An ac-dc hybrid microgrid output decoupling control and collaborative optimization method

Abstract

The application discloses an AC-DC hybrid micro-grid output decoupling control and collaborative optimization method, comprising the following steps: establishing an AC-DC hybrid output system mathematical model to obtain an AC side model and a DC side model; performing discretization processing on the AC side model to obtain an inverter side current prediction value, and constructing a unified value function based on the current prediction value and a preset midpoint potential prediction value; selecting a switch state minimizing the unified value function through traversal optimization of all candidate switch states to obtain an AC output end control decision; generating a hysteresis control signal based on the DC side model to predict the DC output voltage variation trend, and determining the charge and discharge state of the DC output end energy storage inductor by using the hysteresis control signal; and selecting a corresponding switch state combination from redundant switch states meeting the voltage requirement of the AC output end control decision according to the charge and discharge state to adjust the DC output voltage, so that the decoupling control of the AC-DC output port is realized.

Description

Technical Field

[0001] This invention belongs to the field of power electronics and power system automation technology, and particularly relates to a method for decoupling control and collaborative optimization of AC / DC hybrid microgrid output. Background Technology

[0002] Hybrid AC / DC microgrids combine the advantages of both AC and DC microgrids, efficiently integrating distributed power sources, energy storage systems, and AC / DC loads, making them a crucial component of future smart grids. The AC and DC subgrids achieve bidirectional energy flow and coordinated operation through interconnecting converters. Therefore, the topology and control strategy of the hybrid microgrid converter directly impact system stability, power quality, and operating efficiency. Traditional hybrid microgrid power interfaces employ either a discrete architecture with independently cascaded grid-connected inverters and DC converters, or a two-stage energy conversion architecture using DC-DC boost and DC-AC inverters. With the increasing penetration of distributed power sources and the growing proportion of DC loads, these architectures are showing limitations in terms of device quantity, size, and coordinated control. The hybrid multiplexed 15-switch converter, a single-stage multi-output topology, can achieve mixed AC / DC output within the same power interface, providing a hardware foundation for coordinated control of AC / DC hybrid microgrids.

[0003] However, hybrid AC / DC microgrids based on hybrid multiplexed 15-switch converters still face several key technical challenges in practical operation. First, because power devices are multiplexed between the AC and DC outputs, the DC output cannot independently generate switching signals. Traditional time-sharing modulation strategies suffer from mutual constraints between AC and DC outputs and low DC bus voltage utilization, making it difficult to simultaneously optimize multiple objectives such as AC grid connection quality, DC voltage stability, and midpoint potential balance. Second, traditional hysteresis control strategies are susceptible to DC output voltage overflow due to controller delay and energy storage element inertia, resulting in actual voltage ripple exceeding the theoretical hysteresis width. Furthermore, conventional control methods often require complex PR regulator designs and SVPWM modulation algorithms, increasing system implementation complexity and hindering the improvement of grid current quality and active midpoint potential balancing performance. Therefore, a novel control method is urgently needed that can simplify the modulation structure while achieving decoupled control of the AC and DC output ports, improving power quality, and ensuring stable system operation. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a method for decoupling control and collaborative optimization of AC / DC hybrid microgrid output, thereby resolving the issues present in the prior art.

[0005] To achieve the above objectives, this invention provides a method for decoupling control and collaborative optimization of AC / DC hybrid microgrid output, comprising: A mathematical model of an AC / DC hybrid output system with a hybrid multiplexed 15-switch converter as the unified power interface is established, and the AC side model and DC side model are obtained. The AC side model is discretized to obtain the inverter side current prediction value. A unified value function is constructed based on the current prediction value and the preset midpoint potential prediction value. By traversing and optimizing all candidate switching states, the switching state that minimizes the unified value function is selected to obtain the AC output control decision. Based on the DC-side model, the trend of DC output voltage change is predicted to generate a hysteresis control signal, and the charging and discharging state of the energy storage inductor at the DC output terminal is determined using the hysteresis control signal. Based on the charging and discharging state, a corresponding combination of switching states is selected from the redundant switching states that meet the control decision voltage requirements of the AC output terminal, and the DC output voltage is adjusted to achieve decoupling control of the AC and DC output ports.

