Micro-grid electric energy quality optimization control method and device based on event trigger mechanism

Abstract

The invention discloses a microgrid power quality optimization control method and device based on an event trigger mechanism, and the method comprises the steps: 1, generating a sinusoidal voltage through droop control, and solving a bus voltage through virtual impedance control; 2, extracting harmonic current of the power distribution network, and constructing a virtual impedance expression; step 3, constructing a leader-follower distributed controller based on time triggering according to the extracted harmonic current of the power distribution network and the communication network of the micro-grid; and 4, determining a trigger condition of the leader-follower distributed controller, triggering the leader-follower distributed controller when the trigger condition is satisfied, generating virtual impedance, and controlling each inverter to perform distributed cooperative control based on harmonic power equalization. According to the invention, the inverter can be controlled to absorb different harmonic powers, and the electric energy quality of the micro-grid is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of microgrid control, and particularly to a method and device for optimizing the power quality control of a microgrid based on an event triggering mechanism. Background Art

[0002] With the access of a large number of asymmetric loads and nonlinear loads in the distribution network, the power quality problem has become increasingly prominent. In the operation of a microgrid, the unreasonable distribution of reactive power and harmonic power among inverters will seriously affect the efficient and stable operation of the system. The coordinated control of multiple inverters is the key to ensuring the reliable operation of the microgrid, which requires the inverters to reasonably share the load power according to the rated power to avoid overload.

[0003] The existing technologies mainly focus on achieving accurate power distribution among inverters, but ignore the utilization of the remaining capacity of the inverters and fail to improve the power quality of the microgrid through this resource. On the premise of preventing inverter overload, how to make the inverters absorb as much harmonic power as possible while reducing the communication burden and data transfer volume of the entire control system is a problem that needs to be considered. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects in the prior art that the access of a large number of asymmetric loads to the distribution network leads to the decline of the power quality of the distribution network, and the communication burden is heavy during the control of the inverters, affecting the overall operation efficiency of the distribution network, and to provide a method and device for optimizing the power quality control of a microgrid based on an event triggering mechanism.

[0005] The purpose of the present invention is realized by the following technical solutions: A method for optimizing the power quality control of a microgrid based on an event triggering mechanism includes the following steps: Step 1, generating a sinusoidal voltage by using droop control and solving for the bus voltage by using virtual impedance control; Step 2, extracting the harmonic current of the distribution network and constructing a virtual impedance expression based on the relationship between the bus voltage and the harmonic current; Step 3, constructing an event-triggered leader-follower distributed controller according to the fundamental component of the sinusoidal voltage, the extracted harmonic current of the distribution network, and the communication network of the microgrid, and taking the output of the virtual impedance expression as the state variable input; Step 4, determining the triggering condition of the leader-follower distributed controller. When the triggering condition is satisfied, the leader-follower distributed control is triggered to generate a virtual impedance, and at the same time, each inverter is controlled for distributed cooperative control based on harmonic power equalization.

[0006] In step 1 of this solution, as the logical starting point of the method, a basic voltage generation mechanism for the microgrid is constructed through droop control and virtual impedance control, providing necessary preconditions for subsequent harmonic processing, controller design, and coordinated control. In step 2, the harmonic current is converted into a virtual impedance expression through mathematical modeling, providing executable control parameters for the distributed control in steps 3 - 4, forming a technical link of "problem modeling - control execution". The design of this solution adopts an event-triggered leader-follower microgrid harmonic equalization control strategy, taking into account both harmonic equalization and bus voltage governance, and adopting an event-triggered mechanism to effectively reduce the communication burden between inverters; at the same time, unnecessary data transmission is avoided, maximizing the power quality of the microgrid. By setting the value of the virtual leader node, the magnitude of the harmonic power absorbed by the inverter can be controlled, thereby improving the power quality, which is applicable to the requirements of the actual microgrid.

[0007] Preferably, in step 1, droop control is used to generate a sinusoidal voltage, specifically: Detect the actual output active power and reactive power of the inverter as the input signals for droop control; Multiply the deviations of the actual output active power and reactive power from the rated power by the corresponding droop coefficients respectively to obtain the frequency deviation and voltage amplitude deviation; Superimpose the frequency deviation and voltage amplitude deviation on the rated values respectively to obtain the actual frequency and voltage amplitude; Generate a sinusoidal voltage signal based on the actual frequency and voltage amplitude.

