A pulse sampling-based attack-aware DC microgrid distributed secondary control method

Abstract

The application discloses a kind of attack perception type direct current microgrid distributed secondary control method based on pulse sampling, the method faces single busbar direct current microgrid system with directed sparse communication network, steps are as follows: the power flow relationship of direct current microgrid system, the reference voltage relationship of primary droop control and the current dynamic relationship of converter are established;Modeling is carried out to DoS attack;At non-pulse time, auxiliary variable is continuously updated using direct current bus voltage error, at discrete pulse time, auxiliary variable is modified based on the normalized difference between local output current and neighbor distributed power output current, and secondary control signal is synchronously updated based on auxiliary variable, so as to significantly reduce communication and sampling cost;At the same time, a variable-period sampling strategy is designed to detect attacks based on the state of the communication link, thereby enhancing system resilience without relying on continuous monitoring or data reconstruction.

Description

Technical Field

[0001] This invention relates to the field of DC microgrid control technology, and in particular to a distributed secondary control method for attack-aware DC microgrids based on pulse sampling. Background Technology

[0002] With the growing prominence of the global energy crisis and environmental issues, DC microgrids have received widespread attention. To ensure the reliable operation of DC microgrids, control strategy design is crucial. Voltage regulation and current distribution are typically considered the primary control objectives of DC microgrids. To achieve these objectives, DC microgrids often employ a hierarchical control structure, typically including a primary control layer and a secondary control layer. The primary control layer often utilizes droop control to achieve proportional current distribution among distributed power sources; however, droop control can cause a deviation in the DC bus voltage relative to the rated reference value, thus requiring a secondary control layer to compensate for this voltage deviation.

[0003] Existing secondary control methods can be divided into centralized and distributed approaches. Centralized schemes generate control commands based on globally collected information and send them to local controllers, which facilitates system operation and maintenance. However, they are highly dependent on the central controller, and a failure of the central controller can lead to performance degradation or even loss of control. Distributed control adjusts control actions in real time based on local information and operating conditions, offering better flexibility, autonomy, adaptability, and scalability.

[0004] DC microgrids, which rely on communication networks, are vulnerable to cyberattacks, threatening their stability and security. Cyberattacks typically include spoofing attacks and denial-of-service (DoS) attacks. Spoofing attacks mislead the control system by injecting malicious data; DoS attacks disrupt information transmission, potentially causing system instability. Compared to spoofing attacks, DoS attacks can cause more comprehensive and rapid system performance degradation, posing a greater risk to DC microgrids. Therefore, ensuring that DC microgrids simultaneously achieve voltage regulation and current distribution while minimizing communication overhead during DoS attacks is a pressing technical challenge. Summary of the Invention

[0005] To address the above problems, this invention provides a distributed secondary control method for attack-aware DC microgrids based on pulse sampling. The proposed method can adaptively adjust the control update time in the presence of DoS attacks and update the control signal only at discrete pulse times, thereby achieving bus voltage recovery and proportional current sharing, and can significantly reduce communication costs and sampling overhead.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect provides a distributed secondary control method for attack-aware DC microgrids based on pulse sampling, comprising the following steps:

[0008] Step 1: Construct a single-bus DC microgrid system and establish the power flow relationship, primary droop control reference voltage relationship, and converter current dynamic relationship of the DC microgrid system;

[0009] Step 2: Model the DoS attack as a switching function that alternates between DoS attack intervals and DoS idle intervals;

[0010] Step 3: Design a distributed elastic pulse secondary controller based on auxiliary variables. During non-pulse times, the auxiliary variables are continuously updated using the DC bus voltage error to achieve bus voltage compensation. During discrete pulse times, the auxiliary variables are corrected based on the normalized difference between the local output current and the output current of the neighboring distributed power source, and the secondary control signal is updated synchronously through the auxiliary variables to achieve proportional current sharing. At the same time, a variable period sampling strategy for attack detection based on the communication link status is designed.

[0011] Step four, during runtime, the attack-aware variable-period sampling strategy is executed according to the communication link status. After obtaining the output current of the neighboring distributed power source, the distributed elastic pulse secondary controller calculates the secondary control signal and outputs the secondary control signal to the actuator for the actuator to apply control.