[0006] Optionally, the process of discretizing the AC side model to obtain the inverter side current prediction value includes: The inverter-side current prediction equation is obtained by discretizing the AC-side model using the forward Euler method. Substituting the current sample value of the inverter side and the voltage vector corresponding to the candidate switch state at the current moment into the current prediction equation, we obtain the current prediction value of the inverter side at the next moment.

[0007] Optionally, the process of constructing a unified value function based on the predicted current value and the preset predicted midpoint potential value to select the optimal switching state includes: A midpoint potential prediction model is established based on the current values ​​of the capacitor voltages on the upper and lower sides of the DC bus and the relationship between the midpoint current. Substitute the current capacitor voltage value and the switching function corresponding to the candidate switch state into the midpoint potential prediction model to obtain the predicted values ​​of the upper and lower capacitor voltages at the next moment. The current tracking error term is obtained based on the deviation between the predicted current value and the reference value, and the midpoint potential balance error term is obtained based on the deviation between the predicted upper and lower capacitor voltage values. The current tracking error term and the weighted midpoint potential balance error term are added together to obtain a unified value function. Substitute the predicted current and capacitor voltage values ​​corresponding to each candidate switching state into the unified value function to calculate the function value, and select the switching state that minimizes the function value as the optimal switching state output.

[0008] Optionally, the expression for the unified value function is: ; In the formula, ω This is the midpoint potential balance weighting coefficient; JTo unify the value function; The value function of the midpoint potential prediction model; The value function for the AC output prediction model.

[0009] Optionally, the process of generating a hysteresis control signal based on the predicted DC output voltage change trend using the DC-side model, and using the hysteresis control signal to determine the charging and discharging state of the energy storage inductor at the DC output terminal, includes: The voltage change rate is calculated based on the DC output voltage sample values ​​at the current moment and the previous moment, and the predicted DC output voltage value at the next moment is obtained based on the voltage change rate and the sampling period. The hysteresis control signal is obtained by comparing the deviation between the predicted DC output voltage value and the reference DC output voltage value with the hysteresis half-bandwidth. The charging and discharging state of the DC output energy storage inductor is determined based on the hysteresis control signal.

[0010] Optionally, the expression for obtaining the predicted DC output voltage value at the next moment based on the voltage change rate and sampling period is as follows: ; In the formula, α For prediction coefficients, for k Predicted voltage value at time +1 v ( k )for k The rate of change of DC output voltage at time t. v dc ( k )for k The DC output voltage sampling value at any given time. T s The sampling period.

[0011] Optionally, the expression for the hysteresis control signal is obtained by comparing the deviation between the predicted DC output voltage and the reference DC output voltage with the hysteresis half-bandwidth: ; In the formula, This is the reference value for the DC output voltage. h It is the hysteresis half bandwidth; S dc ( k )for k The charging and discharging indicator of the energy storage inductor at the DC output terminal is constantly displayed. for k Predicted voltage value at time +1.

[0012] The present invention also provides a computer, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method described thereon.

[0013] The present invention also provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described thereon.

