Microgrid voltage control method based on t-s fuzzy adaptive sliding mode observer

Abstract

The application discloses a micro-grid voltage control method based on a T-S fuzzy adaptive sliding mode observer, and comprises the following steps: an islanded AC / DC hybrid micro-grid operation model is established through a differential equation; an islanded AC / DC hybrid micro-grid state space form is constructed through a state space method; fuzzy rules and membership functions are designed, and an islanded AC / DC hybrid micro-grid T-S fuzzy model is established; a state observer is established to estimate complete state information in real time and offset external disturbances; two sliding mode functions are constructed through estimation errors and tracking errors, so that system output states track reference model output states; according to the islanded AC / DC hybrid micro-grid T-S fuzzy model, a T-S fuzzy adaptive sliding mode controller is established based on the state observer and the two sliding mode functions, and voltage tracking control is realized by output feedback. Through the observer and the sliding mode control, the application realizes voltage control of the islanded AC / DC hybrid micro-grid T-S fuzzy model, and guarantees the stability of a closed-loop system.

Description

Technical Field

[0001] This invention belongs to the field of power grids and relates to AC / DC hybrid microgrid voltage control technology, specifically to a voltage control method for islanded AC / DC hybrid microgrids based on a TS fuzzy adaptive sliding mode observer. Background Technology

[0002] The widespread application of new energy resources has driven the development of power system structures and operating modes. Microgrids, as a flexible, reliable, and efficient power supply mode, have emerged, allowing distributed renewable energy generation to be utilized by local loads. Based on power source type, microgrids can be divided into AC microgrids and DC microgrids, both of which can operate in off-grid or grid-connected modes. In off-grid mode, power quality may be affected if the main grid supply is interrupted.

[0003] Distributed generation in microgrids mainly consists of renewable energy generation units such as wind turbines and photovoltaic systems. Their output power is affected by factors such as weather conditions, equipment lifespan, and natural disasters. Furthermore, the uncertainty of local loads leads to uneven power distribution within the microgrid, causing fluctuations in voltage, current, and frequency. Hybrid AC / DC microgrids are more complex than independent DC or AC microgrids. The core challenge lies in voltage control, specifically the design challenges of AC / DC coupling, nonlinear dynamics, and multi-source interference.

[0004] Furthermore, in islanded operation mode, state information is collected through sensors. In reality, some system state variables cannot be directly measured in actual systems. Summary of the Invention

[0005] Purpose of the invention: To address the voltage control issues arising from the inability to directly measure some system state information, external disturbances, and the coupling relationship between AC and DC components, this invention provides a microgrid voltage control method based on a TS fuzzy adaptive sliding mode observer. Through the observer and sliding mode control, voltage control of the TS fuzzy model of an islanded AC / DC hybrid microgrid is achieved, ensuring the stability of the closed-loop system.

[0006] Technical Solution: To achieve the above objectives, this invention provides a microgrid voltage control method based on a TS fuzzy adaptive sliding mode observer, comprising the following steps:

[0007] S1: Based on the microgrid framework and energy conversion relationship, an islanded AC / DC hybrid microgrid operation model is established through differential equations;

[0008] S2: Establish an islanded AC / DC hybrid microgrid operation model for the differential equations, and construct the state-space form of the islanded AC / DC hybrid microgrid using the state-space method;

[0009] S3: Based on the state-space form of the islanded AC / DC hybrid microgrid, fuzzy rules and membership functions are designed according to the coupling relationship between the AC and DC parts to establish the TS fuzzy model of the islanded AC / DC hybrid microgrid;

[0010] S4: Considering external disturbances and combining the fact that the system state cannot be directly measured, establish a state observer to estimate the complete state information in real time and counteract external disturbances;

[0011] S5: By estimating the error and tracking the error, two sliding mode functions are constructed so that the system output state tracks the reference model output state, thereby making the tracking error approach zero;

[0012] S6: Based on the TS fuzzy model of the islanded AC / DC hybrid microgrid, a TS fuzzy adaptive sliding mode controller is established based on the state observer and two sliding mode functions, and voltage tracking control is achieved by using output feedback.

