CN115498911A - Energy storage converter prediction control method and device and storage medium - Google Patents

Energy storage converter prediction control method and device and storage medium Download PDF

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CN115498911A
CN115498911A CN202211128123.4A CN202211128123A CN115498911A CN 115498911 A CN115498911 A CN 115498911A CN 202211128123 A CN202211128123 A CN 202211128123A CN 115498911 A CN115498911 A CN 115498911A
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reference value
output voltage
energy storage
voltage reference
current
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李昱
高建波
王启武
李庆卓
贾中青
翟瑞占
张祯滨
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Laser Institute of Shandong Academy of Science
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/539—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency
    • H02M7/5395—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention relates to a predictive control method and device for an energy storage converter and a storage medium. The invention converts the measured variable into alpha-beta coordinate system through coordinate transformation and carries out delay compensation; after an original output voltage reference value set in the instruction is obtained, the error compensation reference value and the original output voltage reference value are summed to obtain a compensated corrected output voltage reference value; calculating and generating a corrected full-order variable reference value based on the corrected output voltage reference value; the measured variables comprise three-phase inductive current, three-phase capacitor voltage and three-phase output current; calculating a cost function according to the full-order variable reference value and the measured variable predicted value, and screening a switch state sequence with the minimum cost function as an optimal switch state sequence; the first element of the selected optimal sequence of switching states is applied to the current transformer via the drive circuit. The invention can effectively eliminate the output steady-state error of the energy storage converter, fully considers the coupling influence of the filter capacitor and the filter inductor, and can effectively improve the system stability.

Description

Energy storage converter prediction control method and device and storage medium
Technical Field
The invention relates to the field of energy storage converter control, in particular to a method and a device for predicting and controlling an energy storage converter and a storage medium.
Background
The vigorous development and utilization of new energy are the necessary way of the double-carbon target in China. With the continuous improvement of new energy permeability, the dynamic characteristics and the operation mode of the traditional power system are deeply changed. New energy represented by photovoltaic and wind power has natural volatility and randomness, power generation and power utilization curves are difficult to coincide in real time, and the phenomenon of imbalance of source-load exists. The energy storage system is an effective means for stabilizing the fluctuation of new energy and improving the consumption rate of the new energy. Meanwhile, when the main network fails or in remote areas which are difficult to cover by power systems such as islands, deserts and the like, the energy storage and interface converter equipment can construct stable voltage and frequency to reliably supply power for local critical loads.
The control strategy of the existing network type energy storage converter mainly adopts a proportion-resonance controller and combines an active damping technology to realize accurate tracking of output voltage. Specifically, the reference value of the output voltage is subtracted from the feedback value, the error value is sent to the proportional-resonant controller, and the output of the proportional-resonant controller is subtracted from the active damping term, so that the voltage reference value of the network-structured energy storage converter is obtained. The reference value generates a trigger signal of the power switch device through a Pulse Width Modulation (PWM) link, and drives the converter to work. In recent years, a predictive control method for a grid-type energy storage converter has been proposed. The method comprises the steps of firstly constructing a discrete domain mathematical model of the network-structured converter, and predicting the track of the output voltage at the future moment by traversing the finite switch states of the converter by combining the mathematical model. And designing a cost function according to the square sum of the difference between the output voltage reference value and the predicted value, evaluating cost function values corresponding to a limited number of switching states, defining the switching state with the minimum cost function as an optimal switching state, and applying the optimal switching state to the converter. The above process cycles through each switch state. Aiming at the main flow proportional resonant controller, the control strategy of active damping is combined, and when the control parameter is designed, the stability of the system needs to be ensured firstly. The controller parameters are typically iteratively optimized using frequency domain analysis tools (e.g., bode plots, nyquist curves, etc.) in conjunction with the stability criterion of the linear system. The digital control system of the network-forming type energy storage converter has an inherent delay link, the link causes the phase angle characteristic of the open-loop transfer function of the system to present a rapid attenuation trend, and on the other hand, the amplitude gain of an LC filter of the network-forming type energy storage converter at the resonant frequency is far higher than 0dB. Therefore, when the gain of the controller is low, the open-loop transfer function of the system can be ensured to have reasonable amplitude margin, the system is ensured to be stable, and the system is unstable due to the overlarge gain. Therefore, based on the technical scheme that the proportional resonant controller is combined with the active damping, the energy storage converter has slow dynamic response, and the output voltage distortion is large when the load suddenly increases and drops. For the prediction control of the network-building type energy storage converter, the method obviously improves the dynamic performance of the system and reduces the distortion degree of the output voltage when the load suddenly increases and suddenly decreases. However, the method has high requirements on the model precision of the controlled object, and is sensitive to external uncertain disturbances such as sampling noise, parameter drift and the like, and the factors cause output voltage to have steady-state errors and poor electric energy quality.