[0008] Preferably, in step 2, the method for extracting the harmonic current of the distribution network is to use the method based on the cross cancellation feedback of the second-order generalized integral orthogonal signal generator to realize the separation and extraction of different-order harmonic currents.

[0009] Preferably, in step 2, the process of constructing the virtual impedance expression is as follows: After the separation and extraction of different-order harmonic currents are completed, multiply the harmonic current by an impedance coefficient to obtain the harmonic voltage reference signal output by the distributed power source inverter, and then obtain the virtual impedance of the distributed power source inverter at the harmonic frequency.

[0010] Preferably, step 3 is specifically as follows: Construct a state space model of the system harmonic power, regard each inverter as an agent, and define the error between the agent and the virtual leader node. When there is a spanning tree in the communication network, the agent state can converge to the leader node; Introduce an event-triggered mechanism, set the time-varying error of each agent, and update the control input of the agent when the trigger condition is met to avoid continuous communication; Design a control protocol to integrate the latest trigger status of itself and its neighbors for coordinated updates.

[0011] Preferably, in the design control protocol, in the process of integrating the latest trigger status of itself and its neighbors for collaborative updating, a consensus variable is introduced to integrate the harmonic power and the remaining capacity into a single variable. When the remaining capacity of the inverter decreases, the consensus variable automatically increases, triggering the control system to reduce the harmonic absorption and prevent overload.

[0012] Preferably, in step 3, the Lyapunov method is also used to prove the stability of the leader-follower distributed controller control strategy.

[0013] Preferably, in step 4, the triggering condition of the leader-follower distributed controller is determined by the stability analysis results and execution conditions. When the stability value reaches the trigger threshold, the controller samples and outputs, thereby updating the value stored in the controller triggered by the last event.

[0014] The microgrid power quality optimization control device based on event triggering mechanism includes: Voltage generation and solution module, used to generate sinusoidal voltage using droop control and solve bus voltage using virtual impedance control; Harmonic current processing module, used to extract the harmonic current of the distribution network and construct a virtual impedance expression; A controller building module is used to build an event-triggered leader-follower distributed controller based on the extracted harmonic current of the distribution network and the communication network of the microgrid; The trigger and control module is used to determine the trigger conditions of the leader-follower distributed controller. When the trigger conditions are met, the leader-follower distributed control is triggered to generate virtual impedance. At the same time, the distributed collaborative control of each inverter is controlled based on harmonic power sharing.

[0015] Preferably, the trigger and control module includes: Stability analysis unit, used to prove the stability of the control strategy using the Lyapunov method and determine the relationship between the trigger threshold and the system parameters; The threshold dynamic adjustment unit is used to adjust the trigger threshold in real time according to the frequency fluctuation and voltage deviation of the microgrid, balancing the control accuracy and communication overhead.

[0016] The beneficial effect of the present invention is that the event trigger control of the present invention will only transmit data when the trigger condition is met, that is, a certain threshold is reached, which effectively avoids useless data flow and reduces a lot of unnecessary calculations for the entire optimization management method.

[0017] The control variable in the adopted consistency control strategy introduces the remaining capacity. By setting the value of the virtual leader node, the situation of inverter overload can be well avoided, and thus the inverter can also be well protected.

[0018] Since the virtual leader node is a virtual value in this control framework and can be flexibly adjusted, by adjusting the values of different virtual leader nodes, the inverter can absorb different harmonic powers, improving the power quality of this microgrid. Brief Description of the Drawings

[0019] Figure 1 is a flowchart of the present invention; Figure 2 is a block diagram of the power droop controller; Figure 3 is a schematic diagram of the virtual impedance control principle of the inverter; Figure 4 is a schematic diagram of the harmonic current extraction method based on SOGI-QSG cross cancellation; Figure 5 Schematic diagram of microgrid simulation; Figure 6 is a schematic diagram of the ratio of the harmonic power of each inverter to the remaining capacity; Figure 7 is a schematic diagram of the trigger moment of the controller; Figure 8 is a schematic diagram of the bus voltage distortion rate before and after applying the control. Detailed Embodiments

[0020] Now, the exemplary embodiments will be described more fully with reference to the accompanying drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete, and the concept of the exemplary embodiments will be fully conveyed to those skilled in the art.

[0021] In addition, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of this application. However, those skilled in the art will realize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, well-known methods, devices, implementations, or operations are not shown or described in detail to avoid obscuring aspects of this application.

