An alternating current and direct current dual-purpose charging pile orderly charging system and method

Abstract

This invention relates to the field of power supply and distribution technology for charging piles, specifically disclosing an orderly charging system and method for AC / DC dual-use charging piles. The system collects real-time current values, instantaneous bus voltage values, and grid connection point voltage distortion rates from AC / DC branches. It then performs time-series reconstruction of the real-time current values ​​and instantaneous bus voltage values ​​to obtain characteristic parameters representing the transient impact trend of the bus voltage. Based on these characteristic parameters, and through constructed dynamic safety boundary constraints, it generates the power regulation demand for the current control cycle. The power regulation demand is mapped to each AC / DC branch, generating regulation commands with feasible domain constraints. The regulation commands undergo time-series validity verification, eliminating invalid components that contradict the bus voltage change trend and retaining valid regulation components. Finally, the valid regulation components are superimposed onto the reference setpoints of each branch, and the superposition result is locked at the final stage based on the real-time state of the instantaneous bus voltage value to form the final execution command.

Description

Technical Field

[0001] This invention relates to the field of power supply and distribution technology for charging piles, specifically to an AC / DC dual-use charging pile orderly charging system and method. Background Technology

[0002] With the increasing popularity of electric vehicles, AC / DC integrated charging piles, which offer both AC slow charging and DC fast charging outputs, are widely used in commercial complexes, residential communities, and other settings. These charging piles typically employ a common DC bus architecture, where the AC input is rectified into DC by an AC / DC converter and connected to a common DC bus. The DC fast charging branch draws power from the bus via a DC / DC converter, while the AC slow charging branch outputs power after a DC / AC inversion, enabling power pooling and flexible allocation.

[0003] In existing AC / DC dual-use charging piles with a common DC bus architecture, when the load on multiple branches suddenly increases, the conventional control strategy only makes lagging adjustments based on the deviation between the instantaneous value of the bus voltage and the rated value, lacking prior prediction of the voltage transient impact trend; the power distribution of each branch adopts a rough approach of equal proportion or priority according to the access sequence, and the timing consistency between the adjustment command and the bus voltage drift direction is not verified after the adjustment command is generated, resulting in the adjustment amount contradicting the voltage stability requirements.

[0004] The aforementioned defects make the bus voltage prone to a sharp drop to the undervoltage protection threshold during sudden load changes, triggering the cascaded DC / DC converters to disconnect from the grid, and making it impossible to guarantee the continuous and stable operation of the charging pile group under grid voltage disturbance conditions. Summary of the Invention

[0005] The purpose of this invention is to provide an orderly charging system and method for AC / DC dual-use charging piles to solve the problems mentioned above.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] An orderly charging method for AC / DC dual-use charging piles includes the following steps:

[0008] S1 collects the real-time current value of the AC / DC branch, the instantaneous value of the bus voltage, and the voltage distortion rate at the grid connection point;

[0009] S2, performs time-series reconstruction of real-time current values ​​and instantaneous bus voltage values ​​to obtain characteristic parameters characterizing the transient impact trend of bus voltage;

[0010] S3, based on the characteristic parameters, generates the power regulation demand for the current control cycle through the constructed dynamic safety boundary constraints;

[0011] S4 maps the power regulation demand to each AC / DC branch and generates regulation commands with feasible domain constraints. The feasible domain constraints are used to limit the adjustable upper limit of the power adjustment amount of each branch.

[0012] S5, perform timing validity verification on the adjustment command, remove invalid components that contradict the trend of bus voltage change, and retain valid adjustment components;

[0013] S6 superimposes the effective adjustment component onto the reference setpoint of each branch, and simultaneously locks the superposition result at the final stage based on the real-time status of the instantaneous bus voltage value to form the final execution command.

[0014] As a further aspect of the present invention: obtaining the characteristic parameters characterizing the transient impact trend of the bus voltage specifically includes:

[0015] The instantaneous values ​​of the bus voltage at each acquisition time are constructed into a voltage sequence, and the difference between the voltage value at each time time and the mean of the voltage values ​​at the previous two times time time is extracted as the local outlier amplitude.

[0016] The voltage trajectory turning sequence is obtained based on the direction of change of voltage values ​​at adjacent time points in the voltage sequence, and the duration of continuous unidirectional turning in the turning sequence is counted as the directional inertia quantity.

[0017] The local outlier amplitude is corrected by weighting the trend inertia, and the correction results of multiple consecutive moments are accumulated over time. The accumulated value is used as a characteristic parameter of the transient impact trend.

[0018] As a further aspect of the present invention: the generation of the power regulation requirement for the current control cycle specifically includes:

[0019] By matching the magnitude of the fluctuation amplitude with the rate of change of the distortion rate, the boundary offset is obtained;

[0020] The upper limit of adjustable power for the current control cycle is calculated based on the boundary offset.

[0021] Calculate the degree of deviation of the impact trend intensity represented by the characteristic parameter from the adjustable upper limit value;

[0022] The degree of deviation is quantified to generate power regulation requirements.

[0023] As a further aspect of the present invention: obtaining the boundary offset specifically includes:

[0024] The fluctuation amplitudes are accumulated sequentially over time to obtain the cumulative fluctuation value.

