Micro-grid group emergency cooperative control method and system

Abstract

The application provides a micro-grid group emergency cooperative control method and system, and relates to the field of micro-grid group operation control. The micro-grid group emergency cooperative control method firstly establishes a system steady-state convergence formula according to a cooperative control target; combines local known information, estimates average values of each state quantity and calculates neighbor node interaction information based on a dynamic convergence algorithm, establishes group-to-group and group-to-group distributed cooperative control, fault splitting, compensation quantity satisfying mobile energy storage active power sharing and SOC balance is obtained based on the dynamic convergence algorithm and a linear quadratic regulator; an event triggering condition is constructed through an imbalance of the estimated average value and information transmission error; mobile energy storage seamless exit after fault recovery is realized through supply and demand power transfer. The method can realize micro-grid group frequency / key bus voltage recovery, power sharing and mobile energy storage SOC balance, has the advantages of convergence performance and communication cost, and improves flexibility and elasticity of the micro-grid group under fault conditions.

Description

Technical Field

[0001] This invention relates to the field of microgrid group operation and control technology, specifically to a microgrid group emergency collaborative control method and system. Background Technology

[0002] Microgrid clusters, as integrated networks composed of multiple interconnected microgrids, have become a major way to increase the penetration rate of distributed generation (DG), improve power supply reliability, and enhance grid resilience. When large load switching or DG failures occur, to address the power imbalance between supply and demand in the microgrid cluster, it is necessary to dynamically change the system topology and implement emergency control to provide frequency and voltage support, ensuring maximum continuous power supply to critical loads. However, limited by controllable DG capacity and the volatility of renewable energy sources, microgrid clusters with islanded characteristics may not be sufficient to meet continuous power supply demands. Therefore, it is necessary to allocate a certain number of mobile emergency power sources within the system to proactively improve spatial flexibility and survivability.

[0003] Mobile energy storage systems (MESS) are used to connect to distributed generation systems (DGs) during emergency power outages via mobile energy storage vehicles. Their advantages, such as high mobility, fast response, and low operating costs, have led to their application in emergency control. Coordinated control between MESS and DG is crucial for flexible system regulation. Traditional centralized control requires robust communication and computing capabilities and suffers from "single point of failure," limiting its application. Distributed control, with its high reliability and flexibility, is more suitable for cluster coordinated control. Average consensus algorithms are commonly used to achieve coordinated control of microgrid clusters. However, average consensus algorithms based on the Laplace matrix of the communication graph achieve global average consensus asymptotically during iteration. Their control effectiveness largely depends on the system's communication topology and the synchronization and accurate acquisition of interactive information. Furthermore, considering the frequent switching of MESSs in emergency power supply control scenarios, the constantly changing system topology and communication network, and the temporary communication links between DGs and connected MESSs in poor communication environments, conventional consensus algorithms face numerous difficulties and challenges in implementing emergency control of microgrid clusters. Therefore, it is necessary to study a distributed cooperative control strategy for microgrid groups that balances convergence performance and communication costs, so as to improve the stability and flexibility of the system under fault conditions. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a microgrid group emergency collaborative control method and system to solve the problems mentioned in the background section.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] On the one hand, a method for emergency coordinated control of microgrid groups is provided, including:

[0009] Based on the system steady-state convergence formula and the average value estimation model of active power and reactive power, an active power and reactive power sharing controller is established to obtain the active power and reactive power sharing control compensation quantities.

[0010] In the fault-free operation, mobile energy storage provides frequency and voltage support through pre-synchronized emergency access. The compensation amount that meets the requirements of active power distribution and state of charge balance of mobile energy storage is obtained through the average value estimation model of active power and reactive power and the linear quadratic regulator.

[0011] The event triggering conditions are constructed by the imbalance of the estimated average value and the information transmission error.

[0012] Fault recovery enables seamless decommissioning of mobile energy storage through power transfer between supply and demand.

[0013] The system achieves its various control objectives by controlling the compensation amount based on the equal distribution of active and reactive power, as well as the compensation amount that satisfies the equal distribution of active power and the balance of state of charge in mobile energy storage.

[0014] Preferably, the system steady-state convergence equation includes steady-state convergence equations for active and reactive power between microgrids and steady-state convergence equations for active and reactive power within each microgrid.

[0015] The steady-state convergence equations for active and reactive power between microgrids include:

[0016] Based on the coordinated control objective of power sharing by capacity among interconnected microgrids, the following equation is established:

[0017]

[0018]

[0019] In the formula, ε XY ε represents the state of the interconnection switch between interconnected microgrids X and Y. XY =0 indicates a closed loop, ε XY =1 indicates disconnection; m X,i (m Y,j ) and n X,i (n Y,j ) represent the active and reactive droop coefficients of the i-th (j)-th distributed power source in microgrid X(Y), respectively; and Let X and Y represent the average active and reactive power outputs of microgrid X(Y) at time t, respectively; the steady-state convergence equations for active and reactive power within each microgrid include:

[0020] Based on the coordinated control objective of distributing active and reactive power output according to capacity among distributed power sources in each microgrid, the following equation is established:

[0021]

[0022]

[0023] Among them, P X,i (t) and P X,j (t) represents the active power of the i-th and j-th distributed generation in microgrid X at time t, respectively; Q X,i (t) and Q X,j (t) represent the reactive power of the i-th and j-th distributed power sources in microgrid X at time t, respectively; preferably, the establishment of the active power and reactive power average estimation model includes:

[0024] For distributed power sources within each microgrid, the active and reactive power values ​​are calculated by sampling the output voltage and current at the current moment. These values ​​are then combined with the average information of the state variables of other nodes already obtained locally, and the intermediate temporary variable representing the equal distribution of active and reactive power is calculated using the following formula.