[0022] The block diagrams shown in the drawings are only functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0023] The flowcharts shown in the drawings are only illustrative descriptions, and do not necessarily include all contents and operations / steps, nor are they necessarily executed in the described order. For example, some operations / steps can be decomposed, while some operations / steps can be combined or partially combined. Therefore, the actual execution order may change according to the actual situation.

[0024] Embodiment: A microgrid power quality optimization control method based on an event-triggered mechanism, such as Figure 1 shown, includes the following steps: Step 1, use droop control to generate a sinusoidal voltage, and use virtual impedance control to solve for the bus voltage; Step 2, extract the harmonic current of the distribution network, and construct a virtual impedance expression based on the relationship between the bus voltage and the harmonic current; Step 3, according to the fundamental component of the sinusoidal voltage, the extracted harmonic current of the distribution network, and the communication network of the microgrid, construct an event-triggered leader-follower distributed controller, and the output of the virtual impedance expression is input as a state variable; Step 4, determine the trigger condition of the leader-follower distributed controller. When the trigger condition is met, the leader-follower distributed control is triggered to generate a virtual impedance, and at the same time, each inverter is controlled for distributed cooperative control based on harmonic power sharing control.

[0025] In the design of this solution, an event-triggered leader-follower microgrid harmonic sharing control strategy is adopted, taking into account both harmonic sharing and the governance of the bus voltage, and an event-triggered mechanism is adopted to effectively reduce the communication burden between inverters; at the same time, unnecessary data transmission is avoided, and the power quality of the microgrid is maximally improved. By setting the value of the virtual leader node, the magnitude of the harmonic power absorbed by the inverter can be controlled, thereby improving the power quality, which is suitable for the requirements of the actual microgrid.

[0026] In the above-mentioned step 1, using droop control to generate a sinusoidal voltage is specifically as follows: Detect the actual output active power and reactive power of the inverter as the input signals of droop control; Multiply the deviations of the actual output active power and reactive power from the rated power by the corresponding droop coefficients respectively to obtain the frequency deviation and the voltage amplitude deviation; Superimpose the frequency deviation and the voltage amplitude deviation on the rated values respectively to obtain the actual frequency and voltage amplitude; Generate a sinusoidal voltage signal according to the actual frequency and voltage amplitude.

[0027] Specifically, since it is inconvenient to directly control the phase angle of the inverter output voltage, frequency adjustment is often used instead in practical applications. Droop control is a power feedback regulation mechanism constructed using the above characteristics. When the active power output by the inverter increases, it decreases the output voltage frequency, and when the reactive power output increases, it decreases the voltage amplitude to achieve automatic distribution of load power among distributed power sources in the microgrid. The traditional active-frequency droop and reactive-voltage droop control equations are shown as follows.

[0028] (1.1) In the above formula, f n and U n are the rated frequency and amplitude of the inverter output voltage u o respectively, and f i and U i are the actual frequency and amplitude of the output voltage u o respectively. P n and Q n are the rated active and reactive powers of the distributed power source inverter, P i and Q i are the actual output active and reactive powers, and m i and n i are the active and reactive droop coefficients respectively. Based on Equation (1.1), the complete process of the droop control link is as shown in Figure 2 shown.

[0029] The virtual impedance control principle of the inverter is as shown in Figure 3 shown. In the figure, G V (s) is the transfer function of the voltage loop, and its expression is: (1.2) In the formula, k U is the voltage loop proportional coefficient, k r1 is the resonance coefficient, ω1 and ω c are the resonance frequency and cut-off frequency of the quasi-PR controller, s is the Laplace operator, a complex variable used in frequency domain analysis.

[0030] G I (s) includes the proportional coefficient k I of the inductor current loop, the equivalent gain k pwm of the inverter, and the transfer function of the delay link. The expression of G I (s) is as follows: (1.3) In the formula, k Iis the current loop proportional coefficient, k pwm is the inverter equivalent gain, T s To control the frequency, Combining the above formula, we can get the expression of the inverter output voltage: (1.4) Where u o (s) is the Laplace transform of the inverter output voltage, G(s) is the system open-loop transfer function, u ref (s) is the Laplace transform of the reference voltage, Z eq (s) is the equivalent impedance, including the inherent characteristics of the inverter and the virtual impedance, i o (s) is the Laplace transform of the inverter output current, L f is the filter inductor, C f is the filter capacitor, R f is the filter resistor, Z o (s) is the inherent output impedance of the inverter, Z v (s) is the virtual impedance, G vir (s) is the transfer function related to the virtual impedance.

