An optimization method for reducing secondary voltage drop of a voltage transformer for a gateway table

Abstract

The application discloses an optimization method for reducing secondary voltage drop of a voltage transformer for a gateway meter, belongs to the technical field of electric power metering and secondary circuit voltage optimization, and relates to an optimization method for reducing secondary voltage drop of a voltage transformer for a gateway meter. A secondary voltage transmission circuit of the voltage transformer is modeled to form at least two switchable candidate transmission paths; reference voltage signals, voltages at ends of each candidate transmission path and transmission state information are collected to determine voltage drop deviation information and path historical state evaluation parameters, based on which comprehensive path cost is obtained and a target transmission path is determined; a pre-synchronization compensation voltage is applied before switching, a reverse compensation amount is applied after switching, reconstructed metering voltage is obtained, and joint iterative correction is carried out based on residual deviation. The method can reduce the secondary voltage drop of the voltage transformer for the gateway meter and improve the stability and accuracy of the metering voltage.

Description

Technical Field

[0001] This invention relates to the field of power metering and secondary circuit voltage optimization technology, and more specifically, to an optimization method for reducing the secondary voltage drop of voltage transformers used in metering. Background Technology

[0002] In power metering scenarios, the secondary output of a voltage transformer is typically connected to the metering terminal of a gateway meter via a secondary voltage transmission loop. Because this secondary voltage transmission loop often includes conductor segments, terminal segments, contact segments, and switching nodes, and because the transmission distance, connection level, and operating environment vary, the voltage signal is easily affected by factors such as conductor impedance, terminal contact condition, contact aging, and localized temperature rise during transmission. This results in an additional voltage drop before reaching the gateway meter's metering terminal. If this additional voltage drop persists, the metering voltage received by the gateway meter will be lower than the actual output voltage of the voltage transformer's secondary side, thus affecting the accuracy of the metering results.

[0003] In existing technologies, to reduce the voltage deviation between the secondary side of the voltage transformer and the metering terminal, methods such as increasing the conductor cross-sectional area, shortening the wiring path, optimizing terminal connections, regularly inspecting contacts, or performing offline calibration using fixed parameters are commonly used. While these methods can achieve some effect in the initial stages of equipment operation, they are essentially based on fixed transmission paths and static compensation approaches, making it difficult to reflect the dynamic changes in the secondary voltage transmission circuit during long-term operation. As conductor resistance drifts, terminal temperature rises, contact operation frequency increases, contact wear intensifies, and harmonic propagation conditions change, the original static configuration and offline calibration results will gradually deviate from the actual operating state, making it difficult for existing technologies to continuously and accurately suppress the secondary voltage drop of the voltage transformer used in metering systems.

[0004] The above problems are even more pronounced in scenarios with multiple switchable transmission paths. The line impedance parameters, switching transient response parameters, and harmonic transmission parameters of different transmission paths are usually different. When a transmission path switch occurs during operation, if there is a lack of comprehensive evaluation of the status of candidate transmission paths, lack of pre-synchronization compensation for the target transmission path before switching, and lack of reverse compensation and joint iterative correction based on residual deviation after switching, phenomena such as amplitude deviation, phase deviation, transient overshoot, and oscillation wakes can easily occur at the metering end of the gateway. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an optimized method for reducing the secondary voltage drop of the voltage transformer used in the gate meter.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an optimized method for reducing the secondary voltage drop of a voltage transformer used in a metering system, comprising:

[0007] The secondary voltage transmission circuit of the voltage transformer is modeled and divided into multiple candidate circuit segments. The multiple candidate circuit segments are combined to form at least two switchable candidate transmission paths. By describing the conductor segments, terminal segments, contact segments and switching nodes in the secondary voltage transmission circuit in a path-based manner, the reachable transmission paths under different electrical connection states can be identified and compared, thereby providing a basis for subsequent path evaluation and switching.

[0008] The reference voltage signal at the secondary output terminal of the voltage transformer, obtained through electrical isolation, is acquired. The terminal voltage and transmission status information of each candidate transmission path are also acquired. By using the reference voltage signal as a reference input, the terminal voltage and related status parameters of each candidate transmission path under actual operating conditions are obtained, thereby achieving synchronous characterization of the transmission effect and operating status of different candidate transmission paths.

[0009] The voltage drop deviation information of each candidate transmission path is determined based on the reference voltage signal and the terminal voltage, and the path history status evaluation parameters of each candidate transmission path are determined based on the transmission status information; wherein, the voltage drop deviation information is used to reflect the degree of voltage deviation of the candidate transmission path under the current transmission conditions, and the path history status evaluation parameters are used to reflect the status changes and deterioration trends of the candidate transmission path in long-term operation.

[0010] The voltage drop deviation cost corresponding to each candidate transmission path is determined based on the voltage drop deviation information, and the path historical state cost corresponding to each candidate transmission path is determined based on the path historical state evaluation parameters. The voltage drop deviation cost and the path historical state cost are normalized to obtain the comprehensive path cost corresponding to each candidate transmission path, and the target transmission path is determined accordingly. By incorporating the cost reflecting the current deviation level and the cost reflecting the long-term state into the path evaluation process, the selection of the target transmission path takes into account both the immediate voltage drop optimization capability and the long-term operational reliability.

[0011] Before switching from the current main transmission path to the target transmission path, a pre-synchronization compensation voltage is applied to the target transmission path so that the voltage difference between the target transmission path and the current main transmission path meets the preset switching conditions before the path switching is performed. By pre-adjusting the voltage of the target transmission path before switching, the disturbances caused by amplitude and phase differences during the path switching process can be reduced, and the smoothness of the path switching process can be improved.

[0012] After the path switching, a reverse compensation amount opposite to the voltage drop deviation is applied to the metering end to obtain the reconstructed metering voltage. By compensating and correcting the voltage at the metering end after the target transmission path switching is completed, the influence of the remaining voltage drop can be further offset, making the input voltage at the metering end closer to the reference voltage signal.