[0025] The duration of the distortion rate change is counted in both positive and negative directions to obtain the positive distortion duration and the negative distortion duration.

[0026] The larger of the positive distortion duration and the negative distortion duration is taken as the dominant distortion length. The fluctuation accumulation value is corrected by the dominant distortion length in the same direction, and the corrected fluctuation accumulation value is used as the boundary offset.

[0027] As a further aspect of the present invention: the generation of adjustment instructions with feasible region constraints specifically includes:

[0028] A reference limit amplitude is constructed for each AC / DC branch, and the power regulation demand is divided into the regulation amount to be allocated according to the current carrying current ratio of each branch;

[0029] The reference limit amplitude is corrected according to the rate of change of the carrying current of each branch, and the corrected amplitude is used as the adjustable upper limit of each branch.

[0030] The adjustable upper limit of each branch is compared with the adjustment amount to be allocated. The adjustment amount to be allocated that exceeds the adjustable upper limit is reduced to the adjustable upper limit value, and the adjustment amount to be allocated that does not exceed the adjustable upper limit is retained. The adjustment vector formed after all branches are reduced and retained is used as the adjustment command.

[0031] As a further aspect of the present invention: the splitting process is as follows:

[0032] Obtain the carrying current and its changing trend of each AC / DC branch, and generate the adjustment weight of each branch based on the comparison results of the carrying current and the changing trend.

[0033] The power regulation demand is allocated to each branch as the regulation amount to be allocated according to the relative magnitude of each regulation weight;

[0034] The carrying current of each branch is superimposed with its respective adjustment amount to be allocated, and the superposition result is used as the reference limit amplitude corresponding to each branch. The reference limit amplitude corresponding to the branch with the accelerating trend of carrying current change is reduced by an equal amount.

[0035] As a further aspect of the present invention: S5 specifically includes:

[0036] Extract the current bus voltage change trend, compare the adjustment direction of each branch corresponding to the adjustment command with the change trend one by one, and mark the adjustment command that is opposite to the change trend as the component to be eliminated.

[0037] For adjustment commands that match the direction, extract their adjustment amplitude and verify whether the adjustment amplitude has a reasonable timing based on the duration of the current bus voltage change trend;

[0038] Adjustment commands with reasonable timing are retained as valid adjustment components, while other adjustment commands are discarded.

[0039] As a further aspect of the present invention: the formation of the final execution instructions specifically includes:

[0040] The effective adjustment component is algebraically superimposed with the current reference setpoint of each branch to obtain the setpoint to be verified for each branch.

[0041] Using the instantaneous values ​​of the bus voltage corresponding to each branch as the judgment benchmark, we examine one by one whether the expected voltage change trend corresponding to the given value to be verified is consistent with the transient drift direction of the bus voltage acquired in real time.

[0042] The given values ​​to be verified that are consistent in direction are marked as permission instructions, and the given values ​​to be verified that are inconsistent in direction are marked as suppression instructions and limited to the safety boundary value corresponding to the current real-time voltage. All permission instructions and the limited suppression instructions together form the final execution instruction.

[0043] An AC / DC dual-use charging pile orderly charging system includes:

[0044] The data acquisition module collects real-time current values ​​of AC and DC branches, instantaneous bus voltage values, and grid connection point voltage distortion rate.

[0045] The timing reconstruction module reconstructs the real-time current value and the instantaneous value of the bus voltage to obtain characteristic parameters that characterize the transient impact trend of the bus voltage.

[0046] The dynamic constraint module generates the power regulation demand for the current control cycle based on the characteristic parameters and the constructed dynamic safety boundary constraints.

[0047] The mapping and allocation module maps the power regulation demand to each AC / DC branch and generates regulation instructions with feasible domain constraints. The feasible domain constraints are used to limit the adjustable upper limit of the power adjustment amount of each branch.

[0048] The timing verification module verifies the timing validity of the adjustment commands, removes invalid components that contradict the trend of bus voltage change, and retains valid adjustment components.

[0049] The final-stage locking module superimposes the effective adjustment components onto the reference setpoint of each branch, and simultaneously locks the superposition result based on the real-time status of the instantaneous bus voltage value to form the final execution command.

[0050] The beneficial effects of this invention are:

[0051] (1) This invention obtains characteristic parameters that characterize the transient impact trend of bus voltage through time sequence reconstruction, and generates power regulation requirements based on dynamic safety boundary constraints, so that the power output of the charging pile can be adaptively adjusted according to the actual fluctuation state of the bus voltage, avoiding the risk of triggering the undervoltage protection of the DC / DC converter due to the bus voltage drop caused by the sudden increase in load, and improving the continuous operation capability of AC / DC charging piles under the condition of grid voltage disturbance.

[0052] (2) This invention maps the power adjustment demand to each AC / DC branch and generates adjustment commands with feasible domain constraints. It combines timing validity verification to eliminate invalid components that contradict the trend of bus voltage change, and final locking to perform final verification of the superposition result based on the real-time state of bus voltage. This limits the power adjustment amount of each branch to the range allowed by the current grid state, which helps to reduce power oscillation caused by the mismatch between the adjustment command and the actual state of the grid, and enables the power output of the charging pile group to be coordinated with the dynamic carrying capacity of the grid. Attached Figure Description

[0053] The invention will now be further described with reference to the accompanying drawings.