[0031] In the step 2, the method for extracting the harmonic current of the distribution network is to separate and extract the harmonic currents of different orders by using a method based on the cross-cancellation feedback of a second-order generalized integral orthogonal signal generator.

[0032] Specifically, such as Figure 4 As shown, the transfer function expression of the SOGI-QSG module is as follows: (1.5) Where, ω h is the resonant frequency, k h Used to determine the bandwidth of SOGI-QSG. hα (s) is the coupling coefficient of the hth harmonic on the α axis, G hβ (s) is the coupling coefficient of the hth harmonic on the β axis, G hα (s) and G hβ (s) in ω h The amplitude gain at is 1, but the phases are 0° and 90°, respectively. After cross-cancellation feedback, the transfer function of current separation extraction at different frequencies can be calculated using the following equation.

[0033] (1.6) (1.7) In the above formula, T nα (s) is the transfer function of the hth harmonic on the α axis, T hβ(s) is the transfer function of the h - th harmonic on the β - axis, T nα (s) and T hβ (s) also have an amplitude gain of 1 at ω h and a phase difference of 90°. is the sum of the transfer functions of other harmonics except the h - th harmonic on the α - axis.

[0034] In the step 2 described above, the process of constructing the virtual impedance expression is as follows: After separating and extracting different - order harmonic currents, by multiplying the harmonic current by an impedance coefficient, the harmonic voltage reference signal of the distributed - power inverter output is obtained, and then the virtual impedance of the distributed - power inverter at the harmonic frequency is obtained. Specifically, as shown in Equation as follows: (1.8) where, R vh and L vh are the values of the virtual harmonic resistance and inductance to be designed respectively.

[0035] The step 3 described above is specifically as follows: Construct the state - space model of the system harmonic power, regard each inverter as an agent, and define the error between the agent and the virtual leader node. When there is a spanning tree in the communication network, the agent state can converge to the leader node; Introduce an event - triggered mechanism, set the time - varying error of each agent, and update the control input of the agent when the trigger condition is met to avoid continuous communication; Design the control protocol, integrate the latest trigger states of itself and its neighbors, and perform collaborative updates.

[0036] In the process of designing the control protocol, integrating the latest trigger states of itself and its neighbors, and performing collaborative updates, a consensus variable is also introduced. The harmonic power and the remaining capacity are integrated into a single variable. When the remaining capacity of the inverter decreases, the consensus variable automatically increases, triggering the control system to reduce the harmonic absorption amount to prevent overload.

[0037] Specifically, the state - space model of the system harmonic power can be constructed as: (1.9) u i is the control input of each agent. The error between each agent and the leader node is defined as (1.10) In the formula, w i (t) is a quantity that changes with time t, x i (t) represents the state variable of the i - th object at time t, and x0 is a reference benchmark value.

[0038] When there is a spanning tree, the decision values of each agent will converge to the value of the leader node.

[0039] In leader-follower distributed control, each agent follows the information from adjacent agents to determine its own event-triggering time, and then updates its control input. For each agent i, a time-varying error is introduced and . The sequence of event-triggered executions is t 0i , t 1i …, corresponding to a control sequence u(t0), u(t1). Between control updates, the value of u is held constant in a zero-order hold manner and is equal to the previous control update, i.e., (1.11) where u(t) is a function of time t, and u(t i ) is the value of the function u(t) at time t i .

[0040] According to this method, the time-varying error is defined by the following formula: (1.12) where α i (t) represents the difference between the state variable x i (t) and the value of x at the start of this interval i , β i (t) represents the difference between the state variable w i (t) and the value of w at the start of this interval i , represents the time of the k-th trigger of the i-th agent, The control protocol of this paper is as follows: (1.13) where , , . Therefore, for each , is the time of the last event trigger of agent j. For each agent j, the time of its last event trigger is recorded. Therefore, each agent incorporates the latest trigger status value of each neighbor node into its control law. And the control strategy of agent i has a dual update mechanism: one is based on its own event trigger time, and the other is to synchronously trigger the event response time of adjacent nodes, so as to achieve the collaborative update of local control parameters.

