Microgrid fixed time dynamic event trigger control method based on observer

Abstract

The invention provides a micro-grid fixed time dynamic event trigger control method based on an observer, and belongs to the technical field of micro-grid operation control. The control method comprises the following steps: judging whether the voltage and frequency of primary droop control of a power control variable of an ith DG unit in the time-delay island micro-grid deviate from reference values or not, if so, performing secondary control, and if not, performing secondary droop control; by designing a voltage recovery variable, a frequency recovery variable and an active power recovery variable of micro-grid fixed time dynamic event trigger control based on an observer, the output voltage and the output frequency of a distributed generator are recovered to reference values within convergence time. According to the optimization method, the fixed-time dynamic event triggering observer with the confidence factor observes the transmission delay state, the adverse effect of delay on the control performance is limited, operation of each DG unit in the micro-grid is coordinated, the control performance of the micro-grid is guaranteed, and the stability of the system is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of microgrid operation control, and in particular relates to a fixed-time dynamic event triggering observer control method for a time-delay microgrid. Background Art

[0002] As a small power supply and distribution system, microgrid consists of distributed generators, energy storage systems and loads, and can operate in grid-connected and islanded operation modes. Usually, microgrids operate in grid-connected mode. When a fault or maintenance occurs, the microgrid operates in islanded mode to achieve uninterrupted power supply and ensure the power supply reliability of the system through appropriate control schemes. Traditional droop control is easily affected by line impedance characteristics, causing the output voltage and frequency of the microgrid system to deviate from the reference value. In order to ensure the stability of the output voltage and frequency of the distributed generation unit of the island microgrid, a distributed consistency secondary control strategy can be used to compensate for the deviation of the output voltage and frequency of the island microgrid droop control. Considering that the voltage and frequency stability control of the microgrid usually has strict real-time requirements, the convergence time of the asymptotic consistency control strategy is usually not finite, and the convergence time of the finite time consistency control is limited by the initial state of the system. Fixed time consistency control can make the system consistent within a finite time, and is not affected by the initial state of the system, and can adapt to the real-time stability control requirements of the voltage and frequency of the microgrid.

[0003] At present, the secondary voltage and frequency control method of isolated microgrid based on distributed fixed time control is widely used. There are both academic papers that have made in-depth theoretical analysis on this, and there are also engineering methods for practical application, such as the invention patent application "Distributed Fixed Time Coordinated Control Method for Isolated Microgrid" (CN 107465211B) and the paper "Distributed Finite Time Event Triggered Secondary Coordinated Control of Isolated Microgrid" (Zhou Jianping, Zhang Jian, Mao Dajun, Ge Xiangyi, Ye Jianqiao, Fang Le. Distributed Finite Time Event Triggered Secondary Coordinated Control of Isolated Microgrid [J] ~ Electric Power Automation Equipment, 2021, 41(11): 127-132).

[0004] The Chinese invention patent application CN 107465211 B, published on September 1, 2020, is a method for adjusting the output frequency and output voltage of an isolated microgrid using fixed-time consistency control to restore the voltage and frequency to a reference value within a fixed time. However, this method has the following shortcomings:

[0005] 1) The isolated island distributed secondary control needs to transmit information through a sparse communication network. The communication delay generated during the communication process will reduce the control performance of the microgrid. This method does not consider the communication delay and its corresponding solution;

[0006] 2) The continuous control of microgrids requires a large amount of control resources. As the scale of microgrid systems continues to expand, in order to save control resources and reduce the control burden, it is necessary to adopt an event-triggered control method. This method ignores the waste of resources caused by continuous control;

[0007] In 2021, the paper "Distributed finite-time event-triggered secondary coordinated control of isolated microgrids" (Zhou Jianping, Zhang Jian, Mao Dajun, Ge Xiangyi, Ye Jianqiao, Fang Le. Distributed finite-time event-triggered secondary coordinated control of isolated microgrids [J]. Electric Power Automation Equipment, 2021, 41(11): 127-132). The authors proposed to use a distributed finite-time event-triggered control method to adjust and control the output voltage and frequency of the isolated microgrid, achieving voltage and frequency stability in a limited time while saving control resources. However, this method has the following shortcomings:

[0008] 1) The isolated island distributed secondary control needs to transmit information through a sparse communication network. The communication delay generated during the communication process will reduce the control performance of the microgrid. This method does not consider the communication delay and its corresponding solution;

[0009] 2) The convergence time of finite-time stability control usually depends on the initial state of the system, which is usually not easy to obtain;

[0010] 3) The event triggering conditions used are static and cannot be changed with changes in the external environment. They cannot minimize the number of event triggering and save control resources. Summary of the invention

[0011] The problem to be solved by the present invention is the real-time control and continuous control problems of the existing time-delay island microgrid, and further provides a microgrid fixed-time dynamic event triggering control method based on an observer, which ensures the control performance of the time-delay microgrid while saving control resources.

[0012] The object of the present invention is achieved in this way. The present invention provides a method for triggering a fixed-time dynamic event in a microgrid based on an observer, wherein the microgrid is an island microgrid, comprising N DG units and 3 loads, and any one of the N DG units is recorded as DG i , i is the serial number of the DG unit, i = 1, 2, ..., N, N is a positive integer; the DG i It consists of a DC power supply Ui and an inverter, and the first N-1 DG i The output end is connected to DG through the power line i+1 The output end of DG1 is connected to the output end of DG N-1 The output terminal and DG N The output end of each DG is connected to a load through a power line.i There is a distributed controller installed on the N DG i There is a direct or indirect communication relationship between them through distributed controllers, and any two DGs that have a direct communication relationship i The communication between them is two-way;

[0013] The control structure of the distributed controller consists of two parts: primary control and secondary control. The primary control part includes droop control, and the secondary control is a distributed fixed-time dynamic event trigger control based on an observer. The primary control and the secondary control jointly achieve the output voltage and frequency stability of the island microgrid. The specific control steps are as follows:

[0014] Step 1: Given DG i Output rated voltage E ni and rated frequency ω ni ; DG i The output voltage generated by the primary droop control at the operating time t is recorded as the primary droop output voltage E i (t), DG i The frequency generated by the primary droop control at the operating time t is recorded as the primary droop frequency ω i (t), its expression distribution is:

[0015] E i (t) = E ni -k qi Q i (t)

[0016] ω i (t) = ω ni -k pi P i (t)

[0017] In the formula, Q i (t) is the reactive power output by the distributed generator DGi at the operating time t, P i (t) is the distributed generator DG i The active power output at the operating time t, k qi For DG i Voltage droop control coefficient at operating time t, k pi For DG i The frequency droop control coefficient at the operating time t;

[0018] Step 2: Start the secondary control and use Artstein transformation to perform delay compensation control to design the distributed fixed-time dynamic event-triggered voltage observer control quantity. and distributed fixed-time dynamic event-triggered frequency observer control Control quantity of distributed fixed-time dynamic event-triggered active power observer

[0019] Step 3: When the first voltage dynamic event triggering condition is met, the voltage observation value Convergence time of voltage observer control Internal satisfaction E ref is the voltage reference value; when the first frequency dynamic event trigger condition is met, the frequency observation value Convergence time in frequency observation control Internal satisfaction ω ref is the frequency reference value; when the first active power dynamic event trigger condition is met, the active power observation value Convergence time of active power observation control Internal satisfaction Where j is the serial number of the DG unit, j = 1, 2, ..., N, and i ≠ j. The DG unit corresponding to j is recorded as DG j , k pj For DG j The frequency droop control coefficient at the operating time t; For DG j The corresponding active power observation value;

[0020] The voltage observation control convergence time Frequency Observation Control Convergence Time and active power observation control convergence time The expressions are:

[0021]

[0022]

[0023] In the formula, h ij is the communication delay time, ε is the trigger parameter, ε∈(0,1), α is the first fixed time power index, β is the second fixed time power index, β>1>α>0, is the first voltage weighting parameter of the distributed fixed-time dynamic event trigger observer, is the second voltage weighting parameter of the distributed fixed-time dynamic event trigger observer, is the first voltage observer gain coefficient, is the second voltage observer gain coefficient, is the first voltage observer dynamic event trigger variable gain coefficient, The second voltage observer dynamic event trigger variable gain coefficient, is the voltage observer trigger parameter, is the first weighted undirected graph The Laplacian-like matrix, is the second weighted undirected graph The Laplacian-like matrix, for The second smallest positive eigenvalue of for The second smallest positive eigenvalue of ij Indicates DG i and DG j The communication coupling coefficient between them is that if DGi can receive DG j , then a ij =1, otherwise, a ij =0; a i0 For DG i The coupling coefficient of the received reference value, a i0 =g i , g i For DG i Positioning gain, if DG i Can obtain system reference voltage information, then g i =1, otherwise g i =0;

