CN116231619A - Distributed power supply and EV load access micro-grid disturbance control method and device - Google Patents
Distributed power supply and EV load access micro-grid disturbance control method and device Download PDFInfo
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- CN116231619A CN116231619A CN202310483294.7A CN202310483294A CN116231619A CN 116231619 A CN116231619 A CN 116231619A CN 202310483294 A CN202310483294 A CN 202310483294A CN 116231619 A CN116231619 A CN 116231619A
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- 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
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/14—Balancing the load in a network
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- 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
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/10—Parallel operation of dc sources
- H02J1/102—Parallel operation of dc sources being switching converters
-
- 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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33573—Full-bridge at primary side of an isolation transformer
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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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33584—Bidirectional converters
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- Power Engineering (AREA)
- Electric Propulsion And Braking For Vehicles (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention belongs to the technical field of direct current transformers, and provides a disturbance control method and a disturbance control device for a distributed power supply and EV load access micro-grid, wherein the method comprises the following steps: constructing a super local model ULM of the double active full bridge converter DAB; setting a ULM controller based on a super local model ULM; setting a sliding mode observer SMO based on the ULM controller; and introducing a sliding mode observer SMO to the construction of the ULM controller, and constructing a super local model control model to control DAB in the distributed power supply and the electric automobile load to be stably connected in a grid. The invention combines the characteristic of good observation performance of SMO, adopts SMO to estimate the unknown item in ULM, thereby finally controlling and achieving good stability and robustness of DC bus voltage under large disturbance.
Description
Technical Field
The invention belongs to the technical field of direct-current transformers, and particularly relates to a disturbance control method and device for a distributed power supply and EV load access micro-grid.
Background
The new energy power generation is connected into the power system in the form of a direct current micro-grid, and is an important way for the utilization of the new energy power generation. However, as the new energy source generates power and the random load is largely connected to the direct-current micro-grid, uncertain factors such as intermittence, discreteness, fluctuation and the like on the two sides of the source load can generate larger disturbance, so that the stability of the direct-current micro-grid is challenged, and the stable operation of the grid is further influenced.
The DC/DC converter is key equipment for connecting direct current source load equipment such as new energy power generation, an energy storage device, an electric automobile and the like to a direct current micro-grid, and plays an important role in maintaining the voltage stability of a direct current bus and the stable operation of the micro-grid. A Dual-active full-bridge converter (DAB) is an isolated bidirectional DC/DC converter, and is widely used in the energy exchange fields such as smart grids, electric/hybrid cars, and interfaces between DC ports. Compared with other DC/DC converters, DAB has the advantages of high efficiency, strong reliability, large voltage regulation range, high power density, no voltage switch and the like, and is applied to the electric power fields of electric automobiles, renewable energy sources, energy storage systems and the like on a large scale.
The new energy power generation, the energy storage device, the electric automobile and the like are connected into a direct current micro-grid through DAB, the direct current micro-grid becomes a typical nonlinear system, and the dynamic response speed is reduced by adopting a linear control method and distorting the output voltage waveform if the output voltage waveform is subjected to larger disturbance.
Aiming at the large disturbance problem caused by new energy power generation and random load large-scale access, a distributed power supply and EV load access micro-grid disturbance control method and device are required to be arranged so as to solve the technical problem.
Disclosure of Invention
Aiming at the technical problems, the invention provides a distributed power supply and EV load access micro-grid disturbance control method, which comprises the following steps:
constructing a super local model ULM of the double active full bridge converter DAB;
setting a ULM controller based on a super local model ULM;
setting a sliding mode observer SMO based on the ULM controller;
and introducing a sliding mode observer SMO to the construction of the ULM controller, and constructing a super local model control model to control DAB in the distributed power supply and the electric automobile load to be stably connected in a grid.
In some embodiments, the setting ULM controller includes:
setting a control law of the ULM controller, wherein the control law is determined by the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing the input of DAB, < >>
Indicating proportional gain, +.>
Represents the output voltage of DAB->
Is used for the error of (a),
representing the output voltage reference,/>
Representing parameters to be set as non-physical constants, and +.>
E R, R is a real number, +.>
Parameters representing constant updates in the system, including known disturbances as well as unknown disturbances, +.>
Representation->
Is a function of the observed value of (a). />
In some embodiments, the gain is adjusted
Is determined by the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing time variable, +_ >
The value of the constant is 0.
In some embodiments, the output voltage
Error of->
Is determined by the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing the output voltage of DAB.
In some embodiments, the super-local model ULM of DAB is determined by the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
represents the output voltage of DAB, < >>
Representation->
Is>
Representing the input of DAB, i.e. shift phase;
representing parameters to be set as non-physical constants, and +.>
E R, R is a real number, +.>
Representing parameters that are continually updated in the system.
In some embodiments, the setting sliding mode observer SMO includes:
setting a sliding mode observer dynamic equation according to the super local model ULM;
setting a sliding mode surface equation according to the error of the sliding mode observer;
and obtaining a sliding mode observer dynamic error equation according to the super local model ULM, the sliding mode observer dynamic equation and the sliding mode surface equation.
In some embodiments, the sliding mode observer dynamic equation is:
wherein, the liquid crystal display device comprises a liquid crystal display device,
represents the output voltage of DAB->
Estimated value of ∈10->
Representing the input of DAB, i.e. shift phase; />
Representing parameters to be set as non-physical constants, and +.>
E R, R is a real number, +.>
State gain representing sliding mode observer SMO, +. >
Representation->
Is a function of the observed value of (a).
In some embodiments, the sliding mode surface equation is:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing a stable equilibrium point>
State trace representing sliding mode observer SMO, +.>
Represents the output voltage of DAB->
Is used for the estimation of the estimated value of (a).