[0025]

[0026]

[0027] Where k represents the number of iterations; γ X,i =m X,i P X,i and η X,i =n X,i Q X,i Let w represent the product of the active power and reactive power of the i-th distributed power source in microgrid X and its droop coefficient, respectively; γX,i (w ηX,i ) represents the weighting information of the active (reactive) power of the i-th distributed power source in the average value estimation; s γj→i (s ηj→i x is the weight value passed from distributed source j to neighbor node i, but does not contain information on the distribution of active (reactive) power of node i; γj→i (x ηj→i N represents the weighted average of state variables transmitted from distributed source j to neighbor node i, but without including the active (reactive) power of node i; i Let i be the set of neighboring nodes of node i;

[0028] Using the obtained intermediate temporary variables, substitute them into the following formula to dynamically estimate the average value of active power and reactive power:

[0029]

[0030]

[0031] in, and Let represent the average values ​​of active power and reactive power state variables obtained by the local estimation of the i-th distributed power source in microgrid X, respectively;

[0032] Calculate the information that distributed power source i needs to pass to each neighbor node at the next moment.

[0033] Preferably, the establishment of the active and reactive power sharing controller to obtain the active and reactive power sharing control compensation amount specifically includes:

[0034] The active and reactive power sharing control compensation includes active and reactive power sharing controllers between interconnected microgrids and active and reactive power sharing controllers within each microgrid.

[0035] Establishment of the active and reactive power sharing controller between the interconnected microgrids:

[0036]

[0037] Among them, Ω PXY,i and Φ QXY,i The compensation amount is shared equally between active and reactive power in interconnected microgrids; k PXY,i and k QXY,i The integral coefficient;

[0038] The establishment of the active and reactive power sharing controllers in each microgrid:

[0039]

[0040] Among them, Ω PX,i and Φ QX,i k represents the compensation amount for the active and reactive power of distributed power sources within the microgrid X. PX,i and k QX,i is the integral coefficient.

[0041] Preferably, in the fault routing, the mobile energy storage provides frequency and voltage support through pre-synchronized emergency access. The compensation amount, which satisfies the active power distribution and state-of-charge balance of the mobile energy storage, is obtained through an active power and reactive power average estimation model and a linear quadratic regulator. Specifically, this includes:

[0042] After the system fault is resolved, the mobile energy storage is smoothly integrated into the faulted microgrid by adjusting the voltage phase angle and amplitude on both sides of the synchronization access point.

[0043]

[0044] Where, β r,m β represents the operating state of the m-th mobile energy storage unit in the faulty microgrid r. r,m =1, indicating that mobile energy storage needs to be connected to the system, β r,m =0 indicates that it has been connected to the system; Ω θr,m and Φ Er,m This is a pre-synchronization compensation item; The phase angle difference of the voltages on both sides of the connection point; The voltage phase angle difference and amplitude difference on both sides of the access point; k θr,m and k Er,m The integral coefficient;

[0045] The actual output angular frequency ω of each DG and mobile energy storage in the faulty microgrid is calculated using the following formula. r,i Restored to the system's rated angular frequency ω * Meanwhile, the key bus voltage V rc Restore to rated value

[0046]

[0047] Ω ωr,i and Φ vr,i For frequency / critical bus voltage recovery compensation; k ωr,i and k vr,i g is the integral coefficient; r,i Does the meter power supply i receive critical bus voltage rating information? If g r,i =1, receive the information; otherwise, do not receive. Within a faulty microgrid, there is one and only one power source capable of receiving this information.

[0048] Mobile energy storage m connected to the faulty microgrid r is taken as a neighbor node of the distributed power source i. The average power of each power source and the average state of charge (SOC) of each mobile energy storage are estimated using an active power and reactive power average estimation model. Establish a mobile energy storage active power sharing-SOC balancing collaborative controller according to the following formula:

[0049]

[0050] Among them, Ω Sr,m For mobile energy storage, m represents the active power-SOC collaborative compensation amount; k Sr1,m and k Sr2,mThese are the integral coefficients for controlling active power distribution and SOC balancing in mobile energy storage, respectively; ρ r,m The SOC value of the mobile energy storage m within the faulty microgrid r; preferably, the k Sr1,m and the k Sr2,m The optimized design is as follows:

[0051] Establish a state-space model for mobile energy storage

[0052] Based on this state-space model, the following algebraic Riccati equation is constructed:

[0053] C T R r +R r C+AR r DB -1 D T R r =0

[0054] Where A and B are positive definite matrices; C and D are mobile energy storage state matrices;

[0055] Solving the equation yields a unique positive definite solution R. r The optimized control parameter K is obtained from the following formula. r =[k Sr1,m ,k Sr2,m ] T :

[0056] K r =B -1 D T R r .

[0057] Preferably, the construction of event triggering conditions based on the estimated average imbalance and information transmission error specifically includes:

[0058] Calculate the error e in the transmission of weight information in the dynamic convergence algorithm. s,i→j Error e of state quantity information x,i→j :

[0059]

[0060] in, Determine the necessary triggering times for the built-in event detection module;

[0061] Calculate the imbalance μ of the average value of the state variables estimated by the dynamic convergence algorithm. Constructed event triggering conditions:

[0062]

[0063] Where, ζi→j =[e x,i→j ,e s,i→j ] T Ξ=diag(φ1,φ2) is the coefficient matrix, σ i This is the trigger threshold parameter.