[0024] is the first frequency weighting parameter of the distributed fixed-time dynamic event-triggered observer, is the second frequency weighting parameter of the distributed fixed-time dynamic event trigger observer, is the first frequency observer gain coefficient, is the second frequency observer gain coefficient, is the first frequency observer dynamic event trigger variable gain coefficient, is the dynamic event trigger variable gain coefficient of the second frequency observer, is the frequency observer trigger parameter,

[0025] is the first active power weighting parameter of the distributed fixed-time dynamic event-triggered observer, is the second active power weighting parameter of the distributed fixed-time dynamic event-triggered observer, is the first active power observer gain coefficient, is the gain coefficient of the second active power observer, is the first active power observer dynamic event trigger variable gain coefficient, is the dynamic event trigger variable gain coefficient of the second active power observer, is the active power observer trigger parameter,

[0026] Step 4: Design the voltage recovery control variable u triggered by the fixed-time dynamic event based on the observer Ei (t), frequency recovery variable u ωi (t) and active power distribution control variable u Pi (t);

[0027] Step 5: When the triggering condition of the second voltage dynamic event is met, the secondary control is used to realize the microgrid primary droop voltage E within a limited time T(E). i (t) Tracking voltage observation value When the second frequency dynamic event triggering condition is met, the primary droop frequency ω of the microgrid is realized within a limited time T(ω). i (t) Tracking frequency observation value When the triggering condition of the second active power dynamic event is met, the primary active power of the microgrid is reduced to P within a limited time T(P). i (t) Tracking active power observations

[0028] The expressions of the voltage recovery control convergence time T(E), the frequency recovery control convergence time T(ω) and the active power distribution control convergence time T(P) are respectively:

[0029]

[0030]

[0031] In the formula, is the observer-based fixed-time dynamic event triggering first voltage weighting parameter, is the observer-based fixed-time dynamic event triggering second voltage weighting parameter, c E1 is the first voltage controller gain, c E2 The second voltage controller gain, c E4 is the first voltage controller dynamic event trigger variable gain coefficient, c E5 is the voltage controller dynamic event trigger variable gain coefficient, c E is the voltage controller trigger parameter, c E ∈(0,1);

[0032] is the first frequency weighting parameter for the observer-based fixed-time dynamic event trigger, The second frequency weighting parameter is triggered for the observer-based fixed-time dynamic event, c ω1 is the first frequency controller gain, c ω2is the second frequency controller gain, c ω4 is the first frequency controller dynamic event trigger variable gain coefficient, c ω5 Second frequency controller dynamic event trigger variable gain coefficient, c ω is the frequency controller trigger parameter, c ω ∈(0,1);

[0033] is the observer-based fixed-time dynamic event triggering first active power weighting parameter, is the second active power weighting parameter triggered by the observer-based fixed-time dynamic event, c P1 is the first active power control gain, c P2 is the second active power control gain, c P4 is the first active power distribution controller dynamic event trigger variable gain coefficient, c P5 is the dynamic event trigger variable gain coefficient of the second active power distribution controller, c P is the trigger parameter of the active power distribution controller, c P ∈(0,1);

[0034] Step 6, turn off secondary control.

[0035] Preferably, the distributed fixed-time dynamic event triggering voltage observer control variable in step 2 The expression is:

[0036]

[0037] In the formula, For DG i The current voltage dynamic event triggering moment, For DG i The next voltage dynamic event triggers, and k is the sequence number of the dynamic event triggering time, For DG i The output observed voltage at the current voltage dynamic event triggering moment The state value after Artstein transformation, For DG j The output voltage observed at The state value after Artstein transformation, For DG i exist The voltage observation value, For DG j exist The voltage observation value of When i, j∈[1, N]; aij Indicates DG i and DG j The communication coupling coefficient between them is i Able to receive DG j , then a ij =1, otherwise, a ij =0; a i0 For DG i The coupling coefficient of the received reference value, a i0 =g i , g i For DG i Positioning gain, if DG i Can obtain system reference voltage information, then g i =1, otherwise g i =0;ξ ij (t) is the confidence factor, 0≤ξ ij (t)≤1, tanh() is the hyperbolic tangent function, Triggering hyperbolic tangent function voltage parameters for distributed fixed-time dynamic events, is the third voltage observer gain coefficient;

[0038] The distributed fixed-time dynamic event-triggered frequency observer controls the variable The expression is:

[0039]

[0040] In the formula, For DG i The current frequency dynamic event triggering moment, For DG i The next frequency dynamic event trigger time, and For DG i The output observation frequency is at the current frequency dynamic event triggering moment The state value after Artstein transformation, For DG j The output observation frequency is at the current frequency dynamic event triggering moment The state value after Artstein transformation, in, For DG i At the moment when the current frequency dynamic event is triggered The frequency observation value of For DG j At the moment when the current frequency dynamic event is triggered The frequency observation value of i, j ∈ [1, N]; is the confidence factor, Triggering hyperbolic tangent function frequency parameters for distributed fixed-time dynamic events, is the third frequency observer gain coefficient;

[0041] The distributed fixed-time dynamic event triggers the active power observer to control the variable The control variable expression is:

[0042]

[0043] In the formula, For DG i The current active power dynamic event triggering time, For DG i The next active power dynamic event triggering time, and For DG i The output observed active power at the current active power dynamic event triggering moment The state value after Artstein transformation, For DG j The state value of the output observed active power after Artstein transformation at the current active power dynamic event triggering moment, in, For DG i At the current active power dynamic event triggering moment The active power observation value of For DG j At the current active power dynamic event triggering moment The observed value of active power; i, j ∈ [1, N]; is the confidence factor, The distributed fixed-time dynamic event triggers the hyperbolic tangent function active power parameter, is the gain coefficient of the third active power observer.

[0044] Preferably, in step 3, the first voltage dynamic event triggering condition refers to the event triggering condition of the distributed fixed-time dynamic event triggering voltage observer, and the specific expression is:

[0045]

[0046] In the formula, For DG i The voltage observer trigger function y i (t) is the voltage observation value state error, is the voltage observer trigger parameter, ξ i(t) is the measurement error of the distributed fixed-time dynamic event-triggered voltage observer, is the derivative of the internal dynamic event-triggered variable of the distributed fixed-time dynamic event-triggered voltage observer, Γ i (t) is the internal dynamic event trigger variable of the distributed fixed-time dynamic event trigger voltage observer, Trigger variable derivatives for voltage internal dynamic events parameter, When satisfied Condition, event trigger, DG i The control protocol updates the status information, otherwise it is not triggered; A third voltage observer dynamic event trigger variable gain coefficient;

[0047] The distributed fixed-time dynamic event-triggered voltage observer excludes Zeno behavior, and the dynamic event triggering time interval is:

[0048]

[0049] In the formula, The first time interval parameter for the distributed fixed-time voltage dynamic event trigger, The second time interval parameter for the distributed fixed-time voltage dynamic event trigger,

[0050]

[0051] The first frequency dynamic event triggering condition refers to the event triggering condition of the distributed fixed-time dynamic event triggering frequency observer, and the specific expression is:

[0052]

[0053] In the formula, For DG i The frequency observer trigger function is is the frequency observation state error, is the frequency observer trigger parameter, Measuring error for a distributed fixed-time dynamic event-triggered frequency observer, is the derivative of the internal dynamic event trigger variable of the distributed fixed-time dynamic event trigger frequency observer, is the internal dynamic event trigger variable of the distributed fixed-time dynamic event trigger frequency observer, Trigger derivatives for frequency internal dynamic events parameter, When satisfied Condition, event trigger, DG i The control protocol updates the status information, otherwise it is not triggered; A dynamic event trigger variable gain coefficient for a third frequency observer;

[0054] The distributed fixed-time dynamic event trigger frequency observer excludes Zeno behavior, and the event trigger time interval is:

[0055]

[0056] In the formula, The first time interval parameter for the distributed fixed time frequency dynamic event trigger, The second time interval parameter for distributed fixed time frequency dynamic event triggering,

[0057] The first active power dynamic event triggering condition refers to the event triggering condition of the distributed fixed-time dynamic event triggering the active power observer:

[0058]

[0059] In the formula, For DG i The active power observer trigger function is is the active power observation state error, is the active power observer trigger parameter, The measurement error of the distributed fixed-time dynamic event-triggered active power observer, is the derivative of the internal dynamic event-triggered variable of the distributed fixed-time dynamic event-triggered active power observer, Triggering dynamic event variables inside the active power observer for distributed fixed-time dynamic events;

[0060] Internal dynamic event trigger for active power parameter, When satisfied Condition, event trigger, DG i The control protocol updates the status information, otherwise it is not triggered; is a dynamic event trigger variable gain coefficient of the third active power observer;

[0061] The distributed fixed-time dynamic event-triggered active power observer excludes Zeno behavior, and the event triggering time interval is:

[0062]

