamic voltage waveforms connected to the reactor terminals to confirm whether their peak values ​​and rates of change are within the equipment's tolerance capacity. Expose potential problems: discover abnormal transient processes (such as oscillations and overshoots) that the simplified theoretical model may not be able to predict. Provide the final basis for iterative optimization: simulation results are the standard for judging whether the reactor parameter selection is successful, and also the direct motivation for returning to adjust parameters and control objectives (such as harmonic compensation order) if necessary.

[0045] The voltage simulation process described above is as follows: 1. Build a model including the SLCC converter valve, converter transformer, SVG branch (including the connecting reactor with parameters to be determined), control system, and AC system; 2. Simulation operating conditions: Set typical system operating conditions and disturbance scenarios, such as 1.0 pu single-pole full-voltage high-end valve group operation; the control objective is to achieve 0% reactive power and harmonic suppression on the converter transformer side; the simulation events are: SVG starts at 0.5 seconds, with 6k±1 harmonic compensation enabled by default; high-precision waveform recording begins at 15 seconds; and at 16 seconds, the harmonic control objective is switched from filtering 6k±1 harmonics to filtering 12k±1 harmonics. By switching the harmonic control objective, the difference in reactor voltage stress under different objectives is compared to verify the rationality of the objective selection.

[0046] 3. Key Waveform Observation and Data Extraction: Observe and record the waveform data of the connected reactor voltage, SVG valve-side voltage, key system node voltages, and current and power. The peak voltage of the connected reactor needs to be accurately measured; the SVG valve-side voltage is used to assess the voltage stress of the SVG itself; the key system node voltages, currents, and power are used to verify whether the overall system operation is normal. 4. Comparison and Analysis of Simulation Results and Theoretical Calculations: Compare the simulated peak voltages with... By comparison, if the peak voltage measured by simulation is... If the values ​​are basically consistent and lower than the rated insulation levels of the reactor and SVG equipment, it indicates that the reactor parameters have been selected correctly. Conversely, if the values ​​are not consistent, it indicates that the reactor parameters have been selected incorrectly.

[0047] This embodiment demonstrates through simulation that filtering out specific harmonics can reduce voltage stress, providing a direct basis for optimizing the selection of reactor parameters for greater economy and reliability.

[0048] The steady-state parameter determination system for the SVG-connected reactor of SLCC provided by the present invention will be described below. The steady-state parameter determination system for the SVG-connected reactor of SLCC described below can be referred to in correspondence with the steady-state parameter determination method for the SVG-connected reactor of SLCC described above.

[0049] Please refer to Figure 3 The present invention also provides a system for determining the steady-state parameters of an SVG-connected reactor in a SLCC, comprising: The SLCC system parameter determination module 301 is used to determine the actual reactive power and intermediate parameters of the static var generator (SVG) based on the reactive power control target of the SLCC phase converter in the cascaded power grid and the initial parameters of the reactor. The SVG total output determination module 302 is used to determine the SVG total output current and SVG total output voltage for obtaining the current margin coefficient based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters. Voltage simulation module 303 is used to determine the voltage simulation results of the SVG connected reactor based on the current margin coefficient; The reactor parameter adjustment module 304 is used to adjust the initial parameters of the reactor and return to the steps of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor after adjusting the SVG harmonic control target based on the voltage simulation results and if the updated voltage simulation results do not meet the preset requirements.

[0050] Optionally, the SVG total output determination module includes: An SVG harmonic control target determination unit is used to determine the SVG harmonic control target based on the SLCC topology. The SVG fundamental current determination unit is used to determine the SVG fundamental current based on the actual reactive power of the SVG and the intermediate parameters. The SVG total output power determination unit is used to determine the SVG total output current and SVG total output voltage based on the SVG harmonic control target and the SVG fundamental current. The current margin coefficient determination unit is used to determine the current margin coefficient based on the initial parameters of the reactor, the total output current of the SVG, and the total output voltage of the SVG.

