Data packet loss problem consistency control method and system for micro-grid fault recovery

Abstract

The invention provides a data packet loss problem consistency control method and system for micro-grid fault recovery, and the method comprises the steps: building a virtual leader-following consistency control model based on a hierarchical control architecture of a micro-grid system; calculating a deviation caused by communication packet loss to a control result of the consistency control model, selecting the deviation value as a first trigger condition, and setting a consistency control overshoot as a second trigger condition; if the steady-state error of the micro-grid system is smaller than the first trigger condition and the consistency control overshoot is smaller than the second trigger condition, completing consistency control by adopting real-time data output by droop control of each DER; otherwise, the consistency control is completed by adopting the control data output in the prediction compensation link. The dynamic change response capability of the system is effectively improved, the performance of the system is optimized, and the overall stability of the system is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of hierarchical control of microgrid distributed power sources, and in particular to a data packet loss problem consistency control method and control system for microgrid fault recovery, as well as a corresponding computer terminal and computer-readable storage medium. Background Art

[0002] In recent years, with the rapid development of the world economy and the significant improvement of people's living standards, the global demand for energy has risen sharply. This trend has put tremendous pressure on traditional energy supply methods, and there is an urgent need to seek new solutions. In this context, the introduction of distributed energy resources (DER) provides an effective way to solve the problems related to energy supply. DER can not only reduce the loss in the process of energy transmission and improve energy utilization efficiency, but also enhance the flexibility and reliability of the energy system. Therefore, it is regarded as an important supplement and effective support for future large-scale power grids. However, since distributed power sources are restricted by natural environmental conditions, such as the intermittent nature and instability of solar and wind energy, DER still has some defects in practical applications. These defects may affect the stability and reliability of the power grid. Therefore, DER needs to be effectively managed and controlled. To this end, the concept of microgrid came into being, aiming to integrate DER into the main power grid while weakening its negative impact on the power grid. At present, in microgrid systems, droop control is generally used to achieve plug-and-play of DER. However, under steady-state conditions, the system frequency and voltage often deviate from the reference value, and the ability to distribute reactive power is insufficient. This deviation not only affects the power quality, but may also lead to instability in the power system. Therefore, it is usually necessary to improve the droop control or introduce secondary control to form a hierarchical control structure to correct the frequency and voltage. In this way, the operating performance of the microgrid can be effectively improved, so that it can work better with the main grid and ensure the stability and efficiency of the power system.

[0003] At present, traditional secondary control adopts a centralized control structure based on a central controller, which requires collecting all the information of each DER and then sending control instructions to each DER. The communication network is complex and the communication volume is huge, which reduces the stability of the system. In recent years, distributed coordinated control strategies have been widely used in secondary control of microgrids. In distributed coordinated control, the controller of each DER only communicates with neighboring DERs, and no central controller is required, which improves the robustness of the system, but does not consider the communication problem of the network layer. In summary, there is still a problem of communication packet loss in microgrid control technology, and hierarchical control cannot be effectively implemented.

[0004] At present, no description or report of similar technology to the present invention has been found, and similar information at home and abroad has not been collected yet. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a data packet loss problem consistency control method and control system for microgrid fault recovery, and also provides a corresponding computer terminal and computer-readable storage medium.

[0006] According to one aspect of the present invention, a method for consistency control of data packet loss problem for microgrid fault recovery is provided, comprising:

[0007] Based on the hierarchical control architecture of the microgrid system, a virtual leader-follower consistency control model is established;

[0008] Calculate the deviation of the control result of the consistency control model caused by communication packet loss, select the deviation as the first trigger condition, and set the consistency control overshoot as the second trigger condition;

[0009] If the steady-state error of the microgrid system is less than the first trigger condition and the consistency control overshoot is less than the second trigger condition, the real-time data output by each DER through droop control is used to complete the consistency control; otherwise, the control data output in the prediction compensation link is used to complete the consistency control.

