Short-circuit ratio adaptive wave impedance matching method for gil-aerial hybrid line

Abstract

This application discloses an adaptive impedance matching method for short-circuit ratio in GIL-overhead hybrid lines, belonging to the field of power system technology. This method calculates the real-time short-circuit ratio by collecting voltage and current phasors at the connection point; calculates a weighting factor based on the real-time short-circuit ratio and a threshold comparison, dynamically generating a two-stage target impedance; calculates the target inductance value and integrates GIL parasitic capacitance compensation to calculate the target capacitance value; converts the parameters into control commands to drive the actuator adjustment, and performs hysteresis comparison and voltage verification. This invention achieves an adaptive balance between precise matching of strong grids and voltage stability in weak grids by dynamically adjusting LC parameters based on the real-time short-circuit ratio. It utilizes a two-stage LC structure to suppress overvoltage and integrates parasitic capacitance to optimize volume and cost. The hysteresis and voltage verification mechanisms avoid frequent operation, improving system stability and equipment lifespan, providing a solution that balances insulation protection and transmission capacity for hybrid lines.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and specifically to a short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines. Background Technology

[0002] With the rapid development of society and the economy, the demand for power transmission continues to grow. In power projects with limited space, high reliability, or stringent environmental requirements, such as those in complex and steep mountainous areas and densely populated urban areas, segmented heterogeneous hybrid transmission systems, consisting of alternating connections of multiple overhead lines and multiple gas-insulated transmission lines, can effectively solve the challenges of power transmission under constrained conditions. These hybrid lines typically exhibit a configuration where the transmission line transitions from an overhead line to a gas-insulated transmission line tunnel and back to an overhead line, or even more complex multi-segment coupling patterns. However, this multi-segment heterogeneous topology introduces multiple points of impedance discontinuity with varying properties into the system.

[0003] The significant difference in surge impedance between overhead lines and gas-insulated transmission lines, coupled with the multiple reflections and superpositions of traveling waves at alternating interfaces, makes overvoltage suppression and insulation coordination exceptionally complex. When lightning surges or switching overvoltage traveling waves propagate from overhead lines to gas-insulated transmission lines, severe traveling wave refraction and reflection occur at the common coupling point (CCP). This traveling wave refraction and reflection not only causes a sharp increase in the voltage gradient at the head end of the gas-insulated transmission line but may also lead to high-amplitude overvoltages due to the superposition of reflected waves. This seriously threatens the insulation safety of critical equipment such as insulators and bushings within the gas-insulated transmission line, affecting the stable and reliable operation of the hybrid transmission line.

[0004] Currently, there is no effective solution to the aforementioned impedance mismatch problem. In engineering practice, overhead lines and gas-insulated transmission lines are usually directly connected, or surge arresters are only installed at the head end of the gas-insulated transmission line for overvoltage protection. However, the function of surge arresters is limited to limiting the amplitude of overvoltage; they cannot fundamentally improve the traveling wave oscillation problem caused by impedance mismatch, nor can they reduce the steepness of the traveling wave front, making it difficult to completely eliminate the threat to the insulation of gas-insulated transmission line equipment.

[0005] Existing theoretical research has proposed achieving smooth impedance transition by connecting a fixed inductor in series at the connection point. However, this approach has significant limitations in adaptability to different operating conditions. In weak power grids, i.e., under low short-circuit ratio conditions, a large-resistance series inductor introduces a significant power frequency voltage drop, leading to a decrease in line transmission capacity and, in severe cases, even voltage collapse, threatening system voltage stability. The parameters of existing matching devices are fixed according to specific operating conditions. When changes occur in the power grid operation, such as generator disconnection, line maintenance, or severe load fluctuations causing changes in system short-circuit capacity, the fixed-parameter matching device cannot adaptively adjust. This not only makes it difficult to guarantee impedance matching effectiveness but may also become a weak link in the system, triggering new power grid safety issues such as subsynchronous oscillations.

[0006] Existing technical solutions lack real-time sensing capabilities for grid strength, making it difficult to achieve an effective balance between impedance matching accuracy and system voltage stability. While some adjustable matching schemes possess some adjustment capabilities, they employ only simple threshold switching logic. This leads to frequent switching of actuators even with minor fluctuations in grid parameters, resulting in a significant "ping-pong effect." This effect not only causes excessive wear on mechanical components such as circuit breakers and inductor taps but also introduces secondary transient impacts due to repeated switching, further deteriorating system transient characteristics and potentially causing safety hazards such as subsynchronous oscillations. Summary of the Invention

[0007] This invention provides a short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines, which solves the problems of existing hybrid line wave impedance matching schemes being unable to adaptively adjust according to grid strength and being difficult to balance overvoltage suppression and system voltage stability.