[0013] Furthermore, the islanded AC / DC hybrid microgrid operation model in step S1 is expressed as follows:

[0014]

[0015] in, and These represent the input and output voltages of the DC / DC Boost converter, respectively. This is the input current of the DC / DC Boost converter; and These represent the equivalent inductance and capacitance of the DC / DC Boost converter, respectively. and These represent the direct component and quadrature component of the input voltage of the LC filter, respectively. , and These are the first control signal, the second control signal, and the third control signal of the microgrid system, respectively. and express , and The conversion relationship between them; and These represent the inductance and resistance of the LC filter, respectively. This indicates the capacitance value of the LC filter. It is the corrected angular velocity for the microgrid frequency; and These represent the direct component and quadrature component of the output current of the LC filter, respectively. and These represent the direct component and quadrature component of the LC filter output voltage, respectively. and These represent the direct and quadrature components of the supply current in an islanded microgrid, respectively. The derivative of the direct component of the output voltage of the LC filter. The derivative of the orthogonal component of the output voltage of the LC filter. This represents the derivative of the direct component of the output current of the LC filter. This represents the derivative of the quadrature component of the output current of the LC filter. This represents the derivative of the output voltage of the DC / DC Boost converter. This represents the derivative of the input current of the DC / DC Boost converter.

[0016] Furthermore, the state-space form of the islanded AC / DC hybrid microgrid in step S2 is expressed as follows:

[0017] definition It is a vector of state variables. It is a vector for controlling input. It is the vector of the disturbance;

[0018] The system is redescribed as follows:

[0019]

[0020] Among them, the constants are composed of and These represent the parameter matrix and disturbance matrix of the control system, respectively. It is the input matrix of the control system.

[0021] Furthermore, the establishment of the fuzzy model of the islanded AC / DC hybrid microgrid TS in step S3 includes:

[0022] Assumption , , and The TS fuzzy model is described by the IF-THEN rule;

[0023] Rule :IF yes , yes , yes and yes THEN:

[0024]

[0025] in, Indicates the number of fuzzy rules; , , and It is the first A fuzzy set of fuzzy rules; premise variables It is considered bounded, with its upper and lower bounds being respectively... and C represents the output matrix;

[0026] Through membership function Constructing a TS fuzzy model:

[0027]

[0028] in, Indicates the corresponding to the first The membership function of a linear subsystem is expressed as follows:

[0029]

[0030] in, Indicates the first The weight of each rule; Indicates the first Membership functions between the premise variables and the fuzzy set.

[0031] Furthermore, the establishment of the state observer in step S4 includes:

[0032]

[0033] in, To estimate the state, and Same dimensions; The observer gain matrix is... For the defined discontinuous vector; This is the derivative of the state observer.

[0034] Furthermore, in step S5, the two sliding mode functions are respectively related to the estimation error. sliding mode function and about tracking error sliding mode function .

[0035] Furthermore, in step S5, regarding the estimation error... sliding mode function The construction methods include:

[0036] The state estimation error is defined as:

[0037]

[0038] Regarding estimation error The sliding mode function is defined as follows:

[0039]

[0040] in, It is a constant full-rank matrix and , making It is a non-singular matrix, while the observer gain matrix is... ;

[0041] The sliding mode function is redefined as follows:

[0042]

[0043] Where N is the sliding surface construction coefficient matrix; This is the output estimation error.

[0044] Furthermore, regarding the tracking error in step S5... sliding mode function The construction methods include:

[0045] State tracking error is defined as:

[0046]

[0047] in, As a reference model state, output tracking error The definition of is:

[0048]

[0049] in, To output a reference model;

[0050] Regarding tracking error The sliding mode function is defined as follows:

[0051]

[0052] in, It is a full-rank matrix, such that It is a non-singular matrix; It is a constant matrix, such that It becomes a Hurwitz matrix.

[0053] Furthermore, the expression of the TS fuzzy adaptive sliding mode controller in step S6 includes:

[0054]

[0055] in, It is an auxiliary control function, and its specific design is as follows:

[0056] in, , For adaptive compensation terms, To control the sliding mode gain of the control layer, This is an adaptive law.

[0057] Beneficial effects: Compared with the prior art, this invention constructs a TS fuzzy operation model of an islanded AC / DC hybrid microgrid to simulate the system under external disturbances and when some states cannot be directly measured. It also constructs a voltage control scheme for the islanded AC / DC hybrid microgrid based on a TS fuzzy adaptive sliding mode observer. This control strategy successfully solves the core problems of nonlinearity, strong coupling, and disturbance sensitivity of islanded AC / DC microgrids, and achieves the comprehensive goals of high-precision state observation, chatter-free sliding mode control, and high-quality power output, thus ensuring the stable operation of the islanded AC / DC hybrid microgrid. Attached Figure Description

[0058] Figure 1 This is a flowchart of the method of the present invention;

[0059] Figure 2 Diagram of an isolated AC / DC hybrid microgrid power system;

[0060] Figure 3 for Comparison diagram of output system status and output reference model;

[0061] Figure 4 for Comparison diagram of output system status and output reference model;