Disclosure of Invention
In order to solve the technical problems or at least partially solve the technical problems, the invention provides a predictive control method, a predictive control device and a storage medium for an energy storage converter.
In a first aspect, the present invention provides a predictive control method for an energy storage converter, including:
converting the measured variable into an alpha-beta coordinate system through coordinate transformation and performing delay compensation; after an original output voltage reference value set in the instruction is obtained, the error compensation reference value and the original output voltage reference value are summed to obtain a compensated corrected output voltage reference value; calculating and generating a corrected full-order variable reference value based on the corrected output voltage reference value; the measured variables comprise three-phase inductive current, three-phase capacitor voltage and three-phase output current; traversing all switch states of a two-level three-phase bridge type power circuit in the converter, calculating a measurement variable prediction value, calculating a cost function under each switch state according to a full-order variable reference value and the measurement variable prediction value, and screening a switch state sequence which enables the minimum cost function to be an optimal switch state sequence; the first element of the selected optimal sequence of switching states is applied to the current transformer via the drive circuit.
Further, after obtaining the original output voltage reference value set in the command, summing the error compensation reference value and the original output voltage reference value to obtain a compensated corrected output voltage reference value includes: acquiring an original output voltage reference value and an actual output voltage value set in the instruction, and subtracting to obtain an error signal; inputting the error signal into a proportional multi-resonance controller to calculate to obtain a compensation reference value; and summing the compensation reference value and the original output voltage reference value to obtain a compensated corrected output voltage reference value.
Furthermore, the frequency domain expression of the proportional multi-resonant controller is as follows:
Figure BDA0003849803190000031
wherein k is p Is a proportionality coefficient, k r,h (h =1,3,5,7,9,11) is a coefficient of each harmonic resonance term, ω b For damping bandwidth, ω 0 Is the fundamental frequency.
Furthermore, the coordinate transformation formula involved in transforming the measured variable into the α - β coordinate system by coordinate transformation is as follows:
Figure BDA0003849803190000032
x a 、x b and x c For measuring variables。
Still further, calculating a modified full-order variable reference value based on the modified output voltage reference value comprises: compensating time delay introduced by digital control, and calculating full-order reference values of the corrected output voltage reference value at the time of k +2 and k + 3:
Figure BDA0003849803190000033
Figure BDA0003849803190000034
wherein Δ θ = ω 0 T S Electrical angle, T, rotated for one sampling period s Is the sampling time;
according to the kirchhoff current law, the full-order reference value of the inductor current at the time of k +2 and k +3 is calculated by using the full-order reference value of the corrected output voltage reference value:
Figure BDA0003849803190000035
Figure BDA0003849803190000036
wherein, C f Is the capacitance value of the filter capacitor, and is,
Figure BDA0003849803190000037
and
Figure BDA0003849803190000038
is the load current. Typically, the load current transition is negligible over one sampling period, so the following holds:
Figure BDA0003849803190000039
Figure BDA00038498031900000310
and
Figure BDA00038498031900000311
further, the coordinate transformation formula adopted in the transformation of the measured variable into the α - β coordinate system by coordinate transformation is as follows:
Figure BDA0003849803190000041
furthermore, the calculation method for the delay compensation of the measurement variable converted into the α - β coordinate system is as follows:
Figure BDA0003849803190000042
wherein x is α ＝[i α ,v α ] T 、u α And d α Respectively measuring an alpha axis variable, an alpha axis input variable and an alpha axis load disturbance; x is the number of β ＝i β ,v β ] T 、u β And d β Respectively beta axis measurement variable, beta axis input variable and beta axis load disturbance; a is a system matrix, B is an input matrix, and D is a disturbance matrix, and the respective forms are as follows:
Figure BDA0003849803190000043
wherein L is f As inductance value of filter inductor, C f Is the capacitance value of the filter capacitor, R f Is the resistance value of a resistor connected in series with a filter inductor, T s Is the sampling time.
