A high-power contactless module switch capable of monitoring capacitor decay

Abstract

The present application relates to the technical field of intelligent power grid reactive power compensation equipment, and particularly relates to a high-power contactless module switch capable of monitoring capacitor attenuation, comprising a thyristor switching module, a current sampling module and a control module, the control module synchronously samples line current and extracts fundamental wave reactive component based on capacitor switching events, separates current response caused by target capacitor input from line background dynamic change through constructing a response analysis process corresponding to the switching events, obtains independent fundamental wave reactive response quantity corresponding to the target capacitor, and calculates capacitor attenuation state parameters in combination with rated output capacity; meanwhile, switching control of the capacitor participating in reactive power compensation is constrained and adjusted based on the attenuation state parameters, the module switch has both no-inrush quick switching and capacitor state online monitoring capabilities, and can be applied to dynamic reactive power compensation scenes in complex power grid environment, and is beneficial to improving reactive power compensation accuracy and compensation device operation reliability.

Description

Technical Field

[0001] This invention relates to the field of reactive power compensation equipment for smart grids, and more specifically to a high-power contactless module switch capable of monitoring capacitor attenuation. Background Technology

[0002] In low-voltage dynamic reactive power compensation systems, thyristor-based contactless switching modules are typically used to quickly switch capacitor banks, improving the reactive power compensation response speed and reducing the impact and wear caused by mechanical contacts. With the widespread application of nonlinear loads such as metallurgy, electric arc furnaces, new energy grid connection, or charging stations, capacitors are prone to capacity decay after long-term operation due to the influence of harmonics in the power grid and load fluctuations, affecting the reactive power compensation effect. Therefore, some contactless compensation systems introduce online capacitor status monitoring functions and estimate capacitor capacity based on the current changes before and after switching.

[0003] Existing technologies typically collect current data before and after a capacitor is switched on and extract the corresponding fundamental component to calculate the actual output current of the capacitor, thereby determining whether the capacitor is degrading. However, during the thyristor switching process, the capacitor is prone to short-term transient response at the moment of switching on, which causes fluctuations in the fundamental component of the current collected shortly after switching. Especially under dynamic load or harmonic environments, this fluctuation can cause the calculated capacitor output current to deviate from the capacitor's true reactive power output capacity, resulting in distorted capacitor degradation assessment results. In severe cases, it may lead to the compensation system misjudging the capacitor's health status. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention discloses a high-power contactless module switch capable of monitoring capacitor degradation. The aim is to achieve rapid switching of capacitor banks without inrush current while simultaneously monitoring and evaluating the capacity degradation status of capacitors during operation. This improves the accuracy of capacitor degradation identification in complex power grid environments and uses the monitoring results for control and regulation of capacitor participation in reactive power compensation, taking into account reactive power compensation response speed, compensation accuracy, and long-term operational reliability of the compensation device.

[0005] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution: A high-power contactless modular switch for monitoring capacitor attenuation includes a thyristor switching module, a current sampling module, and a control module. The thyristor switching module is used for contactless switching of capacitor banks, and the control module is used to perform the following processing steps: During the operation of the target capacitor, the line current sampling signal of the current sampling module is acquired, and the current characteristic quantity reflecting the change of the line fundamental reactive power is extracted. The specific extraction process includes: performing synchronous phase locking on the line current sampling signal to obtain the synchronous phase angle corresponding to the grid fundamental voltage. The synchronous phase locking adopts a digital phase-locked loop to track the fundamental voltage phase in real time. Based on the synchronous phase angle, the line current sampling signal is transformed to a synchronous rotating coordinate system to obtain the direct-axis current component and the quadrature-axis current component; The cross-axis current component is used as the fundamental reactive current characteristic quantity corresponding to the target capacitor; When the target capacitor is switched, the corresponding switching trigger time is used as the event reference time to construct a response analysis window for the current characteristic quantity that is synchronized with the switching event; and the change response sequence is calculated based on the current characteristic quantity corresponding to the continuous power frequency cycle within the response analysis window. Based on the temporal correlation between the change response sequence and the event reference time, the event response component caused by the switching of the target capacitor in the change response sequence is identified and separated from the dynamic change component of the line background to obtain the independent fundamental reactive power response quantity corresponding to the target capacitor. The actual reactive power output capacity of the target capacitor is calculated based on the independent fundamental reactive power response, and compared with the rated output capacity to obtain the attenuation state parameters of the target capacitor. The switching control of the target capacitor in reactive power compensation is adjusted based on the attenuation state parameters.

[0006] Furthermore, the process by which the control module calculates the changing response sequence based on the current characteristic quantities corresponding to continuous power frequency cycles within the response analysis window includes: The response analysis window is divided into multiple continuous complete power frequency cycles, and the fundamental reactive current characteristic quantity corresponding to each power frequency cycle is extracted respectively. ,in, This indicates the power frequency cycle number based on the starting position of the response; The center period is the power frequency period at which the target capacitor is switched on / off. The fundamental reactive current characteristic quantities corresponding to multiple power frequency cycles before and after the center cycle are obtained respectively; for any power frequency cycle Calculate the corresponding change response value using the following formula: in, Indicates the first The change response value corresponding to each power frequency cycle; Indicates the first The fundamental reactive current characteristic quantity corresponding to each power frequency cycle; and They represent the first The fundamental reactive current characteristic quantities corresponding to the first and last power frequency cycles. Arrange the change response values ​​in order of power frequency cycle. This forms the change response sequence.

[0007] Furthermore, the control module adjusts the switching control of the target capacitor participating in reactive power compensation through hierarchical constraint processing, including: After the target capacitor is taken out of operation, the control module calculates the number of switching lock-in cycles corresponding to the target capacitor based on the attenuation state parameters. The target capacitor is prohibited from being put back into operation within the specified number of switching lockout cycles; the specified number of switching lockout cycles The calculation formula is: in, This indicates the number of switching lock-up cycles corresponding to the target capacitor; This represents the response bias weighting coefficient; This represents the cumulative weighting coefficient for the switching action; Indicates the target capacitor number The independent fundamental reactive power response corresponding to each monitoring step; Indicates the target capacitor number The rated reactive power output capacity corresponding to the next monitoring step; Indicates the cumulative number of times the target capacitor has been switched on and off; This indicates the number of monitoring sessions included in the statistical calculations; After the switching lockout period ends, the control module allows the target capacitor to re-participate in the reactive power compensation switching control.

[0008] Furthermore, after the target capacitor stops operating, the control module continuously collects the voltage across the target capacitor. and the voltage connected to the bus. When satisfied When this occurs, the target capacitor is allowed to enter the next switching monitoring cycle; wherein, This represents the voltage difference tolerance factor, and ; If the above conditions are not met, the control module keeps the target capacitor in the exit state and suspends the update of the decay state parameters of the target capacitor.