[0064] Preferably, the fault recovery achieves seamless decommissioning of mobile energy storage through power transfer between supply and demand, specifically including:

[0065] For the distributed power source i within the faulty microgrid r, the power transfer controller is established as follows:

[0066]

[0067] For mobile energy storage m within a faulty microgrid r, assuming a total of M storage devices are connected, the power transfer controller is established as follows:

[0068]

[0069] Where, α r,m =1 indicates that the mobile energy storage needs to be removed from the system, k Δpr,i k Δqr,i k Δpr,m k Δqr,m Let ΔP be the integral coefficient. r,m and ΔQ r,m The active and reactive power outputs before the mobile energy storage is decommissioned.

[0070] Preferably, the system's various control objectives are achieved by controlling the compensation amount based on the equal distribution of active and reactive power, the frequency and voltage recovery compensation amount, and the compensation amount that satisfies the equal distribution of active power and the state of charge balance of mobile energy storage. Specifically, this includes:

[0071] The total compensation amount Ω is obtained by summing up the compensation amounts of the distributed power sources. X(r),i and Φ X(r),i The total compensation amount Ω is obtained by summing the compensation amounts of various mobile energy storage systems. r,m and Φ r,m These are then added to their respective droop control equations to collaboratively achieve the system's various control objectives:

[0072]

[0073]

[0074] On the other hand, a microgrid group emergency collaborative control system is provided, including:

[0075] The first preprocessing module is used to establish an active power and reactive power sharing controller based on the system steady-state convergence formula and the average value estimation model of active power and reactive power, and to obtain the active power and reactive power sharing control compensation amount.

[0076] The second preprocessing module, fault routing, provides frequency and / or voltage support for mobile energy storage through pre-synchronized emergency access. It obtains the compensation amount that meets the requirements of active power distribution and state of charge balance of mobile energy storage through the average value estimation model of active power and reactive power and the linear quadratic regulator.

[0077] The processing module is used to construct event triggering conditions based on the estimated average imbalance and information transmission error; and is used for fault recovery, enabling seamless withdrawal of mobile energy storage through power transfer between supply and demand.

[0078] The control module achieves various control objectives of the system by controlling the compensation amount based on the equal distribution of active and reactive power, as well as the compensation amount that satisfies the equal distribution of active power and the balance of state of charge of mobile energy storage.

[0079] (III) Beneficial Effects

[0080] The microgrid emergency collaborative control method and system designed in this invention are based on a dynamic convergence algorithm. Under the condition of eliminating redundant data, the state variables of each node can converge to the estimated average value in a finite number of iterations. Simultaneously, it achieves multiple control objectives, including system frequency / critical bus voltage recovery, power equilibration, and mobile energy storage SOC balancing. Compared with conventional consensus algorithms, it improves control convergence speed and stability, has higher fault tolerance, and enhances the flexibility and resilience of the microgrid under fault conditions. This invention further introduces an event triggering mechanism to reduce the communication cost and pressure of the distributed controller, which is more conducive to the stable operation of faulty microgrids temporarily built with communication networks. This invention also proposes a seamless access / exit method for mobile energy storage based on pre-synchronization and power transfer, reducing the transient impact problems easily caused by emergency power supply access / exit from the system and avoiding further expansion or secondary occurrence of faults. Attached Figure Description

[0081] Figure 1 This is a flowchart of the control method of the present invention;

[0082] Figure 2 This is the microgrid group simulation system used in the embodiments of the present invention;

[0083] Figure 3 This is a waveform diagram of the active power output of each distributed power source and mobile energy storage in the microgrid group in an embodiment of the present invention.

[0084] Figure 4This is a waveform diagram of the reactive power output of each distributed power source and mobile energy storage in the microgrid group in this embodiment of the invention;

[0085] Figure 5 This is a waveform diagram of the output frequency of each distributed power source and mobile energy storage in the microgrid group in an embodiment of the present invention;

[0086] Figure 6 This is a waveform diagram of the key bus voltage of the microgrid group and the faulty microgrid in the embodiment of the present invention;

[0087] Figure 7 These are waveform diagrams of the charge state of each mobile energy storage device connected to the faulty microgrid in this embodiment of the invention.

[0088] Figure 8 This is a waveform diagram of the communication trigger interval of the active power sharing controller for each power source in the microgrid group in an embodiment of the present invention;

[0089] Figure 9 This is a waveform diagram of the communication trigger interval of the reactive power sharing controller for each power source in the microgrid group in an embodiment of the present invention;

[0090] Figure 10 This is a waveform diagram of the active power output of each distributed power source and mobile energy storage in a microgrid group when a cooperative control strategy based on a conventional consensus algorithm is adopted in an embodiment of the present invention.

[0091] Figure 11 This is a waveform diagram of the charge state of each mobile energy storage device connected to a faulty microgrid when a collaborative control strategy based on a conventional consensus algorithm is adopted in an embodiment of the present invention. Detailed Implementation

[0092] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0093] Example

[0094] like Figure 1 As shown, this invention designs an emergency collaborative control method for microgrid groups, comprising:

[0095] Based on the system steady-state convergence formula and the average value estimation model of active power and reactive power, an active power and reactive power sharing controller is established to obtain the active power and reactive power sharing control compensation quantities.

[0096] In the fault-free operation, mobile energy storage provides frequency and / or voltage support through pre-synchronized emergency access. The compensation amount that meets the requirements of active power distribution and state of charge balance of mobile energy storage is obtained through the average value estimation model of active power and reactive power and the linear quadratic regulator.