In some embodiments, the obtaining the sliding mode observer dynamic error equation according to the super local model ULM, the sliding mode observer dynamic equation, and the sliding mode surface equation includes:
obtaining an initial sliding mode observer dynamic error equation according to the super local model ULM, the sliding mode observer dynamic equation and the sliding mode surface equation;
and obtaining a final sliding mode observer dynamic error equation according to the initial sliding mode observer dynamic error equation.
In some embodiments, the obtaining an initial sliding mode observer dynamic error equation is:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing the observed value of the sliding surface, +.>
Parameters representing constant updates in the system, +.>
Representing the state trace of the sliding mode observer SMO.
In some embodiments, the final sliding mode observer dynamic error equation is:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing sliding mode observer dynamic error, +.>
Representing the state gain of the sliding mode observer SMO, and +.>
，
Representing the state trace of the sliding mode observer SMO.
In some embodiments, the hyper-local model control model is determined by the following formula:
Wherein, the liquid crystal display device comprises a liquid crystal display device,
representing the input of DAB, < >>
Indicating proportional gain, +.>
Represents the output voltage of DAB->
Error of->
Representing the output voltage reference,/>
Representing parameters to be set as non-physical constants, and +.>
E R, R is a real number, +.>
State trace representing sliding mode observer SMO, +.>
State gain representing sliding mode observer SMO, +.>
Representation->
Is a function of the observed value of (a).
In some embodiments, the parameters that are continually updated in the system include known disturbances as well as unknown disturbances.
In some embodiments, there is also provided a distributed power supply and EV load access microgrid disturbance control device, wherein the device comprises:
a first construction module for constructing a super local model ULM of the dual active full bridge converter DAB;
the first setting module is used for setting the ULM controller based on the super local model ULM;
the second setting module is used for setting a sliding mode observer SMO based on the ULM controller;
the second construction module is used for introducing the sliding mode observer SMO into the construction of the ULM controller to construct a super local model control model so as to control the DAB in the distributed power supply and the electric automobile load to be stably connected in a grid.
In some embodiments, the setting ULM controller includes:
Setting a control law of the ULM controller, wherein the control law is determined by the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing the input of DAB, < >>
Indicating proportional gain, +.>
Represents the output voltage of DAB->
Is used for the error of (a),
representing the output voltage reference,/>
Representing parameters to be set as non-physical constants, and +.>
E R, R is a real number, +.>
Parameters representing constant updates in the system, including known disturbances as well as unknown disturbances, +.>
Representation->
Is a function of the observed value of (a).
In some embodiments, the super-local model ULM of DAB is determined by the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
represents the output voltage of DAB, < >>
Representing the input of DAB, i.e. shift phase; />
Representing parameters to be set as non-physical constants, and +.>
E R, R is a real number, +.>
Parameters representing constant updates in the system, +.>
Representation->
Is a function of the observed value of (a). />
In some embodiments, the setting sliding mode observer SMO includes:
setting a sliding mode observer dynamic equation according to the super local model ULM;
setting a sliding mode surface equation according to the error of the sliding mode observer;
and obtaining a sliding mode observer dynamic error equation according to the super local model ULM, the sliding mode observer dynamic equation and the sliding mode surface equation.
The invention provides a disturbance control method and a disturbance control device for a distributed power supply and EV load access micro-grid, wherein the ULM control strategy is based on SMO, a super-local model of DAB is built by the control strategy based on ULM thought, and a ULM controller is designed; by combining the characteristic of good observation performance of SMO, the unknown item in ULM is estimated by adopting SMO, so that the DC bus voltage can be controlled to have good stability and robustness under large disturbance.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, a brief description will be given below of the drawings required for the embodiments or the prior art descriptions, and it is obvious that the drawings in the following description are some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 shows a flowchart of a distributed power supply and EV load access micro-grid disturbance control method according to an embodiment of the present invention.
Fig. 2 shows a topology diagram of DAB according to an embodiment of the present invention.
Fig. 3 shows an equivalent topology of the topology of DAB in fig. 2.
FIG. 4 shows a control block diagram of a superlocal model control model according to an embodiment of the present invention.
Fig. 5 shows a PI control effect diagram when the output side load increases by 800W under the condition 1 according to the embodiment of the present invention.
FIG. 6 shows a graph of ULM control effect when the output side load increases by 800W under condition 1 according to an embodiment of the present invention.
FIG. 7 shows a bar graph of controller performance under operating condition 1 according to an embodiment of the present invention.
Fig. 8 shows a PI control effect map when the output side load increases by 1000W under the condition 2 according to the embodiment of the present invention.
FIG. 9 shows a ULM control effect graph when the output side load increases by 1000W under condition 2 according to an embodiment of the present invention.
Fig. 10 shows a PI control effect diagram when the output side load is reduced by 800W under the condition 3 according to the embodiment of the present invention.
FIG. 11 shows a ULM control effect graph when the output side load is reduced by 800W under condition 3 according to an embodiment of the present invention.
FIG. 12 shows a bar graph of controller performance under operating condition 3 according to an embodiment of the present invention.
Fig. 13 shows a PI control effect diagram when the output side load is reduced by 1000W under the condition 4 according to the embodiment of the present invention.
FIG. 14 shows a graph of ULM control effect when the output side load is reduced by 1000W under condition 4 according to an embodiment of the present invention.
Fig. 15 shows a PI tracking effect graph when the reference voltage becomes 90V according to an embodiment of the present invention.
Fig. 16 shows a graph of ULM tracking effect when the reference voltage becomes 90V according to an embodiment of the present invention.
Fig. 17 shows a PI tracking effect graph when the reference voltage becomes 85V according to an embodiment of the present invention.
Fig. 18 shows a graph of ULM tracking effect when the reference voltage becomes 85V according to an embodiment of the present invention.
Fig. 19 shows a comparative graph of tracking performance of a controller according to an embodiment of the present invention.