[0009] Based on the above technical solution, the positive and beneficial effects of the present invention are as follows: 1. This invention enables online identification of the attenuation state of the target capacitor during contactless dynamic reactive power compensation operation, and accurately reflects the output state of the target capacitor when it actually participates in reactive power compensation. By analyzing the response of the line current around the capacitor switching event, the fundamental reactive power response caused by the target capacitor switching is extracted from the overall dynamic changes of the line, so that the obtained capacitor response no longer depends on the direct comparison of the current before and after a single switching. Even under operating conditions with frequent load fluctuations or high harmonic content, it can still effectively reduce the influence of transient response and background disturbance on the detection results, and improve the stability and accuracy of capacitor attenuation assessment results.

[0010] 2. This invention links the capacitor status monitoring results with the reactive power compensation switching control process. While performing reactive power compensation, the compensation system has the ability to continuously sense the capacitor's operating status. Based on the identified attenuation status parameters, the capacitor's participation in the compensation process can be dynamically constrained, so that each capacitor branch takes into account both compensation capability and operating status during long-term operation. This helps to slow down the continuous performance degradation of the capacitor caused by frequent switching, and improves the rationality of capacity utilization and long-term operational stability of the compensation system.

[0011] 3. This invention can complete capacitor status identification, attenuation assessment and control linkage based on the original sampling link and control unit of the contactless module. There is no need to configure an additional independent detection branch or dedicated detection equipment. It is easy to deploy and implement directly in existing low-voltage dynamic reactive power compensation devices. It takes into account monitoring accuracy, control real-time performance and engineering feasibility. It can reduce the cost of later maintenance and manual inspection. It has good engineering application value for improving the operational reliability and service life of high-power contactless compensation devices. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a flowchart illustrating the control principle of the control module of the present invention. Figure 2 This is a schematic diagram of the module switch system framework of the present invention; Figure 3 This is a schematic diagram illustrating the response analysis of capacitor switching events based on the present invention; Figure 4 This is a schematic diagram of the thyristor switching module connection of the present invention; Figure 5 This is a schematic diagram illustrating the working principle of the present invention; Figure 6 This is a waveform diagram of the target capacitor being engaged in the present invention; Figure 7 This is a schematic diagram of the spectrum analysis of the line current corresponding to the target capacitor switching event in this invention; Figure 8 This is a schematic diagram of the process for extracting the independent fundamental reactive response in this invention. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0014] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0015] The present invention describes the specific application environment architecture or specific hardware architecture of a high-power contactless module switch capable of monitoring capacitor attenuation. The high-power contactless module switch capable of monitoring capacitor attenuation described in the present invention can be applied in low-voltage or medium-voltage dynamic reactive power compensation cabinets, serving as a switching execution unit between capacitor banks and power supply busbars, and connected to a three-phase reactive power compensation system to perform rapid contactless switching of capacitor banks and monitoring of capacitor operating status.

[0016] Specifically, please see Figure 2 The high-power contactless module switch includes a housing, a main circuit board located inside the housing, and a thyristor switching module, a control module, a current sampling module, and auxiliary control circuits mounted on the main circuit board. The top of the housing has three-phase input terminals, corresponding to phases L1, L2, and L3, for connection to the compensation cabinet busbar. The bottom of the housing has three-phase output terminals, corresponding to phases L4, L5, and L6, for connection to the target capacitor bank. The three-phase input terminals are connected to the three-phase output terminals via the thyristor switching module to form the main power circuit for the target capacitor bank to connect to the power grid. (See also...) Figure 4As shown, the thyristor switching module adopts a three-phase independent switching structure, including thyristor power branches corresponding to phases A, B, and C respectively. Each thyristor power branch is connected in series between the corresponding phase's grid input terminal and the capacitor bank. Each thyristor power branch is electrically connected to the control module, which outputs trigger pulses to control its conduction or cutoff. In this embodiment, the thyristor power branches preferably adopt an anti-parallel thyristor structure to meet the AC bidirectional conduction requirement. When the control module outputs a conduction trigger signal, the corresponding thyristor power branch conducts, the capacitor bank is connected to the grid, and participates in reactive power compensation; when the control module stops outputting the trigger signal, the thyristor is turned off. The capacitor bank exits the compensation circuit. Furthermore, the thyristor switching module can also be connected to a zero-crossing detection unit. The control module determines the trigger time based on the zero-crossing detection signal, causing the thyristor to conduct near the voltage zero-crossing position to reduce the inrush current generated at the moment the capacitor is switched on and improve the stability of the switching process. The input side of the thyristor switching module is connected to the power supply bus, and the output side is connected to the target capacitor bank. After receiving the trigger signal output by the control module, the target capacitor bank is put into operation by turning on the corresponding thyristor, and is taken out of operation by triggering its turn-off. The control module is installed in the middle area of ​​the main circuit board and can be implemented using an MCU controller, DSP controller, or FPGA controller. Its input terminals are connected to the current sampling module and the zero-crossing detector, respectively, and its output terminals are connected to the trigger, protection circuit, and status indication circuit, respectively. The control module receives the switching on or off control command sent by the compensation controller and outputs the corresponding thyristor trigger control signal in conjunction with the zero-crossing detection signal.

[0017] Furthermore, the zero-crossing detector is connected to the three-phase AC bus voltage sampling terminal to detect the zero-crossing position of the three-phase AC voltage and output a zero-crossing synchronization signal to the control module; the trigger is connected to the control module and the thyristor switching module to generate a corresponding gate drive pulse after the control module outputs the trigger control signal and apply it to the thyristor gate to control the thyristor to conduct near the corresponding voltage zero-crossing point. The thyristor synchronous switching trigger control is a conventional implementation method in this field, and the prior art has been described in detail, so it will not be repeated here.

[0018] The current sampling module is located in the main power circuit and includes a current transformer and a current detection circuit connected thereto. The current transformer is mounted on the three-phase incoming circuit or the three-phase outgoing circuit and is used to collect the line operating current after the target capacitor is connected to the bus. The current detection circuit includes a signal conditioning circuit, a sample-and-hold circuit, and an analog-to-digital conversion circuit, which are used to perform proportional transformation, filtering, isolation, and digital sampling on the output signal of the current transformer, and transmit the corresponding line current sampling signal to the control module.

[0019] In some specific embodiments, the auxiliary control circuit further includes a rectifier power supply module, a protection module, a temperature control module, and a heat dissipation module. The rectifier power supply module is connected to an external AC auxiliary power supply, and after rectification and voltage regulation, supplies power to the control module, trigger, and detection circuit. The protection module is connected to both the control module and the thyristor switching module, and is used to perform overcurrent protection, overvoltage protection, and overtemperature protection. The temperature control module includes a temperature control switch and a temperature detection device, used to detect the temperature rise of the thyristor heat sink substrate. When the detected temperature reaches the corresponding threshold, the fan is started to provide forced air cooling for the thyristor heat sink. In some implementation scenarios, the high-power contactless module switch may also include an energy recovery branch, which is connected to the output side of the thyristor switching module. This branch is used to release or feed back the residual energy stored in the target capacitor after the target capacitor bank is taken out of operation, reducing the impact of residual capacitor voltage on the subsequent switching process.