[0051] Optionally, the voltage simulation module includes: The reactor initial parameter adjustment unit is used to adjust the reactor initial parameters and return the steps of determining the actual reactive power and intermediate parameters of SVG based on the SLCC reactive power control target and the reactor initial parameters if the current margin coefficient is not within the preset range. The voltage simulation unit is used to simulate the voltage of the SVG-connected reactor based on the SLCC reactive power control target, the initial parameters of the reactor, and if the current margin coefficient is within a preset range, and to obtain the voltage simulation results.

[0052] Optionally, the SLCC's SVG-connected reactor steady-state parameter determination system further includes: The steady-state parameter determination module is used to determine the initial parameters of the reactor as the steady-state parameters of the SVG-connected reactor when the voltage simulation result shows that the simulation voltage meets the withstand requirements of the SVG-connected reactor. The SVG harmonic control target adjustment module is used to adjust the SVG harmonic control target when the voltage simulation result shows that the simulated voltage does not meet the withstand requirements of the SVG connected reactor, and to return the steps of determining the SVG total output current and SVG total output voltage for obtaining the current margin coefficient based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters.

[0053] Optionally, the reactor parameter adjustment module includes: The steady-state parameter determination unit is used to determine the initial parameters of the reactor as the steady-state parameters of the SVG connected reactor if the updated simulation voltage meets the tolerance requirement after adjusting the SVG harmonic control target based on the voltage simulation results. The reactor parameter adjustment unit is used to adjust the initial parameters of the reactor and return to the steps of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor after adjusting the SVG harmonic control target based on the voltage simulation results and if the updated simulation voltage does not meet the withstand requirements.

[0054] 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 determining the steady-state parameters of an SVG-connected reactor in a single-cell capacitor bank (SLCC), characterized in that, include: Based on the reactive power control target of the SLCC phase converter in the cascaded power grid and the initial parameters of the reactor, the actual reactive power and intermediate parameters of the static var generator (SVG) are determined. Based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters, the total output current and total output voltage of the SVG used to obtain the current margin coefficient are determined. The voltage simulation results of the SVG-connected reactor are determined based on the current margin coefficient. After adjusting the SVG harmonic control target based on the voltage simulation results, if the updated voltage simulation results do not meet the preset requirements, the initial parameters of the reactor are adjusted and the process of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor is returned.

2. The method for determining the steady-state parameters of the SVG-connected reactor in SLCC as described in claim 1, characterized in that, The determination of the total SVG output current and total SVG output voltage for obtaining the current margin coefficient, based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters, includes: Determining SVG harmonic control targets based on SLCC topology; The fundamental current of the SVG is determined based on the actual reactive power of the SVG and the intermediate parameters. Based on the SVG harmonic control target and the SVG fundamental current, determine the SVG total output current and the SVG total output voltage; The current margin coefficient is determined based on the initial parameters of the reactor, the total output current of the SVG, and the total output voltage of the SVG.

3. The method for determining the steady-state parameters of the SVG-connected reactor in SLCC as described in claim 1, characterized in that, The voltage simulation results for determining the SVG-connected reactor based on the current margin coefficient include: If the current margin coefficient is not within the preset range, then adjust the initial parameters of the reactor and return to the steps of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor; If the current margin coefficient is within the preset range, then based on the SLCC reactive power control target, the initial parameters of the reactor, and the voltage of the SVG connected reactor, the voltage simulation results are obtained.

4. The method for determining the steady-state parameters of the SVG-connected reactor in SLCC as described in claim 1, characterized in that, The voltage simulation results of the SVG connected reactor determined based on the current margin coefficient include: If the voltage simulation result shows that the simulation voltage meets the withstand requirements of the SVG-connected reactor, the initial parameters of the reactor are determined to be the steady-state parameters of the SVG-connected reactor. If the voltage simulation result shows that the simulated voltage does not meet the withstand requirements of the SVG connected reactor, the SVG harmonic control target is adjusted, and the steps for determining the SVG total output current and SVG total output voltage for obtaining the current margin coefficient are returned based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters.