[0054] Figure 1 This is a flowchart of the method of the present invention;

[0055] Figure 2 This is a flowchart of the process for obtaining feature parameters in this invention;

[0056] Figure 3 This is a flowchart of the process for generating the power regulation requirement for the current control cycle in this invention.

[0057] Figure 4 This is a system block diagram of the present invention. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] Please see Figure 1 As shown, this invention is an orderly charging method for AC / DC dual-use charging piles, comprising the following steps:

[0060] S1 collects the real-time current value of the AC / DC branch, the instantaneous value of the bus voltage, and the voltage distortion rate at the grid connection point;

[0061] S2, performs time-series reconstruction of real-time current values ​​and instantaneous bus voltage values ​​to obtain characteristic parameters characterizing the transient impact trend of bus voltage;

[0062] S3, based on the characteristic parameters, generates the power regulation demand for the current control cycle through the constructed dynamic safety boundary constraints;

[0063] S4 maps the power regulation demand to each AC / DC branch and generates regulation commands with feasible domain constraints. The feasible domain constraints are used to limit the adjustable upper limit of the power adjustment amount of each branch.

[0064] S5, perform timing validity verification on the adjustment command, remove invalid components that contradict the trend of bus voltage change, and retain valid adjustment components;

[0065] S6 superimposes the effective adjustment component onto the reference setpoint of each branch, and simultaneously locks the superposition result at the final stage based on the real-time status of the instantaneous bus voltage value to form the final execution command.

[0066] In S1, the real-time current values ​​of the AC / DC branches, the instantaneous values ​​of the bus voltage, and the voltage distortion rate at the grid connection point are collected, specifically including:

[0067] Real-time current values ​​are acquired through current transformers for each AC / DC branch.

[0068] A closed-loop Hall effect current transformer is installed at the conductor of each AC branch and DC branch. The secondary output of the transformer is connected to the analog quantity acquisition channel corresponding to the branch.

[0069] During data acquisition, the current transformer converts the primary side high current into a voltage signal of 0-5 volts according to the rated transformation ratio. After being filtered by the signal conditioning circuit, the signal is sent to the analog-to-digital converter. The current instantaneous current value is read at a sampling frequency of once per millisecond and restored to the actual current value according to the transformation ratio.

[0070] The instantaneous value of the bus voltage is acquired by a resistor divider connected in parallel between the positive and negative terminals of the DC bus.

[0071] The voltage divider is composed of high-precision metal film resistors connected in series, with a voltage division ratio set to 1000:1. A voltage follower is connected to the output terminal to isolate the load from the influence of the voltage divider.

[0072] The analog voltage signal output by the follower is low-pass filtered and then sent to the same analog-to-digital converter synchronously with the current value. It is sampled once every millisecond, and the instantaneous value of the bus voltage is calculated based on the voltage division ratio and the sampled value.

[0073] The voltage distortion rate at the grid connection point is acquired through a power quality monitoring terminal.

[0074] The terminal is installed in parallel on the low-voltage side bus of the distribution transformer to which the charging pile is connected. It contains a voltage transformer and a digital signal processing unit, which can synchronously sample the grid voltage waveform at 256 points per cycle and decompose the effective values ​​of the fundamental voltage and each harmonic voltage through fast Fourier transform.

[0075] The terminal uses the ratio of the total effective value of harmonics to the effective value of the fundamental frequency as the total harmonic distortion rate. It sends the distortion rate value outward via the fieldbus at a cycle of once every 200 milliseconds. The main control unit receives the value and stores it in the data buffer of the current control cycle.

[0076] All three acquisition methods use industrial-grade standard equipment, and the sampling timing is synchronously triggered by the same clock source to ensure that the acquisition time of each data is consistent, providing basic data for time alignment for subsequent timing reconstruction.

[0077] Please see Figure 2 As shown, in S2, the real-time current value and the instantaneous value of the bus voltage are reconstructed in time sequence to obtain characteristic parameters characterizing the transient impact trend of the bus voltage, specifically including:

[0078] The voltage sequence is constructed and the local outlier amplitude is extracted by arranging the instantaneous bus voltage values ​​collected in step S1 in chronological order of collection time to form a voltage sequence.

[0079] For each time point in the sequence other than the first two, take the voltage value of the first time point before that time point and the voltage value of the second time point before that time point, add the two together and divide by two to obtain the average voltage value of the first two time points.

[0080] Then, subtract the average voltage value from the current voltage value and take the absolute value of the result as the local outlier amplitude at that moment. This amplitude represents the degree of abnormal deviation of the current voltage from the recent voltage level.

[0081] The voltage trajectory turning sequence is obtained and the trend inertia is statistically analyzed. The voltage values ​​of each two adjacent moments in the voltage sequence are compared. If the voltage value of the later moment is greater than or equal to the voltage value of the previous moment, the turning direction of the adjacent pair is marked as the upward direction; if the voltage value of the later moment is less than the voltage value of the previous moment, it is marked as the downward direction.

[0082] Arrange all adjacent pairs of turning directions in chronological order to form a voltage trajectory turning sequence.

