Distributed secondary control method and system for network construction type virtual synchronous machine based on event triggering

Abstract

The invention discloses a distributed secondary control method and a distributed secondary control system for a network-building type virtual synchronous machine based on event triggering, and relates to the technical field of micro-grid secondary control, and the method comprises the steps: building an island micro-grid dynamic model; an event triggering controller is introduced, an event triggering mechanism and time-varying gain control are deeply fused, and communication is triggered through a dynamic threshold function and a non-periodic communication strategy when a current error exceeds a preset threshold; by constraining the error dynamic change rate and setting the error lower bound after triggering, it is ensured that the event triggering interval has the right lower bound, and therefore the Zeno phenomenon is eliminated. An event triggering mechanism and preset time control are deeply fused, and through a dynamic threshold function and a non-periodic communication strategy, the communication burden is remarkably reduced and the Zeno phenomenon is eliminated while the frequency recovery and power distribution precision are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of micro-grid secondary control technology, and particularly relates to a network-structured virtual synchronous machine distributed secondary control method and system based on event triggering. BACKGROUND

[0002] With the increase of new energy penetration, island micro-grid becomes an important solution for power supply in remote areas due to its independent operation capability. The virtual synchronous machine technology significantly improves the stability of power electronic equipment in the micro-grid by simulating the inertia and damping characteristics of the traditional synchronous generator. However, the primary control of the virtual synchronous machine will cause a frequency deviation, which needs to be eliminated by the secondary control to achieve accurate power distribution. At present, the mainstream secondary control strategies include centralized, decentralized and distributed control, among which the distributed control is concerned due to its high robustness and good flexibility.

[0003] The existing distributed secondary control adopts a periodic communication mechanism, that is, the controllers continuously exchange information to achieve consistency. However, the periodic communication has the following defects: 1) waste of communication resources: when the system is in steady state, frequent communication leads to redundant data transmission, occupying bandwidth and increasing communication cost; 2) insufficient real-time performance: high-frequency communication may reduce the control response speed due to network delay or congestion; 3) security risks: continuous communication is vulnerable to malicious attacks, threatening the information security of the system. In order to reduce the communication burden, the event triggering mechanism is introduced into the field of micro-grid control. The event triggering mechanism will determine whether the system communicates at each sampling time according to the occurrence of the event triggered by the condition. The basic principle is to add an event detector and a trigger between the sensors and controllers of each VSG in the island micro-grid. The event detector collects the necessary measurement data at each sampling time and judges whether the current value meets the event triggering condition through calculation. If the triggering condition is met, the trigger will immediately act to make the neighboring nodes communicate and update the controller signal, thereby completing an event triggering. Otherwise, if the triggering condition is not met, the trigger remains static and the controller signal is not updated. Therefore, the event detection link plays a core role in the entire event triggering mechanism. Although the existing research has verified the feasibility of event triggering in the micro-grid, there are still the following problems: 1) complex triggering condition design: most methods need to rely on global information or complex threshold functions, which are difficult to implement; 2) risk of Zeno phenomenon: if the event is triggered infinitely in a limited time, the event triggering mechanism will fail, and the system may collapse due to frequent communication; 3) insufficient combination with predetermined time control: the existing event triggering strategies are mostly for limited time or fixed time control, and do not fully utilize the global convergence characteristics of the predetermined time control, resulting in uncertain disturbance recovery time.

[0004] In summary, the prior art is difficult to reduce the communication volume while taking into account the system dynamic performance and stability. Therefore, there is an urgent need for an efficient and secure distributed secondary control method that can achieve frequency recovery and power distribution within a predetermined time, and significantly reduce communication burden through an event-triggered mechanism. SUMMARY

[0005] The purpose of the present application is to provide an event-triggered network-based virtual synchronous machine distributed secondary control method and system, which addresses the communication redundancy, insufficient dynamic performance and Zeno phenomenon risk of the existing island microgrid distributed secondary control, deeply integrates the event-triggered mechanism and the predetermined time control, and through a dynamic threshold function and a non-periodic communication strategy, significantly reduces the communication burden while ensuring the accuracy of frequency recovery and power distribution, and eliminates the Zeno phenomenon.

