A method for analyzing parameter optimization of a capacitor type reactor bank

Abstract

The application belongs to the technical field of parameter optimization of electric reactors, and particularly discloses a parameter optimization analysis method for a capacitor type electric reactor set, which calculates the phase difference of fundamental wave voltage and current and the total harmonic distortion rate in real time after the capacitor type electric reactor set is put into operation, and synchronously observes whether the phase difference and the total harmonic distortion rate deteriorate with the current amplitude increment as the trigger condition, so as to determine whether the electric reactance rate drifts, which can actively identify the electric reactance rate drift caused by the continuous increase of load, overcome the defect that the prior art cannot perceive such drift, and simultaneously determines the inductance adjustment direction according to whether the winding temperature is out of limit after determining that the electric reactance rate drifts, and outputs the adjustment instruction with the minimum inductance adjustment unit as the fixed step, so that the target inductance value is calculated without relying on a mathematical model, the optimal inductance value is gradually approached through successive adjustment, and the adjustment deviation caused by the system parameter uncertainty is effectively eliminated.

Description

Technical Field

[0001] This invention belongs to the field of reactor parameter optimization technology, and specifically discloses a method for optimizing and analyzing the parameters of a capacitive reactor group. Background Technology

[0002] Capacitive reactor banks are important devices for suppressing harmonics in power systems, and the key to their harmonic suppression effect lies in their reactance. When the reactance is at the design value, the LC series branch forms a quasi-resonance at a specific harmonic frequency point, effectively absorbing harmonics.

[0003] However, after the capacitive reactor bank is put into operation, the continuous increase in load will lead to the saturation of the reactor core and the temperature rise of the winding. At the same time, the aging of the capacitor dielectric will also cause the capacitance to decay. These factors can easily cause the reactance rate to drift. Since the continuous increase in load is a common operating condition, the reactance rate caused by it has the characteristics of slow accumulation and difficulty in detection. If it cannot be identified and optimized in time, the harmonic suppression effect will be in a state of long-term deterioration.

[0004] To solve the above problems, it is necessary to optimize the parameters of the capacitive reactor bank to maintain a stable reactance rate.

[0005] To address the reactance drift problem, existing parameter optimization schemes mostly adopt a calculation-driven approach, that is, calculating the target inductance value through a mathematical model to adjust the reactor to the correct position in one go. However, in actual operation, there are uncertainties in the system parameters, which leads to a deviation between the calculated target value and the actual optimal value, and the adjustment result is not the optimal match.

[0006] At the same time, existing parameter optimization schemes lack verification of the adjustment effect, cannot detect deviations or correct them, and the adjusted reactance rate is still prone to deviating from the optimal state. Summary of the Invention

[0007] To solve the above-mentioned technical problems, or at least partially solve them, this invention provides a method for optimizing and analyzing the parameters of a capacitive reactor bank. This method actively identifies reactance drift and uses a closed-loop verification approach to gradually approach the optimal state.

[0008] The objective of this invention can be achieved through the following technical solution: This invention proposes a parameter optimization analysis method for a capacitive reactor group, which includes the following steps: collecting the operating parameters of the capacitive reactor group after it is put into operation, including the reactor branch current, capacitor terminal voltage and reactor winding temperature, and using the collected operating parameters to calculate the fundamental voltage-current phase difference and total harmonic distortion rate.

[0009] Using the continuous increase in current amplitude as the trigger condition, observe whether the phase difference between the fundamental voltage and current and the total harmonic distortion rate deteriorate synchronously, thereby determining whether the reactance has drifted.

[0010] When drift is detected, the direction of inductance adjustment is determined based on whether the winding temperature exceeds the limit, and the adjustment command is output with the minimum inductance adjustment unit as the adjustment step size.

[0011] After a stabilization waiting window, the fundamental voltage-current phase difference and total harmonic distortion rate are recalculated and compared with the values ​​before adjustment. Based on the comparison results before and after adjustment, it is determined whether the adjustment direction is correct.

[0012] When the adjustment direction is correct, the fixed step size adjustment is repeated in the correct direction until the termination condition is met. Otherwise, the current adjustment is canceled and the same fixed step size adjustment command is output in the opposite direction for verification.