[0083] The duration of each consecutive segment with the same turning direction in the turning sequence is counted. Specifically, the counting starts from the first direction of the turning sequence. When the direction changes, the current counting ends and a new counting begins. The duration of each consecutive segment with the same turning direction is recorded as the directional inertia value corresponding to that segment. This inertia value is expressed in units of sampling periods and reflects the strength of the continuous change of the bus voltage in the current direction.

[0084] The characteristic parameters are obtained by multiplying the local outlier amplitude at each moment by the directional inertia corresponding to the previous moment to obtain the weighted correction value at that moment, where the directional inertia of the previous moment is the duration of the most recent continuous unidirectional turning before that moment.

[0085] Five consecutive weighted correction values ​​are taken, and the five correction values ​​are added together. The cumulative value is used as a characteristic parameter of the transient impact trend. This characteristic parameter is used to characterize the strength of the impact of the current impact on the bus voltage in the future period.

[0086] Please see Figure 3 As shown, in S3, based on the characteristic parameters and through the constructed dynamic safety boundary constraints, the power regulation demand for the current control cycle is generated, specifically including:

[0087] To obtain the fluctuation amplitude and distortion rate change rate, the instantaneous value of the bus voltage collected in step S1 is used to obtain the voltage fluctuation amount at each time by taking the absolute value of the difference between two adjacent instantaneous voltage values ​​in chronological order. The arithmetic mean of the ten consecutive voltage fluctuations before the current time is taken as the fluctuation amplitude at the current time. This fluctuation amplitude reflects the average oscillation degree of the instantaneous voltage value in the recent period.

[0088] The voltage distortion rate at the grid connection point collected in step S1 is used to obtain the distortion rate change rate at the current moment by taking the difference between the distortion rate at the current moment and the distortion rate at the previous moment in chronological order. When the change rate is positive, it indicates that the degree of voltage harmonic pollution is aggravated, and when it is negative, it indicates that the degree of harmonic pollution is reduced.

[0089] The cumulative fluctuation value is obtained by arranging the fluctuation amplitudes of the twenty consecutive sampling times before the current time in chronological order, and taking the arithmetic sum of these twenty fluctuation amplitudes as the cumulative fluctuation value. This cumulative value represents the overall accumulation level of voltage disturbance energy in the recent period, and its value increases as the voltage continues to fluctuate.

[0090] To obtain the positive and negative distortion duration lengths, the distortion rate change rates of the thirty consecutive sampling times preceding the current time are extracted. From these thirty values, the change rates with zero values ​​are excluded, and only the non-zero change rates are retained.

[0091] Starting from the earliest moment, rates of change with the same sign are grouped together. Whenever the sign of the rate of change changes, a new group is started, thus obtaining a continuous sequence of several groups of rates of change with the same sign.

[0092] Select all sequences with positive signs, and record the number of sequences containing the most rates of change as the positive distortion duration; select all sequences with negative signs, and record the number of sequences containing the most rates of change as the negative distortion duration.

[0093] The selection of the dominant distortion length and the calculation of the boundary offset involve comparing the values ​​of the positive and negative distortion continuation lengths, and taking the larger of the two as the dominant distortion length. The sign direction corresponding to this dominant distortion length is the dominant direction of the current distortion change. If the dominant distortion direction is positive, the cumulative fluctuation value is multiplied by an attenuation coefficient of 0.7, and the product is used as the boundary offset; if the dominant distortion direction is negative, the cumulative fluctuation value is multiplied by an attenuation coefficient of 0.5, and the product is used as the boundary offset; if the two lengths are equal, the cumulative fluctuation value is multiplied by an attenuation coefficient of 0.6 as the boundary offset.

[0094] The attenuation coefficient is set based on the following: the continuation of distortion in the positive direction indicates that harmonics are aggravated and pose a greater threat to voltage stability than in the negative direction. Therefore, a larger attenuation coefficient is used to retain more safety margins. The continuation of distortion in the negative direction indicates that harmonics are slowed down. A smaller attenuation coefficient can be used to shrink the safety margins accordingly.

[0095] The attenuation coefficients of 0.7, 0.5, and 0.6 are derived from statistical regression analysis of measured data from substations.

[0096] The power adjustable upper limit of the current control cycle is calculated by taking the sum of the fluctuation amplitude and the boundary offset at the current moment as the reference value of the dynamic safety boundary.

[0097] Divide the rated power of the distribution transformer where the charging pile is located by the benchmark value, and the resulting quotient is recorded as the adjustable upper limit of power. This adjustable upper limit represents the maximum power that the charging pile is allowed to output under the combined conditions of current voltage fluctuations and harmonic distortion.

[0098] The calculation of the degree of deviation of the impact trend intensity from the adjustable upper limit value is obtained by subtracting the adjustable upper limit value of the power from the characteristic parameter value obtained in step S2, and obtaining the parameter difference value. This difference value represents the degree to which the current transient impact trend exceeds the safe bearing capacity.

[0099] Divide the parameter difference by the adjustable upper limit of power to obtain the relative deviation rate. This ratio is the degree of deviation of the impact trend intensity from the adjustable upper limit. When the deviation is positive, it indicates that the impact trend has approached or exceeded the safety boundary.