[0013] The reconstructed metering voltage is compared with the reference voltage signal to obtain the residual deviation. Based on the residual deviation, the path history state evaluation parameters, the pre-synchronization compensation voltage, and the reverse compensation amount are jointly iteratively corrected. By continuing to use the residual deviation after switching to reversely correct the path evaluation and compensation control parameters, a continuously optimized closed-loop regulation process is formed, thereby improving the overall optimization method's adaptability to different operating conditions.

[0014] Furthermore, the acquisition of the reference voltage signal includes: sampling the voltage at the secondary output terminal of the voltage transformer through a high-impedance sampling channel electrically isolated from the metering circuit, and extracting reference features including at least amplitude and phase information. By performing high-impedance, isolated sampling of the reference voltage signal, reference information for subsequent comparison and compensation control can be stably obtained without significantly affecting the original operating state of the metering circuit.

[0015] Furthermore, the voltage drop deviation information includes at least one or more of steady-state voltage drop deviation, switching transient deviation, and frequency domain deviation. The steady-state voltage drop deviation characterizes the steady-state amplitude deviation between the reference voltage signal and the end voltage of each candidate transmission path. The switching transient deviation characterizes the transient voltage and phase deviation between the current main transmission path and the target transmission path during the switching process. The frequency domain deviation characterizes the harmonic spectrum difference and / or frequency deviation between the reference voltage signal and the end voltage of each candidate transmission path. By characterizing the voltage drop deviation from multiple perspectives—steady-state, switching dynamics, and frequency domain characteristics—the evaluation of candidate transmission paths can be more comprehensive.

[0016] Furthermore, the transmission status information includes at least two of the following: conductor resistance parameters, terminal temperature rise parameters, contact operation frequency parameters, contact wear parameters, and harmonic distortion parameters. The transmission status information of each candidate loop segment constituting each candidate transmission path is cumulatively analyzed to obtain at least one of the following: thermal drift score component, switching disturbance score component, and frequency harmonic degradation score component. These components are then normalized and fused to obtain the historical status evaluation parameters of the path. By cumulatively modeling the long-term operating status of candidate transmission paths, the ability to identify path reliability and degradation trends can be improved.

[0017] Furthermore, regarding the first Calculate the comprehensive path cost for each candidate transmission path. Its expression is:

[0018]

[0019] in, Indicates the first Normalized voltage drop bias cost corresponding to each candidate transmission path Indicates the first The normalized path history cost corresponding to each candidate transmission path and Let be the weighting coefficient, and satisfy:

[0020]

[0021] The candidate transmission path with the lowest comprehensive path cost is determined as the target transmission path. In this way, evaluation quantities from different sources and with different dimensions can be unified into a single decision-making framework, enabling the quantitative selection of the target transmission path.

[0022] Furthermore, the pre-synchronization compensation voltage includes: applying a first compensation voltage at the switching node of the target transmission path to converge the voltage amplitude difference and phase difference between the target transmission path and the current main transmission path to a preset range; and applying a second compensation voltage during the path switching process to suppress transient overshoot and / or voltage oscillations caused by the path switching. By configuring compensation voltages for different operating stages before and after the switching, the smoothness of the path switching process can be improved, and the impact of the switching process on the voltage quality at the metering end can be reduced.

[0023] Furthermore, the reverse compensation amount is jointly determined by the immediate compensation term and the memory compensation term, in the first... In the next iteration of correction, the following condition is satisfied:

[0024]

[0025] in, Indicates the first The reverse compensation amount generated in the next iteration of correction. Indicates the first The immediate compensation term determined in the next iteration of correction for the current residual bias. Indicates according to the first The memory compensation term is determined by the residual bias after the next iteration of correction. and This is the compensation coefficient;

[0026] The direction of the reverse compensation amount is opposite to the direction of the current residual deviation.

[0027] Furthermore, the joint iterative correction includes: using the residual deviation to synchronously update the path historical state evaluation parameters, the pre-synchronization compensation voltage, and the compensation coefficient, and redetermining the reverse compensation amount based on the updated compensation coefficient, in order to perform the next round of candidate transmission path evaluation, path switching, and metering voltage correction. Through this joint iterative approach, path evaluation, pre-synchronization switching control, and metering compensation control can continuously and adaptively optimize during operation.

[0028] Furthermore, when the residual deviation exceeds a preset threshold for N consecutive sampling periods, and the path historical state evaluation parameter continuously rises and exceeds a preset protection threshold, switching between ordinary candidate transmission paths is stopped and the current main transmission path is maintained; when a preset protection candidate transmission path exists, switching to the preset protection candidate transmission path is initiated; wherein, the preset protection candidate transmission path is a candidate transmission path that meets preset transmission constraints and whose path historical state evaluation parameter is not higher than a preset upper limit, and the pre-synchronization compensation voltage and the reverse compensation amount are limited within a preset safety adjustment range. By setting a protective switching mechanism, repeated switching of the metering circuit can be prevented under abnormal operating conditions, and the overall operational safety can be improved.