[0013] Combining all the above technical solutions, the positive effects of this invention are as follows: 1. This invention calculates the fundamental voltage-current phase difference and total harmonic distortion rate in real time after the capacitive reactor group is put into operation, and uses the continuous increase of the current amplitude as the trigger condition to synchronously observe whether the phase difference and total harmonic distortion rate deteriorate along with it, thereby judging whether the reactance has drifted. It can actively identify the reactance drift caused by the continuous increase of load, which is beneficial to avoid the harmonic suppression effect being in a state of long-term deterioration.

[0014] 2. After determining that the reactance has drifted, the present invention determines the inductance adjustment direction based on whether the winding temperature exceeds the limit, and outputs the adjustment command with the minimum inductance adjustment unit as the fixed step size. It does not need to rely on mathematical models to calculate the target inductance value. By adjusting successively, it gradually approaches the optimal inductance value, effectively eliminating the adjustment deviation caused by the uncertainty of system parameters and improving the adaptability of parameter optimization.

[0015] 3. This invention verifies the adjustment direction by comparing the phase difference and distortion rate after each adjustment, and performs undo and reverse correction operations when the direction is incorrect, ensuring that each adjustment is in the correct direction of reactance recovery. This overcomes the shortcomings of existing technologies that lack verification and correction, thereby ensuring the convergence of the adjustment process and the accuracy of the adjustment results. Attached Figure Description

[0016] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0017] Figure 1 This is a diagram illustrating the method steps in this invention;

[0018] Figure 2 This is a flowchart illustrating the implementation of the termination condition determination in this invention;

[0019] Figure 3 This is a flowchart illustrating the implementation of reverse regulation in this invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Capacitive reactor banks typically consist of series reactors and parallel capacitors, connected in parallel to the bus or feeder of the power system. During operation, the capacitor bank provides capacitive reactive power to compensate for the inductive reactive power of the system. At the same time, the series reactors and capacitors together form an LC filter branch. In this process, the reactance rate determines the resonance characteristics of the LC branch at specific harmonic frequencies.

[0022] At the factory, capacitive reactor banks are configured with a nominal reactance rate based on the anticipated background harmonics of the power grid. When the reactance rate equals the design value, the LC branch exhibits a quasi-resonant state at the target harmonic frequency, providing a low-impedance path for harmonic currents and effectively absorbing the harmonic. However, in actual operation, the reactance rate is not constant. As the power system load continues to increase, the current amplitude flowing through the reactor branch rises accordingly, causing the core flux density to enter the saturation region and the inductance to decrease significantly. At the same time, the copper and iron losses caused by the increased current raise the winding temperature, further altering the core permeability and exacerbating reactance rate drift.

[0023] Because of frequent periodic load fluctuations, each load increase can trigger varying degrees of reactance drift, which slowly intensifies with current accumulation, exhibiting both insidious and persistent characteristics. If not identified and compensated for in a timely manner, harmonic suppression will remain degraded over a long period, potentially even inducing harmonic amplification and equipment overheating.

[0024] To address the above problems, the present invention proposes the following technical solutions: Figure 1 As shown, the present invention proposes a parameter optimization analysis method for a capacitive reactor group, including the following steps: S1, collecting the operating parameters of the capacitive reactor group after it is put into operation, including the reactor branch current, capacitor terminal voltage and reactor winding temperature, and using the collected operating parameters to calculate the fundamental voltage-current phase difference and total harmonic distortion rate.

[0025] To optimize reactance drift, the primary condition is accurate assessment of the drift itself. This accurate assessment relies on obtaining a characterization of the reactance drift. The direct characterization of reactance drift is the deviation of the resonant characteristics of the reactor-capacitor series branch from the design value. This deviation can be reflected by changes in the fundamental voltage-current phase difference and the total harmonic distortion (THD) of the branch. Therefore, it is necessary to collect raw parameters capable of calculating these two characteristic quantities: reactor branch current and capacitor terminal voltage.

[0026] Specifically, the acquisition process is as follows: S11, the instantaneous value of the branch current is continuously acquired using the current transformer installed in the reactor branch, which is used to calculate the amplitude and phase of the fundamental current, so as to obtain the trend of current amplitude change and voltage-current phase difference.

[0027] S12. Use a voltage divider installed at the capacitor terminal to collect the instantaneous value of the capacitor terminal voltage. This voltage is the direct basis for calculating the fundamental voltage-current phase difference and total harmonic distortion rate.

[0028] S13. Considering that the winding temperature will affect the actual inductance value of the reactor, and thus cause the reactance rate to drift, the winding temperature also needs to be monitored synchronously while collecting electrical parameters.