[0014] Compared with the prior art, the present invention has the following advantages and technical effects: This invention proposes a decoupling control and collaborative optimization method for the output of a hybrid AC / DC microgrid. By establishing a system mathematical model with a hybrid multiplexed 15-switch converter as the unified power interface, a unified value function is used on the AC side to fuse current tracking and midpoint potential balance as dual objectives. The optimal switching state is obtained through ergonomic optimization. Without requiring complex PR regulators and SVPWM modulation algorithms, rapid current tracking and active midpoint potential balance on the inverter side are achieved, with grid-connected current harmonic distortion rate controlled within 5% and dynamic transition smooth. For the DC side, hysteresis control based on voltage change rate prediction is employed, predicting the next... By predicting voltage limits in advance and switching the inductor charging and discharging state before the voltage exceeds the limit, the voltage overshoot problem caused by controller delay and energy storage inertia in traditional hysteresis control is effectively suppressed, making the DC voltage ripple approach the theoretical hysteresis width. On this basis, the redundant switching states of the AC output terminal are used to independently adjust the DC output voltage, avoiding mutual constraints between AC and DC outputs and realizing decoupled control of AC and DC ports. This ensures that the DC output voltage remains stable under wide-range adjustment of AC grid current and large-range variation of DC load. The system has a simple overall structure, fast dynamic response, and strong robustness, and has good engineering practical value. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of an AC / DC hybrid microgrid output decoupling control and collaborative optimization method according to an embodiment of the present invention; Figure 2 This is a converter topology diagram according to an embodiment of the present invention; Figure 3 This is a flowchart of the AC output control strategy according to an embodiment of the present invention; Figure 4 This is a flowchart of the DC output control strategy according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the simulation results of the AC output terminal grid-connected voltage and current according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the simulation results of the AC output grid-connected current tracking capability according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the simulation results of the harmonic distortion rate of the grid-connected current at the AC output terminal according to an embodiment of the present invention. Figure 8 This is a schematic diagram of the simulation results of the capacitor voltages on the upper and lower sides of the DC bus in an embodiment of the present invention; Figure 9 This is a schematic diagram of the simulation results of the DC output voltage in an embodiment of the present invention; Figure 10 This is a schematic diagram of the simulation results of the dynamic response of the harmonic distortion rate of the grid-connected current at the AC output terminal according to an embodiment of the present invention. Figure 11 This is a schematic diagram of the simulation results of the dynamic response of the DC output voltage in an embodiment of the present invention; Figure 12 This is a schematic diagram showing the experimental results of the AC output terminal grid-connected voltage and current in an embodiment of the present invention; Figure 13 This is a schematic diagram of the experimental results of DC bus capacitor voltage and midpoint potential voltage in an embodiment of the present invention; Figure 14 This is a schematic diagram of the experimental results of the DC output voltage in an embodiment of the present invention. Detailed Implementation

[0016] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0017] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0018] Example 1 This invention discloses a method for decoupling control and collaborative optimization of AC / DC hybrid microgrid outputs. The method includes: establishing a mathematical model of the AC / DC hybrid output system using a hybrid multiplexed 15-switch converter as the unified power interface; for the AC output, establishing a bi-objective finite set model predictive current control model considering inverter-side current tracking accuracy and midpoint potential balance; for the DC output, establishing a hysteresis control model based on DC voltage change rate prediction; and collaboratively selecting switching states according to the effective operating state of the converter, adjusting the DC output voltage through redundant switching states while meeting the required voltage at the AC output, thereby achieving decoupling control and collaborative optimization of the AC / DC output ports. This invention can improve the DC bus voltage utilization rate of the hybrid microgrid converter, reduce modulation complexity, improve the grid-connected current quality at the AC output, suppress DC output voltage ripple, and achieve active midpoint potential balance.

[0019] like Figure 1 As shown, this embodiment provides a method for decoupling control and collaborative optimization of AC / DC hybrid microgrid output, including the following steps: (1) Establish a mathematical model of the AC / DC hybrid output system with a hybrid multiplexed 15-switch converter as the unified power interface, and obtain the AC side model and the DC side model; the specific implementation process includes: Establish an exchange output end αβ Mathematical model in coordinate system: (1) in, i α , i β These are the inverter-side currents. α、β Axial components; u α , u β These are the inverter-side voltages. α、β Axial components; u Cα , u Cβ These are the voltages of the filter capacitors at the AC output terminals. α、β Axial components; i gα , i gβ These are the grid-side currents. α、β Axial components; u gα , u gβ These are the grid-side voltages. α、β Axial components.

[0020] Establish an equivalent Buck buck chopper circuit model at the DC output terminal: (2) in, L dco , C dco These are the DC output filter inductor and capacitor, respectively. i L dco is the DC output branch current; D b The duty cycle of the switch transistor in the Buck circuit; U dc This is the DC bus voltage; v dc This is the DC output voltage; R load It is a DC output load.

[0021] (2) For the AC output terminal, a bi-objective finite set model predictive current control model is established, considering the inverter-side current tracking accuracy and the neutral point potential balance. Specifically, this includes the following steps: Step 1: Discretize the AC side model to obtain the inverter side current prediction value, including: using the forward Euler method to discretize the AC side model to obtain the inverter side current prediction equation; substituting the current sample value of the inverter side and the voltage vector corresponding to the candidate switch state at the current moment into the current prediction equation to obtain the inverter side current prediction value at the next moment.