[0097] The event triggering conditions are constructed by the imbalance of the estimated average value and the information transmission error.

[0098] Fault recovery enables seamless decommissioning of mobile energy storage through power transfer between supply and demand.

[0099] The system achieves its various control objectives by controlling the compensation amounts for the equal distribution of active and reactive power, as well as the compensation amounts that satisfy the equal distribution of active power and the state of charge balance of mobile energy storage.

[0100] In practical applications, the specific steps include the following:

[0101] Step A: Based on the microgrid group collaborative control objective, establish the corresponding system steady-state convergence equation, and combine all the information already obtained locally, apply the dynamic convergence algorithm to estimate the average value of each state variable, and simultaneously calculate the interaction information between neighbors at the next time step to establish inter-group and intra-group distributed collaborative control, and then proceed to Step B;

[0102] Step B: After the system fault is resolved, the mobile energy storage is pre-synchronized by voltage amplitude / phase angle and then connected to the faulty microgrid to provide frequency / voltage support. The compensation amount for power sharing between power sources and SOC balance between mobile energy storage is obtained through dynamic convergence algorithm and linear quadratic regulator, and then proceeds to step C.

[0103] Step C: Construct event triggering conditions based on the imbalance of the transmitted weight information, state quantity information error, and estimated average state quantity value of the dynamic convergence algorithm, thereby reducing the communication cost and pressure of the controller, and then proceed to step D;

[0104] Step D: After the fault is recovered, the mobile energy storage devices are seamlessly decommissioned through power transfer between supply and demand.

[0105] In step A above, the inter-group-intra-group power sharing control compensation amount is calculated from steps A01 to A04 as follows:

[0106] Step A01: Establish the steady-state convergence formula for microgrid group-level power allocation based on the goal of equal power distribution among microgrids and coordinated control:

[0107]

[0108]

[0109] In the formula, ε XYε represents the state of the interconnection switch between interconnected microgrids X and Y. XY =0 indicates a closed loop, ε XY =1 indicates disconnection; m X,i (m Y,j ) and n X,i (n Y,j ) represent the active and reactive droop coefficients of the i-th (j)-th distributed power source in microgrid X(Y), respectively; and Let X(Y) represent the average active and reactive power outputs of the microgrid at time t, respectively; then, based on the power sharing and collaborative control objective within the microgrid, establish the steady-state convergence equation for the microgrid-level power distribution:

[0110]

[0111]

[0112] Among them, P X,i (t) and P X,j (t) represents the active power of the i-th and j-th distributed generation in microgrid X at time t, respectively; Q X,i (t) and Q X,j (t) represents the reactive power of the i-th and j-th distributed power sources in microgrid X at time t, respectively.

[0113] Step A02: Sample the current output voltage and current of distributed power sources in each microgrid, calculate the active and reactive power values, combine them with the average information of the state variables of other nodes already obtained locally, and use the following formula to calculate the intermediate temporary variable representing the equal distribution of active (reactive) power.

[0114]

[0115]

[0116] Where k represents the number of iterations; γ X,i =m X,i P X,i and η X,i =n X,i Q X,i Let w represent the product of the active power and reactive power of the i-th distributed power source in microgrid X and its droop coefficient, respectively; γX,i (w ηX,i ) represents the weighting information of the active (reactive) power of the i-th distributed power source in the average value estimation; s γj→i (s ηj→i x is the weight value passed from distributed source j to neighbor node i, but does not contain information on the distribution of active (reactive) power of node i;γj→i (x ηj→i N represents the weighted average of state variables transmitted from distributed source j to neighbor node i, but without including the active (reactive) power of node i; i Let i be the set of neighboring nodes of node i;

[0117] Then, substituting the results from equations (5) and (6) into the following equation, we can estimate the average active power of the i-th distributed power source in the microgrid X. and average reactive power

[0118]

[0119]

[0120] Step A03: Calculate the information that distributed power source i needs to interact with each neighbor node at the next moment, so as to provide a basis for dynamically estimating the new weighted average value of each state variable based on step A02 in the next step;

[0121] Step A04: Next, combine the active and reactive power average estimation methods from steps A02 and A03 with equations (1) to (2) to obtain the active and reactive power sharing controller between interconnected microgrids:

[0122]

[0123] Among them, Ω PXY,i and Φ QXY,i The compensation amount is shared equally between active and reactive power in interconnected microgrids; k PXY,i and k QXY,i is the integral coefficient.

[0124] Similarly, by combining the methods for estimating the average active and reactive power in steps A02 and A03 with equations (3) to (4), the active and reactive power sharing controllers in each microgrid are obtained:

[0125]

[0126] Among them, Ω PX,i and Φ QX,i k represents the compensation amount for the active and reactive power of distributed power sources within the microgrid X. PX,i and k QX,i is the integral coefficient.

[0127] In step B above, the mobile energy storage collaborative control compensation amount for the emergency access failure system is calculated from steps B01 to B03:

[0128] Step B01: Following the formula, the phase angle and amplitude of the voltages on both sides of the synchronization access point are used to smoothly integrate mobile energy storage into the fault-prone microgrid after system fault separation.

[0129]

[0130] Where, β r,m β represents the operating state of the m-th mobile energy storage unit in the faulty microgrid r. r,m =1, indicating that mobile energy storage needs to be connected to the system, β r,m =0 indicates that it has been connected to the system; Ω θr,m and Φ Er,m This is a pre-synchronization compensation item; The phase angle difference of the voltages on both sides of the connection point; The voltage phase angle difference and amplitude difference on both sides of the access point; k θr,m and k Er,m is the integral coefficient.