[0029] Specifically, temperature sensors are pre-embedded at different axial heights of the reactor winding to obtain the winding temperature distribution. Since the reactor winding is not a uniform heat source, the heat dissipation conditions vary at different heights. By collecting the temperature at multiple height points, it is possible to accurately determine whether there is a temperature rise trend in the winding, thus providing a basis for subsequent judgment on whether the reactance has drifted.

[0030] S14. All signals are filtered and synchronously sampled to form a time-aligned sampling sequence.

[0031] After data acquisition, the next step is to calculate the two characteristic quantities: the fundamental voltage-current phase difference and the total harmonic distortion rate. The specific calculation process is as follows: extract the instantaneous values ​​of the branch current and the capacitor terminal voltage from the sampling sequence. Since the actual power grid signal contains abundant harmonic components, directly measuring the phase difference will be subject to harmonic interference; therefore, it is necessary to extract the fundamental component first.

[0032] In one example, the zero-crossing detection method is used: the time when the capacitor terminal voltage and the branch current waveform cross the zero point (from negative to positive or from positive to negative) are detected respectively, the time difference between the two zero-crossing points is calculated, and then multiplied by the angular frequency to obtain the fundamental voltage-current phase difference.

[0033] In another example, a digital phase-locked loop method is used: the phase angle of the fundamental voltage component is locked in real time by a closed-loop tracking loop, while the phase angle of the fundamental current component is measured. The difference between the two is the fundamental voltage-current phase difference.

[0034] The phase difference between the fundamental voltage and current directly reflects the impedance characteristics of the reactor-capacitor series branch at the fundamental frequency: when the phase difference is close to zero, the branch is in a quasi-resonant state and the reactance is close to the design value; when the phase difference deviates from zero, it indicates that the reactance has drifted, and the greater the deviation, the more serious the drift.

[0035] Simultaneously, a Fast Fourier Transform (FFT) is performed on the capacitor terminal voltage to extract the amplitudes from the fundamental frequency to the preset highest harmonic. The preset highest harmonic refers to an analysis upper limit pre-set based on the system's main harmonic background, such as the 5th, 7th, and 11th harmonics. This typically covers harmonic orders that significantly impact power quality; harmonic components outside this range have negligible amplitudes. The total harmonic distortion rate of the capacitor terminal voltage is obtained by taking the square root of the sum of the squares of the harmonic amplitudes and comparing it to the fundamental frequency amplitude. This distortion rate characterizes the degree of harmonic amplification after branch detuning and, together with the phase difference, serves as a basis for judging reactance drift.

[0036] S2. Using the continuous increase of current amplitude as the trigger condition, observe whether the phase difference between the fundamental voltage and current and the total harmonic distortion rate deteriorate synchronously, thereby determining whether the reactance rate has drifted.

[0037] After calculating the fundamental voltage-current phase difference and total harmonic distortion rate, these two characteristic quantities can be used to determine whether the reactance has drifted. The specific implementation steps are as follows: S21. Since the continuous increase of the current amplitude is a precursor physical quantity of reactance drift, the current amplitude of the reactor branch calculated in the current detection cycle is compared with that in the previous detection cycle. The detection cycle refers to the time interval between two adjacent characteristic quantity calculations, which is usually one power frequency cycle. If the current current amplitude is greater than that in the previous cycle and remains so for three consecutive detection cycles, it indicates that the load is in a state of continuous increase, which serves as the trigger condition for the continuous increase of the current amplitude.

[0038] S22. Within the time interval when the triggering condition is met, synchronously observe the fundamental voltage-current phase difference and total harmonic distortion rate.

[0039] If the absolute value of the phase difference increases monotonically, and the total harmonic distortion rate increases monotonically while the dominant harmonic order remains unchanged, it indicates that the resonant characteristics of the reactor-capacitor branch are gradually deviating from the design value, and the reactance rate is continuously deteriorating. The dominant harmonic order is the harmonic order with the largest amplitude among all harmonics in the total harmonic distortion rate of the capacitor terminal voltage. At this time, it is initially judged that the reactance rate is suspected to be drifting.