[0022] The specific implementation process includes: discretizing the continuous model shown in equation (1) using the forward Euler method to obtain the AC output prediction equation: (3) in, i P α( k +1) i P β( k +1) are respectively k The predicted inverter-side current component at time +1; i α ( k ), i β ( k ) are respectively k Inverter-side current component at any given moment; u α ( k ), u β ( k ) are respectively k Inverter-side voltage components at any given moment; u Cα ( k ),u Cβ ( k ) are respectively k The voltage component of the filter capacitor at the AC output terminal at all times; R i , L i These are the internal resistance and inductance of the inverter-side reactor, respectively. T s The sampling period; The process of constructing a unified value function based on the predicted current value and the preset predicted midpoint potential value to select the optimal switching state includes: establishing a midpoint potential prediction model based on the current values ​​of the upper and lower capacitor voltages on the DC bus and the relationship between the midpoint current; substituting the current capacitor voltage value and the switching function corresponding to the candidate switching state into the midpoint potential prediction model to obtain the predicted values ​​of the upper and lower capacitor voltages at the next moment; obtaining the current tracking error term based on the deviation between the predicted current value and the reference value, obtaining the midpoint potential balance error term based on the deviation between the predicted upper and lower capacitor voltage values, adding the current tracking error term and the weighted midpoint potential balance error term to obtain the unified value function; substituting the predicted current value and the predicted capacitor voltage value corresponding to each candidate switching state into the unified value function to calculate the function value, and selecting the switching state that minimizes the function value as the optimal switching state output. The specific implementation process includes steps 2-4.

[0023] Step 2: Using the inverter-side current as the control variable, construct the value function of the AC output prediction model, i.e., the current tracking error term: (4) in, i α( k +1) i β( k +1) are respectively k The inverter-side current reference value component at time +1.

[0024] Step 3: Establish the value function of the midpoint potential prediction model with the objective of minimizing the voltage difference between the upper and lower capacitors: Current flowing through the midpoint of the DC bus i np for: (5) in, x ∈{a,b,c}; S x2 , S x3 This is the state of the switch used to generate a zero level, and its value is 0 or 1; According to Kirchhoff's current law, the midpoint current...i np It can also be expressed as: (6) in, C 1. C 2 represents the upper and lower capacitors of the DC bus, respectively, and their values ​​are both DC bus capacitances. C dc Half of; i C1 , i C2 respectively flowing through C 1. C The current of 2; u C1 , u C2 They are respectively C 1. C 2 voltage; DC bus total voltage u dc The change is relatively slow and can be approximated as a constant value within one sampling period, that is: (7) Substituting equation (7) into equation (6) and discretizing it, we get: (8) in, x ∈{a,b,c}; u P C 1( k +1) u P C 2( k +1) are respectively k Predicted values ​​of the upper and lower capacitor voltages at time +1; uC 1( k ), uC 2( k ) are respectively k The voltage of the upper and lower capacitors at any given time; i x ( k )for k Inverter side x Phase current; Different candidate switch states correspond to different midpoint currents, which in turn have different regulatory effects on the voltage of the upper and lower capacitors; this can be predicted using equation (8). k The voltage values ​​of the upper and lower capacitors at time +1 are used to achieve active balance control of the midpoint potential. With the objective of minimizing the voltage difference between the upper and lower capacitors, the value function of the midpoint potential prediction model, i.e., the midpoint potential balance error term, is: (9) Step 4: Establish a unified value function that comprehensively considers the inverter-side current tracking accuracy and the midpoint potential balance, and select the optimal switching state; Combining equations (4) and (9), a unified value function for the prediction model that comprehensively considers the accuracy of AC output current tracking and the balance of midpoint potential is established. J for: (10) in, ω This is the midpoint potential balance weighting coefficient; Within each sampling period, the controller iterates through and predicts all 27 switching states, and finally selects... J The minimum corresponding switching state is used as the optimal control decision, thereby achieving coordinated optimization of inverter-side current control and midpoint potential balance.