[0100] The power regulation demand is generated by multiplying the deviation degree by the current control cycle duration (0.01 seconds), adding the power regulation demand value of the previous control cycle by 0.8, and obtaining the value as the power regulation demand of the current control cycle.

[0101] The initial value of the power regulation requirement in the previous control cycle is zero.

[0102] In S4, power regulation requirements are mapped to each AC / DC branch, generating regulation commands with feasible region constraints. These constraints limit the adjustable upper limit of power adjustment for each branch, specifically including:

[0103] The carrying current and its changing trend are obtained by directly taking the real-time current value of the corresponding AC / DC branch collected in step S1; the real-time current values ​​of each AC / DC branch collected in step S1 are arranged in chronological order, and the real-time current values ​​of five consecutive sampling times before the current time are taken, and a straight line is fitted by the least squares method, and the slope value of the straight line is taken as the changing trend of the carrying current of the branch.

[0104] If the slope is positive, it indicates that the current carried by the branch is in a state of accelerated growth; if it is negative, it indicates that the current carried by the branch is in a state of deceleration.

[0105] The generation of the regulation weights for each branch is based on the assumption that the total number of AC / DC branches participating in the current regulation process is . Article, take the first one. The current carrying capacity of each branch circuit is denoted as . The trend of its current carrying capacity is denoted as .

[0106] The maximum current carried by all currently online branches is denoted as . The arithmetic mean of the changing trends of the current carried by all branches is denoted as . . No. Adjustment weight of branch Calculate using the following formula: ;

[0107] in, For the first The current carrying capacity of each branch circuit The maximum value of the current carried by all online branches. For the first The trend of current carrying capacity variation in each branch circuit. This is the arithmetic mean of the changing trends of the current carried by all branches. This is the zero-prevention correction term in the denominator. In the formula, branches with larger current carrying values ​​and stronger changing trends receive higher adjustment weights to reflect the sensitivity of the branch to power regulation at the current moment.

[0108] The calculation of the adjustment amount to be allocated is based on the power adjustment demand obtained in step S3, denoted as... The adjustment weights of each branch participating in the adjustment to Add them together to get the total weight.

[0109] For the A branch road, its adjustment weight Divide by the sum of the weights to obtain the regulation ratio that the branch should undertake, and then multiply the regulation ratio by the power regulation demand. The product result is used as the first The amount of adjustment to be allocated for each branch.

[0110] The construction of the reference limit amplitude for each branch is for the first... A branch circuit, its current carrying value The summation result is recorded as the reference limit amplitude and is added to the adjustment amount to be allocated to this branch obtained in step S4. Determine the trend of current carrying capacity changes in each branch. ,like If the current is greater than zero (i.e., the current carrying capacity is accelerating), then the reference limit amplitude of this branch will be set. The reduction is performed by an equal amount based on the acceleration value, specifically: take the branch. The absolute value and all positive trend branches The ratio of the sum of absolute values ​​is multiplied by the reference limit amplitude. The product is used as a reduction factor. The final reference limit amplitude for this branch is obtained by subtracting this reduction amount. If... If the value is less than or equal to zero, the reference limit amplitude of the branch remains unchanged.

[0111] The adjustment of the adjustable upper limit of each branch, for the first For each branch, the rate of change of the current carrying capacity of that branch at the current moment is taken. Specifically, the difference between the current value at the current moment and the current value at the previous moment is divided by the sampling interval (0.001 seconds) as the rate of change of the current carrying capacity.

[0112] Multiply the absolute value of the rate of change by 0.2 and then add the baseline limit amplitude. The corrected amplitude is then used as the adjustable upper limit for that branch. .

[0113] The coefficient 0.2 is derived from the measured calibration of the temperature rise characteristics of the power devices in the charging pile, and is used to convert the short-term impact of the current change rate on the power carrying capacity into a power amplitude correction amount.

[0114] The generation of adjustment instructions, for the first For each branch, the adjustment amount to be allocated is compared with the adjustable upper limit of that branch. Compare them.

[0115] If the adjustment amount to be allocated is less than or equal to If the adjustment to be allocated is greater than the final adjustment for that branch, then the adjustment to be allocated will be retained; if the adjustment to be allocated is greater than the final adjustment for that branch, then the adjustment to be allocated will be retained. Then As the final adjustment amount for this branch, it reduces the excess portion.

[0116] Arrange the final adjustment values ​​of all branches in order of branch number, and the resulting numerical sequence is the adjustment command.

[0117] The calculation formula for the final adjustment amount retained by each branch is for the first... The branch circuit, its final adjustment amount Determine according to the following formula: ;

[0118] in, For the first The adjustment amount to be allocated for each branch, For the first The adjustable upper limit for each branch. This formula means that if the adjustment amount to be allocated does not exceed the adjustable upper limit, it will be retained directly; if it exceeds the upper limit, the adjustable upper limit will be used as the final adjustment amount. The final adjustment amount for each branch will be... to Arranged in order of branch number, forming an adjustment vector.

[0119] In S5, the timing validity of the regulation commands is checked, invalid components that contradict the trend of bus voltage change are removed, and valid regulation components are retained. Specifically, this includes:

[0120] To extract the bus voltage change trend, the instantaneous bus voltage value collected in step S1 is taken, and the voltage value at the current moment is subtracted from the voltage value at the previous moment. If the difference is positive, the current bus voltage change trend is marked as an upward trend; if the difference is negative, it is marked as a downward trend; if the difference is zero, it is marked as a flat trend.

