Solid-state distribution transformer control system and method for improving distributed power access

Abstract

The present invention relates to the field of transformer control and discloses a solid-state distribution transformer control system and method for improving the access of distributed power sources. The control system and method are used to solve the problem that when controlling a solid-state distribution transformer, the access of distributed power sources may change, resulting in the original controller parameters being unrepresentative. The method comprises the following steps: constructing a solid-state distribution transformer with multi-port power regulation capability, setting initial control parameters, obtaining data on the affected equivalent impedance, evaluating the affected equivalent impedance data to obtain an equivalent impedance change index, determining whether the equivalent impedance has changed based on the equivalent impedance change index, and if it is determined that the equivalent impedance has changed, dynamically correcting the initial control parameters based on the equivalent impedance change index to obtain actual control parameters. The solid-state transformer output is adjusted based on the actual control parameters, thereby effectively improving the accuracy of transformer control and the reliability of energy supply.

Description

Technical Field

[0001] The present invention relates to the field of transformer control, and more particularly to a solid-state distribution transformer control system and method for improving access to distributed power sources. Background Art

[0002] With the large-scale development of renewable energy, distributed power sources are increasingly being integrated into distribution networks. To enable flexible integration and efficient energy utilization of distributed power sources, solid-state distribution transformers, a new generation of power electronic transformers, are being widely used in scenarios such as regional distribution networks, microgrids, and campus energy systems. Solid-state distribution transformers integrate high-frequency transformation, voltage regulation, and energy flow control. They not only provide voltage stability but also support bidirectional power flow regulation and power decoupling, making them a key component in supporting the integration of high-proportion distributed power sources.

[0003] To improve control accuracy and system stability, existing technologies typically employ control parameter configuration methods based on static topology models. During initial system deployment, these methods pre-calibrate parameters such as the grid topology, line impedance, and cable length, and then fix controller parameters at specific setpoints to meet steady-state control objectives within the specified scenario.

[0004] However, the above technology has at least the following technical problems:

[0005] In actual operating environments, the distribution network structure in which solid-state distribution transformers operate is often highly dynamic, typically manifested by the frequent entry and exit of distributed power sources, changes in cable lengths, switching of power source entry locations, and feeder topology reconfiguration. These factors directly alter the equivalent impedance of the local network, causing the regulation values ​​derived by the solid-state distribution transformer's internal controller based on static controller parameters to mismatch the actual system state. This not only reduces the accuracy of voltage regulation and power control but can also cause power oscillations, power quality fluctuations, false protection trips, or abnormal disconnection of distributed power sources, seriously impacting system stability and energy supply reliability. Summary of the Invention

[0006] In order to overcome the above-mentioned defects of the prior art, the present invention provides a solid-state distribution transformer control system and method for improving the access of distributed power sources, so as to solve the problems existing in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A solid-state distribution transformer control system for improving distributed power access includes: a solid-state distribution transformer construction module, which is used to construct a solid-state distribution transformer with multi-port power regulation capability and set the initial control parameters of the solid-state distribution transformer; an equivalent impedance change evaluation module, which is used to obtain equivalent impedance affected data, including actual output voltage sequence, actual output current sequence, reference target voltage sequence, controller output sequence and actual output power sequence, and obtain an equivalent impedance change index based on the evaluation of the equivalent impedance affected data, and determine whether the equivalent impedance has changed based on the equivalent impedance change index; a controller parameter dynamic adjustment module, which dynamically corrects the initial control parameters based on the equivalent impedance change index if it is determined that the equivalent impedance has changed to obtain the actual control parameters; a power quality assurance and regulation execution module, which is used to adjust the solid-state transformer output based on the actual control parameters; a data upload and remote monitoring module, which is used to upload control parameter adjustment records and real-time operation status data to a database.

[0009] Preferably, the steps of constructing a solid-state distribution transformer with multi-port power regulation capability are: constructing a traditional dual-winding industrial frequency transformer, the dual winding including a high-voltage side winding and a low-voltage side winding; connecting a front-end converter to the high-voltage side group of the industrial frequency transformer, and connecting a back-end converter to the low-voltage side group of the industrial frequency transformer to construct a three-phase four-bridge arm structure; connecting the DC sides of the front-end converter and the back-end converter to form a common DC link, and leading out a low-voltage DC port to form a three-port structure with a high-voltage AC input end, a low-voltage AC output end and a low-voltage DC output end, thereby completing the construction of a solid-state distribution transformer with multi-port power regulation capability.

[0010] Preferably, the steps for obtaining the equivalent impedance change index are: setting a detection time window, performing periodic sampling within the detection time window, setting a sampling frequency, and calculating the total number of sampling points based on the time window and the sampling frequency, obtaining the actual output voltage sequence and the actual output current sequence of the transformer within the detection time window, and evaluating the electrical response influence coefficient based on the output voltage sequence and the output current sequence; obtaining the reference target voltage sequence and the controller output sequence within the detection time window, and evaluating the control feedback influence coefficient based on the reference target voltage sequence, the actual output voltage sequence and the controller output sequence; obtaining the actual output power sequence within the detection time window, and evaluating the behavior pattern influence coefficient based on the actual output power sequence and the actual output voltage sequence; normalizing the electrical response influence coefficient, the control feedback influence coefficient and the behavior pattern influence coefficient, and evaluating the normalized electrical response influence coefficient, the control feedback influence coefficient and the behavior pattern influence coefficient to obtain the equivalent impedance change index. The specific acquisition steps are: Where, Expressed as the equivalent impedance change index, Expressed as the normalized electrical response influence coefficient, Expressed as the normalized control feedback influence coefficient, Expressed as the normalized behavioral pattern influence coefficient, 、 、 It is expressed as the weight coefficient of the normalized electrical response influence coefficient, the weight coefficient of the normalized control feedback influence coefficient, and the weight coefficient of the normalized behavior mode influence coefficient.