Fig. 20 shows a block diagram of a distributed power supply and EV load access micro-grid disturbance control device according to an embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the novel power system taking new energy power generation as a main body, a large amount of random loads are connected into a micro-grid, and the large disturbance caused by uncertainty of the random loads causes adverse effects on the stability of the direct-current bus voltage. The DC/DC converter is a key device for accessing new energy, an energy storage device, an electric automobile and the like into a micro-grid, and plays an important role in maintaining the stability of the voltage of a direct current bus. The control strategy of the DC/DC converter aiming at large signal disturbance at the present stage depends on an accurate mathematical model, and an actual system with dynamic change is difficult to obtain the accurate model.
Based on the above problems, the invention provides a disturbance control method for accessing a distributed power supply and an EV load into a micro-grid, wherein the distributed power supply comprises a distributed new energy power generation power supply such as wind power generation, photovoltaic power generation and the like, and a EV (Electric Vehicle) load represents an electric automobile load, and the method comprises the following steps:
constructing a super local model ULM of the double active full bridge converter DAB;
setting a ULM controller based on a super local model ULM;
setting a sliding mode observer SMO based on the ULM controller;
and introducing a sliding mode observer SMO to the construction of the ULM controller, and constructing a super local model control model to control DAB to stably grid connection.
The present invention will be described in detail below.
In some embodiments of the invention, the super local model ULM of DAB is as follows:
DAB is used as an interface converter between power equipment such as new energy power generation, an energy storage device, random load and the like and a direct current micro-grid and a direct current bus, and has important significance for maintaining the voltage stability of the direct current bus and the stable operation of the micro-grid. Because of a large number of disturbances such as new energy power supply and random load switching, DAB accurate modeling difficulty is high, and the super local model only needs to measure system input and output, so that the dependence of the model on the structure is reduced, and the control stability of the system can be improved. The invention constructs a super local model of DAB based on DAB topological structure.
In some embodiments of the invention, the DAB topology is as follows:
as shown in fig. 2, the topology structure of DAB is shown, the two ends of the topology structure are dc ports, and the topology structure is composed of two symmetrical H-bridges (all eight switching tubes are fully controllable devices), a high-frequency transformer, an equivalent leakage inductance, an input capacitor and an output capacitor, specifically:
each H bridge comprises two parallel bridge arms, and each bridge arm is also connected with a capacitor in parallel, namely the capacitor connected with the H bridge in parallel on the left side of the graph 2 is the capacitorC i The parallel capacitance of the right H bridge isC o Wherein each bridge arm comprises two switching tubes connected in series, namely the switching tubes of the H bridge at the left side in fig. 2S 1 、S 2 、S 3 and S 4 The right H-bridge comprises a switch tubeS 5 、S 6 、S 7 and S 8 . In fig. 2, each switching tube is antiparallel with a diode.
In addition, in FIG. 2, the midpoint of one of the legs of the left H-bridge is connected to a high frequency transformerTOne end of one side winding of the left H bridge is connected with the midpoint of the other bridge arm of the left H bridge and the high-frequency transformerTThe other end of the winding on one side is connected.
In fig. 2, the midpoint of one of the legs of the right H-bridge is connected to the high-frequency transformerTOne end of the winding on the other side is connected with the midpoint of the other bridge arm of the H bridge on the left side and the high-frequency transformer TThe other end of the winding on the other side is connected.
Wherein in fig. 2, the high frequency transformerTOne end of one side winding of (a) and high frequency transformerTOne end of the winding on the other side is the same name end.
The topology structure has symmetry, and can realize power bidirectional flow. The current flows into the micro-grid from left to right, and specifically, the condition that the current flows into the micro-grid comprises that new energy power generation equipment such as wind power, photovoltaic and the like inputs the current into the micro-grid and the energy storage device inputs the stored electric energy into the micro-grid. When current flows into the micro-grid, taking the DAB topology shown in fig. 2 as an example, the DAB input on the left side of fig. 2 is connected with the direct current output end of the new energy power generation equipment or the direct current output end of the energy storage device, the DAB primary side is used for transmitting electric energy to the DAB secondary side, and the DAB output on the right side of fig. 2 is connected with the direct current input end of the micro-grid.
The equivalent leakage inductance L in fig. 2 shows the leakage inductance generated by the magnetic force lines failing to pass through the secondary coil when the DAB primary coil (the left coil in fig. 2) transmits electric energy to the secondary coil (the right coil in fig. 2), and it is known from the generation reason of the equivalent leakage inductance that the equivalent leakage inductance will appear to the right of DAB when electric energy is transmitted from the DAB right coil to the left coil because DAB is bidirectional. C i 、C o The input and output capacitors are respectively arranged in sequence,Lis equivalent leakage inductance (one end of the equivalent leakage inductance can be regarded as being connected with the midpoint of one of the bridge arms of the left H-bridgeThe other end of the equivalent leakage inductance and the high-frequency transformerTOne end of the one-sided winding is connected),i L for flowing through equivalent leakage inductanceLIs used for the current flow of (a),U L is equivalent to leakage inductanceLThe voltage across the two terminals of the capacitor,U P 、U S the primary voltage and the secondary voltage of the high-frequency transformer are respectively, and the transformation ratio isn:1，U i 、U o Respectively DAB input and output voltages.
And the current flows out of the micro-grid when the current is negative from right to left, and the situation that the current flows out of the micro-grid comprises that the micro-grid supplies power to an energy storage device and an electric automobile load. When current flows out of the micro-grid, taking the DAB topology shown in fig. 2 as an example, the left side of fig. 2 is changed into the DAB output side, and is connected with the direct current input end of the energy storage device or the direct current input end of the electric automobile, the right side of fig. 2 is changed into the DAB input side, the DAB input side is connected with the direct current output end of the micro-grid, and the equivalent leakage inductance L appears in the right coil of the DAB. The input capacitance when current flows into the micro-grid becomes the output capacitance when current flows out of the micro-grid, and the output capacitance when current flows into the micro-grid becomes the input capacitance when current flows out of the micro-grid.
