Direct-current micro-grid distributed event trigger control method with quantitative information

Abstract

The invention discloses a DC micro-grid distributed event trigger control method with quantitative information. Each distributed power supply obtains a current correction value, an estimated value of local average voltage and a voltage correction value through own information (output voltage and current percentage) and neighbor information (current percentage); second-level control is introduced on the basis of main control, an event triggering mechanism is combined, the lower bound of the time interval of the event triggering moment is analyzed, a uniform quantification mechanism is combined, discrete quantification processing is conducted on interactive information amount, a current correction value and a voltage correction value are updated, a distributed second-level controller is designed, and a reference voltage value used for bottom layer control is generated. The invention aims to introduce a distributed control and event trigger mechanism and a quantization mechanism to the DC micro-grid, and control target current to be proportionally distributed and voltage to be adjusted under the condition of reducing communication frequency and output transmission quantity.

Description

Technical Field

[0001] The present invention relates to the field of DC microgrid control, and particularly to a distributed event-triggered control method for a DC microgrid with quantization information. Background Art

[0002] With the large-scale access of renewable energy to the power grid, the microgrid, as a small-scale power generation and distribution system including distributed power sources, energy storage devices and loads, is a reliable way to connect distributed power sources to the distribution network. It lays the foundation for the efficient utilization of new energy and has great research significance. Among them, the islanded microgrid is usually applied in remote mountainous areas or islands and other scattered power demand occasions, or in emergency situations such as large power grid failures, and is temporarily disconnected from the external power grid to ensure the power supply reliability inside the microgrid. In order to ensure the stable operation of large-scale islanded microgrids, researchers have designed the control of the controllers included in distributed power inverters to improve the adaptability of the microgrid to the bandwidth and communication frequency of the communication environment.

[0003] Currently, in the research on distributed control methods for DC microgrids considering communication constraints, the event-triggered error of non-periodic communication and the quantization error of its output transmission signal are not considered. For example, in CN 117081030 A, only the distributed preset time optimization is considered. Summary of the Invention

[0004] Aiming at the possible communication constraints and the problem that the existing distributed secondary control strategy for DC microgrids does not consider the event-triggered error and the quantization error of its output transmission signal, the present invention provides a distributed event-triggered control method for a DC microgrid with quantization information. The purpose is to realize the local voltage recovery and current proportional distribution of the DC microgrid under the background of introducing an event-triggered mechanism and discrete quantization interaction information in the DC microgrid, further reduce the output data transmission volume and communication frequency, and improve the control performance of the system.

[0005] To solve the above technical problems, the present invention is realized by the following method:

[0006] A distributed event-triggered control method for a DC microgrid with quantization information, which introduces an event-triggered mechanism and discrete quantization interaction information in the DC microgrid to realize the local voltage recovery and current proportional distribution of the DC microgrid, further reduce the output data transmission volume and communication frequency, and improve the control performance of the system.

[0007] The control method has the following steps

[0008] S1. Each distributed power inverter forms a current correction value by obtaining the ratio of its own output current value to the maximum current load and the output current values of adjacent inverters.

[0009] S2. Design a distributed voltage observer so that each distributed power source can obtain an estimated value of the local average voltage based on its current correction value; each distributed power source inverter forms a voltage correction value according to the estimated value of its own local average voltage and the nominal voltage.

[0010] S3. Introduce secondary control on the basis of primary control, and design a distributed secondary controller based on continuous signals by using the current correction value and the voltage correction value;

[0011] S4. Establish an event-triggering mechanism, analyze the lower bound of the time interval at the event-triggering moment according to the difference between the information interaction value at the event-triggering moment and the actual measured information interaction value, so as to meet the control objectives of local voltage regulation and current proportional distribution; combined with the uniform quantization mechanism, discretely quantize the amount of information to be interacted, and update the current correction value and the voltage correction value to reduce the demand of the controller for communication bandwidth;

[0012] S5. Each distributed power source, according to its own current correction value and voltage correction value, jointly acts as a distributed secondary controller considering limited communication bandwidth to generate a reference voltage value for underlying control, and repeat S1 - S5 until the current output voltage value of each distributed power source is adjusted to the nominal voltage and the output current value is proportionally distributed according to the maximum load capacity.