[0011] Preferably, the steps for obtaining the electrical response influence coefficient are: within the detection time window, the voltage mean, current mean, voltage standard deviation and current standard deviation within the set time window are calculated based on the actual output voltage sequence and the actual output current sequence; the voltage standard deviation is calculated by ratio with the voltage mean to obtain the voltage variation coefficient, and the current standard deviation is calculated by ratio with the current mean to obtain the current variation coefficient; the voltage variation coefficient and the current variation coefficient are added and then averaged to obtain the electrical response influence coefficient.

[0012] Preferably, the control feedback influence coefficient acquisition step is: subtract the actual output voltage value in the actual output voltage sequence from the reference target voltage value in the reference target voltage sequence to obtain the voltage deviation value of each sampling point, perform ratio calculation on the voltage deviation value and the reference target voltage value to obtain the residual deviation rate of each sampling point, perform mean calculation on the residual deviation rate of each sampling point to obtain the normalized residual deviation rate; calculate the controller output mean value according to the controller output sequence, perform ratio calculation on the controller output mean value and the voltage deviation mean value and take the absolute value to obtain the residual misleading rate; Two sets of sampling data in the target voltage sequence and the actual output voltage sequence are considered and standardized respectively; using the enumeration method, one set of data is shifted forward or backward by different time points one by one, and the matching degree between the two sets of standardized data, that is, the cross-correlation value, is calculated at each shift position. The number of shift points corresponding to the maximum cross-correlation value is selected and recorded as the cross-correlation peak delay point number; the ratio of the cross-correlation peak delay point number to the total number of sampling points is calculated to obtain the residual hysteresis rate; the control feedback influence coefficient is calculated based on the normalized residual deviation rate, the residual misleading rate and the residual hysteresis rate.

[0013] Preferably, the step of obtaining the behavior pattern influence coefficient is as follows: obtaining the number of times the power change direction is reversed according to the actual output power sequence, recorded as the number of power reversals, and calculating the ratio of the number of power reversals to the total number of sampling points to obtain the reverse jump rate; setting a voltage threshold window, obtaining the number of times the output voltage value exceeds the voltage threshold window range within the detection time window, recorded as the number of cross-border times, and calculating the ratio of the number of cross-border times to the total number of sampling points to obtain the cross-border rate; calculating the actual output power change value and the actual output voltage change value between two adjacent sampling points according to the actual output power sequence and the actual output voltage sequence; calculating the actual output power relative change amplitude and the actual output voltage relative change amplitude of each sampling point according to the actual output power change value and the actual output voltage change value between two adjacent sampling points; adding the actual output power relative change amplitude and the actual output voltage relative change amplitude to obtain the instantaneous total fluctuation amplitude of each sampling point, and averaging the instantaneous total fluctuation amplitudes at all times to obtain the average behavior fluctuation rate; and calculating the behavior pattern influence coefficient according to the reverse jump rate, the cross-border rate, and the average behavior fluctuation rate.

[0014] Preferably, the step of determining whether the equivalent impedance has changed based on the equivalent impedance change index is: comparing the equivalent impedance change index with the change threshold; if the equivalent impedance change index is greater than or equal to the change threshold, determining that the equivalent impedance has changed; if the equivalent impedance change index is less than the change threshold, determining that the equivalent impedance has not changed.

[0015] Preferably, the steps of dynamically correcting the initial control parameters according to the equivalent impedance change index to obtain the actual control parameters are: obtaining the mean value of the effective voltage and the effective current within the detection time window, calculating the ratio of the mean effective voltage to the mean effective current to obtain the current equivalent impedance estimate, obtaining the output current value in real time, multiplying the real-time output current value by the current equivalent impedance estimate to obtain the voltage feedforward compensation amount; obtaining the initial impedance value of the solid-state distribution transformer, subtracting the initial impedance value from the current equivalent impedance estimate and calculating the ratio of the current equivalent impedance estimate to the initial impedance value to obtain the impedance change rate; if the impedance change rate is greater than 0, it is determined that the impedance has increased, and the change threshold is calculated by ratio with the equivalent impedance change index; if the impedance change rate is less than 0, it is determined that the impedance has decreased, and the equivalent impedance change index is calculated by ratio with the change threshold; if the impedance change rate is equal to 0, it is determined that the impedance has not changed, and the initial control parameter is not corrected; the initial control parameter is multiplied by the correction factor to obtain the actual control parameter.

[0016] Preferably, the step of adjusting the output of the solid-state transformer according to the actual control parameters is: constructing a control reference signal based on the target set value according to the actual control parameters, and collecting the current operating status data of the solid-state distribution transformer in real time; performing difference calculation between the current real-time collected operating status data and the reference signal to obtain a deviation signal, and inputting the deviation into a PI controller to obtain a PI control output; synthesizing the PI control output with the voltage feedforward compensation amount to obtain a final control instruction; and adjusting the output of the solid-state transformer according to the final control instruction.