[0012] The above technical solution designs a distributed pulse secondary control framework. It updates the auxiliary signal only at discrete pulse moments using the normalized current value of neighboring distributed power sources, and synchronously updates the secondary control signal through the auxiliary signal, thereby achieving DC bus voltage recovery and proportional current distribution while reducing sampling and communication costs. Furthermore, it designs an attack-aware non-uniform pulse scheduling strategy to dynamically adjust the sampling time according to the communication status, ensuring that the pulse controller can effectively acquire information under both normal and attacked conditions. When the communication link is attacked by a DoS attack at the planned sampling time, causing data to be unreceived, the sampling period is adjusted from the nominal value... Switch to a smaller cycle The system detects when communication is restored; once the output current of the neighboring distributed power source is successfully received at an intermediate sampling time, the DoS attack is considered to have stopped, and the normal sampling rhythm is resumed.

[0013] It is important to note that the calculation and output update of the secondary control signal are performed immediately after sampling. Therefore, the timing of the control update is completely synchronized with the sampling time and adaptively adjusts as the sampling interval changes.

[0014] A second aspect of the present invention provides an attack-aware distributed secondary control device for a DC microgrid based on pulse sampling, comprising:

[0015] The microgrid construction module is configured to construct a single-bus DC microgrid system and establish the power flow relationship, primary droop control reference voltage relationship, and converter current dynamic relationship of the DC microgrid system.

[0016] The DoS attack building module is configured to model DoS attacks as a switching function that alternates between DoS attack intervals and DoS idle intervals.

[0017] The controller design module is configured to design a distributed elastic pulse secondary controller based on auxiliary variables. During non-pulse times, the auxiliary variables are continuously updated using the DC bus voltage error to achieve bus voltage compensation. During discrete pulse times, the auxiliary variables are corrected based on the normalized difference between the local output current and the output current of the neighboring distributed power source, and the secondary control signal is updated synchronously through the auxiliary variables to achieve proportional current sharing. At the same time, a variable period sampling strategy for attack detection based on the communication link status is designed.

[0018] The control module is configured to execute an attack-aware variable-period sampling strategy based on the communication link status during runtime. After obtaining the output current of the neighboring distributed power source, the distributed elastic pulse secondary controller calculates the secondary control signal and outputs the secondary control signal to the actuator for the actuator to apply control.

[0019] A third aspect of the present invention provides a computer device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus;

[0020] Memory, used to store computer programs;

[0021] When a processor executes a program stored in memory, it implements the steps of the attack-aware DC microgrid distributed secondary control method based on pulse sampling as described in the first aspect.

[0022] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the attack-aware DC microgrid distributed secondary control method based on pulse sampling as described in the first aspect.

[0023] The fifth aspect of the present invention provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the attack-aware DC microgrid distributed secondary control method based on pulse sampling described in the first aspect.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. This invention addresses a single-bus DC microgrid in a directed sparse communication network and designs a distributed pulse secondary control framework. The framework updates the auxiliary signal only at discrete pulse moments using the normalized current value of neighboring distributed power sources, and synchronously updates the secondary control signal through the auxiliary signal, thereby achieving DC bus voltage recovery and proportional current distribution, while reducing sampling and communication costs.

[0026] 2. This invention further designs an attack-aware non-uniform pulse scheduling strategy, dynamically adjusting the sampling time according to the communication status, thereby ensuring that the pulse controller can effectively acquire information under both normal and attacked conditions. When the communication link is attacked by a DoS attack at the planned sampling time, resulting in data unreceivable, the sampling period is adjusted from the nominal value. Switch to a smaller cycle The system detects when communication is restored; once the output current of the neighboring distributed power source is successfully received at an intermediate sampling time, the DoS attack is considered to have stopped, and the normal sampling rhythm is resumed. Attached Figure Description

[0027] Figure 1 This is a flowchart of the method of the present invention.

[0028] Figure 2 This is a simulation curve of the DC bus output voltage under a DoS attack, as shown in the figure.