[0040] S23. After the initial judgment is established, considering that transient impacts or instantaneous load fluctuations may lead to misjudgments, it is necessary to further verify the continuity of the load increase and the stability of the drift. Therefore, continue to monitor the current amplitude of the reactor branch in the next detection cycle: S231. If the current amplitude in the next cycle is still greater than or equal to the amplitude at the beginning of the load increase, it indicates that the load increase has not been interrupted and the driving force of the reactance drift still exists. At the same time, the fundamental voltage-current phase difference and the total harmonic distortion rate continue to show the same monotonically increasing characteristics, which indicates that the drift direction is consistent and has not reversed. At this time, it can be confirmed that the reactance has drifted, and optimization is directly triggered.

[0041] S232. If the current amplitude in the next cycle does not show a continuous increase, but the fundamental voltage-current phase difference and distortion rate still show a monotonically increasing characteristic, it means that the drift may be caused by other factors. The most common one is the inductance drift caused by the increase in reactor winding temperature. To confirm whether it is caused by temperature, further check the reactor winding temperature.

[0042] Because temperature sensors are pre-embedded at different axial heights of the reactor winding, temperature values ​​at multiple height points can be obtained. Usually, the highest temperature value at each height is taken as the current winding temperature.

[0043] If, within the same time period during which both the phase difference and distortion rate increase monotonically, the winding temperature rises continuously (meaning the maximum winding temperature in each detection cycle is higher than the maximum winding temperature in the previous detection cycle), then the reactance rate is determined to have drifted. This indicates that the temperature increase is the direct cause of inductance drift, which in turn leads to reactance rate drift. Therefore, it is also determined to be reactance rate drift and optimization is triggered. This is because temperature-induced reactance rate drift will also cause the reactance rate to deviate from the design value. If optimization is not performed in time, the harmonic suppression effect will continue to deteriorate. If the temperature does not rise synchronously, it is determined to be due to other uncertain reasons, and optimization is not triggered to avoid malfunctions.

[0044] The above-mentioned judgment on reactance drift is based on the continuous increase of current amplitude as the trigger condition and the synchronous deterioration of fundamental voltage-current phase difference and distortion rate as the observation characteristics. The final judgment is made after subsequent periodic verification or temperature-assisted confirmation. This progressive judgment can effectively eliminate transient disturbances and measurement noise, and ensure that only real drift triggers optimization.

[0045] S3. When drift is detected, the inductance adjustment direction is determined based on whether the winding temperature exceeds the limit, and the adjustment command is output with the minimum inductance adjustment unit as the adjustment step size.

[0046] Once drift is detected, parameter optimization can be performed. This invention uses inductance adjustment to restore reactance, because the main cause of reactance drift is the decrease in inductance due to core saturation or temperature rise. Since the reactor in this invention is an adjustable reactor, its inductance value can be adjusted in steps during operation. Therefore, the drift can be directly compensated by actively adjusting the inductance value, bringing it back to near the design value.

[0047] Inductor adjustment first requires determining the adjustment direction, as an incorrect adjustment direction will exacerbate drift and further worsen the harmonic suppression effect. Specifically, the current reactor winding temperature is monitored, and the highest temperature at each height is used as the basis for judgment. If the highest temperature is below the safety limit, it indicates that the temperature rise is still within a controllable range. At this time, the drift is mainly caused by core saturation, and the inductance should be increased to compensate for the decrease in inductance caused by saturation. If the highest temperature reaches or exceeds the safety limit, it indicates that overheating has become the main problem. Continuing to increase the inductance will further aggravate iron losses and temperature rise. Therefore, the inductance should be reduced to reduce heat generation and prioritize equipment safety.

[0048] The above safety limits can be set according to the maximum allowable operating temperature corresponding to the insulation heat resistance class of the reactor. Usually, a certain percentage of the maximum operating temperature, such as 90%, is taken as the safety limit.

[0049] After determining the adjustment direction, it is also necessary to determine the adjustment step size. Specifically, the minimum adjustment unit of the inductance of the reactor actuator is obtained from the calibration test before the reactor leaves the factory and is used as the adjustment step size.

[0050] S4. After a stable waiting window, recalculate the fundamental voltage-current phase difference and total harmonic distortion rate, and compare them with the values ​​before adjustment. Based on the comparison results before and after adjustment, determine whether the adjustment direction is correct.

[0051] After the S3 adjustment command is output, the inductance value of the reactor changes. However, this change in inductance will cause transient oscillations in the branch current. Accurate measurement of the adjusted electrical parameters can only be performed after the oscillations have decayed to a steady state. Therefore, the phase difference and distortion rate need to be recalculated after a stabilization waiting window to ensure the reliability of the comparison results and avoid measurement errors introduced by the transient process.