[0017] Preferably, a solid-state distribution transformer control method for improving distributed power access includes the following steps: Step 1: constructing a solid-state distribution transformer with multi-port power regulation capability, and setting the initial control parameters of the solid-state distribution transformer; Step 2: obtaining equivalent impedance affected data, the equivalent impedance affected data including actual output voltage sequence, actual output current sequence, reference target voltage sequence, controller output sequence and actual output power sequence, evaluating the equivalent impedance affected data to obtain an equivalent impedance change index, and determining whether the equivalent impedance has changed based on the equivalent impedance change index; Step 3: if it is determined that the equivalent impedance has changed, dynamically correcting the initial control parameters based on the equivalent impedance change index to obtain actual control parameters; Step 4: adjusting the solid-state transformer output based on the actual control parameters; Step 5: uploading the control parameter adjustment record and real-time operating status data to a database.

[0018] The technical effects and advantages of the present invention are as follows:

[0019] A solid-state distribution transformer with multi-port power regulation capability is constructed, and initial control parameters are set to obtain data on the affected equivalent impedance. The equivalent impedance change index is obtained based on the evaluation of the affected equivalent impedance data. Whether the equivalent impedance has changed is determined based on the equivalent impedance change index. If it is determined that the equivalent impedance has changed, the initial control parameters are dynamically corrected based on the equivalent impedance change index to obtain the actual control parameters. The solid-state transformer output is adjusted based on the actual control parameters, effectively improving the accuracy of transformer control and energy supply reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a structural diagram of a solid-state distribution transformer control system for improving distributed power access provided in an embodiment of the present application.

[0021] Figure 2 This is a flow chart of a solid-state distribution transformer control method for improving distributed power access provided in an embodiment of the present application. DETAILED DESCRIPTION

[0022] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. In addition, the forms of the various structures described in the following embodiments are merely examples. The solid-state distribution transformer control system and method for improving distributed power supply access involved in the present invention are not limited to the various structures described in the following embodiments. All other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] The present invention provides a solid-state distribution transformer control system for improving access to distributed power sources, such as Figure 1 As shown, the system includes:

[0024] A solid-state distribution transformer construction module is used to construct a solid-state distribution transformer with multi-port power regulation capabilities and set the initial control parameters of the solid-state distribution transformer to support subsequent dynamic control and impedance identification functions;

[0025] The control parameters include the voltage closed-loop PI gain, power regulation coefficient, and feedforward compensation term, which are used to build the basic control model of the system controller and provide a control starting point for subsequent identification of impedance changes and adaptive parameter adjustment.

[0026] In this embodiment, it should be specifically explained that the steps for constructing a solid-state distribution transformer with multi-port power regulation capability are as follows:

[0027] First, a traditional dual-winding power-frequency transformer is constructed as the electrical isolation unit for energy transmission. The dual windings, consisting of high-voltage and low-voltage windings, provide stable basic voltage transformation for subsequent power electronics modules. This power-frequency transformer not only performs the initial voltage level conversion but also isolates the energy between the high- and low-voltage ends, providing physical support for multi-port regulation.

[0028] The front-end converter (FEC) is connected to the high-voltage side of the power frequency transformer. It uses a three-phase, four-wire structure and serves as a voltage regulation and stabilization module. The FEC is used to detect and compensate for voltage fluctuations and imbalances on the high-voltage busbar of the power grid. It also acts as an actively controllable voltage source output unit, providing voltage support for the low-voltage side.

[0029] A back-end converter (BEC) is connected to the low-voltage side of the power frequency transformer to create a three-phase, four-arm structure. This supports power quality regulation functions such as harmonic compensation, reactive power compensation, and zero-sequence compensation. The BEC also has bidirectional power regulation capabilities, linking energy storage systems and DC loads to smoothly regulate the fluctuations of distributed power sources.

[0030] The DC sides of the front-end converter and the back-end converter are connected to form a common DC link, and a low-voltage DC port is brought out to form a three-port structure with a high-voltage AC input terminal, a low-voltage AC output terminal, and a low-voltage DC output terminal, thereby constructing a solid-state distribution transformer with multi-port power regulation capability.

[0031] An equivalent impedance change evaluation module is used to obtain the affected data of equivalent impedance, which includes the actual output voltage sequence, the actual output current sequence, the reference target voltage sequence, the controller output sequence, and the actual output power sequence. An equivalent impedance change index is obtained based on the affected data of equivalent impedance, and whether the equivalent impedance has changed is determined based on the equivalent impedance change index.

[0032] In this embodiment, it should be specifically explained that the steps for obtaining the equivalent impedance variation index are:

[0033] Set a detection time window, perform periodic sampling within the detection time window, set the sampling frequency, and calculate the total number of sampling points based on the time window and the sampling frequency. Obtain the actual output voltage sequence and actual output current sequence of the transformer within the detection time window, and evaluate the output voltage sequence and output current sequence to obtain the electrical response influence coefficient;

[0034] Obtain the reference target voltage sequence and the controller output sequence within the detection time window, and evaluate the control feedback influence coefficient based on the reference target voltage sequence, the actual output voltage sequence, and the controller output sequence;

[0035] Obtain the actual output power sequence within the detection time window, and evaluate the behavior pattern influence coefficient based on the actual output power sequence and the actual output voltage sequence;

[0036] The electrical response influence coefficient, control feedback influence coefficient, and behavior mode influence coefficient are normalized, and the equivalent impedance change index is obtained based on the normalized electrical response influence coefficient, control feedback influence coefficient, and behavior mode influence coefficient. The specific acquisition steps are as follows:

[0037] ;