[0008] This invention is achieved through the following technical solution:

[0009] In a first aspect, this application provides a short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines, comprising the following steps:

[0010] Real-time acquisition of voltage and current phasors at the point of common coupling; calculation of system equivalent impedance and short-circuit capacity based on impedance definition; output of real-time dynamic short-circuit ratio.

[0011] The real-time dynamic short-circuit ratio is compared with the preset strong grid threshold and weak grid threshold to determine the system operating condition and calculate the weighting factor;

[0012] Based on the real-time grid strength, the ideal matching impedance and voltage support safety impedance are linearly fused using the calculated weighting factor as coefficients, thereby adaptively and dynamically generating the target wave impedance with a two-stage gradient transition.

[0013] Combining the target wave impedance and wave impedance formula, the target inductance value is calculated, and the target capacitance value is calculated by integrating the parasitic capacitance parameters of the GIL terminal bushing.

[0014] The target parameter value is converted into a control command to drive the actuator to adjust the parameters, and hysteresis comparison and voltage deviation verification are performed based on the real-time short-circuit ratio fluctuation and the steady-state voltage monitoring results of the point of common coupling; wherein, the target parameter value is the target inductance value and the target capacitance value.

[0015] A further optimization scheme is that the weighting factor is calculated as follows:

[0016] When the real-time system short-circuit ratio is greater than the strong power grid threshold, the weighting factor takes the first preset value;

[0017] When the real-time system short-circuit ratio is less than the weak grid threshold, the weighting factor takes the second preset value;

[0018] When the short-circuit ratio of the real-time system is between two thresholds, the weighting factor is calculated by linear interpolation.

[0019] Wherein, the first preset value is greater than the second preset value, and the strong power grid threshold is greater than the weak power grid threshold.

[0020] A further optimized solution is that, under strong power grid conditions, the calculation formula for the target wave impedance is:

[0021] First-level target wave impedance:

[0022] ;

[0023] Second-stage matching target impedance:

[0024] ;

[0025] in, For OHL wave impedance, This is the GIL wave impedance.

[0026] A further optimization scheme is that the calculation of the target parameter value includes:

[0027] Based on the target wave impedance, the target inductance and target total capacitance of the matching network are calculated as shown in the following formula;

[0028] ;

[0029] In the formula, The target capacitance value, For the target wave impedance, This is the inductance value;

[0030] For the second-stage matching capacitor, the required external compensation capacitor value is... The calculation formula is shown below:

[0031] ;

[0032] In the formula, This is the value of the second-stage external compensation capacitor. This is the parasitic capacitance value.

[0033] The further optimized solution also includes the following steps:

[0034] Set a short-circuit ratio hysteresis dead zone. When the real-time system short-circuit ratio fluctuation is within the dead zone, maintain the current set values ​​of the adjustable inductor and adjustable capacitor unchanged.

[0035] The further optimized solution also includes the following steps:

[0036] Monitor the steady-state voltage at the point of common coupling. When the voltage deviation exceeds the limit, force parameter adjustment according to the weak grid mode.

[0037] A further optimization is that the calculation formula for the linear interpolation is:

[0038] ;

[0039] in, As the weighting factor, For the real-time system short-circuit ratio, For weak power grid threshold, This is the threshold for a strong power grid.

[0040] A further optimization is that the formula for calculating the target capacitance value is:

[0041] ;

[0042] in, The target capacitance value, This is the inductance value. The target wave impedance.

[0043] Secondly, this application provides a computer-readable storage medium storing a short-circuit ratio adaptive impedance matching program for a GIL-overhead hybrid line, wherein when the GIL-overhead hybrid line short-circuit ratio adaptive impedance matching program is executed by a processor, the steps of the GIL-overhead hybrid line short-circuit ratio adaptive impedance matching method as described above are implemented.