[0052] As a preferred embodiment of the present invention, the process of determining the stable waiting window is as follows: when the capacitive reactor bank is put into operation for the first time, a self-test is performed: the controller outputs a test adjustment command with a preset direction and a size equal to the minimum adjustment unit of inductance. This direction is used to excite the reactor to generate a standard step change in inductance. For example, the default is to increase the inductance direction. At the same time, high-speed sampling is started to collect the complete transient waveform of the reactor branch current from the start of adjustment to the recovery to the new steady state. The envelope of the transient component is extracted from the waveform to quantify the decay rate of the current oscillation.

[0053] The time required for the envelope to decay from its peak value to a set percentage is measured. The set percentage refers to a certain percentage of the envelope peak value decaying back to its initial peak value. This percentage can be set according to the requirements for steady-state error. The higher the requirement, the smaller the set percentage should be. Preferably, the peak value decays to 10% to 30%. This time is recorded as the transient decay time constant of the reactor magnetic circuit under the current operating condition, which reflects how quickly the current recovers to a steady state after inductor adjustment.

[0054] However, relying solely on the time constant as a waiting window may still leave behind incompletely decayed oscillating components, affecting the accuracy of subsequent measurements. Therefore, the transient decay time constant of the reactor's magnetic circuit is multiplied by a safety factor to determine the duration of the stabilization waiting window. This ensures the transient process completely subsides, thereby guaranteeing the reliability of subsequent phase difference and distortion rate measurements. The safety factor is a multiple greater than 1, such as 3.

[0055] After the system stabilizes, since the adjustment direction determined in step S3 is based on the winding temperature, this direction may deviate in actual operation, so it is necessary to verify its correctness. Since the phase difference and distortion rate are recorded before and after adjustment, the adjustment effect can be directly reflected by comparing the changes in these two characteristic quantities, thus determining whether the adjustment direction is correct. The specific judgment process is as follows: After the stabilization waiting window ends, the absolute value of the fundamental voltage-current phase difference and the total harmonic distortion rate are recalculated and compared with the corresponding values ​​before adjustment.

[0056] If the following conditions are met simultaneously, the direction of this adjustment is determined to be correct, and the current inductance value is used as the new reference for the next adjustment in the same direction. Otherwise, the direction is determined to be incorrect: a) Basic conditions: The absolute value of the phase difference between the fundamental voltage and current and the total harmonic distortion rate after adjustment are both less than the corresponding values ​​before adjustment. The decrease in the absolute value of the phase difference means that the branch is closer to the resonance state, and the decrease in the distortion rate means that the harmonic amplification is weakened. The improvement of both is the basic premise of the correct direction.

[0057] b) Calculate the decrease in the absolute value of the phase difference and the decrease in the total harmonic distortion rate, and divide both by the values ​​before adjustment to obtain the dimensionless relative decrease rate of phase difference and the relative decrease rate of distortion rate.

[0058] Establish a coordinate system with the relative reduction rate of phase difference on the horizontal axis and the relative decrease rate of distortion on the vertical axis. The relative reduction rate and relative decrease rate obtained after adjustment constitute a coordinate point. The line segment from the origin to this point is a two-dimensional vector.

[0059] The angle between the two-dimensional vector and the positive direction of the horizontal axis reflects the relative improvement ratio of the two indicators: the larger the angle, the higher the ratio of the decrease in distortion rate to the decrease in phase difference.

[0060] The smaller the angle, the higher the proportion of the phase difference reduction relative to the distortion rate reduction.

[0061] This imbalance can lead to adjustments that are effective but not coordinated, and may result in a one-sided pursuit of one indicator while ignoring another.

[0062] When the included angle is within the range formed by the upper and lower limits of the synergistic angle, such as 40° to 60°, it indicates that the improvement ratio of the two indicators is coordinated, and there is no situation where one indicator is over-improved while the other indicator is under-improved, so that the adjustment effect is comprehensive and balanced. The upper and lower limits of the synergistic angle mentioned above are set based on 45°. When the included angle is exactly 45°, the relative reduction rate of the absolute value of the phase difference is equal to the relative reduction rate of the total harmonic distortion rate, and the improvement ratio of the two indicators is completely consistent, reaching a coordinated state.

[0063] By double-checking the above conditions a) and b), we can ensure that each adjustment of direction not only brings about comprehensive improvement, but also the improvement is balanced, thus providing a reliable directional benchmark for subsequent iterations to approach the optimal state.