Further, the cost function is expressed as follows:
Figure BDA0003849803190000044
Figure BDA0003849803190000045
wherein, g is a cost function,
Figure BDA0003849803190000046
Figure BDA0003849803190000047
is a full-order variable reference value;
Figure BDA0003849803190000048
representing a quadratic form with P as the weight matrix,
Figure BDA0003849803190000051
denotes a quadratic form, g, using Q as a weight matrix c Penalty term for over-current:
Figure BDA0003849803190000052
I lim is the upper current bound; x is the number of α ，x β For calculating the predicted values of the filter capacitor voltage and the filter inductor current at the time k +2 and k + 3:
Figure BDA0003849803190000053
Figure BDA0003849803190000054
in a second aspect, the present invention provides a predictive control apparatus for an energy storage converter, including: the system comprises at least one processing unit, a storage unit, a first current acquisition unit, a second current acquisition unit, a voltage acquisition unit and a bus unit, wherein the bus unit is connected with the processing unit, the storage unit, the first current acquisition unit, the second current acquisition unit and the voltage acquisition unit, the storage unit stores at least one instruction, and the processing unit executes the instruction to realize the predictive control method of the energy storage converter.
In a third aspect, the present invention provides a storage medium for implementing a method for predictive control of an energy storage converter, the storage medium storing a computer program, the computer program, when executed by a processor connected to the energy storage converter via a driving circuit, implementing the method for predictive control of an energy storage converter.
Compared with the prior art, the technical scheme provided by the embodiment of the invention has the following advantages:
the traditional prediction control has high dependence degree on the model precision of a controlled object and poor parameter robustness, so that the output voltage of the traditional prediction control has steady-state error, the output electric energy quality of the network-structured energy storage converter is poor, and the power supply quality of a load is reduced. According to the invention, based on the error signal of the original output voltage reference value and the actual output voltage value, the compensation reference value is generated through the proportional multi-resonance controller, and the error compensation reference value and the original output voltage reference value are summed to obtain the compensated corrected output voltage reference value, so that the output steady-state error of the energy storage converter can be effectively eliminated, the power supply quality of the system is improved, and the engineering practical value is outstanding.
For an energy storage converter formed by an LC filter, the traditional prediction control only puts an error term of output voltage into a cost function, and does not consider the running state of inductive current, so that the LC filter is easy to oscillate at the inherent resonant frequency and even cause the phenomenon of system instability. In addition, the operating state of the inductor current is not considered, and overcurrent is easily caused in the dynamic regulation process of the energy storage converter, so that the power switch device exceeds the current stress and fails. According to the invention, both the voltage of the filter capacitor and the current of the filter inductor are taken into the cost function, the influence of the filter capacitor and the filter inductor is fully considered, and the stability of the system can be effectively improved. In addition, a penalty item of the current upper bound is introduced into the cost function, even if protection is executed according to the cost function during overcurrent, the rapid overcurrent protection function of the converter is realized, and the reliability of the system is improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art to obtain other drawings without inventive labor.
Fig. 1 is a schematic diagram of an energy storage converter according to an embodiment of the present invention;
fig. 2 is a flowchart of a predictive control method for an energy storage converter according to an embodiment of the present invention;
fig. 3 is a flowchart illustrating that after an original output voltage reference value set in an instruction is obtained, an error compensation reference value and the original output voltage reference value are summed to obtain a compensated corrected output voltage reference value according to an embodiment of the present invention;
FIG. 4 is a flow chart of generating a modified full-order variable reference value based on a modified output voltage reference value calculation according to an embodiment of the present invention;
fig. 5 is a schematic diagram of an energy storage converter predictive control apparatus according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a predictive control system for an energy storage converter according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a corrected output voltage reference value generating module in a predictive control system of an energy storage converter according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.