[0044] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0045] By monitoring the system's short-circuit ratio in real time and dynamically adjusting the LC parameters of the matching network based on weighting factors, an adaptive balance is achieved between precise impedance matching under strong grid conditions and prioritizing voltage stability under weak grid conditions. This method effectively suppresses overvoltages caused by traveling wave reflections using a two-stage LC gradient transition structure, while optimizing device size and cost by integrating the parasitic capacitance of the GIL (Gas Inlet Isolation System) bushing. The built-in hysteresis comparison and voltage feedback verification mechanisms prevent frequent actuator operations, significantly improving system transient stability and equipment lifespan, and providing a solution for hybrid lines that balances insulation protection and transmission capacity under different operating conditions. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0047] In the attached diagram:

[0048] Figure 1 A flowchart of the short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines provided in this application embodiment;

[0049] Figure 2 This is a schematic diagram of the topology of the GIL-overhead hybrid line wave impedance matching system provided in the embodiments of this application;

[0050] Figure 3 A control flowchart of the GIL-overhead hybrid line impedance matching method based on short-circuit ratio adaptive adjustment provided in the embodiments of this application;

[0051] Figure 4 Impedance transition characteristic curves of GIL-overhead hybrid line adaptive adjustment under different operating conditions provided in the embodiments of this application;

[0052] Figure 5 is a waveform comparison diagram of the implementation effect provided in the embodiments of this application. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are only for explaining this invention and are not intended to limit this invention.

[0054] First, some of the technical terms used in this application will be explained to help those skilled in the art understand this application.

[0055] GIL: Gas Insulated Line;

[0056] OHL: Overhead Line;

[0057] PCC: Point of Common Coupling;

[0058] SCR: Short Circuit Ratio;

[0059] PT: Potential Transformer;

[0060] CT: Current Transformer;

[0061] DSP: Digital Signal Processor;

[0062] FPGA: Field Programmable Gate Array;

[0063] TCR: Thyristor Controlled Reactor;

[0064] LC: Inductor-Capacitor;

[0065] Firstly, such as Figure 1 As shown, this application provides a short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines, including the following steps:

[0066] Step S1: Real-time acquisition of voltage and current phasors at the point of common coupling, calculation of the system's equivalent impedance and short-circuit capacity based on the impedance definition, and output of the real-time dynamic short-circuit ratio;

[0067] Step S2: Compare the real-time dynamic short-circuit ratio with the preset strong grid threshold and weak grid threshold to determine the system operating condition and calculate the weighting factor;

[0068] Step S3: Based on the real-time grid strength, the ideal matching impedance and voltage support safety impedance are linearly fused using the calculated weighting factor as coefficients, thereby adaptively and dynamically generating the target wave impedance with a two-stage gradient transition.

[0069] Step S4: Combine the target wave impedance and wave impedance formula to calculate the target inductance value, and integrate the parasitic capacitance parameters of the GIL terminal bushing to calculate the target capacitance value.

[0070] Step S5: Convert the target parameter value into a control command to drive the actuator to adjust the parameters, and perform hysteresis comparison and voltage deviation verification based on the real-time short-circuit ratio fluctuation and the steady-state voltage monitoring results of the point of common coupling; wherein, the target parameter value is the target inductance value and the target capacitance value.

[0071] This embodiment achieves intelligent coordination between impedance matching effect and system stability by dynamically adjusting matching parameters based on real-time grid strength and short-circuit ratio. It effectively overcomes the inherent defect of fixed-parameter matching devices' insufficient adaptability to changes in grid operating conditions. Specifically, under strong grid conditions, it prioritizes smooth impedance transition to suppress overvoltage traveling waves, while under weak grid conditions, it automatically prioritizes voltage stability, thus avoiding the risk of power frequency voltage drops caused by excessively large series inductors. Furthermore, the introduced hysteresis comparison and voltage feedback verification mechanism effectively filters out signal fluctuation interference, suppresses frequent actuator movements, ensures stable and reliable control, suppresses overvoltage amplitude and wavefront steepness at mixed line connection points, reduces the risk of insulation breakdown in GIL equipment, and effectively reduces the configuration capacity of external capacitors by utilizing the inherent parasitic capacitance of the GIL terminal bushing, combining transient overvoltage suppression capability with good engineering economy.

[0072] In one embodiment, step S1: Real-time acquisition of voltage and current phasors at the point of common coupling, calculation of the system's equivalent impedance and short-circuit capacity based on impedance definition, and output of real-time dynamic short-circuit ratio, specifically includes the following steps:

[0073] Step S11: Synchronously acquire the instantaneous values ​​of three-phase voltage and current at the point of common coupling (PCC) and convert them into voltage phasor Ū and current phasor Ī. Specifically, at the PCC of the overhead line (OHL) and gas-insulated transmission line (GIL), i.e., the electrical connection point between the line input and the first-level matching branch, arrange voltage transformers (PT) and current transformers (CT). The specific topological location and electrical connection relationship of this acquisition point are as follows: Figure 2 As shown, the instantaneous values ​​of the three-phase voltage and current at this point are acquired in real time using a synchronous phasor acquisition method and converted into synchronous voltage phasors U and current phasors I. The acquired phasor data is transmitted to the computing unit after synchronous processing. This not only provides accurate basic data for the real-time calculation of the system short-circuit ratio (SCR), but also identifies the direction of the traveling wave at the instant of lightning surge by sensing the transient voltage / current change rate, thereby providing a criterion for subsequent inductor tap latching or pre-adjustment within milliseconds.