[0010] Preferably, the hierarchical control architecture based on the microgrid system is used to establish a virtual leader-follower consistency control model, including:

[0011] Providing a hierarchical control architecture for a microgrid system;

[0012] Assume that in the communication network of the hierarchical control architecture, the i-th distributed power source loses packets when transmitting information within a fixed period of time, the i-th distributed power source has N adjacent power sources for communication, the communication connection graph between the i-th distributed power source and the N adjacent power sources includes at least one directed spanning tree, and the virtual leader is set as a globally reachable point;

[0013] In the microgrid system, the voltage and frequency droop controllers of the i-th distributed generation are designed as follows:

[0014]

[0015] In the formula, ω i and U i are the output frequency and voltage of the distributed unit respectively; ω ref and U ref are the frequency reference value and the voltage reference value respectively; m i and n i is the droop coefficient, P iand Q i are the active power and reactive power of the distributed unit respectively;

[0016] According to the above droop controller design, the virtual leader-follower consistency control corresponding to the i-th distributed generation can be designed as:

[0017]

[0018] In the formula, u i is the function corresponding to the virtual leader-follower consistency controller, N i is the set of adjacent power sources of the i-th distributed power source; k xi1 and k xi2 is the undetermined gain factor; x i and x j represents the voltage or frequency of the i-th distributed power source and the j-th distributed power source; a ij is the connection relationship between the i-th distributed power source and the j-th distributed power source, b i is the connection relationship between the virtual leader and the follower. If there is a connection, then b i >0, otherwise b i =0;

[0019] The virtual leader-follower consensus protocol of the i-th distributed generation taking into account the communication packet loss problem is:

[0020]

[0021] In the formula, α i , α j and α L are the packet loss rates of the virtual leaders of distributed power sources; x L is the state quantity of the virtual leader;

[0022] Under the effect of formula (3), when k xi1 and k xi2 When certain conditions are met, the status of the follower and the virtual leader can always follow each other;

[0023] Assuming that the state equation of the microgrid system is a first-order equation, we have:

[0024]

[0025] in,

[0026]

[0027] Perform Laplace transform on equation (4):

[0028]

[0029] Where, u1 is the state quantity of the first distributed power source, u2 is the state quantity of the second distributed power source; X(s) is the state quantity after Laplace transformation; x1(t)| t＝0 and x2(t)| t＝0 are the initial values ​​of the output state quantities of the first distributed power source and the second distributed power source droop controller, respectively. The deviation between the output state quantity and the state quantity corresponding to the virtual leader is:

[0030]

[0031] At the same time, there are:

[0032]

[0033] When the gain coefficient meets the following conditions, the microgrid system can meet the consistency requirements:

[0034]

[0035] Where, c1=∫x1(t)dt| t＝0 , c2=∫x2(t)dt| t＝0 .

[0036] Preferably, the hierarchical control architecture includes: an information layer and a physical layer; wherein:

[0037] The information layer includes: a prediction compensation link calculation part, an event trigger mechanism part and a communication network part;

[0038] The physical layer includes the following interconnected parts: a primary control link, a secondary control link, a power calculation link, a voltage synthesis link, a voltage and current double closed loop link and a PWM signal generator.

[0039] Preferably, the calculating the deviation caused by communication packet loss on the control result of the consistency control model, selecting the deviation as the first trigger condition, and setting the consistency control overshoot as the second trigger condition, includes:

[0040] The deviation of the control result of the consistency control model caused by the communication packet loss refers to the degree to which the controlled quantity deviates from the expected value, wherein the controlled quantity is the frequency and voltage output by the distributed power supply droop control, and the expected value is the frequency reference value and the voltage reference value;

[0041] Taking the i-th distributed power source as the research object, the consistency protocol before and after packet loss is:

[0042]

[0043] In the formula, kxi1 and k xi2 is the gain coefficient, α i and α j is the packet loss rate of the i-th distributed power source and the k-th distributed power source, α L is the packet loss rate of the virtual leader;

[0044] After Laplace transforming equation (11), we have:

[0045]

[0046] According to Laplace's differential theorem, integral theorem and final value theorem, we can get:

[0047]

[0048] From formula (13), we can get:

[0049] x i (∞)-x i ′(∞)=Δx i (∞) (14)

[0050] In the formula, x i (∞) is the state quantity of the i-th distributed unit, x i ′ (∞) is the differential value of the i-th distributed unit, Δx i (∞) is the deviation caused by communication packet loss;

[0051] The overshoot at the initial moment of consistency control is taken as the trigger event, and the overshoot is ||∫(VLFCC)dt| t＝初始时刻 |-x L ∣, as the second trigger condition.