[0029] Furthermore, the candidate loop segment includes at least two of the following: conductor segment, terminal segment, contact segment, and switching node; multiple candidate loop segments are combined according to preset electrical connection relationships and switchable connection states to form different candidate transmission paths, and different candidate transmission paths correspond to at least one of different line impedance parameters, path switching transient response parameters, and harmonic transmission parameters. By providing a detailed description of the candidate loop segments and their connection relationships, the feasibility of forming and evaluating candidate transmission paths can be enhanced.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] In this invention, the secondary voltage transmission circuit of the voltage transformer is modeled and divided into multiple candidate circuit segments. Based on each candidate circuit segment, at least two switchable candidate transmission paths are formed. Simultaneously, reference voltage signals, the end voltages of each candidate transmission path, and transmission status information are collected to further determine voltage drop deviation information and path history status evaluation parameters. Based on this, a comprehensive path cost is obtained to determine the target transmission path. Through these technical means, the original fixed and static secondary voltage transmission path optimization method can be transformed into a dynamic path selection method oriented towards actual operating conditions. Therefore, even under conditions such as changes in conductor impedance, terminal temperature rise, and contact status, the candidate transmission path with the lowest voltage drop level and the best operating condition can still be preferentially selected, which is beneficial for reducing the secondary voltage drop of the voltage transformer at the source. Attached Figure Description

[0032] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0033] Figure 1 This is a flowchart of the optimization method for secondary voltage drop according to the present invention. Detailed Implementation

[0034] 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 a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0036] like Figure 1 As shown, this invention provides an optimized method for reducing the secondary voltage drop of a voltage transformer used in a metering system. In a specific implementation scenario, the metering system is installed in a metering cabinet, and the voltage transformer is used to obtain the primary circuit voltage. The secondary output of the voltage transformer is connected to the metering terminal of the metering system through a secondary voltage transmission circuit. Because the distance between the secondary output of the voltage transformer and the metering terminal of the metering system typically involves long wire lengths, numerous terminals, long-term contact operation, local temperature fluctuations, and changes in harmonic transmission conditions, additional voltage drops are easily generated in the secondary voltage transmission circuit. Furthermore, transient overshoot, voltage oscillations, and phase shifts may occur during transmission path switching, thereby affecting the metering accuracy of the metering system. To reduce the secondary voltage drop of the voltage transformer used in the metering terminal and improve the stability and consistency of the metering voltage, this embodiment models the secondary voltage transmission circuit of the voltage transformer, forming multiple candidate circuit segments and at least two switchable candidate transmission paths. In the selection of candidate transmission paths, path switching, and metering voltage correction after switching, a comprehensive path cost evaluation, pre-synchronization compensation voltage, and reverse compensation amount are introduced to achieve continuous optimization of the metering terminal input voltage.

[0037] In this embodiment, the rated output voltage of the secondary side of the voltage transformer is The rated frequency is Three physically independent candidate transmission paths, selectable via switching nodes, are pre-laid from the secondary output of the voltage transformer to the metering terminal. These paths are designated as a first candidate transmission path, a second candidate transmission path, and a preset protection candidate transmission path. The first candidate transmission path consists of a first conductor segment, a first terminal segment, a first contact segment, a common switching node, an end conductor segment, and a metering terminal segment, in that order. The second candidate transmission path consists of a second conductor segment, a second terminal segment, a second contact segment, the common switching node, an end conductor segment, and a metering terminal segment, in that order. The preset protection candidate transmission path consists of a shielded conductor segment, a dedicated protection terminal segment, a protection contact segment, the common switching node, a protection short conductor segment, and a protection terminal segment, in that order. The conductor segments, terminal segments, contact segments, and switching nodes in each of these paths are recorded and managed as candidate loop segments. Therefore, a candidate loop segment includes at least two of the following: conductor segments, terminal segments, contact segments, and switching nodes.

[0038] To ensure a clear electrical connection basis for the formation of candidate transmission paths, a secondary voltage transmission loop connection table is established in the controller's memory. This table records at least the following: the number of each candidate loop segment, loop segment type, start node, end node, whether participation in path switching is permitted, current connectivity status, associated sampling channel, initial line parameters, and historical status records. The start and end nodes reflect preset electrical connection relationships, while the permission to participate in path switching and current connectivity status reflect switchable connection states. Starting from the secondary output node of the voltage transformer, the controller traverses to the metering end node of the gate meter according to the preset electrical connection relationships in the secondary voltage transmission loop connection table. After eliminating candidate loop segments in an open state and those set as non-switchable, all actually reachable paths are retained, thus forming multiple candidate transmission paths. These candidate transmission paths are not arbitrarily pieced together but are valid paths generated based on actual wiring relationships, real-time connectivity status, and switching permission conditions. Therefore, modeling and candidate path generation can be directly completed based on the on-site loop connection relationships.

[0039] To obtain the reference voltage, the reference voltage signal is acquired from the secondary output of the voltage transformer via a high-impedance sampling channel electrically isolated from the metering circuit. The high-impedance sampling channel sequentially comprises a high-impedance sampling network, an isolation amplifier, a low-pass anti-aliasing filter, and an analog-to-digital converter. The input impedance of the high-impedance sampling network is set to... The above are preferred. to To reduce the impact of the sampling process on the original voltage distribution on the secondary side of the voltage transformer, an isolation amplifier is used to achieve electrical isolation from the metering circuit, preventing the sampling device from forming an additional grounding branch for the metering circuit. The cutoff frequency of the low-pass anti-aliasing filter is preferably set to 20 to 40 times the fundamental frequency of the power frequency to retain the main harmonic information and suppress ultra-high frequency noise. The sampling frequency of the analog-to-digital converter is preferably 256, 512, or 1024 points per cycle. In this embodiment, a sampling method of 512 points per cycle is used, and a complete power frequency cycle analysis period is 20ms. After the controller synchronously samples the output voltage of the secondary side of the voltage transformer, it retains its time-domain waveform data and further extracts reference features including at least amplitude and phase information. The amplitude information is calculated from the effective value within one power frequency cycle, and the phase information is obtained by the phase-locked loop algorithm relative to the internal standard sine reference. If necessary, frequency information and harmonic component information are also extracted. The time-domain waveform data and its corresponding features obtained thereby constitute the reference voltage signal.