[0020] Based on the above hardware architecture, the control module in this embodiment not only undertakes the synchronous switching control of thyristors during the target capacitor bank's entry and exit process, but also undertakes line current sampling processing, capacitor status identification, and compensation control linkage functions. That is, the control logic in this invention is based on the original main power topology and detection circuit of the contactless module, and online monitoring of the capacitor's operating status can be achieved without the need to add an independent capacity detection branch.

[0021] Unlike existing dynamic reactive power compensation devices that directly calculate amplitude differences based on line current before and after capacitor switching, this embodiment does not directly use the instantaneous value of current sampling as the basis for determining capacitor capacity. Instead, it uses the thyristor triggering and conduction moment as the event reference benchmark. During the line response process corresponding to the target capacitor switching operation, it extracts current characteristic information that changes synchronously with the switching event and separates the independent fundamental reactive power response caused by the target capacitor switching from the total line current. This serves as the basis for calculating the actual reactive power output capacity of the capacitor. Thus, the contactless switching action simultaneously constitutes the capacitor state monitoring trigger source while completing the compensation execution function. The line operating current collected by the current sampling module serves as both the compensation current and the state identification analysis object. The control module completes the target capacitor attenuation state identification through correlation analysis between the switching event and the line response process, and further adjusts the switching control of the target capacitor participating in reactive power compensation based on the identification results. This makes the entire high-power contactless module switch a composite functional unit integrating inrush-free switching, state monitoring, and compensation control linkage.

[0022] Having understood the overall system architecture described above, the following will provide a more detailed description of the invention in conjunction with the accompanying drawings and specific implementation details. Specifically, a high-power contactless module switch capable of monitoring capacitor attenuation includes: a thyristor switching module, a current sampling module, and a control module. The thyristor switching module is used for contactless switching of capacitor banks. (See also...) Figure 1 and Figure 5 The control module is used to perform the following processing procedures: S100. During the operation of the target capacitor, the line current sampling signal of the current sampling module is acquired, and the current characteristic quantity reflecting the change of the fundamental reactive power of the line is extracted. In the specific system operation, the control module continuously receives the line current sampling signal from the current sampling module, and uses the target capacitor being in operation as the corresponding monitoring enable condition. It should be noted that the line current sampling signal comes from the current transformer set in the main power circuit and the current detection circuit connected to it. Its sampling object is the total line current after the target capacitor is connected to the power supply bus. As described above regarding the hardware connection relationship and signal acquisition process of the current sampling module, it will not be repeated here.

[0023] Since the total line current is simultaneously superimposed with the target capacitor output current, load variation current, and grid harmonic disturbance components, the control module does not directly use the instantaneous current value corresponding to the sampling time for subsequent calculations. Instead, it first extracts current characteristic quantities reflecting the fundamental reactive power change of the line from the line current sampling signal as the basis for subsequent analysis to identify the target capacitor switching response. Specifically, the control module first performs synchronous phase-locked loop processing on the line current sampling signal. In a preferred industrial embodiment, the control module calls a digital phase-locked loop to perform real-time phase tracking of the three-phase bus voltage to output a synchronous phase angle that changes synchronously with the current grid fundamental voltage. The synchronization phase angle is continuously updated with the change of the power grid frequency and serves as a unified angle reference for subsequent coordinate transformations. In another optional implementation, when the compensation system is configured with an independent voltage detection branch, synchronization phase locking can also be performed directly based on the voltage sampling signal. In some scenarios with high hardware cost requirements, phase synchronization correction can also be performed based on the thyristor zero-crossing synchronization signal recorded inside the control module. It should be understood that the above synchronization phase acquisition method is only used to provide a rotating reference coordinate synchronized with the fundamental wave of the power grid, and its specific implementation does not constitute a limitation on the core monitoring logic of this invention.

[0024] Obtaining the synchronization phase angle Subsequently, the control module transforms the line current sampling signal into a synchronous rotating coordinate system. In specific implementation, this is done using the three-phase current components corresponding to the line current sampling signal. As input, the direct-axis current component is obtained after Clarke and Park transforms. With cross-axis current component Its expression can be represented as: in, These represent the instantaneous currents of the three-phase lines, respectively. This represents the synchronization phase angle of the digital phase-locked loop output; This represents the direct-axis current component in a synchronously rotating coordinate system. This represents the quadrature-axis current component in a synchronously rotating coordinate system.

[0025] Furthermore, in a synchronous rotating coordinate system, the fundamental component of the line current is converted into a relatively stable DC component, while higher harmonics and asynchronous disturbances manifest as AC ripple components, facilitating the control module's extraction of the effective fundamental component. In this embodiment, the control module extracts the quadrature-axis current component... The fundamental reactive current characteristic quantity corresponding to the target capacitor is used because after the target capacitor is put into operation, its output reactive compensation current mainly manifests as the fundamental reactive component with a fixed phase relationship with the grid voltage, and is directly mapped to the quadrature axis direction in the synchronous rotating coordinate system. Correspondingly, the load active power fluctuation is mainly manifested in the direct axis direction, while the harmonic disturbance does not have a stable amplitude characteristic after coordinate transformation. Therefore, using the quadrature axis current component as the current characteristic quantity can decouple the fundamental reactive response generated by the target capacitor participating in compensation from the total line current without adding an additional detection branch, and effectively reduce the influence of harmonics and load dynamic fluctuations on the subsequent response identification process.

[0026] During implementation, the line current corresponding to the target capacitor switching process was further subjected to spectrum analysis, and the results are as follows: Figure 7 As shown, the control module performs frequency domain analysis on the line current collected by the current sampling module to obtain the spectral distribution of the line current at different frequency positions. The horizontal axis in the figure represents frequency, and the vertical axis represents the current amplitude at the corresponding frequency. Figure 7 It is known that the line current forms a significant peak frequency at the fundamental frequency position, while there are spectral components introduced by system background harmonics and load fluctuations in the higher frequency range. In this invention, the control module retains only the fundamental reactive component corresponding to the line current and suppresses the higher harmonic components by synchronous phase tracking and fundamental component extraction.

[0027] In more specific operating scenarios, such as when the three-phase load is unbalanced or the bus harmonic distortion rate is high, the control module can also adjust the output quadrature axis current component before outputting the quadrature axis current component. The power frequency periodic averaging filter or sliding filter is performed to further suppress sampling noise and high-frequency fluctuation components; its essence is still the extraction of the fundamental reactive component in the synchronous rotating coordinate system, so it does not affect the overall technical logic of the present invention to perform response analysis and attenuation state identification based on the current characteristic quantity.