[0052] Preferably, the method further comprises: establishing a control trigger mechanism based on the first trigger condition and the second trigger condition; wherein:

[0053] For the i-th distributed power source, the critical values ​​of the first trigger condition and the second trigger condition are set to k respectively. ωi1 and k ωi2 , then the control trigger mechanism is established as follows: when the steady-state error is within the allowable range, that is, the error is less than k ωi1 , and the overshoot of the virtual leader-follower consistency control model is also within the corresponding allowable range, that is, the overshoot is less than k ωi2 At this time, the real-time output data of the distributed power droop control is used to complete the consistency control. Otherwise, the data obtained from the prediction compensation link is used to complete the consistency control.

[0054] Preferably, the use of control data outputted in the prediction compensation link to complete consistency control includes:

[0055] The prediction and compensation link includes an MPC model and m extreme learning machines;

[0056] Perform weighted processing on m extreme learning machines, where the i-th extreme learning machine ELM i The weight λ i for:

[0057]

[0058] In the formula, e i =y i -y ELMi ,y i For real data; is the data output by the i-th extreme learning machine;

[0059] After weighted processing, the data output by m extreme learning machines is:

[0060]

[0061] The weighted data output by the m extreme learning machines are then weighted with the data output by the MPC model predictive control to obtain:

[0062]

[0063] In the formula, λ ELM is the weighted coefficient for the extreme learning machine, y MPC is the data output by the MPC model predictive control;

[0064] After combining the output data of m extreme learning machines and the MPC model, the output prediction data is obtained for:

[0065]

[0066] The final output prediction data is used as control data for consistency control.

[0067] Preferably, it also includes: when the prediction data If the error between the predicted value and the true value is greater than the set threshold, the extreme learning machine is retrained and the weighted processing process is repeated until the output prediction data meets the error requirement.

[0068] According to another aspect of the present invention, a data packet loss problem consistency control system for microgrid fault recovery is provided, comprising:

[0069] A consistency control building module, which builds a virtual leader-follower consistency control model based on the hierarchical control architecture of the microgrid system;

[0070] A trigger condition establishment module, which is used to calculate the deviation caused by communication packet loss on the control result of the consistency control model, and select the deviation as the first trigger condition, and set the consistency control overshoot as the second trigger condition;

[0071] A hierarchical control module is used to complete consistency control using the real-time data output by droop control of each DER when the steady-state error of the microgrid system is less than the first trigger condition and the consistency control overshoot is less than the second trigger condition; otherwise, consistency control is completed using the control data output in the prediction compensation link.

[0072] According to a third aspect of the present invention, there is provided a computer terminal comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, can be used to execute any one of the methods described above in the present invention, or to run the system described above in the present invention.

[0073] According to a fourth aspect of the present invention, there is provided a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, can be used to execute any of the methods described above in the present invention, or to run the system described above in the present invention.

[0074] Due to the adoption of the above technical solution, the present invention has at least one of the following beneficial effects compared with the prior art:

[0075] The present invention is based on the idea of ​​event triggering, adopts an innovative prediction compensation mechanism, combines extreme learning machine (ELM) and model predictive control (MPC), and effectively improves the system's ability to respond to dynamic changes.

[0076] The present invention can effectively predict the future state of the system through the trigger control mechanism of virtual leader-follower consistency control, and optimize the performance of the system through a compensation control strategy.

[0077] In order to solve the common data packet loss problem in the information transmission process, the present invention proposes a virtual leader-follower consistency control strategy. By introducing the concept of virtual leader, each node of the system can still maintain consistency through the compensation control strategy when facing data loss, thereby ensuring the overall stability of the system;

[0078] The consistency control method provided by the present invention can effectively solve the communication packet loss problem faced in the hierarchical control of microgrid fault recovery, ensure the overall stability of the system, and greatly improve the control effect of the hierarchical control. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0080] Figure 1 The present invention is a flowchart of a method for controlling consistency of data packet loss for microgrid fault recovery in accordance with an embodiment of the present invention.