[0006] The present application provides an event-triggered network-based virtual synchronous machine distributed secondary control method, comprising: building an island microgrid dynamic model; introducing an event-triggered controller, deeply integrating the event-triggered mechanism and the time-varying gain control, triggering communication through a dynamic threshold function and a non-periodic communication strategy when the current error exceeds the preset threshold; by constraining the error dynamic change rate and setting the error lower bound after triggering, ensuring that the event-triggered interval has a positive lower bound, thereby eliminating the Zeno phenomenon.

[0007] As a preferred, the building an island microgrid dynamic model includes an island microgrid with N virtual synchronous machines (VSGs), and the rotor motion equation of the i-th VSG is as follows: , wherein, J i is the virtual inertia; D i is the damping coefficient; ω i is the output angular frequency; P i is the output active power; P ref，i is the reference active power; ω N is the rated frequency; is the event-triggered control input.

[0008] As a preferred, only at moment is updated, and remains unchanged within interval, that is: , wherein, is the k-th event-triggering moment, is the k+1-th event-triggering moment, is a secondary control input signal, is an event-triggered control input signal.

[0009] As a preference, the deep integration of the event-triggered mechanism and the time-varying gain control includes: configuring a secondary control input signal , wherein, , is a predetermined time-varying gain function, is an error signal under an event-triggered condition, a i、 a j is a parameter for controlling accurate allocation of active power, a ij is an adjacency matrix element, indicating whether i and j have communication or not, g i is a gain coefficient corresponding to the ith DG, used to adjust the influence degree of the control input error e ui on the overall error, N i denotes the neighbor set of DG i , and j denotes the neighbor DG i of DG j .

[0010] As a preference, the introduction of the event-triggered controller includes: setting the first DG in the distributed communication structure as a leader, and setting u ref as the control input variable transmitted by the first DG leader, providing a reference signal for the control input, and providing a reference signal for the DGs other than the first DG leader, and defining e ui as: , defining an event-triggered control input and the error of the continuous control input u i (t) is: , triggering time is determined by the following condition: , wherein, is a trigger sensitivity parameter, used to control the trigger frequency; is a design parameter, satisfying , is an adjustment parameter, g i is a gain coefficient corresponding to the DG i , N i is the number of neighbor nodes, e is a consistency error, satisfying e = u i -u ref , and t is real-time time; is kept constant in the triggering interval, satisfying: .

[0011] As preferred, the time-varying gain control is calculated as follows: , wherein, , is a time-varying gain function, is a preset time-varying function, and b and c are gain coefficients, is a user-defined function, is a preset finite time allowed by physics, and the recovery time length is set by setting the value of , n, is a constant, satisfying , and t0 is a preset time at which the time-varying control starts to act.

[0012] As preferred, the ensuring that the event triggering interval has a positive lower bound by constraining the dynamic change rate of the error and setting a lower bound of the error after triggering includes: DG i has not received an update of the state of the neighbor node, and triggering occurs at the time , ; No new triggering is performed at t, and the sampling error is known as: , from t to is integrated to obtain: , wherein e i is the proportional error of u i , and is calculated in combination with the triggering condition to obtain: .

[0013] The application further provides an event-triggered network-constructed virtual synchronous machine distributed secondary control system, comprising: a model construction module, configured to construct a dynamic model of an island microgrid; a deep fusion module, configured to introduce an event-triggered controller, deeply fuse the event-triggering mechanism and the time-varying gain control, and trigger communication when the current error exceeds a preset threshold through a dynamic threshold function and a non-periodic communication strategy; an anti-Zeno module, configured to ensure that the event triggering interval has a positive lower bound by constraining the dynamic change rate of the error and setting a lower bound of the error after triggering, so as to exclude the Zeno phenomenon.