[0121] The adjustment direction is obtained and compared. For the final adjustment amount of each branch contained in the adjustment command generated in step S4, the positive or negative sign of the final adjustment amount of each branch is determined one by one.

[0122] If the final adjustment value of a certain branch is positive, then the adjustment direction of that branch is marked as positive, indicating that the output power of that branch needs to be increased.

[0123] If the value is negative, it is marked as negative, indicating that the output power of the branch needs to be reduced; if the value is zero, it is marked as zero, indicating that the branch does not need to be adjusted.

[0124] The adjustment direction of each branch is compared with the current bus voltage change trend one by one: when the bus voltage change trend is upward, the final adjustment amount marked as positive is consistent with the direction, and the final adjustment amount marked as negative is contrary to the direction; when the bus voltage change trend is downward, the final adjustment amount marked as negative is consistent with the direction, and the final adjustment amount marked as positive is contrary to the direction; when the bus voltage change trend is flat, all adjustment directions are marked as consistent with the direction.

[0125] Mark the final adjustment values ​​of branches with conflicting directions as components to be eliminated, and retain the final adjustment values ​​of branches with matching directions for the next judgment step.

[0126] Extracting the adjustment amplitude of the final adjustment amount for direction matching: For each branch's final adjustment amount retained after direction comparison, take the absolute value of its value as the adjustment amplitude corresponding to that branch. This adjustment amplitude represents the magnitude of the power adjustment to be performed on that branch.

[0127] The length of the bus voltage change trend is obtained based on the trend inertia value obtained in step S2. The trend inertia value corresponding to the current moment is taken as the length of the bus voltage change trend. The length of the trend is expressed in units of sampling periods, which represents the number of sampling times in which the current bus voltage changes continuously in the same direction.

[0128] The determination of the timing rationality of the adjustment amplitude is based on the duration of the bus voltage change trend. Specifically, if the duration is greater than or equal to five sampling periods, the adjustment amplitude is compared with a judgment interval. The lower limit of the judgment interval is zero, and the upper limit of the adjustment is the product of the duration value and 0.1. If the adjustment amplitude is within the judgment interval, the final adjustment amount is marked as having timing rationality.

[0129] If the duration is less than five sampling periods, the adjustment amplitude is compared with another judgment interval, the lower limit of which is zero and the upper limit of which is the product of the duration value and 0.05. If the adjustment amplitude is within the judgment interval, the final adjustment amount is marked as having timing rationality.

[0130] The coefficients 0.1 and 0.05 correspond to the allowable degree of adjustment amplitude under long-term continuous trend and short-term emerging trend, respectively, and their values ​​are derived from the statistical calibration of actual operating data of charging stations.

[0131] The retention of effective adjustment components involves retaining the final adjustment amounts of each branch that have been verified and marked as having reasonable timing, and removing the components marked as to be removed as well as the final adjustment amounts that do not have reasonable timing.

[0132] A new adjustment vector is formed from all the retained effective adjustment components, and this adjustment vector is used as the input for superposition in step S6.

[0133] In S6, the effective adjustment components are superimposed onto the reference setpoints of each branch. Simultaneously, the superposition result is locked at the final stage based on the real-time status of the instantaneous bus voltage, forming the final execution command, which specifically includes:

[0134] To obtain the given value to be verified, the effective adjustment components of each branch retained in step S5 are algebraically superimposed with the reference given values ​​of each branch. Specifically, the reference given value of each branch is the power output target value that has been sent to the execution end of each branch at the end of the previous control cycle, and this value is stored in the holding register of the main control unit.

[0135] For each branch, the current reference setpoint of the branch is added to the effective adjustment component corresponding to the branch in step S5. If the effective adjustment component is positive, the reference setpoint is increased; if it is negative, the reference setpoint is decreased; if it is zero, it remains unchanged. The value obtained after superposition is used as the setpoint to be verified for the branch.

[0136] The bus voltage reference value is obtained by taking the instantaneous bus voltage value collected in step S1 and using it as the common bus voltage reference value for each branch.

[0137] Since all AC and DC branches are connected to the same DC bus, the instantaneous bus voltage values ​​corresponding to each branch are the same, which are all the instantaneous bus voltage values ​​collected at the current moment.

[0138] The calculation of the expected voltage change trend corresponding to the given value to be verified involves subtracting the current reference given value of the branch from the given value to be verified for each branch to obtain the change in the given value.

[0139] The sign of the change in the given value is used as the expected direction of power adjustment, where a positive change in the given value indicates an expected adjustment toward increasing power, and a negative change in the given value indicates an expected adjustment toward decreasing power.

[0140] Divide the change in the given value by the sampling interval (0.001 seconds) to obtain the expected power adjustment rate.

[0141] Multiply the expected power adjustment rate by the bus capacitance value (in farads) and then divide by the instantaneous bus voltage value to obtain the expected voltage change rate. Take the sign of this change rate as the expected voltage change trend.