[0074] Step S12: Based on the obtained voltage and current phasors, calculate the system's equivalent impedance using the following impedance definition formula. The imaginary part of the calculation result is taken as the inductive impedance component, and the equivalent impedance of the system is output. :

[0075] ;

[0076] Step S13: Combine the effective value of the bus voltage |U| and the system equivalent impedance The real-time system short-circuit capacity is calculated according to the following formula. :

[0077] ;

[0078] In the formula, the effective value of the bus voltage |U| is calculated from the voltage phasor Ū.

[0079] Step S14: Combine short-circuit capacity and the rated transmission power of hybrid lines Calculate the real-time dynamic short-circuit ratio As shown in the following formula:

[0080] .

[0081] This embodiment constructs a closed-loop feedback foundation for dynamically sensing the operating status of the power grid through high-precision synchronous phasor acquisition and real-time calculation. It provides real-time and accurate quantitative indicators of power grid strength, namely the dynamic short-circuit ratio SCR(t), for subsequent adaptive matching control. The acquired data can also instantly identify the direction of traveling waves during transient processes, such as when lightning waves intrude, providing key criteria for millisecond-level pre-adjustment or protection locking of the matching network. Thus, it realizes the dual-function integration from steady-state monitoring to transient response, improving the sensing speed, control accuracy, and dynamic response capability of the entire system.

[0082] In one embodiment, the adaptive adjustment control logic for the short-circuit ratio is as follows: Figure 3 As shown, step S2, which compares the real-time dynamic short-circuit ratio with preset strong grid thresholds and weak grid thresholds to determine the system operating condition and calculate the weighting factor, specifically includes the following steps:

[0083] Step S21: Preset strong grid threshold and weak grid threshold, compare the real-time dynamic short-circuit ratio with the two thresholds, obtain the preliminary operating mode determination result of the system, and calculate the weighting factor ω; specifically, the strong grid threshold is set to 3.0, and the weak grid threshold is set to 2.0; further, it includes the following steps:

[0084] Step S22A: When When the system is in a strong grid mode, the weighting factor is set to the first preset value, for example, ω=1.

[0085] Step S22B: When When the weighting factor takes the second preset value, the system voltage support capability is weak, the control objective is set to "voltage stability first, with filtering as a secondary consideration", and the system is determined to be in a weak grid mode, for example, ω=0;

[0086] Step S22C: When When the system is in transition mode, it is determined that it is in transition mode. To avoid sudden parameter changes at critical operating conditions, a linear interpolation algorithm is used to calculate the weighting factor ω to achieve a smooth transition between strong and weak power grid modes. The calculation formula is shown below:

[0087]

[0088] Wherein, the first preset value is greater than the second preset value, and the strong power grid threshold is greater than the weak power grid threshold.

[0089] This embodiment accurately quantifies and determines the system operating condition by comparing the real-time dynamic short-circuit ratio with preset strong and weak grid thresholds, and calculates the weighting factor accordingly, thus achieving adaptive switching of control objectives: in strong grid mode, priority is given to ensuring impedance matching accuracy to optimize traveling wave suppression; in weak grid mode, voltage stability is prioritized to avoid introducing excessive inductive reactance; in transition mode, a linear interpolation algorithm is used to dynamically calculate the ω value, thereby completely avoiding parameter jumps and system oscillations caused by sudden changes in control objectives at critical operating points, ensuring a smooth and stable transition between different modes, and enhancing the overall adaptability and reliability of the system.

[0090] In one embodiment, step S3: based on the real-time grid strength, using the calculated weighting factor as coefficients, linearly fuses the ideal matching impedance and the voltage support safety impedance to adaptively and dynamically generate the target wave impedance with a two-stage gradient transition, specifically including the following steps:

[0091] Step S31: Based on overhead line surge impedance Surge impedance of gas-insulated transmission lines Based on the principle of geometric series gradient transition, the ideal matching impedance of the two stages is calculated. and The calculation formula is as follows:

[0092]

[0093]

[0094] In the formula, Z OHL For the OHL wave impedance, Z GIL For GIL wave impedance; To match the target impedance for the first stage, The target impedance is matched for the second stage.