[0014] As preferred, the dynamic model of the island micro-grid includes N virtual synchronous machines (VSGs) in the island micro-grid, and the rotor motion equation of the i-th VSG is as follows: , wherein J i is a virtual inertia; D i is a damping coefficient; ω i is an output angular frequency; P i is an output active power; P ref，i is a reference active power; ω N is a rated frequency; is an event-triggered control input.

[0015] The application also provides an electronic device, comprising: a memory for storing a processing program; a processor for implementing the event-triggered network-type virtual synchronous machine distributed secondary control method according to the embodiments of the application when executing the processing program.

[0016] The application also provides a computer-readable storage medium for storing computer instructions, which, when executed by a processor, complete the event-triggered network-type virtual synchronous machine distributed secondary control method according to the embodiments of the application.

[0017] The application has the following beneficial effects for the prior art: The application provides an event-triggered network-type virtual synchronous machine distributed secondary control method, which solves the communication redundancy problem caused by traditional continuous periodic sampling and improves the communication efficiency and stability of the system. On the basis of time-distributed control, an event-triggering mechanism is introduced, and communication is triggered only when the system state error exceeds the preset threshold, thereby avoiding the waste of resources caused by periodic communication. By defining the control input error and the sampling error, an event-triggering condition suitable for the leader-follower communication structure is designed, and the triggering mechanism is only set for the follower DG, thereby further reducing the communication amount. The stability of the system is analyzed by means of Lyapunov function, and it is proved that the mechanism can effectively eliminate the Zeno phenomenon and ensure a limited number of triggering times within a limited time.

[0018] Compared with the prior art, the method significantly reduces the communication frequency while ensuring the frequency recovery and accurate power allocation within a predetermined time. Simulation experiments show that, in the load mutation and plug-and-play scene, the system frequency can quickly converge to 50Hz, the active power is allocated according to the preset proportion, and the number of triggering times is reduced by about 60% compared with the traditional continuous communication mode, thereby effectively saving the communication resources and improving the economy and reliability of the system. The research provides an effective solution for the stable operation of the island micro-grid in the communication-limited scene. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A flow chart of a distributed secondary control method of a network-constructed virtual synchronous machine based on event triggering in an embodiment of the present application; Figure 2 A communication topology of an island microgrid in an embodiment of the present application; Figure 3 A structure diagram of an event-triggering controller in an embodiment of the present application; Figures 4-5 A frequency waveform diagram before and after adding event triggering in an embodiment of the present application; Figures 6-7 A frequency and power response waveform diagram in a load mutation scenario in an embodiment of the present application; Figure 8 A frequency and power response waveform diagram in a plug-and-play scenario in an embodiment of the present application. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of the present application.

[0021] The term “comprising” and variations thereof as used in the present application are open-ended, that is, “including but not limited to”. The term “based on” is “at least partially based on”. The term “one embodiment” means “at least one embodiment”; the term “another embodiment” means “at least one additional embodiment”; the term “some embodiments” means “at least some embodiments”. Related definitions of other terms will be given in the following description.

[0022] It should be noted that the concepts of “first”, “second”, etc. mentioned in the present application disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0023] It should be noted that the modification of “one” or “multiple” mentioned in the present application disclosure is illustrative but not limiting, and those skilled in the art should understand that, unless otherwise explicitly indicated in the context, it should be understood as “one or more”.

[0024] As shown in Figure 1 The present application provides a distributed secondary control method of a network-constructed virtual synchronous machine based on event triggering, which comprises the following steps: S1: constructing an island microgrid dynamic model; S2: Introduce an event-triggered controller, deeply integrate the event-triggering mechanism with the time-varying gain control, trigger the communication when the current error exceeds the preset threshold through a dynamic threshold function and a non-periodic communication strategy; S3: By constraining the dynamic change rate of the error and setting the lower bound of the error after triggering, ensure that the event-triggering interval has a positive lower bound, thereby excluding the Zeno phenomenon.