[0063] In the formula, The first time interval parameter for the distributed fixed-time active power dynamic event triggering, The second time interval parameter for the distributed fixed-time active power dynamic event triggering,

[0064] Preferably, the voltage recovery control variable u triggered by the fixed-time dynamic event based on the observer in step 4 is Ei The expression of (t) is as follows:

[0065]

[0066] In the formula, For DG i The current voltage dynamic event triggering moment, For DG i The next voltage dynamic event triggers, and e Ei (t) is the distributed generator DG in the island microgrid at time t i The voltage observation value and output voltage E i (t) The state error between The voltage parameter of the hyperbolic tangent function is triggered by the fixed-time dynamic event based on the observer, c E3 is the third voltage controller gain;

[0067] The frequency recovery control variable u is triggered by the fixed-time dynamic event based on the observer. ωi The expression of (t) is:

[0068]

[0069] In the formula, For DG i The current frequency dynamic event triggering moment, For DG i The next frequency dynamic event trigger time, and e ωi (t) is the DG in the isolated microgrid at time t i The frequency observation value of and output frequency ω i (t) The state error between The frequency parameter of the hyperbolic tangent function is triggered for the fixed-time dynamic event based on the observer, c ω3 is the third frequency controller gain;

[0070] The active power distribution control variable u triggered by the fixed-time dynamic event based on the observer Pi The expression of (t) is:

[0071]

[0072] In the formula, For DG i The current active power dynamic event triggering time, For DG i The next active power dynamic event triggering time, and e Pi (t) is the DG in the isolated microgrid at time t i The active power observation value And the output active power P i (t) The state error between is the active power parameter of the hyperbolic tangent function triggered by the fixed-time dynamic event based on the observer, c P3 is the third active power control gain.

[0073] Preferably, the second voltage dynamic event triggering condition in step 5 refers to an event triggering condition for triggering a voltage controller based on a fixed-time dynamic event of an observer, and the specific expression is:

[0074]

[0075] In the formula, Φ Ei (t) is DG i The voltage controller trigger function, Φ Ei (t) = θ E (|ξ Ei (t)|-c E c E1 |e Ei (t)| α -c E c E2 |e Ei (t)| β -c E c E3 ) is, θ E is the voltage controller trigger parameter, θ E >0,ξ Ei (t) is the voltage measurement error triggered by a fixed-time dynamic event based on the observer, is the derivative of the internal dynamic event trigger variable based on the fixed-time observer dynamic event trigger, Γ Ei (t) is the internal dynamic event trigger variable based on the fixed-time dynamic event trigger of the observer, γ E Trigger for voltage internal dynamic events Parameter, γ E ∈(0,1), when Φ Ei (t)≥Γ Ei (t) condition, event trigger, DG i The control protocol updates the status information, otherwise it will not be triggered; c E6 a variable gain coefficient for a third voltage controller dynamic event trigger;

[0076] The observer-based fixed-time dynamic event-triggered voltage controller excludes Zeno behavior, and the event triggering time interval is:

[0077]

[0078] In the formula, ρ E1 (0) is the first time interval parameter for triggering a fixed-time voltage dynamic event based on an observer, ρ E2 (0) is the second time interval parameter triggered by the fixed-time voltage dynamic event based on the observer,

[0079] The second frequency dynamic event triggering condition refers to the event triggering condition of the frequency controller triggered by a fixed-time dynamic event based on an observer, and the specific expression is:

[0080]

[0081] In the formula, Φ ωi (t) is DG i The frequency controller trigger function, φ ωi (t) = θ ω (|ξ ωi (t)|-c ω c ω1 |e ωi (t)| α -c ω c ω2 |e ωi (t)| β -c ω c ω3 ), θ ω is the frequency controller trigger parameter, θ ω >0,ξ ωi (t) is the error of the fixed-time dynamic event-triggered frequency controller based on the observer, is the derivative of the internal dynamic event trigger variable based on the fixed-time observer dynamic event trigger, Γωi (t) is the internal dynamic event trigger variable based on the fixed-time dynamic event trigger of the observer, γ ω Triggering derivatives for internal dynamic events Parameter, γ ω ∈(0,1), when Φ ωi (t)≥Γ ωi (t) condition, event trigger, DG i The control protocol updates the status information, otherwise it will not be triggered; c ω6 The third frequency controller dynamic event trigger variable gain coefficient;

[0082] The observer-based fixed-time dynamic event-triggered frequency controller excludes Zeno behavior, and the event-triggered time interval is:

[0083]

[0084] In the formula, ρ ω1 (0) is the first time interval parameter for triggering a dynamic event based on a fixed time frequency observer, ρ ω2 (0) is the second time interval parameter for triggering a dynamic event based on a fixed time frequency observer,

[0085] The second active power dynamic event triggering condition refers to an event triggering condition for triggering an active power controller based on a fixed-time dynamic event of an observer, and the specific expression is:

[0086]

[0087] In the formula, Φ Pi (t) is DG i The trigger function of the active power distribution controller Φ Pi (t) = θ P (|ξ Pi (t)|-c P c P1 |e Pi (t)| α -c P c P2 |e Pi (t)| β -c P c P3 ), θ P is the trigger parameter of active power distribution controller, θ P >0,ξ Pi (t) is the active power measurement error triggered by the fixed-time dynamic event based on the observer, is the derivative of the internal dynamic event trigger variable of the observer-based fixed-time dynamic event trigger active power, Γ Pi (t) is the internal dynamic event trigger variable of active power triggered by fixed-time dynamic events based on observer, γ P Trigger variable derivative for active power internal dynamic events Parameter, γ P ∈(0,1), when Φ Pi (t)≥Γ Pi (t) condition, event trigger, DG i The control protocol updates the status information, otherwise it will not be triggered; c P6 A dynamic event trigger variable gain coefficient for the third active power distribution controller;

[0088] The observer-based fixed-time dynamic event-triggered active power distribution controller excludes Zeno behavior, and the event triggering time interval is:

[0089]

[0090] In the formula, ρ P1 (0) is the first time interval parameter for triggering the active power dynamic event based on the fixed time observer, ρ P2 (0) is the second time interval parameter triggered by the fixed-time active power dynamic event based on the observer,

[0091] Compared with the prior art, the present invention has the following beneficial effects:

[0092] 1. In the distributed fixed-time dynamic event-triggered control, the distributed secondary control of the isolated island microgrid needs to transmit information through a sparse communication network. The communication delay generated during the communication process will reduce the control performance of the microgrid. A distributed fixed-time dynamic event-triggered observer with a confidence factor is used to observe the transmission delay state, limit the adverse effect of delay on control performance, and thus improve the performance of the time-delayed isolated island microgrid.

[0093] 2. The continuous control of the microgrid requires a large amount of control resources. With the continuous expansion of the scale of the microgrid system, in order to save control resources and reduce the control burden, a dynamic event-triggered control method is adopted to reduce the waste of control resources. On the basis of fixed-time dynamic event-triggered control, a hyperbolic tangent function is added to further reduce the event triggering time and controller update frequency, saving control resources.

[0094] 3. Taking communication delay into consideration, the observer and dynamic event triggering technology are adopted. The operation of each DG unit in the microgrid is coordinated by using the observer to observe the dynamic event triggering information of each DG unit and the neighbor information obtained by communication, so as to restore the voltage and frequency to the reference value within the preset fixed time, ensure the control performance of the microgrid, and improve the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Figure 1 is a topological diagram of an island microgrid in an embodiment of the present invention;

[0096] Figure 2 The distributed generator DG in the embodiment of the present invention i Control block diagram of

[0097] Figure 3 The distributed generator DG in the embodiment of the present invention i The control flow diagram of

[0098] Figure 4 is a communication topology diagram between DG units based on graph theory in an embodiment of the present invention;

[0099] Figure 5 is a simulation diagram of the output voltage of each DG unit in an embodiment of the present invention;

[0100] Figure 6 It is a triggering time simulation diagram of the distributed fixed-time dynamic event-triggered voltage observer control of each DG unit in an embodiment of the present invention;

[0101] Figure 7 is a triggering time simulation diagram of the observer-based dynamic event-triggered voltage control of each DG unit in an embodiment of the present invention;

[0102] Figure 8 is a simulation diagram of the output frequency of each DG unit in an embodiment of the present invention;

[0103] Fig. 9 It is a triggering time simulation diagram of the distributed fixed-time dynamic event triggering frequency observer control of each DG unit in an embodiment of the present invention;

[0104] Fig.10 It is a triggering time simulation diagram of the observer-based dynamic event triggering frequency control of each DG unit in an embodiment of the present invention;

[0105] Fig.11 is a simulation diagram of the output active power of each DG unit in an embodiment of the present invention;

[0106] Fig.12 It is a simulation diagram of the triggering time of the distributed fixed-time dynamic event-triggered active power observer control of each DG unit in an embodiment of the present invention;

[0107] Fig.13 It is a triggering time simulation diagram of the observer-based dynamic event-triggered active power control of each DG unit in the embodiment of the present invention. DETAILED DESCRIPTION

[0108] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings.