5. The method for determining the steady-state parameters of the SVG-connected reactor in SLCC as described in claim 4, characterized in that, After adjusting the SVG harmonic control target based on the voltage simulation results, if the updated voltage simulation results do not meet the preset requirements, the initial parameters of the reactor are adjusted and the process of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor is returned. After adjusting the SVG harmonic control target based on the voltage simulation results, if the updated simulation voltage meets the withstand requirement, then the initial parameters of the reactor are determined to be the steady-state parameters of the SVG connected reactor. After adjusting the SVG harmonic control target based on the voltage simulation results, if the updated simulation voltage does not meet the withstand requirement, the initial parameters of the reactor are adjusted and the process of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor is returned.

6. A system for determining the steady-state parameters of an SVG-connected reactor in a SLCC, characterized in that, include: The SLCC system parameter determination module is used to determine the actual reactive power and intermediate parameters of the Static Var Generator (SVG) based on the reactive power control target of the SLCC phase-commutator in the cascaded power grid and the initial parameters of the reactor. The SVG total output determination module is used to determine the SVG total output current and SVG total output voltage for obtaining the current margin coefficient based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters. The voltage simulation module is used to determine the voltage simulation results of the SVG connected reactor based on the current margin coefficient. The reactor parameter adjustment module is used to adjust the initial parameters of the reactor and return the steps of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor after adjusting the SVG harmonic control target based on the voltage simulation results and if the updated voltage simulation results do not meet the preset requirements.

7. The steady-state parameter determination system for the SVG-connected reactor of SLCC as described in claim 6, characterized in that, The SVG total output determination module includes: An SVG harmonic control target determination unit is used to determine the SVG harmonic control target based on the SLCC topology. The SVG fundamental current determination unit is used to determine the SVG fundamental current based on the actual reactive power of the SVG and the intermediate parameters. The SVG total output power determination unit is used to determine the SVG total output current and SVG total output voltage based on the SVG harmonic control target and the SVG fundamental current. The current margin coefficient determination unit is used to determine the current margin coefficient based on the initial parameters of the reactor, the total output current of the SVG, and the total output voltage of the SVG.

8. The steady-state parameter determination system for the SVG-connected reactor of SLCC as described in claim 6, characterized in that, The voltage simulation module includes: The reactor initial parameter adjustment unit is used to adjust the reactor initial parameters and return the steps of determining the actual reactive power and intermediate parameters of SVG based on the SLCC reactive power control target and the reactor initial parameters if the current margin coefficient is not within the preset range. The voltage simulation unit is used to simulate the voltage of the SVG-connected reactor based on the SLCC reactive power control target, the initial parameters of the reactor, and if the current margin coefficient is within a preset range, and to obtain the voltage simulation results.

9. The steady-state parameter determination system for the SVG-connected reactor of SLCC as described in claim 6, characterized in that, The steady-state parameter determination system for the SVG-connected reactor of the SLCC also includes: The steady-state parameter determination module is used to determine the initial parameters of the reactor as the steady-state parameters of the SVG-connected reactor when the voltage simulation result shows that the simulation voltage meets the withstand requirements of the SVG-connected reactor. The SVG harmonic control target adjustment module is used to adjust the SVG harmonic control target when the voltage simulation result shows that the simulated voltage does not meet the withstand requirements of the SVG connected reactor, and to return the steps of determining the SVG total output current and SVG total output voltage for obtaining the current margin coefficient based on the SVG harmonic control target, the actual reactive power of the SVG, and the intermediate parameters.

10. The steady-state parameter determination system for the SVG-connected reactor of SLCC as described in claim 9, characterized in that, The reactor parameter adjustment module includes: The steady-state parameter determination unit is used to determine the initial parameters of the reactor as the steady-state parameters of the SVG connected reactor if the updated simulation voltage meets the tolerance requirement after adjusting the SVG harmonic control target based on the voltage simulation results. The reactor parameter adjustment unit is used to adjust the initial parameters of the reactor and return to the steps of determining the actual reactive power and intermediate parameters of the SVG based on the SLCC reactive power control target and the initial parameters of the reactor after adjusting the SVG harmonic control target based on the voltage simulation results and if the updated simulation voltage does not meet the withstand requirements.

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