[0025] The event-triggered mechanism adopted in this embodiment triggers communication only when the error exceeds the dynamic threshold, avoiding the redundancy of periodic communication, significantly reducing the communication frequency between nodes in the distributed system, and being particularly suitable for the communication resource-limited island microgrid environment; The non-periodic communication strategy breaks the fixed time communication mode, further optimizes the communication opportunity, reduces the network load and delay, and improves the real-time performance of the system; By using the pre-determined time-varying gain function, the control input intensity is dynamically adjusted to accelerate the error convergence and ensure that the system reaches a stable state within a preset time; The triggering threshold is adjusted adaptively according to the system state to balance the control accuracy and communication frequency, and to avoid excessive conservatism or frequent triggering; By limiting the error change rate, it is ensured that the interval between two triggers has a positive lower bound, which theoretically eliminates the possibility of infinite triggering, avoids continuous triggering caused by instantaneous error return to zero, and ensures the practical feasibility of the triggering interval. This scheme combines the event-triggered mechanism with the time-varying gain control to significantly reduce the communication cost while ensuring the control performance, and excludes the Zeno phenomenon through strict theoretical constraints, ultimately realizing the efficient, stable and robust operation of the island microgrid, and providing a lightweight and practical solution for the distributed virtual synchronous machine coordinated control.

[0026] In one embodiment, the step S1 of constructing the dynamic model of the island microgrid includes an island microgrid with N virtual synchronous machines (VSGs), and the rotor motion equation of the i-th VSG is as follows: , wherein J i is the virtual inertia; D i is the damping coefficient; ω i is the output angular frequency; P i is the output active power; P ref，i is the reference active power; ω N is the rated frequency, f N = 50 Hz; is the event-triggered control input signal, which simulates the inertia and damping of the traditional synchronous generator through the virtual inertia J i and the damping coefficient D i , provides frequency support when the load is disturbed, suppresses frequency fluctuations, and improves the transient stability of the island microgrid. Based on the rotor motion equation, the output active power P iFast tracking of reference value P ref,i , maintaining power balance.

[0027] Rewriting of secondary control input signal , only updating at , and remaining unchanged within , that is: , wherein, is the kth event trigger time, is the k+1th event trigger time, is the secondary control input signal, is the event trigger control input signal, indicating that the event trigger control input signal will maintain the value of the previous moment before the second trigger, avoiding periodic communication and continuous calculation, significantly reducing the communication frequency between distributed VSGs and the controller calculation burden, breaking the fixed time communication mode, triggering the control signal update only when the error exceeds the dynamic threshold, optimizing the utilization of communication resources, and being particularly suitable for communication-limited island microgrids.

[0028] In an embodiment, the step S2 of deeply integrating the event trigger mechanism with the time-varying gain control includes: configuring the secondary control input signal , wherein, , is a predetermined time-varying gain function, is an error signal under event trigger condition, a i , a j is a parameter for controlling accurate distribution of active power, ij is an adjacency matrix element, indicating whether i and j have communication or not, i is the gain coefficient corresponding to the ith DG, used to adjust the influence degree of the control input error e ui on the overall error, i N i indicates the neighbor set of DG i , and j indicates the neighbor DG j . By using the adjacency matrix element a ij and the neighbor set N i , the coordinated distribution of active power among DGs is realized based on local communication, and the microgrid power balance is maintained. Through the parameters a i , a j and the gain coefficient g i, flexible regulation of the control weight of each DG, balance tracking error and power distribution accuracy, avoid local shock. Based on the neighbor state of distributed control strategy, without centralized decision, single node failure does not affect the global operation, improve the reliability of the system.

[0029] The step S2 of introducing the event-triggered controller specifically includes the following steps: The first DG in the distributed communication structure is set as the leader, and u ref is set as the control input variable transmitted by the first DG leader, and the reference signal of the control input is provided, and the reference signal is provided for the DGs except the first DG leader. It can be understood that only the first DG will set a global reference u ref , and other DGs will follow this reference and gradually approach this reference value. The leader-distributed structure here is essentially to reduce communication, and there is no need to transmit the global reference u ref to each DG.