[0109] Figure 1 is a topological diagram of an isolated island microgrid implemented in the present invention, Figure 4 is a communication topology diagram between DG units based on graph theory in an embodiment of the present invention, consisting of Figure 1 and Figure 4 It can be seen that the microgrid described in the present invention is an island microgrid, which includes N DG units and 3 loads. Any one of the N DG units is recorded as DG i , i is the serial number of the DG unit, i=1, 2, ..., N, N is a positive integer. i It consists of a DC power supply U and an inverter, and the first N-1 DG i The output end is connected to DG through the power line i+1 The output end of DG1 is connected to the output end of DG N-1 The output terminal and DG N The output end of each DG is connected to a load through a power line. i There is a distributed controller installed on the N DG i There is a direct or indirect communication relationship between them through distributed controllers, and any two DGs that have a direct communication relationship i The communication between them is two-way.

[0110] Figure 2 DG in the implementation of the present invention i The control block diagram of Figure 3 Is the invention implemented in DG i The control flow diagram is composed of Figure 2 and Figure 3 It can be seen that the present invention provides a microgrid fixed-time dynamic event triggering control method based on an observer. The control structure of the distributed controller included in the control method consists of two parts: primary control and secondary control. The primary control part includes droop control, and the secondary control is a distributed fixed-time dynamic event triggering control based on an observer. The primary control and the secondary control jointly realize the output voltage and frequency stability of the isolated island microgrid. The specific control steps are as follows:

[0111] Step 1: Given DG i Output rated voltage E ni and rated frequency ω ni; DG i The output voltage generated by the primary droop control at the operating time t is recorded as the primary droop output voltage E i (t), DG i The frequency generated by the primary droop control at the operating time t is recorded as the primary droop frequency ω i (t), its expression distribution is:

[0112] E i (t) = E ni -k qi Q i (t)

[0113] ω i (t) = ω ni -k pi P i (t)

[0114] In the formula, Q i (t) is the distributed generator DG i The reactive power output at the operating time t, P i (t) is the distributed generator DG i The active power output at the operating time t, k qi For DG i Voltage droop control coefficient at operating time t, k pi For DG i Frequency droop control coefficient at operating time t.

[0115] Step 2: Start the secondary control and use Artstein transformation to perform delay compensation control to design the distributed fixed-time dynamic event-triggered voltage observer control quantity. and distributed fixed-time dynamic event-triggered frequency observer control Control Quantity of Distributed Fixed-Time Dynamic Event-Triggered Active Power Observer

[0116] Step 3: When the first voltage dynamic event triggering condition is met, the voltage observation value Convergence time of voltage observer control Internal satisfaction E ref is the voltage reference value; when the first frequency dynamic event trigger condition is met, the frequency observation value Convergence time in frequency observation control Internal Satisfaction ω ref is the frequency reference value; when the first active power dynamic event trigger condition is met, the active power observation value Convergence time of active power observation control Internal satisfaction Where j is the serial number of the DG unit, j = 1, 2, ..., N, and i ≠ j. The DG unit corresponding to j is recorded as DG j , k pj For DG j The frequency droop control coefficient at the operating time t; For DG j The corresponding active power observation value.

[0117] The voltage observation control convergence time Frequency Observation Control Convergence Time and active power observation control convergence time The expressions are:

[0118]

[0119] In the formula, h ij is the communication delay time, ε is the trigger parameter, ε∈(0,1), α is the first fixed time power index, β is the second fixed time power index, β>1>α>0, is the first voltage weighting parameter of the distributed fixed-time dynamic event trigger observer, is the second voltage weighting parameter of the distributed fixed-time dynamic event trigger observer, is the first voltage observer gain coefficient, is the second voltage observer gain coefficient, is the first voltage observer dynamic event trigger variable gain coefficient, The second voltage observer dynamic event trigger variable gain coefficient, is the voltage observer trigger parameter, is the first weighted undirected graph The Laplacian-like matrix, is the second weighted undirected graph The Laplacian-like matrix, for The second smallest positive eigenvalue of for The second smallest positive eigenvalue of ij Indicates DG i and DG j The communication coupling coefficient between them is i Able to receive DG j , then a ij =1, otherwise, a ij =0; a i0 For DG i The coupling coefficient of the received reference value, a i0 =g i , gi For DG i Positioning gain, if DG i Can obtain system reference voltage information, then g i =1, otherwise g i =0.

[0120] is the first frequency weighting parameter of the distributed fixed-time dynamic event-triggered observer, is the second frequency weighting parameter of the distributed fixed-time dynamic event trigger observer, is the first frequency observer gain coefficient, is the second frequency observer gain coefficient, is the first frequency observer dynamic event trigger variable gain coefficient, is the dynamic event trigger variable gain coefficient of the second frequency observer, is the frequency observer trigger parameter,

[0121] is the first active power weighting parameter of the distributed fixed-time dynamic event-triggered observer, is the second active power weighting parameter of the distributed fixed-time dynamic event-triggered observer, is the first active power observer gain coefficient, is the gain coefficient of the second active power observer, is the first active power observer dynamic event trigger variable gain coefficient, is the dynamic event trigger variable gain coefficient of the second active power observer, is the active power observer trigger parameter,

[0122] Step 4: Design the voltage recovery control variable u triggered by the fixed-time dynamic event based on the observer Ei (t), frequency recovery variable u ωi (t) and active power distribution control variable u Pi (t).

[0123] Step 5: When the triggering condition of the second voltage dynamic event is met, the secondary control is used to realize the microgrid primary droop voltage E within a limited time T(E). i (t) Tracking voltage observation value When the second frequency dynamic event triggering condition is met, the primary droop frequency ω of the microgrid is realized within a limited time T(ω). i (t) Tracking frequency observation value When the triggering condition of the second active power dynamic event is met, the primary active power of the microgrid is reduced to P within a limited time T(P). i (t) Tracking active power observations

[0124] The expressions of the voltage recovery control convergence time T(E), the frequency recovery control convergence time T(ω) and the active power distribution control convergence time T(P) are respectively:

[0125]

[0126] In the formula, is the observer-based fixed-time dynamic event triggering first voltage weighting parameter, is the observer-based fixed-time dynamic event triggering second voltage weighting parameter, c E1 is the first voltage controller gain, c E2 The second voltage controller gain, c E4 is the first voltage controller dynamic event trigger variable gain coefficient, c E5 is the voltage controller dynamic event trigger variable gain coefficient, c E is the voltage controller trigger parameter, c E ∈(0,1);

[0127] is the first frequency weighting parameter for the observer-based fixed-time dynamic event trigger, The second frequency weighting parameter is triggered for the observer-based fixed-time dynamic event, cω1 is the first frequency controller gain, c ω2 is the second frequency controller gain, c ω4 is the first frequency controller dynamic event trigger variable gain coefficient, c ω5 Second frequency controller dynamic event trigger variable gain coefficient, c ω is the frequency controller trigger parameter, c ω ∈(0,1).

[0128] is the observer-based fixed-time dynamic event triggering first active power weighting parameter, is the second active power weighting parameter triggered by the observer-based fixed-time dynamic event, is the first active power control gain, c P2 is the second active power control gain, c P4 is the first active power distribution controller dynamic event trigger variable gain coefficient, c P5 is the dynamic event trigger variable gain coefficient of the second active power distribution controller, cP is the trigger parameter of the active power distribution controller, c P ∈(0,1).

[0129] Step 6, turn off secondary control.

[0130] In this embodiment, the distributed fixed-time dynamic event trigger voltage observer control variable The expression is:

[0131]

[0132] In the formula, For DG i The current voltage dynamic event triggering moment, For DG i The next voltage dynamic event triggers, and k is the sequence number of the dynamic event triggering time, For DG i The output observed voltage at the moment when the current voltage dynamic event is triggered The state value after Artstein transformation, For DG j The output voltage observed at The state value after Artstein transformation, For DG i exist The voltage observation value, For DG j exist The voltage observation value of When i, j∈[1, N]; a ij Indicates DG i and DG j The communication coupling coefficient between them is i Able to receive DG j , then a ij =1, otherwise, a ij =0; a i0 For DG i The coupling coefficient of the received reference value, a i0 =g i , g i For DG i Positioning gain, if DG i Can obtain system reference voltage information, then g i =1, otherwise g i =0;ξ ij (t) is the confidence factor, 0≤ξ ij (t)≤1, tanh() is the hyperbolic tangent function, Triggering hyperbolic tangent function voltage parameters for distributed fixed-time dynamic events, is the gain coefficient of the third voltage observer.