[0131] Step B02: Calculate the actual output angular frequency ω of each DG and mobile energy storage unit in the faulty microgrid using the following formula. r,i Restored to the system's rated angular frequency ω * At the same time, the key bus voltage V rc Restored to rated value V c * :

[0132]

[0133] Among them, Ω ωr,i and Φ vr,i For frequency / critical bus voltage recovery compensation; k ωr,i and k vr,i g is the integral coefficient; r,i Does the meter power supply i receive critical bus voltage rating information? If g r,i =1, receive the information; otherwise, do not receive it. There is one and only one power source in the faulty microgrid that can receive the information.

[0134] Step B03: Take the mobile energy storage m connected to the faulty microgrid r as a neighbor node of the distributed power source i, and use steps A02 and A03 to estimate the average power of each power source and the average state of charge (SOC) value of each mobile energy storage. Establish a mobile energy storage active power sharing-SOC balancing collaborative controller:

[0135]

[0136] Among them, Ω Sr,m For mobile energy storage, m represents the active power-SOC collaborative compensation amount; k Sr1,m and k Sr2,mThese are the integral coefficients for controlling active power distribution and SOC balancing in mobile energy storage, respectively; ρ r,m Let m be the SOC value of the mobile energy storage unit m within the faulty microgrid r. Then, design a reasonable parameter k for equation (13). Sr1,m k Sr2,m To improve the dynamic performance of collaborative active power sharing and SOC balancing, the specific steps are as follows:

[0137] First, establish a state-space model for mobile energy storage;

[0138] Secondly, based on this state-space model, the following formal algebraic Riccati equation is constructed:

[0139] C T R r +R r C+AR r DB -1 D T R r =0 Equation (14)

[0140] Where A and B are positive definite matrices; C and D are mobile energy storage state matrices.

[0141] Finally, the unique positive definite solution R of the algebraic Riccati equation is obtained. r The optimized control parameter K is obtained from the following formula. r =[k Sr1,m ,k Sr2,m ] T :

[0142] K r =B -1 D T R r Equation (15)

[0143] In step C above, event triggering conditions are constructed from steps C01 to C02 to reduce controller communication costs and pressure:

[0144] Step C01: Calculate the error e in the transmission of weight information in the dynamic convergence algorithm. s,i→j Error e of state quantity information x, i →j :

[0145]

[0146] in, Determine the necessary trigger times for the built-in event detection module.

[0147] Step C02: Next, calculate the imbalance μ of the average value of the state variables estimated by the dynamic convergence algorithm. This leads to the event triggering conditions:

[0148]

[0149] Where, ζ i→j =[e x,i→j ,e s,i→j ] T Ξ=diag(φ1,φ2) is the coefficient matrix, σ i This is the trigger threshold parameter.

[0150] In step D above, the power transfer amounts for each power source are obtained through the following steps, enabling seamless withdrawal of mobile energy storage after fault recovery:

[0151] The output of mobile energy storage that needs to be decommissioned is reduced, and then the remaining distributed power sources in the system take over this portion of the output in advance, completing a seamless transfer of power supply and demand. For the distributed power source i within the faulty microgrid r, the power transfer controller is established as follows:

[0152]

[0153] For the mobile energy storage m (assuming a total of M storage units are connected) within the faulty microgrid r, the power transfer controller is established as follows:

[0154]

[0155] Where, α r,m =1 indicates that the mobile energy storage needs to be removed from the system, k Δpr,i k Δqr,i k Δpr,m k Δqr,m Let ΔP be the integral coefficient. r,m and ΔQ r,m The active and reactive power outputs before the mobile energy storage is decommissioned.

[0156] Finally, by superimposing equations (9), (10), (12), and (18), the total compensation amount Ω of the distributed power source i is obtained. X(r),i and Φ X(r),i :

[0157]

[0158] Superimposing equations (10) to (13) and (19) yields the total compensation amount Ω for mobile energy storage m. r,m and Φ r,m :

[0159]

[0160] By adding equations (20) and (21) to their respective droop control equations, the various control objectives of the system can be achieved in a coordinated manner.

[0161] Applying the above-designed technical solution to practice, the simulation system is as follows: Figure 2 As shown, three microgrids constitute a microgrid cluster, where DG1-4 represent four controllable distributed generation sources, and MESS1-3 represent three configured mobile energy storage units. Each DG in the microgrid cluster is connected to a common voltage bus through different output impedances, and each distributed generation source and mobile energy storage unit has the same active and reactive power capacity. During normal operation, the interconnection switches between the microgrids are closed, and the entire cluster operates interconnectedly, jointly supplying power to seven loads in the system. The initial SOCs of MESS1-MESS3 are 77%, 73%, and 69%, respectively. Based on the microgrid cluster emergency collaborative control method based on a dynamic convergence algorithm according to an embodiment of the present invention, a system controller is established, and a microgrid cluster model including mobile energy storage is built based on the MATLAB / Simulink simulation platform to verify the control effect of the method of the present invention.