[0030] Define e ui as: , Define the error between the event-triggered control input u and the continuous control input u i (t) as: , The triggering time is determined by the following condition: , wherein, is a triggering sensitivity parameter for controlling the triggering frequency; is a design parameter, satisfying , is an adjustment parameter, g i is the gain coefficient corresponding to the DG i , N i is the number of neighbor nodes, e is the consistency error, satisfying e=u i -u ref , t is the real-time time; Remain constant within the triggering interval, satisfying: .

[0031] Those skilled in the art can understand that the above triggering rule is that the current error is greater than the sampling error, that is, the error exceeds the threshold value, then u i is triggered to update, otherwise u iInvariable, the event trigger mechanism is deeply integrated with the predetermined time control depth, through the dynamic threshold function and the non-periodic communication strategy, the frequency recovery and the power distribution precision are guaranteed.

[0032] In an embodiment, the time-varying gain control is calculated as follows: , Wherein, , is a time-varying gain function, is a preset time-varying function, b and c are gain coefficients, is a user-defined function, is a preset limited time allowed by any physics, the recovery time is set by setting the value of n, is a constant, satisfying t0 is a preset time when the secondary control starts to work.

[0033] Once the Zeno phenomenon occurs, the trigger mechanism will fail. In order to exclude the Zeno phenomenon, it is necessary to prove that there is a time lower bound greater than 0 between any two starting intervals, that is, according to the definition of event trigger, the designed event trigger mechanism needs to ensure that there is no infinite trigger in a limited time, so it is proved that there is a time lower bound between any two event intervals, which can exclude the Zeno phenomenon. In step S3, the error dynamic change rate is constrained and the error lower bound after triggering is set to ensure that the event trigger interval has a positive lower bound, that is, the time interval between two triggering events must be greater than a fixed positive number, that is, there is a minimum time interval > 0, which cannot infinitely approach to zero, which specifically includes: In the two event triggering moments, DG i No neighbor node state update is received, and triggering occurs at ; ; No new triggering is performed at t, and according to the sampling error: , From t to Integrating the following: , Wherein, e i is the proportional error of u i , combined with the triggering condition, the following is obtained: , Wherein, is the proportional error after event triggering, and the following is obtained: That is, the error always has a lower bound, and after each triggering, the error cannot infinitely approach to 0, so the Zeno phenomenon can be excluded.

[0034] This embodiment proposes an event-triggered distributed secondary control strategy for islanded microgrid with virtual synchronous machines, aiming to solve the communication redundancy problem caused by traditional continuous periodic sampling and improve the communication efficiency and stability of the system. On the basis of time-distributed control, an event-triggering mechanism is introduced, which only triggers communication when the system state error exceeds the preset threshold, avoiding the waste of resources caused by periodic communication. By defining the control input error and sampling error, an event-triggering condition suitable for leader-follower communication structure is designed, and only the follower DG is set with the triggering mechanism, further reducing the communication volume. With the help of Lyapunov function analysis, the system stability is analyzed, and it is proved that the mechanism can effectively eliminate the Zeno phenomenon and ensure a limited number of triggering times within a limited time. Compared with the prior art, this method significantly reduces the communication frequency while ensuring the frequency recovery and accurate power allocation within the predetermined time. Simulation experiments show that under the load mutation and plug-and-play scenarios, the system frequency can quickly converge to 50Hz, the active power is allocated according to the preset proportion, and the number of triggering times is reduced by about 60% compared with the traditional continuous communication mode, effectively saving communication resources and improving the economy and reliability of the system. This research provides an effective solution for the stable operation of islanded microgrid in communication-limited scenarios.