DAB adopts phase shift control, transmission power at present PIs of a size and direction that are all of a phase shiftDDetermining, the expression is:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing a period, +.>
Representing the frequency.
The DAB average equivalent circuit is shown in FIG. 3, in FIG. 3i i (includei i1 、i i2 and i i3 ) Andi o (includei o1 、i o2 and i o3 ) Representing the input side and output side currents, respectively. For nodesNHas the following components
The output side voltage equation is:
in some embodiments of the invention, the super local model of DAB is as follows:
for a nonlinear Single-Input Single-Output (SISO) system, the super local model expression is:
wherein:yis output by the system;uis a system input;Fparameters which are continuously updated in the system, including disturbance parts and uncertain factors;αe R is a parameter to be designed, which is a non-physical constant.
For DAB, the system (DAB system) input is phase shift ratioDOutput is DAB output voltageU o . Based on the super local model of the formula (3), establishing a super local model of DAB, wherein a super local model ULM of DAB is determined by the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representation->
Feedback value (observed value) of +.>
Parameters representing constant updates in the system, including known disturbances as well as unknown disturbances, +.>
Representing the input of DAB, < >>
Representing parameters to be set as non-physical constants, and +. >
E R, R is a real number.
From formula (4), it can be seen that the super local model of DAB is independent of the physical model of DAB, and is controlled by reasonably designing ULM control strategy (law)bParameters and accurately estimate the disturbance thereof
The value can obtain good voltage output characteristics, so that the dependence on an accurate model is reduced, and the method can cope with large signal disturbance caused by new energy access, large-scale random load switching and the like under various conditions.
In some embodiments of the invention, SMO-based ULM control strategies are as follows:
wherein, the setting of ULM controller is as follows:
definition of output voltageU o Wherein the output voltage
Error of->
Is determined by the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
indicating the reference value, i.e. the target value, of the output voltage at which it is desired to stabilize the output voltage, +.>
Represents the output voltage of DAB, < >>
Representing DAB input, i.e. phase shiftingRatio of; />
Representing parameters to be set as non-physical constants, and +.>
∈R，/>
Representing parameters that are continually updated in the system.
Based on the formula of the super local model ULM of formula (4), calculating closed loop according to the PID controller to obtain input
Wherein, the method comprises the steps of, wherein,
is determined by the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
for proportional adjustment of gain (i.e. proportional adjustment coefficient), -for example >
Gain (i.e. integral adjustment coefficient) is adjusted for the integral,>
represents differential adjustment gain (i.e. differential adjustment coefficient),>
and->
0->
To be related to the past and present states only and not to the future state +.>
Representing the output voltage reference,/>
Representing the output voltage +.>
Is a function of the error of (a).
From formulae (4) and (6):
since in practice the number of the devices to be tested is,
、/>
typically designed to be 0, thereby forming an intelligent proportional (iP) controller. Therefore, the formula (7) can be simplified as: />
The solution of the calculated formula (8) is:
wherein: t is t 0 Is the initial time.
From equation (9), the output voltage error
Asymptotically converges to zero, demonstrating that ULM control is asymptotically stable, and furthermore, the term +.>
No longer occurs, simply by solving +>
Can track the output voltage well>
。
According to equation (8), the adjustment gain can be obtained
：
Wherein, the liquid crystal display device comprises a liquid crystal display device,
representing time variable, +_>
The value of the constant is 0.
In summary, it can be seen that the control rule of the final ULM controller can be determined by the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representation->
Is a function of the observed value of (a).
In some embodiments of the invention, the SMO settings are as follows:
unknown items in ULM controller
Is the key to fast elimination of estimation errors, the sliding mode observer SMO has good robustness to uncertain disturbances, so the invention adopts SMO pair +. >
And performing accurate estimation, so as to improve the control performance of the ULM controller.
In the present invention, the sliding mode observer SMO is provided, including:
setting a sliding mode observer dynamic equation according to the super local model ULM;
setting a sliding mode surface equation according to the error of the sliding mode observer;
and obtaining a sliding mode observer dynamic error equation according to the super local model ULM, the sliding mode observer dynamic equation and the sliding mode surface equation.
The setting of the sliding mode observer SMO is described in detail below.
Based on formula (4), setting a sliding mode observer dynamic equation, wherein the sliding mode observer dynamic equation is:
wherein, the liquid crystal display device comprises a liquid crystal display device,
represents the output voltage of DAB->
Estimated value of ∈10->
Representing the state gain of the sliding mode observer SMO,
representation->
Is a function of the observed value of (a).
According to the error of the sliding mode observer, the set sliding mode surface equation is as follows:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing a stable equilibrium point>
Representing the state trace of the sliding mode observer SMO.
In the present invention, the obtaining a sliding-mode observer dynamic error equation according to the super local model ULM, the sliding-mode observer dynamic equation and the sliding-mode surface equation includes:
obtaining an initial sliding mode observer dynamic error equation according to the super local model ULM, the sliding mode observer dynamic equation and the sliding mode surface equation;
And obtaining a final sliding mode observer dynamic error equation according to the initial sliding mode observer dynamic error equation.
Wherein, the steps of the initial observer dynamic error equation obtained by the super local model ULM, the sliding mode observer dynamic equation and the sliding mode surface equation are as follows:
from (4), (12) and (13), the following observer dynamic error equation before transformation is obtained:
based on the formula (14), substituting the sliding mode surface equation into the formula (14), and carrying out a convertible initial sliding mode observer dynamic error equation:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing the observed value of the sliding surface, +.>
Parameters representing constant updates in the system, +.>
Representing the state trace of the sliding mode observer SMO.