[0029] Figure 3 The figure shows the simulation curves of the output current of the four converters under a DoS attack. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] Example 1

[0032] like Figure 1 As shown, this invention provides a distributed secondary control method for attack-aware DC microgrids based on pulse sampling, comprising the following steps:

[0033] Step 1: Construct a single-bus DC microgrid system and establish the power flow relationship, primary droop control reference voltage relationship, and converter current dynamic relationship of the DC microgrid system.

[0034] In one possible embodiment, the DC microgrid system includes N distributed power sources, M loads, a DC / DC converter, a common DC bus, and a directed communication network for information exchange between the distributed power sources.

[0035] Specifically, the information flow between distributed power sources is mediated by a directed communication graph. describe, For a set of nodes, Let be the set of edges. It is a weighted adjacency matrix; if and only if the distributed power source When able to receive information from distributed source j, there exists an edge. and ,otherwise ;

[0036] The Laplace matrix of the directed graph is , among which when From time to time ,when From time to time The neighbor set is And the communication is a directed graph It is strongly connected.

[0037] In one possible embodiment, the steady-state power flow relationship of the DC microgrid system is as follows:

[0038]

[0039] In the formula, For the first The line resistance between the converter and the common DC bus. This is the DC bus voltage. For the first A constant resistance load and The first The output voltage and output current of each converter.

[0040] Under a hierarchical control framework, the first The reference voltage for each converter is:

[0041]

[0042] In the formula, The rated DC bus voltage, The droop coefficient is... For the secondary control signal to be designed; I i (t) represents the output current of the i-th converter.

[0043] Based on trend relationships, the first The current dynamics of a converter can be described as follows:

[0044]

[0045] In the formula, , For the first Line conductance between each converter and the common DC bus; for The derivative of for The derivative of .

[0046] Step 2: Model the DoS attack as a switching function that alternates between DoS attack intervals and DoS idle intervals.

[0047] In one possible implementation, the DoS attack switching function is:

[0048]

[0049] In the formula, Indicates the first DoS attack range Indicates the DoS free interval. , , .

[0050] Step 3: Design a distributed elastic pulse secondary controller based on auxiliary variables to continuously update the auxiliary variables using the DC bus voltage error during non-pulse times, thereby achieving bus voltage compensation; during discrete pulse times, perform discrete pulse correction on the auxiliary variables based on the normalized difference between the local output current and the output current of the neighboring distributed power source, and synchronously update the secondary control signal through the auxiliary variables to achieve proportional current sharing; at the same time, design a variable period sampling strategy for attack detection based on the communication link status.

[0051] In one possible embodiment, the distributed elastic pulse secondary controller is:

[0052]

[0053] In the formula, and To control the gain parameters, the pulse sequence satisfy And there are , As an auxiliary variable, it is right-continuous at each pulse moment; express The left limit at time, for Auxiliary variables at time; and These are positive current distribution coefficients. express Time of the first Normalized current values ​​of the converters; express Time of the first Normalized current values ​​of the converters; Laplace matrix of the directed graph of information formed by distributed power sources Element.

[0054] It can be seen that the distributed elastic pulse secondary controller only updates the auxiliary signal using the normalized current value of the neighboring distributed power source at the discrete pulse moment, and updates the secondary control signal synchronously through the auxiliary signal. It uses the slow dynamic characteristics of the system and pulse control theory to ensure convergence, thereby realizing DC bus voltage recovery and proportional current distribution, while reducing sampling and communication costs.

[0055] In one possible embodiment, the variable-period sampling strategy for attack detection of the communication link state includes:

[0056] Attack detection and sampling acceleration: If at the predetermined sampling time , No. The converter failed to output from the first If the first converter receives data, it is determined that the communication link has been subjected to a DoS attack; at this time, in order to compensate for the loss of information, the first converter... The converter will change its sampling period from Dynamically switch to and within the time interval According to the sampling period Intensive sampling is performed to actively probe communication channels.

[0057] Attack recovery identification: If at some intermediate sampling time , No. The converter successfully switched from the first... If the first converter receives data, it determines that the DoS attack has stopped; at this time, the second converter... Each converter pauses further sampling attempts within the current interval and waits for the next predetermined sampling time. .

[0058] Sampling period recovery: at the predetermined sampling time If information transmission is successfully restored, the i-th converter will change its sampling period from... Restore to nominal value Otherwise, repeat the above steps until the message is successfully received.