[0064] S5. When the adjustment direction is correct, repeat the fixed step size adjustment in the correct direction until the termination condition is met. Otherwise, cancel the current adjustment and output the same step size adjustment command in the opposite direction to verify again.

[0065] S51. When the adjustment direction is correct, it indicates that the current adjustment direction can improve the reactance. Therefore, the adjustment can continue in this direction to gradually approach the optimal inductance value. To avoid over-adjustment leading to repeated effects or equipment fatigue, a termination condition should be set, and the adjustment should be stopped in time when the improvement effect is no longer significant.

[0066] See Figure 2 As shown, in a preferred embodiment, the specific determination process of the termination condition is as follows: S511, after confirming that the adjustment direction is correct, the fixed step size adjustment is repeatedly performed along the current direction, and the improvement amount brought by the adjustment is calculated after each adjustment.

[0067] Before calculation, first check whether the absolute value of the fundamental voltage-current phase difference and the total harmonic distortion rate have decreased compared with before adjustment. If either indicator has not decreased, the adjustment is deemed invalid, and the adjustment is terminated and the result of the adjustment is rolled back.

[0068] The improvement is calculated when both indicators decrease: the improvement is defined as the square root of the product of the relative reduction rate of the absolute value of the phase difference and the relative reduction rate of the total harmonic distortion (THD), i.e., the geometric mean. Here, the relative reduction rate refers to the proportion of the decrease in the absolute value of the phase difference to its original value before adjustment, and the relative reduction rate refers to the proportion of the decrease in the distortion rate to its original value before adjustment; both are dimensionless. This calculation method comprehensively reflects the degree of synchronous improvement of the two indicators. The improvement is positive only when both indicators improve; if only one indicator improves while the other remains unchanged, the product is zero, and the improvement is zero. This avoids misjudging an effective improvement when one indicator improves while the other remains unchanged.

[0069] S512. Compare the improvement amount of this adjustment with the improvement amount of the previous adjustment: If the improvement amount of this adjustment is less than the improvement amount of the previous adjustment or the improvement amount of this adjustment is zero, it indicates that the improvement effect is no longer increasing or there is no improvement. At this time, the adjustment is terminated. When the improvement amount is zero, the adjustment is rolled back and the inductance value of the reactor is restored to the state before the start of this adjustment. When the improvement amount of this adjustment is less than the improvement amount of the previous adjustment, the adjustment is retained and the inductance value of the reactor is maintained at the new value after adjustment.

[0070] If the improvement amount in this instance is greater than zero and not less than the previous improvement amount, then the next adjustment will continue until the improvement amount is zero or less than the previous improvement amount, at which point the adjustment will terminate.

[0071] See Figure 3 As shown in S52, when the adjustment direction is incorrect, it means that the currently selected adjustment direction cannot improve the reactance rate, or may even worsen the situation. Therefore, it is necessary to reverse the adjustment to explore the correct adjustment direction. The specific process is as follows: S521, when the adjustment direction is incorrect, first cancel the current adjustment command and restore the reactor inductance value to the state before adjustment, that is, roll back the invalid adjustment to avoid the continuous impact of the incorrect direction.

[0072] S522: Output adjustment commands with the same step size in the opposite direction, and recalculate the absolute value of phase difference and total harmonic distortion rate after the stabilization waiting window ends.

[0073] S523. If the absolute value of the phase difference and the total harmonic distortion rate after adjustment are both less than before adjustment, and the angle between the vector formed by the relative reduction rate of the absolute value of the phase difference and the relative decrease rate of the total harmonic distortion rate and the positive direction of the coordinate axis is within the range formed by the upper limit of the cooperative angle and the lower limit of the cooperative angle, then the direction is confirmed to be correct, and the fixed step size adjustment is repeated along the current direction.

[0074] If the calculation result after reverse adjustment does not meet the correct direction condition, given that the original step size may be too large in this direction, leading to overshoot or abnormal response, the adjustment step size is reduced to half of the original step size to verify whether the correctness of this direction is masked by the excessive step size; the adjustment command is output again in the opposite direction, and the phase difference and distortion rate are recalculated after the stabilization waiting window.

[0075] If the adjustment after reducing the step size meets the above-mentioned correct direction condition, it means that the original step size was too large, causing the adjustment to exceed the optimal range. At this time, the fixed step size adjustment is repeated along the current direction by reducing the step size to gradually approach the optimal inductance value until the termination condition is met.