[0133] The distributed fixed-time dynamic event-triggered frequency observer controls the variable The expression is:

[0134]

[0135] In the formula, For DG i The current frequency dynamic event triggering moment, For DG i The next frequency dynamic event trigger time, and For DG i The output observation frequency is at the current frequency dynamic event triggering moment The state value after Artstein transformation, For DG j The output observation frequency is at the current frequency dynamic event triggering moment The state value after Artstein transformation, in, For DG i At the moment when the current frequency dynamic event is triggered The frequency observation value of For DG j At the moment when the current frequency dynamic event is triggered The frequency observation value of i, j ∈ [1, N]; is the confidence factor, Triggering hyperbolic tangent function frequency parameters for distributed fixed-time dynamic events, is the third frequency observer gain coefficient.

[0136] The distributed fixed-time dynamic event triggers the active power observer to control the variable The control variable expression is:

[0137]

[0138] In the formula, For DG i The current active power dynamic event triggering time, For DG i The next active power dynamic event triggering time, and For DG i The output observed active power at the current active power dynamic event triggering moment The state value after Artstein transformation, For DG j The state value of the output observed active power after Artstein transformation at the current active power dynamic event triggering moment, in, For DG i At the current active power dynamic event triggering moment The active power observation value of For DG j At the current active power dynamic event triggering moment The observed value of active power; i, j ∈ [1, N]; is the confidence factor, The distributed fixed-time dynamic event triggers the hyperbolic tangent function active power parameter, is the gain coefficient of the third active power observer.

[0139] In this embodiment, the first voltage dynamic event triggering condition in step 3 refers to the event triggering condition of the distributed fixed-time dynamic event triggering voltage observer, and the specific expression is:

[0140]

[0141] In the formula, For DG i The voltage observer trigger function y i (t) is the voltage observation value state error, is the voltage observer trigger parameter, ξ i (t) is the measurement error of the distributed fixed-time dynamic event-triggered voltage observer, is the derivative of the internal dynamic event-triggered variable of the distributed fixed-time dynamic event-triggered voltage observer, Γ i (t) is the internal dynamic event trigger variable of the distributed fixed-time dynamic event trigger voltage observer, Trigger variable derivatives for voltage internal dynamic events parameter, When satisfied Condition, event trigger, DG i The control protocol updates the status information, otherwise it is not triggered; A variable gain coefficient is triggered for a third voltage observer dynamic event.

[0142] The distributed fixed-time dynamic event-triggered voltage observer excludes Zeno behavior, and the dynamic event triggering time interval is:

[0143]

[0144] In the formula, The first time interval parameter for the distributed fixed-time voltage dynamic event trigger, The second time interval parameter for the distributed fixed-time voltage dynamic event trigger,

[0145] The first frequency dynamic event triggering condition refers to the event triggering condition of the distributed fixed-time dynamic event triggering frequency observer, and the specific expression is:

[0146]

[0147] In the formula, For DG i The frequency observer trigger function is is the frequency observation state error, is the frequency observer trigger parameter, Measuring error for a distributed fixed-time dynamic event-triggered frequency observer, is the derivative of the internal dynamic event trigger variable of the distributed fixed-time dynamic event trigger frequency observer, is the internal dynamic event trigger variable of the distributed fixed-time dynamic event trigger frequency observer, Trigger derivatives for frequency internal dynamic events parameter, When satisfied Condition, event trigger, DG i The control protocol updates the status information, otherwise it is not triggered; Dynamic event trigger variable gain coefficient for the third frequency observer.

[0148] The distributed fixed-time dynamic event trigger frequency observer excludes Zeno behavior, and the event trigger time interval is:

[0149]

[0150] In the formula, The first time interval parameter for the distributed fixed time frequency dynamic event trigger, The second time interval parameter for distributed fixed time frequency dynamic event triggering,

[0151] The first active power dynamic event triggering condition refers to the event triggering condition of the distributed fixed-time dynamic event triggering the active power observer:

[0152]

[0153] In the formula, For DG i The active power observer trigger function is is the active power observation value state error, is the active power observer trigger parameter, The measurement error of the distributed fixed-time dynamic event-triggered active power observer, is the derivative of the internal dynamic event-triggered variable of the distributed fixed-time dynamic event-triggered active power observer, The internal dynamic event trigger variable of the active power observer is triggered by the distributed fixed-time dynamic event.

[0154] Internal dynamic event trigger for active power parameter, When satisfied Condition, event trigger, DG i The control protocol updates the status information, otherwise it is not triggered; It is the dynamic event trigger variable gain coefficient of the third active power observer.

[0155] The distributed fixed-time dynamic event-triggered active power observer excludes Zeno behavior, and the event triggering time interval is:

[0156]

[0157] In the formula, The first time interval parameter for the distributed fixed-time active power dynamic event triggering, The second time interval parameter for the distributed fixed-time active power dynamic event triggering,

[0158] In this embodiment, the voltage recovery control variable u is triggered by the fixed-time dynamic event of the observer in step 4. Ei The expression of (t) is as follows:

[0159]

[0160] In the formula, For DG i The current voltage dynamic event triggering moment, For DG i The next voltage dynamic event triggers, and e Ei(t) is the voltage observation value of the distributed generator DGi in the isolated microgrid at time t and output voltage E i (t) The state error between The voltage parameter of the hyperbolic tangent function is triggered by the fixed-time dynamic event based on the observer, c E3 is the third voltage controller gain.

[0161] The frequency recovery control variable u is triggered by the fixed-time dynamic event based on the observer. ωi The expression of (t) is:

[0162]

[0163] In the formula, For DG i The current frequency dynamic event triggering moment, For DG i The next frequency dynamic event trigger time, and e ωi (t) is the DG in the isolated microgrid at time t i The frequency observation value of and output frequency ω i (t) The state error between The frequency parameter of the hyperbolic tangent function is triggered for the fixed-time dynamic event based on the observer, c ω3 is the third frequency controller gain.

[0164] The active power distribution control variable u triggered by the fixed-time dynamic event based on the observer Pi The expression of (t) is:

[0165]

[0166] In the formula, For DG i The current active power dynamic event triggering time, For DG i The next active power dynamic event triggering time, and e Pi (t) is the DG in the isolated microgrid at time t i The active power observation value And the output active power P i (t) The state error between is the active power parameter of the hyperbolic tangent function triggered by the fixed-time dynamic event based on the observer, cP3 is the third active power control gain.

[0167] In this embodiment, the second voltage dynamic event triggering condition in step 5 refers to an event triggering condition for triggering a voltage controller based on a fixed-time dynamic event of an observer, and the specific expression is:

[0168]

[0169] In the formula, Φ Ei (t) is DG i The voltage controller trigger function, Φ Ei (t) = θ E (|ξ Ei (t)|-c E c E1 |e Ei (t)| α -c E c E2 |e Ei (t)| β -c E c E3 ) is, θ E is the voltage controller trigger parameter, θ E >0,ξ Ei (t) is the voltage measurement error triggered by a fixed-time dynamic event based on the observer, is the derivative of the internal dynamic event trigger variable based on the fixed-time observer dynamic event trigger, Γ Ei (t) is the internal dynamic event trigger variable based on the fixed-time dynamic event trigger of the observer, γ E Trigger for voltage internal dynamic events Parameter, γ E ∈(0,1), when Φ Ei (t)≥Γ Ei (t) condition, event trigger, DG i The control protocol updates the status information, otherwise it will not be triggered; c E6 The variable gain coefficient is triggered for the third voltage controller dynamic event.

[0170] The observer-based fixed-time dynamic event-triggered voltage controller excludes Zeno behavior, and the event triggering time interval is:

[0171]

[0172] In the formula, ρ E1 (0) is the first time interval parameter for triggering a fixed-time voltage dynamic event based on an observer, ρ E2 (0) is the second time interval parameter triggered by the fixed-time voltage dynamic event based on the observer,

[0173] The second frequency dynamic event triggering condition refers to the event triggering condition of the frequency controller triggered by a fixed-time dynamic event based on an observer, and the specific expression is:

[0174]

[0175] In the formula, Φ ωi (t) is DG i The frequency controller trigger function, Φ ωi (t) = θ ω (|ξ ωi (t)|-c ω c ω1 |e ωi (t)| α -c ω c ω2 |e ωi (t)| β -c ω c ω3 ), θ ω is the frequency controller trigger parameter, θ ω >0,ξ ωi (t) is the error of the fixed-time dynamic event-triggered frequency controller based on the observer, is the derivative of the internal dynamic event trigger variable based on the fixed-time observer dynamic event trigger, Γω i (t) is the internal dynamic event trigger variable based on the fixed-time dynamic event trigger of the observer, γ ω Triggering derivatives for internal dynamic events Parameter, γ ω ∈(0,1), when Φ ωi (t)≥Γ ωi (t) condition, event trigger, DG i The control protocol updates the status information, otherwise it will not be triggered; c ω6 Dynamic event trigger variable gain factor for the third frequency controller.