[0013] The distributed power source current correction model for the islanded microgrid according to step S1 is as follows:

[0014]

[0015] where w ij is an element of the communication network adjacency matrix; I i (t) is the output current value of distributed power source i; I ci is the maximum load current value of distributed power source i; I / I c represents the amount of information for information interaction between adjacent distributed power sources; N i represents the set of power sources adjacent to distributed power source i.

[0016] The distributed voltage observer for the islanded microgrid according to step S2 is as follows:

[0017]

[0018] where is the estimated value of the average voltage of distributed power source i; V i (t) is the output voltage of distributed power source i; δ 1 , δ 2 are the feedback gains of the voltage signal and the current signal respectively.

[0019] The distributed power voltage correction model described in step S2 is as follows:

[0020]

[0021] In the formula, v n is the rated voltage of distributed power source i.

[0022] is the voltage deviation caused by the correction main control. The distributed secondary controller described in step S3 is as follows:

[0023]

[0024] In the formula, V bi represents the bus voltage reference value generated by the controller. With the help of PWM technology (pulse width modulation technology), the bus voltage can quickly and accurately track the generated voltage reference value. Therefore, the internal dynamics of the distributed power source can be ignored, and it is reasonably assumed that the two are equal, that is, V i = V bi .

[0025] Considering the limited communication bandwidth, an aperiodic communication scheme is introduced. The event trigger condition described in step S4 is as follows:

[0026]

[0027] In the formula, represents the kth moment when the distributed power source i meets the event trigger condition; e i1 represents the event trigger error, that is, the difference between the measured information interaction value and the actual information interaction value of the distributed power source i at the trigger moment; α i1 , α i2 are undetermined positive constants.

[0028] To reduce the communication transmission volume, the uniform quantization mechanism described in step S4 is as follows:

[0029]

[0030] In the formula, represents the rounding operation on the calculation content; Δ represents the quantization level. In the present invention, Δ is set so that to meet the control objective;

[0031] e i2 represents the quantization error, that is, the difference between the digital quantity and the analog quantity of the interaction information at the trigger moment, which is expressed as follows:

[0032]

[0033] Furthermore, the design of the distributed secondary controller considering the limited communication bandwidth described in step S5 is as follows:

[0034]

[0035] Wherein, respectively represent the updated current and voltage correction values after event-triggered screening and quantization processing.

[0036] The distributed secondary control device for an islanded DC microgrid includes:

[0037] A global average voltage observation module, which uses the current output voltage of each distributed power source to update the estimated value of the global average voltage.

[0038] A local average voltage observation module, for each distributed power source, based on its own current output voltage and the output voltages of its adjacent distributed power sources, uses a distributed voltage control model to update its own estimated value of the average voltage;

[0039] A distributed secondary control module, for each distributed power source, uses a distributed voltage control model to generate an average voltage correction value, and a distributed current control model to generate a current correction value, and controls the output voltage and current through a controller; continuously adjusts the global average voltage observation module and the local average voltage observation module until each distributed power source realizes proportional current distribution and voltage regulation to the nominal value.

[0040] Compared with the prior art, the present invention has at least the following beneficial effects:

[0041] Based on the multi-agent consensus theory and hierarchical control framework, the present invention considers the different line impedance effects between inverters and proposes a distributed secondary controller, which can simultaneously compensate for the voltage deviation caused by the primary control and achieve accurate proportional current distribution.

[0042] Considering the situation where the communication network is restricted, a new event-triggered communication scheme is proposed. This scheme combines the event-triggered method with the uniform quantization mechanism and proposes a distributed controller, which reduces the communication burden while realizing current distribution and local voltage regulation.

[0043] This controller only outputs the quantized interaction current information at discrete moments, ensuring the proportional sharing of current and voltage regulation in terms of both communication frequency and transmission data volume. Compared with the traditional controller, the present invention saves communication resources and has certain engineering application value. Description of the Drawings

[0044] Figure 1 is the flowchart of the method of the present invention;

[0045] Figure 2 is the physical topology of the multi-bus islanded DC microgrid in the embodiment of the present invention;

[0046] Figure 3 Communication topology between distributed power sources in the multi-bus island DC microgrid of the embodiment;

[0047] Figure 4 Schematic diagram of droop control;

[0048] Figure 5 Output voltage and output current values of each distributed power source are obtained by adopting distributed secondary control in the embodiment;