[0025] (3) For the DC output terminal, a hysteresis control model based on the prediction of DC voltage change rate is established. That is, the process of generating a hysteresis control signal based on the prediction of the DC output voltage change trend based on the DC side model, and using the hysteresis control signal to determine the charging and discharging state of the energy storage inductor at the DC output terminal includes: calculating the voltage change rate based on the DC output voltage sample values ​​at the current time and the previous time, obtaining the predicted value of the DC output voltage at the next time based on the voltage change rate and the sampling period; comparing the deviation between the predicted value of the DC output voltage and the reference value of the DC output voltage and the hysteresis half bandwidth to obtain the hysteresis control signal; and determining the charging and discharging state of the energy storage inductor at the DC output terminal based on the hysteresis control signal.

[0026] Hysteresis control signals are generated based on the DC-side model to predict the DC output voltage variation trend, and these signals are used to determine the charging and discharging state of the energy storage inductor at the DC output terminal; specifically including: k Rate of change of DC output voltage at time 1 v ( k )for: (11) in, v dc ( k )for k The DC output voltage sampling value at any given time; Assuming the rate of voltage change remains constant within one sampling period, we can obtain k The predicted voltage value at time +1 is: (12) in, α The prediction coefficient has a value range of [0,1]. A value of 1 indicates the strongest prediction effect, while a value of 0 indicates a degradation to the current sampled value of the traditional hysteresis loop. Predictive hysteresis control As the judgment variable, the control law is constructed as follows: (13) in, This is the reference value for the DC output voltage. h It is the hysteresis half bandwidth; S dc ( k )for k The DC output terminal energy storage inductor charging and discharging flag is set. A value of 1 indicates the charging state, and a value of 0 indicates the discharging state. Based on the predicted value It can predict the voltage overshoot trend in advance and ensure that the inductor charging and discharging state is switched before the actual voltage overshoot, thereby suppressing the voltage overshoot caused by sampling and control delay and energy storage inertia, and making the voltage ripple approach the theoretical hysteresis width.

[0027] (4) Select the switching state in coordination according to the effective working state of the converter. Under the premise of meeting the required voltage of the AC output terminal, adjust the DC output terminal voltage through redundant switching state to realize the decoupling control and coordinated optimization of AC and DC output ports.

[0028] Based on the charging and discharging state, a corresponding combination of switching states is selected from the redundant switching states that meet the control decision voltage requirements of the AC output terminal, and the DC output voltage is adjusted to achieve decoupling control of the AC and DC output ports; specifically including: Since the AC and DC output terminals share power devices, the DC output terminal cannot generate a switching signal independently. Traditional time-division modulation strategies suffer from problems such as mutual constraints between AC and DC outputs and low utilization of DC bus voltage. According to the hybrid multiplexed 15-switch converter topology, under the premise of meeting the voltage requirements of the AC output terminal, there is a redundant switching state that can adjust the DC output terminal voltage.

[0029] Furthermore, in order to verify the feasibility and universality of the proposed DC hybrid microgrid output decoupling control and collaborative optimization method, this embodiment takes AC output of 380V and DC output of 150V as an example to simulate and experimentally verify the steady-state output and dynamic regulation capability of AC-DC hybrid microgrid based on hybrid multiplexing type 15-switch converter. The results show that after adopting the proposed control strategy, the actual current at the AC output terminal can quickly track the given command, the overshoot during the dynamic adjustment process is small, the steady-state process is basically free of steady-state error, and the harmonic distortion rate of the grid-connected current is always kept within 5%, which meets the grid connection requirements; the capacitor voltages on the upper and lower sides of the DC bus remain symmetrically distributed, and the midpoint potential does not show a continuous deviation; the DC output terminal voltage can be stabilized near the given command, with small overall fluctuation amplitude, and is not affected by changes in the given value of the AC output terminal grid-connected current.