[0176] The observer-based fixed-time dynamic event-triggered frequency controller excludes Zeno behavior, and the event-triggered time interval is:

[0177]

[0178] In the formula, ρω1 (0) is the first time interval parameter for triggering a dynamic event based on a fixed time frequency observer, ρ ω2 (0) is the second time interval parameter for triggering a dynamic event based on a fixed time frequency observer,

[0179] The second active power dynamic event triggering condition refers to an event triggering condition for triggering an active power controller based on a fixed-time dynamic event of an observer, and the specific expression is:

[0180]

[0181] In the formula, Φ Pi (t) is DG i The trigger function of the active power distribution controller Φ Pi (t) = θ P (|ξ Pi (t)|-c P C P1 |e Pi (t)| α -c P c P2 |e Pi (t)| β -c P C P3 ), θ P is the trigger parameter of active power distribution controller, θ P >0,ξ Pi (t) is the active power measurement error triggered by the fixed-time dynamic event based on the observer, is the derivative of the internal dynamic event trigger variable of the observer-based fixed-time dynamic event trigger active power, Γ Pi (t) is the internal dynamic event trigger variable of active power triggered by fixed-time dynamic events based on observer, γ P Trigger variable derivative for active power internal dynamic events Parameter, γ P ∈(0,1), when Φ Pi (t)≥Γ Pi (t) condition, event trigger, DG i The control protocol updates the status information, otherwise it will not be triggered; c P6 The dynamic event trigger variable gain coefficient of the third active power distribution controller.

[0182] The observer-based fixed-time dynamic event-triggered active power distribution controller excludes Zeno behavior, and the event triggering time interval is:

[0183]

[0184] In the formula, ρ P1 (0) is the first time interval parameter for triggering the active power dynamic event based on the fixed time observer, ρ P2 (0) is the second time interval parameter triggered by the fixed-time active power dynamic event based on the observer,

[0185] In this embodiment, the distributed fixed-time dynamic event-triggered voltage observer trigger parameter is The gain coefficient of the first voltage observer is: The gain coefficient of the second voltage observer is The third voltage observer gain coefficient is: The first voltage observer dynamic event trigger variable gain coefficient The second voltage observer dynamic event trigger variable gain coefficient The third voltage observer dynamic event trigger variable gain coefficient The voltage internal dynamic event triggers the variable derivative The parameters are The voltage observer trigger parameter is The voltage parameter of the distributed fixed-time dynamic event triggering hyperbolic tangent function is: The fixed-time dynamic event-triggered voltage controller gain coefficient based on the observer is c E =0.5, the first voltage controller gain c E1 =100, the second voltage controller gain is c E2 =100, the third voltage controller gain c E3 =100, the first voltage controller dynamic event trigger variable gain coefficient c E4 =0.9, the second voltage controller dynamic event trigger variable gain coefficient c E5 =1, the third voltage controller dynamic event trigger variable gain coefficient c E6 =5, the voltage controller internal dynamic event trigger variable derivative The parameter is γ E =0.15, the voltage controller trigger parameter is θ E =0.2, the fixed time dynamic event based on the observer triggers the hyperbolic tangent function voltage parameter The voltage confidence factor is ξ ij (t)=1.

[0186] In this embodiment, the trigger parameter of the distributed fixed-time dynamic event trigger frequency observer is The first frequency observer gain coefficient is The second frequency observer gain coefficient is The third frequency observer gain coefficient is The first frequency observer dynamic event trigger variable gain coefficient The second frequency observer dynamic event trigger variable gain coefficient The third frequency observer dynamic event trigger variable gain coefficient The frequency of internal dynamic events triggering derivatives The parameters are The frequency observer trigger parameter is The frequency parameter of the distributed fixed-time dynamic event triggering hyperbolic tangent function is: The fixed-time dynamic event trigger frequency controller gain coefficient based on the observer is c ω =0.5, the first frequency controller gain c ω1 =100, the second frequency controller gain is c ω2 =100, the third frequency controller gain c ω3 =100, the first frequency controller dynamic event trigger variable gain coefficient c ω4 =0.9, the second frequency controller dynamic event trigger variable gain coefficient c ω5 =0.5, the third frequency controller dynamic event trigger variable gain coefficient c ω6 =4.3, the frequency controller internal dynamic event trigger derivative The parameter is γ ω =0.15, the frequency controller trigger parameter is θ ω =0.2, the fixed-time dynamic event-triggered hyperbolic tangent function frequency controller parameters based on the observer are The frequency confidence factor is

[0187] In this embodiment, the distributed fixed-time dynamic event triggering active power observer trigger parameter is The gain coefficient of the first active power observer is The gain coefficient of the second active power observer is The third active power observer gain coefficient is The first active power observer dynamic event trigger variable gain coefficient The second active power observer dynamic event trigger variable gain coefficient The third active power observer dynamic event trigger variable gain coefficient The active power internal dynamic event triggers the derivative The parameters are The active power observer trigger parameter is The distributed fixed-time dynamic event-triggered hyperbolic tangent function active power parameter is: The fixed-time dynamic event-triggered active power controller gain coefficient based on the observer is c P =0.5, the first active power controller gain c P1 =100, the gain of the second active power controller is c P2 =100, the third active power controller gain c P3 =100, the first active power controller dynamic event trigger variable gain coefficient c P4 =0.9, the second active power controller dynamic event trigger variable gain coefficient c P5 =1, the third active power controller dynamic event trigger variable gain coefficient c P6 =4.3, the internal dynamic event trigger derivative of the active power controller The parameter is γ P =0.15, the active power controller trigger parameter is θ P =0.2, the fixed time dynamic event based on the observer triggers the active power parameter of the hyperbolic tangent function The active power confidence factor is

[0188] In order to prove the beneficial effects of the present invention, the present invention is verified.

[0189] A simulation model of an isolated microgrid is constructed using the MATLAB / Simulink simulation platform. The reference voltage amplitude of the isolated microgrid is set to 311V and the reference frequency is set to 50Hz. The first fixed time power index is α=0.6 and the second fixed time power index is β=1.8. The communication network connection relationship between each DG unit is established through Figure 4 The communication topology diagram in Figure 1 is shown in Figure 2. In this simulation model, only the DG1 unit receives the information of the system reference voltage and reference frequency.

[0190] In the simulated island microgrid, the communication delay h ij =5ms, the simulation process is divided into two stages: at 0-1 seconds, only primary control is performed; at 1-4 seconds, the control method of the present invention is applied, wherein at t=2.5s, load 3 is connected to the microgrid, and at t=4 seconds, load 3 is disconnected from the microgrid. The simulation results of the present invention are shown in Figure 2. Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 , Fig.10 , Fig.11 Fig.12 and Fig.13 shown.

[0191] from Figure 5 It can be seen that the proposed observer-based fixed-time dynamic event-triggered control method for a microgrid, at 0-1 second, the primary control maintains the voltage and frequency stability of the microgrid, but the voltage and frequency are far from the reference value; at 1-4 seconds, the control method of the present invention is applied, and it can be seen that the output voltage deviation of the microgrid is restored to the reference value within a limited time of approximately 0.2 seconds.

[0192] Figure 6 and Figure 7 Four distributed generation DGs were shown i The triggering time of the unit within 0.5 seconds shows that dynamic event triggering control can reduce the number of triggers and significantly reduce the frequency of controller updates. Figure 6 and Figure 7 No continuous triggering phenomenon was found in the simulation, which ruled out the Zeno behavior. The simulation results verified the correctness of the theoretical analysis.

[0193] Figure 8 , Fig. 9 , Fig.10 , Fig.11 , Fig.12 and Fig.13 The DG frequency and active power response curves of the proposed method and the results of the triggering time are shown respectively. It can be seen that the proposed frequency controller can achieve accurate frequency recovery and active power distribution of all DGs within a limited time. In addition, each DG in the microgrid does not exhibit Zeno behavior. Therefore, combined with Figure 5 , Figure 6 and Figure 7 The results show that the effectiveness of the proposed dynamic event-triggered fixed-time control method has been verified.

[0194] The above simulation results show that the proposed observer-based microgrid fixed-time dynamic event triggering control method adopts a state observer with a confidence factor and a dynamic event triggering control method under the condition of considering communication delay, and realizes the coordinated operation of each DG unit in the microgrid by utilizing the measurement information of each DG unit and the neighbor information obtained in the communication. Within the preset fixed time, the voltage and frequency are restored to the reference value, thereby ensuring the control performance of the microgrid and improving the stability of the system.