[0081] Figure 2 Schematic diagram of the topological structure of a consistency controller with a leader and two followers in a preferred embodiment of the present invention.

[0082] Figure 3 This is a working block diagram of the prediction compensation link combining the extreme learning machine and model predictive control in a preferred embodiment of the present invention.

[0083] Figure 4 The figure is a schematic diagram of the components of a data packet loss problem consistency control system for microgrid fault recovery in one embodiment of the present invention. DETAILED DESCRIPTION

[0084] The following is a detailed description of the embodiments of the present invention: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

[0085] In view of the problem of communication packet loss existing in the prior art, an embodiment of the present invention provides a method for consistency control of data packet loss problem for microgrid fault recovery.

[0086] Specifically, Figure 1 As shown, the data packet loss problem consistency control method for microgrid fault recovery provided by this embodiment may include the following operations:

[0087] S1, based on the hierarchical control architecture of the microgrid system, a virtual leader-follower consistency control model is established;

[0088] S2, calculating the deviation caused by communication packet loss on the control result of the consistency control model, and selecting the deviation as the first trigger condition, and setting the consistency control overshoot as the second trigger condition;

[0089] S3, if the steady-state error of the microgrid system is less than the first trigger condition and the consistency control overshoot is less than the second trigger condition, the real-time data output by the droop control of each DER is used to complete the consistency control; otherwise, the control data output in the prediction compensation link is used to complete the consistency control.

[0090] In some preferred implementations, the above S1, based on the hierarchical control architecture of the microgrid system, establishes a virtual leader-follower consistency control model; and may further include the following operations:

[0091] A hierarchical control architecture of a microgrid system is provided; in some preferred embodiments, the hierarchical control architecture may include: an information layer and a physical layer; wherein the information layer includes: a prediction compensation link calculation part, an event trigger mechanism part and a communication network part; the physical layer includes: a primary control link, a secondary control link, a power calculation link, a voltage synthesis link, a voltage and current double closed loop link and a PWM signal generator connected to each other, wherein the connection relationship between the various parts can be realized by using existing technologies and will not be repeated here; Figure 2 As shown in Figure 1, the consistency controller topology of a leader and two followers in the information layer, the followers are composed of inverters and filters, connected to the virtual leader through actual lines. The solid lines represent physical connections, and the dotted lines represent information connections.

[0092] Assume that in the communication network, the information transmitted by the i-th distributed power source within a fixed period can be considered as packet loss, the i-th distributed power source has N adjacent power sources for communication, the communication connection graph between the i-th distributed power source and the N adjacent power sources contains at least one directed spanning tree, and the virtual leader is set as a globally reachable point;

[0093] In the microgrid system, the voltage and frequency droop controller of the i-th distributed generation is:

[0094]

[0095] In the formula, ω i and U i are the output frequency and voltage of the distributed unit respectively; ω ref and U ref are the frequency reference value and the voltage reference value respectively; m i and n i is the droop coefficient, P i and Q i are the active power and reactive power of the distributed unit respectively;

[0096] According to the above design, the virtual leader-follower consistency control corresponding to the i-th distributed power source can be designed as:

[0097]

[0098] In the formula, u i is the function corresponding to the virtual leader-follower consistency controller, N i is the set of adjacent power sources of the i-th distributed power source; k xi1 and k xi2 is the undetermined gain factor; x i and x j represents the voltage or frequency of the i-th distributed power source and the j-th distributed power source; a ij is the connection relationship between the i-th distributed power source and the j-th distributed power source, b i is the connection relationship between the virtual leader and the follower. If there is a connection, then b i >0, otherwise b i =0;

[0099] The virtual leader-follower consensus protocol of the i-th distributed generation taking into account the communication packet loss problem is:

[0100]

[0101] In the formula, α i , α j and α L are the packet loss rates of the virtual leaders of distributed power sources; x L is the state quantity of the virtual leader;