[0038] Where, Expressed as the equivalent impedance change index, Expressed as the normalized electrical response influence coefficient, changes in equivalent impedance will affect the stability and controllability of electrical quantities to external disturbances, thereby significantly increasing the coefficient of variation of voltage and current within the sampling window. By monitoring the relative fluctuation of the electrical response, it can serve as an important basis for judging the impedance change trend. Therefore, the higher the coefficient, the greater the possibility that the system impedance deviates from the initial state, ultimately driving the equivalent impedance change index up. Expressed as the normalized control feedback influence coefficient, when the system equivalent impedance changes, the original control parameters will have difficulty accurately guiding the voltage response, resulting in an increase in the deviation between the target voltage and the actual output, a weakening of the controller output's ability to guide the error, and a significant lag in the response. These phenomena will increase indicators such as the normalized deviation, misleading rate, and hysteresis rate, ultimately increasing the control feedback influence coefficient. Therefore, the higher this coefficient, the worse the dynamic adaptability of the control closed-loop system, and the system operating state has significantly deviated from the set impedance condition, reflecting a greater possibility of equivalent impedance changes. Expressed as the normalized behavioral pattern influence coefficient, changes in equivalent impedance will disrupt the original load stability and voltage regulation balance, leading to frequent power change reversals, increased voltage crossings, and increased fluctuations per unit time, thus showing increased instability in behavioral characteristics. The behavioral pattern influence coefficient formed by comprehensively evaluating the reverse jump rate, crossing rate, and average behavioral fluctuation rate can be used as a sensitive response quantity of the system behavior level to impedance changes. The higher the coefficient, the more likely the system has deviated from the original operating state and the greater the possibility of impedance changes. 、 、 is expressed as the weight coefficient of the normalized electrical response influence coefficient, the weight coefficient of the normalized control feedback influence coefficient, and the weight coefficient of the normalized behavior mode influence coefficient, and ,For example 、 、 It can be 0.3, 0.4, 0.3, 、 、 Obtained through the Analytic Hierarchy Process, which is a multi-criteria decision-making method used to quantitatively weight the importance of multiple evaluation factors by constructing a judgment matrix and consistency test. In the present invention, for the three dimensions of electrical response influence coefficient, control feedback influence coefficient, and behavior pattern influence coefficient, experts or historical operation data are first used to give relative importance evaluations between two factors to construct a third-order pairwise comparison judgment matrix; then, the maximum eigenvector of the matrix is ​​solved by the eigenvalue method to obtain the weight coefficient of each influencing factor, and a consistency ratio check is performed to ensure that the judgment logic is reasonable, thereby providing a reliable weight basis for the weighted fusion of the equivalent impedance change index.

[0039] In this embodiment, it should be specifically explained that the steps for obtaining the electrical response influence coefficient are:

[0040] In the detection time window, the voltage mean, current mean, voltage standard deviation and current standard deviation in the set time window are calculated based on the actual output voltage sequence and the actual output current sequence;

[0041] The voltage variation coefficient is calculated by calculating the ratio of the voltage standard deviation to the voltage mean, and the current variation coefficient is calculated by calculating the ratio of the current standard deviation to the current mean;

[0042] The voltage variation coefficient and the current variation coefficient are added together and averaged to obtain the electrical response influence coefficient.

[0043] By calculating the voltage and current coefficients of variation, the effects of dimensioning can be eliminated, making the degree of fluctuation comparable. Averaging the two coefficients provides a comprehensive reflection of the system's dynamic stability in terms of both voltage control and current load response. This method, with its simple structure, clear parameter sources, and high sensitivity, effectively identifies fluctuations in electrical responses without the need for additional adjustment factors.

[0044] In this embodiment, it should be specifically explained that the steps for obtaining the control feedback influence coefficient are:

[0045] The reference target voltage value in the reference target voltage sequence is subtracted from the actual output voltage value in the actual output voltage sequence to obtain the voltage deviation value of each sampling point. The voltage deviation value is ratioed with the reference target voltage value to obtain the residual deviation rate of each sampling point. The residual deviation rate of each sampling point is averaged to obtain the normalized residual deviation rate, which represents the degree of matching.

[0046] The controller output mean is calculated based on the controller output sequence, and the ratio of the controller output mean to the voltage deviation mean is calculated and the absolute value is taken to obtain the residual misleading rate;

[0047] The two sets of sampled data in the reference target voltage sequence and the actual output voltage sequence are standardized respectively so that their mean is 0 and their fluctuation is the same, thereby eliminating the influence of the amplitude difference of the data itself on the matching results;

[0048] Using an enumeration method, we try shifting one set of data forward or backward by different time points. At each shift position, we calculate the degree of match between the two sets of standardized data, i.e., the cross-correlation value. We select the shift point at which the cross-correlation value reaches its maximum, and record it as the cross-correlation peak delay point, which is used to reflect whether there is a significant time lag in the control response.

[0049] The enumeration method is an exhaustive search strategy that attempts all possible time offsets within a preset range, gradually aligning two time series. This method comprehensively covers all possible alignment scenarios, ensuring that the optimal temporal correspondence between the two series is captured.

[0050] The residual lag ratio is calculated by calculating the ratio of the cross-correlation peak delay points to the total number of sampling points;

[0051] The control feedback influence coefficient is calculated based on the normalized residual deviation rate, residual misleading rate and residual lag rate. The specific acquisition steps are as follows:

[0052] ;

[0053] Where, Expressed as the control feedback influence coefficient, Expressed as the normalized residual deviation rate, Expressed as the residual misleading rate, Expressed as the residual lagged rate.