[0040] To obtain the actual output state of each candidate transmission path, an end sampling branch is set up near the metering end of each candidate transmission path. Each end sampling branch includes a high-impedance sampling network, an isolation amplifier, and an analog-to-digital converter, with the same circuit structure as the high-impedance sampling channel of the reference voltage signal, except that the sampling position is set at the end of the corresponding candidate transmission path. The voltage collected by the end sampling branch is the end voltage, which is used to characterize the actual end voltage of the corresponding candidate transmission path transmitted to the vicinity of the metering end at the current moment. The controller synchronously samples the reference voltage signal and the end voltage of each candidate transmission path with a unified clock to ensure that the sampling time deviation between each sampling channel is less than 1. This ensures that when calculating amplitude difference, phase difference, and frequency domain difference, the comparison objects come from the same time or the same analysis period, avoiding additional errors introduced by asynchronous sampling.

[0041] In addition to voltage sampling information, transmission status information for each candidate transmission path and its candidate loop segment also needs to be collected. This transmission status information includes at least two of the following: conductor resistance parameters, terminal temperature rise parameters, contact actuation count parameters, contact wear parameters, and harmonic distortion parameters. In this embodiment, all five types of parameters are collected. The initial value of the conductor resistance parameter is obtained through pre-operation calibration. During calibration, with the actual metering input at the disconnect switch, a known test signal is applied to each candidate transmission path, and the equivalent conductor resistance parameter is obtained based on the voltage difference between the beginning and end of the candidate path and the test current. During operation, this parameter is corrected based on the reference voltage signal, the end voltage, and historical operating data. The terminal temperature rise parameter is collected by temperature sensors deployed near each terminal segment, and then subtracted from the ambient temperature inside the metering cabinet to obtain the temperature rise value reflecting the local heating degree of the terminal. The contact actuation count parameter is recorded by the auxiliary contact counter of the switching actuator, incrementing by one for each opening or closing action. Contact wear parameters are comprehensively estimated by considering the contact voltage drop after contact closure, contact bounce duration, and cumulative number of operations. Specifically, when the same contact segment exhibits a larger contact voltage drop and a longer bounce recovery time after closure, its contact wear parameters are correspondingly higher. Harmonic distortion parameters are obtained by performing a discrete Fourier transform on the terminal voltages of each candidate transmission path. In this embodiment, the amplitude ratios of the third, fifth, seventh, and eleventh harmonics are selected and weighted to form the harmonic distortion parameters of the candidate transmission path.

[0042] The voltage drop deviation information of each candidate transmission path is determined based on the reference voltage signal and the terminal voltage. The voltage drop deviation information includes at least one or more of steady-state voltage drop deviation, switching transient deviation, and frequency domain deviation. In this embodiment, all three are involved in the calculation. The steady-state voltage drop deviation characterizes the steady-state amplitude deviation between the reference voltage signal and the terminal voltage of each candidate transmission path. It is calculated by obtaining the effective value of the reference voltage signal within the normal operating cycle during which no path switching occurs. and the RMS value of the end voltage of the candidate transmission path And calculate the absolute difference between the two. To eliminate the influence of dimensions under different rated voltage scenarios, the difference is then divided by the effective value of the reference voltage signal to obtain the first... The normalized steady-state voltage drop deviation of each candidate transmission path. The switching transient deviation characterizes the transient voltage and phase deviation between the current main transmission path and the target transmission path during the switching process. Specifically, two power frequency cycles of data are captured before and after the path switching command is issued, forming a switching analysis window lasting 80ms. Within this analysis window, the instantaneous amplitude difference between the reference voltage signal and the corresponding terminal voltage of the target transmission path is calculated point by point, and the maximum instantaneous amplitude deviation is extracted. Simultaneously, the phase trajectory is compared, and the maximum instantaneous phase deviation is extracted. The maximum instantaneous amplitude deviation and the maximum instantaneous phase deviation are then combined according to a preset ratio to form the switching transient deviation. The frequency domain deviation characterizes the harmonic spectrum difference and / or frequency deviation between the reference voltage signal and the terminal voltages of each candidate transmission path. The controller performs discrete Fourier transform on the reference voltage signal and the terminal voltages of each candidate transmission path to obtain the amplitude of each major harmonic component, and then normalizes and sums the differences at each frequency point. If frequency drift exists, the frequency deviation is superimposed on the frequency domain deviation according to a preset ratio.

[0043] To enable voltage drop deviation information to be directly used for subsequent path selection, this implementation further converts steady-state voltage drop deviation, switching transient deviation, and frequency domain deviation into voltage drop deviation costs. Voltage drop deviation cost corresponding to each candidate transmission path Calculated according to the following rules:

[0044]

[0045] in, Indicates the first Normalized steady-state voltage drop deviation of candidate transmission paths, Indicates the first Normalized switching transient bias of candidate transmission paths, Indicates the first Normalized frequency domain offset of candidate transmission paths, , and Let represent the weighting coefficients for steady-state voltage drop deviation, switching transient deviation, and frequency domain deviation, respectively, and satisfy the following:

[0046] In this embodiment, it is preferred to set , , When the focus on the stability of the switching process is greater on-site, it can be improved. The value of can be increased when the background harmonics of the power grid are strong. The value of is thus determined. Therefore, the pressure drop deviation information is uniformly mapped from three different dimensions to a comparable pressure drop deviation cost.