[0162] Corresponding to Figure 2 The simulation conditions are as follows: 1) The system operates normally from 0 to 1 second; 2) At 1 second, DG2 fails and exits. After 10ms, the system detects the fault. To ensure power supply to as many loads as possible, the system is split into 3 sub-microgrids. At the same time, loads 2 and 4 in microgrid 2 are disconnected according to their importance, and each mobile energy storage vehicle goes to the designated access point according to its access priority; 3) At 4 seconds, MESS1 arrives at the designated access point and coordinates with DG3 to form a network for power supply. After the voltage / frequency stabilizes, the more important load 4 is reconnected after 5 seconds; 4) At 7 seconds, MESS2 and MESS3 form a network for power supply, start SOC balancing control, and reconnect the less important load 2; 5) At 14 seconds, DG2 recovers from the fault and reconnects to microgrid 2; 6) The system operates stably for 17 seconds, and each microgrid is reconnected and put into operation; 7) At 20 seconds, the power supply and demand of each MESS are seamlessly transferred to each DG, presenting a "pseudo-exit" state, and exits the system at 22 seconds. Figures 3 to 9 The figure shows the simulation results of microgrid group control in this embodiment. Figure 3 This is a waveform diagram of the active power output of each distributed power source and mobile energy storage in a microgrid group. The horizontal axis represents time in seconds, and the vertical axis represents active power in kilowatts. Figure 4 The graph shows the reactive power output of each distributed power source and mobile energy storage in the microgrid group. The horizontal axis represents time in seconds, and the vertical axis represents active power in kilovars. Figure 5 This is a waveform diagram showing the output frequency of each distributed power source and mobile energy storage in a microgrid group. The horizontal axis represents time in seconds, and the vertical axis represents frequency in Hertz. Figure 6 This is a waveform diagram of the voltage of the key bus in a microgrid cluster and a faulty microgrid. The horizontal axis represents time in seconds, and the vertical axis represents voltage in pu. Figure 7The waveforms of the state of charge (SOC) of various mobile energy storage devices connected to the faulty microgrid are shown. The horizontal axis represents time (in seconds), and the vertical axis represents the SOC (in percentile). Figures 3 to 6 It can be seen that initially, the active and reactive power of each DG in the microgrid group is precisely evenly distributed, and the frequency / voltage is stable at the rated value. At the moment of DG2 failure, the system communication network changes accordingly, resulting in a power imbalance between supply and demand, causing significant frequency and voltage surges. Stable operation only resumes after disconnection and load shedding operations. After emergency connection of each MESS to the system at 4 and 7 seconds, each power source quickly outputs power evenly according to its capacity, and after load is applied, each power source quickly adjusts and re-achieves power distribution control. Because amplitude and phase angle were pre-synchronized before each MESS connection, from... Figure 5 and Figure 6 It is evident that the frequency / voltage surge generated by MESS at the moment of connection is relatively small. For example... Figure 7 As shown, SOC balancing control starts after all MESSs are connected, working in conjunction with the active power sharing controller to achieve control effects, and all MESSs reach SOC balance in about 13 seconds. At 14 and 17 seconds, DG2 fault recovery and the merging of each disconnected microgrid occur, and all DGs in the system work together with the MESSs to output power, reaching a new steady state. Figures 3 to 6 At 20 seconds, the power of each MESS is seamlessly transferred, resulting in only slight frequency and voltage fluctuations. At 22 seconds, when each MESS exits the system, the impact on the system is almost zero, achieving a smooth exit. Figure 8 This is a waveform diagram of the communication trigger interval of the active power sharing controller for each power source in a microgrid group. The horizontal axis represents time in seconds, and the vertical axis represents the trigger pulse in pu. Figure 8 This is a waveform diagram showing the communication trigger interval between power sources in a microgrid group without a power sharing controller. The horizontal axis represents time (seconds), and the vertical axis represents the trigger pulse (pu). Figure 8 and Figure 9 As shown, for the coordinated control process of distributed power sources and mobile energy storage in a faulty microgrid, compared with the traditional periodic triggering, the communication interval of the controller is significantly increased when the event triggering mechanism is adopted, and the communication interaction behavior is no longer transmitted at equal intervals. Correspondingly, the total data transmission volume will also be reduced, which significantly reduces the controller communication cost.

[0163] Figure 10 The waveforms of active power output from each distributed power source and mobile energy storage in a microgrid cluster when a collaborative control strategy based on a conventional consensus algorithm is adopted are shown. The horizontal axis represents time in seconds, and the vertical axis represents active power in kilowatts. Figure 11The graphs show the state-of-charge (SOC) waveforms of various mobile energy storage devices connected to a faulty microgrid when a cooperative control strategy based on a conventional consensus algorithm is adopted. The horizontal axis represents time (seconds), and the vertical axis represents the SOC (percentage of charge). Figure 10 and Figure 11 and Figure 3 and Figure 7 In comparison, it can be seen that when using the conventional consensus algorithm, each MESS finally achieves SOC balance in about 19.5 seconds, and the active power of DG3 and each MESS is accurately evenly distributed. The convergence time is nearly 6.5 seconds slower than the method proposed in this invention. Therefore, the superiority of the proposed method in terms of convergence speed is verified.

[0164] This invention proposes an emergency collaborative control method for microgrid clusters that considers mobile energy storage balancing. By establishing a cooperative control steady-state expression and combining it with a dynamic convergence algorithm to estimate the average state variables, a distributed emergency collaborative controller for microgrid clusters that balances convergence speed and stability is established. Furthermore, an event-triggered mechanism is introduced to reduce communication and control costs. Addressing the shortcomings of conventional consensus algorithms in control performance, this invention proposes a distributed collaborative controller for microgrid clusters suitable for fault emergency scenarios, creating conditions for the "plug-and-play" and "plug-and-play optimal" capabilities of mobile emergency power supplies, while simultaneously improving the flexibility and resilience of microgrid clusters.