Claims

1. A fixed-time dynamic event triggering control method for a microgrid based on an observer, wherein the microgrid is an island microgrid, comprising N DG units and 3 loads, and any one of the N DG units is denoted as DG i , i is the serial number of the DG unit, i = 1, 2, ..., N, N is a positive integer; the DG i It consists of a DC power supply U and an inverter, and the first N-1 DG i The output end is connected to DG through the power line i+1 The output end of DG1 is connected to the output end of DG N-1 The output terminal and DG N The output end of each DG is connected to a load through a power line. i There is a distributed controller installed on the N DG i There is a direct or indirect communication relationship between them through distributed controllers, and any two DGs that have a direct communication relationship i The communication between them is two-way; It is characterized in that The control structure of the distributed controller consists of two parts: primary control and secondary control. The primary control part includes droop control, and the secondary control is a distributed fixed-time dynamic event trigger control based on an observer. The primary control and the secondary control jointly achieve the output voltage and frequency stability of the island microgrid. The specific control steps are as follows: Step 1: Given DG i Output rated voltage E ni and rated frequency ω ni ; DG i The output voltage generated by the primary droop control at the operating time t is recorded as the primary droop output voltage E i (t), DG i The frequency generated by the primary droop control at the operating time t is recorded as the primary droop frequency ω i (t), its expression distribution is: E i (t)=E ni -k qi Q i (t) oh i (t)=ω ni -k pi P i (t) In the formula, Q i (t) is the reactive power output by the distributed generator DGi at the operating time t, P i (t) is the distributed generator DG i The active power output at the operating time t, k qi For DG i Voltage droop control coefficient at operating time t, k pi For DG i The frequency droop control coefficient at the operating time t; Step 2: Start the secondary control and use Artstein transformation to perform delay compensation control to design the distributed fixed-time dynamic event-triggered voltage observer control quantity. and distributed fixed-time dynamic event-triggered frequency observer control Control quantity of distributed fixed-time dynamic event-triggered active power observer Step 3: When the first voltage dynamic event triggering condition is met, the voltage observation value Convergence time of voltage observer control Internal satisfaction E ref is the voltage reference value; when the first frequency dynamic event trigger condition is met, the frequency observation value Convergence time in frequency observation control Internal Satisfaction ω ref is the frequency reference value; when the first active power dynamic event trigger condition is met, the active power observation value Convergence time of active power observation control Internal satisfaction Where j is the serial number of the DG unit, j = 1, 2, ..., N, and i ≠ j. The DG unit corresponding to j is recorded as DG j , k pj For DG j The frequency droop control coefficient at the operating time t; is the observed active power value corresponding to D Gj; The voltage observation control convergence time Frequency Observation Control Convergence Time and active power observation control convergence time The expressions are: In the formula, h ij is the communication delay time, ε is the trigger parameter, ε∈(0,1), α is the first fixed time power index, β is the second fixed time power index, β>1>α>0, is the first voltage weighting parameter of the distributed fixed-time dynamic event trigger observer, is the second voltage weighting parameter of the distributed fixed-time dynamic event trigger observer, is the first voltage observer gain coefficient, is the second voltage observer gain coefficient, is the first voltage observer dynamic event trigger variable gain coefficient, The second voltage observer dynamic event trigger variable gain coefficient, is the voltage observer trigger parameter, is the first weighted undirected graph The Laplacian-like matrix, is the second weighted undirected graph The Laplacian-like matrix, for The second smallest positive eigenvalue of for The second smallest positive eigenvalue of ij Indicates DG i and DG j The communication coupling coefficient between them is i Able to receive DG j , then a ij =1, otherwise, a ij =0; a i0 For DG i The coupling coefficient of the received reference value, a i0 =g i , g i For DG i Positioning gain, if DG i Can obtain system reference voltage information, then g i =1, otherwise g i =0; is the first frequency weighting parameter of the distributed fixed-time dynamic event-triggered observer, is the second frequency weighting parameter of the distributed fixed-time dynamic event trigger observer, is the first frequency observer gain coefficient, is the second frequency observer gain coefficient, is the first frequency observer dynamic event trigger variable gain coefficient, is the dynamic event trigger variable gain coefficient of the second frequency observer, is the frequency observer trigger parameter, is the first active power weighting parameter of the distributed fixed-time dynamic event-triggered observer, is the second active power weighting parameter of the distributed fixed-time dynamic event-triggered observer, is the first active power observer gain coefficient, is the gain coefficient of the second active power observer, is the first active power observer dynamic event trigger variable gain coefficient, is the dynamic event trigger variable gain coefficient of the second active power observer, is the active power observer trigger parameter, Step 4: Design the voltage recovery control variable u triggered by the fixed-time dynamic event based on the observer Ei (t), frequency recovery variable u ωi (t) and active power distribution control variable u Pi (t); Step 5: When the triggering condition of the second voltage dynamic event is met, the secondary control is used to realize the microgrid primary droop voltage E within a limited time T(E). i (t) Tracking voltage observation value When the second frequency dynamic event triggering condition is met, the primary droop frequency ω of the microgrid is realized within a limited time T(ω). i (t) Tracking frequency observation value When the triggering condition of the second active power dynamic event is met, the primary active power of the microgrid is reduced to P within a limited time T(P). i (t) Tracking active power observations The expressions of the voltage recovery control convergence time T(E), the frequency recovery control convergence time T(ω) and the active power distribution control convergence time T(P) are respectively: In the formula, is the observer-based fixed-time dynamic event triggering first voltage weighting parameter, is the observer-based fixed-time dynamic event triggering second voltage weighting parameter, c E1 is the first voltage controller gain, c E2 The second voltage controller gain, c E4 is the first voltage controller dynamic event trigger variable gain coefficient, c E5 is the voltage controller dynamic event trigger variable gain coefficient, c E is the voltage controller trigger parameter, c E ∈(0,1); is the first frequency weighting parameter for the observer-based fixed-time dynamic event trigger, The second frequency weighting parameter is triggered for the observer-based fixed-time dynamic event, cω1 is the first frequency controller gain, c ω2 is the second frequency controller gain, c ω4 is the first frequency controller dynamic event trigger variable gain coefficient, c ω5 Second frequency controller dynamic event trigger variable gain coefficient, c ω is the frequency controller trigger parameter, c ω ∈(0,1); is the observer-based fixed-time dynamic event triggering first active power weighting parameter, is the second active power weighting parameter triggered by the observer-based fixed-time dynamic event, c P1 is the first active power control gain, c P2 is the second active power control gain, c P4 is the first active power distribution controller dynamic event trigger variable gain coefficient, c P5 is the dynamic event trigger variable gain coefficient of the second active power distribution controller, c P is the trigger parameter of the active power distribution controller, c P ∈(0,1); Step 6, turn off secondary control.

2. A time-delay microgrid fixed-time dynamic event triggered observer control method according to claim 1, characterized in that: Step 2: The distributed fixed-time dynamic event triggers the voltage observer to control the variable The expression is: In the formula, For DG i The current voltage dynamic event triggering moment, For DG i The next voltage dynamic event triggers, and k is the triggering time sequence number of the dynamic event, k = 0, 1, 2..., For DG i The output observed voltage at the current voltage dynamic event triggering moment The state value after Artstein transformation, The output voltage of D Gj is observed at The state value after Artstein transformation, For DG i exist The voltage observation value, For DGj The voltage observation value of When i,j∈[1,N],ξ ij (t) is the confidence factor, 0≤ξ ij (t)≤1, tanh() is the hyperbolic tangent function, Triggering hyperbolic tangent function voltage parameters for distributed fixed-time dynamic events, is the third voltage observer gain coefficient; The distributed fixed-time dynamic event-triggered frequency observer controls the variable The expression is: In the formula, For DG i The current frequency dynamic event triggering moment, For DG i The next frequency dynamic event trigger time, and For DG i The output observation frequency is at the current frequency dynamic event triggering moment The state value after Artstein transformation, For DG j The output observation frequency is at the current frequency dynamic event triggering moment The state value after Artstein transformation, in, For DG i At the moment when the current frequency dynamic event is triggered The frequency observation value of For DG j At the moment when the current frequency dynamic event is triggered The frequency observation value of is the confidence factor, Triggering hyperbolic tangent function frequency parameters for distributed fixed-time dynamic events, is the third frequency observer gain coefficient; The distributed fixed-time dynamic event triggers the active power observer to control the variable The control variable expression is: In the formula, For DG i The current active power dynamic event triggering time, For DG i The next active power dynamic event triggering time, and For DG i The output observed active power at the current active power dynamic event triggering moment The state value after Artstein transformation, For DG i The state value of the output observed active power after Artstein transformation at the current active power dynamic event triggering moment, in, For DG i At the current active power dynamic event triggering moment The active power observation value of For DG i At the current active power dynamic event triggering moment The observed value of active power; is the confidence factor, The distributed fixed-time dynamic event triggers the hyperbolic tangent function active power parameter, is the gain coefficient of the third active power observer.