[0028] S200: When the target capacitor is switched on or off, the corresponding switching trigger time is used as the event reference time to construct a response analysis window for the current characteristic quantity that is synchronized with the switching event; and the change response sequence is calculated based on the current characteristic quantity corresponding to the continuous power frequency cycle within the response analysis window. Specifically, the control module receives the thyristor gate trigger status signal from the trigger in real time and monitors the conduction state change of the thyristor corresponding to the target capacitor. When the control module outputs the target capacitor input command and the corresponding thyristor enters the conduction state, it obtains the trigger conduction signal of the thyristor corresponding to the target capacitor and records the corresponding thyristor conduction time. It should be noted that after the thyristor is turned on, although the target capacitor is connected to the main power circuit, there may be short-term transient current fluctuations in the line during the initial stage of conduction due to the instantaneous synchronization between the actual conduction position of the thyristor and the phase of the bus voltage. To avoid directly introducing the transient response generated at the moment of conduction into the subsequent analysis process, this embodiment does not directly use the thyristor conduction moment as the starting point of the analysis window. Instead, it further obtains the first zero-crossing point of the line voltage after the conduction moment and determines the first zero-crossing point as the response start position. That is, the control module converts the electrical triggering moment corresponding to the thyristor conduction action into a unified time reference position synchronized with the power frequency cycle, so that the starting point of the response analysis window is aligned with the boundary of the bus power frequency cycle. To illustrate the change in the electrical response of the line when the target capacitor is connected, taking phase A as an example, its waveform at the moment of switching is as follows: Figure 6 As shown in the figure, taking phase A as an example, the electrical response changes during the target capacitor connection process are illustrated. The horizontal axis represents time t, and the vertical dashed line corresponds to the switching trigger moment of the target capacitor. Before the switching trigger, phase A is in normal operation, and the line current and bus voltage remain stable. After the control module detects the connection command, it controls the thyristor switching module to conduct near the zero crossing of the corresponding phase voltage, so that the target capacitor is connected to the compensation circuit. At the moment the target capacitor is connected, the line current shows a short-term response change, and the capacitor terminal voltage transitions from the initial state to the steady-state operating value. Since the present invention adopts a thyristor contactless switching structure, the current change when the target capacitor is connected is a continuous change without obvious impact spikes, and the capacitor terminal voltage also maintains a smooth establishment process.

[0029] After obtaining the response start position, the control module adjusts the fundamental reactive current characteristic quantity according to the power frequency cycle. The system is continuously segmented, with the response start position as the segmentation starting point. Each power frequency cycle is then truncated into whole cycles. Specifically, the response start position is used as the zeroth cycle starting point, and multiple complete power frequency cycles are sequentially divided forward and backward according to the cycle length corresponding to the real-time grid frequency. Each power frequency cycle corresponds to an independent statistical interval for fundamental reactive current characteristics. Further, the control module selects multiple consecutive complete power frequency cycles before the response start position as the pre-switching response segment and multiple consecutive complete power frequency cycles after the response start position as the post-switching response segment. Subsequently, the pre-switching response segment and the post-switching response segment are concatenated end-to-end to form a response analysis window synchronized with the target capacitor switching event. The pre-switching response segment characterizes the fundamental reactive power change of the line under natural operating conditions before the target capacitor is switched on; the post-switching response segment characterizes the response change process of the total line current after the target capacitor is switched on. Both response segments are truncated in units of complete power frequency cycles, thus maintaining consistency in time scale and jointly forming a continuous event response observation interval around the response start position.

[0030] As a preferred industrial embodiment, the response segment before switching and the response segment after switching can each be selected as 3 to 8 complete power frequency cycles. The window length can also be dynamically adjusted according to the fluctuation of the compensation system. It should be understood that the number of power frequency cycles included in the response analysis window here is only an example to adapt to specific working conditions and does not constitute a limitation on the core processing logic of the present invention.

[0031] After constructing the response analysis window, the control module further calculates the changing response sequence based on the current characteristic quantities corresponding to the continuous power frequency cycles within the response analysis window. Specifically, the control module divides the response analysis window into multiple continuous complete power frequency cycles and extracts the fundamental reactive current characteristic quantities corresponding to each power frequency cycle. Furthermore, the control module uses the power frequency cycle in which the switching trigger time of the target capacitor occurs as the center cycle. Read the fundamental reactive current characteristic quantities corresponding to multiple power frequency cycles before and after the center cycle; for any power frequency cycle ,according to Calculate the corresponding change response value; in the specific calculation process, the above change response value In essence, it reflects the first The degree of local offset of a power frequency cycle relative to the preceding and following power frequency cycles, if the fundamental reactive power output changes significantly before and after the target capacitor is connected, then the corresponding power frequency cycle Abrupt changes will occur relative to its immediate preceding and following periods, thus affecting the response value. A local peak response is formed in the process; if there is only a slow load change in the line, the change trend between the previous and subsequent cycles tends to be continuous, and the change response value decreases accordingly; therefore, by comparing the current cycle with the adjacent previous and subsequent cycles locally, the sudden change in response caused by the switching of the target capacitor can be highlighted on a continuous power frequency scale, while suppressing the influence of slow fluctuations in the line background and low-frequency drift on the analysis results, making the change response sequence closer to the electrical response process corresponding to the switching event of the target capacitor itself. The control module arranges each change response value in the order of the power frequency cycle. The change response sequence is formed, which continuously corresponds to each power frequency cycle within the response analysis window along the time axis, and serves as the basic input for subsequent identification of the target capacitor switching event response component and separation of the dynamic change component of the line background.

[0032] S300. Based on the temporal correlation between the change response sequence and the event reference time, identify the event response component caused by the switching of the target capacitor in the change response sequence, and separate it from the dynamic change component of the line background to obtain the independent fundamental reactive power response quantity corresponding to the target capacitor. During implementation, the control module records the power frequency cycle corresponding to the event reference time as the center cycle, and reads the change response value cycle by cycle along both sides of the time axis based on the center cycle. The number of cycles read is kept consistent to ensure that a symmetrical data sequence is formed on both sides of the center cycle about the switching time. The change response values ​​at the same offset position on both sides of the center cycle are then paired sequentially, and a difference operation is performed. ,in, This is the offset of the power frequency cycle relative to the center cycle. To correspond to the changing response value of the power frequency cycle, that is, with the switching moment as the time axis, the changing response before and after the switching is compared cycle by cycle. This processing method is mainly based on the fact that before the target capacitor is connected, the reactive power change of the line is mainly determined by load fluctuations; after the target capacitor is connected, an additional response caused by the switching occurs in the line. If the line background is in a continuously changing state, the background change in adjacent cycles before and after the switching moment usually continues; while the response generated by the switching action is concentrated near the event reference moment. Therefore, the symmetrical position difference mainly retains the local response change corresponding to the switching event.

[0033] In actual operation, the control module arranges the timing difference values ​​corresponding to each offset position sequentially along the power frequency cycle direction, and slides along the change response sequence to extract a continuous power frequency cycle segment. For each power frequency cycle moved, the cumulative value of the absolute value of each timing difference value within that segment is calculated: in, To extract the number of power frequency cycles contained in the segment, As the starting power frequency cycle number of the corresponding segment, after the control module completes the calculation of all segments, it compares the cumulative values ​​and takes the continuous power frequency cycle segment corresponding to the smallest cumulative value as the event response segment corresponding to this switching. Here, "smallest" refers to the continuous time range in which the change trend before and after the switching is closest within the segment. In other words, within this time range, the changes in the line background have a high degree of continuity before and after the event, and the additional response caused by the switching of the target capacitor has stabilized and entered a recognizable state. Based on this, the control module uses the power frequency cycle segment as the time boundary for subsequent separation of event response components.