After the initial sliding-mode observer dynamic error equation is obtained, in this embodiment, a final sliding-mode observer dynamic error equation is obtained, and the obtaining manner is as follows:
for the initial sliding mode observer dynamic error equation (15),
defined as the stable equilibrium point, select the appropriate +.>
Equation (15) can converge to 0 in a finite time, with the following specific principles:
the following Lyapunov function is selectedV 1 ：
According to Lyapunov stability criteria, it is necessary to ensure
I.e. +.>
Wherein->
>0；
The derivation of formula (16) can be obtained:
wherein, is provided with 
According to formulas (11) and (17), it is possible to obtain:
wherein if and only if
When (I)>
Syndrome of->
And->
Therefore, according to Lyapunov stability principle and the slip form surface meeting the reachable condition, the origin of the equation represented by the formula (15)>
Is stable, state trace->
And->
Convergence to zero in a limited time, +.>
Representation->
Is progressive stable for sliding mode observer SMO,/-for the observations of (a)>
Representation->
And (5) a function after derivation.
According to the slip-form control theory, when the system stably operates on the slip-form surface, the following conditions are satisfied:
thus, the final sliding mode observer dynamic error equation is:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing sliding mode observer dynamic error, +.>
Representing the state gain of the sliding mode observer SMO, and +.>
，
Representing the state trace of the sliding mode observer SMO.
In some embodiments of the invention, SMO-based ULM controllers are as follows:
introducing a sliding mode observer SMO to the construction of the ULM controller, namely substituting the formula (20) into the formula (11), and constructing a super local model control model, wherein an equation corresponding to the finally constructed super local model control model is determined by the following formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing the input of DAB, < >>
Indicating the adjustment of gain->
Represents the output voltage of DAB->
Error of->
Representing the output voltage reference,/ >
Representing parameters to be set as non-physical constants, and +.>
E R, R is a real number, +.>
State trace representing sliding mode observer SMO, +.>
Representing the state gain of the sliding mode observer SMO.
From the above analysis, it can be seen that the design of the control model comprises two major parts of ULM controller and SMO, and according to equations (5) - (11) and equations (20), (21), a control block diagram of SMO-based ULM control system is formed (as shown in fig. 4), wherein in fig. 4,
representing a ride, ->
Representing the summation.
In some embodiments of the invention, the simulation analysis is as follows:
in order to verify the effectiveness of the control strategy provided by the invention, a simulation model shown in fig. 4 is built on a MATLAB/Simulink platform, and the control strategy of the invention is simulated and compared with the traditional PI control. The simulation parameters are shown in table 1 (DAB parameter table corresponding to superlocal model ULM).
TABLE 1
In some embodiments of the invention, simulation results at different load disturbances are analyzed as follows:
in order to verify the effectiveness of the control strategy, the load is changed to serve as system disturbance, and four typical working conditions are set for simulation test. In the results of the simulation, the simulation results,U i 、U o respectively input and output voltages are respectively used for the control circuit,I i 、I o respectively input and output currents.
Working condition 1: at 0.005s, the output side load increases from 200W to 1000W, and simulation results of the conventional PI control and ULM control strategies are shown in fig. 5 (PI control effect graph when the output side load increases by 800W under the condition 1) and fig. 6 (ULM control effect graph when the output side load increases by 800W under the condition 1), respectively;
Wherein in FIG. 5, the steps are sequentially from top to bottomI i 、I o and U o Wherein:
for the followingI i The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/a), and is divided in units of difference 5 (exemplary, 0, 5, 10).
For the followingI o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/a), and is divided in units of difference 5 (exemplary, 0, 5, 10).
For the followingU o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the voltage magnitude (U/V), and is divided in units of difference 0.5 (exemplary, 98.5, 99.0, 99.5, 100.0, 100.5),U o within 0.657ms, from 100.0V to a minimum value (the minimum value is less than 98.5V), and then from the minimum value, up to a final value by 0.664V, which is different from 100.0V by 0.965V;
wherein in FIG. 6, the steps are sequentially from top to bottomI i 、I o and U o Wherein:
for the followingI i The description of the horizontal and vertical axes is as follows:
the abscissa is time t(0.005 s/cell); the ordinate indicates the current magnitude (I/a), and is divided in units of difference 5 (exemplary, 0, 5, 10).
For the followingI o Waveform diagram of (1)The description of the abscissa is:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/a), and is divided in units of difference 5 (exemplary, 0, 5, 10).
For the followingU o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the voltage magnitude (U/V), and is divided in units of difference 0.5 (exemplary, 98.5, 99.0, 99.5, 100.0, 100.5),U o within 0.352ms, from 100.0V to a minimum value (the minimum value is between 99.5-100.0V), then from the minimum value again, up to 0.147V to the final value, and the final value has an error of 0.183 from the actual value.
According to the simulation results shown in fig. 5 and 6, the proposed control strategy is quantitatively analyzed by adopting performance indexes of overshoot, adjustment time and steady-state error, and the analysis result is shown in fig. 7 (a histogram of the performance of the controller under the working condition 1).
The coordinates in fig. 7 are divided into X and Y axes, wherein the X axis represents steady-state error (V), adjustment time (ms), and overshoot (V) of the corresponding control, each of which has two control states of PI control and UML control, and the Y axis shows the value of the corresponding performance index under the corresponding control, which is divided in units of 0.20 (exemplary, 0, 0.20, 0.40, 0.60, 0.80, 1).
As can be seen from fig. 7, compared with PI control, the control strategy provided by the present invention has the advantages of faster adjustment speed, shorter adjustment time, lower overshoot, and reduced steady-state error after the output voltage is stabilized. Therefore, the control strategy provided by the invention has better dynamic performance and better rapidity and stability.
Working condition 2: at 0.005s, the output side load increases from 200W to 1200W, and simulation results of the conventional PI control and ULM control strategies are shown in fig. 8 (PI control effect graph when the output side load increases by 1000W under the condition 2) and fig. 9 (ULM control effect when the output side load increases by 1000W under the condition 2), respectively.