[0062] Figure 5 for Comparison diagram of output system status and output reference model;

[0063] Figure 6 This is a graph of the adaptive law. Detailed Implementation

[0064] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0065] Example 1:

[0066] like Figure 1As shown, this embodiment provides a voltage control method for islanded AC / DC hybrid microgrids based on a TS fuzzy adaptive sliding mode observer, including the following steps:

[0067] S1: Based on the microgrid framework and energy conversion relationship, an islanded AC / DC hybrid microgrid operation model is established through differential equations;

[0068] The operation model of an isolated AC / DC hybrid microgrid is expressed as follows:

[0069]

[0070] in, and These represent the input and output voltages of the DC / DC Boost converter, respectively. This is the input current of the DC / DC Boost converter; and These represent the equivalent inductance and capacitance of the DC / DC Boost converter, respectively. and These represent the direct component and quadrature component of the input voltage of the LC filter, respectively. , and These are the first control signal, the second control signal, and the third control signal of the microgrid system, respectively. and express , and The conversion relationship between them; and These represent the inductance and resistance of the LC filter, respectively. This indicates the capacitance value of the LC filter. It is the corrected angular velocity for the microgrid frequency; and These represent the direct component and quadrature component of the output current of the LC filter, respectively. and These represent the direct component and quadrature component of the LC filter output voltage, respectively. and These represent the direct and quadrature components of the supply current in an islanded microgrid, respectively. The derivative of the direct component of the output voltage of the LC filter. The derivative of the orthogonal component of the output voltage of the LC filter. This represents the derivative of the direct component of the output current of the LC filter. This represents the derivative of the quadrature component of the output current of the LC filter. This represents the derivative of the output voltage of the DC / DC Boost converter. This represents the derivative of the input current of the DC / DC Boost converter.

[0071] S2: Establish an islanded AC / DC hybrid microgrid operation model for the differential equations, and construct the state-space form of the islanded AC / DC hybrid microgrid using the state-space method;

[0072] The state-space representation of an islanded AC / DC hybrid microgrid is as follows:

[0073] definition It is a vector of state variables. It is a vector for controlling input. It is the vector of the disturbance;

[0074] The system is redescribed as follows:

[0075]

[0076] Among them, the constants are composed of and These represent the parameter matrix and disturbance matrix of the control system, respectively. It is the input matrix of the control system;

[0077] In this embodiment , and It is expressed by the following formula:

[0078]

[0079] S3: Based on the state-space form of the islanded AC / DC hybrid microgrid, fuzzy rules and membership functions are designed according to the coupling relationship between the AC and DC parts to establish the TS fuzzy model of the islanded AC / DC hybrid microgrid;

[0080] To facilitate the design process of sliding mode control strategies, a TS fuzzy model is used to linearize the dynamic model of the islanded microgrid. Assuming... , , and The TS fuzzy model is described by the IF-THEN rule;

[0081] Rule :IF yes , yes , yes and yes THEN:

[0082]

[0083] in, Indicates the number of fuzzy rules; , , and It is the first A fuzzy set of fuzzy rules; premise variables It is considered bounded, with its upper and lower bounds being respectively... and C represents the output matrix;

[0084] In this embodiment The specific expression is as follows:

[0085]

[0086]

[0087]

[0088]

[0089] Through membership function Constructing a TS fuzzy model:

[0090]

[0091] in, Indicates the corresponding to the first The membership function of a linear subsystem is expressed as follows:

[0092]

[0093] in, Indicates the first The weight of each rule; Indicates the first Membership functions between the premise variables and the fuzzy set; in this embodiment This can be summarized as follows:

[0094]

[0095]

[0096]

[0097]

[0098] S4: Considering external disturbances and combining the fact that the system state cannot be directly measured, establish a state observer to estimate the complete state information in real time and counteract external disturbances;

[0099] The establishment of the state observer includes:

[0100]

[0101] in, To estimate the state, and Same dimensions; The observer gain matrix is... For the defined discontinuous vector; This is the derivative of the state observer.

[0102] S5: By estimating the error and tracking the error, two sliding mode functions are constructed so that the system output state tracks the reference model output state, thereby making the tracking error approach zero;

[0103] The two sliding mode functions are respectively related to the estimation error. sliding mode function and about tracking error sliding mode function ;

[0104] Regarding estimation error sliding mode function The construction methods include:

[0105] The state estimation error is defined as:

[0106]

[0107] Regarding estimation error The sliding mode function is defined as follows:

[0108]

[0109] in, It is a constant full-rank matrix and , making It is a non-singular matrix, while the observer gain matrix is... ;

[0110] The sliding mode function is redefined as follows:

[0111]

[0112] Where N is the sliding surface construction coefficient matrix; This is the output estimation error.