[0047] Based on the transmission status information, path history status evaluation parameters for each candidate transmission path are determined. To ensure these parameters have a clear source and a repeatable calculation process, the controller performs cumulative analysis on the transmission status information of each candidate loop segment constituting each candidate transmission path. Here, "cumulative analysis" refers to: in the most recent Within each analysis period, the state variables of each candidate loop segment involved in the same candidate path are first normalized according to the loop segment type, then an exponentially weighted average is performed in the time dimension, and finally a weighted summary is performed in the path dimension. Let the most recent... Each analysis period is denoted as... The more recent the analysis period, the greater the time weight. In this embodiment, let the time weight coefficient be... ,and Preferred selection For the first The controller generates thermal drift score components for each of the candidate transmission paths. Switching perturbation scoring components Sum of frequency harmonic degradation score components Among them, the thermal drift score component The voltage drop deviation is determined by the rate of change of conductor resistance parameters in each conductor segment within the candidate transmission path, the terminal temperature rise parameters in each terminal segment, and the historical steady-state voltage drop deviation drift value of the corresponding path. Specifically, the greater the rate of change of conductor resistance parameters, the greater the terminal temperature rise parameters, and the more significant the historical steady-state voltage drop deviation drift, the better. The larger the value, the better. Switch the perturbation score component. The parameter is determined by the number of contact actions, contact wear parameters, and the exponentially weighted average of transient deviations from previous switching operations for the candidate transmission path. A higher number of contact actions, more severe contact wear, and greater transient deviations from past switching operations result in a higher probability of contact action frequency. The larger the frequency harmonic degradation score component. The frequency domain deviation is determined by the harmonic distortion parameters and the long-term cumulative value of the frequency domain deviation of the candidate transmission path. The larger the harmonic distortion parameters and the higher the long-term cumulative frequency domain deviation, the better. The larger.

[0048] In order to unify multiple scoring components into a path history state evaluation parameter, this implementation method stipulates: first, , and Normalized to The intervals are then merged according to a preset ratio to obtain the first interval. Path history status evaluation parameters of candidate transmission paths :

[0049]

[0050] in, , and Let represent the weighting coefficients of the thermal drift score component, the switching disturbance score component, and the frequency harmonic degradation score component, respectively, and satisfy the following:

[0051] In this embodiment, it is preferred to take , , The path historical status evaluation parameters The higher the value, the worse the candidate transmission path's long-term operating condition, and the higher the risk of further significant voltage drops or switching disturbances in the future. To maintain consistency with subsequent comprehensive path cost calculations, [the following will be used]. Further normalization yields the normalized path historical state cost. .

[0052] After determining the voltage drop deviation cost corresponding to each candidate transmission path based on the voltage drop deviation information, it is further normalized to obtain the first... Normalized voltage drop bias cost corresponding to each candidate transmission path In this implementation, a minimum-maximum normalization method is used. Within the current candidate path set, the maximum and minimum pressure drop deviation costs of all candidate paths are taken, and the... The voltage drop bias cost of each candidate transmission path is mapped to Interval. Subsequently, according to the... Normalized voltage drop bias cost corresponding to each candidate transmission path and the cost of normalized path historical state Calculate the comprehensive path cost Its expression is:

[0053]

[0054] in, and Let be the weighting coefficient, and satisfy: .

[0055] In this embodiment, the initial commissioning phase is taken as follows: , Prioritize and quickly reduce the secondary voltage drop; after the system stabilizes, the controller can adjust the settings based on the long-term convergence of the residual deviation. Adjust to 0.6, The value was adjusted to 0.4 to enhance the consideration of the long-term state of candidate transmission paths. The controller calculates the comprehensive path cost for each candidate transmission path. The candidate transmission path with the lowest overall path cost is then selected as the target transmission path. This approach considers both the current voltage drop level and the long-term health and future operational risks of the path.

[0056] Before switching from the current main transmission path to the target transmission path, a pre-synchronization compensation voltage is applied to the target transmission path. For this purpose, a compensation injection branch is set at the switching node of the target transmission path. The compensation injection branch sequentially includes an isolation compensation source, a digital-to-analog converter, a power drive amplifier, and a coupling transformer. The controller synthesizes a first compensation voltage matching the output state of the current main transmission path based on the terminal voltage corresponding to the current main transmission path and the amplitude and phase information of the reference voltage signal, and applies it to the switching node of the target transmission path through the compensation injection branch. The function of the first compensation voltage is to ensure that the target transmission path is in a voltage state approximately consistent with the current main transmission path before the formal switching, thereby converging the voltage amplitude difference and phase difference between the target transmission path and the current main transmission path to a preset range. In this embodiment, the preset range can be set as follows: the voltage amplitude difference does not exceed... Phase difference not exceeding The controller recalculates the difference between the end state of the target transmission path and the current main transmission path state every sampling period. When both satisfy the preset range for three consecutive analysis periods, the pre-synchronization is considered to be completed.

[0057] During path switching, to further suppress transient overshoot and / or voltage oscillations caused by path switching, the controller continues to apply a second compensation voltage through the compensation injection branch. The duration of the second compensation voltage covers the entire process of the switching actuator's operation, and in this embodiment, it is taken as 30ms to 60ms. The initial waveform of the second compensation voltage is obtained by fitting historical switching transient deviation data, specifically using an exponentially decaying sine wave or a piecewise linear compensation waveform. When historical data is lacking for the first commissioning in the field, an empirical damped waveform can be used as the second compensation voltage initially, and then gradually corrected in subsequent joint iterative corrections. The switching actuator uses a relay group with auxiliary contacts. The auxiliary contacts feed back the actual action time and connection status to the controller, so that the controller can correct the switching transient deviation calculation window and the application timing of the second compensation voltage.

[0058] After the path switching is completed, a reverse compensation amount opposite to the voltage drop deviation is applied at the metering end to obtain the reconstructed metering voltage. For this purpose, a metering end compensation injection branch is connected in series before the metering end of the gateway meter. This branch includes, in sequence, an isolation compensation power supply, a digital-to-analog converter, a driver amplifier, and a series compensation transformer. The voltage at the end of the target transmission path and the reverse compensation amount output from the metering end compensation injection branch are superimposed at the metering end of the gateway meter to form the reconstructed metering voltage. This reconstructed metering voltage is used to provide the gateway meter with the actual metering input voltage after path optimization and compensation correction; therefore, it should approximate the reference voltage signal as closely as possible.