Wherein in FIG. 8, the steps are sequentially from top to bottomI i 、I o and U o Wherein:
for the followingI i The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/a), and is divided in units of difference 5 (exemplary, 0, 5, 10, 15, 20).
For the followingI o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/a), and is divided in units of difference 5 (exemplary, 0, 5, 10).
For the followingU o The description of the horizontal and vertical axes is as follows:
The abscissa is timet(0.005 s/cell); the ordinate indicates the voltage magnitude (U/V) and is divided in units of difference 1 (exemplary, 97, 98, 99, 100);
wherein in FIG. 9, the steps are sequentially from top to bottomI i 、I o and U o Wherein:
for the followingI i The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/a), and is divided in units of difference 5 (exemplary, 0, 5, 10).
For the followingI o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/a), and is divided in units of difference 5 (exemplary, 0, 5, 10).
For the followingU o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the voltage magnitude (U/V) and the difference value0.5 (exemplary, 99.5, 100.0, 100.5),U o within 0.436ms, from 100.0V to a minimum value (the minimum value is between 99.5-100.0V), and then from the minimum value, up to a final value by 0.191V, with an error of 0.245 from the actual value.
In the working condition 2, when the traditional PI control is adopted, the fluctuation of the output voltage is large, and the stable operation of the system cannot be maintained. The control strategy provided by the invention can still maintain the stability of the DC bus voltage under large disturbance, so as to maintain the stable operation of the micro-grid, and the strategy provided by the invention is verified to have good immunity and robustness.
Working condition 3: at 0.005s, the output side load is reduced from 1000W to 200W, and as shown in fig. 10 (PI control effect graph when the output side load is reduced by 800W under the condition 3) and fig. 11 (ULM control effect graph when the output side load is reduced by 800W under the condition 3), the simulation results of the conventional PI control and ULM control strategies are respectively shown.
Wherein in FIG. 10, the steps are sequentially from top to bottomI i 、I o and U o Wherein:
for the followingI i The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/a) and is divided in units of difference 5 (exemplary, -5, 0, 5, 10).
For the followingI o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 2 (exemplary, -8, -6, -4, -2, 0).
For the followingU o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the voltage magnitude (U/V), and divided in units of difference 0.5 (exemplary, 100.0, 100.5, 101.0, 101.5),U o within 1.625ms from100.0V rises to a maximum value (the maximum value is greater than 101.5V);
wherein in FIG. 11, the steps are sequentially from top to bottomI i 、I o and U o Wherein:
for the followingI i The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 5 (exemplary, -10, -5, 0, 5).
For the followingI o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 2 (exemplary, -8, -6, -4, -2, 0).
For the followingU o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the voltage magnitude (U/V), and divided in units of difference 0.5 (exemplary, 100.0, 100.5, 101.0, 101.5), U o The waveform of (a) rises from 100.0V to a maximum value (the maximum value is between 101.0-101.5V) and then falls from the maximum value to a final value within 0.544ms, and the difference between the final value and 100.0V is 1.371V.
Based on the simulation results shown in fig. 10 and 11, the same method was used to conduct comparative analysis on the controller, as shown in fig. 12 (histogram of the controller performance under the condition 3). Compared with PI control, the control strategy provided by the invention has the advantages of high adjustment speed, reduced steady-state error and better adjustment performance and steady-state performance.
The coordinates in fig. 12 are divided into X and Y axes, wherein the X axis represents steady-state error (V), adjustment time (ms), and overshoot (V) of the corresponding control, each of which has two control states of PI control and UML control, and the Y axis shows a value of the corresponding performance index in units of 0.20 (exemplary, 0, 0.20, 0.40, 0.60, 0.80, 1, 1.20, 1.40, 1.60, etc.).
Working condition 4: at 0.005s, the output side load was reduced from 1200W to 200W. Fig. 13 (PI control effect graph when the output side load is reduced by 1000W under the condition 4) and fig. 14 (ULM control effect graph when the output side load is reduced by 1000W under the condition 4) are simulation results of the conventional PI control and ULM control strategies, respectively.
Wherein in FIG. 13, the steps are sequentially from top to bottomI i 、I o and U o Wherein:
for the followingI i The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 10 (exemplary, -20, -10, 0, 10, 20).
For the followingI o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 5 (exemplary, -10, -5, 0).
For the followingU o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the voltage magnitude (U/V) and is divided in units of difference 2 (exemplary, 96, 98, 100, 102).
Wherein in FIG. 14, the steps are sequentially from top to bottomI i 、I o and U o Wherein:
for the followingI i The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 5 (exemplary, -10, -5, 1).
For the followingI o Is described as the horizontal and vertical coordinates ：
The abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 5 (exemplary, -10, -5, 0).
For the followingU o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the voltage magnitude (U/V), and is divided in units of difference 2 (exemplary, 100.0, 100.5, 101.0, 101.5),U o the waveform of (a) rises from 100.0V to a maximum value (which is greater than 101.5V) and then drops from the maximum value by 0.158 to a final value within 0.598ms, with a 1.399V difference between the final value and 100.0.
According to the simulation results shown in fig. 13 and 14, in the working condition 4, when the conventional PI control is adopted, the anti-interference capability is poor, the output voltage fluctuation is large, and the system fails to stably operate. The control strategy provided by the invention has good robustness, can still keep the stability of the voltage of the direct current bus under large disturbance, and has good steady state and dynamic performance.
The comparative analysis results of the control performances of the PI and ULM control methods under the above 4 conditions are shown in table 2 (ULM and PI control performance comparison chart).
TABLE 2
Table 2 shows that ULM control is significantly better than PI control when the load is increased by 800W, wherein steady state error is reduced by 81.04%, settling time is reduced by 46.42%, overshoot is reduced by 77.86%; when the load is reduced by 800W, ULM is reduced by 24.67% compared with PI control regulation time, steady state error is reduced by 66.52%, ULM strategy is better in rapidity and stability, and control performance is effectively improved. When the load is increased or reduced by 1000W, PI control is unstable, ULM control has better anti-interference performance, can still keep the stability of the voltage of the direct current bus, and has good steady state and dynamic performance.