[0113] Regarding tracking error sliding mode function The construction methods include:

[0114] State tracking error is defined as:

[0115]

[0116] in, As a reference model state, output tracking error The definition of is:

[0117]

[0118] in, To output a reference model;

[0119] Regarding tracking error The sliding mode function is defined as follows:

[0120]

[0121] in, It is a full-rank matrix, such that It is a non-singular matrix; It is a constant matrix, such that It becomes a Hurwitz matrix.

[0122] S6: Based on the TS fuzzy model of the islanded AC / DC hybrid microgrid, a TS fuzzy adaptive sliding mode controller is established based on the state observer and two sliding mode functions, and voltage tracking control is achieved by using output feedback;

[0123] The expressions for the TS fuzzy adaptive sliding mode controller include:

[0124]

[0125] in, It is an auxiliary control function, and its specific design is as follows:

[0126] in, , For adaptive compensation terms, To control the sliding mode gain of the control layer, This is an adaptive law.

[0127] This embodiment constructs a TS fuzzy operation model of an islanded AC / DC hybrid microgrid to simulate the system under external disturbances and when some states cannot be directly measured. It also constructs a voltage control scheme for the islanded AC / DC hybrid microgrid based on a TS fuzzy adaptive sliding mode observer. This control strategy successfully solves the core problems of nonlinearity, strong coupling, and disturbance sensitivity of the islanded AC / DC microgrid, and achieves the comprehensive goals of high-precision state observation, chatter-free sliding mode control, and high-quality power output, thus ensuring the stable operation of the islanded AC / DC hybrid microgrid.

[0128] Example 2:

[0129] To verify the effectiveness and effect of the method of the present invention, this embodiment uses... Figure 2 The power system model based on an islanded AC / DC hybrid microgrid shown was used as the simulation research object, and the following experiments and data analyses were conducted:

[0130] like Figure 2 As shown in Table 1, the specific parameter values ​​of the system are as follows:

[0131] Table 1 System Parameters

[0132]

[0133] Setting the initial state of the microgrid system Estimate the state and reference model And set the parameters as follows: , , , , , , , , , , , , .

[0134] Matrix in sliding mode function and Selected respectively as:

[0135]

[0136]

[0137] Figure 3 , Figure 4 and Figure 5 They describe respectively , and Output system state and output reference model comparison diagram, according to Figures 3-5 It can be seen that, and Accurately tracks the reference value within 0.1 seconds. The amplitude gradually decreases over time, with slight oscillations still present at 0.5s, but overall it approaches the reference value. This demonstrates that the observer can not only reconstruct the real state but also match the dynamic characteristics of the reference model. Even with initial deviations and external disturbances, the tracking error can be quickly eliminated, ensuring that the voltage of the islanded microgrid strictly follows the preset reference and avoiding problems such as voltage deviation.

[0138] Figure 6 This describes the dynamic change curve of the adaptive parameters, used to verify the effectiveness of the adaptive mechanism. Figure 6 It can be seen that the adaptive mechanism can adjust the control gain online to counteract external disturbances to the microgrid and ensure that the control strategy can still operate stably under external disturbances.

[0139] The simulation results show that the control method of the present invention successfully solves the core problems of nonlinearity, strong coupling, and disturbance sensitivity of isolated AC / DC microgrids, and achieves the comprehensive goals of high-precision state observation, chatter-free sliding mode control, and high-quality power output, providing a feasible technical solution for the stable operation of isolated microgrids.

Claims

1. A microgrid voltage control method based on a TS fuzzy adaptive sliding mode observer, characterized in that, Includes the following steps: S1: Based on the microgrid framework and energy conversion relationship, an islanded AC / DC hybrid microgrid operation model is established through differential equations; S2: Establish an islanded AC / DC hybrid microgrid operation model for the differential equations, and construct the state-space form of the islanded AC / DC hybrid microgrid using the state-space method; S3: Based on the state-space form of the islanded AC / DC hybrid microgrid, fuzzy rules and membership functions are designed according to the coupling relationship between the AC and DC parts to establish the TS fuzzy model of the islanded AC / DC hybrid microgrid; S4: Considering external disturbances and combining the fact that the system state cannot be directly measured, establish a state observer to estimate the complete state information in real time and counteract external disturbances; S5: By estimating the error and tracking the error, two sliding mode functions are constructed so that the system output state tracks the reference model output state, thereby making the tracking error approach zero; S6: Based on the TS fuzzy model of the islanded AC / DC hybrid microgrid, a TS fuzzy adaptive sliding mode controller is established based on the state observer and two sliding mode functions, and voltage tracking control is achieved by using output feedback.