[0041] To avoid the situation of a sharp increase in variables, the remaining capacity is directly reflected in the consensus variable of the controller. The present invention designs a new consensus variable as shown in the following formula: (1.14) In the formula, represents the quantity related to harmonics of the i-th object at time t, represents the remaining quantity of the i-th object at time t, represents the ratio of the two, quantifying the proportion of the harmonics-related quantity of the i-th object at time t in the total related quantity (harmonics + remaining).

[0042] At the same time, the value of the virtual leader node is also consistent with the formula of . By setting different values, we can make the inverter absorb more harmonic power. The virtual leader node adopted by the present invention is a numerical value and does not need to be transmitted through an actual line.

[0043] The additional virtual impedance can be expressed as: (1.15) In the formula, represents the virtual inductance value of the h-th harmonic, represents the virtual resistance value of the h-th harmonic, and represent the gain coefficients of the inductance and resistance.

[0044] In step 3 described above, the Lyapunov method is also used to prove the stability of the leader-follower distributed controller control strategy.

[0045] In step 4 described above, the triggering condition of the leader-follower distributed controller is determined by the stability analysis result and the execution condition. When the stability value reaches the triggering threshold, the controller performs sampling and output, and then updates the value stored in the controller triggered by the previous event.

[0046] The microgrid power quality optimization control device based on the event-triggered mechanism includes: A voltage generation and solution module, which is used to generate a sinusoidal voltage by droop control and solve the bus voltage using virtual impedance control; A harmonic current processing module, which is used to extract the harmonic current of the distribution network and construct a virtual impedance expression; A controller construction module, which is used to construct an event-triggered leader-follower distributed controller according to the extracted harmonic current of the distribution network and the communication network of the microgrid; The triggering and control module is used to determine the triggering conditions of the leader-follower distributed controller. When the triggering conditions are met, the leader-follower distributed control is triggered to generate virtual impedance, and at the same time, each inverter is controlled for distributed cooperative control based on harmonic power sharing.

[0047] The described triggering and control module includes: The stability analysis unit is used to prove the stability of the control strategy using the Lyapunov method and determine the relationship between the triggering threshold and system parameters; The threshold dynamic adjustment unit is used to adjust the triggering threshold in real time according to the frequency fluctuation and voltage deviation of the microgrid to balance the control accuracy and communication overhead.

[0048] To verify the effectiveness of the proposed adaptive virtual impedance control strategy in the microgrid system, a multi-bus distribution network simulation model is built in Matlab / Simulink, as Figure 5 shown.

[0049] The simulation parameters are shown in Table 1: Table 1 Simulation parameters of each component of the microgrid ; Figure 6 What is shown is the ratio of the harmonic power of each inverter to the remaining capacity. When the control is applied at 2 s, it can be observed that the remaining capacity and harmonic power of the three inverters finally reach the set leader values, which well avoids the overload of the inverters.

[0050] Figure 7 What is shown represents the triggering sequence of the inverter after the control is applied. When the median value is 1, it means that the event trigger controller reaches the threshold at this time, meets the triggering conditions, and data acquisition and transmission are carried out, and then virtual impedance is applied. When its value is 0, it means that there is no trigger at this time, and the controller does not perform data transmission. Table 2 shows the triggering ratio of each inverter under this control method compared with the traditional control. It can be observed that, compared with the traditional method, this control method can save about 99% of data transmission, indicating that this control method can greatly reduce the communication burden and well avoid invalid data transmission.

[0051] Table 2 Triggering time ratio of each inverter ; From Figure 8 it can be seen that before the control is applied, the bus voltage distortion rate is about 7.8%, and after the control is applied, the voltage distortion rate is about 4.3%. The power quality of this microgrid is greatly improved, indicating that this method can be effectively applied to the actual microgrid and can effectively improve the power quality of the microgrid on the premise of preventing inverter overload.

[0052] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the embodiments disclosed herein. The present application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include well-known common general knowledge or conventional technical means in the technical field not disclosed in the present application.

[0053] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present application is only limited by the appended claims.

Claims

1. A method for optimizing the power quality control of a microgrid based on an event-triggered mechanism, characterized in that It includes the following steps: Step 1: Generate a sinusoidal voltage using droop control and solve for the bus voltage using virtual impedance control; Step 2: Extract the harmonic current of the distribution network and construct a virtual impedance expression based on the relationship between the bus voltage and the harmonic current; Step 3: Construct an event-triggered leader-follower distributed controller based on the fundamental component of the sinusoidal voltage, the extracted harmonic current of the distribution network, and the communication network of the microgrid, with the output of the virtual impedance expression input as a state variable; Step 4: Determine the trigger condition of the leader-follower distributed controller. When the trigger condition is met, the leader-follower distributed control is triggered to generate a virtual impedance, and at the same time, each inverter is controlled for distributed collaborative control based on harmonic power sharing.