[0142] To obtain the transient drift direction of the bus voltage, take the instantaneous value of the bus voltage at the current moment and the instantaneous value of the bus voltage at the previous moment collected in step S1, calculate the difference between the two, and use the sign of the difference as the transient drift direction of the bus voltage. When the difference is positive, it is marked as positive drift, and when the difference is negative, it is marked as negative drift.

[0143] The direction consistency test compares the expected voltage change trend of each branch with the transient drift direction of the bus voltage corresponding to that branch one by one: if the expected voltage change trend is positive and the transient drift direction of the bus voltage is also positive, then it is determined that the direction is consistent; if both are negative, it is also determined that the direction is consistent; if one is positive and the other is negative, then it is determined that the direction is inconsistent.

[0144] The marking of the permission instruction and the limiting of the instruction to be suppressed will mark the given value to be verified that is consistent with the direction as the permission instruction, and the permission instruction will be directly used as the final execution value of the branch.

[0145] The given value to be verified that is determined to be inconsistent in direction is marked as a suppression command. The suppression command is then subjected to amplitude limiting processing, specifically: the smaller of the rated value of the bus voltage (800 volts) and the instantaneous value of the bus voltage at the current moment is taken, and the smaller value is divided by two to obtain the safety boundary value; the value of the suppression command is compared with the safety boundary value. If the suppression command is greater than the safety boundary value, its value is changed to the safety boundary value; if the suppression command is less than or equal to the safety boundary value, its original value is kept unchanged.

[0146] The final execution instruction is formed by keeping the original values ​​of the permitted instructions in all branches, replacing the original suppressed instructions with the suppressed instructions in all branches after the limiting process, and using the instruction set formed after the above marking and limiting process of all branches as the final execution instruction. This final execution instruction is issued to the power execution terminal of each branch.

[0147] Please see Figure 4 As shown, an AC / DC dual-use charging pile orderly charging system includes:

[0148] The data acquisition module collects real-time current values ​​of AC and DC branches, instantaneous bus voltage values, and grid connection point voltage distortion rate.

[0149] The timing reconstruction module reconstructs the real-time current value and the instantaneous value of the bus voltage to obtain characteristic parameters that characterize the transient impact trend of the bus voltage.

[0150] The dynamic constraint module generates the power regulation demand for the current control cycle based on the characteristic parameters and the constructed dynamic safety boundary constraints.

[0151] The mapping and allocation module maps the power regulation demand to each AC / DC branch and generates regulation instructions with feasible domain constraints. The feasible domain constraints are used to limit the adjustable upper limit of the power adjustment amount of each branch.

[0152] The timing verification module verifies the timing validity of the adjustment commands, removes invalid components that contradict the trend of bus voltage change, and retains valid adjustment components.

[0153] The final-stage locking module superimposes the effective adjustment components onto the reference setpoint of each branch, and simultaneously locks the superposition result based on the real-time status of the instantaneous bus voltage value to form the final execution command.

[0154] The working principle of this invention is as follows: Real-time current values ​​of AC / DC branches, instantaneous bus voltage values, and grid connection point voltage distortion rates are collected; the real-time current values ​​and instantaneous bus voltage values ​​are reconstructed in time sequence to obtain characteristic parameters representing the transient impact trend of the bus voltage; based on the characteristic parameters, power regulation requirements for the current control cycle are generated through constructed dynamic safety boundary constraints; the power regulation requirements are mapped to each AC / DC branch to generate regulation commands with feasible domain constraints; the timing validity of the regulation commands is verified, eliminating invalid components that contradict the bus voltage change trend and retaining valid regulation components; the valid regulation components are superimposed onto the reference setpoint of each branch, and the superposition result is locked at the final stage based on the real-time state of the instantaneous bus voltage value to form the final execution command. This invention enables orderly charging control of AC / DC charging piles.

[0155] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for orderly charging of a charging pile that can use both AC and DC power, characterized in that, Includes the following steps: S1 collects the real-time current value of the AC / DC branch, the instantaneous value of the bus voltage, and the voltage distortion rate at the grid connection point; S2, performs time-series reconstruction of real-time current values ​​and instantaneous bus voltage values ​​to obtain characteristic parameters characterizing the transient impact trend of bus voltage; S3, based on the characteristic parameters, generates the power regulation demand for the current control cycle through the constructed dynamic safety boundary constraints; S4 maps the power regulation demand to each AC / DC branch and generates regulation commands with feasible region constraints. The feasible region constraints are used to limit the upper limit of the power adjustment amount of each branch. S5, perform timing validity verification on the adjustment command, remove invalid components that contradict the trend of bus voltage change, and retain valid adjustment components; S6 superimposes the effective adjustment component onto the reference setpoint of each branch, and simultaneously locks the superposition result at the final stage based on the real-time status of the instantaneous bus voltage value to form the final execution command.

2. The orderly charging method for a dual-use AC / DC charging pile according to claim 1, characterized in that, The specific features obtained to characterize the transient impact trend of the bus voltage include: The instantaneous values ​​of the bus voltage at each acquisition time are constructed into a voltage sequence, and the difference between the voltage value at each time time and the mean of the voltage values ​​at the previous two times time time is extracted as the local outlier amplitude. The voltage trajectory turning sequence is obtained based on the direction of change of voltage values ​​at adjacent time points in the voltage sequence, and the duration of continuous unidirectional turning in the turning sequence is counted as the directional inertia quantity. The local outlier amplitude is corrected by weighting the trend inertia, and the correction results of multiple consecutive moments are accumulated over time. The accumulated value is used as a characteristic parameter of the transient impact trend.