[0095] This calculation is based on the principle of geometric series gradient transition, ensuring that the wave impedance decreases in a stepwise manner from OHL to GIL, achieving a perfect transition;

[0096] Step S32: Considering the voltage stability constraints under weak grid conditions, determine the two-stage safety impedance that can ensure the voltage stability at the point of common coupling by setting the maximum allowable series reactance value. and This safety impedance is set to ensure voltage stability under weak power grid conditions. It reduces the power frequency voltage drop by limiting the series inductance value and is suitable for scenarios with weak power grid strength where voltage stability must be given priority.

[0097] Step S33: Introduce a weighting factor ω to weight and fuse the ideal matching impedance and the safety impedance, dynamically generating a two-level target wave impedance adapted to the current system strength. Further, this includes the following steps:

[0098] When the power grid is a strong grid (ω=1), the control objective prioritizes ensuring impedance matching accuracy. In this case, the target impedance is entirely determined by the ideal matching impedance sequence:

[0099]

[0100]

[0101] When the power grid is weak (ω=0), the control objective prioritizes ensuring voltage stability. In this case, the target impedance is entirely determined by the voltage-supported safety impedance sequence:

[0102]

[0103]

[0104] When the power grid is in a transitional state (0 < ω < 1), to avoid abrupt parameter changes and achieve a smooth transition, the target impedance is calculated through linear interpolation:

[0105]

[0106]

[0107] In the formula, For the first-order target impedance, This is the second-level target impedance.

[0108] This embodiment introduces a weighting factor as a linear fusion coefficient to dynamically weight and fuse the ideal matching impedance calculated based on the geometric series gradient transition principle with the safety impedance considering voltage stability constraints. This allows for the adaptive generation of a two-stage gradient transition target impedance based on real-time grid strength. Under strong grid conditions, this method prioritizes impedance matching accuracy to optimize traveling wave suppression; under weak grid conditions, it automatically prioritizes voltage stability to mitigate power frequency voltage drop risks. Furthermore, under transitional conditions, linear interpolation enables smooth switching of control targets, effectively avoiding parameter jumps and system oscillations caused by changes in operating conditions or threshold critical points. This fundamentally improves the adaptability of impedance matching and the overall system operational stability.

[0109] In one embodiment, step S4: combining the target wave impedance and the wave impedance formula to calculate the target inductance value, and integrating the GIL terminal bushing parasitic capacitance parameter compensation to calculate the target capacitance value, specifically includes the following steps:

[0110] Step S41: The controller determines the target wave impedance based on the two levels. and The corresponding inductive reactance components are used to output commands to adjust the first-stage adjustable inductor. Second-stage adjustable inductor The tap position is chosen to bring the inductance close to the target value. The adjustment strategy is related to the weighting factor:

[0111] Under strong power grid operating conditions (ω=1), in order to achieve the best matching effect, increase and The amount of input;

[0112] Under weak grid conditions (ω=0), in order to prioritize voltage stability and reduce... The amount of input is used to reduce the power frequency voltage drop;

[0113] Under the transient condition (0<ω<1), the inductance is linearly adjusted with the value of ω to achieve a smooth transition.

[0114] Step S42: Based on the target wave impedance and the adjusted inductance value, process and calculate the two-stage target capacitance values, and integrate the parasitic capacitance for compensation adjustment. Further, this includes the following steps:

[0115] The capacitor and inductor values ​​are adjusted in tandem to ensure impedance matching, and this is achieved through two independent control stages:

[0116] Step S421: Based on the first-level target wave impedance and the regulated inductor For the first stage capacitor Adjustments are made, and the target capacitance value is calculated:

[0117]

[0118] The controller enables the switching of parallel capacitor banks to The actual value approaches the target value. The switching strategy corresponds to inductor adjustment: reduce [inductance] during strong grid conditions. Increase input during weak power grid periods Input amount.