[0059] To clarify the source and parameter meaning of the reverse compensation amount, this implementation specifies that the reverse compensation amount is jointly determined by the instantaneous compensation term and the memory compensation term, and is determined in the first... In the next iteration of correction, the following condition is satisfied:

[0060]

[0061] in, Indicates the first The reverse compensation amount generated in the next iteration of correction, and This is the equivalent voltage compensation amount mapped to the metering terminal; Indicates the first The instantaneous compensation term determined based on the current residual bias in the next iteration of correction, and Similarly, this is the voltage equivalent compensation amount mapped to the metering terminal; Indicates according to the first The memory compensation term is determined by the residual bias after the next iteration of correction, and This is also the equivalent voltage compensation amount mapped to the metering terminal; and These are compensation coefficients, all of which are dimensionless. Because... , and Since they have the same dimensions, the above formulas are dimensionally consistent. The negative sign indicates that the direction of the reverse compensation amount is opposite to the direction of the current residual bias.

[0062] Furthermore, the aforementioned immediate compensation item The source is as follows. The controller will... At the next iteration of correction, the reconstructed metering voltage and the reference voltage signal are synchronously compared to obtain the residual voltage amplitude deviation. and phase residual deviation Since the compensation at the metering end of the gateway meter applies to voltage, it is necessary to map the phase residual deviation to an equivalent voltage deviation. In this embodiment, the phase residual deviation is converted into the corresponding equivalent voltage deviation using the amplitude of the reference voltage signal, denoted as […]. Then, the residual amplitude deviation and the corresponding voltage equivalent deviation of the phase are fused according to a preset ratio to form an instantaneous compensation term. :

[0063]

[0064] in, and Let be the fusion coefficient, and satisfy:

[0065] In this embodiment, it is preferred to take , Thus, immediate compensation items The residual deviation from the current moment can quickly reflect the difference between the current reconstructed metering voltage and the reference voltage signal.

[0066] The memory compensation item The source is as follows. The controller will... The residual bias after the next iteration of correction is retained as the historical bias and a decay factor is applied. Inherited from it, the first The memory compensation term used in the next iteration of correction:

[0067]

[0068] in, Preferred selection Therefore, memory compensation terms Simultaneously carrying information from the previous round's immediate compensation term and even earlier historical compensation term information, it can characterize the persistent trend of residual bias in previous iterations. If the residual bias maintains the same direction over multiple analysis periods, the amplitude of the memory compensation term will gradually increase; if the residual bias direction reverses multiple times, the memory compensation term will gradually decrease due to decay. This setting helps improve the stability of the reverse compensation amount and suppress excessive oscillations.

[0069] The reconstructed metering voltage is compared with the reference voltage signal to obtain the residual deviation. Based on this residual deviation, the path history state evaluation parameters, the pre-synchronization compensation voltage, and the reverse compensation amount are jointly iteratively corrected. The joint iterative correction is performed in the following order: First, the controller calculates the current residual deviation and decomposes it into voltage amplitude residual deviation and phase residual deviation, then further forms an instantaneous compensation term. Secondly, the controller compensates for the memory retained from the previous round. and current immediate compensation items Calculate the reverse compensation amount The output is then sent to the compensation injection branch at the metering end. Next, the controller updates the compensation coefficient based on the current residual deviation magnitude and trend. and In this embodiment, the compensation coefficient update rule is as follows: when the absolute value of the current residual deviation decreases by more than a preset proportion compared to the previous round, and the deviation direction has not reversed, the proportion of the memory compensation term is increased, that is, the proportion of the memory compensation term is appropriately reduced. and appropriately increase When the absolute value of the current residual deviation does not decrease significantly or the direction reverses, increase the proportion of the immediate compensation term, that is, appropriately increase the percentage of the immediate compensation term. and appropriately reduce To avoid drastic fluctuations in the compensation coefficient, this implementation method is limited. and The single-round adjustment amount does not exceed 0.05, and always meets the following conditions. For example, in the previous round , And when the residual bias of this round decreases sufficiently, it can be updated to , When the residual deviation in this round shows a reverse amplification, it can be updated to... , .

[0070] After updating the compensation coefficients, the controller also adjusts the pre-synchronization compensation voltage based on the current switching results and the residual deviation of this round. The specific adjustment rules are as follows: if a large amplitude deviation occurs after a path switch but a small phase deviation, the amplitude correction ratio of the next first compensation voltage is increased; if a large phase deviation occurs after a path switch but a small amplitude deviation, the phase correction ratio of the next first compensation voltage is increased; if a significant transient overshoot occurs within the path switching analysis window, the peak value of the second compensation voltage is appropriately increased or its duration is extended; if a significant oscillation wake occurs within the path switching analysis window, the damping coefficient of the second compensation voltage is increased. In this way, the pre-synchronization compensation voltage gradually approaches a state more suitable for the current loop characteristics with each switching result.

[0071] Meanwhile, the controller updates the path historical state evaluation parameters using the current residual bias. Specifically, if a candidate transmission path, after being selected as the target transmission path and completing the handover, still exhibits a high residual bias for multiple consecutive analysis cycles, it indicates that the long-term state of the candidate transmission path is worse than previously estimated. In this case, the controller incrementally corrects the thermal drift score component, handover disturbance score component, or frequency harmonic degradation score component corresponding to the candidate transmission path, and regenerates new path historical state evaluation parameters. If the residual bias of the candidate transmission path remains small after the handover and compensation are completed, the corresponding score components are appropriately attenuated. Thus, the path historical state evaluation parameters are no longer static values, but dynamic parameters that are continuously updated based on actual operating results.