[0049] Figure 6 Output voltage and output current values of each distributed power source are obtained by adopting the distributed event-triggered control with quantization information designed by the present invention in the embodiment;

[0050] Figure 7 Global voltage average value is obtained by adopting the distributed event-triggered control with quantization information designed by the present invention in the embodiment;

[0051] Figure 8 Event-triggered time series diagram is obtained by adopting the distributed event-triggered control with quantization information designed by the present invention in the embodiment;

[0052] Figure 9 Discrete quantization diagram is obtained by adopting the distributed event-triggered control with quantization information designed by the present invention in the embodiment;

[0053] Figure 10 Communication times comparison diagram is obtained by adopting the distributed event-triggered control with quantization information designed by the present invention in the embodiment. Specific implementation manner

[0054] To make the technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be described in detail and completely below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0055] As a specific implementation manner of the present invention, in combination with Figures 1 to 4 shown in the figure, a distributed event-triggered control method for a DC microgrid with quantization information is as follows:

[0056] S1. Each distributed power source inverter forms a current correction value by obtaining the ratio of its own output current value to the maximum current load and that of adjacent inverters.

[0057] Among them, the current correction model of the distributed power source in the multi-bus island microgrid is:

[0058]

[0059] where w ij is an element of the communication network adjacency matrix; I i (t) is the output current value of distributed power source i; I ci is the maximum load current value of distributed power source i; I / I c represents the amount of information exchanged between adjacent distributed power sources, which is the percentage of the output current in the maximum load; N i represents the set of power sources adjacent to distributed power source i.

[0060] It should be noted that, as Figure 2 shown in the physical topology structure of the embodiment, where I i represents the output current of distributed power source i; I Li represents the current from the bus to the load. Based on Kirchhoff's current law, we can obtain:

[0061]

[0062] where G ij represents the conductance value between buses i and j.

[0063] Based on the knowledge of graph theory, the physical topology structure of the islanded DC microgrid can be expressed as G e = {V e , ε e , A e}, which is a combination of a set of nodes through a series of edges and connection weights. Each node V e in graph G e represents a distributed power source, and the edge ε e in graph G e represents the communication link for data exchange between distributed power sources, and A e represents the weight characteristic of the communication link. Denote the set of nodes connected to node i. According to whether there is a link (i, j) ∈ ε e allowing information interaction between node i and node j, the connection relationship of each point in the graph can be reflected by the adjacency matrix of the graph. The node admittance matrix is given by the following formula:

[0064]

[0065] The current correction model in step S1 can be further expressed as:

[0066]

[0067] S2. Design a distributed observer so that each distributed power source can obtain an estimated value of the local average voltage based on its current correction value; each distributed power source inverter forms a voltage correction value according to the estimated value of its own local average voltage and the nominal voltage.

[0068] The distributed power source voltage correction model for the islanded microgrid according to step S2 is as follows:

[0069]

[0070] In the formula, v n is the nominal voltage of distributed power source i; is the estimated value of the average voltage of distributed power source i; V i (t) is the output voltage of distributed power source i; δ 1 , δ 2 are the feedback gains of the voltage signal and the current signal respectively.

[0071] It should be noted that each distributed power source is equipped with its corresponding inverter, and information interaction between distributed power sources is completed through a dedicated communication network, and this communication network can be described by graph theory knowledge. The information flow of the communication network is represented by the directed graph G c ={V c , ε c , W c}, where each node V c in the graph G c represents the corresponding distributed power source, and the edge ε c between any two nodes represents the communication link between the corresponding two distributed power sources, and W c is the adjacency matrix of the graph G c , and its element w ij represents the communication weight between node i and node j, represents the set of nodes connected to node i.

[0072] Among them, the adjacency matrix W c is expressed as follows:

[0073]

[0074] When the user-defined w ij = w ji , the graph G c can be defined as an undirected graph.

[0075] Define the degree matrix D c of the graph G c = diag(d 1 , d 2 , …, d n ), where the elements on the diagonal are d1 Denoting the sum of the weights occupied by node \(i\), the Laplacian matrix of graph \(G\) can be obtained as follows: c

[0076]

[0077] Since \(w\) ij \(_{ij}\) = \(w\) ji \(_{ji}\), the matrix is a positive symmetric matrix.