[0034] Under some operating conditions with rapid load fluctuations, the position of the event response section relative to the center cycle is allowed to have a certain offset; while when the bus is running relatively stably, the event response section is usually distributed near the center cycle; since the entire positioning process always takes the current thyristor switching time as the time reference and is completed cycle by cycle based on the actual collected change response sequence, positioning can be completed without the need to establish an additional fixed response model.

[0035] In this invention, the change response value within the event response section does not directly correspond to the actual output response of the target capacitor, but is the superposition result formed by the combined effect of the target capacitor switching response and the dynamic changes in the line background. Therefore, after completing the event response section positioning, the control module further introduces the background drift baseline to correct the change response value within the section.

[0036] Specifically, the background drift baseline is used to characterize the continuous drift trend of the fundamental reactive power change of the line within the event response section. It corresponds to the dynamic change of the line outside the current switching action of the target capacitor. This continuous drift trend mainly comes from load-side reactive power fluctuations, grid operating point offsets, or other compensation branch status changes. Since this part of the change usually exhibits continuous evolution within the event response section, the control module uses the change response value corresponding to the first power frequency cycle and the change response value corresponding to the last power frequency cycle of the event response section as the section boundary constraint, establishes a background drift baseline between the two, and uses it as an approximate characterization of the dynamic change component of the line background within this time range.

[0037] Furthermore, the corrected response value obtained by subtracting the background drift baseline from the change response value corresponding to each power frequency cycle within the event response segment can be understood as the net response change amount formed around this switching event. After this processing, the background drift component that changes slowly over time in the change response sequence is stripped away, and what is retained is the local response part that is synchronously associated with the target capacitor switching action.

[0038] Based on this, the control module performs a weighted summation of the correction response values ​​within the event response segment to obtain the event response component corresponding to the target capacitor. : in, The first in the event response segment The change response value corresponding to each power frequency cycle This represents the background drift baseline value corresponding to the power frequency cycle. The weighting coefficients corresponding to the power frequency cycle should be noted; it should be noted that the event response component... In this invention, the weighting coefficient is used to characterize the overall response contribution of a single switching action of the target capacitor on the fundamental reactive power component of the line. Numerically, it corresponds to the net increment of the fundamental reactive power change before and after the target capacitor is switched on. Since the response caused by the switching of the target capacitor is most concentrated near the event reference time, the weighting coefficient... The value decreases as the distance between the power frequency cycle and the event reference time increases, making the calculation results of the event response component closer to the main response corresponding to the current switching of the target capacitor.

[0039] The process of separating the event response component from the background dynamic change component in the change response sequence is as follows: Figure 8 As shown, the control module uses the target capacitor switching trigger moment as the event reference moment and uses multiple consecutive power frequency cycles before and after it as the response analysis window. The horizontal axis represents the power frequency cycle number, and the vertical axis represents the change response quantity corresponding to each power frequency cycle. Before the event reference moment, the change response sequence mainly reflects the background operating state of the line, and its fluctuations correspond to changes in system load and background disturbances in the power grid. After the target capacitor is switched on, the change response sequence shows a significant response shift near the event reference moment, which corresponds to the reactive power response change caused by the switching of the target capacitor. The control module further decomposes the change response sequence within the response analysis window, separating the slowly changing background dynamic component from the instantaneous response component caused by the switching event. The background dynamic component is used to characterize the line's background change trend, and the event response component is used to characterize the response contribution corresponding to the switching of the target capacitor. After separation, the event response component is accumulated to obtain the independent fundamental reactive power response quantity corresponding to the target capacitor. The independent fundamental reactive power response quantity is used to characterize the reactive power output capability corresponding to the actual operation of the target capacitor and serves as the input for subsequent calculation of capacitor attenuation state parameters.

[0040] In some more specific scenarios, event response components It still contains residual decaying oscillation components after the switching is completed. Based on this, the present invention further defines an event response boundary to limit the time endpoint of the effective response of the target capacitor.

[0041] The event response boundary is identified starting from the event reference time. The control module reads the correction response value corresponding to each power frequency cycle along the event response segment. When the product of the correction response values ​​corresponding to two adjacent power frequency cycles is less than zero for the first time, the corresponding position is determined as the event response boundary. This boundary corresponds to the position where the correction response value changes from the same direction to the opposite direction. Physically, it corresponds to the end position of the main response formed by the current switching of the target capacitor.

[0042] That is, the corrected response value from the event reference time to the event response boundary constitutes the effective response range corresponding to the current switching of the target capacitor; while the response changes after the event response boundary reflect the background adjustment process after the line re-enters steady state and are no longer included in the target capacitor response calculation range.

[0043] Please see Figure 3 The diagram shown illustrates the response analysis based on capacitor switching events. The control circuit uses the switching trigger time of the target capacitor. As a reference moment for the event, a reference window, a transition window, and a response window are divided on the time axis around the reference moment. The reference window is located before the target capacitor is connected and is used to collect the line phase current when the capacitor is not connected. The continuous waveform data is used as the baseline data for subsequent response analysis; the response window is located after the target capacitor is connected and is used to collect the line current changes after the capacitor is connected; the transition window is located between the two, corresponding to the short-time dynamic response stage after the thyristor turns on at zero crossing. The control circuit performs synchronous sampling of the line phase current collected in the reference window and the response window, and extracts the fundamental reactive current component in the corresponding power frequency cycle by combining the phase-locked loop tracking results. ,Depend on Figure 3 It can be seen that before the target capacitor is switched on, the fundamental reactive current component remains relatively stable; after the switching event occurs, the fundamental reactive current component changes as the target capacitor is connected to the line.

[0044] Based on this, the control circuit further performs differential calculations on the fundamental reactive current component corresponding to the continuous power frequency cycle to obtain the change response quantity. The change response quantity exhibits a significant response peak near the event reference time, and then gradually decays and stabilizes. The control circuit uses the change response quantity as a characterization of the target capacitor switching response, identifies the change response quantity corresponding to each power frequency cycle within the response window, and separates the event response component caused by the target capacitor switching from the dynamic change component of the line background, thereby obtaining the independent fundamental reactive power response quantity corresponding to the target capacitor, which is the correction response value corresponding to the event reference time and the event response boundary. The independent fundamental reactive power response quantity is the direct input quantity for subsequent calculation of the actual reactive power output capability of the target capacitor. It corresponds one-to-one with the thyristor switching action of the target capacitor in this operation and is distinguished from the dynamic change component of the line background.

[0045] S400. Calculate the actual reactive power output capacity of the target capacitor based on the independent fundamental reactive power response quantity, and compare it with the rated output capacity to obtain the attenuation state parameters of the target capacitor. The independent fundamental reactive power response quantity essentially corresponds to the effective fundamental reactive power response formed by a single switching action of the target capacitor on the line side. It should be noted that during engineering operation, capacitor capacity attenuation usually does not occur instantaneously, but is gradually accumulated with long-term switching, dielectric aging, and thermal stress cycles. Therefore, the actual reactive power output capacity of the target capacitor at the current moment is related not only to the independent fundamental reactive power response quantity corresponding to this switching, but also to its historical operating state. This invention introduces the historical operating state into the rated output capacity correction process through the cumulative number of switching operations, so as to match the attenuation assessment result with the actual operating conditions of the equipment.