[0165] One embodiment of the present invention provides an emergency collaborative control system for microgrid groups, comprising:

[0166] The first preprocessing module is used to establish an active power and reactive power sharing controller based on the system steady-state convergence formula and the average value estimation model of active power and reactive power, and to obtain the active power and reactive power sharing control compensation amount.

[0167] The second preprocessing module, fault routing, provides frequency and / or voltage support for mobile energy storage through pre-synchronized emergency access. It obtains the compensation amount that meets the requirements of active power distribution and state of charge balance of mobile energy storage through the average value estimation model of active power and reactive power and the linear quadratic regulator.

[0168] The processing module is used to construct event triggering conditions based on the estimated average imbalance and information transmission error; and is used for fault recovery, enabling seamless withdrawal of mobile energy storage through power transfer between supply and demand.

[0169] The control module achieves various control objectives of the system by controlling the compensation amount based on the equal distribution of active and reactive power, as well as the compensation amount that satisfies the equal distribution of active power and the balance of state of charge of mobile energy storage.

[0170] Embodiments of this application may be provided as methods or computer program products. Therefore, this application may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of this application may be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0171] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0172] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0173] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0174] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A method for emergency coordinated control of microgrid groups, characterized in that, include: Based on the system steady-state convergence formula and the average value estimation model of active power and reactive power, an active power and reactive power sharing controller is established to obtain the active power and reactive power sharing control compensation quantities. In the fault-free operation, mobile energy storage provides frequency and / or voltage support through pre-synchronized emergency access. The compensation amount that meets the requirements of active power distribution and state of charge balance of mobile energy storage is obtained through the average value estimation model of active power and reactive power and the linear quadratic regulator. The event triggering conditions are constructed by the imbalance of the estimated average value and the information transmission error. Fault recovery enables seamless decommissioning of mobile energy storage through power transfer between supply and demand. The system achieves various control objectives by controlling the compensation amount based on the equal distribution of active and reactive power, as well as the compensation amount that satisfies the equal distribution of active power and the balance of state of charge in mobile energy storage. The fault routing involves mobile energy storage providing frequency and voltage support through pre-synchronized emergency access. Compensation amounts that satisfy the active power distribution and state-of-charge balance of mobile energy storage are obtained through an active and reactive power average estimation model and a linear quadratic regulator. Specifically, this includes: After the system is disconnected from the fault, the mobile energy storage is smoothly connected to the faulty microgrid by adjusting the voltage phase angle and amplitude on both sides of the synchronization connection point. r： in, β r,m Characterizing faulty microgrids r The Middle m The working status of mobile energy storage. β r,m =1 indicates that mobile energy storage needs to be connected to the system. β r,m =0 indicates that the system has been connected; and This is a pre-synchronization compensation item; The phase angle difference of the voltages on both sides of the connection point; The voltage phase angle difference and amplitude difference on both sides of the access point; k θr,m and k Er,m The integral coefficient; The actual output angular frequency of each DG and mobile energy storage in the faulty microgrid is calculated using the following formula. ω r,i Restored to the system's rated angular frequency ω Meanwhile, the key bus voltage V rc Restore to rated value ： and This is the compensation amount for frequency / critical bus voltage recovery; k ωr , i and k vr , i The integral coefficient; g r,i Meter power supply i Whether to receive critical bus voltage rating information, if so g r,i =1, receive the information; otherwise, do not receive; there is one and only one power source in the faulty microgrid that can receive the information; Will be connected to the faulty microgrid r Mobile energy storage m As one of the distributed power sources i The neighboring nodes are used to estimate the average power of each power source and the average state of charge (SOC) value of each mobile energy storage unit using an average active and reactive power estimation model. Establish a mobile energy storage active power sharing-SOC balancing collaborative controller according to the following formula: in, For mobile energy storage m Active power - SOC collaborative compensation amount; k Sr1,m and k Sr2,m These are the integral coefficients for controlling the active power distribution and SOC balancing of mobile energy storage, respectively. ρ r,m For faulty microgrids r Internal mobile energy storage m The SOC value.

2. The microgrid group emergency coordinated control method according to claim 1, characterized in that: The system steady-state convergence equations include steady-state convergence equations for active and reactive power between microgrids, as well as steady-state convergence equations for active and reactive power within each microgrid. The steady-state convergence equations for active and reactive power between microgrids include: Based on the coordinated control objective of power sharing by capacity among interconnected microgrids, the following equation is established: In the formula, Indicates the status of the interconnection switch between interconnected microgrids X and Y. =0 indicates a closed loop. =1 indicates disconnection; m X,i and n X,i Representing the first term in microgrid X respectively i Active and reactive droop coefficients of a distributed power source; m Y,j and n Y,j Representing the first term in microgrid Y respectively j Active and reactive droop coefficients of a distributed power source; and They represent t The average active and reactive power output of the microgrid at any given time; and They represent t Average active and reactive power output of microgrid Y at any given time; The steady-state convergence equations for active and reactive power within each microgrid include: Based on the coordinated control objective of distributing active and reactive power output according to capacity among distributed power sources in each microgrid, the following equation is established: in, P X,i ( t )and P X,j ( t ) respectively represent t The first microgrid X in time i and the j The active power of a distributed power source; Q X,i ( t )and Q X,j ( t ) respectively represent t The first microgrid X in time i and the j The reactive power of a distributed power source.