[0102] Under the effect of formula (3), when k xi1 and k xi2 When certain conditions are met, the status of the follower and the virtual leader can always follow each other;

[0103] Assuming that the state equation of the microgrid system is a first-order equation, we have:

[0104]

[0105] in,

[0106]

[0107] Perform Laplace transform on equation (4):

[0108]

[0109] Where, u1 is the state quantity of the first distributed power source, u2 is the state quantity of the second distributed power source; X(s) is the state quantity after Laplace transformation; x1(t)| t＝0 and x2(t)| t＝0are the initial values ​​of the output state quantities of the first distributed power source and the second distributed power source droop controller, respectively. The deviation between the output state quantity and the state quantity corresponding to the virtual leader is:

[0110]

[0111] At the same time, there are:

[0112]

[0113] When the gain coefficient meets the following conditions, the microgrid system can meet the consistency requirements:

[0114]

[0115] Where, c1=∫x1(t)dt| t＝0 , c2=∫x2(t)dt| t＝0 .

[0116] In some preferred implementations, the above S2, calculating the deviation caused by communication packet loss on the control result of the consistency control model, and selecting the deviation as the first trigger condition, and setting the consistency control overshoot as the second trigger condition, can further include the following operations:

[0117] The deviation of the control result of the consistency control model caused by communication packet loss refers to the degree to which the controlled quantity deviates from the expected value, where the controlled quantity is the frequency and voltage output by the distributed power supply droop control, and the expected value is the frequency reference value and the voltage reference value;

[0118] Taking the i-th distributed power source as the research object, the consistency protocol before and after packet loss is:

[0119]

[0120] In the formula, k xi1 and k xi2 is the gain coefficient, α i and α j is the packet loss rate of the i-th distributed power source and the j-th distributed power source, α L is the packet loss rate of the virtual leader;

[0121] After Laplace transforming equation (11), we have:

[0122]

[0123] According to Laplace's differential theorem, integral theorem and final value theorem, we can get:

[0124]

[0125] From formula (13), we can get:

[0126] x i (∞)-x i ′(∞)=Δx i (∞) (14)

[0127] In the formula, x i (∞) is the state quantity of the i-th distributed unit, x i ′ (∞) is the differential value of the i-th distributed unit, Δx i (∞) is the deviation caused by communication packet loss;

[0128] The overshoot at the initial moment of consistency control is taken as the trigger event, and the overshoot is ||∫(VLFCC)dt| t＝初始时刻 |-x L ∣, as the second trigger condition.

[0129] In some preferred implementations, based on the above first trigger condition and the second trigger condition, the following control trigger mechanism may also be established:

[0130] For the i-th distributed power source, the critical values ​​of the first trigger condition and the second trigger condition are set to k respectively. ωi1 and k ωi2 , then the control trigger mechanism is established as follows: when the steady-state error is within the allowable range, that is, the error is less than k ωi1 , and the overshoot of the virtual leader-follower consistency control model is also within the corresponding allowable range, that is, the overshoot is less than k ωi2 At this time, the real-time output data of the distributed power droop control is used to complete the consistency control. Otherwise, the data obtained from the prediction compensation link is used to complete the consistency control.

[0131] In some preferred implementations, the above S3, using the control data output in the prediction compensation link to complete the consistency control, may further include the following operations:

[0132] Predict compensation links, such as Figure 3 As shown, it includes an MPC model and m extreme learning machines;

[0133] S31, weighting m extreme learning machines, where the i-th extreme learning machine ELM i The weight λ i for:

[0134]

[0135] In the formula, e i =y i -y ELMi ,y iFor real data; is the data output by the i-th extreme learning machine;

[0136] S32, after weighted processing, the data output by the m extreme learning machines is:

[0137]

[0138] S33, the weighted data output by the m extreme learning machines are then weighted with the data output by the MPC model predictive control to obtain:

[0139]

[0140] In the formula, λ ELM is the weighted coefficient for the extreme learning machine, y MPC is the data output by the MPC model predictive control;

[0141] S34, after combining the output data of m extreme learning machines and the MPC model, the output prediction data is obtained for:

[0142]

[0143] S35, using the predicted data finally output as control data to perform consistency control.