In some embodiments of the invention, the tracking performance simulation results are analyzed as follows:
in order to verify the tracking performance of the control strategy provided by the invention on the output voltage, the self-adaptive capacity of the ULM controller on the change of the reference voltage is tested, and the simulation test is carried out on two working conditions, and the results are shown in figure 15 (PI tracking effect graph when the reference voltage is changed to 90V), figure 16 (ULM tracking effect graph when the reference voltage is changed to 90V), figure 17 (PI tracking effect graph when the reference voltage is changed to 85V) and figure 18 (ULM tracking effect graph when the reference voltage is changed to 85V).
Wherein in FIG. 15, the steps are sequentially from top to bottomI i 、I o and U o Wherein:
for the followingI i The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 5 (exemplary, -10, -5, 0).
For the followingI o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 2 (exemplary, -4, -2, 0, 2).
For the followingU o The description of the horizontal and vertical axes is as follows:
The abscissa is timet(0.005 s/cell); the ordinate indicates the voltage magnitude (U/V), and is divided in units of difference 5 (exemplary, 90, 95, 100),U o the waveform of (2) falls to a minimum value within 1.821ms, the minimum value is greater than 90V, and the tracking error of the minimum value is 1.96V.
Wherein in FIG. 16, the steps are sequentially from top to bottomI i 、I o and U o Wherein:
for the followingI i The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitudeSmall (I/a), and divided in units of difference 5 (exemplary, -10, -5, 0).
For the followingI o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 2 (exemplary, -4, -2, 0, 2).
For the followingU o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the voltage magnitude (U/V), and is divided in units of difference 5 (exemplary, 90, 95, 100),U o within 1.049ms from 100.0V to a minimum value (the minimum value is between 90-95V) with a minimum tracking error of 1.06V.
Wherein in FIG. 17, the steps are sequentially from top to bottomI i 、I o and U o Wherein:
for the followingI i The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 5 (exemplary, -10, -5, 0, 5).
For the followingI o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 5 (exemplary, -10, -5, 0).
For the followingU o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the voltage magnitude (U/V), and is divided in units of difference 5 (exemplary, 85, 90, 95, 100),U o within 1.939ms from 100.0V to a minimum value (the minimum value is between 85-90V) with a minimum tracking error of 1.99V.
Wherein in FIG. 18, the steps are sequentially from top to bottomI i 、I o and U o Wherein:
for the followingI i The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 5 (exemplary, -10, -5, 0, 5).
For the followingI o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the current magnitude (I/A) and is divided in units of difference 5 (exemplary, -10, -5, 0).
For the followingU o The description of the horizontal and vertical axes is as follows:
the abscissa is timet(0.005 s/cell); the ordinate indicates the voltage magnitude (U/V) and is divided in units of difference 5 (exemplary, 85, 90, 95, 100,U o within 1.702ms from 100.0V to a minimum value (the minimum value is between 85-90V) with a minimum tracking error of 1.17V.
Working condition 1: the reference voltage is started to be 100V, and at 0.005s, the reference voltage becomes 90V, as shown in fig. 14 and 15, which are tracking effects of conventional PI and ULM control, respectively.
As shown in fig. 15 and 16, when the reference voltage is changed from 100V to 90V, the ULM control reduces the adjustment time from 2.178% to 1.178% compared with the PI control, and has a better tracking effect and a better adaptive capacity to the reference voltage change.
Working condition 2: the reference voltage was started at 100V and at 0.005s the reference voltage became 85V, as shown in fig. 17 and 18 for the tracking effect of PI and ULM control, respectively.
As shown in fig. 17 and 18, when the reference voltage is changed from 100V to 85V, compared with PI control, the control strategy provided by the invention has the advantages of fast tracking speed, reduced adjustment time and reduced tracking error from 2.341% to 1.376%. Therefore, the ULM control strategy provided by the invention has the advantages of faster response speed along with the change of the reference voltage and better tracking performance.
The comparative analysis of the tracking performance of the PI and ULM control methods under the above-mentioned conditions is shown in fig. 19 (a comparative graph of the tracking performance of the controller), in which in fig. 19, the diagonally striped filled columns correspond to the adjustment time, and the diagonally striped filled columns correspond to the tracking error.
FIG. 19 shows that ULM control tracking effect is better than PI control when the reference voltage becomes 90V, with 42.39% decrease in settling time and 45.91% decrease in tracking error; when the reference voltage becomes 85V, the ULM is reduced by 12.22% compared to the PI control adjustment time, and the tracking error is reduced by 41.22%. Therefore, the response speed of the ULM controller following the reference voltage change is faster, the tracking error is smaller, and the tracking performance is better.
The coordinates in fig. 19 are divided into X and Y axes, wherein the X axis represents the control condition 1 PI control, the control condition 1 UML control, the control condition 2 PI control, the control condition 2 UML control, the control condition 1 PI control, the control condition 1 UML control, the control condition 2 PI control, and the control condition 2 UML are each provided with the adjustment time ms and the tracking error% correspondingly, and the Y axis shows the value of the corresponding performance index under the corresponding control, which is divided in units of 0.5 (exemplary, 0, 0.5, 1, 1.5, 2, 2.5).
Aiming at the problems of intermittent disturbance of new energy, undetectable disturbance of random load, complex system modeling and the like, the invention provides a ULM control strategy based on SMO. By simulation and experimental comparative analysis with the traditional PI control, the following conclusion is obtained:
1) The proposed ULM control strategy avoids the dependence of the model on the system structure, and has good control performance by combining with an SMO observer;
2) Under different load disturbance, DAB is compared and tested by using the traditional PI control and ULM control respectively, and under the same working condition, the strategy provided by the invention is obviously superior to the traditional PI control, the PI control cannot solve the large disturbance, and the ULM can still maintain the stability of the DC bus voltage and has good dynamic performance.