[0030] like Figure 2 The diagram shows the topology of a hybrid multiplexed 15-switch converter. Figure 2 middle, U dc This is the DC bus voltage; C dc For DC bus capacitors; O The midpoint of the DC bus; u a , u b , u c These are the three-phase voltages on the inverter side; i a , i b , i c These are the three-phase currents on the inverter side; R i , L i These are the internal resistance and inductance of the inverter-side reactor, respectively. C f For AC output filtering capacitor; u Ca , u Cb , u Cc These are the three-phase voltages of the filter capacitors at the AC output terminals; i Ca , i Cb , i Cc These are the three-phase currents of the AC output filter capacitor; R g , L g These are the internal resistance and inductance of the grid-side reactor, respectively. u ga , u ga , u gc These are the three-phase voltages on the grid side; i ga , i gb , i gc These are the three-phase currents on the grid side; L dco , C dco These are the DC output filter inductor and capacitor, respectively. i x , i y, i z These are the currents of each parallel branch at the DC output terminal; v dc This is the DC output bus voltage.

[0031] according to Figure 2 The converter topology shown employs a finite set model predictive current control strategy, incorporating inverter-side current tracking error and midpoint potential deviation into a unified value function. It iteratively predicts 27 switching states at the AC output, ultimately selecting the switching state corresponding to the minimum value function as the optimal control decision. This achieves coordinated optimization of inverter-side current control and midpoint potential balance. For the algorithm flowchart, please refer to [link to algorithm details]. Figure 3 .

[0032] In implementation Figure 3 Based on the control of the AC output terminal shown, the DC output terminal adopts a hysteresis control strategy based on voltage change rate prediction. The DC voltage over-limit trend is judged in advance according to the voltage prediction value and hysteresis control is performed. Since the AC output terminal and the DC output terminal share the same power device, there is a redundant switching state of adjustable DC output terminal voltage under the premise of meeting the voltage required by the AC output terminal, as shown in Table 1.

[0033] Table 1 When the predictive hysteresis control strategy needs to enter the energy storage inductor discharge state because the DC output voltage is higher than the upper hysteresis limit ( S dc =0), prioritize the switching state among states I, II, and III; when the output voltage is lower than the lower boundary of the hysteresis loop, it needs to enter the energy storage inductor charging state ( S dc =1), prioritize the switching states in states IV and V. DC output voltage regulation is achieved through redundant switching states, realizing the decoupling and coordinated operation of AC / DC hybrid outputs. The algorithm flow is as follows: Figure 4 As shown.

[0034] Figure 5 The simulation results show the grid-connected voltage and current at the AC output terminal. After the system is put into operation, it can enter the steady-state process within one power frequency cycle, and the AC output terminal achieves grid connection with unity power factor. When the current setpoint changes by 0.1 s, the grid-connected voltage always maintains a sinusoidal waveform with stable amplitude and phase, and the grid-connected current quickly follows the given command and enters a new steady-state operating state with a smooth transition process. The above results show that the proposed control method has good control performance in both steady-state and dynamic adjustment processes.

[0035] Figure 6The simulation results show the grid-connected current tracking capability of the AC output terminal. The actual current can quickly track the given command, the overshoot is small during the dynamic adjustment process, and there is basically no steady-state error during the steady-state process. The proposed control method has good tracking performance.

[0036] Figure 7 The simulation results show the harmonic distortion rate of the grid-connected current at the AC output terminal; the harmonic distortion rate of the grid-connected current is only 1.68%, which meets the grid connection requirements.

[0037] Figure 8 The simulation results show the voltages of the upper and lower capacitors on the DC bus. The voltages of the upper and lower capacitors remain relatively close, and the midpoint potential fluctuates slightly around the equilibrium point without any sustained deviation. These results indicate that establishing a unified value function considering both inverter-side current tracking accuracy and midpoint potential balance in the finite set model predictive current control strategy can achieve synergistic optimization of the midpoint potential balance without adding additional control loops.

[0038] Figure 9 The simulation results show the DC output voltage. The DC output voltage can quickly track and stabilize near the given value, unaffected by changes in the AC output grid current. This result demonstrates that the proposed control method can achieve precise regulation of the DC output voltage while ensuring the AC output grid connection quality and midpoint potential balance, thus realizing decoupled control of the AC and DC output ports.