2. The microgrid voltage control method based on a TS fuzzy adaptive sliding mode observer according to claim 1, characterized in that, The islanded AC / DC hybrid microgrid operation model in step S1 is expressed as follows: ； in, and These represent the input and output voltages of the DC / DC Boost converter, respectively. This is the input current of the DC / DC Boost converter; and These represent the equivalent inductance and capacitance of the DC / DC Boost converter, respectively. and These represent the direct component and quadrature component of the input voltage of the LC filter, respectively. , and These are the first control signal, the second control signal, and the third control signal of the microgrid system, respectively. and express , and The conversion relationship between them; and These represent the inductance and resistance of the LC filter, respectively. This indicates the capacitance value of the LC filter. It is the corrected angular velocity for the microgrid frequency; and These represent the direct component and quadrature component of the output current of the LC filter, respectively. and These represent the direct component and quadrature component of the LC filter output voltage, respectively. and These represent the direct and quadrature components of the supply current in an islanded microgrid, respectively. The derivative of the direct component of the output voltage of the LC filter. The derivative of the orthogonal component of the output voltage of the LC filter. This represents the derivative of the direct component of the output current of the LC filter. This represents the derivative of the quadrature component of the output current of the LC filter. This represents the derivative of the output voltage of the DC / DC Boost converter. This represents the derivative of the input current of the DC / DC Boost converter.

3. The microgrid voltage control method based on a TS fuzzy adaptive sliding mode observer according to claim 2, characterized in that, The state-space representation of the islanded AC / DC hybrid microgrid in step S2 is as follows: definition It is a vector of state variables. It is a vector for controlling input. It is the vector of the disturbance; The system is redescribed as follows: ； Among them, the constants are composed of and These represent the parameter matrix and disturbance matrix of the control system, respectively. It is the input matrix of the control system.

4. The microgrid voltage control method based on a TS fuzzy adaptive sliding mode observer according to claim 3, characterized in that, The establishment of the fuzzy model of the islanded AC / DC hybrid microgrid TS in step S3 includes: Assumption , , and The TS fuzzy model is described by the IF-THEN rule; Rule :IF yes , yes , yes and yes THEN: ； in, Indicates the number of fuzzy rules; , , and It is the first A fuzzy set of fuzzy rules; premise variables It is considered bounded, with its upper and lower bounds being respectively... and C represents the output matrix; Through membership function Constructing a TS fuzzy model: ； in, Indicates the corresponding to the first The membership function of a linear subsystem is expressed as follows: ； in, Indicates the first The weight of each rule; Indicates the first Membership functions between the premise variables and the fuzzy set.

5. A microgrid voltage control method based on a TS fuzzy adaptive sliding mode observer according to claim 4, characterized in that, The establishment of the state observer in step S4 includes: ； in, To estimate the state, and Same dimensions; The observer gain matrix is... For the defined discontinuous vector; This is the derivative of the state observer.

6. A microgrid voltage control method based on a TS fuzzy adaptive sliding mode observer according to claim 5, characterized in that, In step S5, the two sliding mode functions are respectively related to the estimation error. sliding mode function and about tracking error sliding mode function .

7. A microgrid voltage control method based on a TS fuzzy adaptive sliding mode observer according to claim 6, characterized in that, Regarding the estimation error in step S5 sliding mode function The construction methods include: The state estimation error is defined as: ； Regarding estimation error The sliding mode function is defined as follows: ； in, It is a constant full-rank matrix and , making It is a non-singular matrix, while the observer gain matrix is... ; The sliding mode function is redefined as follows: ； Where N is the sliding surface construction coefficient matrix; This is the output estimation error.

8. A microgrid voltage control method based on a TS fuzzy adaptive sliding mode observer according to claim 7, characterized in that, Regarding the tracking error in step S5 sliding mode function The construction methods include: State tracking error is defined as: ； in, As a reference model state, output tracking error The definition of is: ； in, To output a reference model; Regarding tracking error The sliding mode function is defined as follows: ； in, It is a full-rank matrix, such that It is a non-singular matrix; It is a constant matrix, such that This becomes a Hurwitz matrix.

9. A microgrid voltage control method based on a TS fuzzy adaptive sliding mode observer according to claim 8, characterized in that, The expression of the TS fuzzy adaptive sliding mode controller in step S6 includes: ； in, It is an auxiliary control function, and its specific design is as follows: ； in, , For adaptive compensation terms, To control the sliding mode gain of the control layer, This is an adaptive law.

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