[0046] In practical implementation, the control module tracks the cumulative number of switching operations on the target capacitor since it was put into operation. The cumulative switching count corresponds to the number of times the thyristor switching module completes effective conduction and forms a capacitor connected to the grid; the triggering process due to protection exit or failure to complete conduction is not included in the cumulative value.

[0047] Furthermore, the rated reactive power output capability of the target capacitor The rated reactive power output is the factory-specified value, reflecting the theoretical output capacity under the initial design conditions corresponding to rated voltage and frequency. Considering that the capacitor's parameters may change after long-term operation, the control module does not directly use this rated reactive power output capacity as a comparison benchmark, but rather dynamically corrects it based on the cumulative number of switching operations; the rated output capacity correction coefficient corresponding to each single switching operation... The expression used to describe the changing trend of the rated output capacity of a target capacitor under a unit number of switching operations is as follows: ,in, The target capacitor has been completed cumulatively. The baseline reactive power output capability after the second switching; The corresponding cumulative switching count, wherein the baseline reactive power output capacity is... This information can be obtained through periodic monitoring during equipment operation and maintenance, or by the control module updating records based on historical monitoring results. In some more specific scenarios, The corresponding test values ​​are the initial inspection values ​​after the equipment leaves the factory, the test values ​​during regular maintenance, or the stable statistical values ​​within the cumulative operating cycle; it should be understood that this refers to... The value selection method is only used to establish the correction relationship between the rated output capacity and the number of switching cycles, and does not constitute a limitation on the core monitoring logic of this invention.

[0048] Based on the correction coefficient The control module establishes a correction value for the current rated output capacity of the target capacitor and sets the independent fundamental reactive power response value. By comparing the modified rated output capability, the attenuation state parameters corresponding to the target capacitor are obtained. ,in, This is the independent fundamental reactive response quantity corresponding to the target capacitor; The attenuation state parameter, which characterizes the corrected rated output capability of the target capacitor at the current cumulative number of switching operations, is described in this invention. The attenuation state parameter characterizes the degree of deviation between the current actual reactive power output capability of the target capacitor and the theoretical output capability after the operation state correction. In other words, the attenuation state parameter reflects both the current switching response capability and the historical operating loss status of the target capacitor, rather than simply reflecting the instantaneous output change at a certain moment.

[0049] Compared to directly comparing with the factory rated value, this invention introduces the cumulative number of switching cycles as a correction factor, which transforms the evaluation object of the target capacitor's actual reactive power output capability from static rated parameters to a dynamic capability benchmark related to the equipment's operating life. As a result, the attenuation status parameters output by the control module can more accurately correspond to the current effective capacity status of the target capacitor that can participate in reactive power compensation.

[0050] S500. Adjust the switching control of the target capacitor for reactive power compensation according to the attenuation state parameter. It should be noted that the adjustment in this invention does not change the triggering logic of the thyristor switching module itself, but constrains the qualification of the target capacitor at the reactive power compensation control sequence level. That is, the control module still generates the compensation switching command according to the bus reactive power demand, but when it executes to the branch where the target capacitor is located, the attenuation state parameter is used as an additional criterion for the branch access judgment.

[0051] In practice, after the target capacitor has completed its shutdown, the control module calculates the number of switching lockout cycles corresponding to the target capacitor based on the historical monitoring results corresponding to the attenuation state parameters. The calculation formula is: in, Indicates the target capacitor number The independent fundamental reactive power response corresponding to each monitoring step. This indicates the rated reactive power output capacity at the corresponding monitoring time. This indicates the cumulative number of times the target capacitor has been switched on and off. This indicates the number of monitoring sessions included in the statistics. and These terms are used to adjust the response deviation and the cumulative switching impact ratio, respectively. In the formula, the first term reflects the cumulative deviation between the actual output capability and the theoretical output capability of the target capacitor; the second term introduces the impact of long-term switching conditions on the device's operating state. After the control module completes the calculation, it marks the target capacitor as locked and prohibits it from being put back into operation during the corresponding switching lock-up period.

[0052] In this invention, the switching lockout cycle corresponds to the adjustment cycle count of the compensation controller. After each reactive power compensation control cycle is completed, the control module decrements the lockout count. Once the count reaches zero, the lockout state is released, allowing the target capacitor to participate in subsequent compensation capacity allocation.

[0053] Furthermore, to prevent the target capacitor from being re-energized before its residual voltage has fully dissipated, the control module continuously monitors the voltage across its terminals after the target capacitor has been deactivated. and the voltage connected to the bus. When satisfied When the control module determines that the residual voltage across the target capacitor and the bus voltage have reached the allowable connection range, it allows the target capacitor to enter the next switching monitoring cycle; among which, The voltage difference tolerance factor has a value that satisfies... In some more specific engineering scenarios, It can be set according to the rated voltage level of the target capacitor, the bus voltage fluctuation range, and the thyristor withstand voltage margin.

[0054] If the above conditions are not met, the control module maintains the target capacitor in the deactivated state and suspends the update of the decay state parameters for that target capacitor. This setting is mainly due to the fact that the terminal voltage decay of the target capacitor after it is deactivated involves a discharge process. If it were to re-enter the switching control at this time, a large voltage difference could easily form at the moment the thyristor turns on, affecting the current sampling result and potentially interfering with subsequent decay state identification. Therefore, this invention uses voltage consistency judgment and switching lockout period together as the release conditions for the target capacitor to be re-engaged.

[0055] In other words, for a target capacitor to rejoin reactive power compensation, two conditions must be met simultaneously: first, the lockout period must end; second, the voltage at the target capacitor terminal and the bus voltage must meet the allowable connection conditions. Only when both conditions are met simultaneously, the control module releases the target capacitor from its exit state and restores its normal switching control in the compensation system. Thus, the attenuation state parameters obtained based on the independent fundamental reactive power response are not only used for capacitor health status assessment, but also directly participate in subsequent compensation control decisions, forming a closed-loop correlation between the target capacitor monitoring results and the branch switching control.

[0056] It should be noted that the target capacitor described in this invention can refer to a single compensation capacitor or a compensation branch unit composed of one or more capacitors. In a low-voltage dynamic reactive power compensation system, the target capacitor is typically connected to the compensation bus in the form of a capacitor bank via a thyristor switching module. The control module establishes corresponding event reference times, response analysis windows, and attenuation state parameters for each thyristor switching module. In scenarios with multiple branches operating in parallel, each branch completes monitoring calculations independently without affecting others; when multiple branches are put into operation sequentially, their respective thyristor conduction times are used as independent event references for processing. It should be understood that the specific capacity specifications, series-parallel connection forms, or wiring topologies of the target capacitor are only related to the on-site compensation capacity configuration and do not constitute a limitation on the monitoring logic of this invention.