[0054] The normalized residual deviation rate is used to evaluate the relative error between the control target and the actual output. The residual misdirection rate is used to quantify the effect of the controller output on the direction of the error. The residual hysteresis rate is used to reveal whether there is a structural delay in the control response. This multi-dimensional integrated evaluation mechanism avoids reliance on a single indicator, effectively improving sensitivity and discrimination to issues such as feedback deviation, ontological misalignment, and dynamic hysteresis. It provides a more accurate basis for dynamically correcting control parameters and enhances the system's adaptive control capabilities for distributed power generation disturbances.

[0055] In this embodiment, it should be specifically explained that the steps for obtaining the behavior pattern influence coefficient are:

[0056] The number of times the power change direction is reversed is obtained according to the actual output power sequence, which is recorded as the power reversal number. The power reversal number is calculated by ratioing the total number of sampling points to obtain the reverse jump rate.

[0057] A "power change direction reversal" occurs when the output power trend changes from increasing to decreasing, or vice versa, at three consecutive sampling points. Specifically, if the power trend is increasing at one moment and then decreasing at the next, or vice versa, it is considered a reversal of direction. This phenomenon often reflects instability in system load behavior or discontinuity in control response. A greater number of reversals indicates more frequent power fluctuations, helping to measure the dynamic complexity of the operating state.

[0058] Setting the voltage threshold window ,in For the nominal voltage, obtain the number of times the output voltage value exceeds the voltage threshold window range within the detection time window, record it as the number of crossings, and calculate the ratio of the number of crossings to the total number of sampling points to get the crossing rate;

[0059] The nominal voltage is the target output voltage of a solid-state distribution transformer under rated operating conditions. It's typically predetermined by system design specifications or operating standards and serves as a benchmark for evaluating voltage deviation and stability. Comparing this with the nominal voltage effectively identifies voltage violations and reflects the system's ability to maintain voltage under load disturbances or control fluctuations.

[0060] According to the actual output power sequence and the actual output voltage sequence, the actual output power change value and the actual output voltage change value between two adjacent sampling points are calculated;

[0061] Based on the actual output power change value and the actual output voltage change value between two adjacent sampling points, the relative change amplitude of the actual output power and the relative change amplitude of the actual output voltage at each sampling point are calculated respectively. The relative change amplitude is expressed as the ratio of the change value between two consecutive sampling points to the value at the previous time point, reflecting the change intensity under the unit reference;

[0062] The actual output power relative change amplitude and the actual output voltage relative change amplitude are added together to obtain the instantaneous total fluctuation amplitude of each sampling point, and the instantaneous total fluctuation amplitude at all times is averaged to obtain the average behavioral fluctuation rate;

[0063] The behavior pattern influence coefficient is calculated based on the reverse jump rate, the boundary crossing rate, and the average behavior volatility. The specific steps for obtaining it are:

[0064] ;

[0065] Where, Expressed as the behavior pattern influence coefficient, Expressed as the reverse transition rate, Expressed as the crossing rate, Expressed as the average behavioral volatility.

[0066] The reverse hopping rate identifies frequent reversals in system power behavior, reflecting the non-stationarity of load disturbances or control switching. The overshoot rate assesses how often the voltage exceeds the safe operating range, reflecting the voltage regulation capability. The average behavior fluctuation rate quantitatively reflects the combined fluctuation amplitude of power and voltage, revealing the severity of the operating state. This method integrates three indicators: trend change, overshoot characteristics, and transient disturbances, constructing a multi-dimensional, unit-free, and physically explicit system behavior assessment mechanism. This method is conducive to improving the accuracy of identifying equivalent impedance change trends under complex operating conditions and the timeliness of control strategy adjustments.

[0067] In this embodiment, it should be specifically explained that the steps of determining whether the equivalent impedance has changed according to the equivalent impedance change index are:

[0068] The equivalent impedance change index is compared with a change threshold. If the equivalent impedance change index is greater than or equal to the change threshold, the equivalent impedance is determined to have changed; if the equivalent impedance change index is less than the change threshold, the equivalent impedance is determined to have not changed. The change threshold is determined using an adaptive threshold method, a method that dynamically adjusts the judgment threshold based on the system's operating status, aiming to improve the judgment mechanism's sensitivity and robustness to changes in magnitude under different operating conditions. In this embodiment, the change threshold is not a fixed setting, but is adjusted in real time based on the distribution characteristics of the equivalent impedance change index in historical operating data and current operating conditions (such as load level, number of connected power sources, and network topology). Specifically, statistical analysis can be performed using the mean and standard deviation of the change index within a sliding time window, or empirical coefficients can be introduced to construct a threshold correction function to generate a dynamic threshold that is time-varying and context-adaptive. This ensures that the judgment logic maintains high accuracy and anti-interference capabilities even in complex operating environments.

[0069] The controller parameter dynamic adjustment module dynamically modifies the initial control parameters according to the equivalent impedance change index if it is determined that the equivalent impedance has changed, and obtains the actual control parameters to achieve adaptive control response to the impedance change environment;

[0070] In this embodiment, it should be specifically explained that the steps for dynamically correcting the initial control parameters according to the equivalent impedance change index to obtain the actual control parameters are as follows:

[0071] A detection time window is set, and the mean voltage RMS value and the mean current RMS value within the detection time window are obtained. The ratio of the mean voltage RMS value to the mean current RMS value is calculated to obtain a current equivalent impedance estimate. The output current value is obtained in real time, and the real-time output current value is multiplied by the current equivalent impedance estimate to obtain a voltage feedforward compensation amount. It should be noted that the detection time window can be 2S or 5S. The mean voltage RMS value refers to the arithmetic mean of the voltage RMS value sequence collected from the output end of the solid-state distribution transformer, and the mean current RMS value refers to the arithmetic mean of the current RMS value sequence collected from the output current channel of the solid-state distribution transformer.