3. A time-delay microgrid fixed-time dynamic event triggered observer control method according to claim 2, characterized in that: Step 3: The first voltage dynamic event triggering condition refers to the event triggering condition of the distributed fixed-time dynamic event triggering voltage observer, and the specific expression is: In the formula, For DG i The voltage observer trigger function y i (t) is the voltage observation value state error, is the voltage observer trigger parameter, ξ i (t) is the measurement error of the distributed fixed-time dynamic event-triggered voltage observer, is the derivative of the internal dynamic event-triggered variable of the distributed fixed-time dynamic event-triggered voltage observer, Γ i (t) is the internal dynamic event trigger variable of the distributed fixed-time dynamic event trigger voltage observer, Trigger variable derivatives for voltage internal dynamic events parameter, When satisfied Condition, event trigger, DG i The control protocol updates the status information, otherwise it is not triggered; A third voltage observer dynamic event trigger variable gain coefficient; The distributed fixed-time dynamic event-triggered voltage observer excludes Zeno behavior, and the dynamic event triggering time interval is: In the formula, The first time interval parameter for the distributed fixed-time voltage dynamic event trigger, The second time interval parameter for the distributed fixed-time voltage dynamic event trigger, The first frequency dynamic event triggering condition refers to the event triggering condition of the distributed fixed-time dynamic event triggering frequency observer, and the specific expression is: In the formula, For DG i The frequency observer trigger function is is the frequency observation state error, is the frequency observer trigger parameter, Measuring error for a distributed fixed-time dynamic event-triggered frequency observer, is the derivative of the internal dynamic event trigger variable of the distributed fixed-time dynamic event trigger frequency observer, is the internal dynamic event trigger variable of the distributed fixed-time dynamic event trigger frequency observer, Trigger derivatives for frequency internal dynamic events parameter, When satisfied Condition, event trigger, DG i The control protocol updates the status information, otherwise it is not triggered; A dynamic event trigger variable gain coefficient for a third frequency observer; The distributed fixed-time dynamic event trigger frequency observer excludes Zeno behavior, and the event trigger time interval is: In the formula, The first time interval parameter for the distributed fixed time frequency dynamic event trigger, The second time interval parameter for distributed fixed time frequency dynamic event triggering, The first active power dynamic event triggering condition refers to the event triggering condition of the distributed fixed-time dynamic event triggering the active power observer: In the formula, For DG i The active power observer trigger function is is the active power observation state error, is the active power observer trigger parameter, The measurement error of the distributed fixed-time dynamic event-triggered active power observer, is the derivative of the internal dynamic event-triggered variable of the distributed fixed-time dynamic event-triggered active power observer, Triggering dynamic event variables inside the active power observer for distributed fixed-time dynamic events; Internal dynamic event trigger for active power parameter, When satisfied Condition, event trigger, DG i The control protocol updates the status information, otherwise it is not triggered; is a dynamic event trigger variable gain coefficient of the third active power observer; The distributed fixed-time dynamic event-triggered active power observer excludes Zeno behavior, and the event triggering time interval is: In the formula, The first time interval parameter for the distributed fixed-time active power dynamic event triggering, The second time interval parameter for the distributed fixed-time active power dynamic event triggering, 4. A time-delay microgrid fixed-time dynamic event triggered observer control method according to claim 3, characterized in that: The voltage recovery control variable u triggered by the fixed-time dynamic event based on the observer in step 4 is Ei The expression of (t) is as follows: In the formula, For DG i The current voltage dynamic event triggering moment, For DG i The next voltage dynamic event triggers, and e Ei (t) is the voltage observation value of the distributed generator DGi in the isolated microgrid at time t and output voltage E i (t) The state error between The voltage parameter of the hyperbolic tangent function is triggered by the fixed-time dynamic event based on the observer, c E3 is the third voltage controller gain; The frequency recovery control variable u is triggered by the fixed-time dynamic event based on the observer. ωi The expression of (t) is: In the formula, For DG i The current frequency dynamic event triggering moment, For DG i The next frequency dynamic event trigger time, and e ωi (t) is the DG in the isolated microgrid at time t i The frequency observation value of and output frequency ω i (t) The state error between The frequency parameter of the hyperbolic tangent function is triggered for the fixed-time dynamic event based on the observer, c ω3 is the third frequency controller gain; The active power distribution control variable u triggered by the fixed-time dynamic event based on the observer Pi The expression of (t) is: In the formula, For DG i The current active power dynamic event triggering time, For DG i The next active power dynamic event triggering time, and e Pi (t) is the DG in the isolated microgrid at time t i The active power observation value And the output active power P i (t) The state error between is the active power parameter of the hyperbolic tangent function triggered by the fixed-time dynamic event based on the observer, c P3 is the third active power control gain.

5. A time-delay microgrid fixed-time dynamic event triggered observer control method according to claim 4, characterized in that: Step 5: The second voltage dynamic event triggering condition refers to the event triggering condition of the voltage controller triggered by the fixed-time dynamic event based on the observer, and the specific expression is: In the formula, Φ Ei (t) is DG i The voltage controller trigger function, Φ Ei (t) = θ E (|ξ Ei (t)|-c E c E1 |e Ei (t)| α -c E c E2 |e Ei (t)| β -c E c E3 ) is, θ E is the voltage controller trigger parameter, θ E >0,ξ Ei (t) is the voltage measurement error triggered by a fixed-time dynamic event based on the observer, is the derivative of the internal dynamic event trigger variable based on the fixed-time observer dynamic event trigger, Γ Ei (t) is the internal dynamic event trigger variable based on the fixed-time dynamic event trigger of the observer, γ E Trigger for voltage internal dynamic events Parameter, γ E ∈(0,1), when Φ Ei (t)≥Γ E When the i(t) condition is met, the event is triggered, DG i The control protocol updates the status information, otherwise it will not be triggered; c E6 a variable gain coefficient for a third voltage controller dynamic event trigger; The observer-based fixed-time dynamic event-triggered voltage controller excludes Zeno behavior, and the event triggering time interval is: In the formula, ρ E1 (0) is the first time interval parameter for triggering a voltage dynamic event based on a fixed time observer, ρ E2 (0) is the second time interval parameter triggered by the fixed-time voltage dynamic event based on the observer, The second frequency dynamic event triggering condition refers to the event triggering condition of the frequency controller triggered by a fixed-time dynamic event based on an observer, and the specific expression is: In the formula, φ ωi (t) is DG i The frequency controller trigger function, φ ωi (t) = θ ω (|ξ ωi (t)|-c ω c ω1 |e ωi (t)| α -c ω c ω2 |e ωi (t)| β -c ω c ω3 ), θ ω is the frequency controller trigger parameter, θ ω >0,ξ ωi (t) is the error of the fixed-time dynamic event-triggered frequency controller based on the observer, is the derivative of the internal dynamic event trigger variable based on the fixed-time observer dynamic event trigger, Γ ωi (t) is the internal dynamic event trigger variable based on the fixed-time dynamic event trigger of the observer, , γ ω Triggering derivatives for internal dynamic events Parameter, γ ω ∈(0,1), when Φ ωi (t)≥Γ ωi (t) condition, event trigger, DG i The control protocol updates the status information, otherwise it will not be triggered; c ω6 The third frequency controller dynamic event trigger variable gain coefficient; The observer-based fixed-time dynamic event-triggered frequency controller excludes Zeno behavior, and the event-triggered time interval is: In the formula, ρ ω1 (0) is the first time interval parameter for triggering a dynamic event based on a fixed time frequency observer, ρ ω2 (0) is the second time interval parameter for triggering a dynamic event based on a fixed time frequency observer, The second active power dynamic event triggering condition refers to an event triggering condition for triggering an active power controller based on a fixed-time dynamic event of an observer, and the specific expression is: In the formula, Φ Pi (t) is DG i The trigger function of the active power distribution controller Φ Pi (t) = θ P (|ξ Pi (t)|-c P c P1 |e Pi (t)| α -c P c P2 |e Pi (t)| β -c P c P3 ), θ P is the trigger parameter of active power distribution controller, θ P >0,ξ Pi (t) is the active power measurement error triggered by the fixed-time dynamic event based on the observer, is the derivative of the internal dynamic event trigger variable of the observer-based fixed-time dynamic event trigger active power, Γ Pi (t) is the internal dynamic event trigger variable of active power triggered by fixed-time dynamic events based on observer, γ P Trigger variable derivative for active power internal dynamic events Parameter, γ P ∈(0,1), when φ Pi (t)≥Γ Pi (t) condition, event trigger, DG i The control protocol updates the status information, otherwise it will not be triggered; c P6 A dynamic event trigger variable gain coefficient for the third active power distribution controller; The observer-based fixed-time dynamic event-triggered active power distribution controller excludes Zeno behavior, and the event triggering time interval is: In the formula, ρ P1 (0) is the first time interval parameter for triggering the active power dynamic event based on the fixed time observer, ρ P2 (0) is the second time interval parameter triggered by the fixed-time active power dynamic event based on the observer,

Images