[0035] To verify the actual control effect of the proposed time-triggering mechanism, a communication topology as shown in FIG. 1 is used for verification simulation. Figure 2 FIG. 2 is a structure diagram of the event-triggered controller, Figure 3 Table 1 shows the inverter and bottom controller parameters of the four DGs as follows: Table 1 Inverter control parameters

[0036] In all experiments, DG1 is set as the leader to perform event-triggering on the remaining three DG units, and load mutation and plug-and-play tests are performed. The active power allocation ratio is set as P1:P2:P3:P4=1:2:1:2. The total simulation time is 4s, and the predetermined recovery time is set to 0.5s. The reference frequency is set to 50Hz.

[0037] This embodiment is a microgrid composed of four virtual synchronous machines for islanded operation. At the beginning of the simulation, only the primary control works. At t=1s, the distributed event-triggered secondary control based on the predetermined time is connected; at t=2s, the device DG4 is switched on and the load mutation test is performed; at t=3s, the device is disconnected and the load mutation test is performed.

[0038] Figures 4-5The frequency waveforms before and after the event-triggered secondary control method is added are shown. By comparing, it can be seen that the effect of the predetermined time recovery is unchanged, the system frequency is recovered within the set 0.5s, but due to the addition of the event-triggered control, the original predetermined time control system parameters need to be expanded according to the actual situation to achieve the predetermined time control effect.

[0039] Further, the performance of the control strategy proposed in the application is further verified in the load mutation scenario. Figures 6-7 The frequency and power response waveform of the event-triggered control strategy is given, and Table 2 gives the event-triggered times of the DG under the load change: Table 2 Event-triggered times of DG in load mutation scenario

[0040] The predetermined time is set to 0.5s. Before 1s, the system only works under the action of the first control, and the event-triggered secondary control is started at 1s, from Figure 6 It can be seen that the frequency is restored to the reference value f ref =50Hz at 1.5s, the active power distribution ratio is accurately distributed according to the set ratio P1:P2:P3:P4=1:2:1:2 within 0.5s, the predetermined time control can be realized, and the frequency recovery and accurate distribution of active power are realized. In the process of 2s and 3s, the load is connected and disconnected, the output frequency and active power of the island microgrid can be stably set to the reference value under the setting of the predetermined time, and the active power is distributed according to the new load capacity with P1:P2:P3:P4=1:2:1:2, so the designed control strategy is effective in the case of load mutation.

[0041] Finally, in the plug-and-play scenario, the connection between DG4 and the microgrid system is disconnected, simulating the situation of equipment being put into and disconnected, as shown in Figure 8 The secondary control is started at 1s, the frequency and power respond quickly, DG4 is disconnected at 2s, the secondary controller can be restored to 50Hz within the set 0.5s and maintained, the power is redistributed according to the preset P1:P2:P3:P4=1:2:1:2, and the system still works normally at 3s, which means that the control objectives of frequency recovery and accurate power distribution are completed, and the preset event distributed secondary control still acts on the system in the global range. The triggering times of all DGs are listed in Table 3 as follows: Table 3 Event-triggered times of DG in plug-and-play scenario

[0042] The results show that the proposed event triggering mechanism has good plug-and-play characteristics, and can flexibly cope with device and load switching during system operation, ensuring the stability and reliability of the system.

[0043] Therefore, the embodiment of the present application adopts the above-mentioned event-triggered distributed secondary control method of the virtual synchronous machine of the island micro-grid, and utilizes limited aperiodic communication to reduce the communication burden of the system.

[0044] Based on the same concept, the present application provides an event-triggered network-based virtual synchronous machine distributed secondary control system, comprising: a model construction module for constructing a dynamic model of an island micro-grid; a deep fusion module for introducing an event-triggered controller, deeply fusing the event-triggered mechanism with the time-varying gain control, and triggering communication through a dynamic threshold function and a non-periodic communication strategy when the current error exceeds the preset threshold; a Zeno-resistant module for ensuring the existence of a positive lower bound of the event-triggering interval by constraining the dynamic change rate of the error and setting a lower bound of the error after triggering, thereby eliminating the Zeno phenomenon.