The power topology diagram of the energy storage converter is shown in figure 1 and mainly comprises an AC-side LC filter, a two-level three-phase bridge power circuit and a DC-side bus capacitor C dc And (4) forming. The AC side LC filter mainly filters high-frequency harmonic waves generated in the process of power electronic switching to obtain smooth sinusoidal output voltage. And the three-phase output end of the filter is connected to a load to supply power to the load. The two-level three-phase bridge type power circuit performs high-frequency chopping on the direct-current bus, and appropriate high-frequency square wave pulse signals are generated at the points A, B and C of the bridge arm. The DC bus capacitor is typically associated with an energy storage unit (e.g., battery E) dc ) And the high-frequency ripples superposed on the direct-current bus are filtered in parallel, and the relatively stable and smooth direct-current bus voltage is constructed.
Example 1
Referring to fig. 2, an embodiment of the present invention provides a method for controlling a prediction of an energy storage converter, including:
s100, converting the measured variable into an alpha-beta coordinate system through coordinate transformation. The measured variables include: three-phase filter inductor current i abc，k Three-phase filter capacitor voltage v abc，k And three-phase output current
Figure BDA0003849803190000081
Wherein, the transformation formula from the three-phase natural coordinate system to the alpha-beta coordinate system is as follows:
Figure BDA0003849803190000082
s200, performing time delay compensation on the measurement variable converted into the alpha-beta coordinate system:
Figure BDA0003849803190000083
wherein x is α ＝[i α ,v α ] T 、u α And d α Respectively measuring an alpha axis variable, an alpha axis input variable and an alpha axis load disturbance; x is the number of β ＝[i β ,v β ] T 、u β And d β Respectively beta axis measurement variable, beta axis input variable and beta axis load disturbance; a is a system matrix, B is an input matrix and D is a disturbance matrix, and the respective forms are as follows:
Figure BDA0003849803190000084
wherein L is f Is the inductance value of the filter inductor, C f Is the capacitance value of the filter capacitor, R f Is the resistance value of a resistor connected in series with a filter inductor, T s Is the sampling time.
And S300, after the original output voltage reference value set in the instruction is obtained, summing the error compensation reference value and the original output voltage reference value to obtain a compensated corrected output voltage reference value. And the proportional multi-resonance controller generates the error compensation reference value according to the error signal.
In the specific implementation process, referring to fig. 3, step S300 includes:
s301, acquiring the original output voltage reference value set in the command
Figure BDA0003849803190000085
And the actual output voltage value (v) after the delay compensation α,k+1 ,v β,k+1 )。
S302, outputting the original output voltage reference value
Figure BDA0003849803190000091
And the actual output voltage value (v) after time delay compensation α,k+1 ,v β,k+1 ) Difference is made to obtain an error signal (e) α,k+1 ,e β,k+1 )。
S303, converting the error signal (e) α,k+1 ,e β,k+1 ) Inputting the compensation reference value into a proportional multi-resonance controller to calculate
Figure BDA0003849803190000092
Specifically, referring to the figure, the frequency domain expression of the proportional multi-resonant controller is as follows:
Figure BDA0003849803190000093
wherein k is p Is a proportionality coefficient, k r,h (h =1,3,5,7,9,11) is a coefficient of each harmonic resonance term, ω b For damping bandwidth, ω 0 Is the fundamental frequency. The proportion and fundamental resonance parts can eliminate steady-state errors at the fundamental frequency, and resonance terms of other low-order harmonics of the multi-resonance compensator can effectively eliminate harmonic components generated by nonlinear loads, such as 3,5,7,9 and 11 harmonic components.
S304, compensating the reference value
Figure BDA0003849803190000094
With reference value of original output voltage
Figure BDA0003849803190000095
And summing to obtain a compensated corrected output voltage reference value:
Figure BDA0003849803190000096
conventional predictive control voltage-less compensators directly pass a given reference voltage to the predictive controller without modification. However, since the prediction controller has high requirements on the model accuracy and is sensitive to external uncertain disturbances such as sampling noise and parameter drift, the application of the reference voltage without correction cannot avoid the interference such as noise and drift, which may cause the output voltage to have steady-state errors. The method and the device solve the problems of output voltage steady-state error and poor electric energy quality caused by parameter drift and noise disturbance through a closed-loop feedback means.