[0059] Understandably, in this strategy, when the communication link is attacked by a DoS attack at the planned sampling time and data cannot be received, the sampling period is switched from the nominal value T to a smaller period τ to detect communication recovery; once the output current of the neighboring distributed power source is successfully received at the intermediate sampling time, the DoS attack is determined to have stopped, and the subsequent normal sampling rhythm is restored.

[0060] Step 4: During operation, the attack-aware variable-period sampling is performed based on the communication link status. After obtaining the output current of the neighboring distributed power source, the distributed elastic pulse secondary controller calculates the secondary control signal and outputs the secondary control signal to the actuator for the actuator to apply control.

[0061] Furthermore, the simulation control results of the attack-aware distributed secondary control method for DC microgrids based on pulse sampling are derived from... Figures 2-3 exhibit.

[0062] Figure 2 This is a graph showing the DC bus output voltage under a DoS attack. Figure 3 The graph shows the output current curves of four converters under a DoS attack. As can be seen from the graph, under... During this period, only primary control is activated. During this phase, the DC bus voltage drops to approximately 46.33V. And... During the period s, despite the DoS attack, the DC bus voltage could still recover to approximately 48V, and the output current of the four converters could converge to 1A, indicating that the proposed distributed resilient pulse secondary controller can achieve voltage recovery and proportional current distribution under DoS attacks. Simulation results verify the effectiveness of the proposed control strategy.

[0063] Example 2

[0064] Based on the same inventive concept, this application also provides an attack-aware DC microgrid distributed secondary control device based on pulse sampling, comprising:

[0065] The microgrid construction module is configured to construct a single-bus DC microgrid system and establish the power flow relationship, primary droop control reference voltage relationship, and converter current dynamic relationship of the DC microgrid system.

[0066] The DoS attack building module is configured to model DoS attacks as a switching function that alternates between DoS attack intervals and DoS idle intervals.

[0067] The controller design module is configured to design a distributed elastic pulse secondary controller based on auxiliary variables. During non-pulse periods, the auxiliary variables are continuously updated using the DC bus voltage error to achieve bus voltage compensation. During discrete pulse periods, the auxiliary variables are corrected based on the normalized difference between the local output current and the output current of neighboring distributed power sources. The secondary control signal is then updated synchronously through the auxiliary variables to achieve proportional current sharing. Simultaneously, a variable-period sampling strategy for attack detection based on the communication link status is designed.

[0068] The control module is configured to execute an attack-aware variable-period sampling strategy based on the communication link status during runtime. After obtaining the output current of the neighboring distributed power source, the distributed elastic pulse secondary controller calculates the secondary control signal and outputs the secondary control signal to the actuator for the actuator to apply control.

[0069] Example 3

[0070] Based on the above embodiments, this embodiment provides a controller, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the method described in Embodiment 1.

[0071] Example 4

[0072] Based on the above embodiments, this embodiment provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the method described in Embodiment 1.

[0073] Example 5

[0074] Based on the above embodiments, this embodiment provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the method described in Embodiment 1.

[0075] Finally, it should be noted that the foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A distributed secondary control method for attack-sensing DC microgrids based on pulse sampling, characterized in that, Includes the following steps: Step 1: Construct a single-bus DC microgrid system and establish the power flow relationship, primary droop control reference voltage relationship, and converter current dynamic relationship of the DC microgrid system; Step 2: Model the DoS attack as a switching function that alternates between DoS attack intervals and DoS idle intervals; Step 3: Design a distributed elastic pulse secondary controller based on auxiliary variables to continuously update the auxiliary variables using the DC bus voltage error during non-pulse times, thereby achieving bus voltage compensation; during discrete pulse times, perform discrete pulse correction on the auxiliary variables based on the normalized difference between the local output current and the output current of the neighboring distributed power source, and synchronously update the secondary control signal through the auxiliary variables to achieve proportional current sharing; at the same time, design a variable period sampling strategy for attack detection based on the communication link status. Step four, during runtime, the attack-aware variable-period sampling strategy is executed according to the communication link status. After obtaining the output current of the neighboring distributed power source, the distributed elastic pulse secondary controller calculates the secondary control signal and outputs the secondary control signal to the actuator for the actuator to apply control.