[0072] Obtaining the initial impedance value of the solid-state distribution transformer, subtracting the initial impedance value from the current equivalent impedance estimate and calculating the ratio of the current equivalent impedance estimate to the initial impedance value to obtain the impedance change rate;

[0073] If the impedance change rate is greater than 0, it is determined that the impedance has increased. The ratio of the change threshold to the equivalent impedance change index is calculated to obtain the correction factor. The specific steps for obtaining the correction factor are as follows:

[0074] ;

[0075] Where, Expressed as a correction factor, Expressed as the change threshold, Expressed as an equivalent impedance change index, when the impedance change rate is greater than 0, it indicates that the system impedance has increased, and the load's ability to absorb the power supply output has weakened, resulting in a restricted output transmission path for the controller. Maintaining the original control parameters at this time may lead to over-regulation, slow system response, or reduced stability margin. Therefore, it is necessary to appropriately reduce the control parameters and slow down the regulation to improve system robustness.

[0076] If the impedance change rate is less than 0, it is determined that the impedance has decreased. The equivalent impedance change index is calculated by ratio with the change threshold to obtain the correction factor. The specific acquisition steps are as follows:

[0077] ;

[0078] Where, Expressed as a correction factor, Expressed as the change threshold, Expressed as an equivalent impedance change index, when the impedance change rate is less than 0, it means that the system impedance is reduced, the load response is enhanced, and the controller output is more likely to cause rapid changes in the system state. If the adjustment capability is not enhanced, overshoot or dynamic error may occur. Therefore, the control parameters should be increased to improve control accuracy and response capability to achieve fast and accurate adjustment effects.

[0079] If the impedance change rate is equal to 0, it is determined that the impedance has not changed, and the initial control parameters are not corrected;

[0080] The initial control parameter is multiplied by the correction factor to obtain the actual control parameter.

[0081] In this embodiment, the "two-step impedance change determination" design strategy is adopted to balance the sensitivity of change triggering with the accuracy of control adjustment. The first step is to construct an equivalent impedance change index, integrating multiple source characteristics such as electrical response, control feedback, and behavioral patterns to comprehensively evaluate whether the system has impedance adaptation offset, providing early warning and preventing false triggering.

[0082] The second step, by calculating the impedance change rate, accurately determines the direction and magnitude of the impedance change, guiding whether to increase, decrease, or maintain the control parameter. This dual-layer judgment mechanism enables the system to both sensitively detect potential non-explicit disturbances and avoid misadjustments caused by transient fluctuations, thereby achieving highly reliable and adaptable controller adaptive optimization.

[0083] The power quality assurance and control execution module is used to adjust the output of the solid-state transformer according to the actual control parameters, realizing multi-dimensional control functions such as active power, reactive power, voltage, and frequency. It is also responsible for maintaining voltage stability in the access area, suppressing power oscillations, and guiding the direction of power flow.

[0084] In this embodiment, it should be specifically explained that the steps of adjusting the output of the solid-state transformer according to the actual control parameters are:

[0085] Based on the actual control parameters after correction and target set values, such as target output voltage, active power, and reactive power, a control reference signal is constructed, and the operating status data of the current solid-state distribution transformer is collected in real time. The operating status data includes status parameters such as output voltage, output current, active power, and reactive power, which are used for comparison and feedback in the subsequent control execution process;

[0086] The difference between the current real-time collected operating status data and the reference signal is calculated to obtain a deviation signal. The reference signal is the target output index value set during the operation of the solid-state transformer. The deviation is input into the PI controller to obtain the PI control output;

[0087] The PI controller is a classic closed-loop feedback control algorithm consisting of a proportional and an integral component. It generates adjustment commands based on the magnitude and cumulative trend of the current deviation, enabling rapid and stable tracking of the target variable. This controller is widely used in scenarios where electrical energy parameters such as voltage, current, and power are automatically adjusted, offering fast response times and minimal steady-state errors.

[0088] The PI control output is synthesized with the voltage feedforward compensation to obtain the final control instruction;

[0089] The output of the solid-state transformer is adjusted according to the final control command to achieve coordinated regulation of the active power, reactive power, output voltage, output frequency and other parameters on the transformer output side. By dynamically adjusting the PWM duty cycle and phase, the power quality on the load side is guaranteed, including voltage stabilization, frequency control, power factor improvement and other functions.

[0090] After control is executed, the transformer output state parameters are collected again to form a closed-loop feedback loop. The control parameters, deviations, adjustment instructions, and execution results of this round are also recorded for data upload and remote monitoring modules to use for historical trend analysis and control effect evaluation.

[0091] The data upload and remote monitoring module is used to upload control parameter adjustment records and real-time operation status data to the database for operation and maintenance personnel to review and intervene in strategies.

[0092] This module can upload the controller's parameter adjustment records and the real-time operating status data of the solid-state distribution transformer to a remote database for operation and maintenance personnel to view in real time, conduct historical backtracking and trend analysis, thereby achieving early warning of abnormal conditions and dynamic optimization of strategy parameters. It also supports centralized operation and maintenance, distributed control and remote diagnosis, and other functions, greatly improving the system's intelligent management level and operation and maintenance efficiency.