[0045] The construction of the dynamic model of the island micro-grid includes N virtual synchronous machines (VSGs) in the island micro-grid, and the rotor motion equation of the i-th VSG is as follows: , wherein, J i is the virtual inertia; D i is the damping coefficient; ω i is the output angular frequency; P i is the output active power; P ref，i is the reference active power; ω N is the rated frequency; is the event-triggered control input.

[0046] It should be noted that the division of each module in the device / system embodiment is only a logical function division, and all or part of the modules can be integrated into one physical entity, or can be physically separated. And these modules can all be implemented in the form of software called by a processing element; or all can be implemented in the form of hardware; or part of the units can be implemented in the form of software called by a processing element, and part of the units can be implemented in the form of hardware.

[0047] The implementation principle of the above-mentioned modules has been described in the foregoing method embodiment, and therefore will not be repeated here.

[0048] Based on the same concept, in some embodiments of the present application, an electronic device is also provided. The electronic device comprises a memory and a processor. The memory is configured to store a processing program, and the processor is configured to execute the processing program according to the instructions. When the processor executes the processing program, the event-triggered meshed virtual synchronous machine distributed secondary control method in the foregoing embodiments is implemented.

[0049] In some embodiments of the present application, a readable storage medium is also provided. The readable storage medium can be a non-volatile readable storage medium or a volatile readable storage medium. The readable storage medium stores instructions. When the instructions are executed on a computer, an electronic device comprising the readable storage medium executes the event-triggered meshed virtual synchronous machine distributed secondary control method in the foregoing embodiments.

[0050] It can be understood that, for the event-triggered meshed virtual synchronous machine distributed secondary control method mentioned above, if each is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for making a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the embodiments of the method of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (Read-only memory, ROM), a random access memory (Random access memory, RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0051] The computer readable storage medium can include a data signal carried in the baseband or as part of a carrier wave propagating through the program code. Such a propagating data signal can take various forms, including but not limited to an electromagnetic signal, an optical signal, or any suitable combination of the above. The readable storage medium can also be any readable medium other than the readable storage medium, which can send, propagate or transmit programs for use by or in conjunction with an instruction execution system, device or apparatus. The program code contained on the readable storage medium can be transmitted by any suitable medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination of the above.

[0052] The program code for carrying out the techniques disclosed herein can be written in any combination of one or more programming languages, including an object oriented programming language such as Python, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computing device, partly on the user's computing device, as a stand-alone software package, partly on the user's computing device and partly on a remote computing device or entirely on the remote computing device or server. In the latter scenario, the remote computing device can be connected to the user's computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computing device, such as through the Internet using an Internet Service Provider.

[0053] Finally, it should be noted that the above-mentioned embodiments are merely used to illustrate the technical solutions of the present application, rather than limit the present application; even though the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent replacements; and these modifications or replacements do not cause the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An event-triggered network-forming virtual synchronous machine distributed secondary control method, characterized in that, include: Construct a dynamic model of an isolated microgrid; An event-triggered controller is introduced, which deeply integrates the event triggering mechanism with time-varying gain control. Communication is triggered when the current error exceeds a preset threshold through a dynamic threshold function and an aperiodic communication strategy. By constraining the dynamic rate of error change and setting a lower bound for the error after triggering, a positive lower bound is ensured for the event triggering interval, thereby eliminating the Zeno phenomenon.

2. The event-triggered network-forming virtual synchronous machine distributed secondary control method according to claim 1, characterized in that, The dynamic model of the islanded microgrid includes an islanded microgrid with N virtual synchronous generators (VSGs). The rotor motion equation of the i-th VSG is as follows: ， where J i is the virtual inertia; D i is the damping coefficient; ω i is the output angular frequency; P i is the output active power; P ref，i is the reference active power; ω N is the rated frequency; is the event-triggered control input.

3. The distributed secondary control method for a network-based virtual synchronous machine based on event triggering according to claim 2, characterized in that, only when is updated, and remains constant for intervals, i.e.: ， wherein, is the kth event-triggering time, is the k+1th event-triggering time, is the quadratic control input signal, is the event-triggered control input signal.