[0144] In some preferred implementations, the above S3 may further include:

[0145] If the forecast data If the error between the predicted value and the true value is greater than the set threshold, the extreme learning machine is retrained and the above steps S31 to S34 are repeated until the output predicted data meets the error requirement.

[0146] Based on the same inventive concept, an embodiment of the present invention further provides a data packet loss problem consistency control system for microgrid fault recovery.

[0147] Specifically, Figure 4 As shown, the data packet loss problem consistency control system for microgrid fault recovery provided by this embodiment may further include the following modules:

[0148] A consistency control building module, which builds a virtual leader-follower consistency control model based on the hierarchical control architecture of the microgrid system;

[0149] A trigger condition establishment module, which is used to calculate the deviation caused by communication packet loss to the control result of the consistency control model, and select the deviation as the first trigger condition, and set the consistency control overshoot as the second trigger condition;

[0150] A hierarchical control module is used to complete consistency control using the real-time data output by droop control of each DER when the steady-state error of the microgrid system is less than the first trigger condition and the consistency control overshoot is less than the second trigger condition; otherwise, consistency control is completed using the control data output in the prediction compensation link.

[0151] It should be noted that the steps in the method provided by the present invention can be implemented by using the corresponding components in the system, and those skilled in the art can refer to the technical solution of the system to implement the step flow of the method, and can also refer to the technical solution of the method to implement the composition of the system, that is, the embodiments in the system and the embodiments in the method can be understood as preferred examples of each other, which will not be elaborated here.

[0152] An embodiment of the present invention further provides a computer terminal, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the processor can be used to execute any method of the above-mentioned embodiments of the present invention, or to run any system of the above-mentioned embodiments of the present invention.

[0153] Optionally, the memory is used to store programs; the memory may include volatile memory (English: volatile lememory), such as random-access memory (English: random-access memory, abbreviated: RAM), such as static random-access memory (English: static random-access memory, abbreviated: SRAM), double data rate synchronous dynamic random access memory (English: Double Data Rate Synchronous Dynamic Random Access Memory, abbreviated: DDR SDRAM), etc.; the memory may also include non-volatile memory (English: non-volatile memory), such as flash memory (English: flash memory). The memory is used to store computer programs (such as applications, functional modules, etc. that implement the above method), computer instructions, etc., and the above computer programs, computer instructions, etc. can be partitioned and stored in one or more memories. And the above computer programs, computer instructions, data, etc. can be called by the processor.

[0154] The above-mentioned computer programs, computer instructions, etc. may be stored in one or more memories in partitions, and the above-mentioned computer programs, computer instructions, data, etc. may be called by a processor.

[0155] The processor is used to execute the computer program stored in the memory to implement the various steps of the method or various modules of the system involved in the above embodiments. For details, please refer to the relevant descriptions in the above method and system embodiments.

[0156] The processor and the memory may be independent structures or integrated structures. When the processor and the memory are independent structures, the memory and the processor may be coupled and connected via a bus.

[0157] An embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it can be used to execute any method of the above embodiments of the present invention, or to run any system of the above embodiments of the present invention.

[0158] Among them, computer-readable media include computer storage media and communication media, wherein the communication media include any media that facilitates the transmission of computer programs from one place to another. The storage medium can be any available medium that can be accessed by a general or special-purpose computer. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and the storage medium can be located in an ASIC. In addition, the ASIC can be located in a user device. Of course, the processor and the storage medium can also be present in a communication device as discrete components.

[0159] The data packet loss problem consistency control method and system for microgrid fault recovery provided in the above-mentioned embodiment of the present invention firstly adopts an innovative prediction compensation mechanism based on the idea of ​​event triggering, combined with extreme learning machine (ELM) and model predictive control (MPC), aiming to improve the system's responsiveness to dynamic changes. The method can effectively predict the future state of the system and optimize the performance of the system through a compensation control strategy. At the same time, in order to solve the common data packet loss problem during information transmission, the method also proposes a virtual leader-follower consistency control strategy. By introducing the concept of a virtual leader, each node of the system can still maintain consistency through a compensation control strategy when facing data loss, thereby ensuring the overall stability of the system.