[0093] In this embodiment, it is necessary to specifically explain that the control method of the solid-state distribution transformer for accessing distributed power sources is improved, such as Figure 2 As shown, the following steps are included:

[0094] Step 1: Build a solid-state distribution transformer with multi-port power regulation capabilities and set the initial control parameters of the solid-state distribution transformer to support subsequent dynamic control and impedance identification functions;

[0095] Step 2: Obtain the affected data of equivalent impedance, which includes the actual output voltage sequence, the actual output current sequence, the reference target voltage sequence, the controller output sequence, and the actual output power sequence. Evaluate the affected data of equivalent impedance to obtain an equivalent impedance change index, and determine whether the equivalent impedance has changed based on the equivalent impedance change index.

[0096] Step 3: If it is determined that the equivalent impedance has changed, the initial control parameters are dynamically modified according to the equivalent impedance change index to obtain the actual control parameters, thereby achieving an adaptive control response to the impedance change environment;

[0097] Step 4: Adjust the output of the solid-state transformer according to the actual control parameters to achieve multi-dimensional control functions such as active power, reactive power, voltage, and frequency. It is also responsible for maintaining voltage stability in the access area, suppressing power oscillations, and guiding the direction of power flow.

[0098] Step 5: Upload the control parameter adjustment records and real-time operation status data to the database for operation and maintenance personnel to review and intervene in strategies.

[0099] 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 in the scope of protection of the present invention.

[0100] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. Improve the solid-state distribution transformer control system for distributed power access, characterized in that the system include: A solid-state distribution transformer construction module is used to construct a solid-state distribution transformer with multi-port power regulation capability and set initial control parameters of the solid-state distribution transformer; An equivalent impedance change evaluation module is used to obtain the affected data of equivalent impedance, which includes the actual output voltage sequence, the actual output current sequence, the reference target voltage sequence, the controller output sequence, and the actual output power sequence. An equivalent impedance change index is obtained based on the affected data of equivalent impedance, and whether the equivalent impedance has changed is determined based on the equivalent impedance change index. The controller parameter dynamic adjustment module dynamically modifies the initial control parameters according to the equivalent impedance change index to obtain the actual control parameters if it is determined that the equivalent impedance has changed. Power quality assurance and control execution module, used to adjust the solid-state transformer output according to actual control parameters; Data upload and remote monitoring module, used to upload control parameter adjustment records and real-time operation status data to the database; The steps for obtaining the equivalent impedance change index are: Set a detection time window, perform periodic sampling within the detection time window, set the sampling frequency, and calculate the total number of sampling points based on the time window and the sampling frequency. Obtain the actual output voltage sequence and actual output current sequence of the transformer within the detection time window, and evaluate the output voltage sequence and output current sequence to obtain the electrical response influence coefficient; Obtain the reference target voltage sequence and the controller output sequence within the detection time window, and evaluate the control feedback influence coefficient based on the reference target voltage sequence, the actual output voltage sequence, and the controller output sequence; Obtain the actual output power sequence within the detection time window, and evaluate the behavior pattern influence coefficient based on the actual output power sequence and the actual output voltage sequence; The electrical response influence coefficient, control feedback influence coefficient, and behavior mode influence coefficient are normalized, and the equivalent impedance change index is obtained based on the normalized electrical response influence coefficient, control feedback influence coefficient, and behavior mode influence coefficient. The specific acquisition steps are as follows: ； Where, Expressed as the equivalent impedance change index, Expressed as the normalized electrical response influence coefficient, Expressed as the normalized control feedback influence coefficient, Expressed as the normalized behavioral pattern influence coefficient, 、 、 It is expressed as the weight coefficient of the normalized electrical response influence coefficient, the weight coefficient of the normalized control feedback influence coefficient, and the weight coefficient of the normalized behavior mode influence coefficient.

2. The solid-state distribution transformer control system for improving access to distributed power sources according to claim 1, characterized in that: The steps for constructing a solid-state distribution transformer with multi-port power regulation capability are as follows: Construct a traditional dual-winding power frequency transformer, which includes a high-voltage side winding and a low-voltage side winding; The front-end converter is connected to the high-voltage side of the power frequency transformer, and the back-end converter is connected to the low-voltage side of the power frequency transformer to build a three-phase four-bridge-arm structure. The DC sides of the front-end converter and the back-end converter are connected to form a common DC link, and a low-voltage DC port is brought out to form a three-port structure with a high-voltage AC input terminal, a low-voltage AC output terminal, and a low-voltage DC output terminal, thereby constructing a solid-state distribution transformer with multi-port power regulation capability.

3. The solid-state distribution transformer control system for improving access to distributed power sources according to claim 1, characterized in that: The steps for obtaining the electrical response influence coefficient are: In the detection time window, the voltage mean, current mean, voltage standard deviation and current standard deviation in the set time window are calculated based on the actual output voltage sequence and the actual output current sequence; The voltage variation coefficient is calculated by ratioing the voltage standard deviation to the voltage mean, and the current variation coefficient is calculated by ratioing the current standard deviation to the current mean; The voltage variation coefficient and the current variation coefficient are added together and averaged to obtain the electrical response influence coefficient.