3. The microgrid group emergency coordinated control method according to claim 2, characterized in that: The establishment of the average value estimation model for active power and reactive power includes: For distributed power sources within each microgrid, the active and reactive power values ​​are calculated by sampling the output voltage and current at the current moment. Combined with the average information of the state variables of other nodes already obtained locally, and using all locally known information, the intermediate temporary variable representing the equal distribution of active and reactive power is calculated using the following formula. ( ), ( ): in, k Indicates the number of iterations; γ X,i = m X,i P X,i and η X,i = n X,i Q X,i Representing the first term in microgrid X respectively i The product of the active and reactive power of a distributed power source and its droop factor; w γX,i ( w ηX,i ) indicates the first i Weighting information of active (reactive) power of each distributed source in the average value estimation; s γj→i ( s ηj→i ) for distributed power j Passed to neighboring nodes i But it does not contain nodes. i Weight values ​​for active (reactive) power distribution information; x γj→i ( x ηj→i ) for distributed power j Passed to neighboring nodes i But it does not contain nodes. i The average value of active (reactive) power in the state variables, weighted by weight. N i For nodes i The set of neighboring nodes; Using the obtained intermediate temporary variables, substitute them into the following formula to dynamically estimate the average value of active power and reactive power: in, and They represent the first in microgrid X, respectively. i The average value of active and reactive power state variables obtained by local estimation of each distributed power source; Calculate the distributed power source in the next time step i Information that needs to be passed to each neighboring node.

4. The microgrid group emergency coordinated control method according to claim 3, characterized in that: The establishment of the active and reactive power sharing controller to obtain the active and reactive power sharing control compensation amounts specifically includes: The active and reactive power sharing control compensation includes active and reactive power sharing controllers between interconnected microgrids and active and reactive power sharing controllers within each microgrid. Establishment of the active and reactive power sharing controllers among the interconnected microgrids: in, and The compensation amount is evenly distributed between active and reactive power in interconnected microgrids; k PXY,i and k QXY,i The integral coefficient; The establishment of the active and reactive power sharing controllers in each microgrid: in, and This is the compensation amount for the active and reactive power of distributed power sources within microgrid X. k PX,i and k QX,i is the integral coefficient.

5. The microgrid group emergency coordinated control method according to claim 4, characterized in that: The k Sr1,m and stated k Sr2,m The optimized design is as follows: Establish a state-space model for mobile energy storage Based on this state-space model, the following algebraic Riccati equation is constructed: in, A and B It is a positive definite matrix; C and D The state matrix for mobile energy storage; Solving the equation yields a unique positive definite solution. R r The optimized control parameters are obtained from the following formula. K r =[ k Sr1,m , k Sr2,m ] T : 。 6. The microgrid group emergency coordinated control method according to claim 5, characterized in that: The construction of event triggering conditions based on the estimated average imbalance and information transmission error specifically includes: Calculate the error in the transmission of weight information in the dynamic convergence algorithm. e s,i→j Error in state quantity information e x,i→j : in, h i ( k )=argmin h { k - ti h | k - ti h ≥0}, ti h Determine the necessary triggering times for the built-in event detection module; The imbalance quantity is calculated by the average value of the state variables estimated by the dynamic convergence algorithm. μ i ( k )= Constructed event triggering conditions: in, ζ i→j =[ e x,i→j , e s,i→j ] T Ξ=diag( φ 1, φ 2) is the coefficient matrix. σ i This is the trigger threshold parameter.

7. The microgrid group emergency coordinated control method according to claim 6, characterized in that: The fault recovery, achieved through power transfer to seamlessly deactivate mobile energy storage, specifically includes: For faulty microgrids r Distributed power sources within i The power transfer controller is set up as follows: For faulty microgrids r Mobile energy storage within m Assuming shared access M One, the power transfer controller is set as follows: in, α r,m =1 indicates that the mobile energy storage needs to be removed from the system. k Δpr,i , k Δqr,i , k Δpr,m , k Δqr,m Δ is the integral coefficient. P r,m and Δ Q r,m The active and reactive power outputs before the mobile energy storage is decommissioned.

8. The microgrid group emergency coordinated control method according to claim 7, characterized in that: The system achieves various control objectives by controlling the compensation amounts based on the equal distribution of active and reactive power, frequency and voltage recovery compensation amounts, and compensation amounts that satisfy the equal distribution of active power and state of charge balance in mobile energy storage. Specifically, this includes: The total compensation amount Ω is obtained by summing up the compensation amounts of the distributed power sources. X(r),i and Φ X(r),i The total compensation amount Ω is obtained by summing the compensation amounts of various mobile energy storage systems. r,m and Φ r,m These are then added to their respective droop control equations to collaboratively achieve the system's various control objectives: 。 9. A microgrid group emergency collaborative control system, characterized in that, The system is used to implement the microgrid group emergency collaborative control method according to claim 8, and the system includes: The first preprocessing module is used to establish an active power and reactive power sharing controller based on the system steady-state convergence formula and the average value estimation model of active power and reactive power, and to obtain the active power and reactive power sharing control compensation amount. The second preprocessing module, fault routing, provides frequency and voltage support for mobile energy storage through pre-synchronized emergency access. It obtains the compensation amount that meets the requirements of active power distribution and state of charge balance of mobile energy storage through the average value estimation model of active power and reactive power and the linear quadratic regulator. The processing module is used to construct event triggering conditions based on the estimated average imbalance and information transmission error; and is used for fault recovery, enabling seamless withdrawal of mobile energy storage through power transfer between supply and demand. The control module achieves various control objectives of the system by controlling the compensation amount based on the equal distribution of active and reactive power, as well as the compensation amount that satisfies the equal distribution of active power and the balance of state of charge of mobile energy storage.

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