S400, calculating and generating a corrected full-order variable reference value based on the corrected output voltage reference value;
in the specific implementation process, referring to fig. 4, S400 includes: s401, compensating the time delay introduced by digital control, and calculating the full-order reference values of the corrected output voltage reference value at the time of k +2 and k +3 as follows:
Figure BDA0003849803190000101
Figure BDA0003849803190000102
wherein Δ θ = ω 0 T s Electrical angle, T, rotated for one sampling period s Is the sampling time.
S202, according to the kirchhoff current law, calculating full-order reference values of the inductor current at the time of k +2 and k +3 by using the full-order reference values of the corrected output voltage reference values:
Figure BDA0003849803190000103
Figure BDA0003849803190000104
wherein, C f Is the capacitance value of the filter capacitor and is,
Figure BDA0003849803190000105
and
Figure BDA0003849803190000106
is the load current. Typically, the load current transition is negligible over one sampling period, so the following holds:
Figure BDA0003849803190000107
Figure BDA0003849803190000108
and
Figure BDA0003849803190000109
s500, traversing all the switch states of the two-level three-phase bridge type power circuit in the converter, and calculating the predicted values of the filter capacitor voltage and the filter inductor current at the time of k +2 and k +3 based on the corresponding switch states. The prediction equation of the filter capacitor voltage and the filter inductor current is as follows:
Figure BDA00038498031900001010
Figure BDA00038498031900001011
s600, calculating a cost function g according to the full-order variable reference value and the measured variable predicted value, and screening the switch state sequence with the minimum cost function as an optimal switch state sequence. The expression of the cost function g is as follows:
Figure BDA00038498031900001012
Figure BDA00038498031900001013
wherein, g is a cost function,
Figure BDA0003849803190000111
Figure BDA0003849803190000112
is a full-order variable reference value; x is the number of α ，x β Predicted values for the measured variables as described in S500;
Figure BDA0003849803190000113
representing a quadratic form with P as the weight matrix,
Figure BDA0003849803190000114
representing a quadratic form, g, using Q as a weight matrix c Penalty term for over-current:
Figure BDA0003849803190000115
I lim is the upper current bound. When the current exceeds the upper bound current, the cost function is always infinite, the minimum cost function cannot be screened out, and overcurrent protection is executed to protect the energy storage converter.
S700, the first element of the optimal switch state sequence selected in S600, namely (u) α,k+1 ,u β,k+1 ) Is applied to the current transformer via the drive circuit. The converter receives a driving signal of the driving circuit to control the power switch device.
And when the next sampling time comes, repeating the steps.
Example 2
Referring to fig. 5, an embodiment of the present invention provides a predictive control apparatus for an energy storage converter, including: the system comprises at least one processing unit, a storage unit, a first current acquisition unit, a second current acquisition unit, a voltage acquisition unit and a bus unit, wherein the bus unit is connected with the processing unit, the storage unit, the first current acquisition unit, the second current acquisition unit and the voltage acquisition unit, the storage unit stores at least one instruction, and the processing unit executes the instruction to realize the predictive control method of the energy storage converter. In the specific implementation process, the first current acquisition unit acquires three-phase inductive current, the second current acquisition unit acquires three-phase output current, and the voltage acquisition unit acquires three-phase capacitor voltage. The energy storage converter prediction control device is connected with a driving circuit through a control bus of a bus unit, and the driving circuit is connected with a power switch device of a two-level three-phase bridge type power circuit of the converter. The drive circuit adopts an optical coupler to carry out signal isolation.
Example 3
The embodiment of the invention provides a storage medium for realizing a predictive control method of an energy storage converter, wherein the storage medium stores a computer program, and the computer program is executed by a processor which is connected with the energy storage converter through a driving circuit to realize the predictive control method of the energy storage converter.