[0160] The consistency control method provided by the present invention can effectively solve the communication packet loss problem faced in the hierarchical control of microgrid fault recovery, ensure the overall stability of the system, and greatly improve the control effect of hierarchical control. Hierarchical control is performed on the basis of the consistency control of the present invention, which greatly improves the effect of microgrid fault recovery.

[0161] All matters not covered in the above embodiments of the present invention are well known in the art.

[0162] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A data packet loss problem consistency control method for microgrid fault recovery, characterized in that: include: Based on the hierarchical control architecture of the microgrid system, a virtual leader-follower consistency control model is established; Calculate the deviation of the control result of the consistency control model caused by communication packet loss, select the deviation as the first trigger condition, and set the consistency control overshoot as the second trigger condition; If the steady-state error of the microgrid system is less than the first trigger condition and the consistency control overshoot is less than the second trigger condition, the real-time data output by each DER through droop control is used to complete the consistency control; otherwise, the control data output in the prediction compensation link is used to complete the consistency control.

2. The method for controlling data packet loss consistency for microgrid fault recovery according to claim 1, characterized in that: The hierarchical control architecture based on the microgrid system establishes a virtual leader-follower consistency control model, including: Providing a hierarchical control architecture for a microgrid system; Assume that in the communication network of the hierarchical control architecture, the i-th distributed power source loses packets when transmitting information within a fixed period of time, the i-th distributed power source has N adjacent power sources for communication, the communication connection graph between the i-th distributed power source and the N adjacent power sources includes at least one directed spanning tree, and the virtual leader is set as a globally reachable point; In the microgrid system, the voltage and frequency droop controllers of the i-th distributed generation are designed as follows: In the formula, ω i and U i are the output frequency and voltage of the distributed unit respectively; ω ref and U ref are the frequency reference value and the voltage reference value respectively; m i and n i is the droop coefficient, P i and Q i are the active power and reactive power of the distributed unit respectively; According to the above droop controller design, the virtual leader-follower consistency control design corresponding to the i-th distributed generation is: In the formula, u i is the function corresponding to the virtual leader-follower consistency controller, N i is the set of adjacent power sources of the i-th distributed power source; k xi1 and k xi2 is the undetermined gain factor; x i and x j represents the voltage or frequency of the i-th distributed power source and the j-th distributed power source; a ij is the connection relationship between the i-th distributed power source and the j-th distributed power source, b i is the connection relationship between the virtual leader and the follower. If there is a connection, then b i >0, otherwise b i =0; The virtual leader-follower consensus protocol of the i-th distributed generation taking into account the communication packet loss problem is: In the formula, α i , α j and α L are the packet loss rates of the virtual leaders of distributed power sources; x L is the state quantity of the virtual leader; Under the effect of formula (3), when k xi1 and k xi2 When certain conditions are met, the status of the follower and the virtual leader can always follow each other; Assuming that the state equation of the microgrid system is a first-order equation, we have: in, Perform Laplace transform on equation (4): Where, u1 is the state quantity of the first distributed power source, u2 is the state quantity of the second distributed power source; X(s) is the state quantity after Laplace transformation; x1(t)| t＝0 and x2(t)| t＝0 are the initial values ​​of the output state quantities of the first distributed power source and the second distributed power source droop controller, respectively. The deviation between the output state quantity and the state quantity corresponding to the virtual leader is: At the same time, there are: When the gain coefficient meets the following conditions, the microgrid system can meet the consistency requirements: Where, c1=∫x1(t)dt| t-0 , c2=∫x2(t)dt| t＝0 .

3. The method for controlling data packet loss consistency for microgrid fault recovery according to claim 2, characterized in that: The hierarchical control architecture includes: an information layer and a physical layer; wherein: The information layer includes: a prediction compensation link calculation part, an event trigger mechanism part and a communication network part; The physical layer includes the following interconnected parts: a primary control link, a secondary control link, a power calculation link, a voltage synthesis link, a voltage and current double closed loop link and a PWM signal generator.