[0057] The current sampling module is preferably located between the thyristor switching module and the compensation bus, and is used to collect the line current changes before and after the target capacitor is connected. In another optional hardware topology configuration, it can also be located on the main incoming line side of the compensation cabinet, and the switching response of each branch can be inverted by the change of the main bus current. For a three-phase compensation system, independent sampling loops can be configured for phases A, B and C respectively; alternatively, a unified sampling structure integrating three-phase current transformers can be used. The underlying mechanism for extracting the fundamental reactive power characteristics of the sampled current through synchronous rotating coordinate transformation has been described in detail above and will not be repeated here.

[0058] In addition, the event reference time in this invention comes from the conduction control signal output by the control module to the corresponding thyristor trigger. Therefore, it is a known control event that the control module can directly obtain, rather than being calculated in reverse based on the change of current waveform. That is, the control module records the corresponding timestamp at the same time as outputting the trigger command and associates it with the subsequent sampled data. This design ensures that the response analysis window and the actual switching action maintain the same time base, thereby ensuring that the independent fundamental reactive power response can accurately correspond to the current switching behavior of the target capacitor.

[0059] In some more specific scenarios, when the protector detects overcurrent, overtemperature, or phase loss in the thyristor module, it can output a protection status signal to the control module. After receiving the protection status signal, the control module suspends the update of the attenuation status parameter corresponding to the current target capacitor and freezes the monitoring results, not including the switching process in the cumulative statistics. Correspondingly, when the temperature control switch detects that the radiator temperature has reached the set temperature rise threshold and drives the fan to run, the control module still maintains sampling operation, but can mark the corresponding thermal operation status in the record for subsequent historical monitoring data tracing. This part belongs to the supporting logic of the compensation module operation protection, which can further improve the adaptability of the present invention under high temperature, high harmonic and high frequency switching conditions.

[0060] To verify the practical application effect of the technical solution of the present invention, the applicant conducted a prototype test on a low-voltage reactive power compensation cabinet with a rated voltage of 400V and a rated capacity of 30kvar. The test objects included a high-power contactless module switch that can monitor capacitor attenuation using the control logic of the present invention, and a comparative scheme that uses the difference between the fundamental current before and after conventional switching for capacity estimation.

[0061] During testing, two sets of devices were connected to the same low-voltage compensation bus, with the compensation target being a simulated load in the steelmaking workshop's power distribution circuit. The load side included frequency converters and rectifiers to simulate harmonic and reactive power fluctuations. Each set ran continuously for 15 days, and monitoring results were recorded after multiple switching operations of the target capacitor. During the test, grid voltage fluctuations remained within ±6% of the rated value, and the total harmonic distortion rate of the current was approximately 6.8%–9.5%. The target capacitor's nominal capacity was 30 kvar, and after offline retesting, the corresponding actual capacity was approximately 27.9 kvar. This measured value was used as the test reference value. The statistical results are shown in the table below. Capacitor offline retest capacitance / kvar 27.9 27.9 Online monitoring average value / kvar 29.4 28.2 Maximum deviation per single monitoring session / kvar 2.3 0.8 Multiple monitoring of fluctuation range / kvar 28.6～30.2 27.6～28.4 Corresponding capacity decay identification results No attenuation alarm triggered Determined as mild attenuation Number of misjudgments during continuous operation 2 times 0 times The test results show that, under conditions of harmonic disturbances and continuous load fluctuations, the conventional monitoring method based on the difference between the fundamental current before and after switching is significantly affected by switching transients and changes in line background. Its online monitoring results are generally high and exhibit significant dispersion, especially under some continuous switching conditions, where there is a noticeable deviation between the monitored values ​​and the actual capacitor capacity. In contrast, this invention uses the thyristor switching moment as an event reference to synchronously analyze the response segment corresponding to the target capacitor, and further separates the independent fundamental reactive power response corresponding to this switching in the changing response sequence. The resulting monitoring results are closer to the offline retest values. In the continuous operation record, the fluctuation amplitude of each sampling result is relatively small, and it can still maintain relatively stable capacity identification results even when the load fluctuation is significant.

[0062] In addition, after artificially reducing the capacitance of one set of capacitors in the later stage of the test, the present invention can continuously identify the decrease in output capability in multiple subsequent switching cycles and correspondingly extend the lock-up period for that branch to participate in compensation again; while the comparative solution failed to stably identify the change in some cycles.

[0063] The above test results show that the high-power contactless module switch for monitoring capacitor attenuation proposed in this invention can identify the actual reactive power output capability of the target capacitor online during dynamic reactive power compensation operation without adding additional dedicated testing equipment. It also maintains good monitoring stability under harmonic and load fluctuation conditions, and can provide effective data support for capacitor operation and maintenance and compensation branch control.

[0064] It should be understood that the above test data are the results of the applicant's embodiments under existing prototypes and typical working conditions, and are only used to illustrate the feasibility and practical application effect of the technical solution of the present invention, and do not constitute a limitation on the scope of protection of the present invention.

[0065] The above provides a detailed description of a high-power contactless module switch capable of monitoring capacitor attenuation, as provided in this application. Those skilled in the art will recognize that the algorithm steps of the various examples described in conjunction with the embodiments disclosed in this invention can be implemented using electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention. The above description of the embodiments is merely for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A high-power contactless module switch capable of monitoring capacitor attenuation; The system includes a thyristor switching module, a current sampling module, and a control module. The thyristor switching module is used for contactless switching of capacitor banks. The control module is characterized in that it performs the following processing steps: During the operation of the target capacitor, the line current sampling signal of the current sampling module is acquired, and the current characteristic quantity reflecting the change of the line fundamental reactive power is extracted. When the target capacitor is switched, the corresponding switching trigger time is used as the event reference time to construct a response analysis window for the current characteristic quantity that is synchronized with the switching event; and the change response sequence is calculated based on the current characteristic quantity corresponding to the continuous power frequency cycle within the response analysis window. Based on the temporal correlation between the change response sequence and the event reference time, the event response component caused by the switching of the target capacitor in the change response sequence is identified and separated from the dynamic change component of the line background to obtain the independent fundamental reactive power response quantity corresponding to the target capacitor. The actual reactive power output capacity of the target capacitor is calculated based on the independent fundamental reactive power response, and compared with the rated output capacity to obtain the attenuation state parameters of the target capacitor. The switching control of the target capacitor in reactive power compensation is adjusted based on the attenuation state parameters.

2. A high-power contactless module switch capable of monitoring capacitor attenuation according to claim 1, characterized in that: The process by which the control module extracts current characteristic quantities reflecting the fundamental reactive power variation of the line includes: Synchronous phase locking is performed on the line current sampling signal to obtain the synchronous phase angle corresponding to the fundamental voltage of the power grid. The synchronous phase locking uses a digital phase-locked loop to track the phase of the fundamental voltage in real time. Based on the synchronous phase angle, the line current sampling signal is transformed to a synchronous rotating coordinate system to obtain the direct-axis current component and the quadrature-axis current component; The quadrature-axis current component is used as the fundamental reactive current characteristic quantity corresponding to the target capacitor.