Example 4
Referring to fig. 6 and 7, an embodiment of the present invention provides a predictive control system for an energy storage converter, including: the correction output voltage reference value generation module is used for summing the error compensation reference value and the original output voltage reference value to obtain a compensated correction output voltage reference value after the original output voltage reference value set in the instruction is obtained; specifically, referring to fig. 7, the modified output voltage reference value generating module includes a proportional multi-resonant controller, the proportional multi-resonant controller calculates a compensation reference value according to an error signal, and a frequency domain expression of the proportional multi-resonant controller is as follows:
Figure BDA0003849803190000121
and the coordinate transformation and compensation module is used for transforming the measurement variables into an alpha-beta coordinate system and performing delay compensation. The transformation formula from the three-phase natural coordinate system to the alpha-beta coordinate system is as follows:
Figure BDA0003849803190000122
and performing time delay compensation on the measurement variable converted into the alpha-beta coordinate system:
Figure BDA0003849803190000123
wherein x is α ＝[i α ,v α ] T 、u α And d α Respectively measuring an alpha axis variable, an alpha axis input variable and an alpha axis load disturbance; x is the number of β ＝[i β ,v β ] T 、u β And d β Respectively measuring a beta axis variable, a beta axis input variable and a beta axis load disturbance; a is a system matrix, B is an input matrix and D is a disturbance matrix, and the respective forms are as follows:
Figure BDA0003849803190000131
wherein L is f As inductance value of filter inductor, C f Is the capacitance value of the filter capacitor, R f Is the resistance value of a resistor connected in series with a filter inductor, T s Is the sampling time.
A predictive control module including a full-order variable reference value generation unit, a drive signal generation unit, and a state variable prediction unit.
The full-order variable reference value generating unit is connected with the corrected output voltage reference value generating module, compensates time delay introduced by digital control, calculates full-order reference values of the corrected output voltage reference value at the time of k +2 and k +3 by using the corrected output voltage reference value, and calculates full-order reference values of the inductor current at the time of k +2 and k +3 by using the full-order reference value of the corrected output voltage reference value according to a kirchhoff current law;
and the state variable prediction unit is connected with the coordinate transformation and compensation module and predicts the measurement variables at the k +2 moment and the k +3 moment based on the measurement variables provided by the coordinate transformation and compensation module.
The driving signal generation unit is connected with the full-order variable reference value generation unit and the state variable prediction unit, the cost functions of all the switch states are calculated by using the provided full-order variable reference values and the measurement variable prediction values, the switch state sequence with the minimum cost function is screened as an optimal switch state sequence, and the first element of the selected optimal switch state sequence is applied to the converter through the driving circuit.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit may be implemented in the form of hardware, or may also be implemented in the form of a software functional unit.
The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A predictive control method for an energy storage converter is characterized by comprising the following steps:
converting the measured variable into an alpha-beta coordinate system through coordinate transformation and performing delay compensation; the measured variables comprise three-phase inductive current, three-phase capacitor voltage and three-phase output current; after an original output voltage reference value set in the instruction is obtained, the error compensation reference value and the original output voltage reference value are summed to obtain a compensated corrected output voltage reference value; calculating and generating a corrected full-order variable reference value based on the corrected output voltage reference value; traversing all switch states of a two-level three-phase bridge type power circuit in the converter, calculating a measurement variable prediction value, calculating a cost function under each switch state according to a full-order variable reference value and the measurement variable prediction value, and screening a switch state sequence which enables the minimum cost function to be an optimal switch state sequence; the first element of the selected optimal sequence of switching states is applied to the current transformer via the drive circuit.
2. The predictive control method of an energy storage converter as claimed in claim 1, wherein the step of summing the error compensation reference value with the original output voltage reference value to obtain the compensated modified output voltage reference value after obtaining the original output voltage reference value set in the command comprises: acquiring an original output voltage reference value set in the instruction and an actual output voltage value after delay compensation, and obtaining an error signal by making a difference; inputting the error signal into a proportional multi-resonance controller to calculate to obtain a compensation reference value; and summing the compensation reference value and the original output voltage reference value to obtain a compensated corrected output voltage reference value.