[0119] Step S422: For the second stage capacitor Adjustments and parasitic capacitance compensation are performed, specifically as follows:

[0120] Based on the second-level target wave impedance and the regulated inductor Calculate the total demand capacitance for the second stage. :

[0121]

[0122] Introducing the inherent parasitic capacitance of the GIL termination bushing This value is determined through preliminary experiments or simulations, and the required external compensation capacitor value is calculated. :

[0123]

[0124] The controller only controls the input capacitance value of the external capacitor bank that requires external compensation. This will satisfy the total capacitance requirement;

[0125] This embodiment uses a weighting factor to guide the adaptive adjustment of the two-stage inductor's operating conditions in real time, and on this basis, it collaboratively calculates the target values ​​of the two-stage capacitors. In particular, it integrates and utilizes the inherent structural parasitic capacitance of the GIL terminal bushing. This collaborative adjustment mechanism not only strictly ensures the dynamic establishment of the wave impedance matching relationship, but also reduces the capacity requirement of external compensation capacitors by effectively utilizing existing parasitic capacitances. Thus, while ensuring impedance matching accuracy, it achieves a reduction in overall device cost and optimization of space layout.

[0126] In one embodiment, step S5: converting the target parameter value into a control command drives the actuator to adjust the parameters, and performing hysteresis comparison and voltage deviation verification based on real-time short-circuit ratio fluctuation and steady-state voltage monitoring results at the point of common coupling; wherein, the target parameter value is the target inductance value and the target capacitance value, specifically including the following steps:

[0127] Step S51: Convert the target inductance and capacitance parameters into specific action commands for the corresponding actuators, including digital control commands such as the target position of the inductor tap and the switching combination of the capacitor bank;

[0128] Step S52: Determine whether the real-time short-circuit ratio fluctuation of the system continuously exceeds the preset dead zone range through hysteresis comparison logic. Parameter adjustment permission is triggered only when this condition is met.

[0129]

[0130] Set the SCR hysteresis dead zone ΔSCR = ±0.05. When the fluctuation amplitude of SCR(t) is within the dead zone, parameter adjustment is not triggered; only when... Only when the dead zone is exceeded will the weight factor be recalculated and the parameters adjusted to prevent the actuator from experiencing micro-tremors due to minor fluctuations.

[0131] Step S53: When the adjustment conditions are met, the digital control command is converted into the corresponding pulse width modulation signal or switch signal to drive the vacuum circuit breaker to adjust the inductor tap position, or to control the thyristor firing angle to switch the capacitor bank.

[0132] Step S54: After parameter adjustment, continuously monitor the steady-state voltage at the point of common coupling. When a voltage deviation exceeding a safety threshold (e.g., 5%) is detected, the protection logic is immediately triggered, forcibly setting the weighting factor to zero and recalculating the safety parameters to prioritize system voltage stability. Here, the safety parameters refer to the upper limit of matching network parameters set to prioritize voltage stability under weak grid conditions. Specifically, this is manifested as the maximum allowable series inductance value and its corresponding voltage-supporting safety impedance under weak grid conditions.

[0133] The physical implementation principle of adjustable inductor and adjustable capacitor actuators is as follows: Figure 4 As shown. In terms of physical implementation, the adjustable inductor uses a stepped tapped air-core reactor, equipped with a vacuum circuit breaker or a high-power thyristor (using TCR technology) as a switching switch to achieve millisecond-level inductor parameter switching. The adjustable capacitor uses a grouped capacitor bank, with switching controlled by a vacuum contactor. Signal synchronization adopts synchronous phasor acquisition technology, and the adaptive controller uses a DSP+FPGA hardware architecture with a control cycle of no more than 10ms to ensure real-time performance.

[0134] This embodiment effectively filters out minute fluctuations in the real-time short-circuit ratio through hysteresis comparison logic, preventing oscillations in the actuator due to frequent actions near the critical threshold and ensuring the smoothness of the control process. At the same time, by continuously monitoring the voltage at the point of common coupling and performing deviation verification, the protection logic can be quickly triggered when the voltage is abnormal, forcing the system to switch to a safety mode that prioritizes voltage stability. This provides a reliable double guarantee for the system voltage stability during dynamic parameter adjustment, significantly enhancing the robustness and safety margin of the overall control.

[0135] Figure 5(a) shows the waveform distribution of overvoltage when closing a hybrid transmission line without any impedance matching measures.

[0136] Figure 5(b) shows the waveform of the overvoltage distribution when the hybrid transmission line is closed after adopting the interpolation adjustment scheme of the present invention;

[0137] Figure 5(c) shows the lightning overvoltage distribution waveform at the connection of the hybrid transmission line when no impedance matching measures are used.

[0138] Figure 5(d) shows the lightning overvoltage distribution waveform at the connection of the hybrid transmission line after adopting the interpolation adjustment scheme of the present invention.