4. The event-triggered network-forming virtual synchronous machine distributed secondary control method according to claim 1, characterized in that, The deep integration of the event triggering mechanism with time-varying gain control includes: Configuring secondary control input signals , where, , is a predetermined time-varying gain function, is the error signal under event-triggered condition, a i、 a j is a parameter to control the accurate allocation of active power, a ij is an element of the adjacency matrix, indicating whether i and j have communication or not, g i is the gain coefficient corresponding to the ith DG, used to adjust the influence degree of the control input error e ui on the overall error, N i denotes the neighbor set of DG i , j denotes the neighbor DG i of DG j .

5. The event-triggered network-forming virtual synchronous machine distributed secondary control method according to claim 1, characterized in that, The introduced event trigger controller includes: Set the first DG in the distributed communication structure as the leader, set u ref The control input variable transmitted for the first DG leader, provide the reference signal of the control input, provide the reference signal for the DGs except the first DG leader, define e ui is: ， Defining event-triggered control input with continuous control input u i The error of (t) is: ， triggering moment is determined by the following conditions: ， wherein, is a triggering sensitivity parameter for controlling the triggering frequency; is a design parameter satisfying , is an adjustment parameter, g i is a DG i is a corresponding gain coefficient, N i is a number of neighbor nodes, e is a consistency error satisfying e = u i - u ref t is a real-time time; The following holds true within the trigger interval, which remains constant: 。 6. The event-triggered network-forming virtual synchronous machine distributed secondary control method according to claim 1, characterized in that, The time-varying gain control is calculated as follows: ， wherein, , is a time-varying gain function, is a preset time-varying function, and b and c are gain coefficients, is a user-defined function, is a preset finite time allowed by physics, and the recovery duration is set by setting the value of , n, is a constant, and satisfies t0is a preset time at which the secondary control starts to act.

7. The event-triggered networking-based virtual synchronous machine distributed secondary control method according to claim 1, characterized in that, The step of ensuring a positive lower bound for the event triggering interval by constraining the dynamic rate of error change and setting a lower bound for the error after triggering includes: Between two event trigger instants, the DG i an update of the state of the neighbor node is not received, and in case a trigger occurs at an instant ; If no new trigger is performed, the sampling error can be known: ， From t to Integrating gives: , where e i is the proportional error of u i , and the trigger condition is calculated as follows: 。 8. An event-triggered network-forming virtual synchronous machine distributed secondary control system, characterized in that, include: The model building module is used to build dynamic models of isolated microgrids; The deep fusion module is used to introduce an event-triggered controller, which deeply integrates the event-triggered mechanism with time-varying gain control. It triggers communication when the current error exceeds a preset threshold through a dynamic threshold function and an aperiodic communication strategy. The anti-Zeno module is used to ensure that there is a positive lower bound for the event trigger interval by constraining the dynamic rate of error change and setting a lower bound for the error after triggering, thereby eliminating the Zeno phenomenon.

9. The event-triggered networking-based virtual synchronous machine distributed secondary control system according to claim 8, characterized in that, The dynamic model of the islanded microgrid includes an islanded microgrid with N virtual synchronous generators (VSGs). The rotor motion equation of the i-th VSG is as follows: ， where J i is the virtual inertia; D i is the damping coefficient; ω i is the output angular frequency; P i is the output active power; P ref，i is the reference active power; ω N is the rated frequency; is the event-triggered control input.

10. An electronic device, comprising: include: The memory is used to store the processing program; A processor, which, when executing the processing program, implements the event-triggered network-type virtual synchronous machine distributed secondary control method as described in any one of claims 1 to 7.

11. A computer readable storage medium, characterized in that, Used to store computer instructions, which, when executed by a processor, complete the event-triggered distributed secondary control method for a networked virtual synchronous machine as described in any one of claims 1-7.

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