2. The distributed secondary control method for attack-aware DC microgrids based on pulse sampling according to claim 1, characterized in that, In step two, the steady-state power flow relationship of the DC microgrid system is as follows: In the formula, For the first The line resistance between the converter and the common DC bus. This is the DC bus voltage. For the first A constant resistance load and The first The output voltage and output current of each converter; Under a hierarchical control framework, the first The reference voltage for each converter is: In the formula, The rated DC bus voltage, The droop coefficient is... For the secondary control signal to be designed; I i (t) is the th The output current of the converter; Based on trend relationships, the first The current dynamics of the converter can be described as follows: In the formula, , For the first Line conductance between each converter and the common DC bus; for The derivative of for The derivative of .

3. The distributed secondary control method for attack-aware DC microgrids based on pulse sampling according to claim 2, characterized in that, In step three, the distributed elastic pulse secondary controller is: In the formula, and To control the gain parameters, the pulse sequence satisfy And there are , As an auxiliary variable, it is right-continuous at each pulse moment; express The left limit at time, for Auxiliary variables at time; and These are positive current distribution coefficients. express Time of the first Normalized current values ​​of the converters; express Time of the first Normalized current values ​​of the converters; Laplace matrix of the directed graph of information formed by distributed power sources Element.

4. The distributed secondary control method for attack-aware DC microgrids based on pulse sampling according to claim 1, characterized in that, The DoS attack switching function is: In the formula, Indicates the first DoS attack range Indicates the DoS free interval. , , .

5. The distributed secondary control method for attack-aware DC microgrids based on pulse sampling according to claim 4, characterized in that, The variable-period sampling strategy for attack detection based on communication link status includes: Attack detection and sampling acceleration: If at the predetermined sampling time , No. The converter failed to output from the first If a converter receives data, it is determined that the communication link has been subjected to a DoS attack. Therefore, within the specified time interval... within, no. The converter changes its sampling period from the nominal value Dynamically switch to Dense sampling is performed to actively probe the communication channel, whereby... ; Attack recovery identification: If at some intermediate sampling time , , No. The converter successfully switched from the first... If a transducer receives data, it determines that the DoS attack has stopped, suspends further sampling attempts within the current interval, and waits for the next scheduled sampling time. ; Sampling period recovery: at the predetermined sampling time If the information transmission is successfully restored, then the first The converter changes its sampling period from Restore to nominal value Otherwise, repeat the above steps until the information is successfully received.

6. A distributed secondary control device for an attack-aware DC microgrid based on pulse sampling, characterized in that, include: The microgrid construction module is configured to construct a single-bus DC microgrid system and establish the power flow relationship, primary droop control reference voltage relationship, and converter current dynamic relationship of the DC microgrid system. The DoS attack building module is configured to model DoS attacks as a switching function that alternates between DoS attack intervals and DoS idle intervals. The controller design module is configured to design a distributed elastic pulse secondary controller based on auxiliary variables. During non-pulse periods, the auxiliary variables are continuously updated using the DC bus voltage error to achieve bus voltage compensation. During discrete pulse periods, the auxiliary variables are corrected based on the normalized difference between the local output current and the output current of neighboring distributed power sources. The secondary control signal is then updated synchronously through the auxiliary variables to achieve proportional current sharing. Simultaneously, a variable-period sampling strategy for attack detection based on the communication link status is designed. The control module is configured to perform attack-aware variable-period sampling based on the communication link status during runtime. After obtaining the output current of the neighboring distributed power source, the distributed elastic pulse secondary controller calculates the secondary control signal and outputs the secondary control signal to the actuator for the actuator to apply control.

7. A computer device, characterized in that: It includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; When a processor executes a program stored in memory, it implements the steps of the attack-aware DC microgrid distributed secondary control method based on pulse sampling as described in any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the attack-aware DC microgrid distributed secondary control method based on pulse sampling as described in any one of claims 1 to 5.

9. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the attack-aware DC microgrid distributed secondary control method based on pulse sampling as described in any one of claims 1 to 5.

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