[0072] After the aforementioned joint iterative correction is completed, the controller is based on the updated path history state evaluation parameters, the updated pre-synchronization compensation voltage, and the updated compensation coefficients. and The comprehensive path cost of each candidate transmission path is recalculated, and the next round of candidate transmission path evaluation, path switching, and metering voltage correction is performed. In this way, candidate transmission path selection, path switching control, and metering-end reverse compensation form a closed-loop operation process. As the operating time increases, the controller's understanding of each candidate transmission path will become closer to the actual state, and the generation of compensation voltage will become more and more accurate.

[0073] To improve safety under abnormal operating conditions, this embodiment also includes a preset protection candidate transmission path switching mechanism. When the residual deviation is continuous... When a sampling period exceeds a preset threshold, and the path historical state evaluation parameter continuously rises and exceeds a preset protection threshold, the controller stops switching between ordinary candidate transmission paths and maintains the current main transmission path. Preferably, the value is 20 to 50; in this embodiment, it is taken as 20. The preset threshold preferably corresponds to The equivalent residual deviation; the preset protection threshold can be a path historical state evaluation parameter greater than 0.75. When a preset protection candidate transmission path exists, the controller further determines whether the preset protection candidate transmission path meets the preset transmission constraints. The preset transmission constraints include: steady-state voltage drop deviation does not exceed a preset upper limit, frequency domain deviation does not exceed a preset frequency domain tolerance, the switching node has normal operating capability, and the path historical state evaluation parameter is not higher than a preset upper limit. When the above conditions are met, the controller switches to the preset protection candidate transmission path and limits the pre-synchronization compensation voltage and the reverse compensation amount within a preset safety adjustment range. In this embodiment, the peak value of the pre-synchronization compensation voltage is limited to... Within this range, the peak value of the reverse compensation is limited to [value missing]. Within this range. This avoids introducing new measurement risks due to overcompensation in protection mode.

[0074] The following describes the implementation method of this method using a specific operational process. During initial commissioning, the first candidate transmission path is the current main transmission path. After continuous sampling by the controller, it is found that the first candidate transmission path has a large steady-state voltage drop deviation, a significant increase in its conductor resistance parameter, a high terminal temperature rise parameter, and a large cumulative number of contact action times. Therefore, its thermal drift score component and switching disturbance score component are both high. The second candidate transmission path has a smaller steady-state voltage drop deviation, a lower terminal temperature rise parameter, and a smaller contact wear parameter. Its path history status evaluation parameter is lower than that of the first candidate transmission path. The preset protection candidate transmission path has a moderate steady-state voltage drop deviation, but the lowest harmonic distortion parameter, and its path is relatively short. The controller calculates the voltage drop deviation cost for each of the three paths. Historical status evaluation parameters of the path Normalized pressure drop bias cost Normalization path historical state cost and comprehensive path cost Ultimately, the second candidate transmission path was determined to have the lowest overall path cost, and therefore it was selected as the target transmission path.

[0075] Subsequently, the controller generates a first compensation voltage based on the end voltage of the current main transmission path and injects it into the switching node of the second candidate transmission path. After three analysis cycles, it is found that the voltage amplitude difference between the target transmission path and the current main transmission path is less than [value missing]. Phase difference less than Therefore, the switching actuator is driven to complete the path switching. During the switching actuator operation, the controller synchronously outputs a second compensation voltage to suppress transient overshoot and voltage oscillation. After the switching is completed, the metering terminal at the gate receives the new target transmission path output voltage, and after comparison, it is found that the voltage still exists before the reconstruction. The residual bias is accompanied by a small phase residual bias. The controller generates an instantaneous compensation term based on the current residual bias. Combined with the initial memory compensation term and compensation coefficient , Calculate the reverse compensation amount The corresponding reverse compensation amount is output through the metering end compensation injection branch. After three consecutive iterative corrections, the residual deviation between the reconstructed metering voltage and the reference voltage signal at the metering end of the gate meter decreases to [value missing]. Within this range, the residual phase error decreased to Within this range, it indicates that the current path selection and compensation control are effective.

[0076] If, during subsequent long-term operation, the number of operations of the contact segment corresponding to the second candidate transmission path continues to increase, the contact wear parameters gradually rise, and the switching transient deviation of this path increases again, then its switching disturbance score component will increase, thereby raising the path's historical state evaluation parameters. and the cost of the historical state of the normalization path When the combined path cost of the second candidate transmission path is no longer the minimum, the controller will re-compare all candidate transmission paths and determine a new target transmission path. If the combined path costs of all ordinary candidate transmission paths are too high, and the residual deviations are continuous... If a sampling period exceeds a preset threshold, the system enters the preset protection candidate transmission path determination process. If the preset protection candidate transmission path meets the preset transmission constraints, the controller switches to the preset protection candidate transmission path and continues to apply pre-synchronization compensation voltage and reverse compensation amount within the limited safety adjustment range, thereby maintaining the acceptable stability of the metering terminal input voltage.