2. The microgrid power quality optimization control method based on an event-triggered mechanism according to claim 1, characterized in that In the said Step 1, generating a sinusoidal voltage using droop control is specifically as follows: Detect the actual output active power and reactive power of the inverter as the input signals of droop control; Multiply the deviations of the actual output active power and reactive power from the rated power by the corresponding droop coefficients respectively to obtain the frequency deviation and the voltage amplitude deviation; Superimpose the frequency deviation and the voltage amplitude deviation on the rated values respectively to obtain the actual frequency and the voltage amplitude; Generate a sinusoidal voltage signal based on the actual frequency and the voltage amplitude.

3. The microgrid power quality optimization control method based on an event-triggered mechanism according to claim 1, characterized in that In the said Step 2, the method for extracting the harmonic current of the distribution network is to realize the separation and extraction of different-order harmonic currents by using the method of cross cancellation feedback based on a second-order generalized integral orthogonal signal generator.

4. The microgrid power quality optimization control method based on an event-triggered mechanism according to claim 3, characterized in that, In the said Step 2, the process of constructing the virtual impedance expression is as follows: After completing the separation and extraction of different-order harmonic currents, multiply the harmonic current by an impedance coefficient to obtain the reference signal of the harmonic voltage output by the distributed power inverter, and then obtain the virtual impedance of the distributed power inverter at the harmonic frequency.

5. The microgrid power quality optimization control method based on an event-triggered mechanism according to claim 1, characterized in that The said Step 3 is specifically as follows: Construct a state-space model of the system harmonic power, regard each inverter as an agent, and define the error between the agent and the virtual leader node. When there is a spanning tree in the communication network, the agent state can converge to the leader node; Introduce an event-triggered mechanism, set the time-varying error of each agent, and update the control input of the agent when the trigger condition is met to avoid continuous communication; Design a control protocol to integrate the latest trigger states of itself and its neighbors for collaborative update.

6. The microgrid power quality optimization control method based on an event-triggered mechanism according to claim 5, characterized in that In the process of the said design of the control protocol to integrate the latest trigger states of itself and its neighbors for collaborative update, a consensus variable is also introduced, and the harmonic power and the remaining capacity are integrated into a single variable. When the remaining capacity of the inverter decreases, the consensus variable automatically increases, triggering the control system to reduce the harmonic absorption amount to prevent overload.

7. The microgrid power quality optimization control method based on an event-triggered mechanism according to claim 5, characterized in that In the said Step 3, the Lyapunov method is also used to prove the stability of the control strategy of the leader-follower distributed controller.

8. The microgrid power quality optimization control method based on an event-triggered mechanism according to claim 6, characterized in that, In the said Step 4, the trigger condition of the leader-follower distributed controller is determined by the stability analysis result and the execution condition. When the stability value reaches the trigger threshold, the controller samples and outputs, and then updates the value stored in the previous event-triggered controller.

9. A microgrid power quality optimization control device based on an event-triggered mechanism, characterized in that, It includes: A voltage generation and solution module for generating a sinusoidal voltage using droop control and solving for the bus voltage using virtual impedance control; Harmonic current processing module, which is used to extract the harmonic current of the distribution network and construct a virtual impedance expression; Controller construction module, which is used to construct an event-triggered leader-follower distributed controller according to the extracted harmonic current of the distribution network and the communication network of the microgrid; Triggering and control module, which is used to determine the triggering condition of the leader-follower distributed controller. When the triggering condition is satisfied, the leader-follower distributed control is triggered to generate a virtual impedance, and at the same time, each inverter is controlled for distributed cooperative control based on harmonic power sharing.

10. The microgrid power quality optimization control device based on an event-triggered mechanism according to claim 9, characterized in that, The described triggering and control module includes: Stability analysis unit, which is used to prove the stability of the control strategy using the Lyapunov method and determine the relationship between the triggering threshold and the system parameters; Threshold dynamic adjustment unit, which is used to adjust the triggering threshold in real time according to the frequency fluctuation and voltage deviation of the microgrid to balance the control accuracy and communication overhead.

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