3) The reference voltage variation test result shows that the ULM has faster response speed and better tracking effect than PI control.
In summary, compared with PI control, the control strategy provided by the present invention can maintain the dc bus voltage stable in the presence of large disturbance, thereby maintaining the stable operation of the dc micro-grid.
On the other hand, as shown in fig. 20, the present invention further provides a distributed power supply and EV load access micro-grid disturbance control device, where the device includes:
A first construction module for constructing a super local model ULM of the dual active full bridge converter DAB;
the first setting module is used for setting the ULM controller based on the super local model ULM;
the second setting module is used for setting a sliding mode observer SMO based on the ULM controller;
the second construction module is used for introducing the sliding mode observer SMO into the construction of the ULM controller to construct a super local model control model so as to control the DAB in the distributed power supply and the electric automobile load to be stably connected in a grid.
The invention provides a SMO-based ULM control strategy, which builds a super-local model of DAB based on the ULM idea and designs a ULM controller; by combining the characteristic of good observation performance of SMO, the unknown item in ULM is estimated by adopting SMO, and the stability of the SMO is demonstrated by Lyapunov stability theory. And finally, constructing a MATLAB/Simulink simulation model, and verifying that the direct-current bus voltage has good stability and robustness under large disturbance, thereby verifying the effectiveness and the immunity of the control strategy provided by the invention.
The present invention is not limited to the above-mentioned embodiments, but is not limited to the above-mentioned embodiments, and any simple modification, equivalent changes and modification made to the above-mentioned embodiments according to the technical matters of the present invention can be made by those skilled in the art without departing from the scope of the present invention.
Claims (17)
1. The disturbance control method for the distributed power supply and EV load access micro-grid is characterized by comprising the following steps:
constructing a super local model ULM of the double active full bridge converter DAB;
setting a ULM controller based on a super local model ULM;
setting a sliding mode observer SMO based on the ULM controller;
and introducing a sliding mode observer SMO to the construction of the ULM controller, and constructing a super local model control model to control DAB in the distributed power supply and the electric automobile load to be stably connected in a grid.
2. The distributed power supply and EV load access micro-grid perturbation control method according to claim 1, characterized in that the setting up ULM controller comprises:
setting a control law of the ULM controller, wherein the control law is determined by the following formula:
3. The distributed power supply and EV load access micro-grid perturbation control method according to claim 2, characterized in that the gain is adjusted proportionally 
Is determined by the following formula:
4. A distributed power supply and EV load access micro-grid disturbance control method according to claim 2 or 3, characterized in that the output voltage
Error of->
Is determined by the following formula:
5. The distributed power supply and EV load access micro-grid perturbation control method according to claim 1, characterized in that the ultra-local model ULM of DAB is determined by the following formula:
6. The distributed power supply and EV load access micro-grid perturbation control method according to claim 1, characterized in that the setting sliding mode observer SMO comprises:
setting a sliding mode observer dynamic equation according to the super local model ULM;
setting a sliding mode surface equation according to the error of the sliding mode observer;
and obtaining a sliding mode observer dynamic error equation according to the super local model ULM, the sliding mode observer dynamic equation and the sliding mode surface equation.
7. The distributed power supply and EV load access micro-grid perturbation control method of claim 6, wherein the sliding mode observer dynamic equation is:
8. The distributed power supply and EV load access micro-grid perturbation control method of claim 6, wherein the slip-form surface equation is:
9. The method for controlling disturbance of a distributed power supply and EV load access micro-grid according to claim 6, wherein obtaining a sliding-mode observer dynamic error equation according to a super-local model ULM, a sliding-mode observer dynamic equation, and a sliding-mode surface equation comprises:
obtaining an initial sliding mode observer dynamic error equation according to the super local model ULM, the sliding mode observer dynamic equation and the sliding mode surface equation;
And obtaining a final sliding mode observer dynamic error equation according to the initial sliding mode observer dynamic error equation.
10. The method for controlling disturbance of a distributed power supply and EV load access micro-grid according to claim 9, wherein the obtaining an initial sliding-mode observer dynamic error equation is:
11. The distributed power supply and EV load access micro-grid perturbation control method of claim 10, characterized in that the final sliding-mode observer dynamic error equation is:
12. The distributed power supply and EV load access micro-grid perturbation control method of claim 10, wherein the super-local model control model is determined by the following formula:
13. The method for controlling disturbance of a distributed power supply and EV load access micro-grid according to claim 5 or 10, characterized in that the parameters updated continuously in the system include known disturbances and unknown disturbances.
14. The utility model provides a distributed power source and EV load access micro grid disturbance controlling means which characterized in that, the device includes:
a first construction module for constructing a super local model ULM of the dual active full bridge converter DAB;
the first setting module is used for setting the ULM controller based on the super local model ULM;
the second setting module is used for setting a sliding mode observer SMO based on the ULM controller;
the second construction module is used for introducing the sliding mode observer SMO into the construction of the ULM controller to construct a super local model control model so as to control the DAB in the distributed power supply and the electric automobile load to be stably connected in a grid.
15. The distributed power and EV load access microgrid disturbance control device according to claim 14, characterized in that said setting up a ULM controller comprises:
Setting a control law of the ULM controller, wherein the control law is determined by the following formula:
16. The distributed power supply and EV load access micro-grid perturbation control device according to claim 14, characterized in that the ultra-local model ULM of DAB is determined by the following formula:
17. The distributed power supply and EV load access microgrid disturbance control device according to any one of claims 14 to 16, characterized in that the set sliding mode observer SMO comprises:
setting a sliding mode observer dynamic equation according to the super local model ULM;
Setting a sliding mode surface equation according to the error of the sliding mode observer;
and obtaining a sliding mode observer dynamic error equation according to the super local model ULM, the sliding mode observer dynamic equation and the sliding mode surface equation.
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