[0077] By modeling the secondary voltage transmission circuit of the voltage transformer and forming multiple candidate circuit segments and at least two switchable candidate transmission paths, the controller can identify the optimal transmission path under actual wiring conditions. Through the synchronous acquisition of reference voltage signals, terminal voltages, and transmission status information, the controller can simultaneously grasp the current voltage drop state and long-term degradation state of the path. By converting steady-state voltage drop deviation, switching transient deviation, and frequency domain deviation into voltage drop deviation costs, and converting thermal drift score components, switching disturbance score components, and frequency harmonic degradation score components into path historical state evaluation parameters, the comprehensive path cost can more comprehensively reflect the actual advantages and disadvantages of candidate transmission paths. By applying a pre-synchronization compensation voltage before switching, a second compensation voltage during path switching, and a reverse compensation amount at the metering end after switching, the voltage surge caused by switching can be reduced, and the residual voltage drop at the metering end of the gate meter can be decreased. By using the residual deviation to perform joint iterative correction of the path historical state evaluation parameters, pre-synchronization compensation voltage, and reverse compensation amount, the path selection and compensation control can be continuously optimized during operation. By setting preset protection candidate transmission paths and preset safety adjustment ranges, the metering circuit of the gate meter can still maintain stability under abnormal operating conditions.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. An optimized method for reducing the secondary voltage drop of a voltage transformer used in a metering system, characterized in that, include: The secondary voltage transmission circuit of the voltage transformer is modeled and divided into multiple candidate circuit segments. The multiple candidate circuit segments are combined to form at least two switchable candidate transmission paths. Collect the reference voltage signal at the secondary output terminal of the voltage transformer obtained through electrical isolation, and collect the end voltage and transmission status information of each candidate transmission path. The voltage drop deviation information of each candidate transmission path is determined based on the reference voltage signal and the terminal voltage, and the path history status evaluation parameters of each candidate transmission path are determined based on the transmission status information. The voltage drop deviation cost corresponding to each candidate transmission path is determined based on the voltage drop deviation information, and the path history state cost corresponding to each candidate transmission path is determined based on the path history state evaluation parameters; the voltage drop deviation cost and the path history state cost are normalized to obtain the comprehensive path cost corresponding to each candidate transmission path, and the target transmission path is determined accordingly. Before switching from the current main transmission path to the target transmission path, a pre-synchronization compensation voltage is applied to the target transmission path so that the voltage difference between the target transmission path and the current main transmission path meets the preset switching conditions before the path switching is performed. After the path switching, a reverse compensation amount opposite to the voltage drop deviation direction is applied at the metering end to obtain the reconstructed metering voltage; The reconstructed metering voltage is compared with the reference voltage signal to obtain the residual deviation, and the path history state evaluation parameters, the pre-synchronization compensation voltage, and the reverse compensation amount are jointly iteratively corrected based on the residual deviation.

2. The optimization method according to claim 1, characterized in that, The acquisition of the reference voltage signal includes: sampling the voltage at the secondary output terminal of the voltage transformer through a high-impedance sampling channel that is electrically isolated from the metering circuit, and extracting reference features that include at least amplitude and phase information.

3. The optimization method according to claim 1, characterized in that, The voltage drop deviation information includes at least one or more of steady-state voltage drop deviation, switching transient deviation, and frequency domain deviation; The steady-state voltage drop deviation is used to characterize the steady-state amplitude deviation between the reference voltage signal and the end voltage of each candidate transmission path. The switching transient deviation is used to characterize the transient voltage deviation and phase deviation between the current main transmission path and the target transmission path during the switching process. The frequency domain deviation is used to characterize the harmonic spectrum difference and / or frequency deviation between the reference voltage signal and the end voltage of each candidate transmission path.

4. The optimization method according to claim 1, characterized in that: The transmission status information includes at least two of the following: wire resistance parameters, terminal temperature rise parameters, contact actuation count parameters, contact wear parameters, and harmonic distortion parameters. The transmission status information of each candidate loop segment constituting each candidate transmission path is cumulatively analyzed to obtain at least one of the thermal drift score component, the switching disturbance score component, and the frequency harmonic degradation score component, and then normalized and fused to obtain the historical status evaluation parameters of the path.

5. The optimization method according to claim 4, characterized in that, For the Calculate the comprehensive path cost for each candidate transmission path. Its expression is: ； in, Indicates the first Normalized voltage drop bias cost corresponding to each candidate transmission path Indicates the first The normalized path history cost corresponding to each candidate transmission path and Let be the weighting coefficients, and satisfy: ； The candidate transmission path with the lowest integrated path cost is determined as the target transmission path.

6. The optimization method according to claim 1, characterized in that... The pre-synchronization compensation voltage includes: applying a first compensation voltage at the switching node of the target transmission path to bring the voltage amplitude difference and phase difference between the target transmission path and the current main transmission path to converge to a preset range; A second compensation voltage is applied during path switching to suppress transient overshoot and / or voltage oscillation caused by path switching.

7. The optimization method according to claim 1, characterized in that, The reverse compensation amount is jointly determined by the instantaneous compensation term and the memory compensation term, and in the [missing information]... In the next iteration of correction, the following condition is satisfied: ； in, Indicates the first The reverse compensation amount generated in the next iteration of correction. Indicates the first The immediate compensation term determined in the next iteration of correction for the current residual bias. Indicates according to the first The memory compensation term is determined by the residual bias after the next iteration of correction. and This is the compensation coefficient; The direction of the reverse compensation amount is opposite to the direction of the current residual deviation.

8. The optimization method according to claim 7, characterized in that... The joint iterative correction includes: Using the residual deviation, the path historical state evaluation parameters, the pre-synchronization compensation voltage, and the compensation coefficient are updated synchronously. and The reverse compensation amount is then re-determined based on the updated compensation coefficients to perform the next round of candidate transmission path evaluation, path switching, and metering voltage correction.

9. The optimization method according to claim 8, characterized in that, When the residual deviation is continuous When a sampling period is greater than a preset threshold and the path historical status evaluation parameter rises continuously and exceeds a preset protection threshold, the switching between ordinary candidate transmission paths is stopped and the current main transmission path is maintained. When a preset protection candidate transmission path exists, switch to the preset protection candidate transmission path; The preset protection candidate transmission path is a candidate transmission path that meets the preset transmission constraints and whose historical status evaluation parameters are not higher than the preset upper limit, and the pre-synchronization compensation voltage and the reverse compensation amount are limited to the preset safety adjustment range.

10. The optimization method according to claim 1, characterized in that, The candidate circuit segment includes at least two of the following: wire segment, terminal segment, contact segment, and switching node; Multiple candidate circuit segments are combined according to a preset electrical connection relationship and a switchable connection state to form different candidate transmission paths. Different candidate transmission paths correspond to at least one of different line impedance parameters, path switching transient response parameters, and harmonic transmission parameters.

Images