3. A high-power contactless module switch capable of monitoring capacitor attenuation according to claim 1, characterized in that: The response analysis window for constructing the current characteristic quantity in sync with the switching event includes: Acquire the trigger signal of the thyristor corresponding to the target capacitor and record the thyristor conduction time. Take the first zero-crossing point of the line voltage after the conduction time as the response start position. The fundamental reactive current characteristic quantity is continuously segmented according to the power frequency cycle, and the response start position is used as the segmentation start point to extract the whole cycle of each power frequency cycle. A series of consecutive complete power frequency cycles before the response start position are selected as the pre-switching response segment, and a series of consecutive complete power frequency cycles after the response start position are selected as the post-switching response segment. The pre-switching response segment and the post-switching response segment are spliced ​​together to form a response analysis window that is synchronized with the target capacitor switching event.

4. A high-power contactless module switch capable of monitoring capacitor attenuation according to claim 1, characterized in that: The process by which the control module calculates the changing response sequence based on the current characteristic quantities corresponding to continuous power frequency cycles within the response analysis window includes: The response analysis window is divided into multiple continuous complete power frequency cycles, and the fundamental reactive current characteristic quantity corresponding to each power frequency cycle is extracted respectively. ,in, This indicates the power frequency cycle number based on the starting position of the response; The center period is the power frequency period at which the target capacitor is switched on / off. The fundamental reactive current characteristic quantities corresponding to multiple power frequency cycles before and after the center cycle are obtained respectively; for any power frequency cycle Calculate the corresponding change response value using the following formula: in, Indicates the first The change response value corresponding to each power frequency cycle; Indicates the first The fundamental reactive current characteristic quantity corresponding to each power frequency cycle; and They represent the first The fundamental reactive current characteristic quantities corresponding to the first and last power frequency cycles. Arrange the change response values ​​in order of power frequency cycle. This forms the change response sequence.

5. A high-power contactless module switch capable of monitoring capacitor attenuation according to claim 1, characterized in that: The time-series correlation is centered on the power frequency cycle corresponding to the event reference time. It reads the change response values ​​corresponding to the same number of power frequency cycles before and after the event, and performs a difference operation on two symmetrically positioned change response values ​​to obtain... ,in, Indicates the first The change response value corresponding to each power frequency cycle; This indicates the power frequency cycle number corresponding to the reference time of the event; This represents the offset of the power frequency cycle relative to the reference time of the event; Indicates the first The timing difference value corresponding to the offset position of each power frequency cycle; The control module determines the power frequency cycle segment where the sum of the absolute values ​​of multiple consecutive timing differences is the smallest as the event response segment of the target capacitor.

6. A high-power contactless module switch for monitoring capacitor attenuation according to claim 5, characterized in that: The process by which the control module identifies the event response component in the changing response sequence caused by the switching of the target capacitor includes: The background drift baseline is established by taking the change response value corresponding to the first power frequency cycle and the change response value corresponding to the last power frequency cycle of the event response segment, and the background drift baseline is subtracted from the change response value corresponding to each power frequency cycle in the event response segment to obtain the correction response value corresponding to each power frequency cycle. The corrected response values ​​are weighted and accumulated according to the power frequency cycle offset relative to the event reference time to obtain the event response component corresponding to the target capacitor. The calculation formula is: in, This represents the event response component corresponding to the target capacitor; Indicates the first event within the event response segment The change response value corresponding to each power frequency cycle; Indicates the first Background drift baseline value corresponding to each power frequency cycle; Indicates the first Weighting coefficients corresponding to each power frequency cycle; Indicates the power frequency cycle number within the event response segment; The weighting coefficient represents the number of power frequency cycles contained in the event response segment. It decreases as the distance between the power frequency cycle and the reference time of the event increases.

7. A high-power contactless module switch for monitoring capacitor attenuation according to claim 6, characterized in that: The control module separates the event response component from the dynamic change component of the line background to obtain the independent fundamental reactive power response quantity corresponding to the target capacitor. This includes: starting from the power frequency cycle corresponding to the event reference time, sequentially reading the correction response value corresponding to each power frequency cycle along the event response segment, determining the position where the product of the correction response values ​​corresponding to two adjacent power frequency cycles is less than zero for the first time as the event response boundary, and extracting the correction response value corresponding to the event reference time and the event response boundary as the independent fundamental reactive power response quantity of the target capacitor.

8. A high-power contactless module switch for monitoring capacitor attenuation according to claim 1, characterized in that: The calculation of the actual reactive power output capacity of the target capacitor based on the independent fundamental reactive power response, and the comparison with the rated output capacity, to obtain the attenuation state parameters of the target capacitor, includes: Record the cumulative number of switching operations for the target capacitor. The rated output capacity of the target capacitor is corrected based on the cumulative number of switching operations; the independent fundamental reactive power response is compared with the corrected rated output capacity to obtain the attenuation state parameters of the target capacitor. The expression is: in, This represents the independent fundamental reactive response quantity corresponding to the target capacitor; This indicates the rated reactive power output capacity of the target capacitor; Indicates the cumulative number of times the target capacitor has been switched on and off; The correction factor for the rated output capacity corresponding to a single switching operation is calculated using the following formula: in, Indicates the cumulative completion of the target capacitor The baseline reactive power output capability after the second switching; This indicates the cumulative number of switching operations when the target capacitor corresponds to the aforementioned baseline reactive power output capacity.

9. A high-power contactless module switch capable of monitoring capacitor attenuation according to claim 1, characterized in that: The control module adjusts the switching control of the target capacitor participating in reactive power compensation through hierarchical constraint processing, including: After the target capacitor is taken out of operation, the control module calculates the number of switching lock-in cycles corresponding to the target capacitor based on the attenuation state parameters. The target capacitor is prohibited from being put back into operation within the specified number of switching lockout cycles; the specified number of switching lockout cycles The calculation formula is: in, This indicates the number of switching lock-up cycles corresponding to the target capacitor; This represents the response bias weighting coefficient; This represents the cumulative weighting coefficient for the switching action; Indicates the target capacitor number The independent fundamental reactive power response corresponding to each monitoring step; Indicates the target capacitor number The rated reactive power output capacity corresponding to the next monitoring; Indicates the cumulative number of times the target capacitor has been switched on and off; This indicates the number of monitoring sessions included in the statistical calculations; After the switching lockout period ends, the control module allows the target capacitor to re-participate in the reactive power compensation switching control.

10. A high-power contactless module switch capable of monitoring capacitor attenuation according to claim 1, characterized in that: After the target capacitor is taken out of operation, the control module continuously collects the voltage across the target capacitor. and the voltage connected to the bus When satisfied When this occurs, the target capacitor is allowed to enter the next switching monitoring cycle; wherein, This represents the allowable voltage difference coefficient, and ; If the above conditions are not met, the control module keeps the target capacitor in the exit state and suspends the update of the decay state parameters of the target capacitor.

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