3. The predictive control method of an energy storage converter as claimed in claim 2, wherein the frequency domain expression of the proportional multi-resonant controller is:
Figure FDA0003849803180000011
wherein k is p Is a proportionality coefficient, k r,h (h =1,3,5,7,9,11) is a coefficient of each harmonic resonance term, ω b For damping bandwidth, ω 0 Is the fundamental frequency.
4. The predictive control method for an energy storage converter according to claim 1, characterized in that the coordinate transformation formula involved in transforming the measured variables into the α - β coordinate system by coordinate transformation is as follows:
Figure FDA0003849803180000012
x a 、x b and x c Is a measured variable.
5. The predictive control method of an energy storage converter as claimed in claim 1 wherein calculating a corrected full order delta reference based on the corrected output voltage reference comprises: compensating time delay introduced by digital control, and calculating full-order reference values of the corrected output voltage reference value at the time of k +2 and k + 3:
Figure FDA0003849803180000021
Figure FDA0003849803180000022
wherein Δ θ = ω 0 T S Electrical angle, T, rotated for one sampling period s Is the sampling time;
according to the kirchhoff current law, the full-order reference value of the inductor current at the time of k +2 and k +3 is calculated by using the full-order reference value of the corrected output voltage reference value:
Figure FDA0003849803180000023
Figure FDA0003849803180000024
wherein, C f Is the capacitance value of the filter capacitor and is,
Figure FDA0003849803180000025
and
Figure FDA0003849803180000026
is the load current. Typically, the load current transitions are negligible in one sample period, so the following holds:
Figure FDA0003849803180000027
Figure FDA0003849803180000028
and
Figure FDA0003849803180000029
6. the predictive control method for an energy storage converter as claimed in claim 1, characterized in that the coordinate transformation formula adopted when transforming the measured variables into the α - β coordinate system by coordinate transformation is:
Figure FDA00038498031800000210
7. the predictive control method of an energy storage converter according to claim 1, characterized in that the calculation method for the time delay compensation of the measured variables converted into the α - β coordinate system is:
Figure FDA0003849803180000031
wherein x is α ＝[i α ,v α ] T 、u α And d α Respectively measuring an alpha axis variable, an alpha axis input variable and an alpha axis load disturbance; x is the number of β ＝[i β ,v β ] T 、u β And d β Respectively beta axis measurement variable, beta axis input variable and beta axis load disturbance; a is a system matrix, B is an input matrix and D is a disturbance matrix, and the respective forms are as follows:
Figure FDA0003849803180000032
wherein L is f As inductance value of filter inductor, C f Is the capacitance value of the filter capacitor, R f Is the resistance value of a resistor connected in series with a filter inductor, T s Is the sampling time.
8. The predictive control method for an energy storage converter according to claim 1, characterized in that the expression of the cost function is as follows:
Figure FDA0003849803180000033
wherein, g is a cost function,
Figure FDA0003849803180000034
Figure FDA0003849803180000035
is a full-order variable reference value;
Figure FDA0003849803180000036
representing a quadratic form with P as the weight matrix,
Figure FDA0003849803180000037
representing a quadratic form, g, using Q as a weight matrix c Penalty term for overcurrent:
Figure FDA0003849803180000038
I lim is the upper current bound; x is the number of α ，x β For calculating the predicted values of the filter capacitor voltage and the filter inductor current at the time k +2 and k + 3:
Figure FDA0003849803180000041
Figure FDA0003849803180000042
9. an energy storage converter predictive control apparatus, comprising: the system comprises at least one processing unit, a storage unit, a first current acquisition unit, a second current acquisition unit, a voltage acquisition unit and a bus unit, wherein the bus unit is connected with the processing unit, the storage unit, the first current acquisition unit, the second current acquisition unit and the voltage acquisition unit, the storage unit stores at least one instruction, and the processing unit executes the instruction to realize the predictive control method of the energy storage converter according to any one of claims 1 to 8.
10. A storage medium for implementing a method for predictive control of a power converter, said storage medium storing a computer program, wherein said computer program, when executed by a processor connected to the power converter via a drive circuit, implements a method for predictive control of a power converter as claimed in any one of claims 1 to 8.
CN202211128123.4A 2022-09-16 2022-09-16 Energy storage converter prediction control method and device and storage medium Pending CN115498911A (en)

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