[0078] As shown in the communication topology structure of the embodiment Figure 3

[0079] Before designing the distributed secondary controller using local voltage information, first obtain the average voltage correction value using global voltage information as follows:

[0080]

[0081] where \(V\) i \(_i(t)\) is the output voltage of distributed power source \(i\); \(v\) n \(_i\) is the nominal voltage value of distributed power source \(i\);

[0082] S3. On the basis of primary control, introduce secondary control, and design a distributed secondary controller based on continuous signals using the current correction value and voltage correction value;

[0083] It should be noted that one of the main control objectives of a distributed DC microgrid is to achieve the distribution of output current. Let \(I\) ci \(_{max}^i>0\) represent the maximum output current of DG \(i\) (distributed power source). Inverters \(i\) and \(j\) will distribute their output currents proportionally, which can be described as:

[0084] \(I\) i \(_i\) / \(I\) ci \(_j\) = \(I\) j \(_j\) / \(I\) cj

[0085] The essence of the traditional primary control method is to adjust the output current and power distribution by controlling the equivalent output impedance of each inverter itself. Its control principle is as shown in Figure 4 , and the commonly used droop control expression in primary control is as follows:

[0086] \(V\) i \(_i\) = \(V\) i ref - \(R\) vi \(_i\)\(I\) i

[0087] where \(V\) i ref is the nominal voltage value; \(R\) vi \(_i\) is based on \(I\)​​ci Designed virtual impedance; V i is the reference voltage. It can be seen from the above formula that the existence of the virtual voltage will cause the bus voltage to drop. At this time, the current distribution relationship is:

[0088]

[0089] When the line impedance is ignored, if the bus voltages of each node are the same, the product of the output current of each energy storage and the droop coefficient remains consistent, indicating that the output power of each energy storage can be automatically distributed according to the inverse ratio of the droop coefficient.

[0090] When considering the line impedance, due to the differences in the distribution lines, the bus voltages of each node cannot be guaranteed to be exactly the same, resulting in the output currents of each load not being able to be strictly distributed according to the inverse ratio of the droop coefficient.

[0091] Droop control itself is a control with error. The bus voltage of the system is always lower than the rated value. Therefore, to solve the above problems, a hierarchical control strategy is adopted. The primary control is used to maintain the basic supply-demand balance of the system and stabilize the bus voltage; the secondary control adopts distributed control to correct the voltage deviation value of the primary control and improve the control accuracy of the system.

[0092] With the help of PWM technology (pulse width modulation technology), the bus voltage can quickly and accurately track and control the generated reference voltage. Therefore, it can be reasonably assumed that the two are equal.

[0093] Assume that the controller of each inverter can measure its output voltage and output current, and the values of these output voltage and output current can be transmitted to all adjacent inverters through the communication network. Design a distributed controller based on continuous signals as follows:

[0094]

[0095] S4. Establish an event-triggering mechanism. According to the difference between the information interaction value at the event-triggering moment and the actual measured information interaction value, analyze the lower bound of the time interval at the event-triggering moment to meet the control objectives of local voltage regulation and current proportional distribution; combine the uniform quantization mechanism to perform discrete quantization processing on the amount of information interacted, and update the current correction value and voltage correction value;

[0096] It should be noted that in actual engineering, there is usually a situation of limited communication bandwidth, which makes it difficult to achieve completely continuous monitoring and communication. Moreover, the communication network is vulnerable to various physical constraints, which in turn affects the control performance of the microgrid system. Therefore, it is necessary to consider energy and bandwidth limitations and reduce the communication frequency and output transmission volume on the premise of meeting normal communication requirements.

[0097] Generally, a periodic sampling mechanism is adopted, that is, each inverter collects converter information at fixed time intervals, and synchronously sends the sampled real-time information to its adjacent inverters. When the set periodic time interval is small enough, it can be approximately considered that the communication is continuous.

[0098] Since the system does not require frequent information exchange during steady-state operation, many sampling information in the periodic sampling scheme is redundant. To reduce the communication volume and computational load of the control system, an event-triggered communication mechanism is proposed. This non-periodic communication mechanism can effectively reduce the demand of the controller for communication bandwidth.

[0099] Specifically, each DG (distributed power source) only executes a new control action at its own event-triggering moment by sampling the latest information from local and its adjacent DGs. At the same time, the latest information of this DG will be broadcast to its adjacent DGs. In the whole process, each DG first updates the latest information of itself or its neighbors stored locally, and then reads these updated information from the local memory at the triggering moment to update the local controller.