4. The method for controlling data packet loss consistency for microgrid fault recovery according to claim 1, characterized in that: The calculating the deviation caused by the communication packet loss on the control result of the consistency control model, selecting the deviation as the first trigger condition, and setting the consistency control overshoot as the second trigger condition, includes: The deviation of the control result of the consistency control model caused by the communication packet loss refers to the degree to which the controlled quantity deviates from the expected value, wherein the controlled quantity is the frequency and voltage output by the distributed power supply droop control, and the expected value is the frequency reference value and the voltage reference value; Taking the i-th distributed power source as the research object, the consistency protocol before and after packet loss is: In the formula, k xi1 and k xi2 is the gain coefficient, α i and α j is the packet loss rate of the first distributed power source and the jth distributed power source, α L is the packet loss rate of the virtual leader; After Laplace transforming equation (11), we have: According to Laplace's differential theorem, integral theorem and final value theorem, we can get: From formula (13), we can get: x i (∞)-x i ′(∞)=Δx i (∞) (14) In the formula, x i (∞) is the state quantity of the i-th distributed unit, x i ′(∞) is the differential value of the ith distributed unit, Δx i (∞) is the deviation caused by communication packet loss; The overshoot at the initial moment of consistency control is taken as the trigger event, and the overshoot is ||∫(VLFCC)dt| t＝初始时刻 |-x L ∣, as the second trigger condition.

5. The method for controlling data packet loss consistency for microgrid fault recovery according to claim 4, characterized in that: Also includes: Based on the first trigger condition and the second trigger condition, a control trigger mechanism is established; wherein: For the i-th distributed power source, the critical values ​​of the first trigger condition and the second trigger condition are set to k respectively. ωi1 and k ωi2 , then the control trigger mechanism is established as follows: when the steady-state error is within the allowable range, that is, the error is less than k ωi1 , and the overshoot of the virtual leader-follower consistency control model is also within the corresponding allowable range, that is, the overshoot is less than k ωi2 At this time, the real-time output data of the distributed power droop control is used to complete the consistency control. Otherwise, the data obtained from the prediction compensation link is used to complete the consistency control.

6. The method for controlling data packet loss consistency for microgrid fault recovery according to claim 1, characterized in that: The use of control data outputted in the prediction compensation link to complete consistency control includes: The prediction and compensation link includes an MPC model and m extreme learning machines; Perform weighted processing on m extreme learning machines, where the i-th extreme learning machine ELM i The weight λ i for: In the formula, e i =y i -y ELMi ,y i is the real data; ELMi is the data output by the i-th extreme learning machine; After weighted processing, the data output by m extreme learning machines is: The weighted data output by the m extreme learning machines are then weighted with the data output by the MPC model predictive control to obtain: In the formula, λ ELM is the weighted coefficient for the extreme learning machine, y MPC The data output by the MPC model predictive control; After combining the output data of m extreme learning machines and the MPC model, the output prediction data is obtained for: The final output prediction data is used as control data for consistency control.

7. The method for controlling data packet loss consistency for microgrid fault recovery according to claim 6, characterized in that: Also includes: When the predicted data If the error between the predicted value and the true value is greater than the set threshold, the extreme learning machine is retrained and the weighted processing process is repeated until the output prediction data meets the error requirement.

8. A data packet loss problem consistency control system for microgrid fault recovery, characterized in that: include: A consistency control building module, which builds a virtual leader-follower consistency control model based on the hierarchical control architecture of the microgrid system; A trigger condition establishment module, which is used to calculate the deviation caused by communication packet loss on the control result of the consistency control model, and select the deviation as the first trigger condition, and set the consistency control overshoot as the second trigger condition; A hierarchical control module is used to complete consistency control using the real-time data output by droop control of each DER when the steady-state error of the microgrid system is less than the first trigger condition and the consistency control overshoot is less than the second trigger condition; otherwise, consistency control is completed using the control data output in the prediction compensation link.

9. A computer terminal comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, it can be used to perform the method described in any one of claims 1 to 7, or to run the system described in claim 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, it can be used to perform the method described in any one of claims 1 to 7, or to run the system described in claim 8.

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