[0139] As shown in Figure 5, the effectiveness of the short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines provided in this application is visually verified through four sets of waveform comparison experiments: Figure 5(a) shows the overvoltage distribution waveform at the end of the hybrid transmission line under closing operation without any wave impedance matching measures. Its high peak value and significant oscillation characteristics reflect the insulation risk of the traditional direct connection method. After applying the interpolation adjustment scheme of this invention under the same conditions, Figure 5(b) shows that the peak value of closing overvoltage is reduced by 53%, and the waveform is significantly smoother, demonstrating the advantage of suppressing switching overvoltage. Corresponding to the lightning impulse condition, Figure 5(c) presents the lightning overvoltage waveform at the line connection point (PCC) without matching measures. The steep wavefront and high voltage peak highlight the threat of traveling wave reflection. Figure 5(d) shows that after adopting the method of this invention, the peak value of lightning overvoltage is reduced by 44%, and the wavefront steepness is effectively alleviated, proving its dual advantages in suppressing transient overvoltage and protecting GIL insulation. The waveform comparison of the implementation effect of this method with that of the traditional unmatched scheme intuitively demonstrates its significant advantages in suppressing closing overvoltage and lightning overvoltage.

[0140] Secondly, this application provides a short-circuit ratio adaptive wave impedance matching system for GIL-overhead hybrid lines, comprising:

[0141] The sensor acquisition module is used to acquire voltage and current phasors at the point of common coupling in real time, calculate the equivalent impedance and short-circuit capacity of the system based on the impedance definition, and output the real-time dynamic short-circuit ratio.

[0142] The data calculation module is connected in communication with the sensor acquisition module and is used to compare the real-time dynamic short-circuit ratio with the preset strong power grid threshold and weak power grid threshold to determine the system operating condition and calculate the weighting factor.

[0143] The operating condition determination module communicates with the data calculation module and is used to linearly fuse the ideal matching impedance and voltage support safety impedance based on the real-time power grid strength and the calculated weight factor as coefficient, thereby adaptively and dynamically generating the target wave impedance of the two-level gradient transition.

[0144] The impedance generation module is communicatively connected to the operating condition determination module. It is used to calculate the target inductance value by combining the target wave impedance and the wave impedance formula, and to calculate the target capacitance value by integrating the parasitic capacitance parameters of the GIL terminal bushing.

[0145] The instruction conversion and execution module is communicatively connected to the impedance generation module. It is used to convert the target parameter values ​​into control instructions, drive the actuator to adjust the parameters, and perform hysteresis comparison and voltage deviation verification based on the real-time short-circuit ratio fluctuation and the steady-state voltage monitoring results of the point of common coupling. The target parameter values ​​are the target inductance value and the target capacitance value.

[0146] The functions of each module in the GIL-overhead hybrid line short-circuit ratio adaptive wave impedance matching system mentioned above correspond to the steps in the GIL-overhead hybrid line short-circuit ratio adaptive wave impedance matching method embodiment mentioned above. Their functions and implementation processes will not be described in detail here.

[0147] Thirdly, embodiments of this application provide a short-circuit ratio adaptive impedance matching device for GIL-overhead hybrid lines. The short-circuit ratio adaptive impedance matching device for GIL-overhead hybrid lines can be a personal computer (PC), laptop computer, server, or other device with data processing capabilities.

[0148] In this embodiment of the application, the short-circuit ratio adaptive wave impedance matching device for GIL-overhead hybrid lines may include a processor, a memory, a communication interface, and a communication bus.

[0149] The communication bus can be of any type and is used to interconnect the processor, memory, and communication interface.

[0150] The communication interface includes input / output (I / O) interfaces, physical interfaces, and logical interfaces. These interfaces are used for interconnecting devices within the GIL-overhead hybrid line short-circuit ratio adaptive impedance matching device, and for interconnecting the GIL-overhead hybrid line short-circuit ratio adaptive impedance matching device with other devices (such as other computing devices or user equipment). Physical interfaces can be Ethernet interfaces, fiber optic interfaces, ATM interfaces, etc.; user equipment can be displays, keyboards, etc.

[0151] Memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), etc.

[0152] The processor can be a general-purpose processor, which can call the GIL-overhead hybrid line short-circuit ratio adaptive impedance matching program stored in memory and execute the GIL-overhead hybrid line short-circuit ratio adaptive impedance matching method provided in the embodiments of this application. For example, the general-purpose processor can be a central processing unit (CPU). The method executed when the GIL-overhead hybrid line short-circuit ratio adaptive impedance matching program is called can refer to the various embodiments of the GIL-overhead hybrid line short-circuit ratio adaptive impedance matching method of this application, and will not be repeated here.