3. The orderly charging method for a dual-use AC / DC charging pile according to claim 1, characterized in that, The generation of the power regulation requirement for the current control cycle specifically includes: By matching the magnitude of the fluctuation amplitude with the rate of change of the distortion rate, the boundary offset is obtained; The upper limit of adjustable power for the current control cycle is calculated based on the boundary offset. Calculate the degree of deviation of the impact trend intensity represented by the characteristic parameter from the adjustable upper limit value; The degree of deviation is quantified to generate power regulation requirements.

4. The orderly charging method for a dual-use AC / DC charging pile according to claim 3, characterized in that, The acquisition of the boundary offset specifically includes: The fluctuation amplitudes are accumulated sequentially over time to obtain the cumulative fluctuation value. The duration of the distortion rate change is counted in both positive and negative directions to obtain the positive distortion duration and the negative distortion duration. The larger of the positive distortion duration and the negative distortion duration is taken as the dominant distortion length. The fluctuation accumulation value is corrected by the dominant distortion length in the same direction, and the corrected fluctuation accumulation value is used as the boundary offset.

5. The orderly charging method for a dual-use AC / DC charging pile according to claim 1, characterized in that, The generation of adjustment instructions with feasible region constraints specifically includes: A reference limit amplitude is constructed for each AC / DC branch, and the power regulation demand is divided into the regulation amount to be allocated according to the current carrying current ratio of each branch; The reference limit amplitude is corrected according to the rate of change of the carrying current of each branch, and the corrected amplitude is used as the adjustable upper limit of each branch. The adjustable upper limit of each branch is compared with the adjustment amount to be allocated. The adjustment amount to be allocated that exceeds the adjustable upper limit is reduced to the adjustable upper limit value, and the adjustment amount to be allocated that does not exceed the adjustable upper limit is retained. The adjustment vector formed after all branches are reduced and retained is used as the adjustment command.

6. The orderly charging method for a dual-use AC / DC charging pile according to claim 5, characterized in that, The splitting process is as follows: Obtain the carrying current and its changing trend of each AC / DC branch, and generate the adjustment weight of each branch based on the comparison results of the carrying current and the changing trend. The power regulation demand is allocated to each branch as the regulation amount to be allocated according to the relative magnitude of each regulation weight; The carrying current of each branch is superimposed with its respective adjustment amount to be allocated, and the superposition result is used as the reference limit amplitude corresponding to each branch. The reference limit amplitude corresponding to the branch with the accelerating trend of carrying current change is reduced by an equal amount.

7. The orderly charging method for a dual-use AC / DC charging pile according to claim 1, characterized in that, S5 specifically includes: Extract the current bus voltage change trend, compare the adjustment direction of each branch corresponding to the adjustment command with the change trend one by one, and mark the adjustment command that is opposite to the change trend as the component to be eliminated. For adjustment commands that match the direction, extract their adjustment amplitude and verify whether the adjustment amplitude has a reasonable timing based on the duration of the current bus voltage change trend; Adjustment commands with reasonable timing are retained as valid adjustment components, while other adjustment commands are discarded.

8. The orderly charging method for a dual-use AC / DC charging pile according to claim 1, characterized in that, The process of forming the final execution instruction specifically includes: The effective adjustment component is algebraically superimposed with the current reference setpoint of each branch to obtain the setpoint to be verified for each branch. Using the instantaneous values ​​of the bus voltage corresponding to each branch as the judgment benchmark, we examine one by one whether the expected voltage change trend corresponding to the given value to be verified is consistent with the transient drift direction of the bus voltage acquired in real time. The given values ​​to be verified that are consistent in direction are marked as permission instructions, and the given values ​​to be verified that are inconsistent in direction are marked as suppression instructions and limited to the safety boundary value corresponding to the current real-time voltage. All permission instructions and the limited suppression instructions together form the final execution instruction.

9. An AC / DC dual-use charging pile orderly charging system, characterized in that, A method for orderly charging of an AC / DC dual-use charging pile according to any one of claims 1-8 includes: The data acquisition module collects real-time current values ​​of AC and DC branches, instantaneous bus voltage values, and grid connection point voltage distortion rate. The timing reconstruction module reconstructs the real-time current value and the instantaneous value of the bus voltage to obtain characteristic parameters that characterize the transient impact trend of the bus voltage. The dynamic constraint module generates the power regulation demand for the current control cycle based on the characteristic parameters and the constructed dynamic safety boundary constraints. The mapping and allocation module maps the power regulation demand to each AC / DC branch and generates regulation instructions with feasible domain constraints. The feasible domain constraints are used to limit the adjustable upper limit of the power adjustment amount of each branch. The timing verification module verifies the timing validity of the adjustment commands, removes invalid components that contradict the trend of bus voltage change, and retains valid adjustment components. The final-stage locking module superimposes the effective adjustment components onto the reference setpoint of each branch, and simultaneously locks the superposition result based on the real-time status of the instantaneous bus voltage value to form the final execution command.

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