[0100] The event-triggering condition described in step S4 is:

[0101]

[0102] In the formula, represents the k-th moment when the distributed power source i satisfies the event-triggering condition; the event-triggering error represents the information interaction value at the triggering moment and the actual measured information interaction value The difference between them; α i1 and α i2 are undetermined positive constants.

[0103] The information interaction value that satisfies the triggering condition is Then the current correction value is updated to:

[0104]

[0105] The uniform quantization condition described in step S4 is:

[0106]

[0107] In the formula, represents the rounding operation on the calculation content; Δ represents the quantization level, and in the present invention, Δ is set so that To meet the control objective;

[0108] e i2 represents the quantization error, that is, the difference between the digital quantity and the analog quantity of the interaction information at the triggering moment, which is expressed as follows:

[0109]

[0110] Then the voltage correction value is updated to:

[0111]

[0112] S5. Each distributed power source, based on its own current correction value and voltage correction value, jointly acts as a distributed secondary controller capable of achieving current distribution and voltage regulation, generates a reference voltage value for underlying control, and repeats S1 - S5 until the current output voltage value of each distributed power source is adjusted to the nominal voltage and the output current values are proportionally distributed according to the maximum load capacity.

[0113] Furthermore, the distributed secondary controller considering limited communication bandwidth is designed as:

[0114]

[0115] According to Lyapunov theory and LaSalle's invariant set theorem, it can be known that after adding the designed distributed event-triggered controller, the system will converge to the invariant set It is specifically expressed as follows

[0116]

[0117] That is, the controller can enable the system to achieve the control objectives of current sharing and voltage regulation.

[0118] It should be noted that the discrete-time information interaction value after satisfying the trigger condition and undergoing quantization processing and the continuous-time information interaction value have the following quantitative relationship:

[0119]

[0120] Correspondingly, the relationship between the updated current correction value and the original current correction value is as follows:

[0121]

[0122] Writing the involved operation formulas in augmented form, the current correction value before update is:

[0123]

[0124] The global voltage correction value is:

[0125]

[0126] The voltage correction value before update is:

[0127]

[0128] The updated current correction value is:

[0129]

[0130] The updated voltage correction value is:

[0131]

[0132] The relationship between the current correction values before and after the update is:

[0133]

[0134] Combining the event-triggering mechanism and the uniform quantization mechanism, the designed distributed event-triggering controller with quantization information is as follows:

[0135]

[0136] According to the physical topology of the system, the current-voltage relationship can be obtained as follows:

[0137]

[0138] According to the Lyapunov theory and the LaSalle invariant set theorem, the scalar function is set as follows:

[0139]

[0140] where

[0141] At this time, by proving the scalar function it can be proved that the system is asymptotically stable at the equilibrium point when t→0.

[0142] During the proof process, δ 1 and δ 2 take the following values:

[0143]

[0144] where λ Qmin represents the smallest positive eigenvalue of Q; represents the largest eigenvalue of.

[0145] Embodiment

[0146] Combined with Figure 2 the given physical topology structure diagram and Figure 3 the given communication topology structure diagram, the microgrid simulation design model of the embodiment can be determined. Here, the admittance matrix of the physical network nodes and the Laplacian matrix of the communication network are as follows:

[0147]

[0148] The initial bus voltages are all 48V; the maximum current-carrying capacities of distributed power sources 1 to 4 are 5A, 5A, 10A, and 10A respectively; δ 1 value is taken as 20, δ 2 value is taken as 0.5; when discretizing continuous signals, the simulation step size is selected as 0.01s. Figure 5 It means that at 0.5s, a designed distributed secondary controller based on continuous signals is added to the system. Through simulation, it shows that the present invention has good control effects and can achieve proportional current distribution and voltage regulation. Figure 6 It means that at 0.5s, a designed distributed event-triggered secondary controller based on quantized discrete signals is added to the system, which has good control effects and can achieve the control objectives; and combined with Figure 7 it can be known that the global average voltage of the embodiment can be stabilized at the nominal value. Figure 8 、 9 、10 Comparing the present invention with traditional controllers, among which Figure 8 is the event-trigger time sequence diagram. It can be seen that the communication frequency of the embodiment decreases and no Zeno behavior occurs; Figure 9 is the discrete quantization diagram. It can be seen that the output transmission amount of the embodiment decreases, which is beneficial for the system to adapt to the actual situation of limited communication bandwidth; Figure 10 is the communication times comparison diagram, which is the comparison of the communication times between the controller designed by the present invention and the original continuous signal controller. This intuitively shows that the controller designed by the present invention greatly reduces the event trigger times and can better adapt to the situation of limited communication bandwidth.