4. The solid-state distribution transformer control system for improving access to distributed power sources according to claim 1, characterized in that: The steps for obtaining the control feedback influence coefficient are: Subtracting the actual output voltage value in the actual output voltage sequence from the reference target voltage value in the reference target voltage sequence to obtain the voltage deviation value of each sampling point, calculating the ratio of the voltage deviation value to the reference target voltage value to obtain the residual deviation rate of each sampling point, and calculating the mean of the residual deviation rate of each sampling point to obtain the normalized residual deviation rate; The controller output mean is calculated based on the controller output sequence, and the ratio of the controller output mean to the voltage deviation mean is calculated and the absolute value is taken to obtain the residual misleading rate; The two sets of sampling data in the reference target voltage sequence and the actual output voltage sequence are standardized respectively; Using the enumeration method, one set of data is shifted forward or backward by different time points one by one. The matching degree between the two sets of standardized data is calculated at each shift position, that is, the cross-correlation value. The shift point number corresponding to the maximum cross-correlation value is selected and recorded as the cross-correlation peak delay point number. The residual lag ratio is calculated by calculating the ratio of the cross-correlation peak delay points to the total number of sampling points; The control feedback influence coefficient is calculated based on the normalized residual deviation rate, residual misleading rate and residual lag rate.

5. The solid-state distribution transformer control system for improving access to distributed power sources according to claim 1, characterized in that: The steps for obtaining the behavior pattern influence coefficient are: The number of times the power change direction is reversed is obtained according to the actual output power sequence, which is recorded as the power reversal number. The power reversal number is calculated by ratioing the total number of sampling points to obtain the reverse jump rate. Set the voltage threshold window and obtain the number of times the output voltage value exceeds the voltage threshold window range within the detection time window. Record it as the number of crossing the threshold. Ratio the number of crossing the threshold to the total number of sampling points to obtain the crossing rate. According to the actual output power sequence and the actual output voltage sequence, the actual output power change value and the actual output voltage change value between two adjacent sampling points are calculated; According to the actual output power change value and the actual output voltage change value between two adjacent sampling points, the relative change amplitude of the actual output power and the relative change amplitude of the actual output voltage at each sampling point are calculated respectively; The actual output power relative change amplitude and the actual output voltage relative change amplitude are added together to obtain the instantaneous total fluctuation amplitude of each sampling point, and the instantaneous total fluctuation amplitude at all times is averaged to obtain the average behavioral fluctuation rate; The behavioral pattern influence coefficient is calculated based on the reverse jump rate, the crossing rate and the average behavioral volatility.

6. The solid-state distribution transformer control system for improving access to distributed power sources according to claim 1, characterized in that: The step of determining whether the equivalent impedance has changed according to the equivalent impedance change index is as follows: The equivalent impedance change index is compared with the change threshold. If the equivalent impedance change index is greater than or equal to the change threshold, it is determined that the equivalent impedance has changed; if the equivalent impedance change index is less than the change threshold, it is determined that the equivalent impedance has not changed.

7. The solid-state distribution transformer control system for improving access to distributed power sources according to claim 1, characterized in that: The steps of dynamically correcting the initial control parameters according to the equivalent impedance change index to obtain the actual control parameters are as follows: Obtain the mean RMS voltage value and the mean RMS current value within the detection time window, calculate the ratio of the mean RMS voltage value to the mean RMS current value to obtain the current equivalent impedance estimate, obtain the output current value in real time, multiply the real-time output current value by the current equivalent impedance estimate to obtain the voltage feedforward compensation amount; Obtaining the initial impedance value of the solid-state distribution transformer, subtracting the initial impedance value from the current equivalent impedance estimate and calculating the ratio of the current equivalent impedance estimate to the initial impedance value to obtain the impedance change rate; If the impedance change rate is greater than 0, it is determined that the impedance has increased, and the ratio of the change threshold to the equivalent impedance change index is calculated; If the impedance change rate is less than 0, it is determined that the impedance has decreased, and the ratio of the equivalent impedance change index to the change threshold is calculated; If the impedance change rate is equal to 0, it is determined that the impedance has not changed, and the initial control parameters are not corrected; The initial control parameter is multiplied by the correction factor to obtain the actual control parameter.

8. The solid-state distribution transformer control system for improving access to distributed power sources according to claim 7, characterized in that: The steps of adjusting the output of the solid-state transformer according to the actual control parameters are as follows: According to the actual control parameters and the target set value, a control reference signal is constructed, and the operating status data of the current solid-state distribution transformer is collected in real time; The difference between the current real-time collected operating status data and the reference signal is calculated to obtain a deviation signal, and the deviation is input into the PI controller to obtain the PI control output; The PI control output is synthesized with the voltage feedforward compensation to obtain the final control instruction; The solid-state transformer output is adjusted according to the final control command.

9. A solid-state distribution transformer control method for improving access to distributed power sources, for implementing the solid-state distribution transformer control system for improving access to distributed power sources as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Construct a solid-state distribution transformer with multi-port power regulation capability and set the initial control parameters of the solid-state distribution transformer; Step 2: Obtain the affected data of equivalent impedance, which includes the actual output voltage sequence, the actual output current sequence, the reference target voltage sequence, the controller output sequence, and the actual output power sequence. Evaluate the affected data of equivalent impedance to obtain an equivalent impedance change index, and determine whether the equivalent impedance has changed based on the equivalent impedance change index. Step 3: If it is determined that the equivalent impedance has changed, the initial control parameters are dynamically modified according to the equivalent impedance change index to obtain the actual control parameters; Step 4: Adjust the solid-state transformer output according to the actual control parameters; Step 5: Upload the control parameter adjustment records and real-time operation status data to the database.

Images