[0076] If two consecutive reverse adjustments of different timing lengths fail to meet the correct direction condition, it indicates that the reactance rate cannot be effectively improved by inductor adjustment under the current operating conditions. This may be due to hardware failure or other abnormalities. In this case, the optimization will be terminated and an alarm signal will be output.

[0077] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0078] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in 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 application.

[0079] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0080] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0081] Finally, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for optimizing and analyzing parameters of a capacitive reactor bank, characterized in that, include: The operating parameters of the capacitor bank after commissioning are collected, including the reactor branch current, capacitor terminal voltage and reactor winding temperature. The fundamental voltage-current phase difference and total harmonic distortion are calculated using the collected operating parameters. Using the continuous increase in current amplitude as the trigger condition, observe whether the fundamental voltage-current phase difference and total harmonic distortion rate deteriorate synchronously, thereby determining whether the reactance rate has drifted. When drift is detected, the direction of inductance adjustment is determined based on whether the winding temperature exceeds the limit, and the adjustment command is output with the minimum inductance adjustment unit as the adjustment step size. After a stabilization waiting window, the fundamental voltage-current phase difference and total harmonic distortion rate are recalculated and compared with the values ​​before adjustment. Based on the comparison results before and after adjustment, it is determined whether the adjustment direction is correct. When the adjustment direction is correct, the fixed step size adjustment is repeated in the correct direction until the termination condition is met. Otherwise, the current adjustment is canceled and the same step size adjustment command is output in the opposite direction for verification.

2. The method for optimizing and analyzing parameters of a capacitive reactor bank as described in claim 1, characterized in that: The process of collecting the operating parameters of the capacitive reactor group after it is put into operation is as follows: The instantaneous value of the branch current is continuously obtained using a current transformer installed in the reactor branch; The instantaneous value of the capacitor terminal voltage is collected using a voltage divider installed at the capacitor terminal. Temperature sensors are pre-embedded at different axial heights of the reactor winding to obtain the winding temperature; All signals are filtered and synchronously sampled to form a time-aligned sampling sequence.

3. The method for optimizing and analyzing parameters of a capacitive reactor bank as described in claim 2, characterized in that: The calculation of the fundamental voltage-current phase difference and total harmonic distortion includes the following: The instantaneous values ​​of branch current and capacitor terminal voltage are extracted from the sampling sequence. The fundamental component is extracted using zero-crossing detection or digital phase-locked loop. The fundamental voltage-current phase difference between the capacitor terminal voltage and the branch current is calculated.

4. The method for optimizing and analyzing parameters of a capacitive reactor bank as described in claim 2, characterized in that: The total harmonic distortion rate is calculated as follows: A fast Fourier transform is performed on the capacitor terminal voltage to extract the amplitudes from the fundamental wave to the preset highest harmonic. The square root of the sum of the squares of the amplitudes of each harmonic is then compared with the fundamental wave amplitude to obtain the total harmonic distortion rate of the capacitor terminal voltage.

5. The method for optimizing and analyzing parameters of a capacitive reactor bank as described in claim 1, characterized in that: The process for determining whether the reactance has drifted is as follows: The current amplitude of the reactor branch calculated in the current detection cycle is compared with that in the previous detection cycle. If the current current amplitude is greater than that in the previous cycle and this state continues for three detection cycles, it serves as a trigger condition for the current amplitude to continue to increase. The fundamental voltage-current phase difference and total harmonic distortion rate are simultaneously observed within the time interval when the triggering conditions are met. If the absolute value of the phase difference increases monotonically, and the total harmonic distortion rate increases monotonically while the dominant harmonic order remains unchanged, then the reactance rate is initially suspected to be drifting. After the initial judgment is established, continue to monitor the current amplitude of the reactor branch in the next detection cycle: if the current amplitude in the next cycle is still greater than or equal to the amplitude at the beginning of the load increase, and the phase difference and total harmonic distortion rate continue to show the same monotonically increasing characteristics, then it is determined that the reactance rate has drifted. If the current amplitude in the next cycle does not show a continuous increase, but the phase difference and distortion rate still show a monotonically increasing characteristic, then further check the reactor winding temperature: If the winding temperature rises continuously during the same time period in which the phase difference and distortion rate increase monotonically, it is determined that the reactance has drifted.