Claims

1. A distributed event-triggered control method for DC microgrids with quantified information, Features: In the context of introducing event triggering mechanism and discrete quantized interactive information in DC microgrid, the local voltage recovery and current proportional distribution of DC microgrid further reduce the output data transmission volume and communication frequency, and improve the control performance of the system.

2. A distributed event triggering control method for a DC microgrid with quantified information according to claim 1, It is characterized in that The following steps are involved: S1. Each distributed power inverter forms a current correction value by obtaining the ratio of its own and adjacent inverters' output current value to the maximum current load; S2. Design a distributed voltage observer so that each distributed power source can obtain an estimated value of the local average voltage according to its current correction value; each distributed power source inverter forms a voltage correction value according to its own estimated value of the local average voltage and the nominal voltage; S3. Introduce secondary control based on the main control, and use the current correction value and voltage correction value to design a distributed secondary controller based on continuous signals; S4. Establish an event trigger mechanism, and analyze the lower bound of the time interval of the event triggering time according to the difference between the information interaction value at the event triggering time and the actual measured information interaction value, so as to meet the control purpose of local voltage regulation and current proportional distribution; Combined with the uniform quantization mechanism, the interactive information is discretely quantized to update the current correction value and voltage correction value to reduce the controller's demand for communication bandwidth; S5. Each distributed power source, based on its own current correction value and voltage correction value, works together as a distributed secondary controller that takes into account the limited communication bandwidth to generate a reference voltage value for bottom-level control. S1 to S5 are repeated until the current output voltage value of each distributed power source is adjusted to the nominal voltage, and the output current value is distributed in proportion to the maximum load capacity.

3. A DC microgrid distributed event triggering control method with quantified information according to claim 2, Features: In step S1, the current correction model is: Among them, w ij is the communication network adjacency matrix element; I i (t) is the output current value of distributed power source i; I ci is the maximum load current value of distributed power source i; I / I c Represents the amount of information exchanged between adjacent distributed power sources; N i Represents the set of power sources adjacent to distributed generation i.

4. A DC microgrid distributed event triggering control method with quantified information according to claim 2, Features: In step S2, the local average voltage estimation model is: in, is the estimated average voltage of distributed power source i; V i (t) is the output voltage of distributed power source i; δ 1 , δ 2 are the feedback gains of voltage signal and current signal respectively.

5. A DC microgrid distributed event triggering control method with quantified information according to claim 4, Features: The distributed power supply voltage correction model is: Among them, v n is the nominal voltage value of distributed generation i.

6. A DC microgrid distributed event triggering control method with quantified information according to claim 2, Features: In step S3, a distributed two-level controller based on continuous signals is designed, and its expression is: Among them, V bi Indicates the bus voltage reference value generated by the controller.

7. The distributed event-triggered two-level control method of a DC microgrid with quantified information according to claim 2, Features: In step S4, an event trigger mechanism and a quantization mechanism are designed, and the current correction value and the voltage correction value are updated, wherein the event trigger mechanism is as follows: Among them, represents the kth moment when the distributed generation i meets the event triggering condition; event triggering error Indicates the information interaction value at the triggering moment Interaction value with actual measurement information The difference; α i1 , α i2 is a positive number to be determined, and the information interaction value that meets the trigger condition is Then the current correction value is updated as: The uniform quantization condition is: in, Indicates that the calculation content is rounded; Δ indicates the quantization level. The present invention sets Δ so that To meet control objectives; i2 It represents the quantization error, that is, the difference between the digital and analog quantities of the interactive information at the triggering moment, and is expressed as follows: The voltage correction value is updated to:

8. The distributed event-triggered two-level control method of a DC microgrid with quantified information according to claim 2, Features: The distributed secondary controller considering the limited communication bandwidth described in step S5 is designed as follows: in, They respectively represent the updated current and voltage correction values ​​after event trigger screening and quantization processing.

Images