[0039] Figure 10 The simulation results show the dynamic response of the grid-connected current harmonic distortion rate at the AC output terminal. When the DC output terminal load is constant, as the grid-connected current setpoint decreases from 50A to 30A, the grid-connected current harmonic distortion rate increases from 1.7% to 3.0%, with a smooth overall change and consistently remaining below 5%. This indicates that the proposed control strategy can maintain good harmonic suppression capability over a wide range of setpoint current adjustment. When the grid-connected current setpoint remains constant, as the DC output terminal load changes from 1Ω to 10Ω, the fluctuation amplitude of the grid-connected current harmonic distortion rate is controlled within ±0.2%, without significant amplification or abrupt changes, demonstrating that the proposed control method has strong robustness to changes in DC output terminal load parameters.

[0040] Figure 11 The simulation results show the dynamic response of the DC output voltage. Under the wide-range coordinated change of the grid current setpoint from 50A to 30A and the DC output load from 1Ω to 10Ω, the DC output voltage remains stable near the setpoint of 150V. This indicates that under the proposed control method, the DC output voltage has good decoupling characteristics from the changes in the DC output load and the grid current regulation.

[0041] Figure 12The experimental results show the grid-connected voltage and current at the AC output terminal. The AC output terminal can achieve in-phase operation of the grid-connected voltage and current. During dynamic adjustment, the grid-connected voltage remains essentially constant, and the grid-connected current can track the given command well and enter a new steady-state process. The current harmonic distortion rate is 1.83%. The results indicate that the proposed control method, while eliminating the complex PR regulator design and SVPWM modulation algorithm of traditional control strategies, still ensures good grid-connected quality at the AC output terminal.

[0042] Figure 13 The experimental results show the DC bus capacitor voltage and midpoint potential voltage. The capacitor voltages on the upper and lower sides of the DC bus can maintain a symmetrical distribution, the midpoint potential fluctuation amplitude is only about 2V, and no continuous deviation phenomenon is observed. This verifies that the proposed control method has a good midpoint potential deviation suppression effect.

[0043] Figure 14 The results are from the DC output voltage experiment; the DC output voltage can be stabilized near the given command and is not affected by changes in the given value of the AC output grid current.

[0044] This embodiment addresses the problems of device redundancy and complex coordination control caused by cascading multiple converters in traditional AC / DC hybrid microgrids. Using a hybrid multiplexed 15-switch converter as a unified power interface, it proposes a method for output decoupling control and collaborative optimization of AC / DC hybrid microgrids. Through theoretical modeling, simulation, and hardware experiments, the following conclusions are obtained: 1) The proposed collaborative control strategy achieves decoupled control and collaborative optimization of AC and DC outputs. The AC output adopts a finite set model predictive current control strategy, which incorporates inverter-side current tracking and midpoint potential balance into a unified value function; the DC output introduces hysteresis control based on voltage change rate prediction, and independently adjusts the DC voltage through redundant switch state mapping.

[0045] 2) The finite set model predictive current control strategy at the AC output end not only eliminates the complex PR regulator design and SVPWM modulation algorithm in traditional control strategies, but also further improves the grid connection quality and midpoint potential balance performance at the AC output end.

[0046] 3) The DC output predictive hysteresis control strategy can suppress the voltage overshoot problem caused by controller delay and energy storage inertia in traditional hysteresis control by predicting the DC voltage change trend in advance and switching the inductor charging and discharging state in time.

[0047] 4) Simulation and experimental results verify the robustness and engineering applicability of the control strategy. Under the condition that the grid-connected current setpoint and the DC load change in tandem, the system always maintains good AC grid connection quality and DC voltage stability; during dynamic adjustment, the grid-connected current transition is smooth, the grid-connected voltage is undistorted, and the DC output voltage remains constant.

[0048] The present invention also provides a computer, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method described thereon.

[0049] The present invention also provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described thereon.