[0153] Fourthly, embodiments of this application also provide a readable storage medium.

[0154] This application stores a short-circuit ratio adaptive impedance matching program for GIL-overhead hybrid lines on a readable storage medium, wherein when the short-circuit ratio adaptive impedance matching program for GIL-overhead hybrid lines is executed by a processor, the steps of the short-circuit ratio adaptive impedance matching method for GIL-overhead hybrid lines as described above are implemented.

[0155] The method implemented when the GIL-overhead hybrid line short-circuit ratio adaptive wave impedance matching procedure is executed can be referred to in the various embodiments of the GIL-overhead hybrid line short-circuit ratio adaptive wave impedance matching method of this application, and will not be repeated here.

[0156] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines, characterized in that, Includes the following steps: Real-time acquisition of voltage and current phasors at the point of common coupling; calculation of system equivalent impedance and short-circuit capacity based on impedance definition; output of real-time dynamic short-circuit ratio. The real-time dynamic short-circuit ratio is compared with the preset strong grid threshold and weak grid threshold to determine the system operating condition and calculate the weighting factor; Based on the real-time grid strength, the ideal matching impedance and voltage support safety impedance are linearly fused using the calculated weighting factor as coefficients, thereby adaptively and dynamically generating the target wave impedance with a two-stage gradient transition. Combining the target wave impedance and wave impedance formula, the target inductance value is calculated, and the target capacitance value is calculated by integrating the parasitic capacitance parameters of the GIL terminal bushing. The target parameter value is converted into a control command to drive the actuator to adjust the parameters, and hysteresis comparison and voltage deviation verification are performed based on the real-time short-circuit ratio fluctuation and the steady-state voltage monitoring results of the point of common coupling; wherein, the target parameter value is the target inductance value and the target capacitance value.

2. The short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines according to claim 1, characterized in that, The weighting factor is calculated as follows: When the real-time system short-circuit ratio is greater than the strong power grid threshold, the weighting factor takes the first preset value; When the real-time system short-circuit ratio is less than the weak grid threshold, the weighting factor takes the second preset value; When the short-circuit ratio of the real-time system is between two thresholds, the weighting factor is calculated by linear interpolation. Wherein, the first preset value is greater than the second preset value, and the strong power grid threshold is greater than the weak power grid threshold.

3. The short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines according to claim 1, characterized in that, Under strong power grid conditions, the formula for calculating the target wave impedance is: First-level target wave impedance: ； Second-stage matching target impedance: ； in, For OHL wave impedance, This is the GIL wave impedance.

4. The short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines according to claim 1, characterized in that, The calculation of the target parameter value includes: Based on the target wave impedance, the target inductance and target total capacitance of the matching network are calculated as shown in the following formula; ； In the formula, The target capacitance value, For the target wave impedance, This is the inductance value; For the second-stage matching capacitor, the required external compensation capacitor value is... The calculation formula is shown below: ； In the formula, This is the value of the second-stage external compensation capacitor. This is the parasitic capacitance value.

5. The short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines according to claim 1, characterized in that, It also includes the following steps: Set a short-circuit ratio hysteresis dead zone. When the real-time system short-circuit ratio fluctuation is within the dead zone, maintain the current set values ​​of the adjustable inductor and adjustable capacitor unchanged.

6. The short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines according to claim 1, characterized in that, It also includes the following steps: Monitor the steady-state voltage at the point of common coupling. When the voltage deviation exceeds the limit, force parameter adjustment according to the weak grid mode.

7. The short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines according to claim 2, characterized in that, The formula for calculating the linear interpolation is: ； in, As the weighting factor, For the real-time system short-circuit ratio, For weak power grid threshold, This is the threshold for a strong power grid.

8. The short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines according to claim 4, characterized in that, The formula for calculating the target capacitance value is as follows: ； in, The target capacitance value, This is the inductance value. The target wave impedance.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a short-circuit ratio adaptive wave impedance matching program for GIL-overhead hybrid lines, wherein when the short-circuit ratio adaptive wave impedance matching program for GIL-overhead hybrid lines is executed by a processor, it implements the steps of the short-circuit ratio adaptive wave impedance matching method for GIL-overhead hybrid lines as described in any one of claims 1 to 8.

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