6. The method for optimizing and analyzing parameters of a capacitive reactor bank as described in claim 1, characterized in that: The content regarding determining the inductor adjustment direction based on whether the winding temperature exceeds the limit is as follows: The current reactor winding temperature is detected. If it is below the safety limit, the adjustment direction is to increase the inductance. If it reaches or exceeds the safety limit, the adjustment direction is to decrease the inductance.

7. The method for optimizing and analyzing parameters of a capacitive reactor bank as described in claim 1, characterized in that: The process for determining the stable waiting window is as follows: When the capacitive reactor bank is put into operation for the first time, a self-test is performed: a test adjustment command with a preset direction and a size equal to the minimum adjustment unit of inductance is output, and high-speed sampling is started to collect the complete transient waveform of the reactor branch current from the start of adjustment to the recovery to the new steady state, and the envelope of the transient component is extracted from the waveform. The time required for the envelope to decay from its peak value to a set ratio is measured and recorded as the transient decay time constant of the reactor magnetic circuit under the current operating condition. Multiply the transient decay time constant of the reactor's magnetic circuit by the safety factor to obtain the stability waiting window.

8. The method for optimizing and analyzing parameters of a capacitive reactor bank as described in claim 1, characterized in that: The process for determining whether the adjustment direction is correct is as follows: After the stabilization waiting window ends, recalculate the absolute value of the fundamental voltage-current phase difference and the total harmonic distortion rate, and compare them with the corresponding values ​​before adjustment; If the following conditions are met simultaneously, the adjustment direction is determined to be correct, and the current inductance value is used as the new reference for the next adjustment in the same direction; otherwise, the direction is determined to be incorrect: a) The absolute value of the phase difference between the fundamental voltage and current and the total harmonic distortion rate after adjustment are both less than the corresponding values ​​before adjustment; b) The relative reduction rate of the absolute value of the fundamental voltage-current phase difference and the relative decrease rate of the total harmonic distortion rate are used to construct a two-dimensional vector. The angle between this vector and the positive direction of the horizontal axis is within the range formed by the upper limit of the cooperative angle and the lower limit of the cooperative angle.

9. The method for optimizing and analyzing parameters of a capacitive reactor bank as described in claim 1, characterized in that: The process for determining the termination condition is as follows: After confirming that the adjustment direction is correct, repeat the fixed step size adjustment along the current direction. After each adjustment, calculate the improvement amount of this adjustment, where the improvement amount is defined as the square root of the product of the relative reduction rate of the absolute value of the fundamental voltage-current phase difference and the relative reduction rate of the total harmonic distortion rate. Compare the improvement amount of this adjustment with the improvement amount of the previous adjustment: If the improvement amount in this instance is less than the improvement amount in the previous instance, the adjustment will be terminated and the result of this adjustment will be retained. If the improvement amount is zero, the adjustment will be terminated and the adjustment result will be rolled back. If the improvement amount in this instance is greater than zero and not less than the previous improvement amount, then the next adjustment will continue until the improvement amount is zero or less than the previous improvement amount, at which point the adjustment will terminate.

10. The method for optimizing and analyzing parameters of a capacitive reactor bank as described in claim 1, characterized in that: The specific process for re-verifying the adjustment command with the same step size output in the opposite direction is as follows: If the adjustment direction is incorrect, cancel the adjustment command and restore the reactor inductance value to the state before adjustment; Output adjustment commands with the same fixed step size in the opposite direction, and recalculate the absolute value of phase difference and total harmonic distortion after the stabilization waiting window ends; If the absolute value of the phase difference and the total harmonic distortion rate after adjustment are both less than before adjustment, and the angle between the vector formed by the relative reduction rate of the absolute value of the phase difference and the relative decrease rate of the total harmonic distortion rate and the positive direction of the coordinate axis is within the range formed by the upper limit of the cooperative angle and the lower limit of the cooperative angle, then the direction is confirmed to be correct, and the fixed step size adjustment is repeated along the current direction. If the direction is incorrect, the adjustment step size will be reduced to half of the original step size, the adjustment command will be output again in the opposite direction, and the calculation will be recalculated after the stabilization waiting window. If the adjustment after reducing the step size meets the correct direction condition, then the fixed step size adjustment is repeated along the current direction by reducing the step size until the termination condition is met. If two consecutive reverse adjustments of different timing lengths fail to meet the correct direction condition, the optimization will terminate and an alarm signal will be output.

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