[0050] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for decoupling control and collaborative optimization of AC / DC hybrid microgrid output, characterized in that, Includes the following steps: A mathematical model of an AC / DC hybrid output system with a hybrid multiplexed 15-switch converter as the unified power interface is established, and the AC side model and DC side model are obtained. The AC side model is discretized to obtain the inverter side current prediction value. A unified value function is constructed based on the current prediction value and the preset midpoint potential prediction value. By traversing and optimizing all candidate switching states, the switching state that minimizes the unified value function is selected to obtain the AC output control decision. Based on the DC-side model, the trend of DC output voltage change is predicted to generate a hysteresis control signal, and the charging and discharging state of the energy storage inductor at the DC output terminal is determined using the hysteresis control signal. Based on the charging and discharging state, a corresponding combination of switching states is selected from the redundant switching states that meet the control decision voltage requirements of the AC output terminal, and the DC output voltage is adjusted to achieve decoupling control of the AC and DC output ports.

2. The AC / DC hybrid microgrid output decoupling control and collaborative optimization method according to claim 1, characterized in that, The process of discretizing the AC side model to obtain the inverter side current prediction value includes: The inverter-side current prediction equation is obtained by discretizing the AC-side model using the forward Euler method. Substituting the current sample value of the inverter side and the voltage vector corresponding to the candidate switch state at the current moment into the current prediction equation, we obtain the current prediction value of the inverter side at the next moment.

3. The AC / DC hybrid microgrid output decoupling control and collaborative optimization method according to claim 2, characterized in that, The process of constructing a unified value function based on the predicted current value and the preset midpoint potential value to select the optimal switching state includes: A midpoint potential prediction model is established based on the current values ​​of the capacitor voltages on the upper and lower sides of the DC bus and the relationship between the midpoint current. Substitute the current capacitor voltage value and the switching function corresponding to the candidate switch state into the midpoint potential prediction model to obtain the predicted values ​​of the upper and lower capacitor voltages at the next moment. The current tracking error term is obtained based on the deviation between the predicted current value and the reference value, and the midpoint potential balance error term is obtained based on the deviation between the predicted upper and lower capacitor voltage values. The current tracking error term and the weighted midpoint potential balance error term are added together to obtain a unified value function. Substitute the predicted current and capacitor voltage values ​​corresponding to each candidate switching state into the unified value function to calculate the function value, and select the switching state that minimizes the function value as the optimal switching state output.

4. The AC / DC hybrid microgrid output decoupling control and collaborative optimization method according to claim 3, characterized in that, The expression for the unified value function is: ； In the formula, ω This is the midpoint potential balance weighting coefficient; J To unify the value function; The value function of the midpoint potential prediction model; The value function for the AC output prediction model.

5. The AC / DC hybrid microgrid output decoupling control and collaborative optimization method according to claim 1, characterized in that, The process of generating a hysteresis control signal based on the DC-side model to predict the DC output voltage change trend, and using the hysteresis control signal to determine the charging and discharging state of the energy storage inductor at the DC output terminal, includes: The voltage change rate is calculated based on the DC output voltage sample values ​​at the current moment and the previous moment, and the predicted DC output voltage value at the next moment is obtained based on the voltage change rate and the sampling period. The hysteresis control signal is obtained by comparing the deviation between the predicted DC output voltage value and the reference DC output voltage value with the hysteresis half-bandwidth. The charging and discharging state of the DC output energy storage inductor is determined based on the hysteresis control signal.

6. The AC / DC hybrid microgrid output decoupling control and collaborative optimization method according to claim 5, characterized in that, The expression for predicting the DC output voltage at the next moment based on the voltage change rate and sampling period is as follows: ； In the formula, α For prediction coefficients, for k Predicted voltage value at time +1 v ( k )for k The rate of change of DC output voltage at time t. v dc ( k )for k The DC output voltage sampling value at any given time. T s The sampling period.

7. The AC / DC hybrid microgrid output decoupling control and collaborative optimization method according to claim 6, characterized in that, The expression for the hysteresis control signal is obtained by comparing the deviation between the predicted DC output voltage and the reference DC output voltage with the hysteresis half-bandwidth: ； In the formula, This is the reference value for the DC output voltage. h It is the hysteresis half bandwidth; S dc ( k )for k The charging and discharging indicator of the energy storage inductor at the DC output terminal is constantly displayed. for k Predicted voltage value at time +1.

8. A computer comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method as described in claim 1.

9. A storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in claim 1.

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